Wooden Propellor

Does anyone know of a propeller manufacturer, or chap in a shed, who could make me a bespoke 28 x 10 prop? The problem I'm having with off the peg versions is the hub diameter and boss thickness as it needs to fit a WW1 rotary engine. I can supply a suitable piece of laminated walnut if required. Thanks.

mick

Is the prop for static demo or does it have to survive power runs ?

Emgee

Was that you asking over on MEM? if not there are some links in this thread

Why have you chosen walnut ? I live down the road from RATIER who have been producing full sized propellors for more than 100 yrs and they have a museum. I haven't seen any walnut props there. Acacia/oak, mahogany and of course composites and Al alloys.

The Walnut Propellor Company

en.wikipedia.org/wiki/Hartzell_Propeller

Useful article on wooden propellor construction here, suggests walnut may be better than mahogany. Certainly looks nicer

Neil

Hello mick, if you want to make your own propellor it is not really too difficult, i speak as one who has done so in my former life as an aircraft inspector. Walnut and Maple is a very good combination to use, and much hard work is saved by cutting and glueing up the laminations in a staggered fashion rather than a rectangular bulk of timber. See if you can find a copy of the propellor making book by Fred Clutton, use our friend Google or enquire at the Light Aircraft Association for both the book and/or one off makers.

Trevor

Canadian Hard Maple is a very good choice for Wooden props as well. Find some with straight grained will make a great prop.

Hi. Jason. Yes I am he, but for some reason that trail suddenly went cold, he did say that he had over three months work to get through till he might have a window. The prop is to fit a running engine. Thanks for the input.

Beech if you want to save money.

Martin

Here's a link to one of a multitude of 28x10 wood props for sale, just an email or tel call will get the hub dimensions

**LINK**

Emgee

Presumably Mick's prop needs a hub big enough to use several studs on a PCD rather than a single hole through the middle.

Regarding suitable woods; it is, perhaps, worth bearing in mind that American oak, walnut and maple are all different species with different properties to those grown in the UK. Similarly "mahogany" covers an enormous variety of similar looking but otherwise unrelated species - There are no EN numbers in the timber trade!

Cheers,

Rod

Definitely agree, and although this prop is not going to propel a piloted aircraft, then the timber should still be selected with regard to grain slope, knots, pitch pockets, shakes and so on before the wood is laminated so as to be reasonably sure that the completed item stays together. The glue should be of a high standard standard, prefereably something like Aerodux or an epoxy and not any old pva or old bone glue as a 1/5 scale rotary will still be able to generate a respectable level power and torque. A disintegrating 28" prop would be rather dangerous.

Is your engine the Blackmore Bentley BR2 mick ?

Trevor

Hi. Trevor. Its definitely a BR2, but of mixed parenthood!

I've spent a couple of months trying to source a prop sympathetic to the original engine and to that end I have contacted numerous suppliers both here and overseas about the sizes of the boss, but the diameter and thickness of the boss was always too small, so I don't intend to compromise the appearance of the engine by using the wrong prop and so I need to find a chap in a shed that's prepared to make one.

Edited By mick on 15/03/2018 17:44:46

mick ,

p.m sent,

Trevor

Have you tried the props made for the big engines from 3W, they will take a 28x10 or more and have a multi bolt fixing much like the BR-2 on the smaller engines and the bigger ones that look like they use a knurled flange actually have a 63mm bolt PCD so should have a bigger hub than you need.

As an altenative to an epoxy, you could use one of the foaming PU glues e.g. Gorilla Glue - very strong when used properly.

Rob

It might be worth looking at such sites as Midland Paramotors Ltd www.midlandparamotors.com/propellers/wooden/

Ian S C

PU glues are indeed very strong adhesives when used correctly, but are certainly not suitable to use in the construction of a functioning propeller due to the fact that they are foaming adhesives and so the cured glue line is interspersed with micro bubbles. The constant and cyclic flexure and vibration of the prop blades when the engine is running and transmitting power would eventually lead to glue line failure and delamination and disintegration. Even model size props, and this is for quite a large scale engine generating considerable power, flex a lot when running

They're quite okay just an ornamental prop though.

Trevor

A friend who has designed and built a 7 cylinder radial engine, says that he sourced his prop from China.

Howard