stunthanger.com
Engine basics => Engine set up tips => Topic started by: Robin_Holden on November 14, 2009, 12:22:40 AM
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Greetings fellas from a rainy Charente in S.W. France. Advice needed please .
I'm just your ordinary Sunday sport flyer , non-competitive ...... Too old , lousy pilot !
Can I ask , what would you expect to be the launch RPM using a Stunt tuned 40 [ OS FP / Tower ] swinging an 11 x 5 prop' ?
My 'planes are a mixture of the usual profile Twister / Banshee variety. Around 36 oz ready to go .
I'm using 62 foot lines , 23% lube' in the fuel [ 17%/6% ] , uniflow Dubro plastic tanks.
Very much obliged for all your comments ,
Robin [ ex-pat Brit in the Charente full of ex-pat Brits ]
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Robin I have a twister with a fp40 with a11x5 zinger prop launch at 8800 to 9000 rpm I use 5% nitro 23% oil
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Sig Champion...10% nitro at 9600-9700 rpm
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Alan , Ty and Gene ...... I'm very much obliged for your contributions.
Can I ask please , are you using 'straight' , un-modified engines OR have they been modified internally ?
Most I can get from my modified engines is around 8,500 on various 11x5 props'.
Suppose I could try upping the nitro' content to 10% like your goodselves.
Many thanks again ,
Robin.
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Robin,
For the heck of it I would try to load the engine with a bigger prop--either go to 12" or perhaps a 3 blade 11".
If the internal guts are limiting you to 8500 rpm on the ground, then let that rpm turn a bigger prop. At these lower rpm's, the engine has more time to pull in a full charge mixture, and so can probably turn a bigger prop. I guess if it tries to run faster, it can't breathe enough air/fuel to supply the power to turn the prop.
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I'm very much obliged to you guys for your advice.
Good of you , kind regards from a very 'muggy' Charente.
Robin.
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Robin -- I am using a "Tom Dixon" modified FP 40 - I don't know all he did to it but it runs smooth like a sewing
machine and has a nice 4-2-4 break - I'd try upping the nitro to see if that would help.
Gene