Motor mounts

[CDNshy_guy]

Can anyone tell me why they put those black gears on the electric motors? Why can't we just put the prop on the motor directly? does it increase the spead?:confused:

[rcski]

I left this question since this morning cause I'm sure some one could do a better job. Oh well. It's called a geared motor. The reason I believe is, you can turn a larger prop with less effort on the motor. It all depends on Size, wieght, type. If you have a lighter plane and are looking for speed you would run without the reduction. I believe your motor would use more amps and the run time would be lessened. Jump in anytime anyone.

[CDNshy_guy]

Thanks
That sounds logical.

[genebond]

The speed of the prop and the speed of the plane are directly proportional for maximum efficiency. Just like different gears in your car. Yea, you can go 25mph in 4th gear, but it's more efficient in 2nd. You can also take off in 2nd gear, but you'd have to slip the clutch or torque converter (a centifugal clutch - of sorts) considerably, burning a lot of energy off in heat.

Same basic theory, if not as scientific as some would like...

[Jarvis]

The electric motors used in model aviation are adapted from other uses.. The sp280, 400, 500, 600
are mostly all made by one company to specs desires by the importer. They are high reving low torque motors for the most part. When we use them for model aviation we must gear then down to allow the motor to turn at its desired speed range while keeping the amps within the accepted range the motor was designed for.

All e-motors are designed for a specific maximun voltage (ae; power, # cells) and amps (force needed to turn the shaft before smoke comes out).
A whatt meter is useful to choose the correct size
prop to keep the amps within the specs with the chosen # of cells. The # of cells for a motor are listed in its specs, as well as prop size choices.

For slick fast models direct drive with a small prop if used, while larger models needing a larger prop must be geared down. The larger the prop needed the higher the gear ratio needed so that the motor can do its job keeping the load(amps) within its range. When using gearing the # of cells can be slightly increased (increasing power)
while the amps are reasonable for the motor.

If you want silent flight direct drive is the way to go since gears do sound-off. BUT you must be careful with most motors to keep the amps in check.. The multiplex 450, magnetic mayham and endoplasm(?)(rc-truck motors) are inexpensive
high torque motors that can swing a respectfully sized prop direct. Jeti phasor brushless (relatively inexpensive for its type) and the Mega
brushless are designed for direct drive applications and do a very good job of it..but they need brushless controlers and are much more expensive than the 20 dollar ferrite's mentioned.. about 100 to 140 dollars plus 80 to 110 dollars for the controlers.

I hope this helps.

Jarvis

[CDNshy_guy]

Ok Thanks Jarvis

[BrokenChild]

Sounds right. A one horse motor (just used as an example here) would put out 3 times as much power with a 1:3 gear ratio, but in turn you lose 2/3 of your RPM's. I wont say that a one horse motor would put out exactly 3 horses... look at it this way, just image in in your mind.

A 5 horse power lawn mower engine would run at say, 5,000 rpm's. if you put a big gear box on this 5 horse motor with a gear ratio of 1:5 then you would have 25 horses of power, but then again, you wouldnt get more than 1,000 RPM's then...

I know this isnt exactly true, just a mental example of the truth.

I keep struggeling on how to get it in my own words here...

Ok, a motor turning a 10" prop with a direct drive, running at 10,000 RPM's would be for a faster plane than another plane the same size and weight with a geared down motor... It would run like a plane with a 4 stroke engine then, with a larger prop, turning slower RPM's.... The trade off would be a motor that would haul a larger prop... uhh... more power because you have a bigger prop, and more of a constant pull, but less RPM's so you have a slower plane than the one with the direct drive...

Hope my nonsence made some sence...

broken