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OS 108 equivalent

Old 09-26-2005, 04:17 PM
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roydefiant
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Default OS 108 equivalent

Is there a brushless high performance electric that will pull a 15 x 8 propellor as well as this engine. I am thinking about replacing the engine with an electric in a 80 inch wingspan me 163. Thanks
Old 09-27-2005, 01:23 PM
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Matt Kirsch
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Default RE: OS 108 equivalent

Sure there is, except the setup will probably end up twice as heavy and twice as expensive as it needs to be to fly that plane every bit as well as that OS 1.08 does. HUGE efficiency gains can be had by spinning a larger propeller at a lower RPM.

First question is, why a 15x8 prop? Is it a clearance issue, or are you just looking for "similar" performance?

Second question is, how much does the plane weigh?
Old 09-27-2005, 06:47 PM
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Default RE: OS 108 equivalent

A 15 x 8 prop at about 10,000 rpm is what is fairly standard for an OS 108. The airplane is an 82 inch wingspan me -163 komet and pobably weighs around 12 - 14 lbs. Obviously since this was a rocket powered aircraft the smaller prop one can hang on the front the better it will look especially if one can use an electric and keep the cylinder head from sticking out. I'm kicking around whether it is worth trying to do as an electric.
Old 09-27-2005, 10:21 PM
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Default RE: OS 108 equivalent

Once the prop starts spinning, it practically disappears anyway, so is prop diameter really all that important? I say this because rather than spin a 15x8 prop at 10,000, you can spin a 17x10 at around 6500 RPM with an electric motor, and get the same performance.

This is a pretty tall order... 14lbs will need about 1400 Watts. Let me sleep on it.
Old 09-29-2005, 09:31 AM
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Default RE: OS 108 equivalent

I have done more homework on this plane. The plane will weigh in at 9 to 10 lbs with a 91 4 stroke engine and an 82 inch wingspan. If I went with an AXI 4130 motor with a 14 x 10 prop would this be powerful enough? What would weight of the batteries be for this motor?
Old 09-29-2005, 09:27 PM
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Default RE: OS 108 equivalent

You'll want at least 900 Watts to power this plane properly. 20 NiMH cells, or a 6S LiPoly, at 45 Amps.

A 14x10 prop on the 4130/16 will come up a little shy, though a 15x10 will put you right in the ballpark.

Using Kokam 3200 cells the pack will weigh about 21 ounces.
Old 10-08-2005, 08:47 PM
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Default RE: OS 108 equivalent

I did buy the 4130/16 axi and an apc 15 x 10 electric prop. I will be using li poly batteries, something that will equal a 24 cell pack. I am going to try and keep the weight at 9 lbs or less. Thanks for your help Matt. Is there a speed controller you would recommend. Enclosed is a picture of my JU 52 with laser 4 strokes. Roy Maynard, eden prairie, MN
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Old 10-09-2005, 10:14 AM
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Default RE: OS 108 equivalent

A 24-cell NiMH pack is roughly equivalent to a 7S LiPoly.

Take a look at the Castle Phoenix HV controllers. I'd recommend the Phoenix 85HV. The Jeti Advance Plus 77 is another option.

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