I’m quite curious. The ME 163 fuel sometimes exploded just sitting on the runway. Would more modern stable fuels work to increase efficiency and lessen the chances of an explosion?
Maybe, but the fuel is what was the problem. It was way to unstable for practical use at the time.
The motor of the Me 163:
from http://www.walter-rockets.i12.com/walter/me163a.htm
I’m waiting for somebody with more experience in rocket fuel to post! 
No doubt (the Russians have liquid fuelled ICBMs sitting in silos for years with fuel in). However, you would have to overhaul the entire fuel system to make it properly safe (if it didn’t leak in the first place there could be no explosions) and in any case the aircraft wasn’t very impressive by modern standards so there wouldn’t be any point.
The engine was a Walter model, designed around the chemical properties of highly concentrated hydrogen peroxide.
Hydrogen peroxide, even the 3% solution sold in pharmacies, reacts with potassium permanganate (also available in pharmacies) as a katalyst to form oxygen and water.
2H2O2 --(Katalyst)----> H2O + O2+ heat
Using highly concentrated H2O2 (appr. 80%), the water will turn into steam immediately. Additional fuel like diesel fuel can be injected into the reaction chamber to burn using the excess oxygen and increasing the reaction enthalpy.
Later models used a solid katalyst of MnO in the reaction chamber instead of the KMnO4 solution.
The whole engine design bases on the this chemical reaction. Other fuels will not work with this engine.
The advantage is that the fuel combination (H2O2 and katalyst) is hypergolic, this means that they react on contact without requiring an ignition system.
The drawback is that hydrogen peroxide at this concentration is so reactive that it will react with about any organic matter. 3% hydrogen peroxide will bleach hair and desinfect. 30% hydrogen peroxide (commercial highly concentrated) will leave white stains on the skin through it’s bleaching properties (it breaks down and the free oxygen will react with the organic matter).
T-Stoff (80% H2O2) is extremely unstable and dangerous.
A change of fuels would require a complete redesign of the engine, in fact a new engine.
Jan
That’s interesting to know. I should think that with modern technology a whole new engine could be made if that is necessary, which given the apparent design certainly would be. I’ trying to get ahold of a Komet, or at least find the money to have a plane designed with the same body. I personally think the plane has a sleek look.
No doubt (the Russians have liquid fuelled ICBMs sitting in silos for years with fuel in). However, you would have to overhaul the entire fuel system to make it properly safe (if it didn’t leak in the first place there could be no explosions) and in any case the aircraft wasn’t very impressive by modern standards so there wouldn’t be any point.[/quote]
Off topic I know, but you cant leave liquid fuel in an ICMB, you have to fuel it close to launch. I do agree with your point though.
Depends.
The first ICBMs using cryogenic fuels, like the Atlas, the Thor and the Juno needed to be fueled right before launch.
The Titan series was developed to use storable liquid fuels , so that the rockets could stay in their missiles readily fueled.
The problem was that these fuels had some highly undesirable properties:
Concentrated, smoking nitric acid (HNO3) as an oxydiser, toxic, highly corrosive and will set any organic matter it touches on fire and
Unsymetric Dimethylhydrazine, which is quite poisonous.
High power storable solid fuel rockets were developed after the US Navy had the idea of deploying nukes on submarines. Cryogenic fuels would be totally unsuitable for a submarine due to storage problems and image the result of a major HNO3 leak into a submarine.
The only alternative were solid fuels.
Jan
I stand corrected mate thanks. However I thought we were discussing Soviet liquid fuelled ICBMs. I know that one of the indicators that they may be preparing to launch an attack was the fuelling of the ICBM fleet. But on thinking about it, they probably would have had to keep a fair few fuelled and ready to go.
I’m sure there’s a myriad of more stable fuels - the range of stuff you can use as rocket fuel is breathtaking. A coursemate at University did his Master’s research into a hybrid rocket motor using an oxidiser and lengths of solid plastic tube as the fuel. I don’t recall whether it was perspex or some type of heavy duty polythene tube. Not entirely sure which plastic but either way - some regular every day plastic!!! The fact that it was a working rocket motor was quite surprising to a (relative) layman such as myself.
I suppose it all depends on what performance you expect out of your stable fuel.
For some reason I’m thinking of Spaceship One here, but that’s probably because it’s the only other rocket powered “aircraft” of a scale beneath the Shuttle that is coming to mind! Perhaps look into what fuel that uses - I’m 100% certain you’ll find it’s non-toxic, and composed of seemingly innocuous substances… I seem to recall the fuel is rubber based!!! Not sure about oxidiser.
When it comes to picking fuel, it works in your favour that for once this is a rocket that doesn’t have to reach orbit! You are using aerodynamic surfaces for lift, and nobody even says you have to match the 163’s top speed, so you could compromise on performance. Perhaps a new motor using non-toxic, more stable fuels will be more than sufficient for a short burn to give you a bit of a pleasure flight at speeds less ambitious than those achievable by the original fuel. You don’t have to enter combat so high speeds won’t matter so much!
Oh, additionally, I think you’re nuts! But hats off to you if you pull it off! 
Like Jan says, it depends on the era. The very early ones used Cryogenic fuels - so had to be fuelled immediately prior to launch. The more recent ones were storable propellant - the SS-11 for instance used UDMH (a hydrazine derivative) as the fuel and Nitrogen Tetroxide as the oxidiser.
The soviets even sent liquid fuelled ICBMs to sea with the SS-N-8 (and possibly others). Those would have to be storable propellants, and even then would not be something I’d care to have on the same submarine as me…
The Walter process was also used to power submarines, the highly concentrated H2O2 was pumped into a reaction chamber, where it disintegrated upon contact with blocks of MnO, producing superheated steam and excess oxygen. The mix was led into a combustion chamber and diesel fuel injected, raising the temperature and energy of the gases.
Then the gases were ducted into a turbine to extract the energy and power the ship. The advantage of the process was that it was a) quiet,
b) allowed longer underwater journeys than a diesel-electric boat (only limited by the tank capacity for fuel) and c) that the excess oxygen and the water produced could be used by the ship’s enviromental system (if no diesel fuel was added, e.g. while running the ship at normal cruise or slow speed.
The Walter U-boats were the first real submarines, not just submergibles, they could stay underwater for days or weeks if required. They were only developed closely to the end of the war and only a few built. The introduction of nuclear power though and improvements in diesel-electric boats, plus the dangers of handling the fuel, didn’t make them too popular after WW2.
Jan
Thanks for the above, I really need to learn more about this fascinating subject too.
Oh, additionally, I think you’re nuts! But hats off to you if you pull it off!
I’m not nuts. I’m normal. It’s the rest of the world that has issues!
As long as we seem to be jumping from topic to topic, I wonder if anyone knows what powers the SR 71 recon plane. I know it flies in the upper atmosphere and moves extremely fast
DO you think on this plane
Function: Very-high-speed, high-altitude Aerial Reconnaissance
Length: 107 feet 5 inches
Wingspan: 55 feet 7 inches
Height: 18 feet 6 inches
Max takeoff weight: 140,000 pounds
Max Speed: Mach 3.2 above 75,000 feet
Crew: 2 (Pilot and Reconnaissance Systems Operator)
Number built: SR-71A: 29…SR-71B: 2…SR-71C: 1
Fixed Armament: none.
Engines: 2 Pratt & Whitney J-58 engines 34,000 lbs thrust
Nothing more complicated than manky big afterburning turbojets! Of course, the SR-71 benefits from having very good design of the engine installation - the intakes being particularly clever. It’s cruise regime is all with after-burner - rather rare but the only way to do it with a turbojet really! And funnily enough the most economical way of covering the distance for the aircraft. It would still need frequent in flight refuelling, however.
Because of the high temperatures endured by the airframe while travelling so fast, and hence the relatively huge thermal expansion of the panels , the Blackbird had to be made such that they could have quite a large difference between “cool” and “hot” with things not really fitting right until it was “up to temperature”, as it were. Everything was that much smaller and hence such a bad fit while cool that the thing was notorious for leaking like a sieve. This might strike you as a terrible fire hazard to have an aircraft leaking so much fuel on a airbase apron, but the fuel used (JP-7?) is actually quite safe… because of the high temperatures in the operating environment, it was developed to have a very high flash point. I’ve heard that if you had a fire with normal jet fuel, you could pour this stuff on to put the fire out. Possibly urban legend but hey, a good story! The stuff is also ridiculously expensive - which might explain why they were so eager to retire the damn thing at the start of the 90’s!
EDIT for simply typos
Whilst we are mentioning unstable fuels etc.
There was an accidnet in the 1950’s very similair to the Kursk disaster involving the same type of fuel. A British prototype submarine was re-fuelling in Poole harbour and IIRC went down with all hands, shortly afterwards the British ceased research into this type of fuel, but it was continued by the Russians, who continued refienemnts and safeyty procedures were put in place but the fuel itself was still temperamental - Leading to the Kursk disaster many years later,
I will look up details in a bit Im just running out now.
HMS Sidon - not a prototype submarine, but a prototype torpedo.