On Sun, 2004-06-13 at 07:26, Jake Anderson wrote: > the energy that goes into pressuring the propellants isnt waisted > that energy is converted to KE too (through the injectors and as pressure > drop across the nozzle) Right so far, the pumping energy plus the chemical energy heat the fuel, which then expands through the rocket engine. Various inefficiencies in the rocket engine give us an exhaust gas with velocity v in the rotating frame, and thus 0 in the fixed frame, but with a lot of residual energy in the form of heat and disassociated chemical fractions and residual pressure.
The engine doesn't accelerate past v because the net forces all balance. The exhaust is stationary, momentum zero. the source fuel is stationary with zero momentum, so the steady state behavior has the engine with constant momentum and thus velocity. I don't think I can explain it any better than that without diagrams, so if there is still confusion mail me and I'll generate a real calculation with real fuels and reactions. I suspect that means LOX & propane with an isp of 250 seconds and thus a rotating velocity for the engine of about 2500 m/s, with an engine pressure of 70,000 psi. I've had similar problems explaining this before, and it helps to have the right drawings and such. So why don't we take this offline, and I'll post a pointer to my completed article when we have all hashed it out? Unless of course the rest of the list wants to see the intervening confusion. >> So we are generating thrust by the centrifugal pumping action alone, >> then heating the fuel? > No. The scenario is that we are predominately generating the *pressure* > by the centrifugal pumping action. The propellent undergoes an > exothermic chemical reaction in the tip rocket liberating gaseous fluid > that exits through a De Laval nozzle. Thats precisely correct. > > Clearly there is something impossible in the problem description; > otherwise there would be no paradox. The puzzle is: "what is wrong?" > Consider the momentia! Roger Gregory [EMAIL PROTECTED] http://www.halfwaytoanywhere.com _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
