Alan Coppen Posted August 16, 2020 Share Posted August 16, 2020 Hi, I am about to commence building a 1939 Dick Korda Wakefield. I want to make my own prop, and I want to make it as authentic as possible however I am unable to find a plan or drawing or in fact any info on a single bladed folder. Is anyone able to help please 🙄 Quote Link to comment Share on other sites More sharing options...
Martin Dilly 1 Posted August 16, 2020 Share Posted August 16, 2020 Outerzone has plans for several Dick Korda models, including his 1939 Wakefield winner. There seems to be plenty of prop detail here: https://outerzone.co.uk/plan_details.asp?ID=6065 Quote Link to comment Share on other sites More sharing options...
Alan Coppen Posted August 16, 2020 Author Share Posted August 16, 2020 Thanks Martin, Yes the plan does have a good detailed drawing of the prop, thank you for that info. However, I am still not sure of the way it works. Looking at the drawing I presume the blade is held by the rear hinged wire bracket, the tension of the wound motor pulls the pin into the hub against the spring, thereby driving the prop. Now what I am not sure of - does the prop stay up in the drive position on the hub purely by centrifugal force and when the motor winds down disengaging the drive pin does the blade then fold? any explanation would be helpful. Many thanks Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 17, 2020 Share Posted August 17, 2020 That's how I remember them working Alan, you hold the tip of the blade out at release and when it starts windmilling at the end of the 'power' run the airflow blows the blade back just like it does with an electric glider folding prop. IIRC rather than carving blades, sometimes we used blades laminated from 1/16 balsa and moulded round a jamjar to get the camber. The root would be built up by adding harder balsa to accept the wire pivot. Quote Link to comment Share on other sites More sharing options...
Alan Coppen Posted August 17, 2020 Author Share Posted August 17, 2020 Thanks Bob, I see it now. I am familiar with forming props from sheet balsa as I do (did) quite a bit of indoor flying, so I might try that method for the blade. Thanks again. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 17, 2020 Share Posted August 17, 2020 It occurred to me that folding electric prop blades could potentially be used though they do tend to be a bit on the slim side. Quote Link to comment Share on other sites More sharing options...
Alan Coppen Posted August 17, 2020 Author Share Posted August 17, 2020 Do you think that apart from the electric blade width, the shape and pitch would be OK? Quote Link to comment Share on other sites More sharing options...
Alan Coppen Posted August 17, 2020 Author Share Posted August 17, 2020 Do you think that apart from the electric blade width, the shape and pitch would be OK? Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted August 17, 2020 Share Posted August 17, 2020 Pitch is a geometric function so that should be ok, however they are designed for the relatively harsh startup and higher revs from an electric motor so my concern (other than a lock of blade area) would be the weight of them. Those that I've used on electric soarers are still quite light so might be worth trying as an experiment. As for shape, in my opinion that would be less important than area. You might want a longer electric blade to compensate for the lack of area to absorb the power from the motor and extend the run. One good point is that the blade should have an accurately formed and efficient section compared to a hand carved prop. At least for my carving standards it would Edited By Bob Cotsford on 17/08/2020 13:00:05 Quote Link to comment Share on other sites More sharing options...
Alan Coppen Posted August 17, 2020 Author Share Posted August 17, 2020 OK, thank you for your info, very helpful and interesting. Quote Link to comment Share on other sites More sharing options...
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