Easy speed mods question

[pierre smith]

Mornin' everybody. Since we're building these RVs to go fast, I'd appreciate info on some easy speed mods. I've been told that guys have faired the lower motor mount tubes to avoid turbulence there and also cut off the exhausts to be more or less flush with the bottom cowl. Others have added a radius to the lower firewall area (like the RV8) to smooth airflow and reduce drag.
Is there a source for some of these speed mods with documentation on what is really gained?
Pierre Smith

RV6A close to finishing
180HP 3 bladed Catto

[chuck]

Not RV specific but it has lots of good information about speed in general.

Speed with Economy by Kent Paser.

http://aviatorbooks.com/speed-with-economy.html

He raced is Mustang II and got a very large speed and efficiency improvement on a plane not too much unlike an RV.

Chuck

[penguin]

I would recommend against cutting down your tail pipes as short tail pipes create a lot of vibration through the floor. It the kind of vibration that makes your foot get numb after a half hour resting on a rudder pedal, and the kind that makes passengers want to bring a large lump of foam to put their feet on. My experience is that the pipes should make around a 25 degree angle with the bottom of the fuselage to minimize the vibration, and should be left at the length Larry Vetterman supplies. I did not see any loss in speed when I fitted regular length pipes.

How about elevator & rudder gaps seals as easy go-faster mods?

Yours, Peter