"Kent, Russell" wrote:

Paul Lamar wrote:

The big problem when it comes to aerobatics is finding a gear box

that will accommodate a hydraulic constant speed prop. We are just
not there yet and as I understand it an electric constant speed prop
does not change pitch fast enough for aerobatic use. I could be
wrong so check with Hoffman or MT. On the other hand it does not
hurt the rotary to overspeed to 10,000 RPM so this may not be an
issue. A piston engine will hand grenade if over speeded to that
extent.

The engine may not be the speed limiting component.  How's an MT or
Hoffman going to like spinning at 3500 RPM? (10,000 / 2.85)  Let's
see, centripetal force is F = mv**2/r.  Since m and r are constants
for our theoretical engine & prop, the force on the blade goes as the
square of the (rotational) velocity, and increases by a factor of
3500**2/2400**2 = 2.13 (i.e. 113% greater).  It is my understanding
that props have relatively tight safety margins...

Russell Kent

I think the FAA requires a test at twice top RPM or about 5,800 RPM as I
recall.

Paul Lamar

Matt Prather wrote:

Any problem with a turbocharger surviving G's and tumbling?   I can't
recall whether this Pitts was to be NA or not.

Regards,

Matt-
VE N34RD, C150 N714BK

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