Author Topic: Towed Glider Air-Launch System (TGALS)  (Read 16219 times)

Online catdlr

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Towed Glider Air-Launch System (TGALS)
« on: 02/03/2015 05:26 pm »
Towed Twin-Fuselage Glider Launch System (CGI Animation)

Published on Feb 2, 2015
The towed glider is an element of the novel rocket-launching concept of the Towed Glider Air-Launch System (TGALS). The TGALS demonstration’s goal is to provide proof-of-concept of a towed, airborne launch platform.

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Offline NovaSilisko

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #1 on: 02/03/2015 05:35 pm »
Interesting idea, but I'm unsure what advantage this has over a traditional air launch solution. I guess you can make the glider go much steeper and faster than you safely could with a manned launch platform? But if that's the case, seems to me like it would end up being less complex to make the aircraft self-propelled and unmanned, instead of having to coordinate two aircraft at once.

I have to admit, the extreme barrel roll at 1:25 made me burst out laughing   :P
« Last Edit: 02/03/2015 05:37 pm by NovaSilisko »

Offline pagheca

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #2 on: 02/03/2015 06:22 pm »
The sweep angle of the glider looks no more than 30 deg, meaning that its speed cannot be much more than ~Mach 1.3.

So, where is the advantage respect to a subsonic aircraft? Where am I wrong or there is a way to design a high supersonic wing of that type?

p.s. there is a prototype actually flying:

http://www.nasa.gov/centers/armstrong/Features/TGALS_first_flight.html#.VNEgOVXF-OU
« Last Edit: 02/03/2015 06:26 pm by pagheca »

Offline jongoff

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #3 on: 02/03/2015 07:42 pm »
There are all sorts of advantages of a concept like this. Right now there are very few good airlaunching aircraft options. Existing planes all force you to very narrow body diameters, and custom planes are rarely cost effective unless there are other users (ie LauncherOne benefits a lot from having SS2 provide most of the demand for WK2, so it only has to buy flights "by the drink"). This gives you the benefit of a custom aircraft at a much lower price, and could likely scale up to nearly stratolaunch sizes.

Also, because it's unmanned, zoom climbs like they show provide a huge flight-path-angle advantage. Staging subsonic at high altitude and a good flight path angle can knock your remaining dV to orbit down to around 8km/s (from a typical 9600m/s for ground launch).

The one thing I don't get is why they do a drop-and-light. They'd be better off lighting the rocket, and using it for the pitchup maneuver--that way you can verify the rocket engine is working before you release it from the glider. I guess if that rocket is a solid booster, you don't want to light a firecracker off attached to your vehicle, but if it's a liquid fueled system, lighting it and using it for the pitchup thrust is a great way of doing the equivalence of SpaceX's pre-launch hold-downs.

But all told, this is a really neat concept, even if I have minor quibbles about a few design choices. I actually had been wanting to do something like this for a proposed effort a few years ago, so glad someone else did it first.

~Jon

Offline Lars-J

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #4 on: 02/03/2015 11:27 pm »
There are all sorts of advantages of a concept like this. Right now there are very few good airlaunching aircraft options. Existing planes all force you to very narrow body diameters, and custom planes are rarely cost effective unless there are other users (ie LauncherOne benefits a lot from having SS2 provide most of the demand for WK2, so it only has to buy flights "by the drink"). This gives you the benefit of a custom aircraft at a much lower price, and could likely scale up to nearly stratolaunch sizes.

Also, because it's unmanned, zoom climbs like they show provide a huge flight-path-angle advantage. Staging subsonic at high altitude and a good flight path angle can knock your remaining dV to orbit down to around 8km/s (from a typical 9600m/s for ground launch).

The one thing I don't get is why they do a drop-and-light. They'd be better off lighting the rocket, and using it for the pitchup maneuver--that way you can verify the rocket engine is working before you release it from the glider. I guess if that rocket is a solid booster, you don't want to light a firecracker off attached to your vehicle, but if it's a liquid fueled system, lighting it and using it for the pitchup thrust is a great way of doing the equivalence of SpaceX's pre-launch hold-downs.

But all told, this is a really neat concept, even if I have minor quibbles about a few design choices. I actually had been wanting to do something like this for a proposed effort a few years ago, so glad someone else did it first.

~Jon

I don't see the real benefit of this. You still need to make a custom carrier aircraft / drone, and now you have converted a relatively simple air launch concept into one that requires TWO stages before the rocket even is dropped (the aircraft pulling, then the carrier)

And scaling this up would be difficult - but that is a problem shared with all air launch concepts.

Offline Rocket Science

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #5 on: 02/03/2015 11:43 pm »
Why not place two turbofans over each fusalage and make do without the tow? But that's just me...
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Offline jongoff

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #6 on: 02/04/2015 01:04 am »
There are all sorts of advantages of a concept like this. Right now there are very few good airlaunching aircraft options. Existing planes all force you to very narrow body diameters, and custom planes are rarely cost effective unless there are other users (ie LauncherOne benefits a lot from having SS2 provide most of the demand for WK2, so it only has to buy flights "by the drink"). This gives you the benefit of a custom aircraft at a much lower price, and could likely scale up to nearly stratolaunch sizes.

Also, because it's unmanned, zoom climbs like they show provide a huge flight-path-angle advantage. Staging subsonic at high altitude and a good flight path angle can knock your remaining dV to orbit down to around 8km/s (from a typical 9600m/s for ground launch).

The one thing I don't get is why they do a drop-and-light. They'd be better off lighting the rocket, and using it for the pitchup maneuver--that way you can verify the rocket engine is working before you release it from the glider. I guess if that rocket is a solid booster, you don't want to light a firecracker off attached to your vehicle, but if it's a liquid fueled system, lighting it and using it for the pitchup thrust is a great way of doing the equivalence of SpaceX's pre-launch hold-downs.

But all told, this is a really neat concept, even if I have minor quibbles about a few design choices. I actually had been wanting to do something like this for a proposed effort a few years ago, so glad someone else did it first.

~Jon

I don't see the real benefit of this. You still need to make a custom carrier aircraft / drone, and now you have converted a relatively simple air launch concept into one that requires TWO stages before the rocket even is dropped (the aircraft pulling, then the carrier)

And scaling this up would be difficult - but that is a problem shared with all air launch concepts.

Gliders are a lot easier to scale, and a lot cheaper than traditional aircraft. The pulling aircraft can more likely be something that can fly in other revenue service arrangements than a dedicated air launcher. It is somewhat rube golberg, but that's not always bad.

~Jon

Offline jongoff

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #7 on: 02/04/2015 01:04 am »
Why not place two turbofans over each fusalage and make do without the tow? But that's just me...

Oh yeah, no worries, just add a full-blown propulsion system. No biggie. :-)

~Jon

Offline Danderman

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #8 on: 02/04/2015 01:06 am »
Kelly Space and Technologies was working this 20 years ago.

Offline Lars-J

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #9 on: 02/04/2015 01:54 am »

I don't see the real benefit of this. You still need to make a custom carrier aircraft / drone, and now you have converted a relatively simple air launch concept into one that requires TWO stages before the rocket even is dropped (the aircraft pulling, then the carrier)

And scaling this up would be difficult - but that is a problem shared with all air launch concepts.

Gliders are a lot easier to scale, and a lot cheaper than traditional aircraft. The pulling aircraft can more likely be something that can fly in other revenue service arrangements than a dedicated air launcher. It is somewhat rube golberg, but that's not always bad.

~Jon

I don't know if a rocket propelled carrier can be classified as just a "glider". There is certainly propulsion involved, even if it doesn't activate until after the glider is disconnected.

Offline Rocket Science

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #10 on: 02/04/2015 01:54 am »
Why not place two turbofans over each fusalage and make do without the tow? But that's just me...

Oh yeah, no worries, just add a full-blown propulsion system. No biggie. :-)

~Jon
And Burt would put canards on it.... ;D
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Offline jongoff

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #11 on: 02/04/2015 03:36 am »
I don't know if a rocket propelled carrier can be classified as just a "glider". There is certainly propulsion involved, even if it doesn't activate until after the glider is disconnected.

I actually agree that putting a rocket on the carrier vehicle kind of defeats some of the benefits of having it be a glider. I'd much rather see a variant that carried a liquid fueled rocket, used its engines to provide the pitch up maneuver, and at most had some cross-feed topping tanks to keep the liquid rocket topped up until say ~1-2s before glider/stage separation. Then the glider can be kept pretty simple, the rocket gets tested out before release, and it gets released into a performance optimal trajectory that minimizes needless gravity losses.

People normally freak out about my "gamma maneuver" concept of lighting the launch vehicle's engines prior to staging, but part of the point of a glider is that it's an unmanned, relatively low cost vehicle that you can take higher (perceived) risks with.

As I said, I don't agree 100% with every design decision for this specific concept, but I don't think it's that far from something that could be interesting.

~Jon

Offline john smith 19

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #12 on: 02/04/2015 04:20 pm »
People normally freak out about my "gamma maneuver" concept of lighting the launch vehicle's engines prior to staging, but part of the point of a glider is that it's an unmanned, relatively low cost vehicle that you can take higher (perceived) risks with.
When I thought about how you'd do an intact abort on a TSTO some kind of test firing (even at partial thrust) seemed the only sensible way to test the system.

If the engines fail to light while still attached to the glider then (in principal) you get the payload back intact and the customer lives to launch another day.

I think customers like this idea.
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Offline RanulfC

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #13 on: 02/04/2015 05:01 pm »
People normally freak out about my "gamma maneuver" concept of lighting the launch vehicle's engines prior to staging, but part of the point of a glider is that it's an unmanned, relatively low cost vehicle that you can take higher (perceived) risks with.
When I thought about how you'd do an intact abort on a TSTO some kind of test firing (even at partial thrust) seemed the only sensible way to test the system.

If the engines fail to light while still attached to the glider then (in principal) you get the payload back intact and the customer lives to launch another day.

I think customers like this idea.

Presently there's no evidence that customers would "choose" such an idea (payload recovery capability) if it were offered but I can't see (assuming all else is "equal" such as payload to desired orbit/trajectory) how they (and insurance) couldn't NOT like the idea :)

My favorite 'reason' for launch assist schemes is IF they can grant you enough margin to allow fully recoverable stages at any point in the flight then you're that much futher ahead of anyone else at the moment. Imagine if you could get your payload back intact at any point in flight from LV release to orbit I'd think that would appeal very much to customers. Once they got used to the idea that it was possible and economic at any rate :)

As I recall though, (still need to see the video's as the don't work on this computer :( ) the main issue with towed glider launch is the take off abort scenerios and compatability with "normal" airports. Specifically with larger towed vehicles.

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Offline jongoff

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #14 on: 02/04/2015 08:19 pm »
People normally freak out about my "gamma maneuver" concept of lighting the launch vehicle's engines prior to staging, but part of the point of a glider is that it's an unmanned, relatively low cost vehicle that you can take higher (perceived) risks with.
When I thought about how you'd do an intact abort on a TSTO some kind of test firing (even at partial thrust) seemed the only sensible way to test the system.

If the engines fail to light while still attached to the glider then (in principal) you get the payload back intact and the customer lives to launch another day.

I think customers like this idea.

Yeah, but the carrier plane operators hate the idea. I tried putting together a DARPA ALASA proposal on this topic, but nobody wanted to do that with a manned carrier aircraft. In the end, we didn't have time to propose to both ALASA and DARPA Phoenix, so we ended up dropping the ALASA proposal.

~Jon

Offline RanulfC

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #15 on: 02/04/2015 08:29 pm »
People normally freak out about my "gamma maneuver" concept of lighting the launch vehicle's engines prior to staging, but part of the point of a glider is that it's an unmanned, relatively low cost vehicle that you can take higher (perceived) risks with.
When I thought about how you'd do an intact abort on a TSTO some kind of test firing (even at partial thrust) seemed the only sensible way to test the system.

If the engines fail to light while still attached to the glider then (in principal) you get the payload back intact and the customer lives to launch another day.

I think customers like this idea.

Yeah, but the carrier plane operators hate the idea. I tried putting together a DARPA ALASA proposal on this topic, but nobody wanted to do that with a manned carrier aircraft. In the end, we didn't have time to propose to both ALASA and DARPA Phoenix, so we ended up dropping the ALASA proposal.

TBH "I" don't think it's such a bad idea and if "I" operated a carrier AC I'd have no problems with it :)
(Which is probably WHY.... :) )

But I think the 'main' issue is probably airframe strain. Great if you design and build for it from the start, not so "hot" if you're planning on using an existing airframe which for the most part ALASA was doing among others. (And besides ALASA seemed to be hung up on top-mounted launch)

Looking at the pics of the prototype I don't see it having the structure to allow a powered gamma manuever either...

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 kch

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #16 on: 02/04/2015 08:50 pm »

I have to admit, the extreme barrel roll at 1:25 made me burst out laughing   :P

The Immelmann was a nice touch, wasn't it?  Probably the most efficient head-back-to-base maneuver, too.

http://en.wikipedia.org/wiki/Immelmann_turn#Aerobatic_maneuver

 :D

Offline jongoff

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #17 on: 02/04/2015 09:02 pm »
People normally freak out about my "gamma maneuver" concept of lighting the launch vehicle's engines prior to staging, but part of the point of a glider is that it's an unmanned, relatively low cost vehicle that you can take higher (perceived) risks with.
When I thought about how you'd do an intact abort on a TSTO some kind of test firing (even at partial thrust) seemed the only sensible way to test the system.

If the engines fail to light while still attached to the glider then (in principal) you get the payload back intact and the customer lives to launch another day.

I think customers like this idea.

Yeah, but the carrier plane operators hate the idea. I tried putting together a DARPA ALASA proposal on this topic, but nobody wanted to do that with a manned carrier aircraft. In the end, we didn't have time to propose to both ALASA and DARPA Phoenix, so we ended up dropping the ALASA proposal.

TBH "I" don't think it's such a bad idea and if "I" operated a carrier AC I'd have no problems with it :)
(Which is probably WHY.... :) )

But I think the 'main' issue is probably airframe strain. Great if you design and build for it from the start, not so "hot" if you're planning on using an existing airframe which for the most part ALASA was doing among others. (And besides ALASA seemed to be hung up on top-mounted launch)

Looking at the pics of the prototype I don't see it having the structure to allow a powered gamma manuever either...

I had some thoughts on how to solve that problem. I may be wrong, but I think you can solve it without actually increasing the loads seen on the aircraft of the aircraft-to-launch vehicle pylon, so long as the aircraft itself is capable of doing the pitchup maneuver without a payload attached.

~Jon

Offline RanulfC

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Re: Towed Glider Air-Launch System (TGALS)
« Reply #18 on: 02/04/2015 11:46 pm »
Why not place two turbofans over each fusalage and make do without the tow? But that's just me...

Oh yeah, no worries, just add a full-blown propulsion system. No biggie. :-)

Finally got the video to run... NOTE: It DOES have a propulsion system. The glider has its own rocket to push it through the gamma maneuver... Reading through some of the older articles available I'm guessing the LV is an all solid booster so that may be why it isn't lit up on the carrier.

I had some thoughts on how to solve that problem. I may be wrong, but I think you can solve it without actually increasing the loads seen on the aircraft of the aircraft-to-launch vehicle pylon, so long as the aircraft itself is capable of doing the pitchup maneuver without a payload attached.

From what I'm seeing it looks capable so probably not an issue even with the scale model. Still would prefer a box-wing though :)

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

Offline SteveKelsey

Re: Towed Glider Air-Launch System (TGALS)
« Reply #19 on: 02/11/2015 04:52 pm »
http://www.parabolicarc.com/2014/11/16/towed-twinfuselage-glider-launch-system-test-flight-successful/

Thought this might be useful. I like the use of a drone as the tow plane.
« Last Edit: 02/11/2015 04:54 pm by SteveKelsey »
2001 is running a little late, but we are getting there.

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