On 2/5/04 at 7:10 PM David Megginson wrote:
>Curtis L. Olson wrote: > >> I see the same thing in the JSBSim c172, except that it spins down >> rather quickly and stops. > >I've never shut down an engine in flight in real life, but from reports >I've >heard, you have to bring a 172 almost to the stall to stop the propeller >from windmilling; once stopped, however, it will stay stopped at a more >reasonable speed. > JSBSim - very crude currently - hardwired -1.5 HP resistive power when engine cutoff but still windmilling. This is probably on the very low side - would expect at least 5% of max engine power to be used overcoming friction OTOH, so possibly prop code not windmilling propellor enough? LaRCsim - uses published friction model, but can't remember offhand if rubbing friction only or rubbing + pumping. Assumes fully warm oil I think. Should port it to JSBSim. Note that both the above only cut in when engine cut since power correlation used is for shaft power - by definition it gives zero at (running) idle. Need to check the whole windmilling thing re prop and engine. Closing the throttle should increase pumping losses and help to stop the engine - is this standard procedure for a definately dead one? Cheers - Dave _______________________________________________ Flightgear-devel mailing list [EMAIL PROTECTED] http://mail.flightgear.org/mailman/listinfo/flightgear-devel
