Xenon Tetroxide rocket?

[JMBuilder]

Xenon Tetroxide is a compound that is only stable below -35.9 degrees celsius. I have an idea for a special rocket using this as fuel.

The compound is kept as a powder in a heavily refrigerated container. The powder is carried to a heating unit just inside the thrust nozzle. The higher temperatures cause the compound to destabilize, creating an explosion and producing thrust.

Does Xenon Tetroxide explode with enough force to be significant? If so, would it be efficient enough to use as a rocket fuel?

[shynung]

There's a few problems with using XeO₄ as rocket fuel.

First, as you mentioned, it is in powder form in the storage temperature (-35.9 ^oC), rather than liquid. Powders are harder to move around using pipes and pumps; a complicated mechanism is needed, which reduces the thruster system's effective TWR.

Second, rocket propellants are supposed to burn consistently, not explode (excluding pulsed-propulsion systems). I have no knowledge about its decomposition reaction properties, but if XeO₄ cannot be made to burn steadily on its own (including the use of additives), I see no obvious advantage to use it as rocket propellant.

Edited June 11, 2014 by shynung

[Streetwind]

There's also the question of energy yield. There are a whole lot of unstable compounds in the world, but only a small selection is used for rocket fuel because the rest doesn't release enough energy to make it worth the hassle of handling them.

I mean heck, we have oxidizers so powerful they will set water on fire by merely coming into contact, that react so violently with almost every element in the periodic table that the hardest part in producing them is finding a means of storage that doesn't spontaneously disintegrate at the mere thought of holding whole liters of it, and are so unbelievably toxic that the thought of a nuclear thermal rocket would sound reasonable to the broad public in comparison. Yet the energy released by those reactions isn't that much higher than the 2 H2 + 1 O2 = 2 H2O recombination reaction that's been used for fifty years or more. The gains just aren't worth the hassle, which is why we're not using them.

So the question you should be asking yourself first is: does the chemical decay of XeO4 produce enough energy to be worthwhile?

[lajoswinkler]

No, no, no and no. Xenon tetroxide in a rocket does not make a vehicle. It makes a very expensive pipe bomb.

[DaveofDefeat]

If you could make rocket fuel out of that, you might as well just use composition B and be done with it.

[Horn Brain]

Suppose this works great. You're still SOL because Xenon is an extremely heavy atom, which means that your exhaust velocity will be much lower and therefore your rocket will be much less efficient than it could be otherwise.

This is partly why H2 and O2 are the top of the line fuels: they produce H2O as exhaust, which has a molecular weight of 18, compared to what I'm assuming will be Xe + 2O2, which has a combined molecular weight of 131+2*32=195. Divide by three for the average and you get 65 or so. Roughly speaking, for the same temperature you're going to get about 1/2 the molecular velocity (on average), which means 1/2 the Isp!

Edited June 11, 2014 by Horn Brain