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Post by lorentz99 on Oct 15, 2017 19:41:15 GMT
I have always believed that Thrust Power is roughly the energy carried away every second from an engine in the form of the kinetic energy of the propellant. (Minus the energy they have 'in directions perpendicular to thrust') And that it is therefore Exhaust velocity*Thrust/2. But almost all stock resistojets have far greater thrust power than supplied power. This seems to violate energy conservation. What is I am overlooking? What does thrust power mean?
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Post by Kerr on Oct 15, 2017 21:48:56 GMT
I have always believed that Thrust Power is roughly the energy carried away every second from an engine in the form of the kinetic energy of the propellant. (Minus the energy they have 'in directions perpendicular to thrust') And that it is therefore Exhaust velocity*Thrust/2. But almost all stock resistojets have far greater thrust power than supplied power. This seems to violate energy conservation. What is I am overlooking? What does thrust power mean? What you are overlooking is the fact that CoaDe's module design just loves to violate the first law of thermodynamics. |
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Post by n2maniac on Oct 16, 2017 6:21:21 GMT
You are correct, I would call it a long-standing bug. Best as I can tell there is a minus sign flipped on the dissociation energy or heat of formation.
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Post by treptoplax on Oct 21, 2017 20:05:20 GMT
I think there's also an assumption that the tanks are pressurised, so zero-power resistojets actually have some thrust, but it sounds like you're seeing a bigger effect than that.
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Post by n2maniac on Oct 21, 2017 23:30:20 GMT
I think there's also an assumption that the tanks are pressurised, so zero-power resistojets actually have some thrust, but it sounds like you're seeing a bigger effect than that. Yes, and the effect is exceptionally pronounced across a small exhaust temperature range associated with its dissociation temperature. |
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