Mailing List flyrotary@lancaironline.net Message #66335
From: Ernest Christley echristley@att.net <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] RV-4 prop
Date: Wed, 16 Sep 2020 12:45:30 +0000 (UTC)
To: Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net>
Laminating would is not that difficult.  Match the grain.  Sand it to cut the wax off.  Use too much glue and clamp with rubber bands.
After the prop is carved, lay on enough layers of fiberglass that you never worry about the reliability.

On Tuesday, September 15, 2020, 8:58:29 PM EDT, Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net> wrote:


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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