Stratolaunch: General Company and Development Updates and Discussions

[gin455res]

Does anyone know if the stratolaunch carrier would be capable of a high alpha launch that might reduce the bending moments and enable a scaled up version of the late Len Cormier's spacevan concept?

This, if I inferred correctly, by releasing the winged orbiter at a really high angle of attack in a climb, meant the wing was only scaled for landing weight and the were no pitch up bending moments on the tank/fuselage to crap out your mass fraction. 

[Is the spacevan concept somewhat like a cross between an altitude-optimised hybrid between a ramp-launch and a VTHL (vertical take-off horizontal landing) system?]

And are we sure there are no inspired systems engineering combinations that couldn't make air-launch feasible, I feel we are throwing in the towel far too easily, and soon, without fully exploring the huge '(possible?) solution space'.

What about Gary Hudson's VALS concept?

http://forum.nasaspaceflight.com/index.php?topic=36709.msg1344145#msg1344145

The predecessor to Roc had rocket engines to provide a gamma turn, but it certainly appears that Roc lacks them (probably a wise decision as they were SS2 hybrids...).

Gary, given access to an existing carrier aircraft a) with a safe rocket that enabled a gamma turn, or b) a standard aircraft; which would you choose?; and have you modeled any launch systems with type a) ?

I wouldn't use VALS since Roc can already carry a huge payload of 500K lbm.  VALS was an attempt to allow an off-the-shelf a/c to carry more than its current nominal payload (i.e., >200K lbm for a 747-200). It was also meant to eliminate the diameter constraint (i.e., about 85 inch dia limit for belly carriage on the 747).

In the VALS paper you list one of the advantages of the concept as the safety to the carrier aircraft that the large distance between the rocket and the a/c that the tow/cable offers.  Presumably, this safety is traded for the simplicity of t-LAD? and would you care to elaborate on the differences in the bending moments experienced by the VALS rocket at the transition from where it hangs below the aircraft and where the rocket-carrier switches to high drag mode and swings? up and behind the carrier plane; and those experienced by the t-LAD release? (that would be interesting!)

I would simply use a t/LAD approach and eliminate any LV wings altogether.  It's pretty straightforward.  AirLaunch offered it to SL on a couple of occasions but they ignored the option.

I was saddened when air-launch didn't get the opportunity to continue with testing out this approach, you seemed to be progressing steadily and the concept seemed nice in the way it simplified all the constituent components. And it appeared to be one of the lowest hanging fruit of many of the potential systems I'd read about (in terms of resources needed to test). Were there any upcoming technical issues in the test program that potential funders or investors were concerned about?   

[Zed_Noir]

If the LV suffers a RUD on pad or just above the pad, it tends not to be hugely catastrophic. Any damaged/contaminated/incinerated ground infrastructure is comparatively simplistic (and cheaper) to fix up.

If the LV blows itself to pieces attached to the Roc or in the immediate area of the Roc post separation, you are going to lose the plane, along with the crew. The potential for people to die goes up significantly.

So the North American X-15 series of spaceplanes should not have been flown from the B-52 carrier aircraft according to your reasoning?

Apples and oranges there. X-15 was small compared to B-52, had only about 50% propellant load and was an experiment to do groundbraking research. The smaller size and prop load meant less danger for carrier plane than near 1:1 payload with >90% propellants and objective enabled higher risk.

Carrying commercial orbital LV for routine flights is a whole new ball game.

IRRC the X-15 propulsion system is not lit until it separate by a few hundred feet from the B-52 after being drop. Which I presume is how Stratolaunch was planning to do. So in both caes the carrier aircraft have a chance of outrunning the blast from a severe RUD event during engine startup.

However if the propulsion system goes kaboom while the X-15 is attached to the B-52 or some LV is attached to the Roc than I don't expect either carrier aircraft to survive. After all the B-52 fuel tanks are in the wings. According to the scenario from @The Amazing Catstronaut.

But you are correct, it is apples & oranges in the degree of risk.

[Kabloona]

Air launch has always seemed like a terrible idea.

Tell that to Antonio Elias, a pretty brilliant guy who thought up Pegasus. It didn't "always seem like a terrible idea" to him, nor to Orbital or the many people who have done 40+ successful and profitable Pegasus launches.

Sure wings can help with that but at some point you get diminishing returns and if you throw that weight of wings and extra structure towards fuel instead, you might as well just go from the ground and have one less "stage". In my mind, the other obvious cons like no hold down testing and safety of carrying what equates to a giant pressure vessel quickly outweigh any pros.

After having defended Pegasus as a not-so-terrible idea, I do believe Antonio himself has conceded, IIRC, that the weight of the Pegasus wing more or less cancels out the performance gained by air launching, so it turns out to be a wash performance-wise. And you can't do hold-down tests anyway on solids, so that point is irrelevant for Pegasus.

Obviously scaling up the concept for Stratolaunch is different ball of wax, but it's inaccurate to make a blanket statement about all air launched systems being "terrible" ideas. If Pegasus was such a terrible idea it wouldn't still be flying.

[The Amazing Catstronaut]

...

So the North American X-15 series of spaceplanes should not have been flown from the B-52 carrier aircraft according to your reasoning?

Yes, essentially. I'd like to think we can have rockets which are safer than their late 1950s/1960s counterparts half a century on. Besides, I believe that a dedicated multistage commercial launch vehicle should have higher safety margins than a hypersonic research aircraft, or at least equivalent to (she did have a good term of service). I'm not denying that the X-15 was a great little suborbital space plane, but this is a lot more than an X-15 and could make or break interest in air launching if any of the circumstances I've listed above occur.

It's more likely economics will kill Stratolaunch however, sadly. I'm optimistic right now though.

[HMXHMX]

Does anyone know if the stratolaunch carrier would be capable of a high alpha launch that might reduce the bending moments and enable a scaled up version of the late Len Cormier's spacevan concept?

This, if I inferred correctly, by releasing the winged orbiter at a really high angle of attack in a climb, meant the wing was only scaled for landing weight and the were no pitch up bending moments on the tank/fuselage to crap out your mass fraction. 

[Is the spacevan concept somewhat like a cross between an altitude-optimised hybrid between a ramp-launch and a VTHL (vertical take-off horizontal landing) system?]

And are we sure there are no inspired systems engineering combinations that couldn't make air-launch feasible, I feel we are throwing in the towel far too easily, and soon, without fully exploring the huge '(possible?) solution space'.

What about Gary Hudson's VALS concept?

http://forum.nasaspaceflight.com/index.php?topic=36709.msg1344145#msg1344145

The predecessor to Roc had rocket engines to provide a gamma turn, but it certainly appears that Roc lacks them (probably a wise decision as they were SS2 hybrids...).

Gary, given access to an existing carrier aircraft a) with a safe rocket that enabled a gamma turn, or b) a standard aircraft; which would you choose?; and have you modeled any launch systems with type a) ?

I wouldn't use VALS since Roc can already carry a huge payload of 500K lbm.  VALS was an attempt to allow an off-the-shelf a/c to carry more than its current nominal payload (i.e., >200K lbm for a 747-200). It was also meant to eliminate the diameter constraint (i.e., about 85 inch dia limit for belly carriage on the 747).

In the VALS paper you list one of the advantages of the concept as the safety to the carrier aircraft that the large distance between the rocket and the a/c that the tow/cable offers.  Presumably, this safety is traded for the simplicity of t-LAD? and would you care to elaborate on the differences in the bending moments experienced by the VALS rocket at the transition from where it hangs below the aircraft and where the rocket-carrier switches to high drag mode and swings? up and behind the carrier plane; and those experienced by the t-LAD release? (that would be interesting!)

I would simply use a t/LAD approach and eliminate any LV wings altogether.  It's pretty straightforward.  AirLaunch offered it to SL on a couple of occasions but they ignored the option.

I was saddened when air-launch didn't get the opportunity to continue with testing out this approach, you seemed to be progressing steadily and the concept seemed nice in the way it simplified all the constituent components. And it appeared to be one of the lowest hanging fruit of many of the potential systems I'd read about (in terms of resources needed to test). Were there any upcoming technical issues in the test program that potential funders or investors were concerned about?   

I don't want to take the SL thread off-topic, but I'll just note that Burt was the guy who liked gamma turns; I didn't.  Straight and level is my preferred way of deploying at altitude. 

As for AirLaunch's efforts, the battle wasn't over technology but politics.  Our program ran afoul of certain USAF hypersonics interests who saw it as a threat to their programs, and had us killed.  Nothing more complicated than that.  SL has the advantage that they are privately funded, so are essentially immune to political pressure. 

[R7]

If Pegasus was such a terrible idea it wouldn't still be flying.

No offence towards Orbital but Pegasus is still flying (very rarely!) only because there aren't any good options (from the customers perspective)  in that payload class. Even F9_r may be a better choice in the future to fly your half ton sats...

http://innerspace.net/current-launch-vehicles/pegasus-launch-cost-soars-to-55-million/

[Kabloona]

If Pegasus was such a terrible idea it wouldn't still be flying.

No offence towards Orbital but Pegasus is still flying (very rarely!) only because there aren't any good options (from the customers perspective)  in that payload class. Even F9_r may be a better choice in the future to fly your half ton sats...

http://innerspace.net/current-launch-vehicles/pegasus-launch-cost-soars-to-55-million/

Yes, Pegasus is suffering from marginal economics and a death spiral of fewer launches making each launch more costly for Orbital. That doesn't mean air launch is "always a terrible idea" as claimed upthread. Pegasus filled a market niche and put a lot of payloads in orbit for less cost than the alternatives at the time.

However, its marginal business case, and moreover the serious problem of scaling up, should have served as a warning to Stratolaunch. The lessons and wisdom from Pegasus were there to be learned, and they apparently weren't.

[Rocket Science]

If the LV suffers a RUD on pad or just above the pad, it tends not to be hugely catastrophic. Any damaged/contaminated/incinerated ground infrastructure is comparatively simplistic (and cheaper) to fix up.

If the LV blows itself to pieces attached to the Roc or in the immediate area of the Roc post separation, you are going to lose the plane, along with the crew. The potential for people to die goes up significantly.

So the North American X-15 series of spaceplanes should not have been flown from the B-52 carrier aircraft according to your reasoning?

Apples and oranges there. X-15 was small compared to B-52, had only about 50% propellant load and was an experiment to do groundbraking research. The smaller size and prop load meant less danger for carrier plane than near 1:1 payload with >90% propellants and objective enabled higher risk.

Carrying commercial orbital LV for routine flights is a whole new ball game.

IRRC the X-15 propulsion system is not lit until it separate by a few hundred feet from the B-52 after being drop. Which I presume is how Stratolaunch was planning to do. So in both caes the carrier aircraft have a chance of outrunning the blast from a severe RUD event during engine startup.

However if the propulsion system goes kaboom while the X-15 is attached to the B-52 or some LV is attached to the Roc than I don't expect either carrier aircraft to survive. After all the B-52 fuel tanks are in the wings. According to the scenario from @The Amazing Catstronaut.

But you are correct, it is apples & oranges in the degree of risk.

The XLR-99 engine was ignited and set to idle before drop. It could only do so for 30 seconds so you had to drop and light off the main chamber or shut down.

[sghill]

I don't know anything about their inside operational economics, but it seems to me that their [anticipated] secret sauce simply has to be the operational costs of the carrier aircraft and ground operations.  If they can get those two costs down while having a high operational tempo, then they can still make money. 

They aren't dumb, but perhaps the market they wanted to capture may be addressed by other operators and the launcher difficulties they're having are exacerbating this issue for them.  Going back to the different launcher designs- and the different economics of each- may be how they are addressing the shifting sands of a market for their unique capability.  They've got to, as they said, "hit a sweet spot."  I happen to think the sweet spot moved adversely on them and they know this. 

[RanulfC]

The XLR-99 engine was ignited and set to idle before drop. It could only do so for 30 seconds so you had to drop and light off the main chamber or shut down.

As I understand it what was "ignited" was the torch igniter for the engine. Since it couldn't be throttled down lower than 50% actually igniting the engine on the pylon would have been problematical at best. If the engine failed to ignite after drop the procedure was to dump propellant and glide to the abort landing site.

I don't know anything about their inside operational economics, but it seems to me that their [anticipated] secret sauce simply has to be the operational costs of the carrier aircraft and ground operations.  If they can get those two costs down while having a high operational tempo, then they can still make money. 

They aren't dumb, but perhaps the market they wanted to capture may be addressed by other operators and the launcher difficulties they're having are exacerbating this issue for them.  Going back to the different launcher designs- and the different economics of each- may be how they are addressing the shifting sands of a market for their unique capability.  They've got to, as they said, "hit a sweet spot."  I happen to think the sweet spot moved adversely on them and they know this. 

As I understand it the three main factors for air launch are:
1) Speed
2) Altitude
3) AoA to local horizon (gamma)

Most air launch concepts ONLY get #2 and at around 30-40,000ft that's not much. t/LAD allowed #3 as well but no one seems interested. (Number 1 is just hard to do with an operationally economic aircraft capable of carrying a sizable LV)

Advantages are supposed to be lower operating costs of the air breathing first stage and launch azimuth due to ability of the carrier AC to move the "launch site" to meet required orbital plane.

Frankly my take is doing this with a dedicated, custom built carrier AC and large LV is not going to hit any of the suggested goals and they would have been better giving in and taking Gary's suggestion
(I'd argue the "simplicity" of the VPak over a more efficient rocket but... )

Technically (and this IS OT) I'd have suggested going with a lower payload per flight and doing VTOL with a jet-LAP (Launch Assist Platform) and tried to get some of all three factors over the orbital plane advantage. But that's probably just me

Randy

[RanulfC]

Gary, given access to an existing carrier aircraft a) with a safe rocket that enabled a gamma turn, or b) a standard aircraft; which would you choose?; and have you modeled any launch systems with type a) ?

You might check out the "ALTO/Crossbow" launch concept which I can't access from this computer. (Use that as a keyword) It suggested a "custom-built" airframe but a very minimalist one that flew back to the launch site autonomously. The LV stayed attached after engine start and was used to push the assembly into a high gamma before release.

You still have to build a pretty robust LV but it you're going to make it reusable anyway...

Stick a DreamChaser on the end and you could run the entire flight from the cockpit. I really like that idea

Randy

[adrianwyard]

I've not been following this too closely, but doesn't stratolaunch (and air launch in general) also have properties that are appealing to the military? Namely, the carrier aircraft is a highly available 'range' that's not subject to weather constraints and can be based at/launch from somewhere other than FL, CA, etc.

If so, then Paul Allen may yet find a customer - assuming this wasn't an unstated possibility from the beginning.

I've often wondered how robust ICBMs are in terms of bad weather. Given how often commercial launch providers scrub due to winds/lightning et al it seems some percentage of the old liquid fueled ICBMs might have run in to trouble uphill if they had to launch in dodgy weather; a worrying thought! But if the military's current solid fueled rockets can already launch through bad weather, then that diminishes the case for stratolaunch I made above.

[Kabloona]

I happen to think the sweet spot moved adversely on them and they know this.

With SpaceX already offering dual manifest launches at $35 million or so, and on the verge of offering reflights of F9 stage 1 at possibly much less than $60 million, the handwriting is on the wall.

[RanulfC]

I've not been following this too closely, but doesn't stratolaunch (and air launch in general) also have properties that are appealing to the military? Namely, the carrier aircraft is a highly available 'range' that's not subject to weather constraints and can be based at/launch from somewhere other than FL, CA, etc.

Less weather, more availability of "on-demand-to-interesting-orbits" capability but the SL launcher and more importantly LV is to "heavy" for military use. They would want small-sats not the big dedicated birds.

If so, then Paul Allen may yet find a customer - assuming this wasn't an unstated possibility from the beginning.

I noted earlier that given a really robust pylon the ability to carry large modular loads "might" be militarily interesting but I doubt it was Alan's first idea

I've often wondered how robust ICBMs are in terms of bad weather. Given how often commercial launch providers scrub due to winds/lightning et al it seems some percentage of the old liquid fueled ICBMs might have run in to trouble uphill if they had to launch in dodgy weather; a worrying thought! But if the military's current solid fueled rockets can already launch through bad weather, then that diminishes the case for stratolaunch I made above.

The earliest Atlas' and IRBMs were a bit difficult but the KEY idea was you were launching to end the world so a little "weather" was disregarded and designed around.

Air Launched ICBMs were in fact greatly discussed, studied and eventually discarded as to operationally cumbersome for use. The military DOES in fact "air-launch" a lot. Most of the test missiles for missile defense and early-warning/tracking purposes are simple one or two stage vehicles dumped out of the back of a C-130 and lit off. You really don't need that much performance for a sub-orbital dummy warhead for test purposes.

I happen to think the sweet spot moved adversely on them and they know this.

With SpaceX already offering dual manifest launches at $35 million or so, and on the verge of offering reflights of F9 stage 1 at possibly much less than $60 million, the handwriting is on the wall.

As noted everywhere else this is brought up "dual-manifesting" isn't new nor is it really as much of an advantage as people make it out to be. Most satellites simply don't need or want to go to the same orbit.

The article notes that SL may actually be rethinking their approach and one of the supposed main "advantages" of air-launch is to allow enough margin to include reusability and I think that's the main reason that SL is stepping back from LV development. None of their previous designs even considered the idea and it IS a key to lowering costs.

Any LV design is going to have to be fully reusable and this is going to effect the payload-to-orbit point. I think Alan didn't fully appreciate how air launch works and what it could do and that's going through a change right now. I still think they could do something with the basic start they have, (sunk costs isn't necessarily a fallacy in this case) but they are going to have to think long and hard and look outside the "box" they have been in since they laid down the concept to make this work.

Randy

[RanulfC]

I happen to think the sweet spot moved adversely on them and they know this.

With SpaceX already offering dual manifest launches at $35 million or so, and on the verge of offering reflights of F9 stage 1 at possibly much less than $60 million, the handwriting is on the wall.

Oh and I might as well say it; SpaceX has to both recovery and be ABLE to refly before they can offer it and we really shouldn't get to far ahead of ourselves even if we're fans

Randy

[jongoff]

Air launch has always seemed like a terrible idea. The first issue is that while you get a bit of starting height, you are working with a negative vertical velocity that you have to overcome right from the get go after being dropped. Sure wings can help with that but at some point you get diminishing returns and if you throw that weight of wings and extra structure towards fuel instead, you might as well just go from the ground and have one less "stage". In my mind, the other obvious cons like no hold down testing and safety of carrying what equates to a giant pressure vessel quickly outweigh any pros.

Good point about the lack of hold down test. In vertical launch if an engine doesn't fire or problem is detected in hold down the launch is aborted, nothing is lost but time. For air launch once LV is deployed it's engines better perform.

This is why I think the main benefits of air launch only come if you bite the bullet and learn how to (safely/reliably) do the gamma maneuver. That's where you light the rocket (throttled way-back) while attached to the aircraft, and use the added thrust to pull up into a good flight-path angle prior to separation. If you are smart enough to do some cross-feed from the aircraft, you get all the benefits of ground hold-down firings, you don't have a pad that needs refurbishing every flight, you avoid the drop and light gravity losses (which can easily be 100s of m/s worth of air launch benefit flushed down the tubes).

It's just scary as heck and needs some serious subscale prototyping before you could apply it to a full-scale vehicle... :-)

~Jon

[Robotbeat]

You could always do it unmanned/unma'ammed.

[matthewkantar]

I would think if you were going to attempt to start the engines while still attached to the carrier aircraft, it would be wise to spend a bit more money to develop an unmanned vehicle. No need to imperil any lives in this age of computer and automation wizardry. If the Soviets flew and remote landed Buran in 1988, an uncrewed carrier craft should be a breeze.

Enjoy, Matthew 

edit, R.B. beat me to it.

[TrevorMonty]

Even if unmanned the SL is still at risk, blow that up and they are out of business for a very long time.

[wannamoonbase]

It was/is a good idea. 

When they started they couldn't have seen how SpaceX was going to rewrite the pricing structure of the industry.  Plus SpaceX could gobble up much of the market with 4 launch pads and reusable rockets.

   It won't leave much for other players.