[prev in list] [next in list] [prev in thread] [next in thread] 

List:       flightgear-devel
Subject:    [Flightgear-devel] B1900
From:       David Culp <davidculp2 () comcast ! net>
Date:       2003-08-28 16:01:44
[Download RAW message or body]

> Has anyone thought about building a B1900 model for flightgear?  It
> would be nice to have a really well done twin turbo (3d model, flight
> model, engine model, prop model, cockpit, sounds, animations, etc.)
> and I think this would be a great candidate.

In order to accurately model a turboprop we'll need a new turboprop engine 
module.  Right now we can fake it in JSBSim by using a turbine which puts out 
less thrust as speed increases (see the OV-10).  We can also fake it by 
connecting a prop to a turbine (see the Fokker 50).  These work fine for now, 
but real turboprops need automatic fuel control and prop angle control, which 
don't yet exist in FG.  Most turboprops operate in one of two modes, CONSTANT 
SPEED and NORMAL (which are actually called different names by different 
manufacturers). 

In CONSTANT SPEED mode the engine turns at a constant high rpm ( ~ 98%-100% ), 
and the power lever controls prop pitch.  In this case the fuel controller 
increases fuel flow automatically to maintain rpm. This mode is used for 
takeoff, landing, or aerobatics, where instant power response is desired.

In NORMAL mode the power lever controls both rpm and prop angle.  The fuel 
controller and prop controller automatically make the optimum adjustments.  
This mode is used for cruise.

All this is a level of complexity far above the current turbine and propeller 
models, and it may be best to have a seperate turboprop model which takes 
care of the turbine, fuel control, prop control and prop.  In the mean time 
the fakes work pretty well.

-- 
****************************
David Culp
davidculp2@comcast.net
****************************

_______________________________________________
Flightgear-devel mailing list
Flightgear-devel@flightgear.org
http://mail.flightgear.org/mailman/listinfo/flightgear-devel

[prev in list] [next in list] [prev in thread] [next in thread]