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Setting Ground Adjustable Prop

RGaines

Well Known Member
Are there any guidelines for setting the prop. My is set at max course (cruise). Take off rpm is 4860. Single pilot rate of climb is 1500 to 1700 fpm dual pilot is 900 fpm. At full throttle I am able to get 5300 rpm max at 3,000 ft.

Should I be able to get 5500 rpm? Anybody have any ideas of what is optimum or is it just personal preference?

Thanks
 
Are there any guidelines for setting the prop. My is set at max course (cruise). Take off rpm is 4860. Single pilot rate of climb is 1500 to 1700 fpm dual pilot is 900 fpm. At full throttle I am able to get 5300 rpm max at 3,000 ft.

Should I be able to get 5500 rpm? Anybody have any ideas of what is optimum or is it just personal preference?

Thanks


There is a suggested static RPM when completing the production acceptance check list. My experience has shown that a full throttle static RPM of 4950-4975 is a good compromise for most flight conditions in the RV-12.
 
I would suggest 5000 RPM static to start with and adjust from there based on flight test. A good target would be for about 5400 RPM @ level flight, WOT and low DA. I normally throttle back in cruise to 5000-5200 where the fuel burn is about 1 gpm lower, noise is a lot lower, and you loose only 2-3kt; pretty sweet trade.

I wouldn't worry about inadvertently exceeding 5500RPM in decent because remember, redline is 5800, you're allowed to exceed 5500 RPM for up to 5 minutes at WOT.

Also, don't set the RPM too low, if you'll stress the engine. And if you burn 100LL, you need to cruise no lower than 5200 RPM to keep temps up to help lead from accumulating in the engine.

TODR
 
SL-912-016 was issued by Rotax a few months ago.

It recommends that all operations at high manifold pressure (take-off power) be at an engine RPM of at least 5200.

All rotax owners should register at this site http://www.rotax-owner.com/.

You can set up your profile so that you receive e-mail notification of any service letters, etc, that are issued.
 
Rotax Owners

Scott is right. The most recent one mentioned looking for trash in the carburetors. Wondering if that had anything to do with Van's recommendation to stop using TCP with AVgas LL?
 
The pitch cylinder on my prop limits the adjustment from about 3-1/2 to 4-1/2 on the hub indicator. Is that all the adjustment that is allowed for this application or should the adjustment allow from 1-5 as the instructions indicate ?
 
The pitch cylinder on my prop limits the adjustment from about 3-1/2 to 4-1/2 on the hub indicator. Is that all the adjustment that is allowed for this application or should the adjustment allow from 1-5 as the instructions indicate ?

There is a plate in the hub that limits the travel to 3 1/2 to 4 1/2 on the scale of the hub. So others know, this is just an arbitrary set of numbers to use as a starting point for pitching the prop. If you adjust one blade the other one moves with it, very accurately I might add. Any more pitch and the prop is too course for the power of the engine, any less and the engine will over spin. The prop is set up for this application and works great.

The mechanics in the prop are very accurate to keep both blades pitched the same. I checked mine with a prop protractor and it was within a 1/4 degree.
 
Last edited:
Richard,

I just went through that exercise. Had close to the same numbers as you with the prop set at the coarsest setting. I made all of my adjustments with the Warp Drive prop protractor and was able to set the pitch of both blades within a two tenths of a degree of each other. Here are my notes.

Before any blade adjustments, with the blades at the coarsest blade setting, the static WOT rpm was approx 4700 rpm.

Adjustment #1. I first measured the blade pitch from coarsest to finest and that measurement was 4 degrees as limited by the limiter plate in the hub. As a first adjustment, I set the pitch of both blades to the midpoint. I was now 2 degrees from the coarsest setting. That gave me a static WOT 4980 rpm. The PAP says we are to shoot for 4870-4930 rpm. So I was a little high. With the blades in this position, in the air, WOT rpm was near 5700 rpm. 5500 rpm is max continuous for the Rotax.

Adjustment #2. I went back 0.4 degrees toward the coarsest setting. After the oil warmed to 125 degrees the static WOT was 4920 rpm. In the air, WOT rpm was 5500 rpm. After landing with the engine oil hot, the static WOT rpm dropped to 4880 rpm.

Will leave it here and decide in the spring if I want to change it again.

Hope that helps. ..marty

A tiny bit of an adjustment changes things a bunch.
 
I sure like this engine prop combination. Very smooth combination at cruise, adjustable for different applications, good looking prop.
 
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