Stratolaunch: General Company and Development Updates and Discussions

[Kabloona]

It's a prestige project. That's why Allen hasn't cancelled it.

This is the textbook example of how to make a small fortune in aerospace: start with a large fortune.

[Steven Pietrobon]

With a liquid rocket: The moment it is released from the carrier aircraft it will decelerate, which will cause the liquid to move away from the tank exits. Won't it be difficult to prime the plumbing and pumps with the liquid at the top of the tanks?

As the tanks are nearly full and the vehicle horizontal, the small horizontal deceleration will only slightly tilt the level of the propellant. A small positive angle of attack should should avoid any problem of gas at the bottom of the stage, the gas will be at the top of the stage.

[MKremer]

I can see a liquid booster being much more complex, since the ground-based GSE needs to fit within the fuselages (and possibly part of the central wing as well). But maybe not impossible. The main problem immediately apparent is splitting the needed GSE equipment and tanks (gases and LOX replenishment) between the two fuselages so they remain balanced. (Probably means an extra fuel tank in the LOX/gases section to transfer into for weight balancing.)

The thing that I think could be most interesting is the umbilical connections between the central wing and the rocket. That's a lot of plumbing (gas, cryo, high pressure hydraulics) and electrical connections between one or two umbilicals and the rest of the rocket on the top side. It would certainly look unbalanced because of that.
With that in mind, a liquid booster would most probably require a solid upper stage, at least to simplify the plumbing required to support it from the umbilicals.

The trade-off of less payload mass to orbit with an all-solid design could be worth not having to design, implement and support the much more complex liquid booster requirements (not only for the plane, but for the booster itself).

[Robotbeat]

But then, the argument extends to the carrier craft as well: why not just use a bigger solid booster so you don't need the enormous plane?

[MKremer]

But then, the argument extends to the carrier craft as well: why not just use a bigger solid booster so you don't need the enormous plane?

But then you lose the "cool factor" of a plane launch.   (j/k)

That raises the question of 'launch on need' time.  Would it take more, or less, time to horizontally attach a payload to the rocket, then attach it to the plane, take off, and launch; versus the 'traditional' method for a ground launch?

The only advantage I can think of offhand is a plane launch isn't totally bound by weather/wind conditions (other than those required for takeoff).

[Steven Pietrobon]

Non-toxic storable propellent combinations are available. One of them is Hydrogen Peroxide and Kerosene. It has about the same average density as a solid propellant stage with 10% to 15% better Isp.

[Katana]

Non-toxic storable propellent combinations are available. One of them is Hydrogen Peroxide and Kerosene. It has about the same average density as a solid propellant stage with 10% to 15% better Isp.

Even more dangerous than toxic propellants.

[Archibald]

Non-toxic storable propellent combinations are available. One of them is Hydrogen Peroxide and Kerosene. It has about the same average density as a solid propellant stage with 10% to 15% better Isp.

Even more dangerous than toxic propellants.

Wrong. Kerosene is much less dangerous than N2H4. While H2O2 is less dangerous than N2O4 - it is not as corrosive or toxic as storable propellants. I do know the main issue is the risk of explosion, but I think if  handled properly nothing will happen.

[Archibald]

Let's suppose the rocket do not use RP-1 but JP-5 kerosene, like the 747 engines used by the Roc carrier aircraft. 

How about transfering jet engine propellants from the aircraft to the rocket just before launch ?

[Bob Shaw]

Non-toxic storable propellent combinations are available. One of them is Hydrogen Peroxide and Kerosene. It has about the same average density as a solid propellant stage with 10% to 15% better Isp.

Even more dangerous than toxic propellants.

Wrong. Kerosene is much less dangerous than N2H4. While H2O2 is less dangerous than N2O4 - it is not as corrosive or toxic as storable propellants. I do know the main issue is the risk of explosion, but I think if  handled properly nothing will happen.

Hydrogen Peroxide is indeed a dangerous chemical to handle, and can spontaneously break down. It was widely used in torpedoes (which used 'rocket' I/C engines to run their props) and led to terrible accidents, including the sinking of HMS Sidon (P 259) at Portland in 1955. 'High Test Peroxide' remained a favourite of British rocket companies, however, but none of their rockets were anywhere near people when in action.

I wouldn't care to be the crew of the carrier aircraft, though in this day and age there's probably no need for any humans to be aboard.

[Steven Pietrobon]

Hydrogen Peroxide is indeed a dangerous chemical to handle, and can spontaneously break down.

I agree that HTP is a dangerous chemical to handle, but so are LOX, RP-1, LH2, LCH4 and NO. LOX can also "spontaneously explode" if exposed to the wrong materials and NO can explode if it gets too hot. In the proper container that has been correctly treated and made clean, HTP will do nothing. The same is true for LOX. HTP does not explode unless there is a contaminant source, also true for LOX. In fact, most times a contaminate does nothing. This can cause people to become lax and then you can have accidents. If standard procedures are followed, HTP is safe to use. This is basically true for all rocket propellants.

'High Test Peroxide' remained a favourite of British rocket companies, however, but none of their rockets were anywhere near people when in action.

I think that is true for all rockets (the exception being astronaut launch vehicles), not just ones that used HTP.

[Bob Shaw]

I think that is true for all rockets (the exception being astronaut launch vehicles), not just ones that used HTP.

Being aboard a carrier aircraft is pretty close!

[TrevorMonty]

The SOAR is based on VEHRA.

Dassault Aviation is studying a reusable space transportation system to launch satellites into low Earth orbit. It comprises an airborne reusable hypersonic vehicle and a subsonic carrier aircraft. The use of the technique of airborne launch offers an increase of performance with regard to the launch from the ground and allows to free itself from the heaviest constraints of the launch infrastructures. VEHRA family comprises three vehicles:

VEHRA “Light” (10 t) : technological demonstrator;
VEHRA “Medium” (30 t) : to inject small payloads (250 kg) into low Earth orbit;
VEHRA “Heavy” (200 t) : to launch 7t into low Earth orbit;
Moreover, a manned version is also proposed to carry six people up to 100 km of altitude.

Stratolauncher would be the ideal plane for launching the VEHRA "Heavy".  Vulcan Aerospace just need somebody to develop a VEHRA "Heavy" type vehicle, SNC maybe. A vehicle based on DC should be in Medium class.

[kch]

Let's suppose the rocket do not use RP-1 but JP-5 kerosene, like the 747 engines used by the Roc carrier aircraft. 

How about transfering jet engine propellants from the aircraft to the rocket just before launch ?

That's the propellant combination (HTP and jet fuel) that Beal intended to use in all three stages of the BA-2.  The second and third stage engines were test-fired multiple times, with (IIRC) good results.

Transferring jet fuel to the rocket before launch would be similar to the aerial refueling phase of a Black Horse flight, without the rendezvous-and-connect problem. 

[RanulfC]

Hydrogen Peroxide is indeed a dangerous chemical to handle, and can spontaneously break down. It was widely used in torpedoes (which used 'rocket' I/C engines to run their props) and led to terrible accidents, including the sinking of HMS Sidon (P 259) at Portland in 1955. 'High Test Peroxide' remained a favourite of British rocket companies, however, but none of their rockets were anywhere near people when in action.

As long as the H2O2 tank is vented there is no danger of explosion, and it's no more dangerous than handling LOX and a LOT less dangerous than most 'storable' propellants. Just check out an MSDS:
 http://wcam.engr.wisc.edu/Public/Safety/MSDS/Hydrogen%20peroxide%20.pdf

Brit's had the most success using it as a rocket propellant so it stands to reason they might favor it but it was widely used in early spacecraft.

Storage is actually pretty straight forward as noted here:
http://www.hydrogen-peroxide.us/history-US-General-Kinetics/AIAA-2005-4551_Long_Term_Storability_of_Hydrogen_Peroxide.pdf

What's neat to note is that, while not widely known for some reason, storage of H2O2 at a temperature of around 5C/41F shows NO breakdown over time. Samples stored for a decade or more showed zero breakdown.

Compare that with 182.96 °C/ −297.33 °F for LOX

I wouldn't care to be the crew of the carrier aircraft, though in this day and age there's probably no need for any humans to be aboard.

StratoLaunch doesn't ignite the LV while attached to the carrier aircraft you know. Really though, some proper heat/plume shielding and firing up the LV engines while still attached to the carrier wouldn't be that much of an issue. The military does it all the time. (The whole "drop-the-missile-then-fire-the-engine" thing has been blown out of proportion by media. In actual practice only a FEW weapons drop-and-fire with most firing and then sliding off a rail attached to the aircraft during launch) Your criteria is time and exposure to the exhaust plume, if you keep the exposure short, say a few seconds then you hardly need any shielding at all. The longer the exposure the more shielding but really you could do something as simple as activate water sprayers along the aft fuselages/tail and be fine for minute or more. (At which point you're now worried about the thrust rather than the heat as the LV will probably be putting out more power than the aircraft engines )

Steven: Actually H2O2 does in fact "explode" if not properly stored. It's how US rocket engineers originally convinced the military in WWII to NOT fund peroxide experiments When told to proceed with experiments, (hey the Brits and Germans were working with the stuff after all ) American rocket scientists contracted to build a non-vented peroxide storage container on an Army base, had it filled and left it over the weekend... After the explosion due to de-composing peroxide in non-vented container they said "See how dangerous this stuff is?" and the Army agreed and dropped the idea until after the war.

Randy

[Bob Shaw]

Brit's had the most success using it as a rocket propellant so it stands to reason they might favor it but it was widely used in early spacecraft.

As Uncle Roger used to say, 'Ah, DeHavilland!'...

[MP99]

Non-toxic storable propellent combinations are available. One of them is Hydrogen Peroxide and Kerosene. It has about the same average density as a solid propellant stage with 10% to 15% better Isp.

Even more dangerous than toxic propellants.

Wrong. Kerosene is much less dangerous than N2H4. While H2O2 is less dangerous than N2O4 - it is not as corrosive or toxic as storable propellants. I do know the main issue is the risk of explosion, but I think if  handled properly nothing will happen.

Hydrogen Peroxide is indeed a dangerous chemical to handle, and can spontaneously break down. It was widely used in torpedoes (which used 'rocket' I/C engines to run their props) and led to terrible accidents, including the sinking of HMS Sidon (P 259) at Portland in 1955. 'High Test Peroxide' remained a favourite of British rocket companies, however, but none of their rockets were anywhere near people when in action.

I wouldn't care to be the crew of the carrier aircraft, though in this day and age there's probably no need for any humans to be aboard.

Also, Kursk, from fuel in the torpedoes.

Cheers, Martin

[douglas100]

It's still used in a current LV--to drive the Soyuz first and second stage turbopumps.

[Archibald]

Transferring jet fuel to the rocket before launch would be similar to the aerial refueling phase of a Black Horse flight, without the rendezvous-and-connect problem.

No, I meant transfering propellants with the rocket still attached to the aircraft. It would be a bit like the SSME-ET pipping (that went through the heatshield, btw)

Run pipes from the Roc kerosene tanks,  then onto the rocket kerosene tank.

I don't know if there might be some weight savings - or nothing ?

[kch]

Transferring jet fuel to the rocket before launch would be similar to the aerial refueling phase of a Black Horse flight, without the rendezvous-and-connect problem.

No, I meant transfering propellants with the rocket still attached to the aircraft.

So did I -- that's what the "without the rendezvous-and-connect problem" was about (you're already connected)!