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lipomax · 02.03.2005, 01:10 PM

Energy = 1/2 mass x velocity^2
So yes, weight will use more energy to go faster, but velocity itself is the larger factor. Now, with RC cars, you have to add rotaional energy to this equation - I forget the rotational energy equation though.

With regards to small motors failing, Mike is right. A motor can only run as hard as it is able to dissipate heat. A huge motor that is insulated will fail, a small motor with good heat sinks and good cooling might be better.

Every motor has its inefficiencies. Let's say motor A is 80 percent efficient and motor B is 90 percent efficient. Let's say a motor can dissipate about 100 watts of heat. Motor B can handle 2x the power input than motor A!

That's why it's so important to get efficient motors. Brushed motors are less efficient and will run much hotter with less power input so that's one of the reasons why BL can handle more power.

Now, a typical small wind motor will be less efficient than a high wind motor (case in point, a Lehner Basic 5300 vs. a Basic 3100). Both motors are the same size, but the Basic 3100 is much more efficient. So, instead of using 7.2 volts with the 5300, I'd much rather go 11.1 or 14.8 volts with the 3100. Equal power, but much more efficient so less heat build up, more CONTINUOUS power.... blah blah blah.

So, I'm just saying get good cooling, good heat sinks, get a really efficient motor (but slow) and use high voltage and low amperage. You'll really have gobs of power, speed, and run time. Why do you think the Heli guys are going 10S lipo? They've already figured it out for us.

If you look at Lehner's brushless motor dyno charts, you'll see that for the basic motors, slower than the 3100, efficiency doesn't really improve so you don't need to go slower and higher voltage than 22.2 volts. However for monster trucks where amp loads can be very high, going even lower KV and higher voltage pans not because of gain in efficiency due to motor, but gain in efficiency due to lower amp draw through controller and wiring. Now I'm talking too much...

	(#22)
lipomax RC-Monster Carbon Fiber Offline Posts: 191 Join Date: Feb 2005	02.03.2005, 01:10 PM Energy = 1/2 mass x velocity^2 So yes, weight will use more energy to go faster, but velocity itself is the larger factor. Now, with RC cars, you have to add rotaional energy to this equation - I forget the rotational energy equation though. With regards to small motors failing, Mike is right. A motor can only run as hard as it is able to dissipate heat. A huge motor that is insulated will fail, a small motor with good heat sinks and good cooling might be better. Every motor has its inefficiencies. Let's say motor A is 80 percent efficient and motor B is 90 percent efficient. Let's say a motor can dissipate about 100 watts of heat. Motor B can handle 2x the power input than motor A! That's why it's so important to get efficient motors. Brushed motors are less efficient and will run much hotter with less power input so that's one of the reasons why BL can handle more power. Now, a typical small wind motor will be less efficient than a high wind motor (case in point, a Lehner Basic 5300 vs. a Basic 3100). Both motors are the same size, but the Basic 3100 is much more efficient. So, instead of using 7.2 volts with the 5300, I'd much rather go 11.1 or 14.8 volts with the 3100. Equal power, but much more efficient so less heat build up, more CONTINUOUS power.... blah blah blah. So, I'm just saying get good cooling, good heat sinks, get a really efficient motor (but slow) and use high voltage and low amperage. You'll really have gobs of power, speed, and run time. Why do you think the Heli guys are going 10S lipo? They've already figured it out for us. If you look at Lehner's brushless motor dyno charts, you'll see that for the basic motors, slower than the 3100, efficiency doesn't really improve so you don't need to go slower and higher voltage than 22.2 volts. However for monster trucks where amp loads can be very high, going even lower KV and higher voltage pans not because of gain in efficiency due to motor, but gain in efficiency due to lower amp draw through controller and wiring. Now I'm talking too much...