Ed Anderson wrote:

Hi Paul,

    New topic for the group.  How do you tell if you have a "stalled Prop"
on static run up.  I know if you start take-off roll and as speed picks up
the engine loads up and the rpm drops then you probably had a "stalled
Prop". But are there indications sitting still?

   The reason I would like to know is that my newly rebuilt 91 is turning

my

prop (same prop specs/make as Tracy uses) 2670 rpm (5800 engine rpm).  Old
engine turned static at 5000-5100 rpm.  I took out a prop tach this AM and
it and the engine tach were in agreement to within the eyeball resolution

of

the engine tach (100 rpm).

   If this is indeed a reflection of the HP the engine is producing then
great, but if the rpm has increased because the prop is "stalled" then I
would like to know that if possible before first take off.  I figure
somebody on the list may be able to answer the question.

Best Regards

Ed Anderson

You got me there Ed. Sounds like you need more pitch if your engine is
strong
enough to turn that prop at 5800 RPM static. BTW I will bet your exhaust is
less
restrictive than Tracy's so you have more power. I also think your intake
manifold is better. Your engine is also ported is it not Ed?
I hope you can run your airplane in the Sun 100 this year.

Paul Lamar

Seems like if the prop was stalled, you would not get nearly the expected
static thrust. Do you need lots of brake to hold it?

Chuck Dunlap

Good idea Chuck. Get a large spring scale and measure the static thrust.
A garage door spring will work if it is calibrated. Tie it to a large tree.

Paul Lamar
 
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