ORIGINAL: MarkGrabowski
ORIGINAL: flyncajun
The 18.5 12 is used primarily for noise issues.
Of the glow models at the worlds,I think Team Japans engines were the quietest.
12 pitch seems to be the magic number for that.
In my testing, However, the midrange on the 12 pitch wpn has a step feel like getting on the pipe with a two stroke and it can get fast on you quick if your not on top of it.
The 11-11.5 pitch props in the 19-19.5 range can be made as quiet and work the best overall IMHO most constant curve and better brake and speed control
particularly if you Carbon the prop and stiffen it up ( a little trick I learned from Lockhart
Your better off extending the blade for noise reduction and sticking with the 11-11.5 pitch range.
I`m not a fan of the WPN series of blades except for the 10 pitch when I was running the YS1.6
Bryan
Bryan, both you and Matt K. mention that you stiffen the prop with CF. Would you mind expanding on that a bit? Is it woven cloth or plain straight fibers and what side of the prop do u apply the cloth?
Mark,
I believe Bryan does it on the apc nylon props just like dave Lockhart does. Dave discussed what he does with me a few months ago on his electric plastic props. He uses a combination of cloth on bias and mat nonwoven carbon. He only applied it on one side but to me there is even more benefit to apply the material on both sides.
I work with wood but laminated one plastic prop for Lochowski. My wood technique is straight forward....I buy XOAR electric wood props from Chief Aircraft and remove the finish. Then I epoxy a double layer of cloth, bias cut, to both sides. The layers are stretched a bit to increase the longetudinal component. Then I trim the cloth and get the balance close by removing some epoxy.
The assembly is then inserted into a top and bottom coccon made of 010" mylar sheet, the edges are taped closed and the whole thing inserted into a vacuum bag. After curing, trim and balance as necessary. Very sprty outcome.
The wood electric props are required to save me trimming and shaping of the thicker glow/gas props. The XOAR prop has an outstanding shape very similar to apc, which to me are the best there is. The electric laminated woodies are being used in glow/gas applications. Weight wise the outcome is unequaled...a 19x8 is 60 grams and a 19x10 just 3 grams more. A 20x10 is only 80 grams and a 19x13, 75grams
After I've run some props for a few hundred flights with a little help from my friends, eventually I will write an article for Model Aviation when I get some time.
MattK