The plans say to set the prop pitch full on the initial installation. I followed this instruction, but after torqueing the bolts I referred again to the hub index marks and it looked like they had moved a little. I let it go. My static rpm was 5200, and the first test card indicated that I had ferocious take off and climb (for 83 cubic inches), but was only seeing 102 knots in level flight at 5500 RPM, with enough throttle left to overspeed the engine. My prop was definitely underpitched.
I contacted Van's for more advice on pitching the prop, and found out that Scott will have an in-depth article in the next RVator of their experience with this prop and how to adjust it. Scott also made a fixture of scrap alum angle that contacts the trailing edge and back of the blade and then uses a digital level to measure the blade angle.
I took Scott's idea and modified it a bit to come up with my version of the MPPF (McDaniels Prop Protractor Fixture). This little fixture contacts the trailing edge of the blade and the back of the blade in 3 places and uses Scott's sighting notch to line up with the paint strip on the front of the blade.
Scott, I hope you don't mind me going on like this about your idea, but it really is a good one.
[url=http://tonytessitore.smugmug.com/RV-12-Project-N577RV/RV-12-Tools-Work-Fixtures/7992519_GYr3k#910442110_Yp9n6-A-LB][/URL]
I found a nice little digital level on the internet for $24.99 and it even has a tripod screw attachment so I could bolt it to the MPPF:
[url=http://tonytessitore.smugmug.com/RV-12-Project-N577RV/RV-12-Tools-Work-Fixtures/7992519_GYr3k#912340962_fMNUT-A-LB][/URL]
Here is the protractor in use:
[url=http://tonytessitore.smugmug.com/RV-12-Project-N577RV/RV-12-Tools-Work-Fixtures/7992519_GYr3k#913401658_rpfgo-A-LB][/URL]
I found the device to be repeatable to about 0.1°. And, I found my blades to be 1° different from each other! That is way too much. The Sensenich instructions say to set the blades within 0.25° of each other if you have a protractor. I was able to readjust the pitch and set the blades to within about 0.1° of each other.
I am now getting 115 knots at 5360 (without pants), and the engine will not pull more RPM in level flight, so I may be slightly over pitched. I think I will leave it this way for a while until I get more time on the motor, then make a final adjustment.
So, it looks like that small amount of adjustment we are restricted to by the stops in the hub are ideal for this aircraft. But, the hub index marks are rather crude and you need a protractor to do the job well.
Thanks Scott, for your great idea, and I am sure everyone will be looking forward to the next RVator.
Tony
I contacted Van's for more advice on pitching the prop, and found out that Scott will have an in-depth article in the next RVator of their experience with this prop and how to adjust it. Scott also made a fixture of scrap alum angle that contacts the trailing edge and back of the blade and then uses a digital level to measure the blade angle.
I took Scott's idea and modified it a bit to come up with my version of the MPPF (McDaniels Prop Protractor Fixture). This little fixture contacts the trailing edge of the blade and the back of the blade in 3 places and uses Scott's sighting notch to line up with the paint strip on the front of the blade.
Scott, I hope you don't mind me going on like this about your idea, but it really is a good one.
[url=http://tonytessitore.smugmug.com/RV-12-Project-N577RV/RV-12-Tools-Work-Fixtures/7992519_GYr3k#910442110_Yp9n6-A-LB][/URL]
I found a nice little digital level on the internet for $24.99 and it even has a tripod screw attachment so I could bolt it to the MPPF:
[url=http://tonytessitore.smugmug.com/RV-12-Project-N577RV/RV-12-Tools-Work-Fixtures/7992519_GYr3k#912340962_fMNUT-A-LB][/URL]
Here is the protractor in use:
[url=http://tonytessitore.smugmug.com/RV-12-Project-N577RV/RV-12-Tools-Work-Fixtures/7992519_GYr3k#913401658_rpfgo-A-LB][/URL]
I found the device to be repeatable to about 0.1°. And, I found my blades to be 1° different from each other! That is way too much. The Sensenich instructions say to set the blades within 0.25° of each other if you have a protractor. I was able to readjust the pitch and set the blades to within about 0.1° of each other.
I am now getting 115 knots at 5360 (without pants), and the engine will not pull more RPM in level flight, so I may be slightly over pitched. I think I will leave it this way for a while until I get more time on the motor, then make a final adjustment.
So, it looks like that small amount of adjustment we are restricted to by the stops in the hub are ideal for this aircraft. But, the hub index marks are rather crude and you need a protractor to do the job well.
Thanks Scott, for your great idea, and I am sure everyone will be looking forward to the next RVator.
Tony
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