An old standby in a modern world

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Postby Thurman » Sat Dec 29, 2018 10:46 am

There is an earlier thread here about how to make a p-30 half-tube for winding outside the model. Good information! Now I am charged up to build a system including a couple new stooges and the Piserchio claw hooks. I notice you can buy them for Wakefield (aka F1B) and Coupe D'Hiver (F1G). What I cannot find is what these Hooks weigh.

Weight is always a challenge for a durable, warp-free P-30 design. The hooks for a (say, 12 strand .125) Coupe would have to be designed for at least three ties the torque/tension of a ( 4 strand .125) motor which I mostly use. My amateur materials and methods cannot match the strength to weight levels achieved by the professional shops that make them. But I would like to know where the bar is set for a professional Coupe Piserchio Claw (even though it is overkill for my requirements).

Since the consensus seems to be that professionally made P-30 Claws are not available, I would still appreciate the weights of store boughts and weights achieved by other home-made Claws. I have been working almost full time for a week using my El Cheapo Chinese mill, lathe, hobby shop aluminum and Hardware Store aluminum hardware. Several dozen failures/losses. No wins good enough to weigh..but I am guessing over two grams. Heck, my transmitter weighs less. But no, I did not build it.

Thanks, Thrman

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Joined: Sun May 19, 2019 7:12 am


Postby lincoln » Sun May 19, 2019 7:47 am

I guess you've probably solved your problem by now. If not, I should think you could make up something similar with music wire soldered to a brass tube. Or maybe gluing an aluminum tube to the wire would solve the problem. Or have a little bobbin in the middle, loose. Music wire is far stronger than aluminum, so it might even weigh less. For instance, 3 inches of .047" wire ought to weigh 0.7 grams. 3 inches of 1/16" wire ought to weigh 1.2 grams. If you try this, you may want to leave a bit of extra wire on each end to make the bending easier. You can cut it off and smooth the ends later.

This isn't based on specific experience with p-claws, but just from messing around with music wire in the past. Those claws look like a good idea. With a little bobbin in the middle of the claw, it might act like the wobbly peg that some scale guys use. And be a lot easier to install.

For the real weight weenie, I suspect a claw made from carbon fiber tow might be lighter, and easier to make as well. I may have to try that.

However, I'm thinking a freewheeling arrangement might allow the motor to unwind enough that the claw fell off the peg. The FAC, in it's wisdom, bans props that fold in flight. I suppose there are other ways to set up the nose to deal with that and still allow freewheeling.

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