leftyb

In getting back into RC planes I want to get an electric system that can be used in different, but similar, planes. For example, one hobby store wish book shows four different planes, all using a 370 geared motor with a 10x?" prop, 6-8 cell 5/4aaa nicad packs. All the planes have similar wingspans and wingloading. One plane requires a 5amp ESC, two require a 15amp ESC and one requires a 30amp ESC. Unfortunately, the hobby store does not have a "contact us" on their web site. If all things are similar what causes the different requirements in the ESCs? Is it just the desire to sell more ESCs? Would the 30 amp system function just as well in the plane with a recommended 5amp ESC? I believe I can understand what would happen if a 5amp ESC is used in a system drawing 30amps but I do not understand what would happen the other way around. (30amp ESC for a system drawing 5amps) Any suggested web sites that might explain this information or should I forget RC planes and take up floral arrangments?

Matt Kirsch

My Feedback: (21)

If the planes all have the same motor, gearbox ratio, propeller size, and cell count specifications, they should all draw the same Amps. A typical 370 application should draw around 8 Amps if you want the motor to last for any length of time. One of those planes has an undersize ESC, and the rest are a bit oversized.

What you need to understand is that the Amp rating of an ESC has no bearing on how many Amps will be drawn. That's something decided by the battery and motor. The ESC is simply along for the ride. You need to choose an ESC that will handle AT LEAST as much current as will be drawn by the system. As you presume, underrated is bad news, but overrated is perfectly fine. The only penalty for running too large an ESC is weight.

leftyb

Thanks for your response Matt. Every bit of information helps but I have a long way to go.
If I can keep from purchasing multiple motors, ESCs and battery packs because of small variances, I might be able to stay in this hobby.
Thanks again,

Matt Kirsch

My Feedback: (21)

If the variances are small, you won't have to. Just adjust the propeller and perhaps the gearing to suit the plane, or go with the most powerful combination and throttle back on the less-performance-oriented planes.

leftyb

Thanks for the tips Matt. You make very good points that I will keep in mind.