evan-RCU

I am in the process of converting my 16' span old timer to electric. I have the gas engine off, sealed up any extra openings, removed the gas tank and throttle servo. I have built a removable battery tray, and assembled and mounted the motor. I still have the ESC to mount up and tidy it all up.

One thing that I'm concerned about is the motor seems like it has quite a bit of drag on it. With no power applied it is a little stiff to turn. Not a lot... but enough to be noticable. I have run it up on a single 6 cell LiPo and with the 22x8 prop it pulls 20A and 480W and has good thrust considering it's on 6S. I will be running it on 12S 5000mA. And may end up with 12S 10000mA (four 5000mA 6S, 2series, 2 parallel)

Using this ESC and motor.

http://www.hobbycity.com/hobbycity/s...idProduct=4691

http://www.hobbycity.com/hobbycity/s...idProduct=5142



Anyone have experience with this motor? Is the stiffness normal or should I take it apart and check it out?

I've enclosed a couple pics.

DaveFlynn

Cool project, I want one!

If the wires from the motor are not connected to the ESC and not touching each other, then the only resistance to free spinning will be bearings and whatever cogging the motor has.

Some ESC's will act as a brake even when they are not powered.

If you want to get an idea of the torque that the motor can make, build a connector that shorts the 3 motor wires to each other and give it a spin.

evan-RCU

Good idea Dave. The drag has been present from the opening of the box, no ESC attached, and feels the same with the ESC attached or not. While it does feel a little like a brake is on it also feels like the motor was put together with some pressure on the bearings. Hard to secribe it. I'll try shorting out the three wires but I'm pretty sure that won't change anything.

BTW the motor does not have any apparent cogging.

DaveFlynn

No cogging is good. As long as it turns smoothly with no rough spots, it could be that the bearings are just tight. Good quality bearings will not spin freely they'll have a little pre-load.

pilotpete2

All I have to say is wow.
Magnificent looking giant scale model[8D]
Best of luck with the E conversion.
Pete

evan-RCU

Thanks, It has about 100 flights on it gas powered, been featured in a bunch of mags and DVDs even makeing it into a British RC magazine. Going E is getting so cheap I had to do the conversion. It was this or buy a couple of canoes and call them floats....

evan-RCU

Dave, I tried the shorting and guess what? That made it feel like a brake was applied. Unshort less drag, short more drag... I think it is normal so I kept building, all the little things like fire wall holes for wires and coating things with thinned epoxy. I still have so much to do though. Easy to have it ready for spring though.

OEMFlyer

Try running the motor for a short time and then after you shut it down and disconnect the battery, feel the motor shaft where it enters the motor on each end. If it is cool or the same temp as the rest of the motor the bearings are probably not too tight

grimmy55

A quick question ,,, How do I work out the thrust of a motor I see in a cataloge so that I know I,ve bought the right one ie my plane(Dehavalind Rapide 96inch wingspan) should come out at about 12 lb I think ,I have 2 motors 45-60,500kv turnigy will they be gutsy enough to give it lift on a 4cell lipo....if not what do you people recommend I should do as I,m at the stage of mounting them in the engine nacelles any help would be great

DaveFlynn

That 500 Kv motor on 6S with 9x6 props is equivalent to a .25 glow engine. It will fly, but you might want something bigger. What size prop fits the plane best?

jmohn

Dave,

I was thinking the same thing. Only 480 watts will not be enough to fly this plane. I am guessing that you will be running on 12S like you mentioned so that gives you maybe 1000 watts. How much does the plane weigh? Try and shoot for 70-90 watts per pound on a high wing trainer like that. I use a 12S setup on a couple planes and am getting 3000 watts using an Eflite Power 160 motor.

Jeff

DaveFlynn

It would be 480 watts x2 which is OK, but you'll be at full throttle a lot. If you can find a 4020 size that you can use 9S and get 600 watts or so each.

evan-RCU

I've been out of town working for the last 3 weeks and got home today and disappeared into my hobby room. I got the connectors on the batterys done and was able to test out the whole system on the plane though I used the old 22x8 prop that I used with the gas motor.

!!!!!!!!! wow, I am impressed. It is smooth and runs very nice. Easily 20lbs of pull. Of course it blew everything in my work room around.... The motor gets about 80 deg and the ESC is stone cold, batteries also do not get above ambient but they shouldn't, I'm pullin pretty low amps.

I can't wait to get the right prop on it.