I'd settle for 3 or 4 slow revolutions of the prop before it spins up to MicroSoft's 500 rpm minimum for ignition.
Actually we did this for the A-26, but I can't remember if we released it or not. We did the whine and the slow revs for 9-10 blades I think. Also, probably 12-13 blades for a 4-prop engine and 9 for a 3-prop engine, i.e. 3 full revs.
EDIT: Yes, we did this and it is part of the A-26. Doug Dawson did the work. This is in the documentation folder if you wish to activate it. See no reason why it wouldn't work for the F7F. I will try that Friday.
The A-26B/C Invader for FS2004 (general compatibility with FSX)
INSTALLATION FOR FS9 ONLY
To activate the engine start gauge, remove the // from window00 gauge 31
and ensure you have the latest FSUIPC installed (3.74, as of April 2,
2007,) available here:
http://www.schiratti.com/dowson.html
Version 3.7 is the earliest version which the starter gauge will work with.
-------------------------------------------------------------
Optional FS9 Engine Start Gauge Notes:
The included optional A26_engine_start.gau from D. Dawson has been
modified so the engines can be started using the overhead panel.
Speaking of which, that is a two step process. First engage the desired
engine, then click and hold the starter switch for that engine.
The engine start gauge can be engaged in spot view either by pressing
<Ctrl><e> to automatically start both engines in sequence, or by
following the standard keyboard commands to start the engines individually.
Regarding compatibility, the startup gauge will only work with FS9. It
will not work with FSX or with FS2002.
The sound gauge will not work with FS2002, but will work with FSX, and
is digitally signed for use in that sim. Commenting the sound gauge out
of the panel.cfg for FS2002 compatibility will not affect the working of
the panel, beyond the loss of the energizer sound.
In both cases, use of these gauges in unsupported versions of FS will
result in crashes to desktop.
---------------------------------------------------------------------------------------
Doug Dawson
The A26B/C Invader SOH Project Team
March 2007
http://www.sim-outhouse.com/sohforums/forumdisplay.php?f=49