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YS45 on Arrow 40

Old 12-22-2012, 04:47 PM
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Default YS45 on Arrow 40

I am using a YS45 in a MK Arrow 40 pattern airplane. This is a very clean airframe and I'm getting around 125mph using a 10x9 APC and 10% fuel and tuned pipe. My question is:
Can I get more speed using less pitch and/or more nitro? The faster this thing goes the better it is to fly!
Thanks,
Ed
Old 12-23-2012, 07:04 AM
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Default RE: YS45 on Arrow 40

You will pick up more speed with more pitch. WHat RPM are you turning now with the 10x9? More nitro will give you a more power so you would be able to turn more pitch at the same diameter. I don't race so that is all the help I can give you for this, maybe Jimmy can weigh in here with some thoughts.
Old 12-24-2012, 09:04 AM
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Default RE: YS45 on Arrow 40

I don't have a lot of experience with the YS 2 strokes, but I believe this motor should run fine on 20% nitro. If the motor likes the 10x9, then as you add Nitro you can "up" the prop size. As Pete has stated, what RPM are you currently at? I would advance in slow increments. For racing I like to keep the 4 stroke motors in their power band. As you go up in pitch, you could also go up in diameter as well. The 45 manual states 2000-18000 RPM and a 11x6-11x7 prop. If using a 10x9 the load would be very similar to a 11x7.

The first step in the process is to see what current RPM you are getting, then you can play with Nitro, pitch, and length. Being that you are flying with a tuned pipe, you will need to see how the motor unloads with each application. Keep us all in the loop and let us know how the testing goes. (I think this is the funniest part of the hobby)

As for the original question. Less pitch, more nitro and more speed. My belief is not. If your plane is currently running at top efficiency with pipe/fuel/prop combination being used, then a reduced load with increased nitro will take the pipe out of tune.

Again, I am not a two stroke expert, and have very little experience with the tuned pipes.

Good Luck and Report back,
Jimmy Skids
Old 12-24-2012, 04:04 PM
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Default RE: YS45 on Arrow 40

Just back from flying.
14,480 rpm static with the 10x9, 10% nitro. SAME rpm with 15%.
Forgot my GPS but it unloads like a beast in the air. Judging from GPS-checked speed on other pattern plane yesterday it is doing around 140 mph or more.
Maybe a colder plug and 20% nitro for more speed?

Another improvement might be changing to a non-silenced pipe or a 10x10

In any case, this thing rocks!

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