E-Propeller digital pitch protractor

[seagull]

E-Props has supplied two different digital protractors over the years. Since I have two complete propellers, I decided to compare the gauges.

The smaller protractor is rechargeable and measures in 0.05° increments at our typical pitch settings. When I checked both gauges on the same propeller, I found they differed by about 0.75°, with the smaller gauge consistently reading lower.

I bring this up because it's easy to focus on matching a specific pitch number instead of matching performance. E-Props blades are very consistent, so blade shape isn't the variable. If your digital protractor reads a little differently than someone else's, you'll still end up with a similar pitch, but the number on the display may not be directly comparable.

The takeaway is that the digital protractor gets you very close, but a flight test is still the best way to dial in the final pitch for your airplane.

 

[rockyfatcat]

Since I already owned a digital inclinometer, I declined buying another when purchasing a ground adjustable prop. I ended up making my own fixture to hold the inclinometer. The directions with my ground adjustable suggest running at full power on the ground to determine the RPM at full power before flying it. They said that an adjustment of 1 degree of blade angle will change the maximum RPM BY 100, and suggested fine tuning the prop angle so the engine is at full throttle/redline on the ground.

 

[seagull]

……. and suggested fine tuning the prop angle so the engine is at full throttle/redline on the ground.

If you settle for that setting you are leaving a lot of performance on the ground.

 

[Piper J3]

I think more important is precision... Will the gage consistently give the same reading when applied under identical conditions? If the gage does not repeat, then how can you set three different prop blades to the same pitch?

When I fly my 12 with 3-blade E-prop, a convenient check of relative blade pitch is when the sun shines on the back side of the propellor. The sun “strobes” each blade, and if the frozen images align, then all three blades share the same pitch angle setting…

 

[rockyfatcat]

If you settle for that setting you are leaving a lot of performance on the ground.

That would be the initial setting on the ground before flying it. Then an additional adjustments to dial it in.

 

[seagull]

I think more important is precision... Will the gage consistently give the same reading when applied under identical conditions? If the gage does not repeat, then how can you set three different prop blades to the same pitch?

When I fly my 12 with 3-blade E-prop, a convenient check of relative blade pitch is when the sun shines on the back side of the propellor. The sun “strobes” each blade, and if the frozen images align, then all three blades share the same pitch angle setting…

Both the older and current protractors they provide are equally repeatable. The new “smaller” digital protractor will show .05 degrees which allows a more precise setting.