Dave - Why do you feel that you have a prop limited redline? and

what is

that value?  Sonic?  structural?
By the way, there was a structural failure of a Lamar Demuth prop on
a Lancair out of Camarillo several years back that was seemingly
related to an imbedded lead balancing weight - do you know anything
about that - Vance>

I had nothing to do with it :) Vance.... that is Aymar Demuth!!!

http://exp-aircraft.com/vendors/pagesVen/AymarDeMuth.html

Paul Lamar

That is a self imposed limit on the prop.  A nice round number of 6000
engine gives me 2765 at the prop.  I arrive at this number through a
conversation with the prop maker.  It went something like (with a

southern

accent) "Well, you can run it as fast as you want, but if you run it

real

fast it might break."

At first I was a little disgruntled, but then I realized that he has no

real

way of knowing what it will withstand.  Wood does not necessarily grow

to

tolerances set by some standardization committee.  He went on to say

"Some

racers have run our props as fast as 3300, but I don't recommend that.

It

could probably withstand 2700 continuous, maybe 3000."  So I decided on

a

number that was closer to "probably" than "maybe."

I am also a little surprised with the vibration produced.  Nothing worse
than a Lycoming, but not better, which I expected.  So for now the limit

is

6000.  I have tried to have the prop balanced but the schedule keeps

falling

through.  Maybe after it is balanced I will allow occasional bursts up

to

3000 prop.

I had not heard of the failure in the Lancair.

But no bother.  I'm a "Rich Doctor" (almost an oxymoron lately). I'll

have

that C/S electric MT (or perhaps the LAEV???) within a couple of years.

Dave Leonard (just glad to be in the air whenever I want)

The Lancair owner reported very smooth operation prior to failure
and a significant loss in top speed when he replaced it with an
MT this may reflect that he was overspeeding with the fixed
pitch prop - tho several serious speed runners are reporting
lower top speed with the MT compared to metal CS props
Vance

 
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