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Help needed! Motor and esc questions!

Pilot-294

Senior Member
#1
So last weekend I bought myself a new rc radio and a plane to boot (even tho the wife wanted to kill me haha) and I thought I did well. I got a brand new dx6i with the 2 extra micro receivers special and an older balsa sopwith pup model, long story short the guy built it, passed away, and never got to fly it. It was a couple years old so I bought a new battery, threw in the micro parkflyer rx included with my new tx and I flew it. But I fried the motor, the guy who built it was the late owner of the hobby shop so I thought his setup would be good so being new to setting up an electric plane I looked at what I had going on for guts;

This is what I found, he ran a 1320 mah battery and I got a 1300 park zone equivalent. He had what seemed to be an undersized 250-300 motor (I'm guessing 250) and the esc was the most amazing find, it's a 40amp e-flite pro brushless esc. The one I looked at was worth 75 bucks! Half what I paid for the plane.

And this is my question, what the heck size motor do I get to run the bird or will I need the esc too? I thought about a 400 size motor from heads up rc but I'm not sure what to get and I'm worried it won't fit on my current mount since I'm in an army base for USAF tech schooling and have no tools.

My other issue is I don't want any motor too big to kill the scale flying features of the plane and or damage the plane as it looks and flies very well and very scale and I like it that way. I also would like to keep the esc I have in it if possible as long as it definitely won't kill another motor.

Also the plane is made by green model rc and I can't find any info on it do I anyone has any offhand info without digging too hard I would apreciate it since the plans are pretty terrible , it was an ARF kit before I got it

Lastly a few specs on the actual plane, it's about a 35-40 inch wing and weighs about 16-20 ounces, not sure how accurate that is but I hope it's close enough
 
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Ak Flyer

Fly the wings off
Mentor
#2
I'd go with a park 300 or 370 to keep it close to what you had before. The 40 amp esc is way overkill. You could do with a 20 for those motors or possibly smaller. I think I'm running a 12 amp on a 300, I'd have to look again. I assume you are running a 3S battery. If not, the 300 will not spin fast enough. I'm currently having this issue on a 3D indoor plane. I haven't tried Heads up RC yet, but I have been getting stuff from altitude hobbies lately and they have near hobbyking prices but they're out of colorado and have $3.49 shipping to anywhere in the U.S. even to me in Alaska.

http://www.altitudehobbies.com/brushless-motor-peak-370-28-26-1100kv-suppo-2208-17
 

earthsciteach

Moderator
Moderator
#3
Hey, Jesse. Sorry ya lost the motor, but that sure is a pretty airplane! I'm back from a week at the beach and am heading to Lowes this morning. I'm picking up the foam to start your wing.

One more bit of info on your biplane would probably be helpful - what size prop is on the plane? I'm guessing it is a bit overpropped.
 

jetpackninja

More combat please...
Mentor
#4
The 400 slo fly motor would probably work fine.
Headsup RC is a quality outfit.
I've never had any issue with any of their products.

That 40 amp esc will work fine. Still probably overkill for a 400 size motor but not outrageously so.
No need to swap it unless you wish to use it in a different plane.
 

pgerts

Old age member
Mentor
#5
The reason you fried the motor is probably caused by a to large propeller for the motor/battery.
That is the only reason a motor should burn unless it got stuck somewhere.
The only way to know if the motor is to small is to know the span and weight of your Pup or find the manual.
A Pup was not very aerobatic so a small motor should be fine. 20 oz / 500 grams does not need a lot of power to fly.
Your old builder was not totally wrong. Any tiny part of glue in the wrong place could have caused the motor to fry.
 
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Ak Flyer

Fly the wings off
Mentor
#6
Agreed, too much prop adds amp draw trying to pull it and fries motors. One thing to remember when trying different props is to check the motor and esc temperature.
 

jetpackninja

More combat please...
Mentor
#7
Agreed, too much prop adds amp draw trying to pull it and fries motors. One thing to remember when trying different props is to check the motor and esc temperature.
Agreed- even better get awattmeter. Take the guesswork out of it. Seems expensive untll you start smoking motors and stuff
 

SkySlayer

ARC=Almost Ready to Crash
#9
Ok the reason it failed was because you threw the rx in the plane and these electronics mustn't be man handled so viciously.