[Flightgear-devel] JSBsim and low rpm engines (AN-2)

[Joacim P. <no...@tu...>]

On Wed, 8 Nov 2006, Yurik V. Nikiforoff wrote:

> Yes, It works, but I can't set diameter of propeller by data sheat from flight
> manual. Engine can't start, if I set propeller greater then 110'. But real
> AV-2 propeller have 136' diameter.

Found this kludge in JSBsim:
FGPiston::doEngineStartup()
in src/FDM/JSBSim/models/propulsion/FGPiston.cpp,
line 351 and on:
 	if (!Running && spark && fuel) {  // start the engine if revs high enough
 	    if (Cranking) {
 	      if ((RPM > 450) && (crank_counter > 175)) // Add a little delay to startup
 		Running = true;                         // on the starter
 	    } else {
 	      if (RPM > 450)                            // This allows us to in-air start
 		Running = true;                         // when windmilling
 	    }
 	  }
and further down:
 	    } else if ((RPM <= 480) && (Cranking)) {
               Running = false;
             }


So engine parameters are hard-coded in JSBsim...
But there is a min rpm setting in the engine definitions -- that ought to be
used here.

Isn't there another aircraft model that can't idle properly? I think it is
either the Spitfire or the Mustang. It stalls if it's left on idle too
long.