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 )Recall that ALL stages and parts are recovered after the mission so while this is basically a 3STO it is STILL and RLV.
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.
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.
Again from another thread:Quote from: PatchouliKeep 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
Quote from: RanulfC on 05/20/2011 07:54 pmAgain from another thread:Quote from: PatchouliKeep 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.RandyCould 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.
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.
Quote from: Danderman on 05/10/2011 06:20 pmIgnoring 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.
Quote from: RanulfCAgain from another thread:Quote from: PatchouliKeep 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?
Again from another thread:Quote from: PatchouliKeep 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.
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...
I would suggest the KISS principle...
... when invoking jet engines; use existing engines without modifications.
The already existing B1B can carry 56,700kg maybe more if fuel is off loaded.
Quote from: Patchouli on 05/26/2011 07:54 pmThe 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/1591/1The tail mounted SSME in the 747 would not be needed with uprated engines.
what does 3D printing bring to the table?It doesn't change the rocket equation or make the idea viable.
Quote from: Jim on 08/10/2011 12:14 pmwhat 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.
Quote from: Jim on 08/10/2011 03:02 pmI 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
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
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
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)
The "Jet Powered First Stage" concept itself is viable as long as it's contributory towards lowering operations and standing costs.
The rocket must gain 100,000 feet from launch altitude using rocket propulsion.
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?
Quote from: RanulfC on 08/10/2011 03:56 pmThe rocket must gain 100,000 feet from launch altitude using rocket propulsion. It fails this requirement.
Quote from: RanulfC on 08/10/2011 03:54 pmEh, 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 payload2) 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
Quote from: Jim on 08/10/2011 03:58 pmQuote from: RanulfC on 08/10/2011 03:56 pmThe 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
Quote from: RanulfC on 08/10/2011 06:49 pmQuote from: Jim on 08/10/2011 03:58 pmQuote from: RanulfC on 08/10/2011 03:56 pmThe 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.Randya 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.
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.
Quote from: RanulfC on 08/10/2011 07:06 pmOk 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/
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.
Staging at altitude, at velocity, at an angle is where things get murky I guess.
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.
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.
Quote from: Danderman on 05/21/2011 11:19 pmI 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.
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.
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.
Quote from: Carreidas 160 on 08/11/2011 11:24 amQuote from: RanulfC on 08/10/2011 07:06 pmOk 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 from: RanulfC on 08/11/2011 01:56 pmQuote from: Carreidas 160 on 08/11/2011 11:24 amQuote from: RanulfC on 08/10/2011 07:06 pmOk 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...
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>
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.
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
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..
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 .
While the linear turbine/rocket MIGHT be "low-tech" has anyone actually built a flying model?
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.
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.
Again, not even close but I somehow don't think you're even reading what I'm writing at this point. Still...
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.pdfhttp://settlement.arc.nasa.gov/Nowicki/SPBI104.HTMRam-Rocket:http://caius.utias.utoronto.ca/rbcc.htmlAnd 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.pdfhttp://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADB121965&Location=U2&doc=GetTRDoc.pdfhttp://gltrs.grc.nasa.gov/reports/1997/TM-107422.pdf
QuoteAgain, 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 ?
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 "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 ??
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.
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
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.
first your misconception in vertical launch assist rocket approach is that rocket stages will be unusable,...
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 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.
Fine by me. Your loss.Randy
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,
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.
Quote from: RanulfC on 05/26/2011 09:16 pmAhhh, 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,
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.
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.pdfThis 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.
Quote from: intlibber on 09/20/2011 12:10 amYeah, 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 .
QuoteAs 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.pdfThis 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.
Quote from: john smith 19 on 09/20/2011 07:02 amQuote from: intlibber on 09/20/2011 12:10 amYeah, 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.
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.
Quote from: RanulfC on 09/20/2011 04:38 pmQuote from: john smith 19 on 09/20/2011 07:02 amQuote from: intlibber on 09/20/2011 12:10 amYeah, 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.
That said, I would also point out that supersonic british delta winged bomber.
Quote from: mlorrey on 09/21/2011 12:45 amQuote from: RanulfC on 09/20/2011 04:38 pmQuote from: john smith 19 on 09/20/2011 07:02 amQuote from: intlibber on 09/20/2011 12:10 amYeah, 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.
Quote from: Downix on 09/21/2011 04:40 pmQuote from: mlorrey on 09/21/2011 12:45 amAllegedly, 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.
Quote from: mlorrey on 09/21/2011 12:45 amAllegedly, 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.
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.
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.
How to make maximum *effective* use of the space in the cargo plane of your choice is still an open question
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 smith19Personally 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.
You wrote:QuoteHow to make maximum *effective* use of the space in the cargo plane of your choice is still an open questionWhich 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 from: RanulfC on 09/26/2011 05:10 pmThe 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.
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.
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 usehttp://en.wikipedia.org/wiki/Commercial_Application_of_Military_Airlift_Aircraft
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.
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.
in the end advantage if is, is so small, then whats a point ?
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).
Quote from: HMXHMX on 09/30/2011 05:27 pmQuickReach 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
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.
Unfortunatly "internal-carry" for air-launch isn't possible with the way they are laid out unless major modifications to the airframe are done.
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)
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
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.htmhttp://www.up-ship.com/apr/extras/scruiser1.htmhttp://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADB143755http://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 )
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.
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.
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.QuoteMy 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.
Quote from: RanulfC on 09/28/2011 08:45 pmUnfortunatly "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.
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.
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?
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*.
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.
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.
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.
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.
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.
crap just got real! (Well, a bit less speculative at least...) Go Burt & Paul!http://www.stratolaunch.com/
Jet/Air-breathing Launch assist
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.
Quote from: RanulfC on 02/19/2013 04:05 pm Jet/Air-breathing Launch assistIs 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.
Quote from: RanulfC on 02/20/2013 02:52 pmOne 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.
QuoteThe 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?
QuoteIt 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.
QuoteRamjets 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.
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.
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.
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.
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.
(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 )
jet-assist seems to be the most near-term, easily fielded type of launch assist.
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
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...
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?"
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 )
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.)
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.
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%20CategoriesQuoteDuring 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.
No reason why a rocket engine can't have cumulative operation time measured in hours. And they have demonstrated that.
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.
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?
This is where I just respectfully disagree LV manufacturer who already does rocket engines can field a rocket engine with more ease.
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
Quote from: RanulfC on 02/20/2013 08:54 pmI'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-vehicleA 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.
QuoteAs 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?
QuoteActually 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.
QuoteThe "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.
QuoteRamjets 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.
QuoteNASA-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
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.
Going to break this up into sections if y'all don't mind
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!
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.
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.
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.
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.
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
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.
QuotePS 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.
Quote from: RanulfC on 02/22/2013 03:15 pmGoing to break this up into sections if y'all don't mind Yes these are getting a bit long Stupid message edit screen is ridiculously small for these...oh wait you can actually drag it bigger. Wohoo!
QuoteTheir 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.
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
Quote from: RanulfC on 02/22/2013 06:30 pmThe 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=2147485147F-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'
Before you dismiss the "wing/tailplane" (just like the Pegasus) you might consider that performance enhanment is in SPITE of the extra mass
Quote from: RanulfC on 02/22/2013 03:15 pmI'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.
QuoteThe 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.
QuoteThe 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
QuoteBecause 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.
Quote from: RanulfC on 02/22/2013 03:15 pmthe 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.
QuoteAssuming 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?
Jets and Ramjets
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.
Understood but a blow-down system that can then throttle back UP is NOT so simple. Look at the LM pressure-fed, throttlable system.
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.
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 : )
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.
Quote from: RanulfC on 02/22/2013 04:52 pmJets and RamjetsOK 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
QuoteJet 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...
QuoteThen 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.
Quote 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
QuoteMIPCC (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 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.
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...
11% x 68% = 3.5%
Quote from: RanulfC on 02/27/2013 04:14 pm 11% x 68% = 3.5%Eh?
(Actually, rockets WANT a "high-AoA" because it is less structural and aerodynamic loading. AoA being flight-path/trajectory above the local horizon)
Angle of attack is the angle between the body's reference line and the oncoming flow.
Great posts/links again, gotta digest those some more
But to clear bit of confusion:Quote from: RanulfC on 02/26/2013 05:54 pm(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_attackQuoteAngle 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.
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
Quote from: Tass on 02/27/2013 10:33 pmQuote from: RanulfC on 02/27/2013 04:14 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