Folding props for rubber power

Free flight and rubber powered models
jackdaw
Posts: 157
Joined: 16 Feb 2018, 20:30
Location: Wet and Windy North Wales

Folding props for rubber power

Post by jackdaw »

Last built a FF rubber powered model 60 years back, KK flying scale. Am getting into this again, with RC(light weight single cell and one servo on rudder). But, have been looking for info on making folding props(for 30" - 40" wing span) without much success. Details on other aspects like winding tubes etc also needed. Anyone got any links for this info so I can truly regress?
TIA
Stewart
Posts: 36
Joined: 17 Feb 2018, 04:57

Re: Folding props for rubber power

Post by Stewart »

You need to look through some of the vintage rubber plans for folding props, just found this in the Korda Dethermaliser plan.
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jackdaw
Posts: 157
Joined: 16 Feb 2018, 20:30
Location: Wet and Windy North Wales

Re: Folding props for rubber power

Post by jackdaw »

Thanks for that. I've got the basic idea, I was hoping there may be a few articles on the design criteria for such systems ie spring strength on prop shaft compared to pull of rubber holding stop lever away from stop, angle of hinge line, etc. IIRC this sort of thing was a common topic for articles in AM many decades ago. I'll keep searching.
pulserudder
Posts: 21
Joined: 21 Feb 2018, 02:01
Location: North Carolina

Re: Folding props for rubber power

Post by pulserudder »

This might have some of what you're looking for especially towards the second half. There was also a thread on RCG maybe a few years ago in the free flight forum on carving larger props, by BMathews, I think...

David

https://youtu.be/6bsaf5-4QlE
Twitcher
Posts: 49
Joined: 16 Feb 2018, 12:17

Re: Folding props for rubber power

Post by Twitcher »

If you want someone to make a complete folding prop assembly for you, incudiing the correct noseblock for your chosen model, I know a man who'd do that. His price for non-folders is about £1 an inch. More for a folder, obviously.

What you get for your money is a beautifully carved balsa prop, covered in glass cloth, with all necessary fittings, prop shaft and bearing tubes.

Although I've successfully carved my own balsa props, I'm sure his are far more efficient than mine!

PM me if you'd like his phone number.

The spring from an old ball-point pen does a good job on the mechanical stop thing. And as for winding tubes (a.k.a. blast tubes), if you're only intending to do sport flying, you don't really need these. I therefore normally never wind beyond 60-70% of maximumum winds, which is very conservative and unlikely ever to result in a blown motor. It's only if you're winding for maximum turns - e.g. in a competition - that you really need these things.

David
jackdaw
Posts: 157
Joined: 16 Feb 2018, 20:30
Location: Wet and Windy North Wales

Re: Folding props for rubber power

Post by jackdaw »

Thanks everyone. I'd like to try and make my own prop and hub (for better or worse). Thought of using one of these prop kits https://www.vintagemodelcompany.com/127 ... ubber.html or https://www.vintagemodelcompany.com/17- ... ubber.html to get a feel for the carving. Plus, I could copy the outlines onto my own wood for further props. The more I see the more I'm getting a feel for what is required. A bit of experimenting should see something workable in the way of a folding prop and hub. I'll use the nose block and plastic props supplied with the kits for starters.
I'm only going to be doing 'sport' flying, I'm not at all competition orientated. I've posted in a few other threads about covering options and light weight RC with rubber power. It's all part of this 'thing' that took my interest after I decided to do some 'sticks and tissue' modelling as a form of rehabilitation after my stroke last year. The idea took hold after our clubs winter build club meeting when some of the free flight proponents submitted their models, with RDT and single blade folding props, for judging. To that end I bought a KK Ace and KK Gypsy from the reissued Ripmax range. My vision, which the stroke affected, is about 95% OK. But, for close/detailed work I still have to turn my head to the right and look out of the left side of my vision to avoid the blank/distorted areas in my right of center vision. Hey Ho, what fun when trying to solder small wires for the RC :? .
Once again thanks for the responses.
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Phil_G
Posts: 465
Joined: 15 Feb 2018, 23:32
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Re: Folding props for rubber power

Post by Phil_G »

Hi Allan, I have a copy of Peter Holland's book "Model Aeroplane Building" and chapter 19 is all about making rubber props. Shall I send it to you? (to keep) it wont scan without breaking the binding.

The Peterborough Club site is where the FF experts seem to hang out Allan:
http://www.peterboroughmfc.org/
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jackdaw
Posts: 157
Joined: 16 Feb 2018, 20:30
Location: Wet and Windy North Wales

Re: Folding props for rubber power

Post by jackdaw »

That's very generous of you Phil. Let me at least pay for the postage if you are happy to donate the book. Would PayPal be OK for a 'gift' of the required 'beer tokens''?
Stewart
Posts: 36
Joined: 17 Feb 2018, 04:57

Re: Folding props for rubber power

Post by Stewart »

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