Author Topic: DARPA ALASA  (Read 24475 times)

Offline jongoff

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DARPA ALASA
« on: 03/29/2014 03:45 AM »
I'm not sure if there's already a thread on ALASA, but here's an announcement about Boeing's concept that was selected for Phase 2 funding:

http://www.boeing.com/boeing/Features/2014/03/bds_darpa_contract_03_27_14.page

It's an interesting concept. It uses and F15 (so probably going to do a zoom climb before separation), and while it has two stages, there are only one set of engines, and they're on the upper stage--it looks like the first stage is just a drop tank.

With launch at high altitude and with a zoom climb, they can probably keep the rocket delta-V to orbit down in the ~8km/s range, and the engines can be nearly vacuum optimized without too much overexpansion at ignition. It would seem like the thrust two weight ratio once the first stage has burned out may be an issue, but maybe they're running the stages blow-down, or maybe the upper stage is just running at lower pressure?

Definitely a DARPA-weird concept, but I don't see anything about it that is technically infeasible. I hope they can make all the details work and make it to flight. I'm not very confident that Boeing can make this work at the price-point that they were hoping for ($1M/flt), but I think they've got a reasonable chance of at least making it work.

~Jon

Online Blackstar

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Re: DARPA ALASA
« Reply #1 on: 03/29/2014 11:12 AM »
ALASA

Offline gosnold

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Re: DARPA ALASA
« Reply #2 on: 03/29/2014 01:40 PM »
Any idea about the kind of propellant used? Liquid would probably need to be pumped to the top of the rocket, but swapping from one solid motor compartment to another with the same nozzle seems complicated.

Online edkyle99

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Re: DARPA ALASA
« Reply #3 on: 03/29/2014 01:54 PM »
Boeing's press release says that the first two stages use the same engines, which doesn't rule out a third, or fourth, or more stages. 

Nice Skunk Works misdirection, too, after all of that early talk about dual hypersonic mini-B-70s, etc.  This idea looks simple by comparison, even elegant.  The only question is can it be pulled off in the real world?  Margins are tiny from the outset - in mass, yes, but especially in cost.

 - Ed Kyle
« Last Edit: 03/29/2014 02:15 PM by edkyle99 »

Offline Skyrocket

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Re: DARPA ALASA
« Reply #4 on: 03/29/2014 04:16 PM »
Another illustration by Boeing

Offline Proponent

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Re: DARPA ALASA
« Reply #5 on: 03/29/2014 05:46 PM »
Any idea about the kind of propellant used? Liquid would probably need to be pumped to the top of the rocket, but swapping from one solid motor compartment to another with the same nozzle seems complicated.

If you really wanted to use solids, maybe you could use the same trick as Orion's LAS:  essentially have the solids fire forward into a U-shaped duct.  Just thinking out loud.  I seems highly unlikely to me that anyone would actually want to do this.

If the propellant is liquid, it's going to have to be fed into the combustion chamber at high pressure anyway.  I wouldn't guess that pumping from a rearward location would be a huge deal.  If you had to pump it 2 m forward at 10 Gs acceleration, the hydrostatic head would be on the order of 2 atm.

Offline hop

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Re: DARPA ALASA
« Reply #6 on: 03/29/2014 07:43 PM »
If you really wanted to use solids, maybe you could use the same trick as Orion's LAS:  essentially have the solids fire forward into a U-shaped duct.
Also other tractor type escape towers. However, since it has a drop tank we can rule out solids.

Quote
If you had to pump it 2 m forward at 10 Gs acceleration, the hydrostatic head would be on the order of 2 atm.
Since the same engines are used for the 1st and 2nd stage, it's a fair bet the first stage will be relatively low T/W.

Offline RanulfC

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Re: DARPA ALASA
« Reply #7 on: 04/01/2014 02:51 PM »
Off-Topic note: Those engines are stolen from KSP! I recognize the "radial" engine set!

On-Topic: I thought I'd suggested such a set up before and seem to recall that I was told it wouldn't work "well" for an LV. I was under the impression that "tractor" rocket designs had some significant issues?

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

Offline rusty

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Re: DARPA ALASA
« Reply #8 on: 04/04/2014 05:55 PM »
Another illustration by Boeing

I don't see how that can put 100lbs into orbit and considering how much even an AIM-120 costs, how they expect to do it for $1mil/flt. Article mentions a launch at 40,000ft (well below an F-15's ceiling) with the first two stages using common tractor engines. There's a lot missing here, including an adequate payload bay, so I can only conclude Boeing through Phantom Works got a chunk of cash to do some PR shots (like with the CST-100).
In that regard, this is a success as I've always dug the McDonnell Douglas F-15
« Last Edit: 04/04/2014 05:56 PM by rusty »

Offline gosnold

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Re: DARPA ALASA
« Reply #9 on: 04/04/2014 06:58 PM »
Off-Topic note: Those engines are stolen from KSP! I recognize the "radial" engine set!

On-Topic: I thought I'd suggested such a set up before and seem to recall that I was told it wouldn't work "well" for an LV. I was under the impression that "tractor" rocket designs had some significant issues?

Randy

Well if you put them close to the fuselage you have to put them at an angle, which is less efficient (you have "cosine losses").
An interesting aspect of tractor configuration is that you can save mass on structural elements since you pull instead of pushing, so you don't have to worry about buckling.


Offline RanulfC

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Re: DARPA ALASA
« Reply #10 on: 04/04/2014 07:52 PM »
I don't see how that can put 100lbs into orbit and considering how much even an AIM-120 costs, how they expect to do it for $1mil/flt. Article mentions a launch at 40,000ft (well below an F-15's ceiling) with the first two stages using common tractor engines. There's a lot missing here, including an adequate payload bay, so I can only conclude Boeing through Phantom Works got a chunk of cash to do some PR shots (like with the CST-100).
In that regard, this is a success as I've always dug the McDonnell Douglas F-15

At a "guess" (speculation mode engaged) I'd say that it would be a lot cheaper off the bat than an AIM-120 as the majority cost item for the AMRAAM is the seeker and control set. A pure "launch" guidence system is pretty inexpensive. The launch altitude is probably significant in that at 40,000ft in a near vertical climb the Eagle is still under acceleration so is providing more significantly towards the total Delta-V budget than if it launched at 80,000ft and almost no airspeed or engine thrust left, As for the payload bay I'm guessing it is actually the "nose-cone" and it's a fairing with engines below that. It looks to be skinner, but longer than the ASAT missile. (Speculation Mode disengaged)

Really they need to drop the F-15 and keep the engines :) A pair of jet-pods with F100s and enough fuel for the job would be about the size of a pair of cruise missiles and be able to stage the LV at over 80,000ft and Mach-2 while returning to land at the launch site.

Well if you put them close to the fuselage you have to put them at an angle, which is less efficient (you have "cosine losses").
An interesting aspect of tractor configuration is that you can save mass on structural elements since you pull instead of pushing, so you don't have to worry about buckling.

The cosine losses weren't what I seem to recall everyone talking about. I seem to recall that the exhaust impingment was considered a "serious" issue though I'm not sure why.

The main "advantage" aspect I was looking for at the time was putting the engines high above the surface for landing without sending debris all over at high velocity. I'd like to actually see more tractor concepts :)

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

Offline Misha Vargas

Re: DARPA ALASA
« Reply #11 on: 04/05/2014 09:04 PM »
I know this design is not a staged design, but couldn't a tractor-style second stage have the ability to fire from the beginning of launch, reducing dead weight and lower the size of the first stage engines? Isn't this what the Shuttle was, in a sense? Also, if Boeing's design requires pumping fuel up from the drop tanks, could a staged design not pump fuel from the first stage into the second? (A sort of "vertical crossfeed".)

This has been floating around in my brain for a long time, and I can't figure out where (or if) I'm crazy.

Offline simonbp

Re: DARPA ALASA
« Reply #12 on: 04/06/2014 01:19 AM »
Are all four engines burning after it drops the drop tank? I hope the payloads are rated for 10+ g acceleration...

Offline jongoff

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Re: DARPA ALASA
« Reply #13 on: 04/06/2014 04:47 AM »
Are all four engines burning after it drops the drop tank? I hope the payloads are rated for 10+ g acceleration...

They may just drop the pressure a bunch for the upper stage. You'd need a good injector (pintle or swirler) to make it work, but if the first stage had a higher pressure and the upper stage has a lower pressure, you could keep the thrust levels reasonable.

~Jon

Offline simonbp

Re: DARPA ALASA
« Reply #14 on: 04/06/2014 05:44 PM »
Maybe, but the engines would need to throttle down a lot to keep the burn time long enough to end up with an orbit close to circular.

It would seem simpler if the first stage/zoom climb inject the vehicle on a pop-up trajectory, so after separation the second stage coasts to apogee and then does a quick, high-thrust circularization burn. It's killer for the payload, but really minimizes gravity losses. Plus, it would mean that you could launch to a range of inclinations from a single site and not have to worry about dropping stuff downrange.

ALASA is all about launching small recon/comm sats to LEO at strange inclinations, so that would seem to fit. I'm starting to understand why Boeing won.

Offline Zed_Noir

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Re: DARPA ALASA
« Reply #15 on: 04/07/2014 01:30 AM »
Can the 1st stage burn be pump-feed and the 2nd stage burn be pressure-fed? Presumably the pump gets discarded with the 1st stage. It would be something like the propellants gets pumped from the 1st stage tankage to the 2nd stage tankage to the combustion chambers for the 1st stage burn.

Offline Misha Vargas

Re: DARPA ALASA
« Reply #16 on: 04/07/2014 03:22 PM »
Can the 1st stage burn be pump-feed and the 2nd stage burn be pressure-fed? Presumably the pump gets discarded with the 1st stage. It would be something like the propellants gets pumped from the 1st stage tankage to the 2nd stage tankage to the combustion chambers for the 1st stage burn.

I'm not clear on terminology. By staging, you're referring to the Boeing proposal, not traditional staging (like I proposed a few posts back), right? Are drop tanks stages? Wiki says no, Boeing (or at least Steve Johnston) says yes...huh.

Offline simonbp

Re: DARPA ALASA
« Reply #17 on: 04/07/2014 09:43 PM »
That is one of those "how many angels can dance on the head of a pin" questions. A better question would be if any flown launch vehicle has used drop tanks on engines that continued to fire after the tank was dropped (unlike Shuttle). Old Atlas did the opposition (dropping booster engines while the sustainer continued to fire), but I can't think of any flown vehicles with drop tanks.

Usually you want to get rid of all the mass you can as quickly as you can. Boeing has to have some very good reason for keeping all four engines through second stage burnout.
« Last Edit: 04/07/2014 09:48 PM by simonbp »

Offline Skyrocket

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Re: DARPA ALASA
« Reply #18 on: 04/07/2014 10:36 PM »
but I can't think of any flown vehicles with drop tanks.

Proton-M Briz-M uses a drop tank on the Briz-M upperstage.

Offline francesco nicoli

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Re: DARPA ALASA
« Reply #19 on: 04/07/2014 11:10 PM »
just for the sake of curiosity: did you try it? :P

Offline simonbp

Re: DARPA ALASA
« Reply #20 on: 04/08/2014 07:59 PM »
but I can't think of any flown vehicles with drop tanks.

Proton-M Briz-M uses a drop tank on the Briz-M upperstage.

Did not know that; thanks!

Offline RanulfC

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Re: DARPA ALASA
« Reply #21 on: 04/08/2014 08:48 PM »
but I can't think of any flown vehicles with drop tanks.

Proton-M Briz-M uses a drop tank on the Briz-M upperstage.

Did not know that; thanks!

...And currently for all we know it could drop a couple engines with the tank/1st stage :)

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

Offline Zed_Noir

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Re: DARPA ALASA
« Reply #22 on: 04/09/2014 02:35 AM »
Can the 1st stage burn be pump-feed and the 2nd stage burn be pressure-fed? Presumably the pump gets discarded with the 1st stage. It would be something like the propellants gets pumped from the 1st stage tankage to the 2nd stage tankage to the combustion chambers for the 1st stage burn.

I'm not clear on terminology. By staging, you're referring to the Boeing proposal, not traditional staging (like I proposed a few posts back), right? Are drop tanks stages? Wiki says no, Boeing (or at least Steve Johnston) says yes...huh.
Technically the 1st stage as I described it would not be classified as a drop tank since there will be propellant pumps aboard.

Offline ChrisWilson68

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Re: DARPA ALASA
« Reply #23 on: 04/09/2014 04:58 AM »
The launch altitude is probably significant in that at 40,000ft in a near vertical climb the Eagle is still under acceleration so is providing more significantly towards the total Delta-V budget than if it launched at 80,000ft and almost no airspeed or engine thrust left

No.  Whether the Eagle is under acceleration or not is irrelevant.  All that matters is the altitude and velocity at the time of separation.  And a lower altitude will only be a win if the velocity is enough to reach the higher altitude at a coast -- which it will not even be close to for the 40kft versus 80kft you're talking about.  So it would in fact be far better to launch at low airspeed at 80kft than mach 2-3 at 40kft.

The reason they're planning to launch at 40kft is probably that the launch vehicle weighs so much that the F-15 can't get much higher than that while carrying it.

Offline RanulfC

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Re: DARPA ALASA
« Reply #24 on: 04/09/2014 02:43 PM »
The launch altitude is probably significant in that at 40,000ft in a near vertical climb the Eagle is still under acceleration so is providing more significantly towards the total Delta-V budget than if it launched at 80,000ft and almost no airspeed or engine thrust left

No. Whether the Eagle is under acceleration or not is irrelevant.

uhm, not really actually. Part of the whole "80,000ft" issue is the F-15 doesn't do WELL at that altitude. In a zoom-climb it would be almost completely out of energy with little aerodynamic authority. It does much better at Mach-2 and 40,000ft. Sorry I wasn't clear about that.

Quote
All that matters is the altitude and velocity at the time of separation.  And a lower altitude will only be a win if the velocity is enough to reach the higher altitude at a coast -- which it will not even be close to for the 40kft versus 80kft you're talking about. So it would in fact be far better to launch at low airspeed at 80kft than mach 2-3 at 40kft.

And of the two, altitude and velocity, the velocity at the time of "launch" is the more important factor from all the air-launch research I've read. Mach-2 at 40,000ft is much more of an advantage than Mach-0.98 at 80,000ft. In addition AoA is also a huge factor in Air Launch and the fact the F-15 will have a high AoA will help a lot.

Quote
The reason they're planning to launch at 40kft is probably that the launch vehicle weighs so much that the F-15 can't get much higher than that while carrying it.

I have no doubt of that considering it probably masses around the same as the ASM-ASAT missile: (http://en.wikipedia.org/wiki/ASM-135_ASAT) which means the F-15 will be lucky to launch at supersonic speed at all.

Which as I said before, means they are wasting far to much mass on a manned/aircraft launch platform :) Guess I should get "back-to" playing around with the jet engine launch assist concept again...

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

Offline gosnold

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Re: DARPA ALASA
« Reply #25 on: 06/30/2014 07:41 PM »
Jeff Foust has more info on ALASA:
http://www.spacenews.com/article/military-space/40769darpa-developing-operational-pathfinder-for-alasa-air-launch-system
Quote
The engines are powered by an unusual mixture of nitrous oxide and acetylene.

Offline catdlr

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Re: DARPA ALASA
« Reply #26 on: 02/05/2015 09:30 PM »
ALASA concept Video

Published on Feb 5, 2015
DARPA’s Airborne Launch Assist Space Access program (ALASA) seeks to propel 100-pound satellites into low Earth orbit (LEO) within 24 hours of call-up, all for less than $1 million per launch. The current ALASA design envisions launching a low-cost, expendable launch vehicle from conventional aircraft. Serving as a reusable first stage, the plane would fly to high altitude and release the launch vehicle, which would carry the payload to the desired location. The program is moving ahead with rigorous testing of new technologies that one day could enable revolutionary satellite launch systems that provide more affordable, routine and reliable access to space.


« Last Edit: 02/05/2015 11:16 PM by catdlr »
Tony De La Rosa

Offline Saltvann

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Re: DARPA ALASA
« Reply #27 on: 02/05/2015 09:42 PM »
Here's their press release:

http://www.darpa.mil/NewsEvents/Releases/2015/02/05.aspx

A test flight in late 2015 and 12 orbital test flights in 2016.

Offline Skyrocket

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Re: DARPA ALASA
« Reply #28 on: 02/05/2015 11:04 PM »
ALASA concept Video





According to the video, the drop-tank concept apparently has been dropped.

Offline RanulfC

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Re: DARPA ALASA
« Reply #29 on: 02/06/2015 07:44 PM »
Uhm, it drops off the F-15 and deploys a ballute so it then goes HORIZONTAL where the engine ignites and THEN has to do another PULL-UP manuever?
(banging my head on the desk several times)

Nope, STILL doesn't make any sense to me.

IF (as I suspect is the case) the AF is worried about a "launch incident" with a liquid propellant LV on the F-15 drop the ballute and use a small solid "seperation" stage to allow the F-15 to pull away. The ballute would even be "ok" if they ignited the main stage BEFORE it looses the critical launch AoA but the video doesn't inspire me that this will get much futher as is.

As for the change from the drop-tank to intergrated "first-stage" it makes me wonder how long before the rockets get moved to the tail as per "normal"

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

Online kevin-rf

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Re: DARPA ALASA
« Reply #30 on: 02/06/2015 08:02 PM »
Stupid question, I watched with the sound off, but four engines on the first and second stage. Does that mean they are hoping to reduce costs by eliminating the engine gimbals and use differential thrust for steering?

Four engines is really cheaper and more controllable than one engine per stage with gimbals?
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Offline RanulfC

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Re: DARPA ALASA
« Reply #31 on: 02/06/2015 08:09 PM »
Stupid question, I watched with the sound off, but four engines on the first and second stage. Does that mean they are hoping to reduce costs by eliminating the engine gimbals and use differential thrust for steering?

Four engines is really cheaper and more controllable than one engine per stage with gimbals?

"Cheaper" may actually be relative here, remember who's (and ultimatly who the user is) program this is :)

Mechanically less complex but I suspect not as flexible (no pun intended but then again there it is :) ) as a single gimbled motor. "Cheap" 3D printed nozzles/engines maybe?

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

Offline Zed_Noir

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Re: DARPA ALASA
« Reply #32 on: 02/07/2015 07:16 AM »
Stupid question, I watched with the sound off, but four engines on the first and second stage. Does that mean they are hoping to reduce costs by eliminating the engine gimbals and use differential thrust for steering?

Four engines is really cheaper and more controllable than one engine per stage with gimbals?

IMO the 4 engines reduce the interstage separation distance resulting in a more compact vehicle.


...

As for the change from the drop-tank to intergrated "first-stage" it makes me wonder how long before the rockets get moved to the tail as per "normal"


The way they mounted the engines in the video avoids a tailcone ejection event and changes to the vehicle center of gravity and aerodynamics drag profile. Beside they need to place the drogue chute in the tail.

Offline dchill

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Re: DARPA ALASA
« Reply #33 on: 02/07/2015 06:00 PM »
The ballute looks like a single point failure to me, if that's their way of guaranteeing stability prior to the start of powered flight.  Passive stability (when there are two humans a few feet away) shouldn't require an active device like an inflation system.  My guess would be before it gets through safety review they'll need to add something like fins (and maybe end up going to 3 stages due to the added weight).
« Last Edit: 02/07/2015 06:00 PM by dchill »

Offline Zed_Noir

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Re: DARPA ALASA
« Reply #34 on: 02/08/2015 02:33 AM »
The ballute looks like a single point failure to me, if that's their way of guaranteeing stability prior to the start of powered flight.  Passive stability (when there are two humans a few feet away) shouldn't require an active device like an inflation system.  My guess would be before it gets through safety review they'll need to add something like fins (and maybe end up going to 3 stages due to the added weight).

The drogue chute is quite similar to the units used for stabilizing various ordnance drop by the various US military forces for decades. Your fin stabilization idea would require pop-out and active control features for the vehicle IMO. 

The F-15 Strike Eagle might not be physically able to accommodate a larger three stage vehicle. Also there is a weight limitation to how much the fuselage hardpoint/bomb rack can carry.
« Last Edit: 04/16/2015 09:32 AM by Zed_Noir »

Offline fast

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Re: DARPA ALASA
« Reply #35 on: 04/16/2015 08:37 AM »
Uhm, it drops off the F-15 and deploys a ballute so it then goes HORIZONTAL where the engine ignites and THEN has to do another PULL-UP manuever?
(banging my head on the desk several times)

Nope, STILL doesn't make any sense to me.

IF (as I suspect is the case) the AF is worried about a "launch incident" with a liquid propellant LV on the F-15 drop the ballute and use a small solid "seperation" stage to allow the F-15 to pull away. The ballute would even be "ok" if they ignited the main stage BEFORE it looses the critical launch AoA but the video doesn't inspire me that this will get much futher as is.

As for the change from the drop-tank to intergrated "first-stage" it makes me wonder how long before the rockets get moved to the tail as per "normal"

Randy

exactly. first stage tractor is a total nonsense if no drop tanks.
why just don't use this traditional approach???

Offline john smith 19

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Re: DARPA ALASA
« Reply #36 on: 04/16/2015 09:41 AM »
From the Faust article

"The engines are powered by an unusual mixture of nitrous oxide and acetylene."

Acetylene?

That's quite interesting as it's been a perennial possible fuel for decades.

I wonder how they've managed to curb it's tendency to explode.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Steven Pietrobon

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Re: DARPA ALASA
« Reply #37 on: 05/23/2015 05:26 AM »
They probably mix it with another chemical, quite possibly acetone.
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Offline Skyrocket

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Re: DARPA ALASA
« Reply #38 on: 05/23/2015 09:28 AM »
Generally i am wondering about the safety and stability of a monopropellant mixture of nitrous oxide and acetylene.

Offline john smith 19

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Re: DARPA ALASA
« Reply #39 on: 06/17/2015 08:44 AM »
They probably mix it with another chemical, quite possibly acetone.
Doubtful.

Acetylene tanks use this with IIRC powdered rare earth to absorb the Acetylene.

This is way too heavy for flight weight tanks for a pump fed engine, not to mention the performance loss.
[EDIT2 Opps. I may have been premature thinking of pump feds. Checking physical properties I note N2O2 liquifies around -88c and Ethyne solidifies at about -80c.

This suggests a sort of "aerosol can" architecture, with tanks at a few bar feeding pumps or higher pressure systems running a few 10s of bar, all running around -70 to -80c to keep the propellants dense ]


[EDIT obvious question but does anyone have any idea what sort of Isp you could get out of this propellant at a viable engine chamber pressure? My instinct is 30-100 atm, maybe as low as 10, but that's just a feeling and I can't back it up. Obviously higher pressure --> small chamber(s) --> lower mass but also harder driven pumping system.

It's interesting the US military don't like cryogenics but are OK with things that will vaporize at room temperature and remain dangerous (like a cloud of Ethyne) ]

 
« Last Edit: 06/17/2015 09:42 AM by john smith 19 »
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Offline Kryten

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Re: DARPA ALASA
« Reply #40 on: 10/07/2015 08:58 PM »
Quote
Jeff Foust ‏@jeff_foust  3m3 minutes ago
[DARPA's Pam] Melroy: doing static ground tests of ALASA’s mixed monopropellant now. First launch? “more to tell” in the spring. #ispcs

Offline arachnitect

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Re: DARPA ALASA
« Reply #41 on: 11/30/2015 01:38 PM »
Air launch plans shelved due to safety concerns:

http://spacenews.com/darpa-airborne-launcher-effort-falters/

Quote
WASHINGTON – The U.S. Defense Advanced Research Projects Agency has scrapped plans to launch small satellites from a modified F-15 fighter jet after two tests of a new rocket fuel ended in explosions this year.

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Re: DARPA ALASA
« Reply #42 on: 11/30/2015 03:10 PM »
Has any thought been given to using a drone rather than a manned aircraft, for these launches?  They fly F-4s and F-16s converted to QF-4s and QF-16s as aerial targets at Tyndall.  These can apparently either auto-land or be controlled by a remote pilot for landing if needed.

 - Ed Kyle
« Last Edit: 11/30/2015 03:14 PM by edkyle99 »

Offline Skyrocket

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Re: DARPA ALASA
« Reply #43 on: 11/30/2015 03:14 PM »
Has any thought been given to using a drone rather than a manned aircraft, for these launches?  They fly F-4s converted to QF-4s as aerial targets at Tyndall.  These can apparently either auto-land or be controlled by a remote pilot for landing if needed.

 - Ed Kyle

I guess, this might be an option for the future - but one of the basic ideas for ALASA was to use an unmodified carrier plane for highest possible flexibility.

Offline TrevorMonty

Re: DARPA ALASA
« Reply #44 on: 11/30/2015 04:58 PM »
At least XS1 is still alive and kicking for now.

Offline Skyrocket

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Re: DARPA ALASA
« Reply #45 on: 11/30/2015 05:07 PM »
BTW: here is a patent application: NITROUS OXIDE FUEL BLEND MONOPROPELLANTS

http://www.faqs.org/patents/app/20090133788

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Re: DARPA ALASA
« Reply #46 on: 11/30/2015 05:22 PM »
Has any thought been given to using a drone rather than a manned aircraft, for these launches?  They fly F-4s converted to QF-4s as aerial targets at Tyndall.  These can apparently either auto-land or be controlled by a remote pilot for landing if needed.

 - Ed Kyle

I thought the last QF-4's where retired this year, leaving only the smaller QF-16's.

http://www.airforcetimes.com/story/military/2015/05/30/qf4-targeting-drone-last-flight/28015077/
« Last Edit: 11/30/2015 05:24 PM by kevin-rf »
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Offline savuporo

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Re: DARPA ALASA
« Reply #47 on: 11/30/2015 05:41 PM »
How does that affect SALVO which was supposed to be a sort of pathfinder ?

http://spacenews.com/40769darpa-developing-operational-pathfinder-for-alasa-air-launch-system/
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Offline sunbingfa

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Re: DARPA ALASA
« Reply #48 on: 11/30/2015 06:08 PM »
Bummer. I'm really looking forward to this project because it's quite different from things going on anywhere else and it's potentially revolutionary to commercial and military small satellite launch. Just ~2weeks ago there are reports saying ALASA is still on track, but now the news is that the failure occurred early this year. Hoping for more updated information released, although I know it's probably not easy for DARPA

Offline dror

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Re: DARPA ALASA
« Reply #49 on: 11/30/2015 07:33 PM »
Air launch plans shelved due to safety concerns:

http://spacenews.com/darpa-airborne-launcher-effort-falters/

Quote
WASHINGTON – The U.S. Defense Advanced Research Projects Agency has scrapped plans to launch small satellites from a modified F-15 fighter jet after two tests of a new rocket fuel ended in explosions this year.

It also says:
Quote
As a result, DARPA has abandoned plans, described in the agency’s 2016 budget request, to conduct as many as a dozen ALASA test flights during the upcoming year.
-They have canceled plans for testing in 2016. Naturally.
And
Quote
Boeing, subcontractor Orbital ATK of Dulles, Virginia, and DARPA nonetheless plan to continue developing the technology. A third propellant test is imminent.
-They continue to develop and test the propelant.

So I'm confused.  Is it canceled?
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Offline Zed_Noir

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Re: DARPA ALASA
« Reply #50 on: 11/30/2015 07:50 PM »
Has any thought been given to using a drone rather than a manned aircraft, for these launches?  They fly F-4s and F-16s converted to QF-4s and QF-16s as aerial targets at Tyndall.  These can apparently either auto-land or be controlled by a remote pilot for landing if needed.

 - Ed Kyle

As posted up thread. The QF4 are retire.

The QF-16 is not capable of carrying the ALASA stack.

Maybe they can modified a few mothballed F-15s into QF-15 launcher drones.

Offline a_langwich

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Re: DARPA ALASA
« Reply #51 on: 11/30/2015 08:02 PM »
So I'm confused.  Is it canceled?

Not yet.  Just the flight tests have been put on hold.  The contractors will have to show a little more safety before flight tests can start. 

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Re: DARPA ALASA
« Reply #52 on: 11/30/2015 08:03 PM »
BTW: here is a patent application: NITROUS OXIDE FUEL BLEND MONOPROPELLANTS

http://www.faqs.org/patents/app/20090133788

Is this the group that developed NOFBx, which became In-Space Propulsion (ISP) ?
NOFBx was de-manifested from the Dragon external cargo run to the ISS after their own energetic happenings.
Is there a link to a discussion of the monopropellant fuel for ALSA?
Can we conclude that a monopropellant system is necessary for ALSA to adequately reduce cost and complexity?
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline a_langwich

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Re: DARPA ALASA
« Reply #53 on: 11/30/2015 08:15 PM »
Can we conclude that a monopropellant system is necessary for ALSA to adequately reduce cost and complexity?

I don't think so.  DARPA doesn't do many projects where we know enough to conclude a particular approach must be used; instead we don't know ANY approach that works, and particular teams take a shot at the problem with a high failure rate. 

I think monoprop was just a choice by this team.  That choice was probably driven by looking at how energetic this propellant was, then seeing it might work as a mono, and looking at the cost and complexity reductions that resulted.  But now, looking at propellant stability, it might make more sense to separate the energetics.

Online edkyle99

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Re: DARPA ALASA
« Reply #54 on: 11/30/2015 10:35 PM »
Has any thought been given to using a drone rather than a manned aircraft, for these launches?  They fly F-4s converted to QF-4s as aerial targets at Tyndall.  These can apparently either auto-land or be controlled by a remote pilot for landing if needed.

 - Ed Kyle

I thought the last QF-4's where retired this year, leaving only the smaller QF-16's.

http://www.airforcetimes.com/story/military/2015/05/30/qf4-targeting-drone-last-flight/28015077/
QF-4s are still flying at Holloman AFB.  https://www.flightglobal.com/news/articles/usaf-qf-4s-set-for-2017-out-of-service-date-418868/

The drone control systems are installed by BAE Systems in Mojave, so it seems likely that F-15 could be so equipped if funding were provided.

 - Ed Kyle
« Last Edit: 11/30/2015 10:37 PM by edkyle99 »

Offline Zed_Noir

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Re: DARPA ALASA
« Reply #55 on: 11/30/2015 11:27 PM »
Has any thought been given to using a drone rather than a manned aircraft, for these launches?  They fly F-4s converted to QF-4s as aerial targets at Tyndall.  These can apparently either auto-land or be controlled by a remote pilot for landing if needed.

 - Ed Kyle

I thought the last QF-4's where retired this year, leaving only the smaller QF-16's.

http://www.airforcetimes.com/story/military/2015/05/30/qf4-targeting-drone-last-flight/28015077/
QF-4s are still flying at Holloman AFB.  https://www.flightglobal.com/news/articles/usaf-qf-4s-set-for-2017-out-of-service-date-418868/

...

 - Ed Kyle

It is not clear if the QF-4s at Holloman AFB are in the USAF inventory. They could be counted as contractor operated hardware. In any casr there is not much point in modifying and upgrading them for a new role.


Offline jcm

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Re: DARPA ALASA
« Reply #56 on: 12/01/2015 04:42 AM »
How does that affect SALVO which was supposed to be a sort of pathfinder ?

http://spacenews.com/40769darpa-developing-operational-pathfinder-for-alasa-air-launch-system/

I am wondering the same thing. Anyone have an update on SALVO?
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