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Ok, got out today and fired up the engine with the
new prop and gear box. This is the 76x88 inch prop that is 2" longer than
the one Tracy and Rusty have on their birds. The static was 5400 rpm at
28.75" with ambient manifold pressure reading 29.75" (as best I
interpolated). OAT was 87F. Idle was considerably smoother whether
due to increased mass of larger prop, new gear box or both. I did notice
the 2.85 has considerably less gear lash than the 2.17.
I took it for a quick taxi up and down our
35' wide runway and notice that the "P" effect was considerable at full
power. It felt like someone was taking the nose of the aircraft and
forcefully shoving it to the left. Rudder with Nose wheel helping kept
things under control without any problem, but I think my first full power
takeoffs will be where they have those 100 -150' wide runways - just to be
safe.{:>). Subjectively seemed to have considerable more
acceleration but will not do any definitive test on this runway.
Temperatures were normal. After extended
runup the oil temps approached 190F and coolant temp got up to 210F this is what
I would normally see. Considering that the static rpm was the same as my
old gearbox and prop, it likely I was producing the same HP and therefore would
not expect major difference. The larger prop did not seem to interfere
with the cooling airflow - at least on the ground.
The RPM is a bit less than I had hoped for
- but may just indicate that the 2" increased diameter over the ones flying
now (74x88) is a bit more prop than is optimum. I will fly with it and
record the data so that Performance Propellers will know how much to trim when I
ship it back.
Hope to get the spinner painted over the weekend
and go flying early next week.
Ed
Ed Anderson
RV-6A N494BW Rotary
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Matthews, NC
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