Prop fans for homebuilts

Awesome and inovative plan Starman and great commentaries on props from the hosts of experts here. Its been awhile since I visisted and feels good to be again. I am still working on restoring my scrap Cessna 150 and after hearing soo much about props from you fellas needs to hear from you that I can make a prop for that craft right here in Guyana, South america. We great variety of wood speicies here. If not can a prop be made from fibreglass or carbonfibre( what the difference? ). We have some pretty good machining shop here and even a foundry. Can prop be forged ,casted from a mold. Please tell me this is possible. I am determind to get this bird fixed and will tirelessly use all resources that a poor man can gather in this cause. I await with arms wide open for all the comments and info you guys can give. knock me out.

Jerry

I'm guessing a wood prop would probably be the best for the first attempt. A search of Amazon or the Aircraft Spruce book section might even turn up a "how to carve your own wood propeller" title or two.

I think casting a prop is a no-no. Making a wood prop is not that hard if you follow established guidelines. There are books on the subject; for example:

Propeller Making
for the Amateur

by Eric Clutton (google it)

Originally Posted by wally

There was a huge thick aluminum plate added to the fuselage side in line with the blades - "just in case". It was pretty cool to see.

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I've always wondered if a plate like that would do any good and if it needed to cover substantial "length" because the blades would either be breaking free and headed aft or breaking free and climbing forward relative to the aircraft. ..
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An old standard metal prop that has been filed just a bit beyond limits would probably be best. You might find a runout but usable prop for free.

I don't recall if you need to comply with any rules there or not. A used runout prop would certainly be better than trying to cast your own.

Thanks BB and Pt . I,ll check out that book and where can I source a good runout prop from?

Jerry,
Is it a standard C-150 you have, with O-200 engine?
Is the plane an experimental or certified C-150?

Jan
www.jcpropellerdesign.com

I mentioned earlier here that I would show you the supersonic fan I made which was to be put on a V8 running at racing speeds.


12 blades. The hub was 18" diameter and was cut from 3/4" thick high strength T-1 steel plate. Can you say heavy?

There were formed angles made from 1/4" thick stainless steel. These were riveted to each blade and were bolted to the hub.

The fan diameter was 42". Each blade was made from 16ga stainless steel and at the root had a doubler made out of 14ga stainless. These two pieces were fused (melt welded) to each other along the outside edges, the 14ga piece was on the under side of the airfoil. No filler rods were used so as not to change the weight. The blades were cut with the angles you see rather than curves in order to have precision (they were laid out and cut by hand) The 14ga was there for the 'washer' effect and to absorb and redistribute the centrifugal force from the rivets to the 16ga.

Aluminum could not be used because the G forces at the tips was so high that aluminum wouldn't be able to hold it's own blade tips on. The stainless has much higher tensile strength but still the tips had to be tapered quite a bit for a good safety margin.



This drawing shows an end view of the blades, which were rolled up before being welded together. The straight lines are imaginary chord lines, which shows how the blades derived their twist from the root to the tip using the rolled metal. The 'airfoil' at the root had a lot of camber to prevent leading edge flow separation. This camber reduced steadily to the tips, which were flat, sharpened at the front and the back, and were perfect supersonic airfoils! The blade was held straight by centrifugal force.