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Old Apr 05, 2012, 07:39 AM
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Elec Motor wattage equivilant to a 46 size nitro engine

Hello everyone;
I'm still trying to get my head around some of this electric technology, and I'm also in the process of putting together a fun fly event using 46 size planes, and wanting to include electric planes into the mix as well this year. However, still being a newbie regarding electric planes, what wattage would I be looking for? I want to ensure that the electric planes will be as competitive with the nitro powered planes, but not sure where to cap the wattage to ensure that all motors are all on a level playing field.

I've been told somewhere between 750 and 1000 watts would qualify, however, to me, that seems to be quite a spread to manage.

Can someone please help me with this new world for me?
Thanks.
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Old Apr 05, 2012, 09:48 AM
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Lnagel's Avatar
Moab, Utah, USA
Joined Apr 2003
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750 Watts equals 1 horsepower. What is the horsepower rating of a typical 46 glow engine?
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Old Apr 05, 2012, 09:53 AM
Lost but making good time
Joined Nov 2008
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dak,

I'm quoting from Maxx products international, LLC. www.maxxprod.com

Sport 2 or 4 cycle...1250 W/cubic in
BB 2cycle 1500 W/cubic in
High perf, 2C/4C 1800 W/cubic in
Racing, Ducted fan 4000 W/cubic in

Multiply the displacement of the recommended engine by the Watts/cubic in rating.to find the power required of the electric motor. Example...a .40 plain bearing engine will make .40 ci x 1250W/ci = 500 watts of power.

Mild performance 50W/lb
Mild aerobatics 75 W/lb
Aggressive aerobatics 100W/lb
3D or high Speed 125-150W/lb
Competition 300+W/lb

Regards,

Hankg
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Old Apr 05, 2012, 03:01 PM
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http://www.headsuprc.com/servlet/the...tor/Categories

Look at this, maybe the specs will help you determine what you need/want.
Don
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Old Apr 05, 2012, 11:22 PM
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Thank you guys for the quick responses. Hopefully I can find what I need with this information, and if anyone else has anything to add, please let me know. I'm sure there are other's wondering the same information as well.....
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Old Apr 06, 2012, 06:13 AM
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South Wales U.K.
Joined Mar 2003
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Don't forget, with electric power you have a much greater range of props to choose from. You are not as limited by what a .46 could turn.

A bigger diameter prop will give more thrust, (at possibly reduced speed), if that is a requirement for the plane. Think about what prop the plane could best fly on, then look for a motor, (and battery voltage, number of Lipo cells), that will turn the prop.
Electric isn't easy. Often the easier route is to look in the - Glow to Electric Conversions forum - to see what others have used for the same type, size, and weight of plane.
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Old Apr 07, 2012, 10:11 PM
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I was told to use C.I.x2000 so .46x2000=920 watts
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Old Apr 07, 2012, 10:44 PM
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The high desert of Southern California
Joined Jul 2002
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What plane are you setting up? Power needs will change for say a Piper Cub, trainer or a Edge, Giles, or 3D type of plane.

Well here are a couple that are rated to be close to a 2c.46.

https://www.leaderhobby.com/product....=9394001223658

https://www.leaderhobby.com/product....=9394001223659

https://www.leaderhobby.com/product....=9394001224556

I have this motor, 5s 5000mah battery, 60 amp esc, 12.5x6 prop and it rips my Giles 202 around like a rocket.

http://www.hobbypartz.com/monsterpow...ess-motor.html




Buzz.
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Old Apr 12, 2012, 01:17 AM
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Hey guys;
Here's a little clarification of what I'm looking for: I'm hosting a 3 day sports pilot championship event that is limited to 46 sized nitro powered planes. I'm opening this up to the electric guys as well cause we have a bunch that want to fly this year, but in order to keep this competitive and evenly matched, I need to know at what max wattage to set the limit to so that everyone is evenly matched.

Part of my dilemna is this: I know one pilot who wants to use the hanger 9 sundowner 36 with an eflite power 32 motor, but at stock setups, the wattage is approx 750 watts. But according to the calculations above, this wouldn't qualify for the 600-700 watt range by the calulations listed.

However, looking at the Leader motors submitted by BLVDBUZZARD, these motors are all rated at about 1200watts, and the Monsterpower 46 from hobbypartz is showing its a 925 watt motor....... and if this is accurate, then it would make sense that the eflite power 32 motor is only 750 watts and a 46 size motor is about 1100 watts (picking an inbetween number for this)..... talk about all sorts of confusing........ ;-)........

Hopefully this makes sense and someone can help me clear the mud out of all this. I'm still trying to learn the electric side of the hobby, and hoping that after this event is done, I will definitely have a greater understanding of this.
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Old Apr 12, 2012, 07:08 PM
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Old Apr 12, 2012, 07:38 PM
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Right about say 900 to 1,000 watts should make it about equal. I do have the Monster Power 46 in a Giles 202 50. it is rated for a .462s engine. I had a YS .63 in it. I pulled it and installed the MP 46 swinging a 13X6.5 prop, 5s 5000 battery and it is really close to the YS 63.Yet I am pushing 1250 to 1300 watts.

Buzz.
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Old Apr 13, 2012, 02:45 AM
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United States, CA, Barstow
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Quote:
Originally Posted by dakoris73 View Post
Hey guys;
Here's a little clarification of what I'm looking for: I'm hosting a 3 day sports pilot championship event that is limited to 46 sized nitro powered planes. I'm opening this up to the electric guys as well cause we have a bunch that want to fly this year, but in order to keep this competitive and evenly matched, I need to know at what max wattage to set the limit to so that everyone is evenly matched.

Part of my dilemna is this: I know one pilot who wants to use the hanger 9 sundowner 36 with an eflite power 32 motor, but at stock setups, the wattage is approx 750 watts. But according to the calculations above, this wouldn't qualify for the 600-700 watt range by the calulations listed.

However, looking at the Leader motors submitted by BLVDBUZZARD, these motors are all rated at about 1200watts, and the Monsterpower 46 from hobbypartz is showing its a 925 watt motor....... and if this is accurate, then it would make sense that the eflite power 32 motor is only 750 watts and a 46 size motor is about 1100 watts (picking an inbetween number for this)..... talk about all sorts of confusing........ ;-)........

Hopefully this makes sense and someone can help me clear the mud out of all this. I'm still trying to learn the electric side of the hobby, and hoping that after this event is done, I will definitely have a greater understanding of this.
Trying to equate electric motors to IC motors based solely on watts IMHO will not work. Watts can be altered via prop diameter, prop pitch, throttle settings and battery amperage. All variables. Just as an IC plane built for a .25 uses a .40 - .46 (most IC plane boxes even list the recommended engine sizes as .25 - .50).

Use instead overall flying weight of the aircraft - AUW as your criteria. Easier to do as a fish scale and a bungie cord or two will weigh every plane on site - and they can be placed in "classes" very easily using one simple criteria. It's like most other sporting events - lightweights with lightweights and heavyweights against heavyweights.

If you are the CD - make it easy on yourself.

IC planes weigh WITH FULL FUEL LOAD and ELECTRIC planes weigh WITH the battery installed. Note props used at weigh in and away we go!

Just my humble opinion though.

Hillbille
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Old Apr 13, 2012, 09:42 PM
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Kingston, Canada
Joined Jun 2004
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A buddy and I have a Twist 3D40 sport plane. He has an OS46 FX on his. I have a Himax 5018 530 on mine. They are equal speed wide open in level flight. Mine has a little more pulling power going vertical as it's swinging a larger prop. The Himax is rated at 900 watts. So a 1000 watts would be a good number.

Gord.
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Old Apr 14, 2012, 03:28 AM
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Thank you all again for your opinions and thoughts about my questions. It looks like the consensus is about 900 -1000 watts is about the right range to use for this event. Hopefully this will all work out and things will go good for this event.
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Old Apr 14, 2012, 05:23 AM
fmw
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My .40 size P-51 flies very nicely on 900 watts. 770KV motor on 4S battery with a 13X65 prop.
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