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... because if hot gas and/or propane finds its way into the N2O tank or the other way around, ...
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The correct hydrocarbon for a self-pressurized liquid fueled rocket using N2O as an oxidizer is ethane, C2H6, not propane. Ethane/nitrous oxide is a developed storable noncryogenic propellant system. The vapor pressure curves of ethane and nitrous oxide are well matched and both have nearly identical critical points.Hello,
I was going to pressurize the propane tank with N2. Now the decision I've been wrestling with is whether to complicate a system (that I really don't want to complicate any more than absolutely necessary) by adding a third tank designated for N2 that feeds into the fuel tank or pressurize the tank directly with N2, which has its own set of problems. Careful jet selection should be able to get the stoichiometric fuel/oxidizer ratio right.
This is an extreme longterm project that probably won't see a wet run let alone a working rocket for year(s).
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... because if hot gas and/or propane finds its way into the N2O tank or the other way around, ...
Won't "flap guidance" system correct it?..
-Alex
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Matchng self-pressurizing tank pressures by using enthane or ethylene reduces system complexity and increases system reliability since you don't need a third high pressure gas tank and pressure regulator.
... because if hot gas and/or propane finds its way into the N2O tank or the other way around, ...
Won't "flap guidance" system correct it?..
-Alex
It wouldn't effect it at all. I was referring to the rocket itself having flaps to keep it flying straight (extremely primitive avionics). They are exterior and unrelated to the motor.
@Bob: It is indeed a better match based on only that parameter (there is no 'correct' fuel perse). Although it is better established in use with ethane. Prop/N2O has also been researched as a pressure-fed system by DARPA, whose paper I've read.
So far every question asked has been striking to the heart of the preliminary decisions I was making in order to plan the motor. (Which is good, these are the most basic important ones). My 'trade off triangle' here is between complexity, accessibility of components and suitability/results. I went with propane for the easy of obtaining propane over ethane at the cost of complexity with the vapor pressure differences of the fuel/oxidizer. All that being said, I'm not above changing my mind for the sake of simplicity. Reducing my rocket's dry weight by an additional tank is still a pretty compelling argument but obtaining it in quantities I'll be using will be far more difficult.
A piston system will not be possible, although it would be an elegant solution; too hard to access.
I've also considered pressurizing the propane with CO2, but it's 'less inert' than N2 despite being a better pressure match with N2O.
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