Ed and Jim's performance

X-Mozilla-Keys:

Ed Anderson wrote:


Gross weight at take off on that flight was 1575 lbs, ROC at 90 mph was

fpm.  Water Rad thickeness is 3 3/8" thick - GM Air condition condenser
cores canted at approx 30 degree to airflow set back 10" from cowl air
intake opening with fiberglass ducts forcing all captured air through
radiators.

Jim Mosur flew his RV-6 down from Canada on Thursday with Neil Kruiswky.

So

we compared aircraft and tried to account for my lessor performance

compared

to his.  With the two of us on board at same climb airspeed he was

getting

over 1000 fpm compared to my solo climb of 700 fpm.  My aircraft is

approx

120 lbs heavier, but with two in Jims that was more than accounted
for.  I turn approx 100-200 more rpm than he does during the same flight
regime.  His pitch is 74 mine is 72 but as anyone knows comparing pitch
between two different prop makers is not reliable. However, that could
account for my engine turning slight more rpm.   In any case, the cord

of

his prop is approx 6 1/4 inches while the chord of my prop is 5 1/8".
Clearly don't know if that would make that kind of difference in
performance, but it was the only thing we could come up with.  I set my
timing differently today and will go out and fly it tomorrow.

Ed Anderson
Matthew NC


Tracy Crook wrote:


Thanks for the comparative data Ed, this kind of stuff is hard to find.  I
was surprised at the numbers though.  My RV-4 is a bit lighter but the
difference in performance should not be that much.  Last week on a rare 75
degree, 60% humidity day I did some ROC tests and got 2100 FPM at 100 MPH.
This was solo at a gross takeoff weight of 1220 pounds, engine rpm 5300 rpm,
WOT,  prop  68 x 71.  This was starting from an altitude of 100 ft. above
MSL.

You mentioned it once but I've forgotten what your empty weight was.  Also,
what was your WOT rpm during the climb?   You might want to try using a
slightly higher airspeed.  I find that mine is best around 100 - 110 mph.
The higher speed allows the engine to turn up more rpm and the increase in
power more than makes up for the increased drag.

Tracy



The Aircraft Rotary Engine Newsletter.              Powered by Linux.

http://home.earthlink.net/~rotaryeng/            http://www.linux.org