Wrathall Mark wrote:

Snip>BTW I just talked with Tracy Saylor and he now claims well over 200 HP.
He has made some improvements in his engine and will run in next years Sun
100
at Sun&Fun. He is also replacing the tail on his RV6 as it is a mass of
cracks.
Dave Anders has been through two tails on his RV4 so far.

I admire these guys for their acheivements, but thing it is pretty
iresponsible the way the EAA holds them up as heros for their speed without
telling the whole story about the increased vigilence which the associated
risk increase requires. None other the Sport Aviation articles ever
mentioned either of these guys having structural problems with their
airframes.

Mark Wrathall

It appears all RV4's and RV6's are affected. It just seems to happen faster
with a metal constant speed prop, more HP and faster speeds.
The large four cylinder direct drive engines are horrendous when it comes to torque
pulses. With a given HP the torque pulses applied to the prop on a geared rotary 
are half as strong and 2.17 times as many per rev as compared to a direct drive
four cylinder piston engine.

Notice also in the below chart the torque on a two rotor does not go negative
unlike the four cylinder piston engine. The legendary torque pulsations of
the rotary are another urban myth. Nothing could be further from the truth.
Tracy is seeing no cracks at all on his rotary powered RV4.

Paul Lamar
 
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