Prop pitch for pusher ULS

Re: Prop pitch for pusher ULS

by Roger Lee » 7 years ago

Roger Lee

131 5.38k 5.44k

Your 5600 - 5650 is a good balance for the new prop to. Since it is a different prop may may have to set static on the ground for approximately 4600 - 4700 and then go fly. Then tweak the final pitch to get your in flight rpm you desire.
I never care about what the actual pitch number is because it can change depending on how a person does it and where he does it.
15 - 16 is as good a place to start as any then do a static run and then your flight if all seems good. When I did my prop research project years ago each prop was a little different. All you really care about is the final result.

---

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

Re: Prop pitch for pusher ULS

by Eugene Klimenko » 7 years ago

Eugene Klimenko

12 74 1

Ok, I did 16° and went for short flight this morning. Didn't had time to do anything more. At full power airplane was climbing at 4700 RPM. So, I landed right away.

So, next time I should try with 15 1/2°, or 15°?

Target is about 5200-5400 on climb? And 5600 WOT in level cruise. Correct?

Re: Prop pitch for pusher ULS

by Eugene Klimenko » 7 years ago

Eugene Klimenko

12 74 1

Found my answer! Thank you!
- "A prop getting 5200 on take seems a little under pitched and would get upwards of 5800 at WOT in level flight. Nothing really wrong with that. That gives you a good climb prop, but you would lose some speed and fuel economy. In other words you'll have to give it more throttle and rpm to do a decent cruise speed which in turn would eat up more fuel. Most guys are around 4950-5000 rpm at takeoff and that usually puts them in the 5600 range, Adding a little pitch back into the prop will also increase temps a small amount. Probably not much in your case." -

Re: Prop pitch for pusher ULS

by Eugene Klimenko » 7 years ago

Eugene Klimenko

12 74 1

Did little video test to see airflow in to my new propeller. Doesn't look very good, for sure!

https://drive.google.com/open?id=18mSCARsph_s0xgMjd1GxvgVFlrccX7pl

Re: Prop pitch for pusher ULS

by Eugene Klimenko » 7 years ago

Eugene Klimenko

12 74 1

Set prop for 14° this morning, went flying, but still can only get 5420 WOT in level flight.

70" prop vs 60" prop for sure big difference on pitch setting, but so far I am going slower at 5000 RPM by about 8 MPH.

Less vibration this time = must be prop related problem.

I will try with 13° next time.