Herb Sanders wrote:

 Paul & Ed, As one who experienced a prop failure on first flight, please
allow me to make a comment. About 20 years ago at Sun & Fun I met a young
man who had built
 a Long EZ and was a graduate aeronautical engineer and was interensted in
props Ron Lueck's dad had built the Air Shark and Ron has gone on to develop
the Comp Monster line of kitplanes.

 He offered to custom build me a prop he claimed would go several knots
faster, I agreed to buy one, and he built one and sent it to me in a couple
of months. The improved efficiency was from thin blades covered in kevlar
for strength. On the first flight, I lifted off, made no unusual pitch or
yaw moves, climbed up to 1000 ft and stayed in the pattern. On the downwind
at about 140 mph I developed a vibration and it got worse as I turned base,
final, and slowed for landing.

 I landed and taxied to the ramp and a friend ran out and said my prop was
smoking. I shut down, got out and looked over the prop. About a foot out
from the center, both blades were broken chordwise and you could take the
tip and move the blades fore and aft about a foot. They were retained only
by the kevlar fabric and the smoke was from the heat/friction of the wood
rubbing together. (remember the Boy Scout trick of starting a fire rubbing
wood together) My engine was not retained by a cable and either of the
blades departing would have been fatal according to Mike Melville.

 When I was 20 years younger, I flew first flight on eight canards and did
some flight testing on new products for Sensenich Props and for Ben Ellison
on the throttle body injector. I had a total engine out from a mixture
system failure in flight and the engine went to idle cutoff - I was
fortunate to land on a paved highway in Arkansas with no damage or injury.

 The point of telling you this is that in testing, some things pass the test
and some fail. I would really hate for you to look back the next day and
think, was it really necessary to do in flight testing on the new design,
complex, high risk piece of equipment on the very first day it was ever spun
up?

 I have heard that God protects fools and drunks. Since my friend Ed is no
fool, please get him drunk if he flys this prop on the first day :-).

 I love and appreciate all that you do - just be careful.
 Regards, Herb Sanders

I would second those comments with a loud "YO". Over 50 percent of inflight
prop failures are fatal. Faster than you can think about it - the world
turns into a blur, and you are attempting to fly an extremely tail heavy
glider. Metal props are currently outlawed in F1 air racing for this reason,
Also most of the few airplanes that have landed after a prop failure were
composite construction with high strength and high damping. - Vance J

 David Stricker wrote:

Hello all,
I've been sitting here reading and thinking about the prop / flight test and
wondered if its possible to attach a vibration sensor out on the business
end of the PSRU that could cut the engine, in the event excessive vibration
was detected early on. Just thinking outside box in the interest of safety.
Dave Stricker

That might work. I think the guys are having a bit of trouble hand propping
the engine back through the gear box.

Paul Lamar



The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2002 All world wide rights reserved.