General Motor size

[Rackman]

hello everyone.. say wanting to fly this old plane but came to find that the motor for it was just not going to cut it. made it's way along the tarmac ok but just wouldn't leave the ground for a maiden flight .. so here I am wanting to change out the Motor & questening my choice of motors .. & probably the prop curnently it has a 8x6 propeller .. as for the plane it wieghs 39 oz. and looking on Ebay I found a Motor size is A1212 10t 1400KV Outrunner F450 MWC for RC Airplane. I was hope that someone could offer me advice on whether or not this would be strong enough to take this little guy up in to the skys .. battery is a 850 mAh 30C that im curently using for what is all is CG seems to be great..well I guess I'll leave at this to see what you all might have to offer thanks a head of time .. Rackman

 

[Rackman]

I guess I should have mentioned that it is a small Cessna 182 & it had a brushed motor in it.. amd Im wanting to go with a brushless motor with a 30 amp esc..

 

[Rackman]

guees I.ll just Bite the Bullet & go for the gusto made the choice to go with a 2312/960KV should be here in just a few days. hope it work & is strong enough
if not I'll try something eles ..well I hope All are doing well

 

[RandyDSok]

Electric motors model numbers are not how to judge what they are capable of but they may get you in the ball park.... you need the amount of watts they can provide. With the watts ( power ) and the kv you can guess closer to how close it is to providing what you need for the model. The remaining data you need is the recommended voltage they tested with and if you are lucky you would also know what props they recommend for the motor. Most hobby shops seldom give all that info making tough to pick a motor from it's specs.

My primary source for estimating what size motor to look at and one that gave those values I mentioned... has gone out of business. I'll see if I can find another possible source after work.

 

[RandyDSok]

P.S.

Most motor numbers are one of two types .. both physical size related. The most common is the diameter of the can by the length. The second most common is about the same but instead of the can size they measure the stator.

Batteries you need the cell count which is related to the voltage. You listed the capacity and how much they rated how much power it could put out vs the voltage you didn't list. Different battery chemistry will also affect what each cell voltage provides.

 

[RandyDSok]

Rackman,

Ok... Where I'd start if I were lucky... Look at the original brushed motor and see if you can find the specs for it. Specifically you want to know the kv and wattage for the size prop it was using. Then try and match those numbers in a brushless as closely as you can. A lot of the asian market products lack that info, so don't hold your breath looking for it, just hope to get lucky.

Also take into consideration the weight of the original batteries and motor so you can keep from affecting the CG of the plane. The batteries can be shifted back ( given the room to do so ) to help keep the CG in place but remember that it is recommended to not lengthen the wires going to the motor for technical reasons I don't fully understand but all manufacturers seem to mention.

Another method I use often to get started with is looking at existing models of the same type, size and weight and see what motors they are recommending.

Since it's a Cessna 182 we know it'll be in the trainer class of airplanes. The info I was able to find was for sport and 3D planes that take more power than a trainer would. For that weight, most were in the 400w-500w range using around a 3s lipo and and 8 to 9x6 prop. Several were also spec'd up to 5s but those would obviously be overkill for a trainer and they also used much larger props as well. These motors were all in the 28xx sizes and around 1000 kv.

I'd probably start looking in the 250w range at the very least and likely would like to get something around 300w. I probably wouldn't exceed the 400w range since the motor would also come with additional weight.

 

[Rackman]

Thank RrandDSok all your information was very helpful ..sadly there was no info that I could find on the motor but with the combination of the motor I went with & he battery it seems to be a good match seems to be very strong at 3/4 of stick imput I went with a 8x6 pitch prop .. once the weather changes here were off to give it a shot to see how the maiden will go ... Thanks again..