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My Feedback: (3)

DOES ANYONE KNOW OF THE EXISTANCE OR IF ANYBODY MADE A 4 OR 3 BLADE PROP HUB FROM SCRATCH..... BY JUST CUTTING A PROP IN HALF AND BOLTING IT TO THE HUB??????? I'M TRYING TO MAKE ONE, AND NEED SOME IDEAS
THANKS

BMatthews

I'm surprised no one else posted the answer to this.


DO NOT DO THIS ! ! ! ! ! !

By cutting into the hub area to overlap the blades you are severley weakening the most critical part of the prop. The long fibers of the wood or plastic mass that you are depending on to resist the centrifugal forces of the engine at full power are basically cut in half and what remains doesn't even line up with the forces so it's even more weak. The world's strongest glues are not as strong as the material you remove so that isn't the answer either.


If you want multiblade props then get the ones that are made for the job.


The only time I would consider such a mod to be OK would be if you're making up a multiblade prop for a gear reduction electric where it'll be running at 1/3 at most of the original designed RPM. Even then I'd keep folks back away from it until it had proven itself.

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My Feedback: (3)

http://www.zingerpropeller.com/4_bladed_propeller.htm CHECK THIS OUT.... I JUST FOUND IT.... IF THEY CAN DO IT ....I CAN DO IT.

BMatthews

That's a whole different kettle of fish. Look at those plates in the hub. They've designed this to properley support the stubs of the prop blades. You didn't say that in the first post. Just that you wanted to cut out the hubs to allow you to cross laminate them together.

If you do try this be sure to overbuild the hub plates. Use decent alloy heat treated stock for the plates and be sure it's thick enough to take the loads. How thick depends on what you're using it for. I'd go find some of the Zinger ones to get an idea of what they did first. You'll also need to incorporate a center spacer to prevent the prop nut from collapsing the pates together. And let's not forget that you need to buy one whole prop for each blade so that there is enough meat in the hub to prevent splitting from the screws that go through. And PLEASE don't tell me that you'll just cut through the middle of the hub to make two blades. That would be risking way too much. It's very easy to split the grain of the hub and shed a blade that way.

Just be aware that this is VERY DANGEROUS ground you're walking on. A blade that sheds at full rpm can easily cause serious injury or death. And I am NOT exagerating on this one. Every prop should be tested by starting at idle on at least the size of engine you 're planing on using it on and then only after stepping well behind the arc should you rev it up to full rpm for a good long run. And no spectators for at least 30 feet to either side just in case. Finally be sure to inspect for cracking in the wood or plastic at the hub or stressed blade bolts after every flight for at least the first couple of dozen flights. If it makes it past that then you're probably good for the long term.

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My Feedback: (3)

I'M USING 7075 T6 AVIATION GRADE AL., THE BOTTON PIECE IS 1/4" AND THE TOP IS 1/8" THE CENTER SPACER IS 1/128" LOWER THAN THE BLADES, I'LL TRY TO TAKE SOME PICS TODAY TO SHOW U GUYS