Mailing List flyrotary@lancaironline.net Message #66333
From: Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net>
Subject: RV-4 prop
Date: Tue, 15 Sep 2020 20:58:03 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>

After sending the below, Ed Sterba replied:

"I'm not sure I will be able top make you a prop at this time.  I don't use a duplicating machine, all props are hand carved and I'm getting older and having difficulty carving the bigger ones.
Ed"

So there goes my plan for a $650 prop.

Performance props are now $2,700 according to Bill B. They want $700 to finish his prop (that's normally included in the price). I paid $875 in 1999 for my RV-3 Performance prop, so that 300% inflation. That's going to bust my $20,000 budget.

Any ideas for a cheaper prop?

I was thinking about building a prop duplicator and duplicating my RV-3B prop (or Tracy's RV-4 prop if I can borrow it). But where does one get 4 3/4" prop blanks or wood? Not sure I trust my ability to laminate wood...

Finn

Installation will be quite similar to Tracy Crook's RV-4.
Here are some of his notes [from https://web.archive.org/web/20111120073159/http://rotaryaviation.com/renesis_engine.htm]:
"Clark at Performance Props was very honest about the difficulty in getting the proper pitch at the blade root (out to ~ 3" past the 13" dia. spinner) with pitch this high. [88" ?]
Other conclusions are that anything less than 74" L prop is a waste on the -C [2.85:1] drive.
I must emphasize that in order for this to work [2.85:1 gear reduction instead of 2.17:1], the prop must not only be long but has to have a good profile as far down toward the root as possible with the MUCH higher pitch.  I worked with Clark at Performance Props and emphasized this.  It required a thicker than standard [4-3/8”] hub to get close to what was needed.
If you don't do these things, all you get is significantly higher rpm,  less performance, higher fuel burn and higher wear.  Tracy"


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