FYI, Virg

Hi Rene,
Just wondering if the guys over Kr-net do any pull test and compare

numbers

with each other to kind of establish a workable prop/h.p. range? Last

week
i

saw a guy testing is 601 with a couple of pulleys, a rope and an oil

cylinder

with a pressure gage attached to it. He tied one pulley on the back of

his

machine, the other to a secure tiedown point and he floored it. He got

a

reading of 350 lbs. He told me that the contraption was passed down

from
owner

to owner in the region so as to build a data base for comparison from

witch

they could draw educated guess about their set up.Any ideas???

The danger in  putting too much emphasis on static thrust is
you can under pitch your prop and when it comes time to fly the HP
will not be there. Happened to a guy down in Phoenix about
a year ago.

Paul Lamar

This is **extremely** dangerous.  Even the Wright bros. understood this.
At OSH I was looking over a report on their prop design, and they
specifically stated that static thrust measurements were very deceiving
since the air inflow velocity is zero, completely unlike the actual
flight condition.   The slower the airplane flies, the closer to useful
static thrust is, so for a 25 mph ultralight it might be of some
slight value.  For a 150 mph KR, it is dangerously useless and very
misleading.

Bill Freeman
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor

 
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