Prop Angle vs RPM and Speed

[Spook712]

Hello , I have a Kitfox 4 Speester with a 912 Engine and a Warrp Drive Prop.
At the moment I´m cruising with 5000 - 5200 RPM and that gives me under 100 mph ( around 90 most of the time ).
What are the experiences with that combination and would it help to increase the pitch of the prop. GND RPM is just around 5000 at the beginning of the take off.

Cheers Marc

[MotReklaw]

On the two Rotax 912S engines I owned, I set the ground max runup to about 5400 rpm. That would enable me to run at 5800-5900 (which I rarely did) in flight.
If I remember correctly we were at something like 13-15 degrees on the prop.
I think your maximum inflight rpm is a little low.

Others probably have more experience, it's been a while....

[DesertFox4]

What kind of tachometer are you using? Check that your tachometer is accurate. We have run into low reading Rotax tachometers many times. Your speeds seem slow for an 80 hp. Speedster. Usually an 80 hp. Speedster with strut fairings installed and all the Speedster mods will cruise easily at 110 mph. at 5200 to 5400 rpms.

[Av8r3400]

I have a 68" Warp 3-blade, three blade, tapered tip, nickel inlay prop in front of my 80 hp 912UL on my round cowl, Model IV-1050.

At 5400 I show 110-115 mph.
At 5000 I show 100-105 mph.
At 4500 I show 90-95 mph.

These are in calm, smooth conditions.

I can get 5200 at a 60-70 mph climb out.

I've never done a full power static run, so I can't say for sure, but would estimate that I would get 4900-5000 rpm.

[phintz]

If the weather cooperates this weekend will be the first time i'll have my series 6 in the air. My rotax mech. told me to set the static RPM around 4950. I set the prop at 18 degrees to get almost 5000. This seems low to me but would like a second opinion.

Thanks Patrick
series 6 , trigear
3 blade warp drive prop
phase I testing

[jdmcbean]

Patrick!!! Congrats and be careful.

Static RPM of 5000 will be a good starting point at your altitude. We usually target for 5150-5200 static.

[phintz]

Patrick!!! Congrats and be careful.

Static RPM of 5000 will be a good starting point at your altitude. We usually target for 5150-5200 static.

I backed off the pitch 1 Degree, this should give me 5000 or better. Will do another static rpm run up before first flight. Really windy here today!

Thank you for the input
Patrick