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Jul 08, 2012, 06:48 PM
The tattoo guy
Greasetattoo's Avatar
Discussion

What electric size motor would be equivelant to a 15cc motor?


Title pretty much says it all:

What electric size motor would be equivelant to a 15cc motor?

Any ideas, anyone?
thanks
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Jul 08, 2012, 07:01 PM
Registered User
I dont know anything about engines but a O.S 95AX (15.55cc) produces 2.86hp at 15000rpm (manufacture specs) which is 2133W which would be produced by a 711g motor.

So i would say a power 160 or any 700g or there abouts motor would be equivalent to a 15cc engine.
Jul 08, 2012, 07:04 PM
The tattoo guy
Greasetattoo's Avatar
Wow, thanks for the super fast reply..

What motor would you recommend or come close to at:
www.hobbyking.com?

Any idea?
Jul 08, 2012, 07:10 PM
Registered User
The OS95AX is a 2-stroke. OS FS95V is a 4-stroke 15.59cc and that produces 1.68hp at 10000rpm which is equal to 1253W which would be produced by a 418g motor; so something like a . power 60 (380g) or power 90(450g) motor
Jul 08, 2012, 07:12 PM
Registered User
what plane is the motor for
Jul 08, 2012, 07:17 PM
The tattoo guy
Greasetattoo's Avatar
Actually, for a paraglider...
Powered parachute.

10' foot parachute.

The engine that was on it:
RCGF 15cc engine
Last edited by Greasetattoo; Jul 08, 2012 at 07:19 PM. Reason: added more..
Jul 08, 2012, 07:23 PM
Registered User
The turnigy G160 is the equivalent of the e-flite power 160.
Jul 08, 2012, 07:37 PM
The tattoo guy
Greasetattoo's Avatar
Thanks Bajinuk,
appreciate your help.


I found another good thread here too:
https://www.rcgroups.com/forums/show....php?t=1562822

They recommend the 160 too!
Nov 26, 2012, 07:41 PM
Registered User
RC Erik's Avatar
Actually 15cc is equal to a .91 cubic inch engine/motor

And the Power 160 motor is equal to a 26.2cc engine.

At least that is what I came up with doing the conversion.
Nov 27, 2012, 02:51 AM
Registered User
After 4 or 5 months I'm guessing it's sorted but as with all of these things it really helps if people say EXACTLY what they're talking about.

E.g. it took a while to get to the fact that we were talking about an RCGF 15cc....which is a petrol/gas engine so a) it is heavy and b) it delivers a lot LESS power than either 2 or 4-stroke glow engines. There's almost no chance of getting anywhere near even 2hp (1500W) out of it so I'd guess any low Kv motor of around 1000-1200W would do it. Power 160 would be silly. Power 90 would plenty and, as bajinuk says even a Power 60 would probably do it. I wonder what Grease ended up with .

Steve
Last edited by slipstick; Nov 27, 2012 at 07:10 AM.
Nov 27, 2012, 10:25 AM
Registered User
machinate's Avatar
I haven't been around much lately, and missed this. Here's my take on electric power systems to replace glow and gas:

When it comes to replacing an existing glow or gas engine, ignore the sizes. There's so much variation in engines that "15cc" barely means anything, and electric motors are available in so many configurations that just randomly picking something with similar power won't necessarily be a good match to the airframe. The best way to do it is with power-to-weight ratios. Weigh your plane without its engine, then add the advertised weight of each battery and motor you're considering. Take the power that setup can provide, and divide it by the weight:

<50 W/lb: Mostly unflyable.
50-75 W/lb: Able to sustain flight from a hand launch. Climbs will be very gentle and full power will be required for much of the flight.
75-100 W/lb: Able to perform ground takeoffs and perform basic aerobatics. May need to dive for speed before some maneuvers.
100-150 W/lb: Capable of nearly any maneuver from level flight.
150-200 W/lb: Capable of sustained vertical climbs and "3D" aerobatics.
200+ W/lb: A sane and appropriate level of power. . .
Nov 28, 2012, 05:15 AM
Jack
jackerbes's Avatar
Quote:
Originally Posted by Greasetattoo
Title pretty much says it all:

What electric size motor would be equivelant to a 15cc motor?

Any ideas, anyone?
thanks
A rule or thumb for glow fuel to electric conversions that seems to work well is this:

2000 x glow displacement in cu. in. = electric power in Watts

So for the .15 it works out that a 300W motor would be about right.

And if you like rules of thumb you can go one step further, divide that result by 3, and that is the weight of an out runner motor in grams. That is because average quality out runners can handle about 3 Watts per gram when running at their continuous rating.

I recently learned here that in runners can generally handle a higher continuous input power than out runners. For those, 4 or 4.5 Watts per gram is not out of the question for average quality motors.

Jack
Nov 28, 2012, 07:11 AM
Registered User
It's good job this was a few months ago....a 15cc motor is .91 ci not .15 ci (2.5cc) and the motor in question is gas not glow. The answer may be useful to someone else but it's probably not much help to the OP .

Steve


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