View Full Version : .65 equals how many watts??

01-18-2007, 08:07 AM
Hello everyone,

Just wondering if someone knows what a .65 glow engine puts out in watts? Thanks in advance.


01-18-2007, 10:08 AM
BD, there are allot of variables in this type of conversion, as a basic conversion from glow (power) to electric (watts) deals with a performance factor that you set.

The link below has a good description.

hope this helps:


01-18-2007, 01:36 PM
I would estimate a two stroke glow engine of that size at about 1000 to 1200 watts realistically when propped for sport use with a normal muffler. One horsepower=746watts.

I qualified my statement with "realistically" because advertised horsepowers of most glow engines are highly inflated by the importers and distributors of these products. Jett doesn't even give out horsepower numbers because in their words "it's hard to beat the first liar".
The most practical way to measure a glow engine's power is to measure the full throttle rpm and use the prop power formulas to estimate the power needed to turn the prop at that rpm.

01-18-2007, 06:02 PM
Thanks guys, I've got a much clearer picture now. :)


01-18-2007, 06:21 PM
HL says a .40 size motor is equivilant to 300-400w of power. That .65 might be in the 700-800 range, but as pointed out that is still not a apples to apples comparison.

You are generally better to use weight of model, wing area and expected performance to get you where you need to be with power systems...


01-19-2007, 02:00 AM
I built this 66 inch wingspan Stephen's Akro from a set of plans that I bought from some magazine. Designed for .60 two stroke/.90 four stroke engines. Weight is 7.166 pounds ready to fly. I'm using a e-flite power 60 outrunner, 4500 mAh 6-s lipo combo for power. With an APC 14x10E prop, it draws about 950 to 1000 watts at full power. This plane will do long if not unlimited uplines. I also have a 15x10E prop in reserve in case I feel that unlimited verticle is important.:D

01-19-2007, 07:27 AM
Hello everyone,

Just wondering if someone knows what a .65 glow engine puts out in watts? Thanks in advance.

You might have an opportunity to try these. Hope they help:
http://www.csd.net/~cgadd/eflight/calcs_gloconvert.htm (http://www.csd.net/%7Ecgadd/eflight/calcs_gloconvert.htm)
http://www.csd.net/~cgadd/eflight/calcs_motortest.htm (http://www.csd.net/%7Ecgadd/eflight/calcs_motortest.htm)

01-19-2007, 08:58 AM
Thanks everyone. I bought a Cessna Skylane balsa kit about 14 years ago and its still in the box lol. It was supposed to run a .65 so I was just wondering what size motor would be similar thats all. I'm not sure what the final weight of it will be. If it ever gets out of the box :)


01-24-2007, 07:23 PM
Haven't seen a 61 or a 91 for that matter that is even close to the Eflite power 60 on 6S and 16X10 prop...
8lbs...totally no compromise flying. vertical till it's out of sight .

01-25-2007, 03:38 AM
Haven't seen a 61 or a 91 for that matter that is even close to the Eflite power 60 on 6S and 16X10 prop...
8lbs...totally no compromise flying. vertical till it's out of sight .

Got any power/amp draw info with that prop? The weather finally let me fly my Eflite power 60 powered Akro last Sunday and I forgot to take my APC 15x10E along to try.:( So I soldered on with the 14x10E, even that powers the plane like I would expect a .60 2C glow engine to power it. The motor and battery don't even get very warm after a (I guess about 10 minute long) flight. My charger typically reads about 2000-2200 mAh after end of charge when recharging the batterys.

01-25-2007, 06:29 PM
1350 watts......just over 10 lbs thrust. 8 min flight takes out 1300mah from my FP lithiums.

Big Oakden
02-09-2007, 08:48 PM
Here's how I figure it:
100 watts per pound for a trainer
150-300 watts per pound for aerobatic if you want to make it really go, and hover well.
Just make sure that your ESC and Batteries are not the limiting factor of your power set up.

ie dont use a minimalist attitude when powering your plane. Spend the added dollars to equip your plane with the power needed to fly it and then some. Throttle management is the key: IF you need to take off at full throttle, and fly at 3/4 throttle, you are under powered. This doesn't leave you with any room to power up, and will use up your batteries sooner.

If you are planning on drawing 50-60 amps, don't use a 50-60 amp ESC. Pay the extra 20-30 $$ and upgrade to an 80 or 90 amp ESC, this will prolong the life of your ESC, and keep it cooler. Same with your motor. Figure the motor that will just fly your plane (watts/amps) then, look at the next two larger motors. If by adding 1 or 2 Lipo cells, you can increase your power greater that the added weight of the motor and the cells, it will be worth it to you in the long run. You are then left with propping the motor correctly.

I.e. the harder you push your equipment to fly a plane that it says it will fly, the shorter the lifespan of your equipment. If you "Up the Anty" to the next level and your air frame can handle the added 5-6 ounces, and your motor draws say 50 amps, your ESC handles 80-90 amps, your batteries can handle 75 amps; your ESC is just getting body temp, the motor runs cooler, and your batteries don't heat up after a 10 minute flight.

I have a Yak 54 that I am running this configuration with, and after several flights of 9-10 minutes each, each flight is drawing 2000 mah out of a 3700mah battery pack, and we were doing all sorts of aerobatics. The only maneuver we did not attempt was hovering. With my power set up, it should hover between 1/2 and 3/4 throttle after you slow it down to a crawl vertically. She will rocket ship vertically if you try to go vertical at half throttle and out of sight at full throttle.

Just my opinion,


02-09-2007, 11:25 PM
100 watts to the lb for a trainer is waaaay overpowered. 50 to 60 is more than ample for spirited flying. some I have flown at 40 , and they flew well...no they weren't particularly powerful, but they are trainers after all, and meant to learn to fly with...not do aerobatics...
For serious aerobatics, I use from 120 watts/lb ...more power isn't always better..
I have two identical 72" aerobatic models..one has 180 watts to the pound, and the other has 275 watts/lb...the one with more power doesn't perform any better..I was going to use it as my contest model, and the lower powered one as the practise model..after having flown both, I prefer the lower powered one in competition..