I have been flying electric planes for about 2 years or so. I am mechanically inclined and I tend to grasp things pretty quickly. However, when it comes to swapping out electric motors and ESC's and figuring watts, amps, and canooter valve settings, Im lost as lost can be.

That being said, I really dont want long complicated answers to the following questions. If you have links that explain the quantum physics of proper motor/esc/prop/plane combinations just post them and I will stuff my cranium later.

I have two planes in need of service.
1- Elfite Apprentice. This was my first plane and I still like flying it. Last spring I took a chance and flew with low transmitter batteries and now Im paying for it. Ive had one stock replacement motor because the bell cracked after a particularly hairy landing in a cross wind. The latest (and only the second real "crash") has repeated this injury. I went on HK and found a motor that I thought was a suitable replacement. I looked at the max amp draw and it said that it maxed at 32amps. The Apprentice has a 30-35a ESC so I thought I had a match. I bought the Turnigy G25. After receiving it I looked over the specs and in small print I see that it requires a 50a ESC. " Sigh." Can I use this motor in my Apprentice? If so, what modifications do I need to make to make it work?

2- I also own a Parkzone T-28. This poor thing has had a bad, bad, bad season. THe first thing that happened was that one of the battery leads wasn't soldered very well and mid flight, low, and fast, it died and crashed. It was a total dead stick. The entire front end snapped off, the wing mount broke, and the fuselage cracked here and there. I was able to to use epoxy and put the T-28 back together and make a plane of it again. She flew wonderfully. I was very proud, as it was my first major repair job. Then, another battery malfunctions. One of the balancing leads came loose from the battery and I dont know what it did but the ESC shut down and another dead stick. Luckily, it powered back up and I was able to drift it back down to land. Both batteries have been repaired, all structural damage repaired, and she went out for mid evening flight. The sun was low, the air was slightly cool with not the slightest breeze. I hand launched the T-28 and she cruised out to treetop level at WOT and I snapped her into a loop, like Ive done a million times, and it did a lazy sideways loop instead. It lost speed, and altitude, and must have gone into somewhat of a stall because control response was mushy. She rolled into a power line and hung off the vertical stab for a moment before dropping straight down. Now my T-28 motor is cracked and burned up. I have scoured the web and I cannot find a single post or forum that clearly explains what motor I can swap into the T-28. Im sure that to some it made sense, but it was greek to me. I do understand it depends drasticaly on how I want to fly the plane. I honestly wouldn't mind a little hotter flying but not red hot. What do I need to do to make this thing fly again?

I almost just want to rip the guts out of both planes, sell what I can, and buy something new.

These are certainly non-rigorous answers:

(1) The Apprentice: it's sized for a 15 motor, so your G25 should have plenty of power. The G25 is spec'd for a burst current of 44A, so they specify a 50A ESC. The actual amps you pull will depend on your style of flying, prop size, the amps the motor draws, the amps the battery delivers, but I'd guess that cruising around in mid-air the Apprentice probably draws 10-15 amps. So it should work, but the motor probably won't be working at its best efficiency. You may also have to check the CG, as I'd bet the G25 is heavier than the stock motor.

Where you might run into problems is full throttle operations, where the motor might pull more than 30 amps. That could burn out the 30A ESC, although it probably will tolerate short bursts of high amperage. If you fly it in a conservative manner, you'll probably be OK. If you're gonna put on a larger prop and fly 3D, you could run into problems.

(2) The T-28: Parkzone says it comes with a 480 size 860Kv motor. You could just go down to the LHS and get an eFlite 480 to replace that. If you're going to go the HK route on this, there's a Turnigy 480 size 1020Kv motor that will probably work. Or if you want to try to spice things up, get an eFlite Power 10. I did that in my mini-Showtime, which is spec'd for a 480, and love it.

In both cases, I doubt that these motors will be a direct replacement for the existing set up, so you'll have to figure out how to mount them on the supplied mounts, or come up with some kind of substitute system.

Hope this helps.

Thanks for the reply. Im having internet problems so that last post was a boo boo. What mods/hardware changes would be required for the Power 10? IF I go to the Turnigy, what ESC would I need? I think I will go with the G-25 in the Apprentice. I have it, might as well use it. I will have to buy an ESC Im sure. no biggee.

fixed previous post

Unfortunately, Horizon/E-flite/Parkzone doesn't publish specifications for their motors. But it looks to be roughly the same shape/size as a Power 10. So you might get lucky, and find the Power 10 will fit in the plastic mount included with your Trojan. If that's not the case, you'll have to figure out how to mate the Power 10's x-mount with the plastic mount. You've got a similar problem if you use the Turnigy motor: it looks like it's shorter than the E-flite motors, so you'll need to deal with standoffs and making sure you get the CG right on the plane. As for the ESC, the Turnigy is supposed to be a 22/28Amp motor, which the 30 amp ESC in the Trojan should handle. HK spec's it for a 40A ESC; mu guess is either the Turnigy or the Power 10 will function fine with the existing speed control.

On the Apprentice, I'd plug the G25 into the existing speed control and see if it works. The good news is that ESC's are coming down in price. I'd just take it easy on the throttle, and it'll probably work fine.