Please keep the realism!

[IvanK]

Great Video on the Tiger Moth. Some observations.

Tacho gyrations certainly are wild after start. With Flex/Direct drive tachos I would anticipate some fluctuations on start as the drive "takes up the slack" of going from 0 RPM to whatever the throttle position/ Idle would be. Same goes when rapidly selecting idle. These Tachos tend to exhibit more "bounce" at the lower RPM settings. If the drive cable is frayed and or damaged then fluctuations tend to be more evident. (Source Chief engineer of Flying museum in Aus).

Taxying again bounce is pretty wild in the vid.... no idea why unless terrain is affecting it ?

On Take off the tacho is pretty steady with variations of perhaps +- 50 thats all. these increase a little during acceleration as the RPM increase with increasing IAS, but again pretty small

In the cruise (3:56 in the vid) again very small bounces in the order of +- 50 RPM max.

On Final approach around 600RPM the bounce is again very small+-50 RPM.

So the vid shows wild gyrations on startup but at constant power settings and IAS pretty small variations.

Similar variation is seen in Blenheim MKIV tacho. At idle the tacho "bounce" is around +- 70 RPM but in flight including reasonable large speed excursions during a display RPM variations are only in the order of +-20 RPM. This with Pitch set to coarse. There is some great in cockpit Blenheim IV video in this DVD:

http://www.flyingmachinestv.co.uk/DV.../DVDStore.html

With respect to Merlins (Source: Chief engineer Restoration/Flying museum in Aus). RR Merlins were all Mechanical Direct/Flex drive tachos. Packard Merlins were Electrical.
Again talking to current Spitfire pilot flying RR and Packard Merlins he couldnt see any difference Tacho wise just steady RPM with virtually no bounce.