Stratolaunch: General Company and Development Updates and Discussions

[hop]

3/ Vacuum optimised engines not as good for vertical powered landing.

Wild thought: if you have wings on the first stage anyway, maybe you land it on a runway ?  OK, probably won't work given the very different flight regimes, but if there is a tricky way to make work, Rutan would be the guy to do it.

[alk3997]

I've got a few operational questions...

1) How does the payload / crew get into the Dragon?  If it's payload I guess it gets loaded in the hanger.  But, for people that would mean the crew is loaded before the booster is fueled, since propellant loading would have to take place outside the hanger.  So how is this done?

2) How do you dump prop without affecting the flying capabilities of the turbofans?  Nothing like dumping a bunch of liquid oxygen to change the mixture ratio.  I'll have to go back and look at how Pegasus does this.

Andy

[DaveS]

2) How do you dump prop without affecting the flying capabilities of the turbofans?  Nothing like dumping a bunch of liquid oxygen to change the mixture ratio.  I'll have to go back and look at how Pegasus does this.

Andy

Pegasus is all-solid, there's nothing to dump in the event of a scrub.

[jongoff]

As long as the total width of the landing gears fits on the runway, it should work. It's like an A3 Sky Warrior or an A5 Vigilante catapulting off a carrier.

You do need margin for steering and landing inaccuracies, and you have to make sure there aren't things off the runway to clip.

Runways are cheap compared to aircraft, launch vehicles and spacecraft. Especially out west, where geology has just about built them for you! How many takeoff/landing site would it need?

Sure but you are going to need FAA clearance to launch this over land.  Are they going to get that when they are essentially carrying a huge bomb?

Quite possibly, because there are plenty of ways of mitigating those risks...remember people have been studying this general concept for decades.  It's not like you're the first one to think of most of these concerns.

~Jon

[jimvela]

Maybe SpaceX is happy for more F5 work, especially with the upgraded merlins, and this is a good way for someone else to pay for it?

There's an interesting question here. The statement in the press conference was that this wouldn't compete with F9, because it was a smaller payload class. Much was made of capturing the Delta II class market. Now, if SpaceX thought there was a big market there, they could just build Falcon 5. So the answer seems to be they didn't think it was worth doing on their own dime, or don't have the cash to try.

Once upon a time, I had the insane idea that an interesting F9 configuration would be to strap on a couple of F5 sized boosters using the  9-engine thrust structure and use them as boosters.  It almost made sense if the boosters could fly back.

I discounted it in part because a winged F5 with flyback capability just seemed like too much complexity and too much work.  I was also pretty sure that with all the other things SpaceX was doing, there wasn't any money around to fund such a crazy idea.

It doesn't sound so crazy to me any more... So aside from building a F5 booster, I can see where SpaceX could benefit from the development activities associated with this activity.

I'm not at all convinced this stratolaunch concept is a practical thing, but I for one would sure like to see one fly someday.

Edit: Plus, if SpaceX ever wanted to license one of Rutan's novel swivel-wing recovery methods for a booster (hint, hint)- this would be a good way to end up with such a license...

[jongoff]

What a shame Rutan, Griffin, Musk and Allen didn't consult with the members of this forum first before embarrassing themselves with this proposal.

:-)

You beat me to the punch.

~Jon

[MP99]

- The nose of the aircraft is visually similar to a 747. Since the rest of the fuselage has nothing in common with a 747 (most importantly the high-mounted wing), I can think of no practical reason for this. The 747's hump was created to accommodate the nose door on the freighter version.

 - The current Falcon does not have to deal with horizontal gravity loads while fueled. Significant structural modification would be expected.

Could that hump be there because the two fuselages contain large fuel tanks? I'm wondering if the Falcon is empty (bu pressurised) when it takes off, then is fuelled up at altitude.

I'm assuming that loads on the Falcon would be greatest at takeoff, and that would reduce stresses? Sounds pretty hairy, though.



This whole thing does seem rather weird to me. A group of people are going to get into a Dragon, then spend a nervous couple of hours strapped on their backs while the plane takes off and manoeuvres towards launch?

As Jim says, those Merlins had better light first time.

It seems to trade four Merlins for a reduced payload and having to maintain a big plane, and Falcon doesn't seem to have the recovery hardware that I'd have expected. Perhaps because it's too heavy. Max payload of the plane is less than half that of F9 (about the same in pounds instead of kg).

But, with recovery hardware, it would seem to be a candidate for Jon Goff's http://selenianboondocks.com/2008/09/orbital-access-methodologies-part-vi-air-launched-glideforward-tsto/.

cheers, Martin

Edit: and I'm sure Glynn Shotwell said that they'd looked at an F5 with M1D (nearly same thrust as 9x M1C) but it had some controllability issues.

Edit 2: Looks like RobLynn beat me to most of this.

[jongoff]

You'd be adding another half million pounds of thrust to an aircraft designed to take 2/3 that. That would also exert a very large torque about a single point on the wings, risk the aircraft taking debris from any engine failures, and have to deal with the plume.

And all of those are ones that can be mitigated easily if designed in from the start.  As a bonus, doing such a rocket assisted zoom climb (or gamma maneuver) saves you a lot of delta-V in gravity losses, eliminates the need for the Pegasus wing, and reduces the bending moments on the rocket stages allowing you to have lighter structures.

Plus the whole making sure you don't drop a fully-loaded rocket till you know its engines are working properly.

There *are* definitely engineering considerations, but Kirk Sorensen sold me years ago on this approach making a lot of sense.  Compared to a wingless drop-and-light approach you're talking about as much as a 500m/s reduction in delta-V to orbit.

~Jon

[Rocket Science]

I’m sorry if I can’t get too excited by all this. Unless a system becomes simple and fully reusable, I just can’t grasp the point of the concept yet. I need more time to think on it a bit…

[jimvela]

And all of those are ones that can be mitigated easily if designed in from the start. 

The pilot would need some serious stones to be willing to have a burning F5 go zinging by the cockpit at close range and high airspeed. 

Way big stones.

Kelly Johnson and company had nightmares with separating (from above) a smaller vehicle from a larger one at supersonic speeds. 

I'd imagine similar problems with that in a rocket-powered zoom climb configuration of this thing.

[iamlucky13]

This proposal is either insane or brilliant.  I'm betting on insane, but hey I'm not going to tell Paul Allen how to invest his money.

Yes, it's his right to decide how to spend the money, but that doesn't mean the rest of us have to forfeit our opinions on how best to spend it. I've got plenty of opinions myself, but for now I'm just a little awestruck at the ambition he's displaying (perhaps naively).

I just decided I don't care if it's a good concept or not. I want to see that plane fly!

I have to agree with your sentiments there. I'd be thrilled to see it fly, even if I don't think he can make money with it.

- Ed Kyle had an astute point about fuel and landing in case of a post-takeoff abort. Maximum landing weights are typically substantially less than maximum takeoff weights.

How about dumping the liquid oxygen if an abort is required? Liquid oxygen is one of the most environmentally friendly things to dump there is!

That is potentially feasible, although dumping only one fuel screws with your center of gravity. Landing weight is a complication, not a showstopper.

- An-225 has about a 2500 mile range with a 550,000 pound payload. A 1300 mile radius in a twin fuselage aircraft with additional equipment for fuel topoff and drop sounds ambitious.

Boeing's 747-100 had a range of 5300 nm in the 1960s. Burt Rutan has successfully designed and built two different three-fuselage aircraft with 26,000 mile range: http://en.wikipedia.org/wiki/Rutan_Voyager and http://en.wikipedia.org/wiki/Virgin_Atlantic_GlobalFlyer .  I don't understand why you expect a measly range of 2600 miles to challenge Rutan.

Global Flyer was only 17% airplane and payload by weight, and the payload was almost nothing. The rest was fuel. It was very structurally efficient, but not very versatile.

Aircraft often trade payload for fuel. It's not terribly uncommon for airliners flying longer routes to have to bump passengers when a headwind is expected (or divert if one comes up unexpectedly).

Stratolauncher doesn't have that luxury. They have a more or less fixed half-million pound payload.

If the carrier aircraft comes in overweight as design progresses, they have little recourse but to reduce the range.

If you assume Scaled can achieve an empty weight comparable to the An-225, add on the weight of the rocket, then a 1.2 million pound MTOW leaves you 82,000 pounds for fuel - about 1/4 what the 747-100 could carry.

Flying half the distance on 1/4 the fuel in a much larger plane with 50% more engines sounds questionable. It seems almost certain they plan to build a lighter plane than the An-225.

That's where my skepticism comes in. Scaled is great at building light aircraft, and this one is helped by not needing most of the fuselage volume pressurized, but they have two fuselages to carry, a bigger wing with a very beefy center section, and a collection of launch support equipment. They also don't have hundreds of planes to amortize development cost over to make lots of weight optimizing feasible.

[jongoff]

Advantages:
1/ Pick your orbital inclination.
2/ Save 4-500m/s deltaV
3/ Use vacuum optimised engines with 20-30s higher ISP
4/ Can cruise to up-range launch point to allow easier recovery of booster stages (no boost-back)
5/ Fewer issues with range safety, noise and NIMBYs

Glad you saw #4.  Here's a few more:

1-You can actually save as much as 1000m/s of losses by air-launching so long as you release in a good flight path angle (zoom climb or rocket-assisted zoom climb)
2-For manned launches, launch escape is easier, especially if you have one of the propellants (probably the Kero) stored on the airplane until a few minutes before the launch.  Max Q is tons lower, and the "pad abort" type scenario is also easier.
3-Much easier to do first-orbit rendezvous for space facilities, which matters a lot for manned flight and higher ops tempos.
4-Makes it easier to ferry a rocket from the factory to the launch site...no need for trains, trucks, or barges.

Downsides:
1/ lateral fully fuelled g-loading will probably require heavier LV structure.
2/ Big expensive plane to develop and maintain.
3/ Vacuum optimised engines not as good for vertical powered landing.
4/ Potentially huge torsional loads on center wing without a secondary bridging connection at the tail.

Guesses:
1/ Launch LV empty and fuel in-flight to improve safety and reduce lateral stresses on LV and other components as well as perhaps reducing need for LV tank insulation.
2/ Start rockets before release for safety checkout and then while continuing to refuel, use rocket power to enable swoop upwards and acceleration up to near Mach 1 at maximum atltiude

While they didn't appear to be baselining either of those options, I agree that rocket assisted zoom climb to get a good flight path angle (and check out the engines) is a great idea, and having at least one of the propellants stored on the airplane and transferred right before launch is also a good idea. 

~Jon

[Dappa]

- The nose of the aircraft is visually similar to a 747. Since the rest of the fuselage has nothing in common with a 747 (most importantly the high-mounted wing), I can think of no practical reason for this. The 747's hump was created to accommodate the nose door on the freighter version.

Could that hump be there because the two fuselages contain large fuel tanks? I'm wondering if the Falcon is empty (bu pressurized) when it takes off, then is fueled up at altitude.

Or could it be because you don't want to have the rocket next to the cockpit? I can imagine that a pilot wants to look over the payload fairing, not have his view blocked by it.

[jongoff]

And all of those are ones that can be mitigated easily if designed in from the start. 

The pilot would need some serious stones to be willing to have a burning F5 go zinging by the cockpit at close range and high airspeed. 

Way big stones.

Kelly Johnson and company had nightmares with separating (from above) a smaller vehicle from a larger one at supersonic speeds. 

I'd imagine similar problems with that in a rocket-powered zoom climb configuration of this thing.

You wouldn't separate at supersonic speeds.  You're just using the airplane's wings to bend the velocity vector upwards before separation.  This is something you could totally prove-out thoroughly in subscale.

The idea of mid-air refueling of aircraft used to be considered scary too.

:-)

~Jon

[Namechange User]

I'm slightly annoyed by some of the comments on this thread.

So many yesterday (on the thread that has disappeared) were going on and on, basically SpaceX-gushing, about how great today would be and my comments on that thread were seemingly on point.

Now, with this thread, too many are dismissing it without knowning anything about it in reality (nor likely qualified to speak about it).  You want commercial?  This is commercial, not a dime to be taken from the government, but instead someone trying to do something with private capital.  That is outstanding news but instead it is meeting with grumbling. 

Also, here is Paul Allen, Burt Rutan, Mike Griffin, etc standing shoulder-to-shoulder discussing a very unique concept, which invalidates the arm-wavers running around always spewing Griffin-Hate.  It's stupid and childish (and the same goes for that other website) and personally, I believe, why the "space community" is not taken seriously. 

[Chris Bergin]

Cool... this even got picked up by local news outlets...

ex: http://www.wral.com/news/science/story/10495959/

But oddly, not by nasaspaceflight.com. Yet.

1) The local news didn't pick it up. They just selected what AP articles they'd paste into their site. It even says AP in the byline.

2) We technically already did with this thread. No interest in rehashing the press release, available in this thread. And hopefully we'll have a more interesting article via Isaac soon, per arrangement.

[lorahpj]

Advantages:
1/ Pick your orbital inclination.
2/ Save 4-500m/s deltaV
3/ Use vacuum optimised engines with 20-30s higher ISP
4/ Can cruise to up-range launch point to allow easier recovery of booster stages (no boost-back)
5/ Fewer issues with range safety, noise and NIMBYs

Downsides:
1/ lateral fully fuelled g-loading will probably require heavier LV structure.
2/ Big expensive plane to develop and maintain.
3/ Vacuum optimised engines not as good for vertical powered landing.
4/ Potentially huge torsional loads on center wing without a secondary bridging connection at the tail.

Guesses:
1/ Launch LV empty and fuel in-flight to improve safety and reduce lateral stresses on LV and other components as well as perhaps reducing need for LV tank insulation.
2/ Start rockets before release for safety checkout and then while continuing to refuel, use rocket power to enable swoop upwards and acceleration up to near Mach 1 at maximum atltiude

I wonder if the advantages are enough.

I have always thought a Gryphon style launch concept (similar to some of the 70's Shuttle proposals) would be a huge breakthrough and a more natural follow-on to SpaceShipTwo - the 1st stage aircraft would take a SpaceShipOne/Two style flight trajectory (fully reusable and quickly turned around) and would loft a 2nd stage rocket with payload.

A Gryphon style carrier could also be used for dedicated suborbital flights - a variant without payload carrying capability could haul a lot of passengers (space tourists) on suborbital ballistic flights cheaply.  Now whether there is enough demand, is a completely separate question.
http://www.andrews-space.com/content-main.php?subsection=MTA4

[HammerD]

This proposal is either insane or brilliant.  I'm betting on insane, but hey I'm not going to tell Paul Allen how to invest his money.  My hope here is that, if this isn't successful, that new technologies are developed that make spaceflight cheaper and more reliable.  It would be a step towards reusability.  This is all going to be pure wait-and-see for the next 5 years.

I applaud the efforts but if I had the cash I would have spent it on developing a lander or a spacecraft like the Nautilus X or some other craft to get us beyond LEO, or they could have announced a program to return to the moon using Falcon 9 or Falcon 9 Heavy.

I think there are enough commercial satellite launchers either already available or in development.

I also think this is will turn out to be very expensive way of launching (more expensive than a Falcon 9 with less capability)....just IMHO.

Wish them the best but disappointed in what was announced.

[Jim]

Why does everybody talk about recovery?  They explicitly say they are not doing it.

[jongoff]

I'm slightly annoyed by some of the comments on this thread.

So many yesterday (on the thread that has disappeared) were going on and on, basically SpaceX-gushing, about how great today would be and my comments on that thread were seemingly on point.

Now, with this thread, too many are dismissing it without knowning anything about it in reality (nor likely qualified to speak about it).  You want commercial?  This is commercial, not a dime to be taken from the government, but instead someone trying to do something with private capital.  That is outstanding news but instead it is meeting with grumbling. 

Also, here is Paul Allen, Burt Rutan, Mike Griffin, etc standing shoulder-to-shoulder discussing a very unique concept, which invalidates the arm-wavers running around always spewing Griffin-Hate.  It's stupid and childish (and the same goes for that other website) and personally, I believe, why the "space community" is not taken seriously. 

Yeah, I have to agree that it's always impressive as hell to see someone like Mr Allen with the balls to put several hundred $M on the line for something that people are so ready to nay-say.  I think they've got a technical approach that while not identical to what I've been looking at over the years, is still perfectly workable (and definitely lower development risk).  I think they've got a good shot to make a real difference here, and am looking forward to seeing more details coming out.

I'm also looking forward to seeing posts 5-7yrs from now by people currently nay-saying the idea claiming that they always knew it would work.

~Jon