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Engine basics => Engine set up tips => Topic started by: Robin_Holden on October 05, 2009, 01:46:21 AM
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Greetings all from S.W.France. Need some advice please .
Flew my Banshee yesterday. It's got a Byron Barker modified Tower 40 installed , a really lovely engine modified by a real ' gent '. It was swinging an MAS 10X6 on 62 foot lines.
I took along my stopwatch and gave my wife the task of recording my lap times.
I launched in a four -stroke at 9,500 and recorded a lap time of 5.6 seconds. This was a tad too slow for me as I'm a pretty ancient 're-tread' as you call them in the U.S and prefer someting a touch quicker especially when it's windy.My piloting skills are pretty abysmal sadly !
My question is : With the above information , what RPM do you think I should launch at please ?
I've tried other props' by the way and my Tower 40 seems to prefer this set up.
My apologies if this seems a really daft question but coming back to C/L after a long lay off [ working ! ] means a lot of catching up.
Much obliged as ever for any contributions ,
Robin [ ex-pat Brit in the Charente full of ex-pat Brits ]
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If the engine is "happy" with the prop/rpm you mentioned, you might shorten the lines a bit. Figure "about"
0.1 second of lap time per foot of line length................
Cheers,
Jim
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I agree with Jim. If the lines are really 62 foot lines--eyelet to eyelet, going to 58 foot lines would be perfect for a Banshee I would think. That would get you to ~5.2 sec or so--maybe still a little slow, but if your engine is doing the 4-2-4 dance, maybe that is ok.
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I found a Supercool 11 x 5 Petalblade to give me the best results with a Tower 40. An 11 x 5 Zinger was almost as good.