Stratolaunch: General Company and Development Updates and Discussions

[edkyle99]

They're evaluating different launch vehicles. I take them at their word.

I don't doubt that air-launch was the original intention of this project, but I doubt that it will be the ultimate result.  It seems obvious that specialized heavy air-lift (either cargo or as the mother of "mother-ships") is the only alternative.   

 - Ed Kyle

[starchasercowboy]

ROC started out as an Air Force project through Scaled Composites/BAE systems called LOFTY.  Burt probably sold the idea to Paul after the WK1 SS1 success.

[baldusi]

They're evaluating different launch vehicles. I take them at their word.

I don't doubt that air-launch was the original intention of this project, but I doubt that it will be the ultimate result.  It seems obvious that specialized heavy air-lift (either cargo or as the mother of "mother-ships") is the only alternative.   

 - Ed Kyle

They don't have a transport pod, and the aircraft clearance is actually limited. The only reason military airlift uses wings on top is reduce the risk of FOD on "dirty" airstrips. I don't know if Roc conserves that feature. If you were looking for maximum internal diameter, wings on the bottom are better (like Beluga, Guppy and Dreamlifter have done). And simplicity of loading/unloading is of particular importance, too.
I simply don't see Roc as an easy adaptable aircraft for oversized cargo.
In fact, had this been thought as an airlifter, they would have gone with 4 x GE90-94B engines (the ones on the B777-200ER), which would offer much better operating costs. Instead they went with six B744 engines, that offer limited lifetime and higher operating costs. But since this was clearly a launcher aircraft, they expected few flight hours on the engines. Which makes me wonder about the life rating on the airframe. You can use a BMW X5 as a truck in a pinch. But you better don't use it as a workhorse.

[starchasercowboy]

“If you’re looking at space launches from airports, you’re able to usher in more of a democratization of space,” Chuck Beames, executive director of Stratolaunch Systems and president of Vulcan Aerospace, said in an April 8 phone interview. Allen’s ultimate goal: “putting space in the hands of every man.”

Building the plane first, testing it's performance envelope, collaborating with experianced companies, and then designing the spaceship.  Let Branson blaze a trail into space tourism, and learn from his mistakes. By the time ROC is flight testing, maybe an upscaled version of SS2 carrying more passengers, or a shuttle type space truck will be on the drawing board.

[R7]

ROC started out as an Air Force project through Scaled Composites/BAE systems called LOFTY.  Burt probably sold the idea to Paul after the WK1 SS1 success.

My google fu fails me. What was LOFTY about, just a carrier (for what?) or LV too?

[Blackstar]

“If you’re looking at space launches from airports, you’re able to usher in more of a democratization of space,” Chuck Beames, executive director of Stratolaunch Systems and president of Vulcan Aerospace, said in an April 8 phone interview. Allen’s ultimate goal: “putting space in the hands of every man.”

Building the plane first, testing it's performance envelope, collaborating with experianced companies, and then designing the spaceship.  Let Branson blaze a trail into space tourism, and learn from his mistakes. By the time ROC is flight testing, maybe an upscaled version of SS2 carrying more passengers, or a shuttle type space truck will be on the drawing board.

Except that they have now backed out of human spaceflight.

And as for Branson "blazing a trail"--when? He's been at it 10 years and doesn't seem very close to actually launching paying customers. So if the idea is to learn from Branson, that will be an awfully long school year.

[Oli]

“If you’re looking at space launches from airports, you’re able to usher in more of a democratization of space,” Chuck Beames, executive director of Stratolaunch Systems and president of Vulcan Aerospace, said in an April 8 phone interview. Allen’s ultimate goal: “putting space in the hands of every man.”

Problem is, if you're going to orbit from where you launch is really not THAT critical.

[Katana]

Also, reduced air drag allows flight profile with rapid acceleration and high T/W ratio, and reduced gravity loss.

Air drag and gravity loss for normal launcher is around 9400m/s-7900m/s=1500m/s

Total benefit from air launch may reach 2000+ m/s.

Biggest benefit of air launch is probably higher ISP allowed by initial ignition at altitude, in theory.  This only works if the first stage engine is designed to extract the higher ISP, of course, compared to a ground launch.   

 - Ed Kyle

[Katana]

Why isn't it possible to mere drop an OSC Minotaur and ignite it in air?

[Kryten]

Why isn't it possible to mere drop an OSC Minotaur and ignite it in air?

Technically, it's probably entirely feasible-the issues would be financial. There's not too much demand at that end of the market, and that you'd have great trouble paying for maintenance on such a large aircraft and it's unique infrastructure off of the payment for relatively small payloads.

[edkyle99]

Why isn't it possible to mere drop an OSC Minotaur and ignite it in air?

Technically, it's probably entirely feasible-the issues would be financial. There's not too much demand at that end of the market, and that you'd have great trouble paying for maintenance on such a large aircraft and it's unique infrastructure off of the payment for relatively small payloads.

Agreed.  A Minotaur 1 would be easiest, but still would require a specialized aircraft (too big for Stargazer).  Minotaur 3-5 (MX-based) would be a whole new ballgame since it would weigh nearly three times as much as Pegasus and would be fatter and longer.  I would expect a parachute-stabilized approach for these, like the Minuteman test years ago.  But, again, there would be little gained unless the first stage nozzle was extended.

The end result would still only be a rocket able to lift maybe two tonnes to LEO or 700+ kg to GTO.

 - Ed Kyle

[Skyrocket]

A Minuteman missile, on which Minotaur-1 is based, had already been airlaunched in 1974.

[Katana]

MX weight 97t
Roc payload capabilities 230t
Pegasus 2 proposed 211t, SRB diameter, 5m fairing, RL10 upperstage

Why build something twice larger and more complex than MX / Minotaur without using it ?

[Katana]

ls adding noozle extension to existing MX feasible?

[DaveJes1979]

Well, looks like they've got an airplane to nowhere.  At least for now.

If I were looking into a rocket for air launch, Stratolaunch should consider walking across the street and knocking on XCor's door.  At the very least to inquire about their piston rocket pumps.  It might even be worth trading against electric battery pumps. 

Forget about solids, you end up with too many stages and separation events (keep it down to 2).  And solids just aren't very safe if you will eventually put people at the front of the rocket.

Although there is a isp performance penalty vs. crogenic fuels, it might be desirable to have storable liquid propellants.  They are dense, don't have the hazards of, say, hydrogen, and most importantly it would eliminate fuel transfer between the mothership and rocket, simplifying operations.  Since they are not at cryogenic temperatures, you might even be able to make your structure completely composite, excepting an inner liner in the tanks.  N2O4/MMH is nasty stuff on the ground operations side, but is a pretty good performer.  This is low TRL, but worth looking into if one insists on non-toxic storable propellants: https://catalog.data.gov/dataset/low-cost-high-performance-non-toxic-self-pressurizing-storable-liquid-bi-propellant-pressu

It would be good to retain the Pegasus-style carbon composite wing for the initial launch and pull-up (saves about 1000 m/s of delta V).

[ChrisWilson68]

I think it could be very interesting as a launch platform for a point-to-point vehicle.

If not for people or cargo, couldn't the Air Force use a hypersonic bomber?

If it can fly hypersonic and land, it can surely take off from a runway too.  So what's the point in carrying it with a larger aircraft?  If it's just to extend the range, it's much easier to do this with air-to-air refueling.

[ChrisWilson68]

In fact, had this been thought as an airlifter, they would have gone with 4 x GE90-94B engines (the ones on the B777-200ER), which would offer much better operating costs. Instead they went with six B744 engines, that offer limited lifetime and higher operating costs. But since this was clearly a launcher aircraft, they expected few flight hours on the engines. Which makes me wonder about the life rating on the airframe. You can use a BMW X5 as a truck in a pinch. But you better don't use it as a workhorse.

There are plenty of airlines operating 747s with those engines and they have no problem flying them every day for many years and making a profit.  There's no way 747 engine lifetime or maintenance would be limiting factors for this vehicle as cargo carrier.

[ChrisWilson68]

“If you’re looking at space launches from airports, you’re able to usher in more of a democratization of space,” Chuck Beames, executive director of Stratolaunch Systems and president of Vulcan Aerospace, said in an April 8 phone interview. Allen’s ultimate goal: “putting space in the hands of every man.”

Building the plane first, testing it's performance envelope, collaborating with experianced companies, and then designing the spaceship.  Let Branson blaze a trail into space tourism, and learn from his mistakes. By the time ROC is flight testing, maybe an upscaled version of SS2 carrying more passengers, or a shuttle type space truck will be on the drawing board.

If you want to learn from others, you shouldn't start building your carrier aircraft until you've done that learning.

Anyway, there's probably not much to learn from a sub-orbital craft about orbital launch -- all the hard problems are very different.

[KSC Sage]

Although there is a isp performance penalty vs. crogenic fuels, it might be desirable to have storable liquid propellants.  They are dense, don't have the hazards of, say, hydrogen, and most importantly it would eliminate fuel transfer between the mothership and rocket, simplifying operations. 

There is no plan to transfer propellants between the Carrier Plane and the rocket.  The rocket is required to be fueled on the ground before take off.

[Kryten]

Although there is a isp performance penalty vs. crogenic fuels, it might be desirable to have storable liquid propellants.  They are dense, don't have the hazards of, say, hydrogen, and most importantly it would eliminate fuel transfer between the mothership and rocket, simplifying operations. 

Where does the engine come from? Energomash and Krunichev are now politically impossible, Yuzmash is far too risky, and AR haven't developed a new large hypergolic engine since the 60s (AFAIK).