Peter Hills 1 Posted February 9 Share Posted February 9 I would like to replace my current 2 blade 12x6 prop with a two blade folding prop achieving a similar watts output. I’m using a BL2820/07 motor and with a 12x6 prop I recorded 290watts drawing 27A, which is just about enough for reasonable performance of my Spitfire weighing 3.1lb, my spinner is 55mm. To make landings easier I would like to consider a folding prop but which size. Please can someone advise me what size folding prop could achieve a similar output. Thanks. Regards, Peter. Quote Link to comment Share on other sites More sharing options...
Shaun Walsh Posted February 9 Share Posted February 9 Running the numbers through propCalc shows very little difference between fixed and folding blade props so a 12x6 folding Graupner or Aeronaut prop would be a good place to start. Quote Link to comment Share on other sites More sharing options...
Brian Cooper Posted February 9 Share Posted February 9 Be careful landing a Spitfire with a "dead" propeller. . They appreciate a draught over the tail. It will be easier and a lot tidier with the motor turning the prop. 3 Quote Link to comment Share on other sites More sharing options...
J D 8 Posted February 9 Share Posted February 9 Can not see how folding prop can fold correctly on a scale Spitfire nose profile. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 9 Share Posted February 9 Most folding props are designed to be used in glider types that have a relatively small nose profile. . You would have to make sure the blade folding hinge line was outside the diameter of the spinner. Then as J D 8 points out how well will a folding prop cope with the Spitfires nose profile. Quote Link to comment Share on other sites More sharing options...
PeterF Posted February 10 Share Posted February 10 Presuming you have a hand launch Spitfire, I have a Ripmax one with 12" diameter prop and have not had any issues breaking props over 15-20 years, just make sure power is off before touching down. I do not have the brake set on the ESC so the prop is windmilling on touch down and it stops on first contact. If the brake is set and the prop stops with a blade pointing down then that can lead to breaking a blade as the brake tries to hold the blade in position. As noted above, with the shape on the bottom of the spitfire nose, a folding prop will still sit proud if it stops when pointing down. As you will need a larger than typical spinner, you may need a slightly smaller prop because setting 12x6 blades on a 60mm hub will give you a prop disc more than 12" . 1 Quote Link to comment Share on other sites More sharing options...
leccyflyer Posted February 10 Share Posted February 10 Like Peter said, a folding prop really isn't necessary for belly landing a Spitfire and the risk of breaking a prop blade is typically over estimated. Yes, it does happen, but not very often. A 12" prop on a 3lb Spitfire - assumed to be 42"-45" span at that weight - will be at slightly increased risk over the 10"x7" and 11" x 7" props that are common on such models, but it's nowhere near the stage where you break a prop every other flight. Quote Link to comment Share on other sites More sharing options...
Peter Hills 1 Posted February 11 Author Share Posted February 11 Thanks to all those who replied. After taking on board the comments I think I will stick with my existing prop and make sure the brake is off. 3 Quote Link to comment Share on other sites More sharing options...
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