-------------- Forwarded Message: --------------
From: keltro@att.net (Kelly Troyer)
To: "Paul Lipps" Subject: Re: Elippse Propeller
Date: Sat, 10 Dec 2005 07:54:00 +0000

 Paul,

  Thanks for the info and suggestions......I have e-mailed Grand Aero for info on

your blades with the numbers for my a/c , engine , etc....

 

Thanks again,

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

-------------- Original message from "Paul Lipps"

Hi, Kelly!

    I don't make props, I only design them. I have designed a prop blade for Grand Aero that will be used in a three-blade, ground-adjustable hub. It's been designed for the RV-series of planes, and will easily accomodate 150hp-200hp for cruise speeds in the 170 mph to 220 mph region. One thing I might caution you about, though. You mention only turning 2100 rpm because of your gear ratio. Takeoff with the prop adjusted for that low a cruise rpm would require a fairly high blade angle. The blades would be stalled over a large portion during the early stages of the takeoff run, and so would not give much initial thrust, making for a longer takeoff. If possible, you might consider a different gear ratio allowing you to set the blades at a lower angle, giving much better static and takeoff thrust. The three-blade prop on my Lancair turns 2230rpm static, 2440rpm in a climb at 115mph IAS, and 2800 rpm at 201 mph cruise at 10,000' dalt. This should give you an idea of the range of rpm you will get with a fixed or ground-adjustable prop. Check out Grand Aero's web site, www.grandaero.com , and if you like what you see, drop a line to John Moyle at john@grandaero.com. If you get Jack Cox's excellent magazine Sportsman Pilot, you can read about all of the race results at Reno, and the two biplanes that came in 1 & 2 with my three-blade design. www.sportsmanpilot.com .   Paul