Mailing List flyrotary@lancaironline.net Message #66336
From: Finn Lassen finn.lassen@verizon.net <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: RV-4 prop
Date: Wed, 16 Sep 2020 08:55:02 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Thanks Bill.

I'll take it.

Sending you an email directly.

Finn

On 9/15/2020 9:20 PM, Bill Bradburry bbradburry@verizon.net wrote:

Finn,

It is really not too late.  Frank told me that a prop in my condition was worth $1000, but I want only $700 for it.  That includes the crush plate and bolts.  That brings the total cost of the prop down to probably around $600.  It is 76 inches long and needs to be cut down to at least 74”.  You can do that yourself.  You don’t really HAVE to get the rain edge installed.  That would save you the $700 that Frank is charging for that service.  And maybe even Ed Sterba could do it for you.  Think about it. 

 

Worst case you would have a brand new $2600 prop for $1400!  Not a bad deal anyway you cut it.

 

Bill

 

Sent from Mail for Windows 10

 

From: Finn Lassen finn.lassen@verizonnet
Sent: Tuesday, September 15, 2020 7:58 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] RV-4 prop

 

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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