Can remember P factor.
Seneca 11 had counter rotating props.
In the theory, there was no critical engine for VMCa.
In the practice, the loss of the left engine, No1, was slightly more critical than the loss if the right.
Refresher...
Conditions for determination of Vmca.
Aircraft in take off configured.
Critical engine not fethered.
Other engine full power.
Cof G at max aft position.
Sea level.
MAUW.
Indicated Vmca decreases with altitude.
So, Vmca demo in PA30 can be quite bad when stall speed reached at same time as Vmca.
These are the more thoughts for your appreciation.
The Gannet had counter rotating props also - both on the nose spinner.
Last edited by Der absolute Hammer; 26th September 2008 at 16:14.
Reason: Error to be corrected.