Turboprop FDE design: propeller start-up speed?

[microlight]

Hi all,

Can I ask for advice from the prop/turboprop gurus out there?

I'm designing a FDE in FS9 for a large passenger turboprop, and one of the last things left is to get to grips with the speed of start-up of the props.

In real life, the props on this particular plane start rotating quite gently, and gradually build up speed over 25 seconds or so to get to operating speed. In FS, I've used the default King Air as a basis for the FDE design so that on startup, the props are spinning up very quickly, taking about a quarter of the time to get to speed than they should. I've amended the prop MOI figure but all that it seems to do is to affect the time it takes for the props to stop spinning after you turn them off.

Any advice?

Many thanks,
Martyn

[garryrussell]

It's one of those things FS doesn't do well

This is why you don't see any turbo prop start animations work as they should.

They will always appear to start like a piston engine.

You're stuck with it I'm afraid.

Garry

[microlight]

Thanks, Garry. I've juggled the spool-up time parameter in the .air file with the fuel flow, propeller MOI, static thrust and horsepower parameters in the .cfg file to get something that's half-reasonable. The issue is essentially that because the .air file spool-up time setting controls spool-down as well, then if you set a realistic spool-up, it takes huge amounts of time for the propellers to stop when you turn them off!

Thanks for the reply.

[DaveSims]

One of the many shortcomings of MSFS modeling of turbine behavior.  I also don't like how the turbines start and rev up.  In real life, they just come up to idle, not surging to double the N1 of idle.