We have an engine that will make 250
 HP.
 Target speed for an RV4 is 225 MPH.
 We intend to race this airplane.

 We think a 4 blade Warp Drive will absorb the HP.
 What is the maximum twist angle change you can obtain
 by tapering the blades. I know the twist is less then
 theoretically ideal. We are willing to accept that
 as the features of ground adjustable and carbon
 construction
 make the Warp Drive unique and better in the field of
 props.
 IMHO that outweighs the less than ideal theoretical twist
 distribution.

 I know you lose blade area as the twist is increased and
 the tip cord is reduced. What taper do you recommend?

 I would like to see a twist angle plot verses the blade
 radius for the taper you recommend.

 This I think is ideal theoretical twist distribution for
 231 MPH.
 Radius in feet.
 ----------------------------------------------------
 MPH = 231.8
Radius...Circ MPH....Cord MPH...0 Angle of Attack
0.3.........48.2........236.8......78.26
0.5.........96.4........251.1......67.42
0.8........144.6........273.2......58.05
1.0........192.8........301.5......50.25
1.3........241.0........334.4......43.89
1.5........289.2........370.6......38.72
1.8........337.4........409.3......34.50
2.0........385.6........449.9......31.02
2.3........433.8........491.8......28.12
2.5........481.9........534.8......25.69
2.8........530.1........578.6......23.62
3.0........578.3........623.1......21.84

 Twist = 56.41    Ratio Twist/Root = 0.72   Ratio Twist/Tip = 2.58

--------------------------------------------------------------------

 Paul Lamar

This sounds like an ideal application for a Paul Lipps type
propeller.
The Phantom biplane has won a Reno with his 3 and later 4
blade props.

http://www.eaa.org/experimenter/articles/2009-02_elippse.asp

Erik


Is Paul Lips selling blades?

Paul Lamar

Paul Lipps designs and Craig Catto builds them.
Erik

Anybody have an email address for Paul Lips?

Paul Lamar