PROP PITCH

[kiwilad]

I have just recieved a new 3 blade 70 inch Warpdrive prop.I want to fit it to my 503 Windlass ,1-3.47 e-box.What I'd like is a starting point to set the pitch too. Thanks

[Morph]

cruise speed 50mph

cruise rpm 5500

prop rpm = 5500/3.47 = 1585 rpm (round up to 1600)

Check this chart (http://www.hoverhawk.com/propspd.html) give you a pitch of about 33 inches (this is what is stamped on the blade in the case of fixed blades)

Use this convertor (http://www.indoorduration.com/PropCalc.asp) Distance from hub to prop tip = 72"/2 = 36",

Unfortunately the calculator is arse about face, i.e it asks for degrees and gives you the result in inches. But if you start from the bottom and work up it comes to 8 to 9 degrees of pitch will give you a cruise of 50mph at 5500

Then run your static tests. Put the nose of the trike against a wall or hangar etc, clear everybody away and run the engine at full taps, brakes on. Don't over rev, i.e. no more than 6800rpm. You ideal should be between 6250 and 6400.

If it is reving too high, increase the pitch a little at a time. If reving too low. decrease the pitch

hope this helps

I haven't tested this in a real environment yet, picked it up off the Warp website so I can't vouch for the accuracy

PS have you jetted the carbs for your altitude?

[Morph]

oh yes, and the other thing is first measure what angle the prop is at when installed on the plane. Simply take the protractor and place it agains the prop hub, rotate the inner circle until the spirit level is in the middle and read off that degree setting. Then add or subtract the starting degree from that to increase the pitch

[Mogas]

I would try about 12 degrees and work from there.
Its been a long time but I seem to remember my 3 blade warp on my 503 liked 11 degrees.
Happy tuning.

[kiwilad]

Thanks Guys,That will get me started. Morph-- will check jetting next time carbs are off, the previous owner was flying from sea level (same as here ) and it runs very smoothly,so I'm assuming that it is jetted correctly.
One more question,I've read two variations of where to measure the pitch degrees - one says at the tip,the other says at 2/3 of the prop length.Where do I measure it ?

[Oupa-G]

Does not really matter as long as it is always measured in the same place. Then your angles may differ from somebody else . The Warp blades are so accurate that it does not really matter but your revs as Morph said are the important thing.

Cheers Oupa-G

[kiwilad]

12 deg at the prop tips has given me a static of 6330 rpm.I'm happy. Thanks again guys

[Duck Rogers]

12 deg at the prop tips has given me a static of 6330 rpm.I'm happy. Thanks again guys

Now go fly the damn thing and stop fiddling...

[kiwilad]

But fiddlins half the fun