More developed European Space Agency/Program

[GTX_Admin]

Speaking of MUSTARD:

[Weaver]

I remember reading about another interesting scheme, but I can't recall what it was called. The idea was that you had a spaceplane powered by turbofans and a kerosene/LOX rocket motor. The spaceplane would take off horizontally on jet power alone at a relatively low weight, with it's LOX tank full but it's kerosene tanks mostly empty. It would then fill up the latter via air-refuelling before lighting up the rocket and pointing the nose upwards.

IIRC it was a cost-conscious private-enterprise job, so it would have used an exisiting Russian rocket motor and a KC-135 tanker. However you could see the advantage of having a faster, higher-flying tanker developed specially for it if the budget allowed.

[elmayerle]

I believe the proposal was named "Black Horse" and a smaller version was referred to as "Black Colt" and I've thought it made considerable sense.  If Boeing's Sonic Cruiser had been developed, a tanker version of that would be perfect for this application.

[Weaver]

Ah, thanks for that! Managed to find something out about it now:

http://www.ai.mit.edu/projects/im/magnus/bh/analog.html

I got it a bit wrong: it's the oxidiser that's transferred in flight, not the fuel, since the former represents a much greater weight/volume of the total fuel requirement: HTP:JP-5 ratio is about 7.3:1. I'm not crazy about HTP but it seems to be the best option here. Best refuelling performance is M=0.85 at 43,000ft using a KC-135Q with it's isolated offload fuel system modified for HTP. Not sure that a dedicated tanker with higher speed/height performance would be worth having now if 43,000ft is feasible. The optimised Black Horse proposed would have been all-rocket-powered with two sea-level optimised motors for take-off and five 43,000ft-optimised ones for the orbital shot, all based on the same core engine (to reduce development cost). Black Colt used jets and a rocket, but could only refuel at 20,000ft.

All makes a hell of a lot of sense to me! In the context of a European space programme, this gives a real reason to develop the spaceplane due to it's launch flexibility: you can fly out over the Atlantic and turn around to launch eastwards instead of having to ship the whole thing to Kourou, and if it does blow up in flight, it's no worse than any other aircraft crash. Britain had done a lot of work to make HTP operationally useable for the SR.177 so that would feed straight in.

[Rickshaw]

The British were particularly enamoured of HTP for some reason as a rocket fuel.  Most of their major projects used the stuff, despite it's fearsome reputation.   Ideally suited perhaps more for use from desert spaceports (Woomera), rather than wet tropical ones (French Guyana)?  It does have some advantages in that you don't need to carry separate fuel, by pumping the HTP over a catalyst instead.  However, as a monopropellant it has a fairly low specific impulse which limits its usefulness.

[elmayerle]

Hmm, that leads to the interesting thought of using it in monopropellant form for reaction control thrusters and bipropellant form for main engines; it would simplify the fueling aspects.

[Weaver]

HTP's main advantage in the context of the air-refuelled spaceplane is that it's a room-termperature liquid so the tanker and it's hardware can be relatively standard, rather than trying to get into the unknown territory of air-refuelling cryogenics or pressurised gas. Basically, you'd "just" have to pay attention to the seals and materials used to handle the HTP. The Royal Navy were planning to use it for carrier-based SR.177s and at least one of the carriers got as far as having the HTP tankage installed, so moisture can't be that much of a problem with it.

Passing HTP over a platinum catalyst gets you 500 deg C, oxygen-rich steam, which makes a nice low-power rocket in it's own right: the Germans used this technique for RATO units in WWII. I presume I'm right in thinking that if you spray vaporised kerosene into that mixture then it will spontaneously ignite? If so, then that's another advantage, i.e. it doesn't need an ignition system, or have I got the wrong end of the stick? If I'm right, then it would have the advantage of hypergolics (reliable ignition) without the disadvantage of a huge explosion if the fuels became accidentally mixed (say in a crash).

[Rickshaw]

HTP's main advantage in the context of the air-refuelled spaceplane is that it's a room-termperature liquid so the tanker and it's hardware can be relatively standard, rather than trying to get into the unknown territory of air-refuelling cryogenics or pressurised gas. Basically, you'd "just" have to pay attention to the seals and materials used to handle the HTP. The Royal Navy were planning to use it for carrier-based SR.177s and at least one of the carriers got as far as having the HTP tankage installed, so moisture can't be that much of a problem with it.

The Royal Navy abandoned the use of HTP in torpedoes after the loss of HMS SIdon:

On the morning of 16 June 1955, Sidon was moored alongside the depot ship HMS Maidstone in Portland Harbour. Two 21-inch Mark 12 High test peroxide-powered torpedoes, code-named "Fancy", had been loaded aboard for testing. Fifty-six officers and crewmen were aboard.

At 08:25, an explosion in one of the Fancy torpedoes (but not the warhead) burst the number-three torpedo tube into which it had been loaded and ruptured the forward-most two watertight bulkheads. Fire, toxic gases, and smoke accompanied the blast. Twelve men in the forward compartments died instantly and seven others were seriously injured.

Source]

It was believed that moisture got into the torpedo fuel tank and caused a spontaneous explosion.  The Royal Navy abandoned all development of HTP fuelled torpedoes afterwards.   So, I've always wondered how they were going to handled HTP onboard carriers.   The RAF which used it for the fuel on their Blue Steel missiles had to take very great precaution with it when servicing the Blue Steels.  Blue Steel use a bipropellant rocket engine with HTP and Kerosene.

Passing HTP over a platinum catalyst gets you 500 deg C, oxygen-rich steam, which makes a nice low-power rocket in it's own right: the Germans used this technique for RATO units in WWII. I presume I'm right in thinking that if you spray vaporised kerosene into that mixture then it will spontaneously ignite? If so, then that's another advantage, i.e. it doesn't need an ignition system, or have I got the wrong end of the stick? If I'm right, then it would have the advantage of hypergolics (reliable ignition) without the disadvantage of a huge explosion if the fuels became accidentally mixed (say in a crash).

Unless there is any moisture present which is extremely likely.  Even if the atmosphere is humid, that can be enough.

[Weaver]

I don't understand the idea that moisture causes HTP accidents. 98% HTP is 2% water anyway, and the standard safety precaution for an HTP spill is to flood the area with water to reduce the concentration. HTP's greatest risk is that a relatively large range of common materials can act as a catalyst to provoke it's decomposition into oxygen-rich superheated steam, which then causes damage by a) it's temperature, b) increasing the pressure in a closed space or c) feeding an already exisiting fire with oxygen.

[jcf]

From the navweaps site in reference to the failed Brit torpedo:
"Notes:  This design was developed from German and USA hydrogen-peroxide torpedoes of World War II, but generally was a Mark 8 torpedo body modified to use HTP.  Renamed "Fancy" sometime during development.  Hydrogen-peroxide is a notoriously unstable fuel, as was shown when the "S" class submarine HMS Sidon loaded two Mark 12 torpedoes on 16 June 1955 for a test firing planned for later that day.  Sidon was very badly damaged when one of these torpedoes exploded in her No. 3 torpedo tube, killing 13 men.  Sidon was raised a few days later, declared CTL and was eventually scuttled as a sonar target.  Another Mark 12 torpedo suffered an explosive failure on the Arrochar test range during the same year.  The development program was eventually canceled and all of these torpedoes were withdrawn from service in 1959.  An analysis of the failures showed that the basic problem was the decision to reuse the Mark 8 torpedo body.  Hydrogen-peroxide in contact with materials other than synthetic rubber and porcelain is corrosive and explosive.  The British shared their design studies and failure analysis with the Swedish Navy who profited from this knowledge to make their reliable and high-speed Tp 61.  This implies that had the British continued HTP development they might have had a high-speed torpedo much sooner."

http://www.navweaps.com/Weapons/WTBR_PostWWII.htm

Bolded italics added.

Bugger all about 'moisture sensitivity' in the following paper:
http://www.student.montefiore.ulg.ac.be/~teney/h2o2propulsion/The%20safe%20supply%20and%20handling%20of%20HTP.doc

Also nothing about avoiding moisture in the Safety Data Sheets, not surprising as water is the primary dilutent for H₂O₂.

[elmayerle]

Hmm, HTP over a catalyst sounds like a comparatively benign alternative to Hydrazine over a catalyst such as some aircraft emergency power systems use.  Both seem to have very exacting requirements for materials they come into contact with (I've plumbed Hydrazine lines for an emrgency power system, I had to be quite selective in materlial selection and had to use some special hoses without the standard anti-static-electricity internal coating because it would catalyze the Hydrazine).  That plumbing effort also ended up using titanium lines and beam seal fittings (normally used for 4000+ psi hydraulic systems) to prevent problems and those positive seal fittings to prevent leaks.  I would imagine that the same approaches would work for handling HTP.

[aerospacer]

A pretty good compilation of HTP related data and information and discussion thereof can be found at http://hydrogen-peroxide.us/uses.htm and http://hydrogen-peroxide.us/chemical.htm. Note especially the paper AIAA 2007-5468.

Martin