Author Topic: Jet Powered First Stage  (Read 83491 times)

Offline Rocket Science

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Jet Powered First Stage
« on: 05/10/2011 02:01 pm »
On and off for several years I thought about this. Horizontal vs. vertical jet powered first stage. I see there is interest in discussing this concept again.
Here is a link...

http://yarchive.net/space/launchers/jet_first_stage.html
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #1 on: 05/10/2011 05:18 pm »
Let me "help" a bit since I seem to have been an "instigator" on this :)
Some other sites with messages and threads concerning both the original proposal and variants: (The whole thing is so spread out around the internet :) )
http://groups.google.com/group/sci.space.science/browse_thread/thread/899862adfe47137c/e88d1bac5bbf31dd?lnk=st&q=#e88d1bac5bbf31dd

http://groups.google.com/groups?as_ugroup=sci.space.policy&as_uauthors=Dani+Eder&as_usubject=spaceflight+manned+end&as_drrb=b&as_mind=20&as_minm=7&as_miny=1995&as_maxd=22&as_maxm=7&as_maxy=1995

http://groups.google.com/groups?as_ugroup=sci.space.tech&as_uauthors=Dani+Eder&as_usubject=engine+stages+first&as_drrb=b&as_mind=19&as_minm=9&as_miny=1995&as_maxd=21&as_maxm=9&as_maxy=1995

The following is a summery of notes and information I've managed to find on the concept on the internet over the years. Please keep in mind I've not actually ever been able to get in contact with the originator of this concept and I make no claim on it I'm just passing it on for FYI purposes.
Quote
Various Notes for Fly-back Jet Engine Booster Pod concept.

Review of original concept information.

First mention found in internet Archive files of concept by Dani Eder of Boeing:

Jet Boosted/Jet Assisted Launch vehicle, posted 1995 @18 July.

Supposedly done for study by Boeing for a minimum Non-Capital Intensive Launcher concept.

•   -10 Pratt & Whitney F100-229 military afterburning turbofan jet engines (F-15 fighter engines) ‘strapped-on’ to a two-stage “Core” vehicle.
•   Total vehicle lift-off mass listed as “145,000lbs” in this entry, a later entry (dated 2 October) listed the total vehicle weight as 154,000lbs. “Core” vehicle mass is listed as 85,000lbs in the first entry and 94,000lbs in the second entry with the mass of the 10 jet engine ‘modules’ remaining constant at 6,000lbs each or 60,000lbs total.
•   Payload to orbit is listed as 6,600lbs as optimized by the POST trajectory program, and ‘assumed’ to average 6,000lb.

The original posted idea is as follows:
•   Total vehicle mass is 145,000lbs at take off consisting of:
•   10 ‘modular’ jet engine pods each weighing 6,000lbs which consist of:
-   One each P&W F100-229 engine weighing 3,700lbs
-   1300lbs of “other” equipment including module structure, landing legs, parachute, fuel tanks, mounting structure, and other equipment for operation.
-   1000lbs of jet fuel
•   A two-stage Core vehicle which consisted of three parallel tank and structure modules each powered by two Pratt & Whitney RL-10 LH2/Lox  rocket engines. The two ‘side’ modules comprised the ‘first’ stage, and were staged off as they ran dry of propellant. The center module was longer than the first stage modules and had more robust entry protection as well as mountings for a payload at the forward end. Each module was to share a common tank diameter and plumbing to reduce production costs. Each module was to be no more than 2 meters in diameter to allow return to launch site shipment using standard shipping containers.
•   On take off all 10 jet modules would be under full afterburner power and lift the entire vehicle with an acceleration of around 2 gravities. The jet modules would operate for about 60 seconds, (later changed to 80 seconds) pushing the Core vehicle to 50,000ft at Mach 1.7 (@500 meters per second) and a flight path angle of 35 degrees.
•   At this point all 6 RL-10 motors were started while the jet modules were staged off and steered away from the flight path using residual thrust. (Launch velocity at this point would be equivalent to the jet modules and/or core vehicle ballistic ally coasting up to 90,000ft if no rocket power were applied)
•   The jet modules would ‘steer’ towards a pre-determined landing point using residual thrust prior to fuel depletion and deploy parachutes and non-shock absorbing legs to land. They would then be picked up, (landing was estimated to be within 10 miles of the launch point) by a truck equipped with a crane and transported back to the launch site for inspection, repair, refueling and reuse.
•   The Core vehicle would continue on burning all 6 engines in parallel until the propellant was exhausted from the two side modules. At this point they would be ‘staged’ with the larger central module continuing to power into LEO. The first stage modules would reenter and deploy parachutes for a landing at sea. They too would be recovered, inspected, and shipped back to the launch site for refurbishment, refueling and reuse.
•   The central module would deliver 6,000lbs (net) payload to LEO and then de-orbit, reenter, deploy parachutes and land near the launch site to be refurbished, refueled and reused.

Development, production, and operations costs were based on Boeing experience and prices quoted to the author by various manufacturers.
•   Total vehicle development costs were estimated from Boeing experience up to and including the 777 aircraft with aerospace hardware development scaling as a 0.75 power of hardware weight with development cost being 6 2/3% or around $300 million dollars. It was assumed that with no need for an extensive production line, and no need to certify the vehicle to airline safety standards the overall development price could be reduced to $200 million, or by 1/3rd the cost.
•   Ground crew costs were estimated at 10 people for the rocket with another 10 for the jet engines and 10 for ‘overhead’ functions (30 people total) equaling around $2.4 million dollars per year.
•   Flights were assumed at least once per week for a ground crew cost of $50,000.00 per launch, jet and rocket fuel accounting for $40,000.00 per launch. The jet engines were assumed to be acquired surplus/used for about $2 million dollars each and the RL-10 engines new for $3.5 million each. Vehicle acquisition was projected to be around $20 million dollars per unit for small quantities and scaled from aircraft production figures.
•   Total operations costs per launch were estimated at $747,000.00 per launch including amortized development and interests costs on all over 200 launches for the vehicles, 40 for the RL-10s and effective unlimited for the jet engines.
•   Approximate total price per launch was estimated to be $ 1.5 million dollars. ($250.00 per pound/$750,000.00 per person assuming a two person launch)

A later post found (dated June 20, 2001) extends the Jet module afterburner run from 60 to 80 seconds and amends the vehicle speed at staging of the jets from the Mach 1.7 above to only Mach 1.6 but still notes this ‘is’ @500 meters per second velocity. This post also now states that the jets will recover within 20 miles of the launch point instead of only 10.
Another post notes the “total” vehicle weight as 100,000lbs instead of the above 145,000 or 154,000lbs. No citation is given for this change. The same post notes that “about 5%” of this weight is payload to orbit, or only 5,000lbs, noting “that’s about half the payload of a Delta II, if I recall” at the end of the post.

Further this post recalls that the flight trajectory and staging timing was optimized by the Boeing using the POST trajectory program for best payload to orbit and that the level of detail in the analysis included jet thrust as a function of altitude, speed, angle of attack, and other factors pertaining to jet engine operations.

In an extension and expansion on the idea by one William Mook dated 25 June, 2001 he notes that the ‘costs’ as given are:
•   $20 million dollars for rocket engines (RL-10)
•   $6 million for ‘other’ engineering
•   “Four” jet engine modules, (it seems to assume multiple jet modules but no details and 4 does not divide into 10 so I have no idea if the number of engines changed) at $20 million each. (Four modules at $20 million each comes to $80 million)
•   Mr. Mook then states “So, for less than $46 million in capital costs and less than $1 million in recurring costs” which makes no sense given the numbers stated.

Mr. Mook then goes on to discuss trying to ‘reduce’ the quoted capital by suggesting that TRW LH2/Lox engines could possibly be purchased for only $1 million each, and would operate at a higher pressure. He then suggests the possibility of acquiring jet engines for less than $1 million each, with a total cost being brought down to close to $10 million dollars. (Again the numbers are off)

He then goes on to give the mathematics involved for a proposed vehicle which has the following characteristics:
•   Four Jet modules at 5,000lbs each carrying 2,700lbs of jet fuel per module. Each module would be equipped with wings similar to those on a cruise missile for return flight from 20 miles.
•   Two equal weight rocket stages each weighing 5,325lbs each with a single 30,000lb rocket engine each capable of ‘cross-feeding’ fuel to each other, and an assumed 15% structural fraction. (He suggests and I agree that deep throttling capability is needed and that the rocket should be started at prior to take off and throttled back to around 10% thrust. This would increase safety AND add assistance to the jets to make them more efficient.)
•   On take off each rocket stage will throttle back to 10% of full thrust while one stage, (Booster) feeds propellant to its own engine AND cross feeds propellant to the second (Orbiter) stage engine.  The Booster rocket has 30,175lbs of propellant, while the Orbiter stage only carries 27,000lbs of propellant but has space and payload ability for 3,175lbs to orbit.
•   Once the jet modules stage at 50,000ft and Mach 1.6, both rockets advance to 100% throttle until the Boosters propellant is depleted and it is staged off. The Orbiter continues using its on-board fuel to orbit. The Booster reenters and glides to a recovery. (I have no specifics where this is, though Mr. Mook adds a twist with this stage being ‘snagged’ in mid-air by a jet powered tow plane and towed back to the launch point)

How ‘possible’ any of this is depends on someone checking Mr. Mooks flight math and seeing it is correct or not :o)

Recall that ALL stages and parts are recovered after the mission so while this is basically a 3STO it is STILL and RLV.
Thanks...
Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Danderman

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Re: Jet Powered First Stage
« Reply #2 on: 05/10/2011 06:20 pm »
Ignoring for a moment the point design described above, I suspect that strap-on, non-recoverable, jet engines would do wonders for Falcon 1 payload capability at minimal cost.

Once wings are invoked, however, its game over.

Offline fatjohn1408

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Re: Jet Powered First Stage
« Reply #3 on: 05/12/2011 05:19 pm »
This is only viable when launched horizontally. Most jets do not have a large thrust to weight ratio. So they hardly transfer any force from them to your rocket fuselage. Imagine a jet with a T/W of 5 strapped to a rocket that is accelerating with 5 G. How much force would be transfered from the jet to the main rocket stage? None. You could just detach both and they would fly alongside each other with no added effect if you attach them or not.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #4 on: 05/12/2011 08:41 pm »
This is only viable when launched horizontally. Most jets do not have a large thrust to weight ratio. So they hardly transfer any force from them to your rocket fuselage. Imagine a jet with a T/W of 5 strapped to a rocket that is accelerating with 5 G. How much force would be transfered from the jet to the main rocket stage? None. You could just detach both and they would fly alongside each other with no added effect if you attach them or not.
Ok, number one I'm guessing you haven't even taken a look at the links?

Number two jet engine can have higher thurst-to-weights see the POGO/JELAC (Jet Engine Launch Assist Concept) here:
http://home.earthlink.net/~altaccel/pogo/pogintro.htm

Since Danderman brought it up lets postulate a F-100 powered JELAC stage for the Falcon-1.

Falcon-1 gross take-off weight: 85,000lbs
Falcon-1 gross-take off thrust: 125,000lbs

The Pratt-&-Whitney F100-200/229 After-burning Low-bypass Turbofan engine has a standard "dry" (no afterburning) thrust of 17,800lbs and a "wet" (After-Burner) thrust of 29,160lbs. Assuming a simple "strap-on" type pod such as suggested by Dani Edar with simple parachute recover, (para-foil in a more modern version so that it could be recovered on-land at the launch site) all the structural and fuel needs as well as the all-up engine are contained in a 6000lb "pod" as I noted.

Five (5) each pods will give a gross take off thrust of 145,800lbs and would bring the total gross lift off mass to 115,000lbs. As a simple expediant I'll up the GTO mass to 120,000lbs because the Merlin-1C  on the Falcon-1 would have to be modified to include a nozzle extension for optimum operation above 50,000ft*.

Flight profile is as follows. Lift off and flight to Mach-2 and 50,000ft* with a "staging" AoA of 35 degrees would be handled by the JELAC system with the Falcon-1's 1st stage engine started on the ground prior to lift off but throttled back until just before JELAC release. The Merlin-1C is throttled up to full thrust (125,000lbs) as the JELAC's are staged at the one-minute mark, the JELACs steer clear of the Falcon-1 and back towards the launch site on risidual thrust at fuel exhaustion. The para-foils are released and simple radio beacon homing guides them into a landing near the launch site for pick up and recovery.

The Falcon-1 has 99% of it's propellant left at staging, but has an exsisting deta-V of 663 m/s at 50,000ft*. I'm not sure how to calculate the possible payload increase, anyone want to take a shot at that?

The engines were costed by P&W as surplus, high-hour engines at around $2-million dollars each including modifications for this use in the mid-90s and each "flight" while "high-performance" for a rocket engine is less than a single flight hour on the engines themselves. Recovery, inspection, maintenance, and readying on each engine would only require at the most an hour each. It might be better in this case to actually bypass increased payload for a more robust structure for the Falcon-1 itself and a higher-end recovery system in order to demonstrate a fully recoverable launch system.

I'll also point out that as I said this is a very SIMPLE example system, there is a large amount more that could be done at minimum cost to improve performance of the JELACs such as adding an injection system to increase thrust and operational range of the system.

Water injection is a proven method of increasing thrust on a jet engine with on average a doubleing of thrust at specific altitudes. (Example with the above system, 29,160 becomes 58,320 at take off and around half that, or a little over 29,000lbs at 45,000ft*) In addition injection of LOX into the intake system optimized for combustion chamber stabilization would ensure that the engines would operate at maximum even if air-recovery was non-optimul as it would be at higher altitudes and speeds. Possibly allowing operations of the JELAC at Mach-3 and altitudes up to 80,000-to-100,000ft*.

Even without the operational advantages of these simple augmentation schemes they would allow the basic JELAC to be reduced instead of five (5) engines being require for the Falcon-1 with the augmentation systems you would only need three (3) engines for the system. (Technically only two {116,640lbs} but three {174,960lbs} gives a better performance margin and engine-out tolerance) While there is a general lowering in ISP and added mass to the JELAC pods the overall performance and lowered engine costs would compensate.

Seriously, what's NOT to like about this? :)

Randy
*= Corrected numbers to my OWN posted notes... Yeesh, need to read my OWN posts I guess :)
« Last Edit: 05/23/2011 09:53 pm by RanulfC »
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #5 on: 05/20/2011 07:54 pm »
Again from another thread:
Quote from: Patchouli
Keep in mind if you can get a rocket to close to Mach 2 and 30,000 feet you just cut the first stage mass by 30% or more.
*Found the "quote" in context:
http://forum.nasaspaceflight.com/index.php?topic=24756.msg736390#msg736390

Randy
*Edit to embed information
« Last Edit: 05/24/2011 01:44 pm by RanulfC »
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline tnphysics

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Re: Jet Powered First Stage
« Reply #6 on: 05/21/2011 02:34 pm »
Again from another thread:
Quote from: Patchouli
Keep in mind if you can get a rocket to close to Mach 2 and 30,000 feet you just cut the first stage mass by 30% or more.

Randy

Could you please elaborate?

BTW the idea is AWESOME. Maybe you could use LOX/water injection for even better performance, and swap the engines for already Mach 3.2 capable J58s.

Offline Rocket Science

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Re: Jet Powered First Stage
« Reply #7 on: 05/21/2011 03:08 pm »
Again from another thread:
Quote from: Patchouli
Keep in mind if you can get a rocket to close to Mach 2 and 30,000 feet you just cut the first stage mass by 30% or more.

Randy

Could you please elaborate?

BTW the idea is AWESOME. Maybe you could use LOX/water injection for even better performance, and swap the engines for already Mach 3.2 capable J58s.
Have the engines fly home like the D-21 Drone...

http://www.wvi.com/~sr71webmaster/d21~1.htm
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline Danderman

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Re: Jet Powered First Stage
« Reply #8 on: 05/21/2011 11:19 pm »
I would suggest the KISS principle when  invoking jet engines; use existing engines without modifications. Once you start adding requirements like flyback boosters, the whole concept sinks into a morass of unexpected constraints.

Offline DarkenedOne

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Re: Jet Powered First Stage
« Reply #9 on: 05/22/2011 12:25 am »
Ignoring for a moment the point design described above, I suspect that strap-on, non-recoverable, jet engines would do wonders for Falcon 1 payload capability at minimal cost.

Once wings are invoked, however, its game over.


First of all, jet engines are usually pretty expensive, so I doubt that throw away jet engines would be worth it. 

Secondly why in hell would you make them non-recoverable.  Jet engines are great because they can be used many times. 

Offline Danderman

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Re: Jet Powered First Stage
« Reply #10 on: 05/23/2011 06:29 pm »
Ignoring for a moment the point design described above, I suspect that strap-on, non-recoverable, jet engines would do wonders for Falcon 1 payload capability at minimal cost.

Once wings are invoked, however, its game over.


First of all, jet engines are usually pretty expensive, so I doubt that throw away jet engines would be worth it. 

Secondly why in hell would you make them non-recoverable.  Jet engines are great because they can be used many times. 

As long as you are willing to pay for the project to make the jet engines recoverable, great. Otherwise, lowering DDT&E costs is the key to someone using jet engines to increase vehicle performance.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #11 on: 05/23/2011 09:40 pm »
Quote from: tnphysics
Quote from: RanulfC
Again from another thread:
Quote from: Patchouli
Keep in mind if you can get a rocket to close to Mach 2 and 30,000 feet you just cut the first stage mass by 30% or more.
Could you please elaborate?
Love him too :) I already asked him by pm to add comment if he would :)

Quote
BTW the idea is AWESOME. Maybe you could use LOX/water injection for even better performance, and swap the engines for already Mach 3.2 capable J58s.
I addressed the concept above, though being honest you'd ONLY need the "LOX" injection for above Mach-3 flight and that's probably longer than you want to keep the engines if they aren't part of the vehicle.
(Since this is "just" a Launch Assist" concept)

As to the J-58 it's a nice and capable engine, but it's maintenance intensive and really TOO much for the concept.
http://www.hill.af.mil/library/factsheets/factsheet.asp?id=5786

You might want something like that for a vehicle engine but not as a booster.
Quote from: Rocket Science
Have the engines fly home like the D-21 Drone...
"Technically" the D-21's DIDN'T "fly-home" they ejected the recon-pod and then self-destructed... But I "get" what you mean :)
(See Below)

Quote from: Danderman
I would suggest the KISS principle...
Well if I was doing THAT I'd just suggest sticking with Solids and strapping some "GEMs" to the rocket :) Or maybe just use the "steam-rocket" booster suggested here:
http://ambivalentengineer.blogspot.com/2006/02/catapult-gain.html which amounts to around the same thing in a REALLY simple package. But since I'm "invoking" jets anyway... :)
Quote
... when  invoking jet engines; use existing engines without modifications.
Which WAS the "basic" suggestion I was quoting after all. (Noting again: This is not a concept "I" originated but is contained within the internete thread quoted in the original post, and is based on a design-study done by Dani Edar when he worked for Boeing.)

Beyond some basic modifications to allow the engine to start and operate in a vertical position, (its designed to operate in ANY position AFTER it's started but it's SUPPOSED to be started in a horizontal position :) ) the majority of "modification" is putting a shell around the engine to contain the electronic control systems, the fuel, a basic "landing" parachute (or para-foil as I noted is more likely) and spring legs to absorb the landing shock.

While wings were not part of the original concept "fly-back" was discussed with either steerable parachutes or folding wing similar to a cruise-missile. Since the original study parameters were "minimum-start-up-and-operations-costs" straight parachute recovery within 40-80 miles "down-range" from an inland (West Texas suggested) Launch Site by a single truck with a crane and perhaps four (4) was deemed the most fitting.

No issues were found with the "fly-back" methods though at the time (late '70s to mid-80s) it was thought to probably require more time/money/resources than simple parachute recovery.

A deployed para-foil and mid-air recovery would allow a wider range of launch site options to be used and is a proven technique so that's the one "I" lean towards if "I" were doing a JELAC-type "jet-assist" pod method such as outlined above.

Now while the original concept was single engine pods it was pointed out that nothing actually precluded multi-engine pods, and in some cases having more than one engine in a 'pod' "scaled" better. The "end" point of THAT direction is a launch-assist "vehicle" in the manner of Glenn Olson's "POGO" launch assist:
http://home.earthlink.net/~altaccel/pogo/pogintro.htm
http://home.earthlink.net/~altaccel/pogo/pogconcl.htm
Which shows JELAC to be a valid concept, (but like most it lacks a "viable-marketing" economic vis-a-vis current launch practices) even including vehicle development and operations costs. However, neither the original study, the work on POGO, nor my own suggestions really deal with the underlying "issue" between concept and implementation which boils down to low-flight-rates and a flat launch market :)

Pretty much the biggest "draw" to the idea of using jet engines for launch assist is the HUGE amount of "Mean-Time-Between-Major-Maintenance/Failure" a jet has compared to a rocket engine. Jet engines are rated in "hours" while rockets engines are rated in "seconds" (even the RL-10 is rated in "seconds" even though it TECHNICALLY could be rated in "minutes" being "good" for around 600 seconds of "use") Even a "high-time" jet engine has "hours" of useful life left with minimum maintenance time-and-costs compared to a rocket engine.

In the original concept the engines were "used-high-time" engines bought through P&W from the Air Force as they were phased out and the quoted price per engine (with modifications and "podded) at a little over $2-Million dollars each. Each engine "only" had about from 60 to 100 'hours' left before they would need a total "rebuild" from the ground up, (which no one actually DOES since the cost of the rebuild usually equals or greatly exceeds the "worth" of the engine by this point) and they were only run 60-to-80 SECONDS per flight.

(Worst case? 60-"hours" is 3600 "minutes" or 216,000 seconds which if used for 80-seconds a flight gives you about 2700 "flights" even for a low-time engine)

The biggest "hurdle" in cost of recovery is picking up and returning the engines to the launch site for refurbishment. The original concept had 4 guys and a large flat-bed truck with a crane driving out into the prarie to safe the engines and hoist them onto the truck and then driving back to the launch site. Expanding that a bit I don't see an express "need" for the flat-bed if you can have the engine pods guided back to the launch site though it might be "better" all around to eat some extra operations costs and have them air-snatched and lowered onto a barge platform or ship for coastal sites or onto an airbag and then trucked or train to the launch site. In the end it is highly dependent on the overall operations plan and how high a flight rate you get going.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #12 on: 05/23/2011 09:48 pm »
Ignoring for a moment the point design described above, I suspect that strap-on, non-recoverable, jet engines would do wonders for Falcon 1 payload capability at minimal cost.
Once wings are invoked, however, its game over.
Going back to the ORIGINAL post here I see two "issues" with the suggestion:
1) At issue with the Falcon-1 payload is the fact it's a "partially-pressure-supported" design and PROBABLY can't actually USE "launch-assist" of any sort which pretty much negates the whole argument, both yours AND mine :)

(Once you start "assuming" a rebuild of the basic vehicle itself to ALLOW "launch-assist" though they are more expensive-per-flight you would actually get more use out of Solid-GEMs than jets since the gems don't require the more "depressed" intital flight angle {35-degrees at 50K feet recall} and are available already)

2) IF you were only using the jet-engines once and throwing them away, you lose the biggest "savings" factor over other methods: The "hours" between high-end maintenance for the jet engines. So ANY "recovery" method tends to even out as long as you are USING the jets enough. (Lower flight rates and the jet-engines end up sitting there "costing" money on a daily basis instead of being used)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #13 on: 05/24/2011 03:59 pm »
Now a "point" I've tried to make here is that the JELAC concept is at it's most basic simply "Podding" individual engines into a simple aeroshell with dedicated fuel, electronics, controls, fuel and a simple recovery system as per the original concept:
http://yarchive.net/space/launchers/jet_first_stage.html

This included having multiple engines per "pod" (three {3} would be a good number for the above "point-design" example of the Falcon-1 since it is such a small diameter actually "fitting" the engine pods would be problematical) and also incorperation of more advanced "fly-back" recovery systems.

All around performance was between Mach-1.5 to Mach-2 and 50,000ft+.

NOTE: I should point out here that while "I" use the example of a Falcon-1 rocket I am pretty sure that barring a large amount of redesign work and re-building the Falcon-1 is unsuitable for ANY kind of launch assist given it's partially pressure stabilized design. On the other hand, given a "launch-assist" the structural margins of the vehicle CAN be increased with little or no loss of payload so if Space-X was 'interested' in the idea.... :)

At some point as you scale "up" towards larger payloads it becomes convinyent to simply make the multi-engine pod an actual intergrated "vehicle" design as a complete booster stage. This is the idea behind the POGO concept:
http://home.earthlink.net/~altaccel/pogo/pogintro.htm

Though to be "honest" the actual POGO itself doesn't help all that much because it's "Mach" limited by the use of "standard" launch vehicle for lower-cost "off-the-shelf" type operations. In most examples you would have to have a specially designed and built "upper-stage" Launch Vehicle to allow for full use of the POGO launcher OR intergrate a "bay" in which to store the LV until the vehicle-stage gets above a majority of the practical atmosphere. Still well designed and intergrated the POGO would get the LV up to around Mach-4+ and 100,000ft or more before "starting" it on it's way.

The there is what I tend to think of as the "combination" system; Small, jet powered aircraft "pods" that can be attached to a system (something like a spaceplane for the most part) and used to accelerate it up to around Mach-4+ and 100,000ft, Basically similar to the NASA "SpaceJet" concept.

Of course NONE of these actually address the basic issue of "why" economics versus the current systems.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Patchouli

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Re: Jet Powered First Stage
« Reply #14 on: 05/26/2011 07:54 pm »
It might be more cost effective to go ahead and modify or design an aircraft to use as the first stage vs messing with VTOL pods.
This is the route Scaled took.

HTOL does give much better abort options then are possible with VTOL and even super sonic aircraft are a mature technology.

The already existing B1B can carry 56,700kg maybe more if fuel is off loaded.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #15 on: 05/26/2011 09:16 pm »
The already existing B1B can carry 56,700kg maybe more if fuel is off loaded.
Ahhh, ok.. Folks have to be a bit more "careful" when quoting stuff like this :)

See the B1B CAN "carry" that much but it has to be carried over (and through) three "bomb-bays" over the length of the aircraft. (Two aft, one forward with a fuel tank space in the middle)

And "technically" there is a serious issue with the forward end of the forward bay as the crew-boarding ladder actually extends to the ground at an angle that cuts off some access towards the forward bulkhead if your hanging something on the belly :)

Then there is the "issue" with going supersonic with "dangly-bits" hanging in the airstream... (We would also have to consider how to get the Air Force to actually give up the air-frames too which won't be easy :) )

"Cost" is of course one of the biggest issues with just about ANY Launch Assist scheme, especially a supersonic one. The problem is there aren't any "good" civilian supersonic designs that can be used and the majority of the military ones are unavailable. (Or too small)

Which ends up coming back to either a more focused "point-design" type of "minimum" aircraft, or custom (which is what I'd considered the White-Knight aircraft) small production platform if you want "higher-performance" assist.

I agree that HTOL has a lot more "benign" abort options than VTOL but it tends to pretty much "even-out" if you design for engine-out situations. HTOL REALLY shines for lift-off mass IMHO since you don't HAVE to have a high thrust-to-weight if you have wings, but that harkens right back to a "carrier" aircraft versus plain-old launch assist concepts.

A thought has been going around in my brain over the Garvey NanoSat Launch Vehicle (http://www.garvspace.com/NLV.htm, http://www.garvspace.com/NLV_mockup.htm) and adding some "Jet-Pods" using Cruise-Missile/UAV jet engines to do small scale testing.

It would be a LOT cheaper than trying a full-scale, full-up program at any rate :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Patchouli

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Re: Jet Powered First Stage
« Reply #16 on: 05/27/2011 12:36 am »
The already existing B1B can carry 56,700kg maybe more if fuel is off loaded.
Ahhh, ok.. Folks have to be a bit more "careful" when quoting stuff like this :)

See the B1B CAN "carry" that much but it has to be carried over (and through) three "bomb-bays" over the length of the aircraft. (Two aft, one forward with a fuel tank space in the middle)

And "technically" there is a serious issue with the forward end of the forward bay as the crew-boarding ladder actually extends to the ground at an angle that cuts off some access towards the forward bulkhead if your hanging something on the belly :)

Then there is the "issue" with going supersonic with "dangly-bits" hanging in the airstream... (We would also have to consider how to get the Air Force to actually give up the air-frames too which won't be easy :) )

"Cost" is of course one of the biggest issues with just about ANY Launch Assist scheme, especially a supersonic one. The problem is there aren't any "good" civilian supersonic designs that can be used and the majority of the military ones are unavailable. (Or too small)

Which ends up coming back to either a more focused "point-design" type of "minimum" aircraft, or custom (which is what I'd considered the White-Knight aircraft) small production platform if you want "higher-performance" assist.

I agree that HTOL has a lot more "benign" abort options than VTOL but it tends to pretty much "even-out" if you design for engine-out situations. HTOL REALLY shines for lift-off mass IMHO since you don't HAVE to have a high thrust-to-weight if you have wings, but that harkens right back to a "carrier" aircraft versus plain-old launch assist concepts.

A thought has been going around in my brain over the Garvey NanoSat Launch Vehicle (http://www.garvspace.com/NLV.htm, http://www.garvspace.com/NLV_mockup.htm) and adding some "Jet-Pods" using Cruise-Missile/UAV jet engines to do small scale testing.

It would be a LOT cheaper than trying a full-scale, full-up program at any rate :)

Randy

I was not aware of that limitation of mass placement on the B1B though I figure it would need modifications anyway.
But I was thinking on making the LV part winged or a lifting shape anyway so the aircraft only sees the full mass at zero speed.
Sorta like like MAKS.
Of course it's probably best from a cost stand point to just settle for the largest and highest flying subsonic carrier you can afford.

In this case the best bang for the buck probably is the 747 modified in the same manner as the shuttle carrier.

The air launched sortie vehicle comes to mind.
http://www.thespacereview.com/article/1591/1

The tail mounted SSME in the 747 would not be needed with uprated engines.
« Last Edit: 05/27/2011 12:57 am by Patchouli »

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #17 on: 05/31/2011 07:46 pm »
I was not aware of that limitation of mass placement on the B1B though I figure it would need modifications anyway.
Most people tend to "assume" that an aircraft can "carry" it's max-load on a "center-line" basis but usually (and for various reasons) cargo-specific aircraft are the only ones that can do that. :)

On the other hand though I remain sceptical that anyone is going to manage to pry any B1Bs from the Air Force's hands :)
(Oh and of course the Russians would have to have all SORTS of assurances that it was 'de-milled' if anyone DID so the "usefulness" is questionable... Now if you ask the Russians for one of THEIR "B1" clones you might have a better chance :) )

Quote
But I was thinking on making the LV part winged or a lifting shape anyway so the aircraft only sees the full mass at zero speed.
Sorta like like MAKS.
Of course it's probably best from a cost stand point to just settle for the largest and highest flying subsonic carrier you can afford.

In this case the best bang for the buck probably is the 747 modified in the same manner as the shuttle carrier.
If you are going to have the LV contribute to overall lift then the wings have be rather huge to accomodate. This brings up drag problems, which will limit your carrier aircraft's maximum alititude and speed. Of course having a lifting LV means your seperation manuever is going to be a bit easier, but again the wings have to provide lift at high altitude AND for the highest mass of the LV.
Quote
The air launched sortie vehicle comes to mind.
http://www.thespacereview.com/article/1591/1

The tail mounted SSME in the 747 would not be needed with uprated engines.
YMMV, but as "I" look at it, IF you're going to go to that much trouble I'd dump the whole "carrier-aircraft" in favor of specific, high-performance vehicles that could be attached to a spaceplane and provide zero-to-Mach-3/6 service for the vehicle.

Similar to the NASA/Langley "SpaceJet" concept using a pair of "fly-back" dedicated (unmanned) vehicles that contain jet-engines and other equipment that you don't NEED on the spaceplane. (Such as heavy landing gear) Yes you are now designing and building "custom" aircraft but given enough "adapability" (which IS easier to do with aircraft than for rockets of any stripe) it's possible they could be used with more than one spaceplane design. Being smaller than a "carrier" aircraft there should be a pretty hefty cost savings involved if the design is kept simple and robust.

On the other hand if you're going towards the lowest intital and continuing costs the "off-the-shelf" (well it is modified but as noted once this is done it still can be used for "other" duties) 747 airframe is pretty much a winner hands down.

The major design-point is what do you want to GET from the air-breathing part of the launch system?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Carreidas 160

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Re: Jet Powered First Stage
« Reply #18 on: 08/10/2011 09:25 am »
Time to breathe in some new life in this thread.

I read an article the other day about a 3D-printed UAV that was designed and built in 7 days. Only 1.6m wingspan but consists of a handful of structural parts that can be snapped together without fasteners etc.

http://www.newscientist.com/article/dn20737-3d-printing-the-worlds-first-printed-plane.html?full=true

How easy would it be to do the same for a small (say 50cm diameter), jet powered 1st stage demonstrator?

I'm thinking "just" a log of 3d-printed plastic with 1 hole in the middle (holding a dummy 2nd stage rocket) and a couple of holes around it to house micro jet engines.

immediate design/test issues (thinking out loud):
- 3d CAD design: aerodynamics & loading testing
- 3d printing
- jet engines
- fuel tanks
- avionics, parachute
- release mechanism for dummy 2nd stage
- flight control

Offline Jim

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Re: Jet Powered First Stage
« Reply #19 on: 08/10/2011 12:14 pm »
what does 3D printing bring to the table?

It doesn't change the rocket equation or make the idea viable.

Offline Carreidas 160

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Re: Jet Powered First Stage
« Reply #20 on: 08/10/2011 12:57 pm »
what does 3D printing bring to the table?

It doesn't change the rocket equation or make the idea viable.

I do believe it has implications for reducing R&D cost & time budgets.

As for my pet project described above, I'm not interested in scaling it up (at least not yet). I just want to launch dummy 2nd stage from a jet powered 1st stage demonstrator. I believe 3D printing will enable me to do so in a cheap and fast way. This wasn't possible 10 years ago.

(edited)
« Last Edit: 08/10/2011 02:36 pm by Carreidas 160 »

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #21 on: 08/10/2011 02:58 pm »
what does 3D printing bring to the table?

It doesn't change the rocket equation or make the idea viable.
Cheaper, more durable, light weight structures for rockets or space-craft. (Geodesic "Space Frame" construction is lighter and much more robust than the standard "monocoque" construction. It's biggest limitation has always been that it was labor intensive and therefore expensive to build. 3D printing allows such methods as Geodetic to be used at a lower cost more compatable with, and competative too standard "iso-grid" construction.) Easier and cheaper prototyping ability such as Carreidas 160 is discussing.

A LOT of the advantages and benifits of 3D printing is that it is an additive rather than the a subtractive process. Typically an iso-grid structure is milled down from a larger piece of materials. In many cases a fraction of a second delay can ruin a piece by subtracting too much material and therefore weakining the overall strength of the section. Addititve on the other hand builds up the materials layer by layer, bonding and (usually) merging the substructure to create less "stressed" structures with higher inheirent strength and durability.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Jim

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Re: Jet Powered First Stage
« Reply #22 on: 08/10/2011 03:02 pm »
what does 3D printing bring to the table?

It doesn't change the rocket equation or make the idea viable.
Cheaper, more durable, light weight structures for rockets or space-craft. (Geodesic "Space Frame" construction is lighter and much more robust than the standard "monocoque" construction. It's biggest limitation has always been that it was labor intensive and therefore expensive to build. 3D printing allows such methods as Geodetic to be used at a lower cost more compatable with, and competative too standard "iso-grid" construction.) Easier and cheaper prototyping ability such as Carreidas 160 is discussing.

A LOT of the advantages and benifits of 3D printing is that it is an additive rather than the a subtractive process. Typically an iso-grid structure is milled down from a larger piece of materials. In many cases a fraction of a second delay can ruin a piece by subtracting too much material and therefore weakining the overall strength of the section. Addititve on the other hand builds up the materials layer by layer, bonding and (usually) merging the substructure to create less "stressed" structures with higher inheirent strength and durability.

Randy

I meant as it applies to Jet powered first stage.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #23 on: 08/10/2011 03:12 pm »
I meant as it applies to Jet powered first stage.
Cheaper prototyping then. And lighter, less expensive airframes for the jet-engines and systems.

The "Jet Powered First Stage" concept itself is viable as long as it's contributory towards lowering operations and standing costs. THAT of course is the biggest question though. 3D printing makes doing experiments cheaper and simpler and pushes the ability to DO that kind of experimenting down further towards mass-scale experimentation.

That's always a good thing in transportation :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Carreidas 160

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Re: Jet Powered First Stage
« Reply #24 on: 08/10/2011 03:43 pm »
I meant as it applies to Jet powered first stage.
Cheaper prototyping then. And lighter, less expensive airframes for the jet-engines and systems.

The "Jet Powered First Stage" concept itself is viable as long as it's contributory towards lowering operations and standing costs. THAT of course is the biggest question though. 3D printing makes doing experiments cheaper and simpler and pushes the ability to DO that kind of experimenting down further towards mass-scale experimentation.

That's always a good thing in transportation :)

Randy

Exactly. It lowers the cost of prototyping which is where most designs are validated.

I'm not sure if a small jet powered 1st stage scales well but my bet is that if the design works at 50cm diameter, both aerodynamically and structurally, it works at 100cm diameter with minor design modifications. I have a feeling that jet engines also scale pretty well in terms of T/W and ISP. (edit: assumption is the mother of all #*&!-ups so I'm going to do some research on that ASAP)
« Last Edit: 08/10/2011 03:45 pm by Carreidas 160 »

Offline Danderman

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Re: Jet Powered First Stage
« Reply #25 on: 08/10/2011 03:53 pm »
I still believe that the cheapest jet boosters would be simple existing fighter jet engines strapped onto a rocket, with small fuel tanks; all of these would be jettisoned after the stack topped max velocity that the engines could tolerate. The fuel tanks would be small.

None of this would be reusable, jet engines are cheap.

Put 3 of these on a Falcon 1E, and performance would be increased significantly at very low cost.




Offline RanulfC

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Re: Jet Powered First Stage
« Reply #26 on: 08/10/2011 03:54 pm »
Time to breathe in some new life in this thread.

http://www.newscientist.com/article/dn20737-3d-printing-the-worlds-first-printed-plane.html?full=true
Thanks I'd been looking over articles on that and I hadn't seen that one yet.
Quote
How easy would it be to do the same for a small (say 50cm diameter), jet powered 1st stage demonstrator?

I'm thinking "just" a log of 3d-printed plastic with 1 hole in the middle (holding a dummy 2nd stage rocket) and a couple of holes around it to house micro jet engines.
Eh, first and formost WHAT are you "demonstrating" and what kind of equipment are you going to use?

As an "example" here, the following is a web-page from the USMicro-Jets company website:
http://usmicrojetllc.thomasnet.com/viewitems/all-categories/gines-for-uavs-and-remotely-piloted-drone-aircraft?

Note the first three entries: The AT-180/280/and 450 models are considerd usable for "Remote Control Hobby Aircraft" and they are three to five inches in diameter and mass around three-to-five pounds. Max thrust is only 20-45lbs and prices run from 3500 to around 4800 dollars for the engine itself.

Here's another company (in Europe) that makes and sells RC hobby jet engines:
http://waoline.com/detente/hobby/HobbyTurbines.htm
(That one however keeps redirecting so try this hobby shop one)
http://www.jetmodelproducts.com/amt.htmu

And there are a few other companies around the net.

Number two is what type of flight profile and "launch" profile are you looking at duplicating? This comes under the WHY heading, why are you doing the demonstrations? What are you hoping to achieve?
Quote
immediate design/test issues (thinking out loud):
- 3d CAD design: aerodynamics & loading testing
- 3d printing
- jet engines
- fuel tanks
- avionics, parachute
- release mechanism for dummy 2nd stage
- flight control
A good start but I'd figure on answering the above first to get a good idea of what you're wanting the design to do THEN start designing :)
Quote
Exactly. It lowers the cost of prototyping which is where most designs are validated.

I'm not sure if a small jet powered 1st stage scales well but my bet is that if the design works at 50cm diameter, both aerodynamically and structurally, it works at 100cm diameter with minor design modifications. I have a feeling that jet engines also scale pretty well in terms of T/W and ISP. (edit: assumption is the mother of all #*&!-ups so I'm going to do some research on that ASAP)
See links above.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Jim

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Re: Jet Powered First Stage
« Reply #27 on: 08/10/2011 03:54 pm »

The "Jet Powered First Stage" concept itself is viable as long as it's contributory towards lowering operations and standing costs.

And for vertical launch it will do none of that.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #28 on: 08/10/2011 03:56 pm »
Oh, AND this "project" has a possible "prize" reward I might add :)

See:
http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=376

"Carmack 100kft Micro Prize


The Carmack 100kft Micro Prize
In discussions on the mailing list aRocket of the relative difficulty of launching a rocket to 100,000 feet, John Carmack established a $5,000 prize for the first person or group to reach that goal.

This page logs the rules set up for that competition, and archives the text of the emails that established the prize and its rules. If someone registers a launch attempt or wins the prize, that information will be recorded here as well.

The Rules:

The prize is $5000 USD, and has been augmented with a further $5000-$5500 by the people listed at the end of this page. The collection of the prize from each benefactor is up to the prize winner.
The launch attempt must be registered by a post to aRocket at least 30 days prior to the attempt, with the following information:
A reasonable description of the vehicle
The launch location
The launch date
The rocket must gain 100,000 feet from launch altitude using rocket propulsion.
The rocket must record a GPS serial log of the flight with at least one report above 100,000ft plus the launch altitude.
The rocket must be recovered essentially intact, the recovery system having functioned.
The rocket must be recovered within 24 hours of launch.
A report on the vehicle and operations must be made available on the web for posterity, with a level of quality suitable for publishing in a magazine. The report's author retains copyright.
Good video of at least the launch must be shared. Ideally video is captured of the entire flight to recovery, but this is not required.
If multiple stages are used, they must all be recovered successfully.
Armadillo Aerospace is disqualified from the competition.
The competition is judged by John Carmack."

Passed on by Randy :)
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Jim

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Re: Jet Powered First Stage
« Reply #29 on: 08/10/2011 03:58 pm »

The rocket must gain 100,000 feet from launch altitude using rocket propulsion.

It fails this requirement.

Offline Carreidas 160

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Re: Jet Powered First Stage
« Reply #30 on: 08/10/2011 05:04 pm »
Eh, first and formost WHAT are you "demonstrating" and what kind of equipment are you going to use?

[...]

Number two is what type of flight profile and "launch" profile are you looking at duplicating? This comes under the WHY heading, why are you doing the demonstrations? What are you hoping to achieve?

Practically this is what I have in mind for my demonstrator:
1) WHAT:
  a) vertical launch demonstration of jet powered 1st stage
  b) release of dummy payload at reasonable altitude (and at upward velocity > 0)
  c) parachute descent of both 1st stage and dummy payload
2) WHY:
  a) validate concept of jet powered 1st stage
  b) establishing iterative 3d design/manufacturing/development process
  c) gather data to be used for development of bigger version

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #31 on: 08/10/2011 06:49 pm »

The rocket must gain 100,000 feet from launch altitude using rocket propulsion.

It fails this requirement.
"It" does not, but then again "it" ain't built yet ;)

Jim you're not paying attention to the big-picture here, there are going to be a couple teams who are looking at Rock-Oon type launches so launch from altitude isn't an "issue" at all. The "rocket" has to be capable of flying to an altitude of 100K feet from where-ever it's launched from. Be that the ground or 100,000ft.

"It" can't "fail" since "it" hasn't been designed or built or tested.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #32 on: 08/10/2011 07:06 pm »
Eh, first and formost WHAT are you "demonstrating" and what kind of equipment are you going to use?

[...]

Number two is what type of flight profile and "launch" profile are you looking at duplicating? This comes under the WHY heading, why are you doing the demonstrations? What are you hoping to achieve?

Practically this is what I have in mind for my demonstrator:
1) WHAT:
  a) vertical launch demonstration of jet powered 1st stage
  b) release of dummy payload at reasonable altitude (and at upward velocity > 0)
  c) parachute descent of both 1st stage and dummy payload
2) WHY:
  a) validate concept of jet powered 1st stage
  b) establishing iterative 3d design/manufacturing/development process
  c) gather data to be used for development of bigger version
Ok simple enough. First part is desiging a Vertical Take off first stage capable of carrying and releasing the "dummy" second stage. Luckily that doesn't even have to be "jet-powered" at this point in the game.

Ok you state you want to "release" the second stage payload at a "reasonable" altittude and a speed of more than "zero" relative to the "stage" I suppose?

Start with an "air-charge" either a simple piston and spring or a CO2 cartridge ejection system. Model a "simplified" first stage using quad-hex-tri-copter set up for initial testing since it's a cheaper alternative.

Things to work on would be take off and flight angle control(s) and stage seperation mechanics.

Question? Why parachute landing for the first stage? In general it would probably be better to baseline vertical landing, the fuel mass won't be that much.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Jim

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Re: Jet Powered First Stage
« Reply #33 on: 08/10/2011 11:33 pm »

The rocket must gain 100,000 feet from launch altitude using rocket propulsion.

It fails this requirement.
"It" does not, but then again "it" ain't built yet ;)

Jim you're not paying attention to the big-picture here, there are going to be a couple teams who are looking at Rock-Oon type launches so launch from altitude isn't an "issue" at all. The "rocket" has to be capable of flying to an altitude of 100K feet from where-ever it's launched from. Be that the ground or 100,000ft.

"It" can't "fail" since "it" hasn't been designed or built or tested.

Randy

a launch vehicle with a jet Powered First Stage fails the requirements of contest, since it is not a rocket powered first stage.

I would say the same goes for a Rocketoon, since balloons are "launched" and therefore the first stage is the balloon.

So you are going to come back with the response that its doesn't matter what the first stage is, as long as the second stage flies 100k ft from separation?  That isn't big picture, that is not following the spirit of the contest. 

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #34 on: 08/11/2011 04:16 am »

The rocket must gain 100,000 feet from launch altitude using rocket propulsion.

It fails this requirement.
"It" does not, but then again "it" ain't built yet ;)

Jim you're not paying attention to the big-picture here, there are going to be a couple teams who are looking at Rock-Oon type launches so launch from altitude isn't an "issue" at all. The "rocket" has to be capable of flying to an altitude of 100K feet from where-ever it's launched from. Be that the ground or 100,000ft.

"It" can't "fail" since "it" hasn't been designed or built or tested.

Randy

a launch vehicle with a jet Powered First Stage fails the requirements of contest, since it is not a rocket powered first stage.

I would say the same goes for a Rocketoon, since balloons are "launched" and therefore the first stage is the balloon.

So you are going to come back with the response that its doesn't matter what the first stage is, as long as the second stage flies 100k ft from separation?  That isn't big picture, that is not following the spirit of the contest. 
Read the rules Jim, actually it IS in the "spirit" of the contest by Carmack's own admission. AKA he approved, his real concern/goal is a viable and good accounting of HOW the job is done open and available to all. As long as the rocket powered portion does 100Kft on its own and all other conditions are met he's not limiting anything else.

His original reasoning was pretty simple, way to many folks hitting the ARocket list with off-hand comments about rocket powered flight to 100Kft being "easy", "simple" and "no-real-challenge" so he posted the prize to encourage "put-up-or-shut-up" and not surprisingly it seems a majority has "shut-up" rather than put up.

Your still going to need a heck of a rocket for the basic "100Kft" portion of the flight no matter what else and recovery isn't as simple as most people think so it's not like technical work and some serious thinking isn't going to be needed. "I'm" only pointing it out because it's a possible way to gain some money back AND some press IF one wants to go that route.

I fully expect that the prize will probably be won already by the time the proposed concept here is ready to fly, but just in case...

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Carreidas 160

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Re: Jet Powered First Stage
« Reply #35 on: 08/11/2011 11:24 am »
Ok simple enough. First part is desiging a Vertical Take off first stage capable of carrying and releasing the "dummy" second stage. Luckily that doesn't even have to be "jet-powered" at this point in the game.

Thanks Randy for your comments!

The Parrot AR.Drone comes to mind... http://www.parrot.com/usa/

I wonder how high it goes and what kind of payload it can carry. This one has a missile launcher mounted to its hull (too much pyrotechnics to my liking :) http://dronehacks.com/2011/06/09/ar-drone-7-missile-rocket-launcher/

Ok you state you want to "release" the second stage payload at a "reasonable" altittude and a speed of more than "zero" relative to the "stage" I suppose?

Both relative to the stage and relative to the earth's surface. I.e. such that v2 > v1 > 0, where v2 = second stage vertical velocity, v1 = 1st stage vertical velocity, at the moment of separation.

Start with an "air-charge" either a simple piston and spring or a CO2 cartridge ejection system. Model a "simplified" first stage using quad-hex-tri-copter set up for initial testing since it's a cheaper alternative.

This is where the parrot drone comes in.

Things to work on would be take off and flight angle control(s) and stage seperation mechanics.

Staging at altitude, at velocity, at an angle is where things get murky I guess.

Question? Why parachute landing for the first stage? In general it would probably be better to baseline vertical landing, the fuel mass won't be that much.

True. I guess parachutes on 2nd stage is something for later because I wonder if a full-scale jet powered 1st stage is able to return to earth on jet power alone. The jets would have to produce thrust at high negative airspeed at high altitude, I don't know if that is possible. It might need a chute of some kind, or braking rockets.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #36 on: 08/11/2011 01:56 pm »
Ok simple enough. First part is desiging a Vertical Take off first stage capable of carrying and releasing the "dummy" second stage. Luckily that doesn't even have to be "jet-powered" at this point in the game.

Thanks Randy for your comments!
Your welcome! Prepare to be overwhelmed ;)
Quote
The Parrot AR.Drone comes to mind... http://www.parrot.com/usa/
Well... Not really, probably more similar to this model:
http://www.draganfly.com/uav-helicopter/draganflyer-x6/

Though "home-built" and "DIY" (Do It Yourself) and RC-hobby versions are pretty sweet too!
Some examples:
“Overkill” Quad project
http://diydrones.com/profiles/blogs/operation-overkill-arducopter
Folding Hex-Rotor project
http://diydrones.com/profiles/blogs/hexarotor-folding-multirotor
(You might see a bit of a "trend" with my destinations, since I am seriously thinking about joining DIYDrones anyway :) )

QuadCopter on Wikipedia:
http://en.wikipedia.org/wiki/Quadrotor

RC Copter help Thread
http://www.rcgroups.com/forums/showthread.php?t=358497

Pretty much a general google search using the terms:multi-rotor, quad-rotor, hex-rotor, helicopter, DIY projects, information, (etc) will get you dozens of good articles and sites for various types of multi-rotor lifting platforms.

Quad/Hex/large-numbers-of-multiple-rotors/props is getting to be pretty popular from what I'm reading. The REALLY good news though is the amount of open-source and available control equipment that this has brought about.

Some pretty sophisticated autonomous and GPS systems are COTS, as is gyroscopes and stabilizer hardware AND (probably more important) software. Let me lay some links on you:

Here's Gyroscope system:
http://www.st.com/internet/analog/subclass/1288.jsp

Some open source Autopilots:
http://uavp.ch/moin/FrontPage
http://www.mikrokopter.de/ucwiki/MikroKopter?action=show&redirect=StartSeite

Some others:
http://www.opencircuits.com/Multi-rotor

http://www.himodel.com/radios/FY-91Q_Multi-rotor_Flight_Stabilization_&_Autopilot_System.html

http://www.dronesvision.com/feiyu-tech-fy-91q-dreamcatcher-navigation-edition-multirotor-flight-stabilization-autopilot-system/
There are multiple others around...

(Frankly the DIY-Drone/UAV/RC "model" stuff is getting a bit freaky. We've had a couple of techs have built a "garage" scale UAV that they are getting ready to unveil as cyber-attack drone: http://www.popsci.com/technology/article/2011-07/diy-uav-hacks-wi-fi-networks-cracks-passwords-and-poses-cell-phone-tower But hey, as I said before all this stuff is pushing the technology "down" to more people to play with :) )
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I wonder how high it goes and what kind of payload it can carry.
Probably not much and not to high but a lot of the "problem" with the "Parrot" is it's a simple toy, and it has a "draggy" design for VTVF operations. (The foam "body" would have to go :) )

Some of the "Heavy-Lift" versions I'm seeing can lift up to 5lbs or more, how high depends on where the rotor-blades/props lose effectiveness. (In most cases the general idea for these is not to let them get out of radio range, in our case that's going to be a given :) )
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This one has a missile launcher mounted to its hull (too much pyrotechnics to my liking :) http://dronehacks.com/2011/06/09/ar-drone-7-missile-rocket-launcher/
I'll have to access it at home, I'm at work right now :)

Most of these I've seen have launched the rockets horizontally, we are talking about launching the second stage vertically from the platform correct?

Ok you state you want to "release" the second stage payload at a "reasonable" altittude and a speed of more than "zero" relative to the "stage" I suppose?
Quote
Both relative to the stage and relative to the earth's surface. I.e. such that v2 > v1 > 0, where v2 = second stage vertical velocity, v1 = 1st stage vertical velocity, at the moment of separation.
Ok one thing at a time though :) I'd go for vertical velocity/altitude as the first parameter. See what kind of velocity we can get out of a simple prop/rotor powered lifting platform. The platform will have a high accelleration right off the ground to (some) altitude where the rotor/props begin to lose effectivness which is where you want to stage to retain the maximum delta-v assist.

Now not that we're going to have to worry about "max-q" at the moment one thing that I recall Carmack noting during testing of the Armadillo rocket(s) is that one of the more counterintuitive results has been that "taking-it-slow" deep in the atmosphere seems to yeild some interesting results for over-all delta-v mission wise. By NOT taking off at full thrust and pushing through Max-Q as soon as possible a lot of design and construction options are opened up that could lead to more flexible, robust, and easier to maintain general purpose launch vehicles.

Start with an "air-charge" either a simple piston and spring or a CO2 cartridge ejection system. Model a "simplified" first stage using quad-hex-tri-copter set up for initial testing since it's a cheaper alternative.

Actually I was thinking the piston/spring/air-charge for second stage seperation, but ya, the "parrot" works for some basic work and testing.

Initially for a "second" stage I'd recommend throwing together a simple paper model of a "Stomp-Rocket":
[url=http://paperstomprockets.com/html/___what_are_stomp_rockets_.html]http://paperstomprockets.com/html/___what_are_stomp_rockets_.html]
This is where the parrot drone comes in.
[/quote]
Actually I was thinking the piston/spring/air-charge for second stage seperation, but ya, the "parrot" works for some basic work and testing.

Initially for a "second" stage I'd recommend throwing together a simple paper model of a "Stomp-Rocket":
[url=http://paperstomprockets.com/html/___what_are_stomp_rockets_.html]http://paperstomprockets.com/html/___what_are_stomp_rockets_.html


Here are some build pages:
http://www.instructables.com/id/Paper-Stomp-Rockets-Easy-and-Fun/

http://www.eaa.org/chapters/resources/cookbook/activities/elementary/STOMP%20ROCKETS.pdf

http://www.afa.org/members/AENews/July10/Stomp%20Rocket%20Guide.pdf

Heck we can even "get-accurate" and show how to use something like this with "real" rockets :)
http://ecardmodels.com/product_info.php?products_id=1962
http://ecardmodels.com/product_info.php?products_id=1964?osCsid=01ae6eb7060ee7e0b188c4cdaa4bdbe1

(Saturn-V launch assist platform for the WIN! ;) )

The "launch-mechanism" would be a servo controlled "trigger" and a spring-and-piston resiviour. (Think "Nerf-Gun" :) )

Things to work on would be take off and flight angle control(s) and stage seperation mechanics.
Quote
Staging at altitude, at velocity, at an angle is where things get murky I guess.
Not that bad actually given various COTS equipment for RC-models, and high-powered hobby rocketry. Electronic, sensor, and GPS modules are available that can control and/or report those factors. We won't NEED it right away but we probably both need to come up with lists of specifications and lists of what is out there we can use or modify to see where this is at.

Question? Why parachute landing for the first stage? In general it would probably be better to baseline vertical landing, the fuel mass won't be that much.
Quote
True. I guess parachutes on 2nd stage is something for later because I wonder if a full-scale jet powered 1st stage is able to return to earth on jet power alone. The jets would have to produce thrust at high negative airspeed at high altitude, I don't know if that is possible. It might need a chute of some kind, or braking rockets.
Oh a parachute on the second stage isn't that hard to do, though the "paper-rockets" I pointed to above don't often use them because they are so light. We CAN actually incorperate a parachute if you want. But at first for ease of recovery I'd probably have a deployable streamer or some sort of drap mechanism.

Till we get to the point where we're launch some small model rockets from the platform we'll need a simple and "fool-proof" method to deploy the recovery system without hitting the lift-platform. One method is to have a "flap" section on the vehicle that is "biased" (light spring or folded bracing) that is "locked" until second stage launch. At this point the flap would be free to open if not for the air-pressure passing down the rocket. Once the rocket hits apogee, the flap opens and out pops the recovery device.

We currently shouldn't have to worry about the landing since the rotors/props shouldn't have much issue with "negative" air as we would probably have to leave them idealing for descent control.
Let me throw out the original JELAC (Jet Engine Launch Assist Concept) or POGO website again for information purposes:
http://home.earthlink.net/~altaccel/pogo/pogintro.htm

As I reall at least two jets were running the whole time including descent, I would assume the same for this idea as the jet engines would also be running your generators and/or hydralic pressure systems as in a normal aircraft.

We might want to look into an "emergency" recovery parachute depending on how much is spent on the prototype itself, but I suspect engine redundancy and alternate control methods will elminate the need for such eventually.

As for where to go from here, I'd suggest brain-storming the vehicle "set-up" for the intital test vehicle and buy a couple of multi-rotor toys to get a feel for what they can do. If you want to get the Parrot I'll look around locally and see what I can find here.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline mlorrey

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Re: Jet Powered First Stage
« Reply #37 on: 08/12/2011 02:40 am »
I would suggest the KISS principle when  invoking jet engines; use existing engines without modifications. Once you start adding requirements like flyback boosters, the whole concept sinks into a morass of unexpected constraints.


This is what parachutes and flotation devices are for.
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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #38 on: 08/15/2011 07:15 pm »
I would suggest the KISS principle when  invoking jet engines; use existing engines without modifications. Once you start adding requirements like flyback boosters, the whole concept sinks into a morass of unexpected constraints.


This is what parachutes and flotation devices are for.
Land recovery would be best, followed by air-recovery (mid-air recovery) since you want to keep the jets out of any contact with water if you can :)

Hugest issue for the pods is going to be intergration with existing LVs because you're not going to get as much "use" as you would by simply using expendable-solids such as the GEMs. With the jets you have to fly a bit more of a depressed trajectory and you end up with higher heating and aero-loads that current LVs aren't designed to handle. You can get around them, make some design changes but the question is really is the reuse and capabilities enough to convince LV makers to make the changes? Probably not, which means you're back to a specific design for an LV to use the jet-boosters or jet-assist in order to get the most operational benifits.

Of course IF you're going to go to all that trouble I could see attaching jet-boosters to something like this design:
http://www.rimworld.com/dsp/darquesol.html

:::::grin:::: ;)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Epis

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Re: Jet Powered First Stage
« Reply #39 on: 08/16/2011 06:57 am »
turbojet engines are good for airplanes (horizontal takeoff and landing).
for vertical takeoff first stage they just don't fit.
regarding recovery then only option in my mind as most economic is fly back capability. all other recovery options need more money and specially time for recovery (time = money) so for some reusable first stage hardware it must be fly back capable.
so in the end we get 2+1 option:
1. plane launch assist first stage like retrofitted blackbird Sr-71 drone plane which carry rocket inside it and release it at >30+km altitude and high Mach2-3 speed.
2. conventional rocket first stage, solid or liquid engine.
3. hypothetical high propulsion efficiency hybrid linear jet turbine/rocket engine for vertical takeoff and vertical landing fly back capable first rocket stage, with near vertical launch trajectory.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #40 on: 08/16/2011 08:49 pm »
turbojet engines are good for airplanes (horizontal takeoff and landing).
for vertical takeoff first stage they just don't fit.
If you think so you might not want to read the rest of this thread, on the other hand:
http://forum.nasaspaceflight.com/index.php?topic=25095.msg736430#msg736430

On the gripping-hand I'd point out that FINDING a "turbojet" these days is tough enough to do but they actually would be the best jet to use with thrust augmentation systems such as suggested. The majority of "jet" engines today are high-bypass tuboFANs and they generate their thrust by the bypass air, not the jet engine exhaust. Military turbofans such as fighter engines, (re: the P&W F100-200 suggested) are LOW bypass turbofan engines and generate the largest part of their thrust with the jet assembly. Moreso when "afterburner" or "reheat" is used.
Meanwhile in descending order of fuel efficency the list is turbofan (high-bypass), turbofan (low-bypass) and finally turbojet.

Commercial aircraft use high-bypass turbofans because fuel efficincy is more important than raw thrust during flight. Military aircraft need higher thrust ratios and therefore favor low-bypass turbofans, and earlier true turbojets. Since thrust-to-weight is important in the concept low-bypass surplus military jet engines are baselined.
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regarding recovery then only option in my mind as most economic is fly back capability. all other recovery options need more money and specially time for recovery (time = money) so for some reusable first stage hardware it must be fly back capable.
"Flyback" is only required if the booster(s) seperate at high speed and/or high altitude and far down-range. In the quoted concept the jet-boosters were recovered no within 40-80 miles of the launch site with a single heavy truck and crane and a four-person crew. Updating with steerable parafoils the engines could easily glide back to a recovery site near the launch site. Better would be to recover the pods in mid-air by helicopter rendevous and deliver to the maintenance site.

As to the "time" factor any rocket powered booster is going to require an extensive check out and maintenance routine. Meanwhile as long as the on-board engine sensors show no problems the jet-pods would need to have a new parafoil installed and they are ready for the next flight.

Your biggest "time" issues is going to be stage re-intergration with the next launch vehicle and fueling.

Quote
so in the end we get 2+1 option:
1. plane launch assist first stage like retrofitted blackbird Sr-71 drone plane which carry rocket inside it and release it at >30+km altitude and high Mach2-3 speed.
2. conventional rocket first stage, solid or liquid engine.
3. hypothetical high propulsion efficiency hybrid linear jet turbine/rocket engine for vertical takeoff and vertical landing fly back capable first rocket stage, with near vertical launch trajectory.
A supersonic carrier aircraft is going to be expensive to design and develop let alone operate. (The SR-71 and Concord are out as neither has the capability to be "re-purposed" enough to be useful without basiclly "re-building" the airframe from the ground up at great expense. A supersonic military bomber would have the same issues, but being "military" in the fist place makes operations costs automatically higher to begin with)

"Conventional" rockets have all the same issues as any other "rocket" vehicle with the high maintenance and operations cost associated with them currently. Jet engines as boosters while not as overall "effcient" as convetional solid or liquid engine boosters have the maintenace and operations history and proven ability that allow faster and more streamlined launch operations. IF the jet engines can be intergrated into the overall vehicle and operations design from the start.

There is no 'hypothetical' about the concept and no need for a "linear" or new design engine. Current low-bypass military surplus turbofan engines CAN do the job with current technology and no waiting. If you're going to comment on a message you MIGHT want to read the thread and understand what your commenting on first.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #41 on: 08/16/2011 09:06 pm »
I still believe that the cheapest jet boosters would be simple existing fighter jet engines strapped onto a rocket, with small fuel tanks; all of these would be jettisoned after the stack topped max velocity that the engines could tolerate. The fuel tanks would be small.

None of this would be reusable, jet engines are cheap.
Danderman: @$2-million dollars an "engine" for a recoverable "pod" was quoted by Pratt-&-Whitney for a F100-200 based engine to Dani Eder in the early '90s. The pod was 6000lbs fully ready for launch, and as noted here:
http://forum.nasaspaceflight.com/index.php?topic=25095.msg736430#msg736430 at least five (5) pods/engines would be needed to lift the Falcon-1E vehicle IF the F1E was redesigned to be able to use booster engines. Yes jets are "cheap" but recovery isn't a major operational or cost issue either.
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Put 3 of these on a Falcon 1E, and performance would be increased significantly at very low cost.
Since you brought it up :) ...

In order to use JELAC (Jet Engine Launch Assist Concept) on the Falcon-1E we'd first have to redesign the Falcon-1E.

So let me toss this out, (I'll need to take some time to get some numbers but as "food-for-thought" type BOE stuff...)

We take three (3) Falcon-1E first stages and place them inside a "aeroshell" structure using the second-stage and payload of two (2) of the Falcon-1Es as margin for the shell and support structure. (Why? Because the Falcon-1 isn't capable of "supporting" boosters as designed. The Aeroshell structure now takes all loads OFF the Falcon-1s and uses them simply as propellant tanks and ties the thrust structure together)

The aeroshell will be a "lifting-body" airfoil capable of using aerodynamic lift to augment the trajectory since the JELAC flight requires a depressed launch angle (90 degrees at launch to 35 degrees at staging) and contains all needed reentry and recovery gear for the two "booster" falcons. The third Falcon-1E is "cradled" recessed into the aeroshell of the booster and has a "Vacuum" Merlin instead of the Merlin-1C. All engines are started prior to lift off with the two booster Merlins and the core Merlin "throttled-down" as far as possible until the JELAC is staged.

Need to figure:
Total lift off mass
and
Number of JELAC units needed.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Epis

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Re: Jet Powered First Stage
« Reply #42 on: 08/17/2011 10:07 am »
there could be one special condition where vertical takeoff  jet engines could be useful and that is in heavy rainy day, or making artificial rain  1-2 km high virtual tunnel, so idea would be to deliver this additional water to Jet engines for ingestion as additional reaction mass, and also coolant, so engines could burn more fuel if cooled by large quantities of water so thrust to weight ratio could be increased till <1.7-2x  then if we have engine with max T/W of 9:1 (with afterburner running on full power) then by adding water we could get that figure probably to (<16-18):1
for real rocket vertical takeoff that could mean + <70-100% higher G vertical acceleration even for a short time period 10-15s at liftoff, will mean significant performance improvement because of rocket equation, gravity loss + engine efficiency improvement at ultra low speeds.
in real world example that would mean some sophisticated water spraying system development + special launch location as near cliff launch to increase virtual water/rain tunnel height. + calm weather condition with low wind speed be needed.

in the end to get most performance out of jet engine technology from such rain tunnel vertical takeoff new type of engines will be needed to develop. taking of the shelf used secondhand engines won't give highest performance possible.

Offline Carreidas 160

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Re: Jet Powered First Stage
« Reply #43 on: 08/17/2011 02:08 pm »
Ok simple enough. First part is desiging a Vertical Take off first stage capable of carrying and releasing the "dummy" second stage. Luckily that doesn't even have to be "jet-powered" at this point in the game.

Thanks Randy for your comments!
Your welcome! Prepare to be overwhelmed ;)

Lol, thanks again :) That's a lot of info...

In the meantime I went ahead and set up an account (Carreidas_160) at diydrones.com. Now need to find some money to fuel my new expensive hobby...

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #44 on: 08/17/2011 08:18 pm »
Ok simple enough. First part is desiging a Vertical Take off first stage capable of carrying and releasing the "dummy" second stage. Luckily that doesn't even have to be "jet-powered" at this point in the game.

Thanks Randy for your comments!
Your welcome! Prepare to be overwhelmed ;)

Lol, thanks again :) That's a lot of info...

In the meantime I went ahead and set up an account (Carreidas_160) at diydrones.com. Now need to find some money to fuel my new expensive hobby...
"Honest officer! I was mugged by a Drone!"
Hmmm.... Nahhh, probably not practical ::::grin:::: ;)

You're welcome, again, and yes it is :) As to the money issues, yep, you and me both...

One reason I'm looking pretty hard at the "skeletal" quad/hex-rotor vehicles is once you get some "intial" flight testing under your belt it wouldn't be that hard to wrap a home-made "duct" around the props which should increase your lift ability.... Which brings to mind a youtube video (can't find now :( ) of an RC plane with ducted fan engines that was rigged with a set of propane "afterburners" behind the fans.

Probably not much thrust but it was damn impressive :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #45 on: 08/17/2011 09:14 pm »
:::::facepalm::::: Ugh, did you even read the linked message?

there could be one special condition where vertical takeoff  jet engines could be useful and that is in heavy rainy day, or making artificial rain...
<serious-snip>
It's actually called "mass-injection" though it has the added benifit of cooling incoming air at higher speeds and increasing density. NO you don't need "rain" you actually carry water in the vehicle and INJECT it into the intake, and it can double the installed thrust (dry-and-wet) of a turbojet/turbofan engine. It was "standard" equipment and practice for early turbojets for added take off thrust.

The "latest" iteration was the Mass-Injection-Pre-Compressor-Cooling (MIPCC) concept which used both water and LOX injection to seriously increase the thrust-to-weight and Mach-envelope of a standard low-bypass-turbofan engine (the F-100-200) doubling the thrust output at all simulated altitudes and moving the maxium mach from Mach-2.4 to around Mach-5.

Your "idea" is far to complicated and requires to much investment in infrastructure to be practical. Worse it does nothing to "improve" performance when something far more simpler and cost-effective is already proven technology.
Quote
In the end to get most performance out of jet engine technology from such rain tunnel vertical takeoff new type of engines will be needed to develop. taking of the shelf used secondhand engines won't give highest performance possible.
Bleh, that's total BS because even with all the tweaks of adding water injection etc, a Low-Bypass Turbofan jet engine OUTPERFORMS a rocket engine from sea-level to around 40Kft and Mach-2... IF (super-large "if" by the way) "performance" is all you look at, which by the way "performance" is measured differently for air-breathing engines (and associated airframes) and rockets.

A "rocket" wants/needs to get off the pad and gain altitude as fast as possible in order to reduce the efficincy losses it suffers at low-altitude and speed. An air-breathing engine on the other hand also likes to accellerate but at a more shallow angle to maximize air-intake. A subtle but major difference that highly effects the "design" of the vehicle in question.

The "performance" and "efficincy" here that MATTERS isn't how fast the vehicle gets off the pad or a huge T/W advantage its the initial and operations costs over the flight duration and rate that comes out.

The "second-hand" jets cost around $2 million (1990's) dollars to procure and maybe $5,000.00-to-$10,000.00 dollars per hundred hours (hours please note, not minutes or seconds) of operation. Meanwhile about the same intial layout will buy you a GEM solid booster that can be used ONCE and then is discarded, which makes sense ONLY if your flight rate is low and "operational" costs of several millions dollars for single use, one time items is part of the "low-end" noise of operations.

High-performance equals high-costs and is never going to allow lower costs and frequent use, the exact opposite of what as successful commercial operation wants, or needs.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Epis

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Re: Jet Powered First Stage
« Reply #46 on: 08/18/2011 10:43 am »
after quick wiki search came to 2 water input types, one is injection and other ingestion.
first injection is for turbojet engines where relatively small quantities of water are injected in turbine for blade cooling, so this case is not what I had in mind, because water quantities are really small that could be added to improve thrust, but thrust improvements here comes from more fuel consumption rather than more added water reaction mass.

second is external ingestion, and this is mostly referred to turbofan engines like most airplane use where frontal big fan can handle huge quantities of water, there are videos in youtube where turbofan engines are tested and sprayed with high quantities of water, so basically all that water goes through first fan and bypasses central turbine. so this technology what i had in mind, where huge quantities of water could be used for thrust improvement.
for example if we would have 10 Ton rocket then flying through  1km long water tunnel at slow 5-10m/s2 vertical acceleration with turbofan propelled first stage could ingest more than 10 Tons of water, so basically that would be impossible to carry additional 10+ tons of water on board if such small power turbofan engines be used.
unknown variables are Max thrust and water flow rate that of the shelf turbofan engines can handle, if those numbers are large then idea could be real, but if they are small then that makes no sense.

so I am talking about how to increase jet powered first stage thrust at star up with same amount of fuel, not how to increase thrust by burning more fuel in afterburner by water/lox/ .. additional injection techniques. etc..

Your "idea" is far to complicated and requires to much investment in infrastructure to be practical. Worse it does nothing to "improve" performance when something far more simpler and cost-effective is already proven technology.
A "rocket" wants/needs to get off the pad and gain altitude as fast as possible in order to reduce the efficincy losses it suffers at low-altitude and speed. An air-breathing engine on the other hand also likes to accellerate but at a more shallow angle to maximize air-intake. A subtle but major difference that highly effects the "design" of the vehicle in question.

The "performance" and "efficincy" here that MATTERS isn't how fast the vehicle gets off the pad or a huge T/W advantage its the initial and operations costs over the flight duration and rate that comes out.

The "second-hand" jets cost around $2 million (1990's) dollars to procure and maybe $5,000.00-to-$10,000.00 dollars per hundred hours (hours please note, not minutes or seconds) of operation. Meanwhile about the same intial layout will buy you a GEM solid booster that can be used ONCE and then is discarded, which makes sense ONLY if your flight rate is low and "operational" costs of several millions dollars for single use, one time items is part of the "low-end" noise of operations.

High-performance equals high-costs and is never going to allow lower costs and frequent use, the exact opposite of what as successful commercial operation wants, or needs.

Randy

if you want to accelerate at a more shallow angle it would require more aerodynamic rocket / turbine first stage body so it will further complicate design, and stage separation will be more difficult at lower altitude/higher speed.
in the end you will get vertical launch Jet plane that Carry rocket so why not use conventional horizontal takeoff jet plane drone.

speaking about simplicity, reliability, then my final idea for launch assist techniques was linear turbine/rocket first stage that could be made ultra simple without any moving parts at all ! (except few valves) by using pressure fed low tech isp (150-200s ) rocket engines, few static turbine blades and rail infrastructure, its all low tech, i start to think that it is too low tech idea like solid rocket boosters for first stage to get some attention :(  .

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #47 on: 08/18/2011 03:29 pm »
after quick wiki search came to 2 water input types, one is injection and other ingestion.
You must have missed where I noted that it was specifically "injection" of water for thrust augmentation....
Quote
first injection is for turbojet engines where relatively small quantities of water are injected in turbine for blade cooling, so this case is not what I had in mind, because water quantities are really small that could be added to improve thrust, but thrust improvements here comes from more fuel consumption rather than more added water reaction mass.
Eh... that would be "no" since water injection was NOT used to "cool" the turbine blades but to "cool" the incoming air, making it denser and therefore pushing out more thrust.
Some explanitory links:
http://www.kls2.com/cgi-bin/arcfetch?db=sci.aeronautics.airliners&id=%[email protected]%3E

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092063_1993092063.pdf

http://aerade.cranfield.ac.uk/ara/1950/naca-report-981.pdf

While overall ISP suffers somewhat, operationally the MIPCC-Low-Bypass-Turbofan still beats out a pure rocket motor by a high margin from take-off to around 50-80Kft and Mach speeds of 1+.
Quote
second is external ingestion, and this is mostly referred to turbofan engines like most airplane use where frontal big fan can handle huge quantities of water, there are videos in youtube where turbofan engines are tested and sprayed with high quantities of water, so basically all that water goes through first fan and bypasses central turbine. so this technology what i had in mind, where huge quantities of water could be used for thrust improvement.
It doesn't increase thrust that much since the overall flow through the fan is already largly "denser" than that coming from the turbojet section of the engine. The High-Bypass turbofan is already optimized for low "turbine" section thrust and high density, low velocity air movement by the "fan" section.

The fact is that a High-Bypass turbofan benifits very little from water injection OR ingestion, while Low-Bypass turbofans get larger benifits and straight turbojets get the biggest boost of all. "Huge" quantities of water take "huge" amounts of equipment and cost money you don't want for no performance or operations gain. I suggest you broaden your "google" searches and learn more before you make assumptions.
Quote
for example if we would have 10 Ton rocket then flying through  1km long water tunnel at slow 5-10m/s2 vertical acceleration with turbofan propelled first stage could ingest more than 10 Tons of water, so basically that would be impossible to carry additional 10+ tons of water on board if such small power turbofan engines be used.
unknown variables are Max thrust and water flow rate that of the shelf turbofan engines can handle, if those numbers are large then idea could be real, but if they are small then that makes no sense.
There would be NO thrust increase because a high-bypass turbofan already is moving dense air at low velocity and "adding" water has no effect on this.

MIPCC/Thrust-Augmentation water is usually less than 1000lbs which is more than enough for 10 minutes or more of operation.
Quote
so I am talking about how to increase jet powered first stage thrust at star up with same amount of fuel, not how to increase thrust by burning more fuel in afterburner by water/lox/ .. additional injection techniques. etc..
Actually you are seeming to have misunderstood how the process works or even what the process is. Afterburning DOES burn more fuel for a higher thrust level, but this is well within standard practice and is a well known process. For under two minutes of flight time fuel consumption is practical and would use between 1000lbs to 2000lbs of jet fuel per engine per flight.

I mentioned LOX injection because that is included in most MIPCC concepts of late but it is ONLY used to stabilize the combuster flame at high altitude and not normally suggested for use in a first stage. (There is a suggested method of using LOX injection in the afterburner section to allow it to become a type of rocket engine but that is beyond the scope of this initial concept phase)

Read the above references and once you understand how and why water injection actually works you will understand it in context of this dicussion.

Quote
if you want to accelerate at a more shallow angle it would require more aerodynamic rocket / turbine first stage body so it will further complicate design, and stage separation will be more difficult at lower altitude/higher speed.
in the end you will get vertical launch Jet plane that Carry rocket so why not use conventional horizontal takeoff jet plane drone.
By taking off vertically you are no longer constrained by under-carriage/lower-aircraft-hull and runway seperation distances. Secondly the majority of "redesign" needed in most cases is some structural reinforcment for the overall rocket and a new design fairing for the aerodynamic heating and loading.

Staging is a question of design and intent, the original concept used detachable jet "pods" using simple but robust aircraft-weapons attachment systems. The later mentioned "POGO" JELAC vehicle was an intergrated vehicle with jet engines that carried it's rocket stage(s) either on the vehicle nose as other booster stages or in a semi-recessed conformal carry configuration.

The Jet-Pod JELAC staging was simply releasing the attachment hardware and falling away in the same manner as booster-SRMs/GEMs do since the core rocket had been lit at lift off and simply throttle-up as the pods dropped away. In the POGO case the nose attachment would have required and engine-start event just prior to staging, then the POGO jets would throttle down to enhance seperation. In the Semi-Recessed configuration the liquid second stage engine is exposed and starts prior to lift off and is throttled back until staging where it throttles up and the POGO engines again throttle down.

All staging events take place at 50Kft or higher and around Mach-2 for the "basic" designs, enhanced designs (such as those using MIPCC) can stage at Mach-4+ and altitudes over 80Kft. The Mach-2/50Kft version allows the use of off the shelf engines and simple inlet design with minimum need for aerodynamic optimization of the rocket stages while the higher performance system requires more attention to aerodynamic interaction between booster and rocket.
Quote
speaking about simplicity, reliability, then my final idea for launch assist techniques was linear turbine/rocket first stage that could be made ultra simple without any moving parts at all ! (except few valves) by using pressure fed low tech isp (150-200s ) rocket engines, few static turbine blades and rail infrastructure, its all low tech, i start to think that it is too low tech idea like solid rocket boosters for first stage to get some attention :(  .
While the linear turbine/rocket MIGHT be "low-tech" has anyone actually built a flying model? Low-pressure fed rockets are low-tech but for that very reason they don't tend to perform well. The static turbine and rail "infrastructure" is part of the problem though, it's an "up-front" investment that is hard to justify unless you already have a "need" for it and a viable market. Which is not the case at the moment.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Epis

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Re: Jet Powered First Stage
« Reply #48 on: 08/19/2011 04:34 pm »
I understand now that this water ingestion idea won't work for turbofan engines. so I am dropping off this idea.
whats left ?
only thing that is left is some kind of mechanical launch assist catapult style launch for that jet powered first stage in order to lower needed Jet engine thrust requirements.
if X is whole rocket weight then we could reduce Max possible Jet engine thrust by some 0.5x out of 1.5x that normally would be Ok for 1.5G (real 5m/ss) acceleration so now we talk about 1X jet engine max thrust that means   0 m/ss vertical acceleration, but 1G acceleration of craft, so that would mean engines would have power to combat earth gravity, but not to make some vertical acceleration, in vertical launch assist case it could be OK if rocket is accelerated to some >100-150 m/s vertical speed then firing Jet engines  could hold or decrease that vertical  climbing speed increasing fast horizontal speed to start flying like plane.

so basically if your idea needed 3 large Jet engines for rocket vertical launch assist than by using small short catapult tower you could reduce engine count down to just 2 engines + would need 1/3 less fuel to carry with you, or with same amount of fuel would reach higher altitude and speed.

only disadvantage is as always large infrastructural investments in catapult 0 stage launch assist.
so at the end if you wont to fly wingless, landing gear less, vertical takeoff jet powered rocket that would use all benefits of jet engine high propulsion  efficiency then you need something that will get it off the ground and give it initial speed boost.
instead of vertical catapult, rocket sled track could be second option, basically there are lot of options how to make that push, or use old good solid rocket boosters to add missing 0.5X thrust for short period of time like 15-20s for initial boost.
in the end cheapest version would be:
solid rocket booster assisted Jet powered fly back capable first rocket stage :D

Quote
While the linear turbine/rocket MIGHT be "low-tech" has anyone actually built a flying model?
I cant find any reference of somebody trying to build linear turbine engines, in real. Even in simplest forms like pressure fed rocket powered, just patents and concepts exist but most of them are for civil use like running trains, nothing for rockets. so this is brand new field of exploration.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #49 on: 08/20/2011 01:41 am »
I understand now that this water ingestion idea won't work for turbofan engines. so I am dropping off this idea.
I didn't say it wouldn't work, quite the opposite in fact. It's your grand "sprayed-water-tunnel" concept I was pointing too....
Quote
whats left ?
only thing that is left is some kind of mechanical launch assist catapult style launch for that jet powered first stage in order to lower needed Jet engine thrust requirements.
Again, not even close but I somehow don't think you're even reading what I'm writing at this point. Still...

This blog entry entitled: "Catapult Gain" specifically address methods for tossing a Falcon-1 into the air. You might want to read up on it...
http://ambivalentengineer.blogspot.com/2006/02/catapult-gain.html
*NOTE* I'm again going to point out that ANY such "launch-assist" for a Falcon-1 LV is going to take design changes and 'beefing-up' of the Falcon-1 because at the moment it can't handle any "launch-assist" forces due to its construction. Anyone taking a look at these and other "concepts" or suggesting such needs to keep that in mind :)

Overall you keep missing the point that by-themselves off-the-shelf low-bypass turbofan engines currently available are perfectly capable of doing the "launch-assist" job without a need for massive infrastructure building or excessive costs.

Such engines have enough excess thrust to perform the job, and are cost effective enough to be used should anyone actually decide they want to invest the effort and money into the concept. Either as drop-off "pods" or integrated into a vehicle booster unit currently affordable, efficient, capable, and available jet engines could be boosting upper stages towards orbit a few years after initial investment in the concept.

But since you'd rather not face reality.... 

Quote from: RanulfC
While the linear turbine/rocket MIGHT be "low-tech" has anyone actually built a flying model?
Quote
I cant find any reference of somebody trying to build linear turbine engines, in real. Even in simplest forms like pressure fed rocket powered, just patents and concepts exist but most of them are for civil use like running trains, nothing for rockets. so this is brand new field of exploration.
My point exactly. It is NEW tech that has yet to be developed to the point of being flight test-able. Therefore it is GOING to cost more and be longer getting into operation than if one simply used what IS available and  currently off-the-shelf.

IF you wanted to use "higher-performance" air-breathing engines there ARE actually about a dozen different engine cycles that have at least been bench/laboratory/high-speed-wind-tunnel tested to the point of being ready for flight-testing. However, it should be noted that such engines require much MORE than just some simple "vehicle-redesigns" to allow the use of current rocket stages. In most cases they actually require a fully integrated and aerodynamically interactive "vehicle" for operations.
Examples would be:
Air-Turbo-Rocket, (ATR) a good background blog for this concept engine is here: http://plasmawind.typepad.com/

Ejector-Ramjet/Supercharged-Ejector-Ramjet, (ERJ, SERJ) which is a type of "Air-Augmented-Rocket" engine using a fuel rich rocket exhaust to entrain air into a duct for augmentation. (In the case of the SERJ a "fan" is added run by exhaust turning a turbine similar to the ATR concept above to seriously enhance the ERJ air intake)
Information can be found here:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000091010_2000125932.pdf
http://settlement.arc.nasa.gov/Nowicki/SPBI104.HTM

Ram-Rocket:
http://caius.utias.utoronto.ca/rbcc.html

And the various members of the simple "Ducted" or "Air-Augmented" rocket family, including the solid, hybrid, and liquid rocket engine systems and associated mixing/burner duct assemblies:
http://science.ksc.nasa.gov/shuttle/nexgen/OEPSS_Reports_a/OEPSS%252010-Air%2520Aug%2520Rocket.pdf
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADB121965&Location=U2&doc=GetTRDoc.pdf
http://gltrs.grc.nasa.gov/reports/1997/TM-107422.pdf

and of course searching for anything on "combined-cycle" propulsion systems will usually give plenty of material.

But as always, "your-mileage-may-vary" (usually quite a bit from mine but that is probably a "nit" at this point :) ) so have fun...

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Epis

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Re: Jet Powered First Stage
« Reply #50 on: 08/21/2011 10:07 pm »
Quote
Again, not even close but I somehow don't think you're even reading what I'm writing at this point. Still...
I read everything !  just don't have any comments on your original Idea as it is, because if that was so simple then why there aren't lot of private space companys that make such vertical jet powered first stages ?

 
Quote
Air-Turbo-Rocket, (ATR) a good background blog for this concept engine is here: http://plasmawind.typepad.com/

Ejector-Ramjet/Supercharged-Ejector-Ramjet, (ERJ, SERJ) which is a type of "Air-Augmented-Rocket" engine using a fuel rich rocket exhaust to entrain air into a duct for augmentation. (In the case of the SERJ a "fan" is added run by exhaust turning a turbine similar to the ATR concept above to seriously enhance the ERJ air intake)
Information can be found here:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20000091010_2000125932.pdf
http://settlement.arc.nasa.gov/Nowicki/SPBI104.HTM

Ram-Rocket:
http://caius.utias.utoronto.ca/rbcc.html

And the various members of the simple "Ducted" or "Air-Augmented" rocket family, including the solid, hybrid, and liquid rocket engine systems and associated mixing/burner duct assemblies:
http://science.ksc.nasa.gov/shuttle/nexgen/OEPSS_Reports_a/OEPSS%252010-Air%2520Aug%2520Rocket.pdf
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADB121965&Location=U2&doc=GetTRDoc.pdf
http://gltrs.grc.nasa.gov/reports/1997/TM-107422.pdf


so whats a problem with all those concepts that.
1. limited operation range (earth atmosphere for air breathing engines)
2. limited operation speed.
3. if engine is dual operation mode (skylone and other jet rocket hybrids)
then they have pure performance in second operation mode, because of dead weight that need to be carried form first operation mode.
4. super high complexity, enormous part count, multiple points of failure.

so what would be dream engine ?
1. it will be dual operation mode, for low speed and for high speed operation.
2. it will perform in each operation mode like best in that mode engine can perform.  so if we have rocket operation mode I would expect T/w ration as high as good rocket engines have like > 70:1 if its turbo Jet mode then I expect high energy efficiency at low speed and T/w better than > 9:1
3. simplicity: low part count, no of few moving parts. low points of failure.

some time ago I searched all these hybrid engine concepts that you mentioned and each had its own problems, why they aren't good enough for real cost effective usage. so I am trying to think out of the box, in places where no one has searched before, mostly in unique set of conditions like 0 m/s wind speed for perfect weather conditions, mountain top, vertical tunnels, etc   and latest unexplored corner I came on was linear turbine engines so I started to think what possibilities could that offer ?  and it turned out it can offer unique dual operation mode engine possibility with unseen flexibility to drop off first operation mode turbine blades for pure high performance rocket mode.
so this unique flexibility drown my attention.  and its really cool tech, its like real transformer on the fly engine, at least it could be built like that.

there are 2 ways how technology is developing, one is incremental improvements, like better materials, more optimized design, so small improvements are made year by year. Second is new technology development that will outperform old one if not at first prototypes then  theoretically will have that capability bases on lows of physics, this is rocket field case, where rocket engines are on the top of what they can do, so each investment will yield less and less % improvement, so there will be a point were it will be meaningless to invest/invent .
latest leap in rocket engine tech was in 1980s, when was developed that  RD-170 from wiki http://en.wikipedia.org/wiki/NPO_Energomash
so 40 years have passed and how much improvement was made since then in performance figures of lox/kerosene engines ?
so we need new ways for rocket launching to increase energy efficiency of rocket launch.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #51 on: 08/30/2011 03:07 pm »
Quote
Again, not even close but I somehow don't think you're even reading what I'm writing at this point. Still...
I read everything !  just don't have any comments on your original Idea as it is, because if that was so simple then why there aren't lot of private space companys that make such vertical jet powered first stages ?
Noted way back at the begining of the thread was the fact that cheap launch operations are currently NOT a factor in launch costs enough to justify their use. And there is also a pretty strong bias against "air-breathing" in general in any of it's various forms.

Note also that the "orginal" idea wasn't "mine" either and that the original intent wasn't to simply propose a new launch system but to examine the MINIMUM captial (up-front) costs for a highly affordable, highly operable, and fully resusable launch system capable of putting around 6,000lbs into LEO. So far I've seen people critic the jets, the rockets, the concept, and the idea of a low cost launch system but so far I've not seen anyone actually examine or refute the basic economics and/or the captial costs themselves.

Quote
so whats a problem with all those concepts that.
1. limited operation range (earth atmosphere for air breathing engines)
2. limited operation speed.
3. if engine is dual operation mode (skylone and other jet rocket hybrids)
then they have pure performance in second operation mode, because of dead weight that need to be carried form first operation mode.
4. super high complexity, enormous part count, multiple points of failure.
The "problem" with any of these designs (every engine cited has been tested and refined design to a level capable of being flight tested, and in most cases they have been) is simply the "fact" that since "no-one" uses them currently and in most cases the technology as well as the main research on them was carried out and "shelved" in the 1960s then they must not "work" right?

Or why isn't "everyone" using them today? Simple, but fasle "logic" of course but it is an endemic attitude.
As evidenced by your list of "problems" for the cited engine cycles, none of which are "problems" at all.

I understand that you want to THINK you are thinking "outside-the-box" but in actuality all your doing is repeatedly trying to attach a "new-box" to every concept on these boards without regard to cost, complexity, and operability.

The "linear-turbine-engine" looks nice, but it really ONLY fits your premised concept of every launch system "needing" a "mountain-top, vertical-tunnel, external-accelerator" system as a basic requirment, which in and of itself "fails" for every single "problem" you previously listed!

There is no NEED of a "dream-engine" for cost effective space launch, nor new and costly techniques or technology. There IS a need for cost effective operations and planning so that routine launch operations are more comparable to standard "port" operations than the currently overblown and expensive circus' that they are.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Epis

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Re: Jet Powered First Stage
« Reply #52 on: 09/06/2011 11:10 am »
The "linear-turbine-engine" looks nice, but it really ONLY fits your premised concept of every launch system "needing" a "mountain-top, vertical-tunnel, external-accelerator" system as a basic requirment, which in and of itself "fails" for every single "problem" you previously listed!

There is no NEED of a "dream-engine" for cost effective space launch, nor new and costly techniques or technology. There IS a need for cost effective operations and planning so that routine launch operations are more comparable to standard "port" operations than the currently overblown and expensive circus' that they are.

Randy
the problem with your cost effective operations and planning that would make launch as often as airplane launch 1-2 per day is that there is no market for that, at least not now. its sort of chicken and egg question.
actually we can compare this situation with history of cargo transportation ships VS planes. where planes are fast traveling, super complex machines that could make multiple flights compared to ship that travels slowly but is super Low tech compared to plane and delivers in one trip thousand times more cargo. so which come first plane or ship ?
of course that was ship, long before planes appeared, so ships was main economic, progress  driver and developed all trading markets plotted ground to planes and passenger business, and then planes appeared, and still most of the cargo is shipped.
So is space LEO industry different ??
 I mean what must be first large heavy cargo capable rockets (ships) or small cargo multiple time reusable SSTO plane/rocket hybrids (skylone style)  ??
answer is simple its heavy cargo delivery ships that we need in space not planes to build all infrastructure and when that will be in place passengers could start to travel day by day basis and that is what skylone  style craft could do and your jet powered first stage concepts. but its all after heavy lift payload capacity rockets.
This is why every launch system I think off  "needing" a "mountain-top, vertical-tunnel, external-accelerator" because those have good scalability to extreme  payload sizes I could compare that to tanker ships Vs planes. 
my latest linear rocket turbine engine is one example of simplicity and high scalability to large sizes that could use existing decommissioned mining deep vertical shaft infrastructure (>20m Diameter)  1-2km deep and it would need to add turbine rails, and you could launch heavy rockets of the shelf and boost its payload capacity 2x-3X times compared to rocket without launch assist.
for example if Falcon heavy could launch 50 tons then if launched by tunnel linear rocket turbine assist it could launch 100-150 tons with same engine power/ count but additional structural reinforcement.

lets continue about ship/plane comparison to space transport.
so why we need launch assist ground based, rocket propelled infrastructure instead of airplane launch assist technology.
reason of course is scalability and nature of launch market that need large payloads several times in year till monthly launch its similar to intercontinental ship shipping times than airplane fast delivery service.
so Max will be few time in month. and when launch price will decline payload size will increase really fast and need for heavier payload LEO capable rockets will increase fast, we can see that already in manned mars mission, moon base ideas, and etc. so heavy lift is what is needed.

so if we speak about heavy lift rocket then Jet engines drop out of question really fast because of available engine size and dimensions.  for example one of the biggest Jet engine is BE90-115B  that delivers 55.7 Ton thrust compare that to biggest rocket engine RD-170 that makes 788.7 Tons of thrust  difference is large more than 14X in thrust so now chance that jet engines will take place of rocket engines any time soon.
so its obvious that space tanker ships (heavy lift rockets) must use rocket engines in order to reach larger and larger lift payload capacity. and launch assist tunnel, mountain slope can instantly improve that payload to LEO figure more than 2-3X using existing engine size and tech.

Most important thing is Time to market of how fast tech can be built and go to operation today it is no more than 4-5 years, this argument was mentioned in one of recent space conference online videos were future of space projects was discussed after shuttle retire, and funding was a main uncertainty of long term projects >10 years. so to make something real you need to make it as fast as possible that means no new fancy complex technology that needs long Research and development, certification, testing times and so on.  so for real business tech must be as simple as possible on well known tech  and industry.
all investments in launch assist tunnel style infrastructure will fast pay back itself specially if using existing mining industry shafts and etc industry.  as counter argument against large infrastructure investments in vertical launch assist I can say that there must be more mining shafts drilled to suit vertical launch assist  in the world than airplane runways capable for skylone size craft takeoff. :)  and as in airplane ports, mining sites has all infrastructure necessary for basic operations in place ( rods, some has even railroads, power lines etc.). just go buy used mine and retrofit for rocket launch assist.  some mines are in hard to reach places at high altitude 4-5Km + that could be beneficial for rocket launch.

Offline mlorrey

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Re: Jet Powered First Stage
« Reply #53 on: 09/07/2011 08:33 am »
Quote
Again, not even close but I somehow don't think you're even reading what I'm writing at this point. Still...
I read everything !  just don't have any comments on your original Idea as it is, because if that was so simple then why there aren't lot of private space companys that make such vertical jet powered first stages ?

Rocket people arent jet engine people. Rocket people come from the missile community and generally think of launchers as expendable ammunition. Jet engine people value sortie rates as much as other performance parameters because you dont throw airplanes away, its an entirely different econometric model.

Ammunition people see the way to make money is to make lots of ammunition and sell them one bullet or rocket at a time for as high a price as you can get. Jet engine people see the way to make money is to build one great airplane model and fly as many possible flights with that one plane, carrying as much cargo/passengers as possible before the wings and engines wear out.

To rocket people, most of them at least, the idea of a reusable launch vehicle is as stupid as Detroit thought of the idea of a car that gets 100 mpg and lasts 1 million miles (remember how in the 1960's Detroit pushed the idea of "planned obsolescence" so that your car would wear out exactly when they needed to sell you a new car to keep their business operating). If an idea doesnt work within your existing business model, you are more likely to downplay and fight against it.
« Last Edit: 09/07/2011 08:34 am by mlorrey »
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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #54 on: 09/07/2011 06:51 pm »
the problem with your cost effective operations and planning that would make launch as often as airplane launch 1-2 per day is that there is no market for that, at least not now. its sort of chicken and egg question.
A serious "point" vis-a-vis ANY of the various proposals and concepts for lower cost and higher use systems discussed here :)

Quote
actually we can compare this situation with history of cargo transportation ships VS planes. where planes are fast traveling, super complex machines that could make multiple flights compared to ship that travels slowly but is super Low tech compared to plane and delivers in one trip thousand times more cargo. so which come first plane or ship ?
of course that was ship, long before planes appeared, so ships was main economic, progress  driver and developed all trading markets plotted ground to planes and passenger business, and then planes appeared, and still most of the cargo is shipped.
So is space LEO industry different ??
Actually YES LEO 'industry' is different, VASTLY different. The analogy of Earth transportation with space transportation simply fails because of the numerous and vast differences between even the most simple transportation systems capable of delivering payload to Orbit and the conditions and requirements which have no analog withing Earth transportation systems.

Direct comparisions just don't work.

Spacecraft are NOT ships, planes, trains or trucks and that's something we have to live with.

The current paradigm will continue to hold unless and until it has been "proven" wrong by demonstrating otherwise. So far any studies done on the subject clearly show that reusablity along with more "cargo-and-passenger" freindly operations and a higher flight rates push access costs down significantly.
This assumes however an expanding market which fully utilizes the benifits offered by streamlined operations and reusabel vehicles.

If one takes a highly conservative approach and assumes that little increased market demand will appear and that the current paradigm of operations and vehicle development will not change significantly any time soon the "up-front" costs of development of reusable vehicles and streamlined operations can be seen to never be acceptable to pursue due to excessive funding requirements.

To re-phrase what Mlorry wrote; Rocket engine and spacecraft people tend to express their designs in seconds/minutes and at best hours. Jet and Aircraft people express their designs in minimums of Hours but most often years and decades. Spacecraft have to reach Aircraft levels of UTILITY even if they don't actually have "days" between maintenance and operations workloads.

Lastly let me say this about payload to orbit; while there may not be a great demand for "small" payloads to orbit of a couple of thousand pounds it is a very simple fact that once you PROVE you can deliver a few thousand pounds cheaply and reliably it suddenly becomes MUCH easier to convince people to invest in your developing and operating the capablity of orbit 10s of thousands of pounds.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Jim

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Re: Jet Powered First Stage
« Reply #55 on: 09/07/2011 07:21 pm »

Rocket people arent jet engine people. Rocket people come from the missile community and generally think of launchers as expendable ammunition. Jet engine people value sortie rates as much as other performance parameters because you dont throw airplanes away, its an entirely different econometric model.

Ammunition people see the way to make money is to make lots of ammunition and sell them one bullet or rocket at a time for as high a price as you can get. Jet engine people see the way to make money is to build one great airplane model and fly as many possible flights with that one plane, carrying as much cargo/passengers as possible before the wings and engines wear out.

To rocket people, most of them at least, the idea of a reusable launch vehicle is as stupid as Detroit thought of the idea of a car that gets 100 mpg and lasts 1 million miles (remember how in the 1960's Detroit pushed the idea of "planned obsolescence" so that your car would wear out exactly when they needed to sell you a new car to keep their business operating). If an idea doesnt work within your existing business model, you are more likely to downplay and fight against it.

bad analogy.  You don't know the people to make such a stereotype.

Offline Epis

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Re: Jet Powered First Stage
« Reply #56 on: 09/08/2011 09:12 am »
first your misconception in vertical launch assist rocket approach is that rocket stages will be unusable, reality will be  quite an opposite they could be made all multiple time usable fly back capable starting from first turbine rocket stage, till second LEO stage, its because launch assist can give so high LEO payload boost >2x (>5-6% of rocket Weight, some advanced long rail high G launch assist could deliver >10% ) than you could trade some payload capacity for re usability and structural integrity/ safety  etc. because rocket size by itself. (falcon 9 has 3.1% payload of rocket Weight and skylone on paper has ~4.3%)
If replacing first conventional rocket stage 2/3X of all rocket weight with small launch assist linear turbine/rocket first stage that would weight for example just 1/5X of conventional first stage then you end up with half lighter rocket system that can carry same amount of payload, so its lot of possibilities there, where you can add re usability features like reentry thermal protection for second stage, small wings, additional fuel for first stage landing and so on.
I would feel more safer riding in rocket that is not designed on the edge and was build to last 20 year service time (at least structure) and extra strong structure and plenty of backup safety features. all that could be built in system that has high payload ratio by trading payload to safety/re usability.  and this is the largest problem now. It can be seen in any discussion of reusable rocket stages, for example SpaceX also in press speak about how to make their rockets reusable and add more safety, and they have to trade payload for all those features, or make lighter engines, fuel tanks but these are on the limit already and each improvement is giving less and less payload improvement so its dead end, that means there wont never ever, reach payload figures as high as 6-10% of rocket weight, its impossible without launch assist to combat gravity and atmosphere losses 1,5–2,0 km/s to the delta-v.
so true all stage reusable fly back rocket is possible only with launch assist be it maglev, linear rocket turbine, or rail road mountain slop, ring accelerator. etc.. if it can give at least 1km/s to delta V then we will have new space age, with reusable cheap heavy lift rockets.
and there is my analogy to ships and planes were NEw land America was colonized by ships not planes, so if someone will ever try to colonize space (moon, mars) then we need heavy lift reusable rockets with high payload ratio more than >6% it would be nice to have >10-15% it could be possible if launch assist be in extreme mountain top with >5Km high rocket exit altitude and track length ~4-5km for Mach2-3 exit speeds. (this would be game changer in space colonizations)

Actually YES LEO 'industry' is different, VASTLY different. The analogy of Earth transportation with space transportation simply fails because of the numerous and vast differences between even the most simple transportation systems capable of delivering payload to Orbit and the conditions and requirements which have no analog withing Earth transportation systems.

Direct comparisions just don't work.

Spacecraft are NOT ships, planes, trains or trucks and that's something we have to live with.

The current paradigm will continue to hold unless and until it has been "proven" wrong by demonstrating otherwise. So far any studies done on the subject clearly show that reusablity along with more "cargo-and-passenger" freindly operations and a higher flight rates push access costs down significantly.
This assumes however an expanding market which fully utilizes the benifits offered by streamlined operations and reusabel vehicles.

If one takes a highly conservative approach and assumes that little increased market demand will appear and that the current paradigm of operations and vehicle development will not change significantly any time soon the "up-front" costs of development of reusable vehicles and streamlined operations can be seen to never be acceptable to pursue due to excessive funding requirements.

To re-phrase what Mlorry wrote; Rocket engine and spacecraft people tend to express their designs in seconds/minutes and at best hours. Jet and Aircraft people express their designs in minimums of Hours but most often years and decades. Spacecraft have to reach Aircraft levels of UTILITY even if they don't actually have "days" between maintenance and operations workloads.

Lastly let me say this about payload to orbit; while there may not be a great demand for "small" payloads to orbit of a couple of thousand pounds it is a very simple fact that once you PROVE you can deliver a few thousand pounds cheaply and reliably it suddenly becomes MUCH easier to convince people to invest in your developing and operating the capablity of orbit 10s of thousands of pounds.

Randy

lets calculate LOX/kerosene rocket engine theoretically possible max rocket empty weight(including payload)
lets take Tsiolkovsky rocket equation

if Ve = 3300m/s for kerosene/lox RD-170 engine
delta V for leo including gravity loss, atmosphere loss is about 9.2-9.8 km/s, lets take 9.756 km/s  as final delta V for LEO
so if to get to orbit we will need 94.8% fuel for SSTO rocket so 5.2% will be empty weight. if used 2 stages then number could change, also with better engines number could also change but I doubt it will reach higher than 6% for rocket empty weight + cargo.
so if we use launch assist that will deliver 2139 m/s to total delta V (9.756 km/s in my example for SSTO) then empty weight of launch assisted SSTO with same lox/kerosene engine would be 10%  that's 2x more than max possible for ssto without any launch assist.
so if launch assist decrease delta V at SSTO rocket start up by 21% (2139m/s) then payload will increase 2x, so gains here in this place are high.
real example would be that launch assist will need to push rocket out of atmosphere 31km altitude and horizontal speed 300-400m/s, vertical speed could be smaller, then SSTO rocket will need to deliver its 7617m/s delta V for 10% empty weight calculated example. Jet powered first stage couldn't deliver so high performance, as mountain top linear turbine rocket stage.
and also max available of the shelf jet engine thrust size is 14x lower than rocket engine so can't scale !!   developing new 14x larger thrust Jet engine would be uneconomical I guess.
« Last Edit: 09/08/2011 01:02 pm by Epis »

Offline john smith 19

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Re: Jet Powered First Stage
« Reply #57 on: 09/12/2011 01:17 pm »
Ahhh, ok.. Folks have to be a bit more "careful" when quoting stuff like this :)

See the B1B CAN "carry" that much but it has to be carried over (and through) three "bomb-bays" over the length of the aircraft. (Two aft, one forward with a fuel tank space in the middle)

And "technically" there is a serious issue with the forward end of the forward bay as the crew-boarding ladder actually extends to the ground at an angle that cuts off some access towards the forward bulkhead if your hanging something on the belly :)

Then there is the "issue" with going supersonic with "dangly-bits" hanging in the airstream... (We would also have to consider how to get the Air Force to actually give up the air-frames too which won't be easy :) )

"Cost" is of course one of the biggest issues with just about ANY Launch Assist scheme, especially a supersonic one. The problem is there aren't any "good" civilian supersonic designs that can be used and the majority of the military ones are unavailable. (Or too small)

Which ends up coming back to either a more focused "point-design" type of "minimum" aircraft, or custom (which is what I'd considered the White-Knight aircraft) small production platform if you want "higher-performance" assist.

I agree that HTOL has a lot more "benign" abort options than VTOL but it tends to pretty much "even-out" if you design for engine-out situations. HTOL REALLY shines for lift-off mass IMHO since you don't HAVE to have a high thrust-to-weight if you have wings, but that harkens right back to a "carrier" aircraft versus plain-old launch assist concepts.

It's been a while but I seem to recall the B1b is sub-sonic. Something about it was cheaper to go with fixed inlets and the idea of a low flying supersonic bomber was (IIRC Henry Kissiinger said it) a "turkey".

If the Soviet Union was closing in on shooting down an SR71 with SAM's anything lower and slower would be *virtually* a sitting duck.

Once you're into nap of the earth flying the airframe takes serious buffeting even at (high) sub sonic speed (and supersonic at low altitude you'd get sonic boom reflection off the ground, which should make the ride quite interesting (in ways I'm not qualified to define).

IIRC the most recent obsolete M1+ plane to be scrapped was the European Tornado (I know even less about the Russian situation, which might be better in this regard)*. When I've seen this idea before it's usually been looking at M1+ fighter bombers of the 50s and 60s, EG the F106. The F111 looked quite nice but I'm not sure if it's got a single bomb bay. I think hte "Thunderchief" was allso a candidate for this sort of thing.

The simplest, cheapest launch assist stage is the one you rent from a cargo company *if* you can live with just the benefits of civilian altitude and speed (cM0.8-0.9 and 40Kft) it would give you. Better than a standing start and with an ambient pressure less than 1/4 sea level you should be able to slap quite a big nozzle on it.

But is there a *market* for such a vehicle?

*Late addition. I found that the Russians pitched a small TSTO to Germany c1993 (Burlak?) a liquid fueled TSTO with roughly an 1100Kg payload to LEO dropped out of a "civilian" version of the Tu160 "Blackjack" M2 bomber, which appear to still be in (very) low rate production. Somehow I thought with a lower fuel load you could pack more than a 28000Kg package in the bomb bay.
« Last Edit: 09/13/2011 03:45 pm by john smith 19 »
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #58 on: 09/15/2011 05:00 pm »
It's been a while but I seem to recall the B1b is sub-sonic. Something about it was cheaper to go with fixed inlets and the idea of a low flying supersonic bomber was (IIRC Henry Kissiinger said it) a "turkey".
It's hard on the air-frame yes but the prototype B1A was built for supersonic nap-of-the-Earth flying and did the job well. As long as you don't get to "wild" with the speed (stay around Mach-1) the "yank-and-bank" isn't that severe.

Yes the B1B was "subsonic" with the possiblity of above Mach-1 dash speeds. The B1A with the variable inlets was capabl of dashing to around Mach-2 and sustained flight at Mach-1 at low altitude.

Ol-Henry you might keep in mind never "liked" the fact that the United States had the capability to fight a war with Russia without using ICBMs because it made HIS job harder. Which is why he tended to go out of his way to make the Militaries job harder I suppose :)

Quote
If the Soviet Union was closing in on shooting down an SR71 with SAM's anything lower and slower would be *virtually* a sitting duck.
They couldn't actually come close either. The SR was flying in a "golden" spot with JUST the right airspeed and altitude to make missile interception almost impossible. The Russians even tried several "zoom" manuevers with specially equiped Mig-31s and shorter range (faster) air-to-air missiles. The problem was the shorter range missiles needed more aerodynamic pressure than was available at the specific altitude and they couldn't actually "manuever" to close with the SR in the limited window they had.

And of course the idea of a supersonic penetration (low-and-fast) bomber scared the heck out of them as they were built around centralized air-combat control and such tactics would require high-resolution radar on every combat aircraft and lots of individual pilot intercept work and training. Not something they WANTED to invest in.

Quote
Once you're into nap of the earth flying the airframe takes serious buffeting even at (high) sub sonic speed (and supersonic at low altitude you'd get sonic boom reflection off the ground, which should make the ride quite interesting (in ways I'm not qualified to define).
While flying NOE IS stressful on the airframe both the B-52 and the B-58 managed to transition from high altitude penatration to low-altitude. Of course both suffered from stress cracking and other maintenance and operations issues from doing so but the B-52 was more useful for "conventional" purposes and so it was "upgraded" and repaired where the B-58 which had a limited if anything role for "non-nuclear" warfare was simply retired.

Now if the airframe is actually DESIGNED for such "abuse" the operations and maintenance situation is not bad at all. It was just that at the end of World War II the doctrine called for flying as high as possible to aviod enemy interceptor aircraft. Flying FAST and high meant that the only way an interceptor could come after you was a long, slow tail chase. Then Anti-Aircraft missiles came about and the only thing flying HIGH and fast got you was spotted sooner. Flying REALLY high and REALLY fast still works but it's not practical for a bomber aircraft unfortunatly.

Quote
IIRC the most recent obsolete M1+ plane to be scrapped was the European Tornado (I know even less about the Russian situation, which might be better in this regard)*. When I've seen this idea before it's usually been looking at M1+ fighter bombers of the 50s and 60s, EG the F106. The F111 looked quite nice but I'm not sure if it's got a single bomb bay. I think hte "Thunderchief" was allso a candidate for this sort of thing.
Actually there is a company that is going to use F-104 "Starfighter" aircraft as launch vehicles for micro-sats and such.

The F-111 has issues with where it's landing gear is for such a task. It has two bomb bays one forward of the gear and one aft and the gear is close-spaced and there is very little room for a center-line carry which is usually the best mass carry option.

The F-105 "Thunderchief" is truely a massive fighter aircraft and is both tall and has a clear space along it's center fuselage. Unfortunatly the "bomb-bay" is a rotary system that doesn't work well with external carry. While this could probably be worked around I don't know of any "civil" aircraft and all the military ones were retired to the bone-yard and I think other than those at museums the rest were broken up to comply with arms control agreements. (The F-105 internal bomb bay was specifically designed to carry nuclear weapons so it was considered a "nuclear" platform IIRC)

Quote
The simplest, cheapest launch assist stage is the one you rent from a cargo company *if* you can live with just the benefits of civilian altitude and speed (cM0.8-0.9 and 40Kft) it would give you. Better than a standing start and with an ambient pressure less than 1/4 sea level you should be able to slap quite a big nozzle on it.

But is there a *market* for such a vehicle?

*Late addition. I found that the Russians pitched a small TSTO to Germany c1993 (Burlak?) a liquid fueled TSTO with roughly an 1100Kg payload to LEO dropped out of a "civilian" version of the Tu160 "Blackjack" M2 bomber, which appear to still be in (very) low rate production. Somehow I thought with a lower fuel load you could pack more than a 28000Kg package in the bomb bay.

People often think that just "off-loading" fuel would be a way to increase payload but it doesn't always work that way for aircraft as they need to have "hard-points" linking the carried item(s) to the main structural members of the airframe. The fuel tanks are usually NOT attached to hard points so offloading fuel doesn't increase what they CAN carry attached to the hard-points.

The Burlak:
http://www.astronautix.com/lvs/burlak.htm
wasn't proceeded with as the payload wasn't seen as "useful" enough :)

Technically (per AirLaunch llc, T-Space, etc) a 747-200 could carry a "useful" launch vehicle though "my" personal opinion is to forgo the "simple" pressure-fed 3STO for a higher performance TSTO or aSSTO vehicle :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #59 on: 09/15/2011 06:58 pm »
first your misconception in vertical launch assist rocket approach is that rocket stages will be unusable,...

Where pray-tell did you come up with THIS nonsense? I NEVER stated such an opinion I mearly pointed out that the CURRENT situation and launch market favors Expendable launch vehicles over trying to introduce a "reusable" launch vehicle.

You keep asserting your "assumptions" as facts while ignoring critical back-ground issues such as limited orbital azmiths and infrastructure needs.  As long as you continue to simply "assume" your idea is the best available without some sort of tangible framework of facts and figures to work with it's going to continue to be dismissed out of hand.

Quote
I would feel more safer riding in rocket that is not designed on the edge and was build to last 20 year service time (at least structure) and extra strong structure and plenty of backup safety features. all that could be built in system that has high payload ratio by trading payload to safety/re usability.
Which by the way is exactly opposite of the current factors driving launch vehicle design AND the launch market it supports, so we are back to square one:

HOW does one change the current paradigm to not only allow the building and use of reusable launch vehicles but actually encourage thier development and use? Your continue to assert that your idea makes launch vehicles more "efficient" but you don't acknowledge the costs and limitations that you are ignoring to supposedly arrive at this assumption.

Worse I suppose is you STILL don't actually understand the PROBLEM;

Quote
... and this is the largest problem now. It can be seen in any discussion of reusable rocket stages, for example SpaceX also in press speak about how to make their rockets reusable and add more safety, and they have to trade payload for all those features, or make lighter engines, fuel tanks but these are on the limit already and each improvement is giving less and less payload improvement so its dead end, that means there wont never ever, reach payload figures as high as 6-10% of rocket weight, its impossible without launch assist to combat gravity and atmosphere losses 1,5–2,0 km/s to the delta-v.
so true all stage reusable fly back rocket is possible only with launch assist be it maglev, linear rocket turbine, or rail road mountain slop, ring accelerator. etc.. if it can give at least 1km/s to delta V then we will have new space age, with reusable cheap heavy lift rockets.

You continuely FAIL to note that IF "cheap" Launch is developed then the COST of buidling and maintaining the INFRASTRUCTURE that allows it is NOW a large factor in launch costs. So IF "Launch-Assist" is required to make rocket flight cheap then the LAUNCH ASSIST has to be low-cost both to build and to operate which none of the "methods" you list is such!

Worse yet is that you keep trying to apply it to HEAVY payloads which are the LEAST often flown and therefore the MOST expensive to begin with!

Probably THE worst issue with your concepts it you continually try to apply Earth-based transportation analogy to the radically different issues of space transportation;
Quote
and there is my analogy to ships and planes were NEw land America was colonized by ships not planes, so if someone will ever try to colonize space (moon, mars) then we need heavy lift reusable rockets with high payload ratio

And what you keep coming back to is:
Quote
more than >6% it would be nice to have >10-15% it could be possible if launch assist be in extreme mountain top with >5Km high rocket exit altitude and track length ~4-5km for Mach2-3 exit speeds. (this would be game changer in space colonizations)
Which is totally false given YOUR assumption that some how hand-waving away the extreme cost of building and operating such a system will ensure that it is never a 'cost-effective' launch assist method will NOT make it a "game-changer" for space access.

The INCENTIVE, the MARKET for the huge outlay of money and resources as something such as you suggest HAS TO BE IN PLACE FIRST! You can't 'create' the market or incentive by building a huge, costly, limited use system and expecting costs to drop, historically in any transportation system the opposite has happened. And space access is different in that it has neither a "major" economic draw such as easily exploited or tapped resources, nor the government or civil interest to expend large amounts of money to develop or search for such a "draw" factor.

"Space Colonization" has to not only boot-strap itself out of a deep gravity well energy-wise, but it also has to both economic and social development as well and NOTHING in space has been found to push any of these factors forward from their current position.

Actually YES LEO 'industry' is different, VASTLY different. The analogy of Earth transportation with space transportation simply fails because of the numerous and vast differences between even the most simple transportation systems capable of delivering payload to Orbit and the conditions and requirements which have no analog within Earth transportation systems.

Direct comparisons just don't work.

Spacecraft are NOT ships, planes, trains or trucks and that's something we have to live with.

The current paradigm will continue to hold unless and until it has been "proven" wrong by demonstrating otherwise. So far any studies done on the subject clearly show that reusability along with more "cargo-and-passenger" friendly operations and a higher flight rates push access costs down significantly.
This assumes however an expanding market which fully utilizes the benefits offered by streamlined operations and reusable vehicles.

If one takes a highly conservative approach and assumes that little increased market demand will appear and that the current paradigm of operations and vehicle development will not change significantly any time soon the "up-front" costs of development of reusable vehicles and streamlined operations can be seen to never be acceptable to pursue due to excessive funding requirements.

To re-phrase what Mlorry wrote; Rocket engine and spacecraft people tend to express their designs in seconds/minutes and at best hours. Jet and Aircraft people express their designs in minimums of Hours but most often years and decades. Spacecraft have to reach Aircraft levels of UTILITY even if they don't actually have "days" between maintenance and operations workloads.

Lastly let me say this about payload to orbit; while there may not be a great demand for "small" payloads to orbit of a couple of thousand pounds it is a very simple fact that once you PROVE you can deliver a few thousand pounds cheaply and reliably it suddenly becomes MUCH easier to convince people to invest in your developing and operating the capability of orbit 10s of thousands of pounds.

You quoted this entire passage and then go into trying to “justify” launch assist as helping lower the cost of orbital launch. What you FAIL to understand is that no one here has made any mention of launch-assist for surface launched rockets NOT having a positive effect on payload, nor has anyone tried to deny that it would help with the performance of payload-to-orbit, and other factors of rocket design.

While I appreciate you reiterating my main points over again for me, I would have been more apprciative if YOU had simply read them again and tried to understand what I'm say.

It's fairly obvioius you don't or don't want to at any rate as you then work a long example of a "RP-1/LOX" SSTO and try to "prove" that launch assist provides a way to increase both the vehicle empty mass allowence AND payload to orbit. Congratulations, you've discovered what is freely available at hundereds of websites on the internet. Unfortunatly you then try to somehow "justify" spending hundreds of millions of dollars to build and operate a "mountain-top, linear turbine rocket" launch assist device to spit out a "generic-SSTO" design at Mach-6.5 and around 100,000ft altitude. And you "suppose" this is would be cheaper than desiging and building an "assisted" SSTO launched by more conventional (and cheaper) means? Even a Two-Stage-To-Orbit Vehicle would be less expensive, and more useful and your refusal to even do some minimum calculations on the cost and complexity of your "choosen" concept shows that you are less interested in actually investigating possible launch assist concepts than in getting "recognized" for raising a not very well thought-out or researched "favorite" idea.

Fine by me. Your loss.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Jim

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Re: Jet Powered First Stage
« Reply #60 on: 09/15/2011 07:01 pm »
thank you Randy. 

+100
« Last Edit: 09/15/2011 07:01 pm by Jim »

Offline Epis

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Re: Jet Powered First Stage
« Reply #61 on: 09/16/2011 10:44 am »
Fine by me. Your loss.
Randy

that was large post.
from what I understand that large structural investments for launch assist is only reason why it don't fit in ?
I see it either way, I could draw parallels to nuclear power plant building which takes 10+ years to build and huge biljon $ investments, but after built it generates money for more than 60-80 years, even longer if properly maintained. so its extremely long term thinking, and fuel costs are tiny 3% of operation costs.
so in short term you win, in long term you loss, I win.  so at the end of the day I win :)

I have made lot of different calculations in past (made my own C# calculation software) about launch assist using existing basic rocket model parameters from ariane 5, falcon 1;9 to get some +- basic math numbers, and draw some conclusions.
even if this mountain side rail track launch assist will need 30-40 years to pay back for itself and will take 10+ years to built, it will be much better, cost less compared to space shuttle which was economically grand failure and ended up xx times more expensive as predicted in development, and was uneconomical compared to old Russian Soyuz old tech USSR rocket, that still is in business.
at least compared to shuttle, rocket that will be launched with launch assist will consume 2/3 less fuel energy, will be smaller/lighter, significantly stronger built, higher safety levels and be also reusable. so in every way it could be built better thanks to launch assist and long term thinking, by choosing most energy efficient path to LEO.

I am already tired to explaining same thing many times.
 so no more talking from me!
 if you all get it. that fine, if not, then not.
after all its not my problem, nor I can make some ideological believe changes in any mind. 

forgot to mention about astronomy where they chose to go to high altitude places like Chile Atacama desert 5000+m latitude to place their telescopes, to sea father, and even better than Hubble telescope, and such high altitude places were of course expensive but in long term offered more benefits compared to orbital telescope in space, like fast new equipment installation, testing, so that constant tech improvements can be made, and tested, and they improving tech really fast.
« Last Edit: 09/16/2011 10:56 am by Epis »

Offline Jim

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Re: Jet Powered First Stage
« Reply #62 on: 09/16/2011 12:51 pm »
1.  I see it either way, I could draw parallels to nuclear power plant building which takes 10+ years to build and huge biljon $ investments, but after built it generates money for more than 60-80 years, even longer if properly maintained. so its extremely long term thinking, and fuel costs are tiny 3% of operation costs.
so in short term you win, in long term you loss, I win.  so at the end of the day I win :)

2. even if this mountain side rail track launch assist will need 30-40 years to pay back for itself and will take 10+ years to built,

1.  Not in the US.  Nuclear power is not cheaper

2. "30-40 years" is a flawed assumption.  Can not use Shuttle and R-7 as examples.  That is why you idea does not work.

Offline john smith 19

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Re: Jet Powered First Stage
« Reply #63 on: 09/16/2011 07:58 pm »

that was large post.
from what I understand that large structural investments for launch assist is only reason why it don't fit in ?
No. Some are but some are not. However it's the risk factor of the *known* path (Liquid TSTO ELV) Vs the unknown. A new ELV (or a system any of whose *stages*) is an ELV starts with establishing credibility. So you're customer is taking a *big* risk when they don't have to. Consider what Spacex had to do to establish themselves (and still doing) to establish themselves.

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I see it either way, I could draw parallels to nuclear power plant building which takes 10+ years to build and huge biljon $ investments, but after built it generates money for more than 60-80 years,
even longer if properly maintained. so its extremely long term thinking, and fuel costs are tiny 3% of operation costs.
Which plants did you have in mind?
Obninsk (48 years) or Oyster Creek (startup 1969, inspection says good to 2029, license extended to 2019)or Fessenheim (startup 1977)?
http://en.wikipedia.org/wiki/Obninsk_Nuclear_Power_Plant
http://www.physorg.com/news/2011-03-oldest-nuclear-reactor-disaster.html
http://en.wikipedia.org/wiki/Fessenheim_Nuclear_Power_Plant

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so in short term you win, in long term you loss, I win.  so at the end of the day I win :)
And if you are a high net worth  individual I will wish you good luck with your plan. For those of us whose names do not end Gates, Ellison or Musk we will have to raise the money from someone else. 
It will be your *investors* you will have to convince.

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I have made lot of different calculations in past (made my own C# calculation software) about launch assist using existing basic rocket model parameters from ariane 5, falcon 1;9 to get some +- basic math numbers, and draw some conclusions.
even if this mountain side rail track launch assist will need 30-40 years to pay back for itself and will take 10+ years to built, it will be much better, cost less compared to space shuttle which was economically grand failure and ended up xx times more expensive as predicted in development, and was uneconomical compared to old Russian Soyuz old tech USSR rocket, that still is in business.
Perhaps so. The same sort of calculations that "proved" NASP was feasible. Look up "Facing the heat barrier" 
history.nasa.gov/sp4232-part3.pdf

Turned out the PI had made *several* mistakes in his model. Several *billion* dollars later the US govt realized they'd failed. Dr DuPont has had a "colorful" career since.

You should be *very* cautious about computer models that give unexpectedly good answers. Specifically values of *all* constants and *assumptions* about behavior.

The equations you need to run in this context relate to the "Internal Rate of Return" and "Discounted cash flow" methods of assessing weather the proposed investment is worthwhile. 

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at least compared to shuttle, rocket that will be launched with launch assist will consume 2/3 less fuel energy, will be smaller/lighter, significantly stronger built, higher safety levels and be also reusable. so in every way it could be built better thanks to launch assist and long term thinking, by choosing most energy efficient path to LEO.
You might like to Google the "groups" section under "sci.space.*"

If you think you're ideas are new you have a *lot* to learn.

If you think the *propellant* costs are the problem you might like to know that in the US LOX is roughly $0.15/lb and LH2 is c$6/lb (NASA prices). The *most* expensive liquid fuels are the hydrazines at about $60/lb My last price for SRB propellant was about $6/lb but that was in the early 80s.

Using the known tank sizes and propellant masses work out their filling costs and know that a Shuttle launch costs roughly $400m in *total*.

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I am already tired to explaining same thing many times.
 so no more talking from me!
 if you all get it. that fine, if not, then not.
after all its not my problem, nor I can make some ideological believe changes in any mind. 
We got it. We got it when Bono explained Hyperion and the West German govt proposed Sanger (the *original* Sanger concept, not the 1980s design). You have much to discover.

BTW While personal and impersonal pronouns may seem redundant in English they greatly aid understanding. You might like to make more frequent use of them.

You might also like to look at the history and funding of *other* large engineering projects such as major hydroelectric dams or the UK/French Channel tunnel. Your investors will also be aware of them and what good deals they turned out to be for the investors. :(

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forgot to mention about astronomy where they chose to go to high altitude places like Chile Atacama desert 5000+m latitude to place their telescopes, to sea father, and even better than Hubble telescope, and such high altitude places were of course expensive but in long term offered more benefits compared to orbital telescope in space, like fast new equipment installation, testing, so that constant tech improvements can be made, and tested, and they improving tech really fast.
Which *can* be read as a reason to abandon space based science, or even human spaceflight in general.

I'll presume you mean that more frequent access to an environment, even one as hostile as the mountains of Chile, speeds up the development cycle and overcomes the advantages of an earlier generation instrument in a less frequently accessible (but better visibility) environment.

True. So what?

There has to exist a *need* to go there in the first place and a *want* to lower the costs of doing so. To use some numbers I just made up *if* it cost a $100Bn for a new *compatible* launch system to save $100m/launch the first *real* saving I'd make would be on the 1001st launch.  That's not the Shuttle programme (135 launches) that's the *whole* of the USSR/Russia launch programme over the last 1/2 century.

Now do you *you* "get it"?
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline mlorrey

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Re: Jet Powered First Stage
« Reply #64 on: 09/17/2011 01:36 am »
Ahhh, ok.. Folks have to be a bit more "careful" when quoting stuff like this :)

See the B1B CAN "carry" that much but it has to be carried over (and through) three "bomb-bays" over the length of the aircraft. (Two aft, one forward with a fuel tank space in the middle)

And "technically" there is a serious issue with the forward end of the forward bay as the crew-boarding ladder actually extends to the ground at an angle that cuts off some access towards the forward bulkhead if your hanging something on the belly :)

Then there is the "issue" with going supersonic with "dangly-bits" hanging in the airstream... (We would also have to consider how to get the Air Force to actually give up the air-frames too which won't be easy :) )

"Cost" is of course one of the biggest issues with just about ANY Launch Assist scheme, especially a supersonic one. The problem is there aren't any "good" civilian supersonic designs that can be used and the majority of the military ones are unavailable. (Or too small)

Which ends up coming back to either a more focused "point-design" type of "minimum" aircraft, or custom (which is what I'd considered the White-Knight aircraft) small production platform if you want "higher-performance" assist.

I agree that HTOL has a lot more "benign" abort options than VTOL but it tends to pretty much "even-out" if you design for engine-out situations. HTOL REALLY shines for lift-off mass IMHO since you don't HAVE to have a high thrust-to-weight if you have wings, but that harkens right back to a "carrier" aircraft versus plain-old launch assist concepts.

It's been a while but I seem to recall the B1b is sub-sonic. Something about it was cheaper to go with fixed inlets and the idea of a low flying supersonic bomber was (IIRC Henry Kissiinger said it) a "turkey".

If the Soviet Union was closing in on shooting down an SR71 with SAM's anything lower and slower would be *virtually* a sitting duck.

Once you're into nap of the earth flying the airframe takes serious buffeting even at (high) sub sonic speed (and supersonic at low altitude you'd get sonic boom reflection off the ground, which should make the ride quite interesting (in ways I'm not qualified to define).

IIRC the most recent obsolete M1+ plane to be scrapped was the European Tornado (I know even less about the Russian situation, which might be better in this regard)*. When I've seen this idea before it's usually been looking at M1+ fighter bombers of the 50s and 60s, EG the F106. The F111 looked quite nice but I'm not sure if it's got a single bomb bay. I think hte "Thunderchief" was allso a candidate for this sort of thing.

The simplest, cheapest launch assist stage is the one you rent from a cargo company *if* you can live with just the benefits of civilian altitude and speed (cM0.8-0.9 and 40Kft) it would give you. Better than a standing start and with an ambient pressure less than 1/4 sea level you should be able to slap quite a big nozzle on it.

But is there a *market* for such a vehicle?

*Late addition. I found that the Russians pitched a small TSTO to Germany c1993 (Burlak?) a liquid fueled TSTO with roughly an 1100Kg payload to LEO dropped out of a "civilian" version of the Tu160 "Blackjack" M2 bomber, which appear to still be in (very) low rate production. Somehow I thought with a lower fuel load you could pack more than a 28000Kg package in the bomb bay.

The F-106 was NOT a fighter bomber, it was an interceptor, designed purely to fly beyond mach 2 to intercept russian bomber formations and launch a nuclear tipped genie missile into the middle of the formations. Nor was it 'cancelled', the F-106 flew from 1958 until the early 1980's in the USAF active duty inventory. The 106 held the speed record for fighter planes until McDonnell Douglas rigged up an MIPCC system in an F-4 intakes to beat that record with a non-spec vehicle. The 106 was never designed for nape of the earth flight, it was built to get to altitude as fast as possible and intercept high altitude bombers. It's delta wing planform is a terrible design for nape of the earth because turning a delta wing, esp without a canard, loses tons of energy and is impossible to do in a tight radius without thrust vectoring.

The F-111 does have a single bomb bay which can carry two paveway laser guided bombs, or just one if its going to guide its own bombs cause the guidance package is installed in one of the bomb bay doors and takes up space in the bomb bay. The 111 is a hog with poor performance, terrible acceleration, and is overweight. (I've worked on this plane so I know it intimately).

The B-1 was supersonic, designed for mach 1.2 flight. The B-1B was a modified to be subsonic, with fixed inlets rather than variable ramp inlets, and more work done on improving its stealth characteristics, and yes, its quite rugged and I've seen pilots fly it into aerobatics one normally sees in fighter planes. Supersonic speed is a detriment when you are trying to be stealthy. In the 70's the US decided speed and altitude were less useful characteristics and stealth was far more important (and it has been proven right in this respect). Flying supersonic speeds creates sonic booms, which is stupid to be making when you are trying to be invisible. Kissinger was ignorant of military tactics and his opinion on this is meaningless.
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Offline john smith 19

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Re: Jet Powered First Stage
« Reply #65 on: 09/18/2011 05:28 pm »
The F-106 was NOT a fighter bomber, it was an interceptor, designed purely to fly beyond mach 2 to intercept russian bomber formations and launch a nuclear tipped genie missile into the middle of the formations.
It's been a *long* time since I read up on it. I recalled it had an internal bay for nuclear weapons (later used for anti radar missions IIRC) but forgot they were not free fall bombs.

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Nor was it 'cancelled', the F-106 flew from 1958 until the early 1980's in the USAF active duty inventory.
I don't think I said it was. RASCAl was cancelled.
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The 106 held the speed record for fighter planes until McDonnell Douglas rigged up an MIPCC system in an F-4 intakes to beat that record with a non-spec vehicle.
]
Was that written up anywhere? I think it *might* be the basis of the claims by the DARPA RASCAL team that the technology had *already* been tested.
Quote
The 106 was never designed for nape of the earth flight, it was built to get to altitude as fast as possible and intercept high altitude bombers. It's delta wing planform is a terrible design for nape of the earth because turning a delta wing, esp without a canard, loses tons of energy and is impossible to do in a tight radius without thrust vectoring.
Most of my comments were directed to the B1 Lancer, b (subsonic) version.
Quote
The F-111 does have a single bomb bay which can carry two paveway laser guided bombs, or just one if its going to guide its own bombs cause the guidance package is installed in one of the bomb bay doors and takes up space in the bomb bay. The 111 is a hog with poor performance, terrible acceleration, and is overweight. (I've worked on this plane so I know it intimately).
However the *single* bomb bay makes it quite a good candidate for a "Jet powered 1st stage" Ditching most of the military avionics should improve the performance and with an automated launch sequence it would only need a pilot to fly the correct profile before hitting the "launch" button. The Lockheed aircraft OSC used for Pegasus launches is not known for its fuel economy but given its low flight rate and relatively short flying times that's not an issue.
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The B-1 was supersonic, designed for mach 1.2 flight. The B-1B was a modified to be subsonic, with fixed inlets rather than variable ramp inlets,
I emphasize the distinction between the original "a" version and the "b" to point out that if you did get a b (which IIRC most of them were) you'd need to do *lots* of specialized work to get it above M1

Quote
Supersonic speed is a detriment when you are trying to be stealthy. In the 70's the US decided speed and altitude were less useful characteristics and stealth was far more important (and it has been proven right in this respect).
Agreed. The low RCS of the SR71 was a *critical* component of its survival.
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Flying supersonic speeds creates sonic booms, which is stupid to be making when you are trying to be invisible.
I'd suggest that depends on what height you're flying at. The SR71 being the obvious case. However I'll bet it's IR signature was quite something.

TBH If you are going for an aircraft launch assist I'm inclined to sacrifice speed and altitude for shear weight carrying capacity and go with an Antonov "Spirit" or a C17 and rely on their ability to carry something with a *really* big nozzle

Would you care to nominate any other aircraft capable of M1+ carriage of an LV?
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline intlibber

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Re: Jet Powered First Stage
« Reply #66 on: 09/20/2011 12:10 am »
Yeah, the Hustler and the Concorde, and whatever that russian SST is, Tu-144? Tall landing gear, lots of room to drop an orbital stage from. Oh, and lest we trigger a response from the curmudgeons, don't forget the B-70, allegedly used as a mother ship for the "Blackstar" secret shuttle...

As for MIPCC: this was commonly used in the early jet era to boost engine performance before afterburners became powerful. F-100's used the technology quite a bit.
http://www.ssdl.gatech.edu/papers/mastersProjects/YoungD-8900.pdf

This study shows that MIPCC can make a turbofan engine fly at mach 4, thinking its going mach 1.6.... and at 90,000 feet, think its at 25,000 ft.

4. Pratt and Whitney Products: F-100, URL: http://www.prattwhitney.com/prod_mil_f100.asp, Last visited 5/2/04.
5. Bechtel, Ryan, “Turbine Based Engine Analysis Tool”. URL:
http://www.ssdl.gatech.edu/~ssdl/T-BEAT/T-BEAT.html , Last visited 4/15/04.
6. Carter, Preston, “Mass Injection and Precompressor Cooling Engines Analyses,”
AIAA-2002-4127, 38th AIAA Joint Propulsion Conference and Exhibit,
Indianapolis, Indiana, July 7-10 2002.
« Last Edit: 09/20/2011 12:21 am by intlibber »

Offline john smith 19

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Re: Jet Powered First Stage
« Reply #67 on: 09/20/2011 07:02 am »
Yeah, the Hustler and the Concorde, and whatever that russian SST is, Tu-144? Tall landing gear, lots of room to drop an orbital stage from. Oh, and lest we trigger a response from the curmudgeons, don't forget the B-70, allegedly used as a mother ship for the "Blackstar" secret shuttle...
Both the Concorde and Tu-144 *might* have the payload but were *never* designed for captive carry internally or externally (I'll admit a Concorde with drop tanks would have been *interesting*)
The B70 has 1 remaining example. However in principle the blueprints are still around (and like those for the SSME they really *are* Blue) and could be recreated (engines could be a problem) but the cost would be huge.

I'd forgotten the B58 and the fact it carried that huge fuel/nuke pod makes it a very good candidate. High landing gear, and a quite extensive aerodynamic database. But how many of them still even exist? I'd guess you might get one in flying condition. Under rated. For this application flying hours would not be too big a problem and junking that 50's era avionics (IIRC the B58 has a *heavy* nav/bombing system that is redundant, along with at least 1 crew position you could eliminate for an even bigger weight saving, unless you remain keen on attacking Moscow by air :)).

Quote
As for MIPCC: this was commonly used in the early jet era to boost engine performance before afterburners became powerful. F-100's used the technology quite a bit.
http://www.ssdl.gatech.edu/papers/mastersProjects/YoungD-8900.pdf

This study shows that MIPCC can make a turbofan engine fly at mach 4, thinking its going mach 1.6.... and at 90,000 feet, think its at 25,000 ft.

4. Pratt and Whitney Products: F-100, URL: http://www.prattwhitney.com/prod_mil_f100.asp, Last visited 5/2/04.
5. Bechtel, Ryan, “Turbine Based Engine Analysis Tool”. URL:
http://www.ssdl.gatech.edu/~ssdl/T-BEAT/T-BEAT.html , Last visited 4/15/04.
6. Carter, Preston, “Mass Injection and Precompressor Cooling Engines Analyses,”
AIAA-2002-4127, 38th AIAA Joint Propulsion Conference and Exhibit,
Indianapolis, Indiana, July 7-10 2002.
You need to be careful with the use of the term MIPCC. Water injection was *fairly* common and IIRC some airliners used it as well (including the 707s) and seems to be still popular for ground based mobile electricity generating turbines. LOX injection has *never* been common anywhere. Note WI would have been *designed* into the package, not retro fitted later.

I would suggest anyone who describes adding  a combined water and LOX injection system as just a "plug in" should be viewed with extreme skepticism.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #68 on: 09/20/2011 04:38 pm »
Yeah, the Hustler and the Concorde, and whatever that russian SST is, Tu-144? Tall landing gear, lots of room to drop an orbital stage from. Oh, and lest we trigger a response from the curmudgeons, don't forget the B-70, allegedly used as a mother ship for the "Blackstar" secret shuttle...
Both the Concorde and Tu-144 *might* have the payload but were *never* designed for captive carry internally or externally (I'll admit a Concorde with drop tanks would have been *interesting*)
The B70 has 1 remaining example. However in principle the blueprints are still around (and like those for the SSME they really *are* Blue) and could be recreated (engines could be a problem) but the cost would be huge.
VERY huge given there isn't any of the tooling or even experiance for working the materials. The problem with both the Concorde and Tu-144 is hanging "dangly-bits" under the fuselage would totally change the transonic and supersonic airflow which would seriously adversely effect the engine operations.

However as noted there is enough plans and data to forseably build "new" versions using more modern techniques and equipment.

And just for interlibber's information the supposed "Blackstar" mother-ship was noted as being "XB-70 like" rather than a supposed version of the bomber itself.

Quote
I'd forgotten the B58 and the fact it carried that huge fuel/nuke pod makes it a very good candidate. High landing gear, and a quite extensive aerodynamic database. But how many of them still even exist? I'd guess you might get one in flying condition. Under rated. For this application flying hours would not be too big a problem and junking that 50's era avionics (IIRC the B58 has a *heavy* nav/bombing system that is redundant, along with at least 1 crew position you could eliminate for an even bigger weight saving, unless you remain keen on attacking Moscow by air :)).
You may continue to "forget" the B-58 unfortunatly. There are NO "flyable" example left. Except for a few examples in museums the rest were scrapped or worse. This was partially because they were not in very good condition when the AF finally "retired" them. If you recall our discussion of low and fast flight, the majority of the B-58s did NOT fare all that well when doctrined changed from high and fast to low and fast. The airframe just wasn't designed to take the beating. Given up-grades as was the B-52 it's possible they would have probably lasted longer but there was no incentive to do so.

Though again, there are plans and such so as to be able to replicate the airframe in more modern materials.

Quote
Quote
As for MIPCC: this was commonly used in the early jet era to boost engine performance before afterburners became powerful. F-100's used the technology quite a bit.
http://www.ssdl.gatech.edu/papers/mastersProjects/YoungD-8900.pdf

This study shows that MIPCC can make a turbofan engine fly at mach 4, thinking its going mach 1.6.... and at 90,000 feet, think its at 25,000 ft.

4. Pratt and Whitney Products: F-100, URL: http://www.prattwhitney.com/prod_mil_f100.asp, Last visited 5/2/04.
5. Bechtel, Ryan, “Turbine Based Engine Analysis Tool”. URL:
http://www.ssdl.gatech.edu/~ssdl/T-BEAT/T-BEAT.html , Last visited 4/15/04.
6. Carter, Preston, “Mass Injection and Precompressor Cooling Engines Analyses,”
AIAA-2002-4127, 38th AIAA Joint Propulsion Conference and Exhibit,
Indianapolis, Indiana, July 7-10 2002.
You need to be careful with the use of the term MIPCC. Water injection was *fairly* common and IIRC some airliners used it as well (including the 707s) and seems to be still popular for ground based mobile electricity generating turbines. LOX injection has *never* been common anywhere. Note WI would have been *designed* into the package, not retro fitted later.

I would suggest anyone who describes adding  a combined water and LOX injection system as just a "plug in" should be viewed with extreme skepticism.
The use of "mass-injection" for early jets WAS built in and it should be noted that it was NOT usually "MIPCC" type but was built to inject into the exhaust, not the incoming air-stream. The cited examples in the GT paper and most other RASCAL papers where studies and tests for proposed Mach-3 "dash" interceptors capable of short duration, very high speed, very high altitude missions with very limited endurance. Which is why "pre-compressor" cooling and injection was dropped as an operational consideration since the system doesn't lend itself to prolonged operations. (Again this example system would have been "designed-in" to the aircraft rather than an attached system. But this was also different consideration than for the RASCAL work)

However, the majority of the work done on MIPCC was specifically towards a "plug-in" or "bolt-on" system with all injectents now specifically injected into the incoming airstream alone. A system also being capable of being fitted to other engines rather than exclusivly to the F100. While LOX injection technology is and has not been "common" overall performance boosting by injection HAS as noted in both early jet aircraft and for needed performance boost in some operational more modern aircraft.
(I should also point out that ANOTHER reason for injection of water into a tubojet exhaust is noise mitigation. This was, along with thrust augmentation, a major reason for water injection in early civil jet airliners)

You'd asked earlier for a "citation" on the F-4 world speed record using mass injection.
(Granted it's Wikipedea but...)
http://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II

"Operation Skyburner: On 22 December 1961, a modified Phantom with water injection set an absolute world record speed of 1,606.342 mph (2,585.086 km/h)."

A variant of the MIG-31 also used injection (methanol IIRC) for thrust boost at high speed and altitude.

The MIPCC rig itself WAS extensivly tested in a purpose built test facility prior to RASCAL being canceled though to what simulated "speeds" I don't know.
http://ftp.rta.nato.int/public//PubFullText/RTO/TR/RTO-TR-AVT-007-V3///TR-AVT-007-V3-$$TOC.pdf

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline mlorrey

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Re: Jet Powered First Stage
« Reply #69 on: 09/21/2011 12:45 am »
Yeah, the Hustler and the Concorde, and whatever that russian SST is, Tu-144? Tall landing gear, lots of room to drop an orbital stage from. Oh, and lest we trigger a response from the curmudgeons, don't forget the B-70, allegedly used as a mother ship for the "Blackstar" secret shuttle...
Both the Concorde and Tu-144 *might* have the payload but were *never* designed for captive carry internally or externally (I'll admit a Concorde with drop tanks would have been *interesting*)
The B70 has 1 remaining example. However in principle the blueprints are still around (and like those for the SSME they really *are* Blue) and could be recreated (engines could be a problem) but the cost would be huge.
VERY huge given there isn't any of the tooling or even experiance for working the materials. The problem with both the Concorde and Tu-144 is hanging "dangly-bits" under the fuselage would totally change the transonic and supersonic airflow which would seriously adversely effect the engine operations.

However as noted there is enough plans and data to forseably build "new" versions using more modern techniques and equipment.

And just for interlibber's information the supposed "Blackstar" mother-ship was noted as being "XB-70 like" rather than a supposed version of the bomber itself.

Allegedly, the Blackstar mothership was built from XB-70 parts, it is claimed there was a warehouse with three planes worth of parts in it that they used. The bomb bays are between the intakes on the Val, which you can confirm looking at any old diagrams. Thats allegedly where the orbiter was dropped from.
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Offline mlorrey

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Re: Jet Powered First Stage
« Reply #70 on: 09/21/2011 01:03 am »
Some others from the USSR: The Sukhoi T-4, their answer to the XB-70, as well as the Bounder. I also notice the Tu-95 Bear bomber, tho subsonic has a very high landing carriage, plenty of room under the fuselage centerline for a big LV.
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Offline john smith 19

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Re: Jet Powered First Stage
« Reply #71 on: 09/21/2011 12:04 pm »
Some others from the USSR: The Sukhoi T-4, their answer to the XB-70, as well as the Bounder. I also notice the Tu-95 Bear bomber, tho subsonic has a very high landing carriage, plenty of room under the fuselage centerline for a big LV.
Both the T-4 and the M-50 Bounder were big beasts The T-4 is quite lovely but both only exist as *single* prototypes. At least the B58 had lots of copies made. Sadly they all appear to be scrap.

The Tu95 is interesting. IIRC the early ones carried some monster anti shipping cruise missile under the fuselage like the X1 supersonic test plan. More to the point if it's still in service there should be *lots* of them around and a fairly good supply of spare parts.

While I can understand not using a foreign rocket engine for ELV's for fear of having supplies cut off I've never understood the US reluctance to look at foreign aircraft for 1st stage carriers. If the types fairly prolific you should be able to lease from several places or buy a couple and parts should be fairly easy to come by. As OSC showed the usual criteria for purchasing a large transport or passenger airliner don't apply for an air launch carrier.

Personally I still prefer internal carriage from an OTS transport aircraft that requires *no* modifications. The air drop and ignition of an 89000lb Minuteman stage from the back of a C5 in 1974 pretty much ended the argument for me. How to make maximum *effective* use of the space in the cargo plane of your choice is still an open question.
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Offline mlorrey

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Re: Jet Powered First Stage
« Reply #72 on: 09/21/2011 03:47 pm »
The US govt will always prefer domestically manufactured items from a national security as well as to comply with 'made in america' legislation.

That said, I would also point out that supersonic british delta winged bomber.
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Offline Downix

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Re: Jet Powered First Stage
« Reply #73 on: 09/21/2011 04:40 pm »
Yeah, the Hustler and the Concorde, and whatever that russian SST is, Tu-144? Tall landing gear, lots of room to drop an orbital stage from. Oh, and lest we trigger a response from the curmudgeons, don't forget the B-70, allegedly used as a mother ship for the "Blackstar" secret shuttle...
Both the Concorde and Tu-144 *might* have the payload but were *never* designed for captive carry internally or externally (I'll admit a Concorde with drop tanks would have been *interesting*)
The B70 has 1 remaining example. However in principle the blueprints are still around (and like those for the SSME they really *are* Blue) and could be recreated (engines could be a problem) but the cost would be huge.
VERY huge given there isn't any of the tooling or even experiance for working the materials. The problem with both the Concorde and Tu-144 is hanging "dangly-bits" under the fuselage would totally change the transonic and supersonic airflow which would seriously adversely effect the engine operations.

However as noted there is enough plans and data to forseably build "new" versions using more modern techniques and equipment.

And just for interlibber's information the supposed "Blackstar" mother-ship was noted as being "XB-70 like" rather than a supposed version of the bomber itself.

Allegedly, the Blackstar mothership was built from XB-70 parts, it is claimed there was a warehouse with three planes worth of parts in it that they used. The bomb bays are between the intakes on the Val, which you can confirm looking at any old diagrams. Thats allegedly where the orbiter was dropped from.
Claim as much as they want, they only had enough parts for the two planes they did build, and one was destroyed in a mid-air collision.

The beauty of conspiracy theories, they only work if hundreds of thousands, if not millions of people are in on it.  You cannot build an airplane like the B-70 without a substantial factory, and the workers involved.
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Offline Jim Davis

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Re: Jet Powered First Stage
« Reply #74 on: 09/21/2011 05:12 pm »
That said, I would also point out that supersonic british delta winged bomber.

What supersonic British delta winged bomber would that be? TSR2? Scrapped decades ago.

Offline mlorrey

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Re: Jet Powered First Stage
« Reply #75 on: 09/21/2011 10:36 pm »
Yeah, the Hustler and the Concorde, and whatever that russian SST is, Tu-144? Tall landing gear, lots of room to drop an orbital stage from. Oh, and lest we trigger a response from the curmudgeons, don't forget the B-70, allegedly used as a mother ship for the "Blackstar" secret shuttle...
Both the Concorde and Tu-144 *might* have the payload but were *never* designed for captive carry internally or externally (I'll admit a Concorde with drop tanks would have been *interesting*)
The B70 has 1 remaining example. However in principle the blueprints are still around (and like those for the SSME they really *are* Blue) and could be recreated (engines could be a problem) but the cost would be huge.
VERY huge given there isn't any of the tooling or even experiance for working the materials. The problem with both the Concorde and Tu-144 is hanging "dangly-bits" under the fuselage would totally change the transonic and supersonic airflow which would seriously adversely effect the engine operations.

However as noted there is enough plans and data to forseably build "new" versions using more modern techniques and equipment.

And just for interlibber's information the supposed "Blackstar" mother-ship was noted as being "XB-70 like" rather than a supposed version of the bomber itself.

Allegedly, the Blackstar mothership was built from XB-70 parts, it is claimed there was a warehouse with three planes worth of parts in it that they used. The bomb bays are between the intakes on the Val, which you can confirm looking at any old diagrams. Thats allegedly where the orbiter was dropped from.
Claim as much as they want, they only had enough parts for the two planes they did build, and one was destroyed in a mid-air collision.

The beauty of conspiracy theories, they only work if hundreds of thousands, if not millions of people are in on it.  You cannot build an airplane like the B-70 without a substantial factory, and the workers involved.

Not necessarily. I was part of a team that built a T/A-4J in a hangar from three boneyard hulks, and which is still flying, 16 years later.... There were no more than a dozen people involved in this project, which was a lot more than just an assembly job, we had to remanufacture a lot of structural components.
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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #76 on: 09/26/2011 05:10 pm »
Allegedly, the Blackstar mothership was built from XB-70 parts, it is claimed there was a warehouse with three planes worth of parts in it that they used. The bomb bays are between the intakes on the Val, which you can confirm looking at any old diagrams. Thats allegedly where the orbiter was dropped from.
Claim as much as they want, they only had enough parts for the two planes they did build, and one was destroyed in a mid-air collision.

The beauty of conspiracy theories, they only work if hundreds of thousands, if not millions of people are in on it.  You cannot build an airplane like the B-70 without a substantial factory, and the workers involved.

Not necessarily. I was part of a team that built a T/A-4J in a hangar from three boneyard hulks, and which is still flying, 16 years later.... There were no more than a dozen people involved in this project, which was a lot more than just an assembly job, we had to remanufacture a lot of structural components.
Not necessarily :)
For one thing the amount of "parts" available for the XB-70 was well known. There was enough for TWO aircraft and parts for a "third" but not enough to make a whole new aircraft.

You can look at the size difference between the T/A-4J and the XB-70 and figure the size of crew needed. Add to that even if the carrier was "based" on XB-70 parts how much re-manufacturing and building-from-scratch would have to be done to convert a bomber into a carrier aircraft. (Sure the bombays were between the engines but the XOV was bigger than anything the XB-70 was designed to carry and since it was "semi-conformal" meaning "buried" in there the engine ducting would have to be moved and THAT would have greatly effected the engines performance. I could go on... :) )

Point though; There is/was no "British Supersonic Delta-Wing bomber" built. Are you thinking the subsonic Vulcan?

Further on the Tu-95 Bear as a carrier aircraft I recall that Len Cormier had a concept of a "Bear-Cub" RLV launched from a modified Bear. I believe the website "tour2space" is still up but I can't find it from this computer so I could be wrong.

Quote from: john smith19
Personally I still prefer internal carriage from an OTS transport aircraft that requires *no* modifications. The air drop and ignition of an 89000lb Minuteman stage from the back of a C5 in 1974 pretty much ended the argument for me. How to make maximum *effective* use of the space in the cargo plane of your choice is still an open question.
The main "argument" is that such aircraft are primarily "military" aircraft and kind of hard to get ahold of for civilian use :)

While civilian versions of the C-130 and An-22 (to name a few) are available for lease or purchase the amount of actual "use" as a LV carrier are somewhat limited by availabilty and payload.

The C-130 (actually L-100 as the "civilian" version, the L-100-30 or Model 382G as the most recent version is/was known) can carry about 51,050 lb (23,150 kg).

The AN-22 can carry larger payloads, (up to 80,000 kg/176,350 lb) but you have a more limited "pool" to draw from and the parts and spares situation due to the fewer airframes built/supported is going to be an issue.
(Interestingly, the Douglas C-133 is comparable to the AN-22 in cargo capacity being able to carry around  110,000 lb/50,000 kg and there are still several in the "Boneyard" last time I looked. Though I'll note that while some C-133A's were "retained" by Cargomaster Corporation of Alaska for "civilian" use they were never certified by the FAA so there may be an issue with that)

In contrast "non-military" civil air freighters which can't be used for "air-launch" without modification are actually more numerous and carry substantially more "payload" available for an LV.

You wrote:
Quote
How to make maximum *effective* use of the space in the cargo plane of your choice is still an open question
Which begs the question of what exactly do you MEAN by this? Are we talking how to extract the LV? How big an LV to make? How to possibly use the maximum payload by space and/or mass?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline john smith 19

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Re: Jet Powered First Stage
« Reply #77 on: 09/26/2011 09:12 pm »
Point though; There is/was no "British Supersonic Delta-Wing bomber" built. Are you thinking the subsonic Vulcan?
Yes it *looked* like it should have been supersonic (as did the Victor) and did carry a Concorde test engine, but none of the V bombers were. The nearest modern aircraft meeting that description would have been the Panavia Tornado.
Quote
Further on the Tu-95 Bear as a carrier aircraft I recall that Len Cormier had a concept of a "Bear-Cub" RLV launched from a modified Bear. I believe the website "tour2space" is still up but I can't find it from this computer so I could be wrong.

Quote from: john smith19
Personally I still prefer internal carriage from an OTS transport aircraft that requires *no* modifications. The air drop and ignition of an 89000lb Minuteman stage from the back of a C5 in 1974 pretty much ended the argument for me. How to make maximum *effective* use of the space in the cargo plane of your choice is still an open question.
The main "argument" is that such aircraft are primarily "military" aircraft and kind of hard to get a hold of for civilian use :)

While civilian versions of the C-130 and An-22 (to name a few) are available for lease or purchase the amount of actual "use" as a LV carrier are somewhat limited by availabilty and payload.

The C-130 (actually L-100 as the "civilian" version, the L-100-30 or Model 382G as the most recent version is/was known) can carry about 51,050 lb (23,150 kg).

The AN-22 can carry larger payloads, (up to 80,000 kg/176,350 lb) but you have a more limited "pool" to draw from and the parts and spares situation due to the fewer airframes built/supported is going to be an issue.
(Interestingly, the Douglas C-133 is comparable to the AN-22 in cargo capacity being able to carry around  110,000 lb/50,000 kg and there are still several in the "Boneyard" last time I looked. Though I'll note that while some C-133A's were "retained" by Cargomaster Corporation of Alaska for "civilian" use they were never certified by the FAA so there may be an issue with that)

In contrast "non-military" civil air freighters which can't be used for "air-launch" without modification are actually more numerous and carry substantially more "payload" available for an LV.

In terms of numbers a civilian version is always likely to be more numerous.
The C-133 looked very big. I suspect that it suffered in an era when *everything* needed to be jet powered people were disappointed so sleek an airframe had propellers on it. BTW it seems to have had a problem with fatigue as its original design life was 10 000 (certified to 19000), which seems quite short. I thought Western combat aircraft were rated to over 20 000 hrs and I'd expect a transport to be flying a *lot* more often than a combat plane.

BTW the C17 *might* be available for use

http://en.wikipedia.org/wiki/Commercial_Application_of_Military_Airlift_Aircraft

Quote
You wrote:
Quote
How to make maximum *effective* use of the space in the cargo plane of your choice is still an open question
Which begs the question of what exactly do you MEAN by this? Are we talking how to extract the LV? How big an LV to make? How to possibly use the maximum payload by space and/or mass?

Most of the modern big lifter aircraft seem to have rectangular cargo areas. The obvious design for an ELV is a cylinder fitting inside the square defined (usually) by the internal cabin height. The questions are 1) Is the vehicle mass limited? 2) If not can you find some *other* design that improves economics over and above the basic cylindrical ELV and fill up some of that "empty" space?

The joker in this pack is that better re-use (EG fully RLV) is *likely* to raise development costs when the point of air launch was to *lower* them, but gives you (potentially) a salable product, rather than a 1 off service, as the *whole* system comes back, allowing ongoing refinement and reliability improvement, *the* reason for the launch industries *obsession* with "pedigree" in terms of flight history and launch success.

A first cut would be a TSTO with low wings to try to shield the body as much as possible on re-entry. The nose fairing to have an "aerodisk" like the Trident missiles to improve the packing factor (On Trident it extends 0.8 body diameters and cut drag at shallow angles of attack by 50%) and like the rest of the design be reusable. 

The 1st stage would be tricky as you need something to give it a nose when it reenters, unless it returns with a flat nose, which is likely to get *hot* and you need *maximum* commonality to limit development and mfg costs.

But can you get sufficient lift out of the available wing area to get each stage to a recovery site?

A bolder concept would be an SSTO with the cross section of an SR71 fuselage, with the chine volume either acting as tankage or generating lift for recovery back at base.

My feeling is that this is an area where multiple models (launch price, payload size and mass, launch rate, development budget) intersect to define capabilities and another set to define a market. If you could find a rock solid market and price point that would become the driver.

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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #78 on: 09/28/2011 08:45 pm »
The main "argument" is that such aircraft are primarily "military" aircraft and kind of hard to get a hold of for civilian use ....

In contrast "non-military" civil air freighters which can't be used for "air-launch" without modification are actually more numerous and carry substantially more "payload" available for an LV.

In terms of numbers a civilian version is always likely to be more numerous.
Civilian "versions"? I didn't mean more civilian "versions" of military craft though there are actual examples such as I showed the ACTUAL number of "civilian" military-cargo type aircraft usually are much smaller in number than their actual military types. This is only different if the original military model is retired from service and becomes available to and for civilian use.

My actual point was there are more civilian 707, 747, AirBus, etc freight haulers than there are dedicated military cargo aircraft :)

Unfortunatly "internal-carry" for air-launch isn't possible with the way they are laid out unless major modifications to the airframe are done.

Quote
The C-133 looked very big. I suspect that it suffered in an era when *everything* needed to be jet powered people were disappointed so sleek an airframe had propellers on it. BTW it seems to have had a problem with fatigue as its original design life was 10 000 (certified to 19000), which seems quite short. I thought Western combat aircraft were rated to over 20 000 hrs and I'd expect a transport to be flying a *lot* more often than a combat plane.
IIRC there may have been an issue with the propellers going supersonic and the subsequent shockwaves impinging on the pressure hull causing cracks. I suspect that might actually be the main reason that the FAA is withholding certification but there isn't any way to really know.

On the other hand I've heard that there is some "commonality" between the props of the C-133 and C-130 and if the newer model ("J") high-sonic blades could be fitted this would elminate the issue.

And yes it IS big :) Fitting with being the first "strat-lifter" the AF had it has a cargo hold measuring 86 feet, 10 inches long and 20 feet in diameter capable of carrying any piece of equipment the Army owned in the late-60s and all of our deployed missiles. (Comparativly the C5 cargo bay is 121 feet long, 19 feet wide and 13 feet high)

Quote
BTW the C17 *might* be available for use

http://en.wikipedia.org/wiki/Commercial_Application_of_Military_Airlift_Aircraft
Currently the production is totally used up by government requirements. Even if there is commercial interest as indicated in the cited article, production is currently "behind" on providing military aircraft and Congress is constantly theatening to shut down production, or reduce the number ordered or a dozen other silly ideas which isn't helping the situation any.

In other words I'll believe it when I see it :)

However for "completness":
C-17 maximum payload is 169,000lbs, and it's cargo area measures 88-feet long, 18-feet wide, and 12-foot-4-inches forward of the wing to 13-feet-6-inches aft of the wing.

Quote
You wrote:
Quote
How to make maximum *effective* use of the space in the cargo plane of your choice is still an open question
Which begs the question of what exactly do you MEAN by this? Are we talking how to extract the LV? How big an LV to make? How to possibly use the maximum payload by space and/or mass?
Quote
Most of the modern big lifter aircraft seem to have rectangular cargo areas. The obvious design for an ELV is a cylinder fitting inside the square defined (usually) by the internal cabin height. The questions are 1) Is the vehicle mass limited? 2) If not can you find some *other* design that improves economics over and above the basic cylindrical ELV and fill up some of that "empty" space?

1) Mostly "yes" from what I gather. As an example the "SwiftLaunch" vehicle proposed here:
http://mae.ucdavis.edu/faculty/sarigul/aiaa2001-4619.pdf

Is 89-feet long and less than 20-feet wide with the LV and Transporter/Sled estimated to mass 290,000lbs. (That's a little under 1,000lbs shy of the C-5's Maximum WARTIME loading by the way)

On the other hand AirLaunch states here:
http://www.airlaunchllc.com/AirLaunch%20Small%20Sat%20Paper%20SSC07-III-3%20w-Attachment%20A.pdf

(Gary will correct me if I wrong... I hope :) ) That their "full-up" weight of the QuickReach LV is around 72,000lbs, however it's "length-restricted" due to the launch method so that the nose will clear the tail-overhead upon drop. With 169,000lbs of "payload" you could stick another QuickReach on-board if you were only worried about mass.

A LOT depends on how you are "extracting" your LV as well as the overall mass too. Getting the LV out of the aircraft in a fast but safe way is probably a large driver of your LV size, you on-board support needs and will dictate some of the design constraints you'll face putting together an LV concept. Which seems to have answered number 2 :)

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The joker in this pack is that better re-use (EG fully RLV) is *likely* to raise development costs when the point of air launch was to *lower* them, but gives you (potentially) a salable product, rather than a 1 off service, as the *whole* system comes back, allowing ongoing refinement and reliability improvement, *the* reason for the launch industries *obsession* with "pedigree" in terms of flight history and launch success.

Actually I've always considered the MAIN point of Air-Launch is the possibilty of lowering OPERATIONS costs rather than development costs as aircraft operations costs are fairly predictable and have a much deeper repair/maintenance/operations history to draw upon.

The ability to move to adjust launch azimith and orbital tracks is a bonus as is the ability to launch over water and of course flexability.

I'm afraid that fact that no one has stepped forward to fund a QuickReach launch and/or the lack of flights for Pegasus might say more about the general utility and percieved "usefullness" of Air Launch than I'd really like to hear.

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A first cut would be a TSTO with low wings to try to shield the body as much as possible on re-entry. The nose fairing to have an "aerodisk" like the Trident missiles to improve the packing factor (On Trident it extends 0.8 body diameters and cut drag at shallow angles of attack by 50%) and like the rest of the design be reusable.
"Aerodisk"? The Trident has an "Aerodynamic Spike" which gets shortened (and then confused) to "Aero-Spike" which means people get it confused with the similar Aerospike rocket engine. Never heard it called an "aerodisk" before.

However, given that the "tip" actually IS a fairly flat "disk"
(Page 44 of this report: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790014372_1979014372.pdf ) I can see why that term might make sense.

So if I understand the idea you want a deployable system to improve the initial aerodynamics of the vehicle so you can keep the "fairing" more compact?

I'm going to jump-on-my-soapbox for a second 'cause you hit a "pet-peeve" of mine: Wings are NOT required for reusability!!!!

A cylinder, cone, or lifting-body shape are just as adequate for reentry control and "lift" during hypersonic flight during reentery and sub-sonic and landing can be accomplished using a para-foil or simple parachutes. Landing "gear" if you really "insist" but even that's not actually a "given" mass requirement. One of the MOST under-appreciated and under-studied designs for a spacecraft is the "Spacecruiser" concept:
http://www.astronautix.com/craft/spauiser.htm
http://www.up-ship.com/apr/extras/scruiser1.htm
http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADB143755
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADB143755&Location=U2&doc=GetTRDoc.pdf

(Flattened out and upsized it begins to look far to much like the spaceship from "Planet-of-the-Apes" to me but that might actually be a "selling" point if you think about it ;) )

The main point still, is that wings are only "needed" if you decide you want them, not that they are actually REQUIRED. (Stepping off the soap-box now :) )

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The 1st stage would be tricky as you need something to give it a nose when it reenters, unless it returns with a flat nose, which is likely to get *hot* and you need *maximum* commonality to limit development and mfg costs.
You don't want a low-drag nose on reentry, you WANT a fairly low angle or near-flat surface to induce a seperation shock. That's why most early spacecraft used "blunt" reentery faces. Even the Shuttle entered at a very high Angle-of-Attack to present the most surface are and drag on reentry. Point of fact is that more aerodynamic shapes get "hotter" at high speeds than blunt surfaces because the aerodynamic shapes don't tend to create the seperation shocks needed to have the aero-plasma stand off the skin far enough.

As for "commonality" the question would be "with-what?" High "commonality" with your launch system? Everyones launch system? I'm not following exactly what you intend here.

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But can you get sufficient lift out of the available wing area to get each stage to a recovery site?
That depends, because you don't KNOW what your "recovery" site is and if you are going to develop a TRUELY flexible Air Launch system you may not HAVE a convinient "recovery" site available. There are options however;

You can fly to a spot "up-range" of your recovery site and launch the LV there and "glide-forward" to the recovery area. You can have a large helicopter down-range to "air-snatch" your booster as it parachutes down which is a proven concept. You can station a barge or ship down-range and have the booster "steer" to a landing on that. And there are other ways of adjusting the details of the mission architecture. First though you have to really define both the vehicle AND the way it performs the overall mission to know what you have to work with.

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A bolder concept would be an SSTO with the cross section of an SR71 fuselage, with the chine volume either acting as tankage or generating lift for recovery back at base.
"Bolder" yes, also tougher and much, much more technically challenging. Note that the "SwiftLaunch" concept is actually a 1.5-STO with an expendable "drop-tank" so it's not that much more difficult to envision a pure SSTO version. Envisioning such a vehicle with any actual "payload" may be more problematical though :)

The "chine" size would limit its utility for propellant but it WOULD automatically generate a lift vector. (Similar to the Spacecruiser above) Given the restriction(s) on space due to internal carry it may be the ONLY method of gaining lift for the vehicle.

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My feeling is that this is an area where multiple models (launch price, payload size and mass, launch rate, development budget) intersect to define capabilities and another set to define a market. If you could find a rock solid market and price point that would become the driver.
There in lies one of the major problems though, how do you FIND that "market" and price-point since you need to have a market to survey to GET a price point? As noted earlier, it's the whole chicken-and/or-the-egg thing all over again.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline HMXHMX

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Re: Jet Powered First Stage
« Reply #79 on: 09/30/2011 05:27 pm »
QuickReach was 72K lbm at startburn.  One of our early bids proposed carrying two, side by side, but USAF wouldn't approve that, for reasons that later appear to be wrong (relating to off centerline drop mass limits).

Offline Epis

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Re: Jet Powered First Stage
« Reply #80 on: 10/02/2011 09:53 am »
lets take a look in to the future 5 years by now where spaceX reusable F9 starts to fly and offers price as low as ~ 150-200 $/kg for LEO transport.

Question is simple will Jet powered First Stage be competitive ?
could offer lower price ?

latest paper by nasa that was in this forum posted about horizontal launch research using airplane launch assist projected price about ~3000 $/kg to LEO transport that is no competition to reusable F9 rocket, so I suppose Plane launch assist is out of the game. Skylon could in future make some competition to reusable 2 stage rockets.

and of course this is where my political point of view shines, that future of  LEO transportation will be all about energy efficiency, just look at numbers if F9 rocket fuel cost 20$/kg LEO cargo ( F9 propellant cost 200 000$ and payload 10 000kg then 200 000/10 000 = 20$/kg. ) so if Leo transport price drops as low as 100$/kg fuel price will be 20% of cost (today it is insignificant ~0.5%) and if skylon will show up it will have even higher fuel price % about 30-40% of LEO cost, so trend is clear there,  that fuel cost of LEO transport of RLV will be significant final part of the cost. so the race of fuel reduction will begin.
by 10-15 years from now when reusable F9 rocket will create new space market boom and demand will reach reusable F9 rocket service capacity (all other Leo transport payers will bankrupt, unless will introduce their own RLV vehicles)  the market condition and demand volume will be the right for new style mountain slope Launch assist development that will slash energy consumption by from 1/3  till 2/3 making fuel cost as low as 7-13$/kg and new style of reusable SSTO vehicles that could service for more than 1000 entry/reentry cycles could reach cost reduction of LEO lower than 50$/kg to orbit. 
So what I am speaking here is that after introduction of reusable space launch transport next innovation steps are in propellant less launch assist systems, that will cut dramatically energy/fuel consumption.
start think of Ramjet engines that ride along track and ingest most of its fuel (80-90%) externally by on track mountain slope spraying system combined with maglev start up electric accelerator till 70-100m/s speed to start that engine, or different engine types.. 

Online sanman

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Re: Jet Powered First Stage
« Reply #81 on: 10/05/2011 05:29 am »
At the most basic level, the difference between a jet and a rocket is that the jet sources its oxidizer from the surrounding air, while the rocket gets it from an onboard supply.

Using the SpaceX Grasshopper First Stage as an example, how much launch mass would be saved if that first stage were to source available oxidizer from the surrounding air during its transit through the atmosphere? Obviously that first stage would have to use onboard oxidizer for the rest of the trip up, beyond the atmosphere.

Offline Epis

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Re: Jet Powered First Stage
« Reply #82 on: 10/05/2011 09:36 am »
At the most basic level, the difference between a jet and a rocket is that the jet sources its oxidizer from the surrounding air, while the rocket gets it from an onboard supply.

Using the SpaceX Grasshopper First Stage as an example, how much launch mass would be saved if that first stage were to source available oxidizer from the surrounding air during its transit through the atmosphere? Obviously that first stage would have to use onboard oxidizer for the rest of the trip up, beyond the atmosphere.
quick answer could be such if F9 first stage fuel volume would be approximately 2/3 of all rocket mass that would be ~222 tons. then if 1 stage engine burning time is 150s, and rocket has Max-q pressure at 76 second basically that is half of 1 stage launch time, so if ~75% of fuel is LOX then 222/2*0.75=83.25 Tons of Lox could be saved if taken from atmosphere.
now if we place Jet engines with 5MN thrust (with 9 T/W ratio) engines would weight 500/9=55.5 Tons  and it could save 28 tons of LOX in such simple scenario, its not much, and ability to boost rocket for 76s at 5MN thrust is in question ?  so I guess that this 28T lox saving will be eaten away  after reaching >12-15km altitude level where atmosphere density start sharply decrease 5-10x so I guess thous 28T of oxygen would be needed to extend flight time.
in the end advantage if is, is so small, then whats a point ?

Offline Jim

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Re: Jet Powered First Stage
« Reply #83 on: 10/05/2011 11:39 am »

in the end advantage if is, is so small, then whats a point ?

Much like your other launch assist ideas

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #84 on: 10/07/2011 05:24 pm »
QuickReach was 72K lbm at startburn.  One of our early bids proposed carrying two, side by side, but USAF wouldn't approve that, for reasons that later appear to be wrong (relating to off centerline drop mass limits).
However the Air Force does neither denies nor confirms that is has EVER been wrong as far as they know... ;)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline HMXHMX

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Re: Jet Powered First Stage
« Reply #85 on: 10/08/2011 05:19 am »
QuickReach was 72K lbm at startburn.  One of our early bids proposed carrying two, side by side, but USAF wouldn't approve that, for reasons that later appear to be wrong (relating to off centerline drop mass limits).
However the Air Force does neither denies nor confirms that is has EVER been wrong as far as they know... ;)

Randy

Yeah, you are not talking to a big USAF fan, here.  I wasn't amused that they spent a year or more making us jump though multi million dollar hoops (on a fixed price contract) to prove our 72K drop wouldn't break the airplane, when in fact the load we put on the ramp was only about 2/3rds that a normal 60K pallet drop imposes (has to do with where the Cg of the load is at release).  And then they cavalierly dropped a heavier load (Ares chute test article) without much fuss.

Offline john smith 19

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Re: Jet Powered First Stage
« Reply #86 on: 10/11/2011 11:34 pm »
Civilian "versions"? I didn't mean more civilian "versions" of military craft though there are actual examples such as I showed the ACTUAL number of "civilian" military-cargo type aircraft usually are much smaller in number than their actual military types. This is only different if the original military model is retired from service and becomes available to and for civilian use.
Poor use of English. I meant freighter versions of commercial passenger carriers would *always* be more numerous than military transports.

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Unfortunatly "internal-carry" for air-launch isn't possible with the way they are laid out unless major modifications to the airframe are done.
Yes. That's the problem. I guess making the rear loading door openable in flight (even at altitudes of 100s, not 1000s of metres) really is *that* big a deal.

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IIRC there may have been an issue with the propellers going supersonic and the subsequent shockwaves impinging on the pressure hull causing cracks. I suspect that might actually be the main reason that the FAA is withholding certification but there isn't any way to really know.
I heard of a British aircraft that did this in the late 1940s. The noise was meant to be horrific. I don't think it lasted in service long enough for anyone to know what effect the noise had on the airframe. The obvious answer, multiple high pressure pulses every second would be "not good."
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On the other hand I've heard that there is some "commonality" between the props of the C-133 and C-130 and if the newer model ("J") high-sonic blades could be fitted this would elminate the issue.
Assuming the damage hasn't been done already. Otherwise I guess it's looking at a complete overhaul (*if* that's even possible).
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And yes it IS big :) Fitting with being the first "strat-lifter" the AF had it has a cargo hold measuring 86 feet, 10 inches long and 20 feet in diameter capable of carrying any piece of equipment the Army owned in the late-60s and all of our deployed missiles. (Comparativly the C5 cargo bay is 121 feet long, 19 feet wide and 13 feet high)
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I'd say the fact the bay is more nearly circular is a nice plus point.
A LOT depends on how you are "extracting" your LV as well as the overall mass too. Getting the LV out of the aircraft in a fast but safe way is probably a large driver of your LV size, you on-board support needs and will dictate some of the design constraints you'll face putting together an LV concept. Which seems to have answered number 2 :)
One of the more subtle points of the launch mode. It implies something able to generate a serious amount of force for a short period to get the LV out the back.

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The joker in this pack is that better re-use (EG fully RLV) is *likely* to raise development costs when the point of air launch was to *lower* them, but gives you (potentially) a salable product, rather than a 1 off service, as the *whole* system comes back, allowing ongoing refinement and reliability improvement, *the* reason for the launch industries *obsession* with "pedigree" in terms of flight history and launch success.
However, given that the "tip" actually IS a fairly flat "disk"
(Page 44 of this report: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790014372_1979014372.pdf ) I can see why that term might make sense.

So if I understand the idea you want a deployable system to improve the initial aerodynamics of the vehicle so you can keep the "fairing" more compact?
[/quote]
I can't remember if I saw the term either in report in one of the Space Mechanisms conference proceedings (which I think is what you've cited) or an independent analysis done (IIRC) in Australia.

Conventional fairings tend to need a length of several LV diameters (the Haack low drag typically needs about 5x LV dia) whereas the aerodisk on Trident was <0.8Dia long, giving something like a folded Pitot tube plus c25cm to allow for the disk on the end. The aim was minimum length, maximum cross sectional area for both payload and tank. I'm not saying you could not use *part* of the fairing length as the top end of the tank, only that it's *difficult*.

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I'm going to jump-on-my-soapbox for a second 'cause you hit a "pet-peeve" of mine: Wings are NOT required for reusability!!!!

A cylinder, cone, or lifting-body shape are just as adequate for reentry control and "lift" during hypersonic flight during reentery and sub-sonic and landing can be accomplished using a para-foil or simple parachutes. Landing "gear" if you really "insist" but even that's not actually a "given" mass requirement. One of the MOST under-appreciated and under-studied designs for a spacecraft is the "Spacecruiser" concept:
http://www.astronautix.com/craft/spauiser.htm
http://www.up-ship.com/apr/extras/scruiser1.htm
http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADB143755
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADB143755&Location=U2&doc=GetTRDoc.pdf

(Flattened out and upsized it begins to look far to much like the spaceship from "Planet-of-the-Apes" to me but that might actually be a "selling" point if you think about it ;) )

The main point still, is that wings are only "needed" if you decide you want them, not that they are actually REQUIRED. (Stepping off the soap-box now :) )
I *totally* agree with you. I'm aware of multiple RV tests starting with ASSET and PRIME (even Gemini)in the 60's which have demonstrated effective maneuvering and lift with out wings. My favorite was the eccentrically weighted ring which could be rotated off the keel line, needing *no* exposure to the airflow to achieve control and lift.

The wing/body approach is simple and likely to be cheaper to construct, but it was an off the top of the head idea.

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The 1st stage would be tricky as you need something to give it a nose when it reenters, unless it returns with a flat nose, which is likely to get *hot* and you need *maximum* commonality to limit development and mfg costs.
Quote
You don't want a low-drag nose on reentry, you WANT a fairly low angle or near-flat surface to induce a seperation shock. That's why most early spacecraft used "blunt" reentery faces. Even the Shuttle entered at a very high Angle-of-Attack to present the most surface are and drag on reentry. Point of fact is that more aerodynamic shapes get "hotter" at high speeds than blunt surfaces because the aerodynamic shapes don't tend to create the seperation shocks needed to have the aero-plasma stand off the skin far enough.
True. The recent Spacex animation of their planned TSTO RLV upgrade to the Falcon 9 does this. I'm thinking about the interstage skirt and weather it's inside or outside the shock. My intuition is that edge could get quite warm. The 2nd stage re-entry put me in mind of TGV's "Michelle b" proposal, especially what looked like a drag brake between the landing legs.


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As for "commonality" the question would be "with-what?" High "commonality" with your launch system? Everyones launch system? I'm not following exactly what you intend here.
Something that came up in various bimese projects in the 1960's was the point at which 2 stages which are designed to be *identical* (and hence can be developed for the price of 1) become *so* different (because people prize performance at nearly any price and have "tweaked" them) that you have to have 2 *separate* budgets for what are now 2 separate stages.

It's an issue the Reaction Engines team are familiar with and was one of the drivers for Skylon. Some of them worked on something called MUSTARD. Commonality between the 2 stages in terms of both size and layout.

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But can you get sufficient lift out of the available wing area to get each stage to a recovery site?
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That depends, because you don't KNOW what your "recovery" site is and if you are going to develop a TRULY flexible Air Launch system you may not HAVE a convenient "recovery" site available. There are options however;

You can fly to a spot "up-range" of your recovery site and launch the LV there and "glide-forward" to the recovery area. You can have a large helicopter down-range to "air-snatch" your booster as it parachutes down which is a proven concept. You can station a barge or ship down-range and have the booster "steer" to a landing on that. And there are other ways of adjusting the details of the mission architecture. First though you have to really define both the vehicle AND the way it performs the overall mission to know what you have to work with.
OMG. I can't believe I completely missed the up range tactic. Dropping the returning stage *near* the recoery area instead of down range in the middle of an ocean or desert is *so* obvious.
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The "chine" size would limit its utility for propellant but it WOULD automatically generate a lift vector. (Similar to the Spacecruiser above) Given the restriction(s) on space due to internal carry it may be the ONLY method of gaining lift for the vehicle.

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My feeling is that this is an area where multiple models (launch price, payload size and mass, launch rate, development budget) intersect to define capabilities and another set to define a market. If you could find a rock solid market and price point that would become the driver.
There in lies one of the major problems though, how do you FIND that "market" and price-point since you need to have a market to survey to GET a price point? As noted earlier, it's the whole chicken-and/or-the-egg thing all over again.
There is a price elasticity study done by someone in Georgetown (it's on my hard drive *somewhere*) which indicates the price elasticity in the launch market is *very* poor. A 50% reduction (as the EELV programme was designed to give the DoD) just does not cut it IRL.

It seems something like a 10x reduction is needed before *serious* growth is seen. Or perhaps the ability to recover *all* of the LV and sell it on to someone else? It turns "We *must* have a launch. It's the only way to get the results we need and we'll swallow the cost" into "It'll give us the results and if it does not work we can either launch again or sell the vehicle and recover most of the cost," which just *sounds* better to fund holders at academic institutions.

BTW the guy who designed Seahorse and started the design-to-cost debate said the brief he was given was exactly this, as "A threefold cost reduction won't do it, that can be swallowed in cost overruns" according to his boss.

The only near term price point I can give is that IIRC a report at one of the smallsat conferences said a group of universities had each pitched in $100k to fly a cubesat on a Russian LV (Rockot?)

I'd guess right now the people most actively pursuing this are Xcorp with their Lynx vehicle, one of whose options is a pod above the cabin that *might* carry an ELV.

They've been saying multiple small markets will give them resilience but obviously they are not keen to talk pricing to anyone without cash on the table.
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline Bob Shaw

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Re: Jet Powered First Stage
« Reply #87 on: 10/24/2011 09:31 pm »
I've scanned and attached below a short article from Spaceflight Vol 1 No 8 - July 1958 which describes an early proposal for a jet powered first stage rather like the early Kistler 'launch platform'.


Bob Shaw
« Last Edit: 10/24/2011 09:34 pm by Bob Shaw »

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #88 on: 10/25/2011 12:53 pm »
Thanks Bob! That pretty much illustrates the concept nicely.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Rocket Science

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Re: Jet Powered First Stage
« Reply #89 on: 10/25/2011 01:12 pm »
Nice example of what I had in mind when I started this thread. Great find, thank you for posting it!

Robert
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #90 on: 10/26/2011 04:57 pm »
And speaking of more modern ideas:

A concept called "AirBooster" or more fully: "AirBooster Air Breathing Zero Stage for Modern Launch Vehicles" which is the title of the video below and here is a snip from the bio also below giving some details on the concept:

"Since the summer of 2008 I have been researching on improving the efficiency of modern rockets by augmenting an air-breathing cycle through various ways. The first stage of all rockets carries its own oxidizer which it primarily burns whilst flying through an air-rich atmosphere. My work focuses on how to burn this air instead of liquid oxygen and hence significantly increase the payload capacity.

The current design accomplishes this task by augmenting standard launch vehicles with an air-breathing zero-stage dubbed AirBooster. The AirBooster in essence is a fuel tank surrounded by afterburning hybrid turbofan/ramjet engines capable of reaching velocity of Mach 3.2 (P&W J58 for instance). The AirBooster attaches below a launch vehicle with a specially made inter-stage and jettisons from the main vehicle upon burn-out (at an approximate altitude of 8km). As the rocket continues in its normal regime, the AirBooster deploys several parachutes to slow down and land on water where it stays afloat via airbags. With the added boost a significant portion of fuel in the second stage of the main rocket will remain un-burnt upon reaching the required orbit. The un-burnt fuel mass translates into additional payload mass. Theory predicts such boost would double the payload capacity with minimal modifications to the launch vehicle and consequently, instead of two flights, only one is required."

(Note on the web that this had/has a provisional patent as of 2009 but I can't find anything on it)

Links:
http://wn.com/Airbreathing_jet_engine

http://stevens.usc.edu/read_article.php?news_id=514

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #91 on: 10/27/2011 05:30 pm »
Unfortunatly "internal-carry" for air-launch isn't possible with the way they are laid out unless major modifications to the airframe are done.
Yes. That's the problem. I guess making the rear loading door openable in flight (even at altitudes of 100s, not 1000s of metres) really is *that* big a deal.
Actually the "big" deal is the majority of civilian air-freighters don't HAVE any "rear" loading doors! They "may" have a nose loading door but that's rare so what they USUALLY have is "side" opening doors which are not condusive to "air-dropping" anything.

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I'd say the fact the bay is more nearly circular is a nice plus point.
A LOT depends on how you are "extracting" your LV as well as the overall mass too. Getting the LV out of the aircraft in a fast but safe way is probably a large driver of your LV size, you on-board support needs and will dictate some of the design constraints you'll face putting together an LV concept. Which seems to have answered number 2 :)
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One of the more subtle points of the launch mode. It implies something able to generate a serious amount of force for a short period to get the LV out the back.
In some (probably best) cases yes, AirLaunch didn't bother and simply used a small parachute to extract and stabilize the rocket while gravity caused it to pitch up as it rolled out of the C-17. The downside for this is this is going to restrict your LV size so as the clear the top of the cabin and tail boom.

The afore mentioned "Quick-Reach" used the proven method of parachutes to extract the LV attached to a sled/vehicle supporter using the "standard" air-drop procedures. Pretty much the same method but with a more advanced and powerful LV and optimized sled that was used to test launch a MinuteMan missile from a C-5 in the 80s.

There was a Russian proposal using a pneumatic launch tube mounted inside the carrier aircraft and a compressed air charge too blow it out the back, but this cuts into your Carrier aircraft capacity and it much more complex (and probably riskyer) than using parachutes.

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So if I understand the idea you want a deployable system to improve the initial aerodynamics of the vehicle so you can keep the "fairing" more compact?
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Conventional fairings tend to need a length of several LV diameters (the Haack low drag typically needs about 5x LV dia) whereas the aerodisk on Trident was <0.8Dia long, giving something like a folded Pitot tube plus c25cm to allow for the disk on the end. The aim was minimum length, maximum cross sectional area for both payload and tank. I'm not saying you could not use *part* of the fairing length as the top end of the tank, only that it's *difficult*.
Ok

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The main point still, is that wings are only "needed" if you decide you want them, not that they are actually REQUIRED. (Stepping off the soap-box now :) )
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I *totally* agree with you. I'm aware of multiple RV tests starting with ASSET and PRIME (even Gemini)in the 60's which have demonstrated effective maneuvering and lift with out wings. My favorite was the eccentrically weighted ring which could be rotated off the keel line, needing *no* exposure to the airflow to achieve control and lift.

The wing/body approach is simple and likely to be cheaper to construct, but it was an off the top of the head idea.
Ok, as long as my opinion is validated we can move on ;)

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As for "commonality" the question would be "with-what?" High "commonality" with your launch system? Everyones launch system? I'm not following exactly what you intend here.
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Something that came up in various bimese projects in the 1960's was the point at which 2 stages which are designed to be *identical* (and hence can be developed for the price of 1) become *so* different (because people prize performance at nearly any price and have "tweaked" them) that you have to have 2 *separate* budgets for what are now 2 separate stages.

It's an issue the Reaction Engines team are familiar with and was one of the drivers for Skylon. Some of them worked on something called MUSTARD. Commonality between the 2 stages in terms of both size and layout.
Actually MUSTARD was a tri-mese design at the very least but I get you're point. The thing is though that in reality when you go for multiple "stages" as vehicles then the "one" you want commenality with is the Orbiter, so they all pretty much end up being copies of the Orbiter with all the expensive hardware and equipment that entails.

Anything less for any of them and you're getting back into making seperate vehicles again.

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But can you get sufficient lift out of the available wing area to get each stage to a recovery site?
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That depends, because you don't KNOW what your "recovery" site is and if you are going to develop a TRULY flexible Air Launch system you may not HAVE a convenient "recovery" site available. There are options however;

You can fly to a spot "up-range" of your recovery site and launch the LV there and "glide-forward" to the recovery area. You can have a large helicopter down-range to "air-snatch" your booster as it parachutes down which is a proven concept. You can station a barge or ship down-range and have the booster "steer" to a landing on that. And there are other ways of adjusting the details of the mission architecture. First though you have to really define both the vehicle AND the way it performs the overall mission to know what you have to work with.
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OMG. I can't believe I completely missed the up range tactic. Dropping the returning stage *near* the recovery area instead of down range in the middle of an ocean or desert is *so* obvious.
No biggie :) "I" did the face-palm when I was reminded about it too... It's on of those really "obvious" advantages to Air-Launch that are way to easy to forget about :)

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My feeling is that this is an area where multiple models (launch price, payload size and mass, launch rate, development budget) intersect to define capabilities and another set to define a market. If you could find a rock solid market and price point that would become the driver.
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There in lies one of the major problems though, how do you FIND that "market" and price-point since you need to have a market to survey to GET a price point? As noted earlier, it's the whole chicken-and/or-the-egg thing all over again.
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There is a price elasticity study done by someone in Georgetown (it's on my hard drive *somewhere*) which indicates the price elasticity in the launch market is *very* poor. A 50% reduction (as the EELV programme was designed to give the DoD) just does not cut it IRL.

It seems something like a 10x reduction is needed before *serious* growth is seen. Or perhaps the ability to recover *all* of the LV and sell it on to someone else? It turns "We *must* have a launch. It's the only way to get the results we need and we'll swallow the cost" into "It'll give us the results and if it does not work we can either launch again or sell the vehicle and recover most of the cost," which just *sounds* better to fund holders at academic institutions.

BTW the guy who designed Seahorse and started the design-to-cost debate said the brief he was given was exactly this, as "A threefold cost reduction won't do it, that can be swallowed in cost overruns" according to his boss.

The only near term price point I can give is that IIRC a report at one of the smallsat conferences said a group of universities had each pitched in $100k to fly a cubesat on a Russian LV (Rockot?)

I'd guess right now the people most actively pursuing this are Xcorp with their Lynx vehicle, one of whose options is a pod above the cabin that *might* carry an ELV.

They've been saying multiple small markets will give them resilience but obviously they are not keen to talk pricing to anyone without cash on the table.
At this point it would probably be pretty hard to nail down numbers I suppose. Though it's interesting how many people out there are suddenly chasing the micro/nano-sat market, especially with air-launch ideas.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline HMXHMX

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Re: Jet Powered First Stage
« Reply #92 on: 10/27/2011 10:08 pm »
Just a minor point.  The QuickReach extraction is done by gravity, not the parachute.  The C-17 flew at a deck angle of 6 degrees and that is sufficient to do the trick.  The parachute was there to control pitch rate and lock up the ignition attitude.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #93 on: 10/31/2011 03:20 pm »
Just a minor point.  The QuickReach extraction is done by gravity, not the parachute.  The C-17 flew at a deck angle of 6 degrees and that is sufficient to do the trick.  The parachute was there to control pitch rate and lock up the ignition attitude.
Thanks for the correction!

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Carreidas 160

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Re: Jet Powered First Stage
« Reply #94 on: 12/13/2011 10:07 pm »
Shit just got real! (Well, a bit less speculative at least...) Go Burt & Paul!

http://www.stratolaunch.com/

Offline deltaV

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Re: Jet Powered First Stage
« Reply #95 on: 12/13/2011 10:27 pm »
crap just got real! (Well, a bit less speculative at least...) Go Burt & Paul!

http://www.stratolaunch.com/
That's being discussed in another thread:
http://forum.nasaspaceflight.com/index.php?topic=27520.0

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #96 on: 12/14/2011 07:49 pm »
Going to post this here instead of the "StratoLaunch" thread to diversify things :)

The Crossbow Air-Launch-To-Orbit concept:
http://eddy.nps.edu/IDDR/techMatrixPages/3d/crossbow/crossbow.html

"Crossbow" = Cargo ROcket Space System BOx Wing

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #97 on: 02/19/2013 04:05 pm »
Necro-threading I know, but interesting tibbit...

NASA (specifically Dryden) seems to have at least some interest in the concept of Jet/Air-breathing Launch assist. Enough so that they have a design in mind:
Ram-Booster
http://www.nasa.gov/offices/ipp/centers/dfrc/technology/DRC-010-039-Ram-Booster.html

on which they took out a patent:
http://www.freepatentsonline.com/8047472.pdf

Consisting of a three stage design: first stage is powered by up to 18 low-bypass military turbofan engines which gets the vehicle up to around Mach-2.6 and around 40,000ft. The second stage uses a set of 15 reusable ramjet engines to go from Mach-2 to Mach-4 at 100,000ft where stage 3, a heavily modified duel engine Centaur III takes the payload to orbit.
The first stage parachutes to a lower altitude and then makes a powered landing, the second stage makes a parachute landing at sea and the 3rd stage is expended.

Even more interesting I found out that the originator of the jet-booster idea is still around and working. Dani Eder has a "Space Transportation and Engineering Methods" book/on-line site in work here:
http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods

Including a section where he address the Jet Engine Launch Assist Concept which is here:
http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods/Human_Transport

He's "updated" the specification on the flight trajectory and staging of the engines from the original. Now the engines are mounted to a "booster-ring" which sounds somewhat similar to Glenn Olson's idea of a dedicated stage instead of individual engine pods as previous. I'm going to write and ask some more detailed questions but the idea sounds much easier for staging as mounting the "upper" stages in the center of the "booster-ring" allows their engines to fire without impacting the turbojets.

In the Dryden design above the second stage ramjets would be impinging on the first stage "struts" and "center-body" after they fire and before seperation. Mounting the jets on a ring around the central body keeps the exhaust clear and allows the ramjet to ramp up to speed without worry about damaging the first stage. (It would also make a much more compact launch vehicle height wise)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Asteroza

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Re: Jet Powered First Stage
« Reply #98 on: 02/20/2013 09:26 am »
A potential problem of the ring type booster is having a clean sliding telescopic stage separation while keeping the ring intact, if the intention is to reduce stack height.

Offline R7

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Re: Jet Powered First Stage
« Reply #99 on: 02/20/2013 12:51 pm »
Jet/Air-breathing Launch assist

Is it worth to include the art of airbreathing jet engines to the picture just to save some of the cheapest resource; propellant. IMO violates the KISS. Ramjet, maybe. Great T/W, simple to manufacture.

edit: otyp
« Last Edit: 02/20/2013 01:10 pm by R7 »
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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #100 on: 02/20/2013 02:52 pm »
A potential problem of the ring type booster is having a clean sliding telescopic stage separation while keeping the ring intact, if the intention is to reduce stack height.
Not really a "problem" though it's a design consideration. There are various methods of seperation that could be used. Struts/Fins could be used since you'd want the ring to "stand-off" the core anyway to provide the jets with 'clean' airflow.

Jet/Air-breathing Launch assist

Is it worth to include the art of airbreathing jet engines to the picture just to save some of the cheapest resource; propellant. IMO violates the KISS. Ramjet, maybe. Great T/W, simple to manufacture.
One thing to keep in mind is that the point isn't "saving" propellant or really replacing some disposable SRBs for a few extra pounds to orbit. What you're doing is using highly reusable, high ISP engines for launch assist. (Jets measure their operation time in hours unlike rocket engines which are minutes at best)

It doesn't "violate" KISS, you're using "simple" jet engines in their best range of use. (Keep it below Mach-3 and you normally can get away with simple inlets and exhausts and no major aerodynamics) And since they are the original "gas-and-go" engines, (so to speak) you can support a much higher flight rate initially.

Ramjets have a good T/W... Once they get going :) But they have to have a "boost" to get up to operations speed. The idea has been suggested to use integral solid boosters to get them up to speed, (and there are several examples of tested and operational engines employing this method) but again, you're looking at having to process the engines and reload them before they can be used again. Effecting your flight rate.

The idea is to have a flight ability similar to a standard aircraft instead of what is usually thought of for a rocket vehicle.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline R7

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Re: Jet Powered First Stage
« Reply #101 on: 02/20/2013 04:59 pm »
One thing to keep in mind is that the point isn't "saving" propellant or really replacing some disposable SRBs for a few extra pounds to orbit. What you're doing is using highly reusable, high ISP engines for launch assist. (Jets measure their operation time in hours unlike rocket engines which are minutes at best)

As you wrote, it's a launch assist system. The whole system needs a rocket anyway. All you accomplish with jets is that your rocket stage can be less massive. Most mass saved is propellant. No reason why a rocket engine can't have cumulative operation time measured in hours. And they have demonstrated that. As far as reusability goes what does a pure jet stage offer that similar purely rocket powered couldn't do? Other than do it with less propellant.

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It doesn't "violate" KISS, you're using "simple" jet engines in their best range of use. (Keep it below Mach-3 and you normally can get away with simple inlets and exhausts and no major aerodynamics) And since they are the original "gas-and-go" engines, (so to speak) you can support a much higher flight rate initially.

But it does. An LV that has only rocket engines is simpler than LV that has rocket and airbreathing jet engines. There maybe only few moving parts in jet engines but that does not denote simplicity. It does not matter if the jet stage would support 100x the flightrate your rocket part can do, the lowest common flightrate is the flightrate of your system.

An orbital launch provider has to have the knowhow to do rocketry. If jet engines and ramjets are added to the system, then you have to either outsource or hire the need knowhow and manufacturing for those.

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Ramjets have a good T/W... Once they get going :) But they have to have a "boost" to get up to operations speed. The idea has been suggested to use integral solid boosters to get them up to speed, (and there are several examples of tested and operational engines employing this method) but again, you're looking at having to process the engines and reload them before they can be used again. Effecting your flight rate.

No reason why the initial booster couldn't be a simple pressure fed rocket. Even the same engines that are lit up again once ramjet has done it's job.

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The idea is to have a flight ability similar to a standard aircraft instead of what is usually thought of for a rocket vehicle.

What you mean by flight ability?
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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #102 on: 02/20/2013 08:54 pm »
One thing to keep in mind is that the point isn't "saving" propellant or really replacing some disposable SRBs for a few extra pounds to orbit. What you're doing is using highly reusable, high ISP engines for launch assist. (Jets measure their operation time in hours unlike rocket engines which are minutes at best)

As you wrote, it's a launch assist system. The whole system needs a rocket anyway. All you accomplish with jets is that your rocket stage can be less massive. Most mass saved is propellant. No reason why a rocket engine can't have cumulative operation time measured in hours. And they have demonstrated that. As far as reusability goes what does a pure jet stage offer that similar purely rocket powered couldn't do? Other than do it with less propellant.
What rocket engine has demonstrated operations times of "hours?" The high-time leader as far as I'm aware is the RL10 and it has a little over 10 minutes IF you can keep it in propellant. After that your risking tubopump or other mechanical failure.

While there is probably no fundemental reason you couldn't design and build a very robust, very high time rocket motor it probably won't be low cost, low weight or optimized and it certainly won't be anything "off-the-shelf" and available.

Yes, the idea is a "launch assist" and therefore is generally to get the rocket portion of the vehicle up to a speed and altittude where it works best. While this could save you "mass" of the vehicle including propellant, another possibly a better way to think of it is "additive" mass in that it can allow you to have mass dedicated on the vehicle to recovery and reusability hardware allowing it to be reusable instead of expendable.

As for what they would "add" compared to a pure rocket system let me first move this:
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The idea is to have a flight ability similar to a standard aircraft instead of what is usually thought of for a rocket vehicle.
What you mean by flight ability?
Jet engines have a "flight-ability" currently measured in hours of operation before a major inspection or overhaul. Rockets on the other hand have similar ability measured in minutes at most. A jet engine booster would have a turn around time dicated in minutes, thus allowing a higher re-use rate. Literally, "gas-and-go" operations. Flight operations would be constrained more by stacking/mating and check out of the rocket powered stages rather than the air-breathing stages allowing a higher fight rate to be possible.
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It doesn't "violate" KISS, you're using "simple" jet engines in their best range of use. (Keep it below Mach-3 and you normally can get away with simple inlets and exhausts and no major aerodynamics) And since they are the original "gas-and-go" engines, (so to speak) you can support a much higher flight rate initially.

But it does. An LV that has only rocket engines is simpler than LV that has rocket and airbreathing jet engines. There maybe only few moving parts in jet engines but that does not denote simplicity. It does not matter if the jet stage would support 100x the flightrate your rocket part can do, the lowest common flightrate is the flightrate of your system.
And a horse is of course much simpler to operate than a steam engine OR a rocket correct? KISS is a guidline, not a universal, must be followed rule and there are reasons and times when it can be bent or even ignored.

Yes an airbreathing LV is going to require designing and playing to each segments "strengths" and while a jet engine isn't as simple as a rocket engine in most cases, in most cases a jet has much higher reliability and operability than a rocket.
Indeed the limits of the system are going to be determined by the part with the lowest flight-rate/operability standards. But at the same time raising the operability/flight-rate standard is possible when you reduce the number of systems that limit that part of the equation. Up to a limit of course.
(You realize where this "logic" ends up right? You're going to end up arguing that rockets are the limiting factor, which they ARE but not THE limiting factor and not something that can't be changed with good design and construction. Just FYI :) )

Rockets are required by the overall system architecture, (orbital flight) so they must be included. Reducing them to the most basic "needed" system that can be easily and quickly maintained and operated would be an ideal way to allow a higher flight rate by the overall system. That takes mass though and currently the only way to "allow" robust reusability is to reduce something ELSES mass and this normally ends up being the payload.
Launch Assist usually ends up allowing you to have more "fiddle" room in your mass margins and jet-assist seems to be the most near-term, easily fielded type of launch assist.
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An orbital launch provider has to have the knowhow to do rocketry. If jet engines and ramjets are added to the system, then you have to either outsource or hire the need knowhow and manufacturing for those.
I'll point out that "orbital launch providers" in general have a LOT of "knowhow" in general and though they made need some 'help' in specific areas it's not quite as bad as you make out. For example Blue Origin didn't "outsource" or "contract" for the development and operation of the "Charon" VTVL test-bed vehicle:
http://www.museumofflight.org/aircraft/charon-test-vehicle

An "orbital launch provider" would simply operate the LV under the design and operations guidlines provided for the specific vehicle. This really isn't any different than what is done now. It's in your flight control and trajectory area that things would be different in that staging altitude and speeds would be different than a "normal" LV but optimized for the particular LV being used.

Specifically what we're talking about here is not the launch "provider" actually but the LV designers and construction which would necessitate specific details to accomodate the differences from "normal" LV. As originally envisioned the Jet Engine first stage was comparable to the GEM-Solid rockets used for launch assist being recoverable and reusable with minimum effort and cost. A different launch profile was required to gain the maximum benifit from the concept and in transitioning to a full-up "stage" the same would hold true here. The trajectory is more depressed and aero-loads are higher therefore the design and construction of the upper stage(s) would have to take this into account.
As keeps getting said here, "Rockets aren't Legos" so this isn't really a huge issue overall :)

For the most part the "knowhow" is out there to be had, that's not and never has been a "problem" area. What the 'problem' seems to be is mainly if you have a hammer, everything looks like a nail, even if it's a bolt...
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Ramjets have a good T/W... Once they get going :) But they have to have a "boost" to get up to operations speed. The idea has been suggested to use integral solid boosters to get them up to speed, (and there are several examples of tested and operational engines employing this method) but again, you're looking at having to process the engines and reload them before they can be used again. Effecting your flight rate.
No reason why the initial booster couldn't be a simple pressure fed rocket. Even the same engines that are lit up again once ramjet has done it's job.
Actually why "light-them-up" twice? Fire them once then throttle back as far as you can and let the ramjets do the work in the area they are good at. (Of course "simple-pressure-fed" and "throttling" don't very often go together and when they do "cheap" is pretty much out the window...)

The "standard" counter to the idea of using your main rocket engine(s) to boost your ramjets of course is; "If you're going to light them up for take off why bother with flying the trajectory needed for efficent ramjet operation at all?" In my mind the main idea of using air-breathing is to save the rockets for when they are "best" to use which includes using turbojet/fan engines to get up to ramjet speed since the vehicle would have to be designed and constructed to be able to handle an air-breathing trajectory anyway. The higher operability and maintenance of turbojet/fans engines would be a factor in their favor.

Ramjets are good for (as I understand it) normally about double mach numbers. In other words if it "starts at Mach-2 it will run "well" till about Mach-4, even if its not "nominal" all allong that range. (A good example being the ASALM ramjet missile which had a fixed inlet designed for nominal operation at Mach-3 managed to make it almost to Mach-6 while still accellerating during a test: http://www.designation-systems.net/dusrm/app4/asalm.html )

In either case, (ramjets or air-breathing in general) the upper stage would have to be designed to help entrain and direct the airflow to offer the best performance as well as withstand the heating and aeroloads.

NASA-Dryden, (admittedly more "jet-people" normally than "rocket-people") seem to think that using jet engines to boost the ramjet stage to speed has operations and maintenance points in its favor since they choose them for their concept. From what I've read I would tend to agree with them, especially from those measuring points. (Not sure I agree at all with the idea of using parachutes and landing the jets on a barge and the ramjet in the sea though.)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Asteroza

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Re: Jet Powered First Stage
« Reply #103 on: 02/20/2013 11:57 pm »
Wouldn't a turbine/ejector ramjet combo lining a ring booster improves operations though, since a single integrated jet booster would retain landing and self ferry capability while taking advantage of ramjets ops? Easy to see conventional jets in the ring "spokes" next to ramjet channels operating as the ejector, maybe use that GTX trick of thermal throating and upstream fuel injection to shorten the ramjet channel?

Though ops depends on the extent of the ramjet boost duration, pointing out whether this is effectively a zoom climb or if there's a substantial down range/ launch velocity component.

Offline R7

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Re: Jet Powered First Stage
« Reply #104 on: 02/21/2013 09:29 am »
What rocket engine has demonstrated operations times of "hours?" ..
While there is probably no fundemental reason you couldn't design and build a very robust, very high time rocket motor it probably won't be low cost, low weight or optimized and it certainly won't be anything "off-the-shelf" and available.

IIRC RL-10 test items have had cumulative runtime measured in hours. Somewhat surprisingly even RS-68 has amassed >1hr tests:

http://www.pw.utc.com/Press/Story/20120629-1200/2012/All%20Categories

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During hot-fire tests, the RS-68A engine demonstrated the ability to operate for 4,800 seconds of cumulative run time – more than 10 times what’s needed to boost the Delta IV Heavy rocket into space.

I recon it was either without the ablative nozzle part, or it was changed between firings or special beefed up ablative nozzle was used. And that by an engine designed to be expendable from day one. AFAIK RL-10 could run pretty much indefinitely as long as there's propellant and lubricant for the gearbox. Pressurefed systems would have even less parts that limit max runtime.

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Jet engines have a "flight-ability" currently measured in hours of operation before a major inspection or overhaul. Rockets on the other hand have similar ability measured in minutes at most. A jet engine booster would have a turn around time dicated in minutes, thus allowing a higher re-use rate. Literally, "gas-and-go" operations. Flight operations would be constrained more by stacking/mating and check out of the rocket powered stages rather than the air-breathing stages allowing a higher fight rate to be possible.

There is no fundamental reason why rocket powered "assist" stage could not function in the same manner. The fact that engines like RS-25/RD-171 and BIMs/NK-33 purge seals etc. require a lot of time to turn around does not mean that all rocket engines will. DC-X / newSpace have demonstrated quick operations. If you want a rocket engine with little maintenance you don't design it to push the envelope like RS-25 did. It had to because the overall system required it. Rocket powered launch assist would have much more relaxed requirements. Should also be remembered that the powered assist flight time similar to jet stage would be about a minute.

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And a horse is of course much simpler to operate than a steam engine OR a rocket correct? KISS is a guidline, not a universal, must be followed rule and there are reasons and times when it can be bent or even ignored.

KISS is a philosophy to aim for simplest solution for given task. If the task is to round up cattle in cross country a horse is best from your list. If the task is to turn aircraft carrier's propeller then steam engine(turbine) is better than a horse or a rocket. If you want to fly into outer space horse and steam engine fail  ;)

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(You realize where this "logic" ends up right? You're going to end up arguing that rockets are the limiting factor, which they ARE but not THE limiting factor and not something that can't be changed with good design and construction. Just FYI :) )

Exactly ;D and when rocket can be designed to allow higher flight rates for upper stages, what's stopping doing the same for rocket powered first/assist stage?

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jet-assist seems to be the most near-term, easily fielded type of launch assist.

This is where I just respectfully disagree :) LV manufacturer who already does rocket engines can field a rocket engine with more ease.

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I'll point out that "orbital launch providers" in general have a LOT of "knowhow" in general and though they made need some 'help' in specific areas it's not quite as bad as you make out. For example Blue Origin didn't "outsource" or "contract" for the development and operation of the "Charon" VTVL test-bed vehicle:
http://www.museumofflight.org/aircraft/charon-test-vehicle

A derelict early jet engine from the 50s to power subsonic hops on a testbed? Even Bezos discarded the idea, that's in a museum now, right? There's quite a leap from that to say ring of P&W F135s. Those don't come cheap nor the required training for maintenance.

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As keeps getting said here, "Rockets aren't Legos" so this isn't really a huge issue overall :)

For the most part the "knowhow" is out there to be had, that's not and never has been a "problem" area. What the 'problem' seems to be is mainly if you have a hammer, everything looks like a nail, even if it's a bolt...

Everything is Legos if the builder is adept enough. The jet assist concept treats jet engines as Legos to aid rocketry. Only problem in getting the knowhow is that it costs extra. Can not assume every rocket engineer to be jet engineer too. IMHO spaceflight's problem is that excessively technical solutions are proposed to 'improve' hammering of nail with a hammer  ;)

Technical curiosity: would existing high performance jet engines mind if run vertically most of the time, no lubrication issues etc?

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Actually why "light-them-up" twice? Fire them once then throttle back as far as you can and let the ramjets do the work in the area they are good at. (Of course "simple-pressure-fed" and "throttling" don't very often go together and when they do "cheap" is pretty much out the window...)

Was only an example. Throttling down would be another possibility. Nothing special about throttling a pressure fed engine, control ullage pressure/adjust valves. Blow-down system inherently throttles down. The first stage might be pump-fed too if the design calls for it to continue flight long after ramjets are done.

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The "standard" counter to the idea of using your main rocket engine(s) to boost your ramjets of course is; "If you're going to light them up for take off why bother with flying the trajectory needed for efficent ramjet operation at all?"


Keep it simple, don't attempt fly any special ramjet trajectory.

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Ramjets are good for (as I understand it) normally about double mach numbers. In other words if it "starts at Mach-2 it will run "well" till about Mach-4, even if its not "nominal" all allong that range. (A good example being the ASALM ramjet missile which had a fixed inlet designed for nominal operation at Mach-3 managed to make it almost to Mach-6 while still accellerating during a test: http://www.designation-systems.net/dusrm/app4/asalm.html )

Yes, AFAIK their efficiency peaks at about mach 3. But they can be operated even from subsonic speeds. If initial boost given by rocket then lit up the ramjet as soon as it's Isp is above rocket engines. MIPCC extends the upper regime. Is mlorrey still active here? He knew ramjet-stuff well. Or did he fly away with the orbital F-106 he was designing.

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NASA-Dryden, (admittedly more "jet-people" normally than "rocket-people") seem to think that using jet engines to boost the ramjet stage to speed has operations and maintenance points in its favor since they choose them for their concept. From what I've read I would tend to agree with them, especially from those measuring points. (Not sure I agree at all with the idea of using parachutes and landing the jets on a barge and the ramjet in the sea though.)

Their hammer is the jet engine  ;)

A summary, (IMOs):
1. Jet stage does not improve LV flight rate unless rocket stages improve their flight rates too.
2. If rocket stages manage to do that then purely rocket powered LV could have improved flight rate too.
3. From 1&2 follows that jet stage net effect is fuel saving at the cost of extra complexity.

YMMV

PS note that I don't think there's anything technologically infeasible with jet/ramjet assist. Just questioning it's ability to dramatically improve flight rates and economy.
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Offline watermod

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Re: Jet Powered First Stage
« Reply #105 on: 02/21/2013 05:29 pm »
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PS note that I don't think there's anything technologically infeasible with jet/ramjet assist. Just questioning it's ability to dramatically improve flight rates and economy.
Speaking to the economy question:
From some of the jet engine proposals that were out there -- my impression was that it was desired to use engines from "bone-yard" fighters or near end-of-life engines.   Sort of semi-disposable and near free.  Then "economy" would be somewhat dependent on the average state of engines from the bone-yard or those near EOL ones pulled for replacement.


 

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #106 on: 02/22/2013 03:15 pm »
Going to break this up into sections if y'all don't mind :)

Rocket engines:
IIRC RL-10 test items have had cumulative runtime measured in hours. Somewhat surprisingly even RS-68 has amassed >1hr tests:

http://www.pw.utc.com/Press/Story/20120629-1200/2012/All%20Categories

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During hot-fire tests, the RS-68A engine demonstrated the ability to operate for 4,800 seconds of cumulative run time – more than 10 times what’s needed to boost the Delta IV Heavy rocket into space.

I recon it was either without the ablative nozzle part, or it was changed between firings or special beefed up ablative nozzle was used. And that by an engine designed to be expendable from day one. AFAIK RL-10 could run pretty much indefinitely as long as there's propellant and lubricant for the gearbox. Pressurefed systems would have even less parts that limit max runtime.
Ok, here's where you have to be REALLY careful what we are talking about :)

I went back and re-read your original post which read:
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No reason why a rocket engine can't have cumulative operation time measured in hours. And they have demonstrated that.
I see now that I MISSED a mistake on your part. "I" was discussing OPERATING time, and there is a HUGE difference between that and "CUMULATIVE" opertating time that I should have addressed.

OPERATING time is the time which an engine can "run" under normal conditions between major maintenance and overhauls.

CUMULATIVE operating time is the TOTAL time an engine has run under all conditions EXCLUDING and not considering major maintenance and overhauls.

I'd mentioned the RL10 which P&W specifically states CAN operate for up to 600 seconds with multiple re-starts. This is actually "cumulative" operations time with no maintenance or repairs and they will not and do not suggest or infer that it will actually operate for ONE SECOND after that time! This is even though they have a bench test engine that has a 'cumulative' opertions time of several THOUSAND hours. Why? Because the "cumulative" operations time of the test bench engine does not include that the engine itself has been re-built several dozen times and numerous parts have been replaced in between of those times of "operation" during the years.

The RS-68A engine that "accumulated" over 4,800 seconds of "operation" did so during multiple 10-minute fireings with major overhaul, (including at least one turbopump replacement IIRC) and replacement of "expended" parts (including the ablative liners) between each fireing. The total test took place over a two-week period, with the engine being removed from the test stand and brought back to the shop between each test, then returned and re-installed on the stand.
(And it accurate at this point to "note" that the press release is incorrect, 4,800-seconds is only 80-minutes. That is EIGHT flights to orbit not the "over-10" times they state. Just FYI :) )

Meanwhile I would point out that "cumulative operations" time on jet engine test articles is measured in YEARS and the majority of jet engines measure mean-time between major maintenance and servicing in THOUSANDS of hours, minimum.

Rocket engines HAVE gotten better, and they could be designed and built even more robust, but as I noted that won't be cheap, light, or optimized.

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There is no fundamental reason why rocket powered "assist" stage could not function in the same manner. The fact that engines like RS-25/RD-171 and BIMs/NK-33 purge seals etc. require a lot of time to turn around does not mean that all rocket engines will. DC-X / newSpace have demonstrated quick operations. If you want a rocket engine with little maintenance you don't design it to push the envelope like RS-25 did. It had to because the overall system required it. Rocket powered launch assist would have much more relaxed requirements. Should also be remembered that the powered assist flight time similar to jet stage would be about a minute.
The DC-X actually did NOT actually demonstrate "quick" operations, per-se, having an average turn-around of sevreal hours at best and usually several days. It also didn't fly enough to accumulat enough flight time to require major engine maintenance. The engines were never "turned-around" during testing as they would have to be for a full run flight. Had the program continued for enough time to get to swapping out the engines on a regular basis, (which was how the engines were "maintained" being removed and shipped back to the factory for rebuilding) the design of the DC-X was such that such engine swaps would be fairly "simple" compared to anything previously. That's still not saying all that much really though because "previously" no vehicles had been designed for swapping the rockets on a regular basis. (The closest example was the X-15 and it required some major effort to remove and replace the motors)

Your correct that the total powered flight envelope of the Jet (or rocket) assist stage would be around a "minute" (with boost-back and landing it would probably be closer to two-minutes overall) assuming of course that a similar rocket stage was used ONLY for that amount of time and portion of the trajectory.
(The "argument" would be of course that while that is "good" for the jet stage a rocket powered stage would be "better" utilized in a different manner of course :) )

Assuming the "1-minute" figure for a moment though you realize that works out to 1/60th of the TOTAL operations time of an RL10 engine? At best you've now got only 59 flights left before you MUST perform extensive maintenance on the engine. (Probably closer to about 30 flights actually, being conservative) Meanwhile that "minute" on the jet has only contributed 1-minute towards a total time of 1000 HOURS before major maintenance? Even assuming for some reason that you cut the number of hours by a factor of 10 to 100 HOURS the jet stage has accumulated almost no significant time towards major maintenace as compared to the rocket.

"1-minute" of operation for a rocket engine and a jet engine are very, very different things and despite "relaxed" standards the jet still is much easier and simpler to (as well as cheaper) to maintain than the rocket.
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Exactly  and when rocket can be designed to allow higher flight rates for upper stages, what's stopping doing the same for rocket powered first/assist stage?
Because the rocket is in fact a "limiting" factor but it is not THE limiting factor and tends to become LESS of an issue as its role decreases :)

We've already run into this issue in that "expendable" vehicles are more economical and easier to develop. Following the "logic" of course (which NASA-Dryden did in their design) then using an "expendable" upper stage increase you flight rate greatly as long as your using reusable (non-rocket) LOWER stages.

IMHO though is that a reusable upper stage would end up being more cost effective even though it's using a rocket IF you design it right to keep the rocket from being "the" limiting factor. The DC-XA was on it's way to demonstrating a proper designed re-usable vehicle with maintenance and replacement designed into it in order to make swapping engines much less of an issue.

You'd still be "limited" by having to swap out your rocket engines after every flight, (or "accumulated" operations time of less than 10 minutes) but that becomes part of your flow-process rather than you're limiting flight rate factor. (Especially if you have more than one upper stage available)
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This is where I just respectfully disagree :) LV manufacturer who already does rocket engines can field a rocket engine with more ease.
Respectfully, it would really depend... Using SpaceX as an example as long as the engine was a dirivitive of an already existing engine you MIGHT be right. But a new design/build or highly derivitive engine wouldn't be.

And a LOT of that is overall company/design philosophy as well. SpaceX (Musk specifically) does not "feel" that either air-breathing or "flying" of any sort is a part of their program and have specifically gone away from any uses of those technologies in their operations and design. They have specifcially ruled out any sort of "launch-assist" for any of their vehicles as well.

Their decision but its been shown that pretty much ANY number of simple LA ideas would have significantly increased both the payload and probably the operability of the Falcon-1.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #107 on: 02/22/2013 03:26 pm »
Speaking of KISS as a philosophy and principle:
KISS is a philosophy to aim for simplest solution for given task. If the task is to round up cattle in cross country a horse is best from your list. If the task is to turn aircraft carrier's propeller then steam engine(turbine) is better than a horse or a rocket. If you want to fly into outer space horse and steam engine fail  ;)
KISS involves much more than "just" applying the simiplest solutioni to a given task. It involves also making sure that you have looked at ALL possible solutions even if they would seem to be in violation of the overall philosophy at first. Often, when all other factors are taken into account KISS has to give way to other factors.

Economics comes into play as well as maintenance and overall operability and those don't necessarily turn to the "simplest" system to get the whole job done. Yes it has a lot to do with it but just because a rocket engine is "simpler" than a jet engine does not transfer to its economy, maintainability or usefullness when considering the whole launch picture.

Of course as per usual, each and every example can have other issues involved and considerations that must be taken into account so it really DOES end up being mostly a situation of YMMV and a lot of times it is ones indivicual assumptions and "leanings" that end up being the most important factors involving what falls into or does not as the case may be, KISS :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #108 on: 02/22/2013 04:52 pm »
Jets and Ramjets
I'll point out that "orbital launch providers" in general have a LOT of "knowhow" in general and though they made need some 'help' in specific areas it's not quite as bad as you make out. For example Blue Origin didn't "outsource" or "contract" for the development and operation of the "Charon" VTVL test-bed vehicle:
http://www.museumofflight.org/aircraft/charon-test-vehicle

A derelict early jet engine from the 50s to power subsonic hops on a testbed? Even Bezos discarded the idea, that's in a museum now, right? There's quite a leap from that to say ring of P&W F135s. Those don't come cheap nor the required training for maintenance.
Blue Origins didn't "discard" as much as they finished the test program they planned on. Yes it's in a museum and yes it used commercially bought and maintained jet engines to test a concept. No it's not really that much of a "leap" from there to using modern fighter engines in the same role to a higher degree. The basic principle is pretty much the same overall.

I've no idea how much Bezo's paid for the engines, the original concept quoted to Boing directly from P&W was that the F100-229s would be high-time, surplus engines (less than 1000-hours left on them) with all modifications needed done before delivery at a price of $2-million per engine. Rocketdyne at the same time quoted about $4-million per RL10 with 6 engines per "vehicle" and the engines being swapped out and returned to them for over-haul after each fight. The RL10s were "certified" for a total of 40 flights, (cumulative overall opertions time of about 40 minutes) before they would be retired and new ones required. The jet engines on the other hand were "certified" for more time than the overall flight program was designated before major maintenance even though they were surplus and high time. (200 "flights" planned for the program for refrences purposes)
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As keeps getting said here, "Rockets aren't Legos" so this isn't really a huge issue overall :)

For the most part the "knowhow" is out there to be had, that's not and never has been a "problem" area. What the 'problem' seems to be is mainly if you have a hammer, everything looks like a nail, even if it's a bolt...

Everything is Legos if the builder is adept enough. The jet assist concept treats jet engines as Legos to aid rocketry. Only problem in getting the knowhow is that it costs extra. Can not assume every rocket engineer to be jet engineer too. IMHO spaceflight's problem is that excessively technical solutions are proposed to 'improve' hammering of nail with a hammer  ;)
Jet assist doesn't treat jet engines as Lego's at all. Instead it treats them as a unit in part of a system. Much the same way a first and second stage are treated both as a unit and also part of a system.

You are correct that you can't "assume" a rocket engineer is a jet engineer and vice-versa. You CAN however treat knowhow and knowledge as "Lego" parts to be plugged into the equations where necessary. The 'cost' of the knowhow is and will always be rather subjective because you CAN have it for free if you really want to work at it. In most cases it's often "cheaper" though to find someone with that knowhow/knowledge and simply pay them for their time and effort.

While I respect and somewhat share your opinion on the "problem" with spaceflight in general, my opinion and what I've seen trend more towards the issue being people continuing to try and improve the hammer when what they really needed in the first place was a wrench...
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Technical curiosity: would existing high performance jet engines mind if run vertically most of the time, no lubrication issues etc?
Jet engines in general and military engines specifically are designed to have no issues what-so-ever running in ANY orientation. That said however part of the "modifications" that P&W were talking about were to allow them to START while vertical and to maintain a pressurized system during the entire flight regime.
(While a jet will RUN in any position they are not generally designed to START in any position. However this isn't really a major issue and was expected to be a very easy and cheap "mod" to do. This goes for the Rolls-Royce Vipers in the "Charon" vehicle as well. They had to have mods to allow them to start vertically but once running they were fine)
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Actually why "light-them-up" twice? Fire them once then throttle back as far as you can and let the ramjets do the work in the area they are good at. (Of course "simple-pressure-fed" and "throttling" don't very often go together and when they do "cheap" is pretty much out the window...)

Was only an example. Throttling down would be another possibility. Nothing special about throttling a pressure fed engine, control ullage pressure/adjust valves. Blow-down system inherently throttles down. The first stage might be pump-fed too if the design calls for it to continue flight long after ramjets are done.
Understood but a blow-down system that can then throttle back UP is NOT so simple. Look at the LM pressure-fed, throttlable system.
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The "standard" counter to the idea of using your main rocket engine(s) to boost your ramjets of course is; "If you're going to light them up for take off why bother with flying the trajectory needed for efficent ramjet operation at all?"


Keep it simple, don't attempt fly any special ramjet trajectory.
Then you don't use a ramjet at all. It won't do you any "good" that way. No time to ramp up thrust and no time for the ISP modification to kick in. The normal "rocket" trajectory is not going to allow any time for a ramjet to work.

At best you could use a RENE, (Rocket Engine Nozzle Ejector) system to increase thrust/ISP from start to about Mach-1 but then you'd have to drop the extra mass to allow the rocket to operate on it's own.
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Ramjets are good for (as I understand it) normally about double mach numbers. In other words if it "starts at Mach-2 it will run "well" till about Mach-4, even if its not "nominal" all allong that range. (A good example being the ASALM ramjet missile which had a fixed inlet designed for nominal operation at Mach-3 managed to make it almost to Mach-6 while still accellerating during a test: http://www.designation-systems.net/dusrm/app4/asalm.html )

Yes, AFAIK their efficiency peaks at about mach 3. But they can be operated even from subsonic speeds. If initial boost given by rocket then lit up the ramjet as soon as it's Isp is above rocket engines. MIPCC extends the upper regime. Is mlorrey still active here? He knew ramjet-stuff well. Or did he fly away with the orbital F-106 he was designing.
Actually a ramjet CAN operate up to around Mach-8 NORMALLY and depending on how well it's designs it can actually operate up beyond Mach-10+ as long as the interior "subsonic" combustion drag doesn't exceed the thrust generated. (Glenn Olson did an indepth study of ramjet design and found that engineers were quite confident they could design a subsonic-combustion ramjet that could operate up to around Mach-12, however it would have a 'start' speed of around Mach-6 for begineers and after Mach-12 it would be extremely difficult to keep the interior airspeed from exceeding Mach-1. Marquardt engineers were quoted as saying they couldn't see any reason why the BOMARC ramjets couldn't operate up to Mach-10 except for the "little" fact that the airframe fell apart well before then : )

Fuel consumption is the biggest issue when ramjets operate "off-nominal" modes. They tend to be very, very inefficent at speeds below or above their "nominal" opertions modes. Now this of course changes if they have variable inlets and exhausts which allows them to vary the "nominial" operations speeds. For example a variable inlet and exhaust system on what would normally be a Mach-2 point design, (such as the fixed inlet ASALM above) would be able to operate much more near "nominal" at speeds around Mach-1 to above Mach-6 but at the cost of heavier and more complex inlet and exhaust mechanisms.

MLorry is still around I think though I haven't seen him post in quite a while. MIPCC (Mass Injection Pre-Compression/Compressor-Cooling for those who don't know :) ) is useful to both extend the range of and increase the thrust of, (at a cost of ISP because you're exepending more "propellant") any airbreathing system. It can effectivly double the normal Mach range of a turbojet/fan engine as well as doubling the output thrust. If you use LOX in addition to simply water, (as the RASCAL concept proposed) you can also increase the high altittude performance of an airbreathing engine as well as keep combustion chamber stability over a higher performance range. (Again that's an ISP hit due to another "consumable" though)
I'd suggested using it to boost the take off thrust of a jet-engine first stage
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NASA-Dryden, (admittedly more "jet-people" normally than "rocket-people") seem to think that using jet engines to boost the ramjet stage to speed has operations and maintenance points in its favor since they choose them for their concept. From what I've read I would tend to agree with them, especially from those measuring points. (Not sure I agree at all with the idea of using parachutes and landing the jets on a barge and the ramjet in the sea though.)

Their hammer is the jet engine  ;)
Well that's kind of a "given" since they are more "aero" than "space" orientated but they have a point in that using two highly reusable, high usage, stages and limiting your low-use, low operations stage to a single, expendable stage would have advantages.

I'm not sure it's actually that jets are thier "hammer" though as much as they are looking at the question and saying, "If we only NEED a hammer for the last part of the fight, what's wrong with using a wrench for the first two parts?"

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #109 on: 02/22/2013 05:15 pm »
A summary, (IMOs):
1. Jet stage does not improve LV flight rate unless rocket stages improve their flight rates too.
2. If rocket stages manage to do that then purely rocket powered LV could have improved flight rate too.
3. From 1&2 follows that jet stage net effect is fuel saving at the cost of extra complexity.
1) Doesn't necessarily follow because it "depends" on if the rocket stage IS capable of an improved 'flight-rate' and specifically how that is accomplished.

If for example you use "cheap, expendable" rocket stages then your flight rate is production and processing limited.
However if you're using a reusable upper stage then your return, refurbishment and processing time now is your limiting factor.

In either case if you are able to keep any type of "back-stock" of orbital stages awaiting launch then your limiting factor is simply how fast you can stack, check-out, then launch the vehicle. The problem with doing this with JUST a rocket powered LV is that you are always going to run into the issue of the time it takes to return a rocket powered vehicle to launch-ready status.

2) The problem here is the premis of it being the same which I've already pointed out isn't the same at all. Even if rocket stages managed to actually have "operating" times in 10s of minutes they are still limited compared to air-breathing systems. The "issue" isn't so much a matter of "if they can as to "how" they can since the cabability already exists to IMPROVE flight rates EVEN useing current rocket stages. Howeve in order to make the "case" you can't have ALL rocket stages and get to the same position.

3) Since this follows the "conclusions" of the original 1&2 which are incorrect... :)

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YMMV
Usually by a lot :)

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PS note that I don't think there's anything technologically infeasible with jet/ramjet assist. Just questioning it's ability to dramatically improve flight rates and economy.
And that's of course always a GOOD thing :)

The ability to increase fight rates is pretty much going to end up always being based on the rocket portion of the LV design. The air-breathing parts are known and can easily be proven to be able to significantly increase flight rates. Less maintenance and less "turn-around" will also pretty much always lead to increased economy, we have enough evidence of this with flying transport of passengers and cargo. How much is a question that relates to design and usage.

Taking the NASA-Dryden example, (as an example) if you have only a single rocket stage based on the cost of a Centaur-III stage which is used once and expended, and based on a turn around time in days, how much payload can you get to orbit per flight and how many flights per week?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #110 on: 02/22/2013 05:31 pm »
Wouldn't a turbine/ejector ramjet combo lining a ring booster improves operations though, since a single integrated jet booster would retain landing and self ferry capability while taking advantage of ramjets ops? Easy to see conventional jets in the ring "spokes" next to ramjet channels operating as the ejector, maybe use that GTX trick of thermal throating and upstream fuel injection to shorten the ramjet channel?

Though ops depends on the extent of the ramjet boost duration, pointing out whether this is effectively a zoom climb or if there's a substantial down range/ launch velocity component.
It's a thought, but he general issue with combo-systems is getting everything to work at thier "best" point while still dragging along the systems that either are not operating at their best or have yet to operate.

The turbojet/fan boosters operate "best" from start (sea-level) to around Mach-2 (@40,000ft), on the other hand the ramjet portion operates best from Mach-2 (@40,000ft) to Mach-4 (@100,000ft, assuming a "fixed" inlet and exhaust system) and the rocket (with a vacuum optimized nozzle set) operates from there.
You can GET a turbojet/fan to operate above Mach-2 but it takes some "tricking" of the engine or extra-systems/materials/etc to get them to do so on a regular basis. The same can be said of a ramjet engine as I noted they CAN operate up to around Mach-10 given the right systems, materials and engineering. It just won't be "cheap, and easy" stuff to accomplish on a regular basis.

On top of all of this you have to sit down and design and build the rocket stage to HELP the airbreathing systems as well as do it's own job. This means being able to withstand a higher aeroload and heating than "normal" for a rocket trajectory as well as being designed to "feed" air into those engines at higher speed.

At some point if Jet Assist were to take off (pardon the pun but I really could NOT avoid that one :) ) it will probably make a lot of sense to design an intergrated turbofan/ramjet stage to do away with the two stage system. I'd see that as a design evolution eventuality. MY feeling at this point though is to just get the concept up and running and show it off rather than worrying about totally optimizing the system from the start :)

Good feedback though.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline R7

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Re: Jet Powered First Stage
« Reply #111 on: 02/22/2013 05:43 pm »
Going to break this up into sections if y'all don't mind :)
Yes these are getting a bit long  ;D Stupid message edit screen is ridiculously small for these...oh wait you can actually drag it bigger. Wohoo!

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I'd mentioned the RL10 which P&W specifically states CAN operate for up to 600 seconds with multiple re-starts. This is actually "cumulative" operations time with no maintenance or repairs and they will not and do not suggest or infer that it will actually operate for ONE SECOND after that time!
They burn in Centaurs over 900 seconds. At least according to AtlasV User Guide. Unlikely that they'd break the second after that, margin is left just like for RS-68.

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The RS-68A engine that "accumulated" over 4,800 seconds of "operation" did so during multiple 10-minute fireings with major overhaul, (including at least one turbopump replacement IIRC) and replacement of "expended" parts (including the ablative liners) between each fireing. The total test took place over a two-week period, with the engine being removed from the test stand and brought back to the shop between each test, then returned and re-installed on the stand.
Source for pump change? And of course they took the engine back to shop and dissected it between firings, it was being tested. The fact that it actually worked that long was nice to have bonus. Stock engine is rated for 'only' 1200 seconds / 8 restarts.



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the majority of jet engines measure mean-time between major maintenance and servicing in THOUSANDS of hours, minimum.
What about the jet engines proposed for jet assist? We are talking military engines, probably afterburner on, full throttle all the way due poor T/W. You may also need more of them than you'd need rocket engines.

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Rocket engines HAVE gotten better, and they could be designed and built even more robust, but as I noted that won't be cheap, light, or optimized.
With KISS you'd only need aim for the cheap from that list. Rocket engines have good T/W to begin with, wiggle room there. No need to diehard optimization like RS-25 if the aim is just to assist for the first minute.


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The DC-X actually did NOT actually demonstrate "quick" operations, per-se, having an average turn-around of sevreal hours at best and usually several days.  It also didn't fly enough to accumulat enough flight time to require major engine maintenance.
Several hours or even several days IS quick compared to today's flight rates. System that would fly even weekly would be a paramount change. It is unfortunate that it didn't proceed further, but the graveyard of promising concepts is large :(

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Assuming the "1-minute" figure for a moment though you realize that works out to 1/60th of the TOTAL operations time of an RL10 engine? At best you've now got only 59 flights left before you MUST perform extensive maintenance on the engine. (Probably closer to about 30 flights actually, being conservative) Meanwhile that "minute" on the jet has only contributed 1-minute towards a total time of 1000 HOURS before major maintenance? Even assuming for some reason that you cut the number of hours by a factor of 10 to 100 HOURS the jet stage has accumulated almost no significant time towards major maintenace as compared to the rocket.
And again, given current flight rates, if purely rocket powered assist system which actually does 30 annual flights would require one(1) major overhaul that's hardly a showstopper. Yes, technically jet stage wouldn't probably require maintenance at all in years but in practice I presume you would have to, due time alone and for harsh usage / unconventional orientation. Tried to look for maintenance plans for fighter jet engines, no luck. Do you have any references?

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Because the rocket is in fact a "limiting" factor but it is not THE limiting factor and tends to become LESS of an issue as its role decreases :)
Huh, it would still have to do most of the dv into orbit. And you'd still have all the payload integration issues etc. If you can't get rockets as quickly ready for the pad as the jet stage then rocket is the liming factor.

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Their decision but its been shown that pretty much ANY number of simple LA ideas would have significantly increased both the payload and probably the operability of the Falcon-1.

Interesting, links? Solids maybe but given Falcon-1's small payload a jet thing seems overly expensive to develop.
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Offline Danderman

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Re: Jet Powered First Stage
« Reply #112 on: 02/22/2013 05:52 pm »
Take a simple single stage suborbital launcher, like the first stage of a Falcon 1.

Weld a jet engine onto it, with a pod to contain a few hundred pounds of fuel. Assume the engine is carried by the rocket all the way to MECO.

Calculate the performance of the biamese system compared with the rocket by itself.

If performance improves, calculate the additional payload against the cost of the jet engine, pod, fuel, and additional ops cost.

Simple.
« Last Edit: 02/22/2013 05:53 pm by Danderman »

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #113 on: 02/22/2013 06:03 pm »
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PS note that I don't think there's anything technologically infeasible with jet/ramjet assist. Just questioning it's ability to dramatically improve flight rates and economy.
Speaking to the economy question:
From some of the jet engine proposals that were out there -- my impression was that it was desired to use engines from "bone-yard" fighters or near end-of-life engines.   Sort of semi-disposable and near free.  Then "economy" would be somewhat dependent on the average state of engines from the bone-yard or those near EOL ones pulled for replacement.
The issue is that even "bone-yard" engines are still pretty "usable" compartivly. A jet fighter engine is considered "high-time/surplus" normally when it has less than 1000 hours of "operation" time left on its frame. These are STILL pretty expensive pieces of equipment, a quick search shows that the J85 (from the T-38/F-5) jet engines are going (used) for $4500 if you can find them. More modern engines are harder to get both because of price and because of government control.
There are no F135 engines for sale because they are all "slotted" for aircraft under construction. You practically can't "buy" a legal F110 engine because of US import restrictions against Iran. (The government is afraid anyone who buys one is planning on selling it to them so they simply won't allow them to be sold) Meanwhile there are hundreds of early model P&W F100s in storage, and you could probably get some for reasonable price provided the Air Force will actually let them go, (since they still are used in many AF and AF-reserve aircraft) which is probably going to be the "best" possible engine for a while.

The original cost quote for a "high-time/surplus" F100-229 was $2-million dollars with all the needed modifications for launch assist. That was directly from Pratt-&-Whitteny based on their data and practices. As of today, (and with the web-searches I've managed to-date) that's about the ONLY data-point I have to go on.
P&W won't "quote" anyone off the street a price for an used-engine and will of course be HAPPY to sell you a brand new one instead :)
The same with GE and just about everyone else. Anyone that sell "used" engines doesn't usually sell "in-bulk" so the price quoted is PER engine and then they still might not actually HAVE an engine to sell you :)
(This seems especially true of high-powered engines)

The original concept used 10 engines to lift a "core" vehicle or around 95,000lbs, with a "purchase" of about 40 or so engines including spares and parts support. (30-poded engines, 10 spares plus parts, in the more "current" case that would be 3-boost ring vehicles, 10 spare engine sets and misc. parts support)

Price point would vary greatly under the present circumstances since the F100 is no longer considered a "front-line" engine in most cases and those in storage would be less likely to be pulled for line replacment units but might be considered strategic parts spares. Accepting for the sake of argument the original quoted price of $2-million per engine would probably be a good start at least. (I highly suspect it would probably be less given current circumstances but would rather ere towards conservative estimates)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #114 on: 02/22/2013 06:30 pm »
Going to break this up into sections if y'all don't mind :)
Yes these are getting a bit long  ;D Stupid message edit screen is ridiculously small for these...oh wait you can actually drag it bigger. Wohoo!
No! No! Don't tell me that I don't NEED the encouragment! :)
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Their decision but its been shown that pretty much ANY number of simple LA ideas would have significantly increased both the payload and probably the operability of the Falcon-1.

Interesting, links? Solids maybe but given Falcon-1's small payload a jet thing seems overly expensive to develop.
Elon's said he won't ever use solids but I can't seem to find the one I was originally thinking of, which wasn't air-breathing but simply a steam-rocket catapult :)
The Air Force showed up to a 60% delta-V improvement (improvment in payload) for a simple air-launch.:
http://www.darpa.mil/WorkArea/DownloadAsset.aspx?id=2147485147

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline R7

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Re: Jet Powered First Stage
« Reply #115 on: 02/22/2013 06:55 pm »
The Air Force showed up to a 60% delta-V improvement (improvment in payload) for a simple air-launch.:
http://www.darpa.mil/WorkArea/DownloadAsset.aspx?id=2147485147

F-1e with a wing, tailplane and rudder ... that's a complete structural redesign, the loads would be wildly different from what ordinary F-1e tanks could handle. StratoLaunch redux, so much for 'simple'  ;D
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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #116 on: 02/22/2013 07:05 pm »
The Air Force showed up to a 60% delta-V improvement (improvment in payload) for a simple air-launch.:
http://www.darpa.mil/WorkArea/DownloadAsset.aspx?id=2147485147

F-1e with a wing, tailplane and rudder ... that's a complete structural redesign, the loads would be wildly different from what ordinary F-1e tanks could handle. StratoLaunch redux, so much for 'simple'  ;D
"Some" redesign/rebuild was a given remember that the Falcon-1 CAN'T use any type "launch-assist" as is because of the way its made. The basic premis of the study was a complete re-design/rebuild of the F1 using pretty much the engine as the only original part :)

Before you dismiss the "wing/tailplane" (just like the Pegasus) you might consider that performance enhanment is in SPITE of the extra mass :)

"Better" would have been launched from below the Aircraft with a T/LADS which eliminates the need for the "wing/tailplane" entirely, but DARPA seems pretty much "stuck" in their perception of how "air-launch" has to be done...

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline R7

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Re: Jet Powered First Stage
« Reply #117 on: 02/22/2013 07:13 pm »
Before you dismiss the "wing/tailplane" (just like the Pegasus) you might consider that performance enhanment is in SPITE of the extra mass :)

I don't have anything against wings/tailplanes, but doubt that a vehicle that would actually work like that would have very little to do with original F-1e. Bit dubious that exhaustive redesign was actually done. Same problem as with F-5/StratoLaunch. Ordinary liquid rockets are pretty flimsy sacks of propellant. It's marketed as great achievement if they manage to just stand up on their own on the pad without internal pressure! ;) Now take that, flip horizontally and attach from the top to a carrier plane, or attach a wing on top of it. It's going to buckle without some serious reinforcement. But this is getting OT, gonna go watch Survivor now, need a breather from this thread  ;D
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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #118 on: 02/22/2013 07:39 pm »
I'd mentioned the RL10 which P&W specifically states CAN operate for up to 600 seconds with multiple re-starts. This is actually "cumulative" operations time with no maintenance or repairs and they will not and do not suggest or infer that it will actually operate for ONE SECOND after that time!
They burn in Centaurs over 900 seconds. At least according to AtlasV User Guide. Unlikely that they'd break the second after that, margin is left just like for RS-68.
I'm still finding only 600, but I can't get the guilde to pull up at the moment. 1000-seconds sounds about right for the most modern version though. I wouldn't actually be surprised if they got it up to half an hour eventually.
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The RS-68A engine that "accumulated" over 4,800 seconds of "operation" did so during multiple 10-minute fireings with major overhaul, (including at least one turbopump replacement IIRC) and replacement of "expended" parts (including the ablative liners) between each fireing. The total test took place over a two-week period, with the engine being removed from the test stand and brought back to the shop between each test, then returned and re-installed on the stand.
Source for pump change? And of course they took the engine back to shop and dissected it between firings, it was being tested. The fact that it actually worked that long was nice to have bonus. Stock engine is rated for 'only' 1200 seconds / 8 restarts.
Pump changed was mentioned in a paper on the testing cycle for the RS-68A mentioning they had "blisk" (disk/blade) issues during the first couple of test firings that required a pump replacement. And I understand it was a "test" program and they re-built it after each firing, (though they also state in one paper that they did much LESS rebuilding and firing than previous engine test programs before they certified the engine) and while it's good, 1200 seconds is still far, far less than what a jet engine is capable of.
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The DC-X actually did NOT actually demonstrate "quick" operations, per-se, having an average turn-around of sevreal hours at best and usually several days.  It also didn't fly enough to accumulat enough flight time to require major engine maintenance.
Several hours or even several days IS quick compared to today's flight rates. System that would fly even weekly would be a paramount change. It is unfortunate that it didn't proceed further, but the graveyard of promising concepts is large :(
Very true that last :(

However while days or even hours is "quick" compared to todays rocket flight rates I'll point out it's terrible compared to any aircraft flight rate. Again the closer you can get to THAT flight rate the better your economics gets.
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Because the rocket is in fact a "limiting" factor but it is not THE limiting factor and tends to become LESS of an issue as its role decreases :)
Huh, it would still have to do most of the dv into orbit. And you'd still have all the payload integration issues etc. If you can't get rockets as quickly ready for the pad as the jet stage then rocket is the liming factor.
Again it greatly depends on HOW the rocket ends up being the "limiting factor" in the process. If you have only a single rocket stage and you have to wait until it reaches the end of the complete turn-around phase then of course it becomes the most limiting factor in your process. If you have two rocket stages and one is ready to go as soon as your jet-stages are turned around it is less of a limitation. However the same is NOT true of multiple rocket stages because there is no way they can be processed that fast.

You actually run into the same 'issue' with multiple rocket stage concepts in that if your first stage is ready to fly within a few days but your upper stage is only ready to fly after a month then the upper stage becomes the processing stoppage point.

How do you get around that in a multiple-stage rocket? You build more upper stages or you simply accept that your flight rate will never be higher.

Sure the BIGGEST issue is and will continue to be who ever could THINK of enough missions/payloads to ever need more than (say) 30 launchers per year. (Your example, which comes to @2.5 launches a month, say off hand about two every two weeks)

But at the present moment even THAT amount of launchers is pretty far-fetched. Yet the turn-around time and operability of modern jet engines would fully support a flight rate GREATER than that. In order to actually do that you'd probably have to have at least 5 or so rocket stages, (30 if they were expendable) to allow you to meet that kind of schedule.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #119 on: 02/22/2013 07:46 pm »
the majority of jet engines measure mean-time between major maintenance and servicing in THOUSANDS of hours, minimum.
What about the jet engines proposed for jet assist? We are talking military engines, probably afterburner on, full throttle all the way due poor T/W. You may also need more of them than you'd need rocket engines.
The jet engines proposed for the concept are high performance military afterburning turbofan engines. Technically they do this all the time but specifically they are going to be operated at full military (afterburner) power for around 60 seconds and there after for a little under a minute on much lower power. This isn't really "unusual" operations for them they are both designed and built to operate under these conditions. Attention will have to be paid to the afterburner materials used to avoid problems but military engines are MADE to handle the heat and stress.

Due to the T/W you have to have more jet engines than rockets but again you're looking at a rocket that operates for 60 seconds (plus landing) has used up a significant amount of its total operating time. A jet engine has not.
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Assuming the "1-minute" figure for a moment though you realize that works out to 1/60th of the TOTAL operations time of an RL10 engine? At best you've now got only 59 flights left before you MUST perform extensive maintenance on the engine. (Probably closer to about 30 flights actually, being conservative) Meanwhile that "minute" on the jet has only contributed 1-minute towards a total time of 1000 HOURS before major maintenance? Even assuming for some reason that you cut the number of hours by a factor of 10 to 100 HOURS the jet stage has accumulated almost no significant time towards major maintenace as compared to the rocket.
And again, given current flight rates, if purely rocket powered assist system which actually does 30 annual flights would require one(1) major overhaul that's hardly a showstopper. Yes, technically jet stage wouldn't probably require maintenance at all in years but in practice I presume you would have to, due time alone and for harsh usage / unconventional orientation. Tried to look for maintenance plans for fighter jet engines, no luck. Do you have any references?
IIRC fighter engines are "swapped out" ever 1000 hours of operation and sent in for minor maintenance and storage. Something like every 10,000 hours they are sent in for major maintenance and parts replacement and again put in storage.
(Swap-outs I'd probably better say are done with engines FROM storage just so there's no confusion :) )

You can probably find some information from museums or folks that maintain historic records. My experiance is working around the flight line but not directly on the engines or aircraft. I've had to 'help' at points in my career though :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline JasonAW3

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Re: Jet Powered First Stage
« Reply #120 on: 02/22/2013 08:05 pm »
If it hasn't been pointed out yet,

     Numerous designs for use of jet engines for a first have been suggested and even used to a limited extent, but unless rocket motors are vastly cheaper than jet engines, I figure, with appropriate anti-FOD screens over the inlets, a reusable vertical launch jet powered first stage is actually quite possible.

     Even if you assume using all of the available jet fuel for launch, you should be able to design the stage with doors that would snap shut after the engines shut down at altitude and be water proof enough to allow a parachute assisted landing to occur in the ocean.  Should you have a five to ten percent remainder of fuel, (Allowing for the stage having SOME aerodynamic characteristics of its' own) you should be able to at least shorten the recovery trip by flying at least part way back to the launch facility before ditching in the ocean.  Given enough fuel margin, it might even be able to land vertically at or near the launch site for reuse.

Just a thought...

Jason
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Re: Jet Powered First Stage
« Reply #121 on: 02/23/2013 11:28 am »
Jets and Ramjets

OK I have to skip large chunks and just leave those in the "mileages vary" section, otherwise this leads to chain reaction and Chris runs out of server space. Great discussion though  ;D

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Jet engines in general and military engines specifically are designed to have no issues what-so-ever running in ANY orientation. That said however part of the "modifications" that P&W were talking about were to allow them to START while vertical and to maintain a pressurized system during the entire flight regime.
(While a jet will RUN in any position they are not generally designed to START in any position. However this isn't really a major issue and was expected to be a very easy and cheap "mod" to do.
Interesting, start on the ground or airstart? I'd venture to guess the jet stage continues on arc so high it flames out? Have faint recollection of reading about some sort of turning nozzle in the inlet, that turns into scooping air while the jet stage falls down. Kind of thrust reverser but in the other end. Just realized that I have no idea how the TVC is supposed to be done in the jet stage, gotta reread the thread from the beginning...

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Understood but a blow-down system that can then throttle back UP is NOT so simple. Look at the LM pressure-fed, throttlable system.
Forgot to say that if the initial rocket boost and ramjet part are integral there's no need to throttle back up. Also no hybrid systems can be used. System with separate pressurant tank and usually HX is blowdown while valve to HX is closed.


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Then you don't use a ramjet at all. It won't do you any "good" that way. No time to ramp up thrust and no time for the ISP modification to kick in. The normal "rocket" trajectory is not going to allow any time for a ramjet to work.
Wait a minute, what's a special ramjet optimized trajectory going to look like? Much flatter than standard issue gravity turn? Actually, how can you do anything but the gravity turn without a) wings or b) high AOA ? I was under impression that the jet stage is just ring of jet engines around rest of the rocket. The rocket part doesn't like neither wings nor high AOA because structural loads that otherwise would not be there. Which brings the whole thing to the question of how far you optimize which part. Jets would love to linger in the atmosphere, rocket would like to get out of it ASAP. If you do a flat gravity turn that is good for the jet part then rocket starts at orientation where it is forced to fly in high AOA to start gaining altitude.

I would at least consider a system where the assist stage consists of very simple pressure-fed initial rocket boost of high T/W (As much as the rocket part can handle, possibly >2) to enable quick ramjet start. I realize that this surely isn't optimum for inlets etc. aiming for high supersonic or even low hypersonic airbreating boost regime but I wouldn't try that with v1.0 system. RENE would compliment the initial boost nicely and actually be part of the ramjet so the whole system starts to look like RBCC.

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Marquardt engineers were quoted as saying they couldn't see any reason why the BOMARC ramjets couldn't operate up to Mach-10 except for the "little" fact that the airframe fell apart well before then : )
Didn't one BOMARC actually stampede and try this but made "only" mach 5 because run out of gas :)

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MIPCC (Mass Injection Pre-Compression/Compressor-Cooling for those who don't know :) ) is useful to both extend the range of and increase the thrust of, (at a cost of ISP because you're exepending more "propellant") any airbreathing system.

Curious, if using methane as fuel could it be used in MIPCC system? Cryogenic, much higher autoignition temperature than conventional jet fuels and AFAIK the burning process is relatively slower. Would it be possible to spray it before the flame holder to achieve compression effect.

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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #122 on: 02/26/2013 05:54 pm »
Jets and Ramjets

OK I have to skip large chunks and just leave those in the "mileages vary" section, otherwise this leads to chain reaction and Chris runs out of server space. Great discussion though  ;D
Or worse... Critical mass is reached and the forum disappear into a black hole only to appear around a machine planet in a distant galaxy! Or was that a movie? :)

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Jet engines in general and military engines specifically are designed to have no issues what-so-ever running in ANY orientation. That said however part of the "modifications" that P&W were talking about were to allow them to START while vertical and to maintain a pressurized system during the entire flight regime.
(While a jet will RUN in any position they are not generally designed to START in any position. However this isn't really a major issue and was expected to be a very easy and cheap "mod" to do.
Interesting, start on the ground or airstart?
Ground start in a vertical position originally. A "side" benifit though was they could then be started in ANY position really. Once the machinary is moving, (say for airstart you simply allow the compressor/turbine assembly to windmill) everything is flowing properly anyway since the fluids have bladders and pressurization to keep them going under all flight conditions.

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I'd venture to guess the jet stage continues on arc so high it flames out?
Depends really. The "original" idea had them running out of fuel just after they detached as individual pods. (IIRC it was noted that with no other input power or action the "vehicle" would then coast up to around 90,000ft before starting to come back down. Typically the F100-229 is "listed" as operating to around 50,000ft normally. If you can keep the engines at or below that they probably shouldn't flame-out)

I don't see why you'd have to have them flame-out as with the booster-ring you can just throttle back a bit for staging and then use aerodynamic and thust vectoring to ensure you don't go so high as to flame-out. "My" preference would be to include enough fuel to fly-back and land at the launch site. Dani Eder's Booster Ring would have the engines idle along ballistically until used at the last minute to land down-range for re-fueling and then fly it back to the lanch site. The NASA-Dryden concept uses parachutes to bring the stage down almost to a landing, with the engines at idle until the last minute landing on a barge at sea and then either shipping the stage back or re-fueling and flying it back.

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Have faint recollection of reading about some sort of turning nozzle in the inlet, that turns into scooping air while the jet stage falls down. Kind of thrust reverser but in the other end. Just realized that I have no idea how the TVC is supposed to be done in the jet stage, gotta reread the thread from the beginning...
Several different methods and reasons are given in and around the concepts :)

You'd want TVC for take off and initial flight so you can direct the vehicle and probably the best bet would be a simple movable ring-and/or-nozzle/deflector arrangment. The "thing" you're looking to prevent is having the engine ingest air "up-its-exhaust" because this will blow-out your combustion chamber flame-holders. So the majority of ideas look for a way to maintain "forward" speed enough to idle the engines. As I mentioned above Dani-Eder simply keeps the engines idling enough to overcome the back-pressure, while the NASA-Dryden folks keep the intakes pointed "down" until it gets near landing where it turns around and lands vertically. In a similar manner my preference is to fly back to near the launch site and then land vertically.

You don't really need a specific intake shaped vent to allow a jet engine to "back" down for a landing but you DO want to have as little interference as possible so most high performance jets today have what are known as "suck-in" doors along the length of the inlet. These doors are spring-loaded to be open when the ram-air-flow in the inlet is low such as during take off and allow the compressor to easily draw in large amounts of air. Once ram pressure reaches a certain point they close off to allow the air inlet to shape and ingest the majority of the air.

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Then you don't use a ramjet at all. It won't do you any "good" that way. No time to ramp up thrust and no time for the ISP modification to kick in. The normal "rocket" trajectory is not going to allow any time for a ramjet to work.
Wait a minute, what's a special ramjet optimized trajectory going to look like? Much flatter than standard issue gravity turn? Actually, how can you do anything but the gravity turn without a) wings or b) high AOA ? I was under impression that the jet stage is just ring of jet engines around rest of the rocket.
The "turbojet/fan" is pretty much "gravity" turn trajectory, (slightly shallower AoA but not that much) however a RAMJET needs speed to get going, (again you're looking around Mach-1+) unless it's a subsonic ramjet and/or a RENE system which pretty much only works up TO around Mach-2.
The suggested ramjet stage (Glenn Olson, or NASA-Dryden concepts, Dani-Eder prefers a "simple" TSTO rocket set up and my "prefference" isn't set yet I could "see" the uses but it might be better to go with rockets and avoid the hassle :) ) is different in that the ramjet is designed and built to operate from Mach-2 up. As part of this concept, the ramjet stage would take over acelleration around Mach-2.5 and continue almost to Mach-5 or better which would require a more "depressed" air-breathing trajectory between 50,000 and 100,000ft to allow for the ramjet operation.

As such both the ramjet stage and the final rocket stage would have to be Supersonic lifting bodies. Really not as bad as it sounds though as body-lift at supersonic speeds is pretty good. Once the ramjet reached staging speed it would perform a TVC/Aerodynamic pitch-up and climb until the ramjets shut down at which point the rocket stage would release and light up the rockets for final climb into and boost to orbital speed.

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The rocket part doesn't like neither wings nor high AOA because structural loads that otherwise would not be there. Which brings the whole thing to the question of how far you optimize which part. Jets would love to linger in the atmosphere, rocket would like to get out of it ASAP. If you do a flat gravity turn that is good for the jet part then rocket starts at orientation where it is forced to fly in high AOA to start gaining altitude.
(Actually, rockets WANT a "high-AoA" because it is less structural and aerodynamic loading. AoA being flight-path/trajectory above the local horizon)

It's part of the various trade offs for the system. If you just use the jet-booster ring your rocket is going to get a speed boost of around Mach-2 and start out around 50,000ft at a pretty high AoA (around 70-degrees) very similar to a "normal" rocket launch. If you add a ramjet stage you increase your overall ISP gain at the cost of having to have a more robust, less "rocket-like" trajectory from 50Kft to 100Kft and more aerodynamic and heating loads.

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I would at least consider a system where the assist stage consists of very simple pressure-fed initial rocket boost of high T/W (As much as the rocket part can handle, possibly >2) to enable quick ramjet start. I realize that this surely isn't optimum for inlets etc. aiming for high supersonic or even low hypersonic airbreating boost regime but I wouldn't try that with v1.0 system. RENE would compliment the initial boost nicely and actually be part of the ramjet so the whole system starts to look like RBCC.
The Boeing study came to the conclusion you want at least 2-gs of thrust at take off for optimum performance. As long as your orbital rocket stage can "handle" that kind of loading it probably doesn't matter all that much what your initial stage(s) are.
The biggest "issue" with aiming for high-supersonic/low-hypersonic (this would be Mach-4.5 and above BTW just so we're clear) air-breathing is that it is the very hardest PART of the air-breathing regime to manage and almost impossible without adjustable intakes and exhausts on the airbreathing engines. A fixed-inlet/exhaust ramjet that operates from Mach-2 to almost Mach-5 is one thing. One that operates from Mach-4 to almost Mach-8 is another and one that operates only from Mach-4 to around Mach-5 is probably not that useful as an acellerator.

I'd actually "prefer" and RBCC system but the problem with those is that we haven't actually flown one yet and it would end up being a full engine development program even if we can "assume" being able to build on previous research. Ever time anyone comes close to actually building and fight testing a working example the program seems to get cut no matter which government agency is doing the funding. (I'm sensing a pattern here :) )

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Marquardt engineers were quoted as saying they couldn't see any reason why the BOMARC ramjets couldn't operate up to Mach-10 except for the "little" fact that the airframe fell apart well before then : )
Didn't one BOMARC actually stampede and try this but made "only" mach 5 because run out of gas :)
I can neither confirm nor deny... And the sad part is I actually can't :)

I've done research and can't find any actual "evidence" of a run-away BOMARC, though I got an answer back to that question from an ex-engineer who says they did have a run-away, possibly at White Sands, (test launches from Eglin were "wired" to blow up if they went out of control at all or over a certain speed so as not to "alert" the Soviet spy trawlers to the missiles true capabilities) but I can't confirm anything, and nothing "official" exists stating anything :)

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MIPCC (Mass Injection Pre-Compression/Compressor-Cooling for those who don't know :) ) is useful to both extend the range of and increase the thrust of, (at a cost of ISP because you're exepending more "propellant") any airbreathing system.

Curious, if using methane as fuel could it be used in MIPCC system? Cryogenic, much higher autoignition temperature than conventional jet fuels and AFAIK the burning process is relatively slower. Would it be possible to spray it before the flame holder to achieve compression effect.
I don't recall any ideas/concepts where ANY cryogenic fuel was proposed for MIPCC, I suspect mostly because of auto-ignition and back-flare issues. (Having your fuel explode in BETWEEN your compressor blades is always a 'bad' thing :) )
The problem would be in the gas/air mixture ratio at any point in the flow-path but especially as it enters the combustion chamber. If you can get the ratio exactly right you wouldn't need to inject fuel into the combustion chamber, but if you're off at all either you'll have flame outs or auto-ignition in an unstable manner. The reason RASCAL used LOX was to avoid instability issues at high Mach/Altitude and so as not to interfere with the standard fuel/air ratio in the combustor.
(For a ramjet this is probably a lot less of an issue)

At higher speeds you also have the issue with possible eddy-flows within an engine (again this is a bit less of an issue with ramjets but they DO depend on some eddy-flow to keep the flame-holders lit and flame expansion uniform) which can cause autoignition and hot-spots.

LNG/Methane is an often prefered fuel to Liquid Hydrogen, (the Air Force would MUCH rather deal with it than LH2 if at all possible for operational purposes :) ) due to its higher density over LH2 and though it's a bit slower burning it is actually easier to combust stably than LH2 or so I've read.

As far as I'm aware the only 'cryo' MIPCC exeriments done have used LOX (RASCAL/DARPA) and LN2 (Dutch Royal Military Collage) and both of those were directed at using the most "benign" injectent possible.

Randy
(Agree some good back-and-forth going on :)
From The Amazing Catstronaut on the Black Arrow LV:
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Offline RanulfC

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Re: Jet Powered First Stage
« Reply #123 on: 02/27/2013 04:14 pm »
I don't have anything against wings/tailplanes, but doubt that a vehicle that would actually work like that would have very little to do with original F-1e. Bit dubious that exhaustive redesign was actually done. Same problem as with F-5/StratoLaunch. Ordinary liquid rockets are pretty flimsy sacks of propellant. It's marketed as great achievement if they manage to just stand up on their own on the pad without internal pressure! ;) Now take that, flip horizontally and attach from the top to a carrier plane, or attach a wing on top of it. It's going to buckle without some serious reinforcement.
As an example of what I'd consider a GOOD B.O.T.E. series of assumptions for turning a rocket into a usable Air-or-Launch-Assist vehicle is from the following web-site:
http://en.wikibooks.org/wiki/Space_Transport_and_Engineering_Methods/Human_Transport

Specifically. "Alternative Launchers: Jet Booster" by Dani Eder. Using the jet-booster ring to deliver a "Falcon-1-Like" Two-stage rocket vehicle to 15km and 480m/s (@50,000ft and Mach-1.6) with each stage being fully recoverable and providing half the final required delta-V for a circular 200km (Equatorial) orbit.

"Jet Boost:
The Stratolaunch system currently in development uses a subsonic carrier aircraft. The Jet boost launcher uses military fighter engines to reach supersonic speeds and higher altitudes. Both systems share the idea of using air-breathing engines for the early part of the flight, which are 4-20 times as efficient as rocket engines. They also avoid using rocket engines in the least efficient part of their operating range: going vertically, which causes gravity loss, and through dense air where you have drag and engine pressure loss. Jet boost dispenses with most of the carrier aircraft by using vertical launch and landing. Using wings allows getting more mass off the ground, but they also limit operating altitude. Less hardware to develop should lower the development cost. The engines are mounted to a Booster Ring, which in turn carries the rocket stage. The booster ring lifts the rocket to around 15 km altitude and 480 m/s (Mach 1.6) velocity. The rocket ignites and continues it's flight from there, while the booster ring returns to a vertical landing at the launch site.

For human transport, the minimum capacity is 1 person. Extrapolating from the SpaceX Dragon capsule mass, which carries up to 7 people, we estimate total mass to orbit as 1,500 kg, of which 750 kg is passenger and life support, or uncrewed low g cargo. In an early version the Skyhook would not be present and the launcher is used to deliver the first components for orbital assembly. Air-breathing boosters function better with more air, so unlike an all-rocket system, they prefer to launch at low altitude. We assume a sea-level equatorial launch site. For a 200 km altitude circular orbit a delta V of 7,900 m/s is required from 15 km, including potential and kinetic energy. The Earth's rotation contributes 465 m/s, and gravity, drag, and pressure losses are assumed to be 200 m/s from that starting altitude. Therefore the net velocity for the rocket stages is 7635 m/s.

We assume a re-used two stage chemical rocket with exhaust velocity of 3350 m/s, similar to the SpaceX Merlin 1C extended nozzle engine. Since ignition of the rocket is at altitude, we optimize it for vacuum thrust, which is effectively the operating condition after the first 20 seconds of operation. We increase the Falcon inert mass from 6.5% of stage mass to 11% of stage mass to account for heat shield and other stage recovery hardware so it can be used again. Each stage is assigned 50% of the required velocity, so the calculations are as follows:

Stage 2 delta-V = 3817 m/s. Mass ratio = 3.125, so final mass = 32% of start mass. Stage inert = 11% x 68% of start mass = 3.5% of start mass. Thus payload = 28.5% of start mass, and also equal to 1500 kg from above. Therefore Stage 2 start mass = 5,263 kg.

Stage 1 delta-V = 3818 m/s. Mass ratio = 3.126, so final mass = 32% of start mass. Stage inert = 11% x 68% of start mass = 3.5% of start mass. Thus Stage 2 + Payload (what the first stage has to carry) = 28.5% of start mass, and also = 5263 kg, thus Start mass = 18,467 kg, which we round up to 18,500 kg.

A modern fighter engine such as the PW F-135 generates 191 kN thrust on full afterburner at sea level. For performance reasons, we want to take off at 2.0 gravities, thus the allowed mass is 9.74 tons per engine. The engine itself (1700 kg) , fuel (450 kg), and booster ring hardware (590 kg) has an estimated mass of 2.74 tons .

Thus each engine can lift 7 tons of rocket stages and payload, and we need 3 engines for the 18.5 ton rocket with some margin.

The net payload to orbit of 4% of the rocket initial mass is not remarkable, but the ability to recover and use all the stages repeatedly is.

Liftoff mass of the booster ring + rocket is 26.72 tons, about an order of magnitude smaller than the Falcon 9 vehicle + Dragon capsule, and it should therefore be proportionally less expensive to develop."

As noted the vehicle stage inert mass is increased from a "Falcon" current 6.5% to 11% to include structural reinforcement and recovery equipment. Total payload is @750kg or a little over 1600lbs. I consider the margin in the design pretty good but welcome comment :)

I've corresponded with Mr. Eder and he says he prefers a jet-assisted-TSTO for the concept at this point but would use a ramjet later with a Light-Gas-Gun and ram-boosted projectile mass launcher system.

He notes that using a ramjet stage of course reduces your rocket to a single stage at the cost of possibly needing more structural dry mass and higher aero/heating loads.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #124 on: 02/27/2013 05:03 pm »
If it hasn't been pointed out yet,

     Numerous designs for use of jet engines for a first have been suggested and even used to a limited extent, but unless rocket motors are vastly cheaper than jet engines, I figure, with appropriate anti-FOD screens over the inlets, a reusable vertical launch jet powered first stage is actually quite possible.
It's been pointed out a few times :) It never hurts though to make sure everyone is on the same page :)

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Even if you assume using all of the available jet fuel for launch, you should be able to design the stage with doors that would snap shut after the engines shut down at altitude and be water proof enough to allow a parachute assisted landing to occur in the ocean.  Should you have a five to ten percent remainder of fuel, (Allowing for the stage having SOME aerodynamic characteristics of its' own) you should be able to at least shorten the recovery trip by flying at least part way back to the launch facility before ditching in the ocean.  Given enough fuel margin, it might even be able to land vertically at or near the launch site for reuse.

Just a thought...
Designing for fly-back and vertical landing is (IMHO) the overall best option with possibly a landing/recovery down-range if need be for performance boosting.

The Jet-engine first stage should have enough on-board propellant and aerodynamics to do a turn and powered return and landing.

The "big" hurdle for RTLS (Return-To-Launch-Site) for a second stage is the time/distance factor of how far down-range it gets compared to the energy needed for the RTLS mission. The NASA-Dryden concept has the ramjet stage coming down 175 nautical miles (a little over 200 miles/341km) down-range which is much harder. Once the ramjet stage "looses" the rocket it has effectivly lost its ability to fly efficently at ramjet speeds because the upper stage was in effect the "inlet" for the engines. So flame-out is pretty much a given, hence there won't be any way to power the stage back without adding more equipment of limited use.

The good news of course is being really "simple" (mechanically at least :) ) engines the ramjets are pretty much immune to water immersion and can be made pretty robust, so an ocean recovery is much more viable than for turbojet/fan engines. The bad news is that's a stage you have to find a way to recover, ship back, and refurbish before you can launch it again.

In some ways that makes the idea of using jet-boost as a simple "assist" stage and leaving the rest of the propulsion to a couple of robust, reusable rocket stages take the payload to orbit. You're still going to end up recovering a "stage" somewhere a long way down-range in either case though. (Actually further with the rocket than the ramjet)

One thing that R7 and I have touched on is combining engine types in a concept known as RBCC (Rocket Based Combined Cycle) engines. By combining a rocket engine within a ramjet engine and using the rockets exhaust to entrain air with the "ejector" effect you can effectivly "start" a ramjet at zero-speed. If you keep enough propellant you can then use the rockets to provide fly-back ability. There's a penelty in mass though that may not be affordable for distances such as those of the second stage.
Another consideration is a "Supercharged-Ejector-Ramjet" (SERJ) which has a "fan" (usually a one or two-stage compressor fan) which increases the basic ejector ramjet performance at low-to-medium speeds and would provide a much higher propellant efficiency than rockets for the fly-back mission. Unfortunatly they would add some complexity and mass to the basic stage as well as either having to be designed to be removed from the airstream in high speed flight or capable of "windmilling" with low drag at high Mach speeds. (Not so easy to do in either case)

My "leaning" in this situation is to stick to a simple, robust ramjet stage and make more of them to have "on-hand" when/if flight rates increase. Again YMMV and I'd like to hear other opinions :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Tass

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Re: Jet Powered First Stage
« Reply #125 on: 02/27/2013 10:33 pm »

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #126 on: 02/28/2013 11:52 am »
11% x 68% = 3.5%

Eh?
Full is:
"Stage inert = 11% x 68% of start mass = 3.5% of start mass."

Which is still "geek" to me but I'll ask :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #127 on: 02/28/2013 12:08 pm »
Oh and apologies to R7, Mr. Eder noted to me that while the Boeing study did not include a second air-breathing stage he said that the AoA of a ramjet would probably still stick pretty close to a nominal "rocket" trajectory between 50Kft to 100Kft (probably closer to 150Kft) though the speed would produce a higher aero-heating/load between Mach-2 and around Mach-5/6 before a rocket stage took over.

Also, found this report on NTRS:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19850012934_1985012934.pdf
It's a short study paper on a European design for an air-breathing/rocket combined powerplant launch vehicle. It is a 1.5 Stage-To-Orbit vehicle (based on the "BETA" SSTO study vehicle by MBB) using a ramjet "half-stage" which fire-up a bit over Mach-1 after the rockets launch the vehicle and then take over acelleration till around Mach-6.5 and 150Kft+ where they are staged and the rockets fire to continue the flight to orbit.
The "gain" over the pure-rocket version is listed both as "propellant" savings (the point R7 was making) but also in total reduction of overall vehicle gross-mass and structure. (300 tonnes for the MBB SSTO, meanwhile the "Istra" vehicle comes in at a little over 150 tonnes, with both capable of placing a 15-tonne payload into a 200km circular orbit)

Mr. Eder noted that Boeing, using aircraft manufacturing methodology always favored smaller airframes if possible due to less expensive development and production costs which is an "aim" of this vehicle.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline R7

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Re: Jet Powered First Stage
« Reply #128 on: 02/28/2013 03:52 pm »
Great posts/links again, gotta digest those some more :)

But to clear bit of confusion:
(Actually, rockets WANT a "high-AoA" because it is less structural and aerodynamic loading. AoA being flight-path/trajectory above the local horizon)

I think we have different idea what AoA stands for. Not a professional so I used it as the wiki explains it:

http://en.wikipedia.org/wiki/Angle_of_attack

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Angle of attack is the angle between the body's reference line and the oncoming flow.

I assume that for a rocket the reference line is it's longitudinal axis. For ordinary rocket gravity turn the 'nose' always points straight into the flow (same direction as velocity vector) so AoA remains zero (neglecting any wind) even as the trajectory turns.

Angle between flight path and local horizon is pitch angle, no? Rocket starts that as 90 degree and then gravity turns it.
AD·ASTRA·ASTRORVM·GRATIA

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #129 on: 02/28/2013 04:59 pm »
Great posts/links again, gotta digest those some more :)
Ok... it's been five minutes... You done yet? :)

Seriously take y'time
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But to clear bit of confusion:
(Actually, rockets WANT a "high-AoA" because it is less structural and aerodynamic loading. AoA being flight-path/trajectory above the local horizon)

I think we have different idea what AoA stands for. Not a professional so I used it as the wiki explains it:

http://en.wikipedia.org/wiki/Angle_of_attack

Quote
Angle of attack is the angle between the body's reference line and the oncoming flow.

I assume that for a rocket the reference line is it's longitudinal axis. For ordinary rocket gravity turn the 'nose' always points straight into the flow (same direction as velocity vector) so AoA remains zero (neglecting any wind) even as the trajectory turns.

Angle between flight path and local horizon is pitch angle, no? Rocket starts that as 90 degree and then gravity turns it.
I admit to mis-using the term :) Angle-To-The-Local-Horizon, or "pitch-angle" is more correct. I got used to using "AoA" in relation to Air-Launch where you want a high AoA (70-degrees or better) which IS in relation to the "forward velocity reference line" for that particular case. My bad :)

In this particular case it would be more akin to a normal rocket launch and pitch is probably a better term.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Danderman

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Re: Jet Powered First Stage
« Reply #130 on: 02/28/2013 10:50 pm »
If it hasn't been pointed out yet,

     Numerous designs for use of jet engines for a first have been suggested and even used to a limited extent, but unless rocket motors are vastly cheaper than jet engines, I figure, with appropriate anti-FOD screens over the inlets, a reusable vertical launch jet powered first stage is actually quite possible.

     Even if you assume using all of the available jet fuel for launch, you should be able to design the stage with doors that would snap shut after the engines shut down at altitude and be water proof enough to allow a parachute assisted landing to occur in the ocean.  Should you have a five to ten percent remainder of fuel, (Allowing for the stage having SOME aerodynamic characteristics of its' own) you should be able to at least shorten the recovery trip by flying at least part way back to the launch facility before ditching in the ocean.  Given enough fuel margin, it might even be able to land vertically at or near the launch site for reuse.

Just a thought...

Jason

I would guess that Someday Now, such a system would be in common use. It makes sense for a first stage to carry jet engines for liftoff and descent.

The design described above of a jet-assisted rocket that would ignite at altitude is extremely interesting, saving an order of magnitude in first stage mass is quite revolutionary.

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #131 on: 03/04/2013 03:11 pm »
11% x 68% = 3.5%

Eh?
Full is:
"Stage inert = 11% x 68% of start mass = 3.5% of start mass."

Which is still "geek" to me but I'll ask :)
Recieved a reply on the question:
On 2/28/2013 7:42 AM, Campbell, Randy E Civ USAF AFMC 581 MMXS/MXDPABD
wrote:
> Had question on something that was pointed out to me:
> On the web-page/book, under Alternative Launchers, Jet Boost you
> show the calculations for the two stages of the rocket powered
> vehicle. 
> The listing for the second stage says:
> " Stage 2 delta-V = 3817 m/s. Mass ratio = 3.125, so final mass = 32%
> of start mass. Stage inert = 11% x 68% of start mass = 3.5% of start
> mass. Thus payload = 28.5% of start mass, and also equal to 1500 kg
> from above.
> Therefore Stage 2 start mass = 5,263 kg"
>
> Specifically I'm confused as to what is being "said" here:
> "Stage inert = 11% x 68% of start mass = 3.5% of start mass"

This is what is known in the field as a "math error" :-) It should be as
follows:

Mass ratio of 3.125 implies 68% of stage start mass is burned as fuel.
Design assumption is a reusable stage will have hardware mass of 11% of fuel mass, higher than the 6.5% found on the Falcon 9, to account for longer fatigue life on the structure, and re-entry and landing hardware 11% of 68% = 7.5% (not 3.5%) of total mass at stage ignition.

I corrected all the subsequent numbers on the page.  We need 4 engines instead of 3 now.

Dani"

Good catch and thanks for pointing that our :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #132 on: 03/04/2013 04:49 pm »
Though Glenn Olson's "Alt-Accel" website has been shut-down for quite a while the data and articles are still accessable at the "pulse-jets.com" site and downloadable from this post:
http://www.pulse-jets.com/phpbb3/viewtopic.php?f=4&t=5201&p=62265&hilit=alt.accel.com#p61547

This includes the ARLA and POGO concepts as well.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Jet Powered First Stage
« Reply #133 on: 03/11/2013 06:37 pm »
Back on-topic sort-of, I found this report during the search that is interesting:

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930084872_1993084872.pdf

http://aerade.cranfield.ac.uk/ara/1957/naca-tn-3922.pdf

"Analytical Investigation of the Effect of Water Injection on Supersonic Turbojet-Engine-Inlet Matching and Thrust Augmentation"

The basic idea is that along with the thrust augmentation effect, water-injection showed promise of allowing fixed supersonic inlets to
operate more efficiently in off-nominal conditions and at higher altitudes.
In supersonic flight one issue with a fixed, or non-moving/non-adjustable inlet is that above a certain (design) speed the inlet begins to "spill" excess airflow that it cannot "ingest" properly which increases drag (and hence fuel consumption) greatly.

The "simple" answer to this issue is to provide the inlet with the mechanical ability to "adjust" itself to match the airstream by having
movable cone/spike/ramps or cowling/nacelle lips. These are usually (and especially early on, the report was published in 1957) complex and heavier than a simple "fixed" inlet however and since normally full-afterburner and/or thrust augmentation was needed to reach and maintain these higher speeds these systems were seen as probably being too much "effort" for what was going to be a "dash" or short-operation-time system. So the idea of using evaporative cooling to decrease the "spillage" (by increasing density) of the incoming air stream seemed like a good "short-duration" idea.

If I read this report correctly this study showed that the idea offered several advantages as well as some additional drawbacks of the concept. For one thing the additional thrust augmentation (noted to be between 20% to 130% that of a non-augmented fixed inlet design) allowed a greatly reduced fuel consumption (at the cost of having the water injection system and water which was "assumed" to replace fuel capacity in the first place) due to lower afterburner settings along with an overall "net" thrust increase due to less "spilled" airflow. At "equivalent" thrust levels fuel consumption for the water-injection engine dropped by between 16% and 60% of the compared types. Engine airspeed limits were found to be increased up to 25% with similar loss of ISP due to water (liquid) expenditure being added to the formula. Lastly added thrust capability of the water-injection engine allowed a considerable increase in flight altitude limits compared to
non-augmented engines.

Increased engine performance and materials advances along with longer operational requirements for high speeds meant that this concept was not used in service. Mechanically adjustable inlets were adopted instead to allow a larger "nominal" operations envelope along with higher "bypass" ratio engines for increased thrust capability.

Both the thrust augmentation and increased Mach and altitude capability would be useful for a jet powered booster vehicle, and the storage, pumping and injection system are not that much a mass penalty when compared to the overall system mass and benefit gained.

I have not yet found anything relevent to R7s question of using cryogenic Methane to both deep cool a ramjet and as fuel. I've shot off a note to an actual "Ramjet" expert to get his opinion. He's got some good information on ramjets and integral-rocket-ramjet engines on his blog which can be found here:
http://exrocketman.blogspot.com/2012/12/ramjet-cycle-analyses.html

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

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