Outrunner info??

[zeropointbug]

Serum, last year i was going to do a true AWD setup with 4 Hacker outrunner motors. They are 550watt each so 2200 watt peak, this would be so kickass, this would prob be the best way to break the world speed record, no tranny, no diff's...

Eventually, i would like to make the motors right in the wheels, however you would have to make them light enough so not to make too much UN-SPRUNG mass, which would affect suspension abilities a lot.

[Serum]

I dont think it's the way to brake the world record. It takes 1 motor to do. 1 motor is lighter and will run more efficient.

[zeropointbug]

Yes, one 'bigger' motor is usually more efficient. Howver, because the outrunner would be running RIGHT at the wheels, there would be no transmission in between, you know you lose a lot of power through a transmission. THe outrunner's would end up running more efficiently.

[Serum]

No, that's plain rubbish.

the drivetrain doesn't take that much energy. wind resistance will be affecting it more.

Why do you think it is that the speedrecords are set with 1 motor?

[zeropointbug]

wind resistance IS the main thing it would be fighting against.... fundamentally.

if there was no wind resistance, any car could go 200mph, so long as the tires can could do it, not likely. Tire resistance also affects it too, not as much. But the heavier the car, the more resistance is put on the tire...

[jhautz]

Originally Posted by Serum

Why do you think it is that the speedrecords are set with 1 motor?

Besause that is the conventional setup currently used in almost all RC applications.

Don't rule out outside the box thinking just because ''most'' peple arent doing it that way now.

Creative thinking is the way technology gets advanced.


That said....
I do agree w/you that the energy lost in the drivetrain is negligable.
The bigiest problem I see w/ a 4 motor system is getting them all synced perfectly enough to keep a system stable at 100+ MPH. Getting 2 synced perfectly would be hard, 4 seems darn near impossible.

A 4 motor system seems to me like it could be one hell of a crawler setup though!

[BrianG]

Seperate motors on each wheel would take a different type of controller, or at least some type of signal adaptor. Since each wheel would have to spin at different rates when steering (which is normally taken care of with a diff) the controller would have to adjust the pulsewidth of the signal to the slower wheel based on the steering adjustment. So basically, if you are going straight, both motors get the same power. When turning left, the left wheel has to spin slower, so the controller would have to somehow factor the steering signal into the throttle signal to know that the left wheel is to spin slower. I guess basically how a tank controller operates.

So, the easiest way to do this would be to use a controller with two throttles and use that for steering and throttle control. Not very intuitive compared to a typical pistol-grip controller.

The other way to do this would be to feed the throttle and steering signals from the Rx into another "box". This box would then have two throttle outputs. The signal on these would be a processed signal based on the input throttle and steering.

I've done some thinking on this already. A typical output singal of a receiver is a series of square wave pulses at a frequency of 50-60Hz. The actual frequency really doesn't matter as long as it is consistent and not too far from these values. The positive part, or "on" portion, of the square wave pulses range from 1ms at min throttle/full left turn to 2ms at max throttle/max right turn. Steering center/neutral throttle is 1.5ms. So, a circuit would have to be designed to create two 50Hz squarewaves for each throttle signal whose pulsewidth is equal to the single input throttle pulse except when the steering is engaged. If turning left, the left throttle channel signal would be reduced in proportion to the steering pulsewidth. The same for the right side. I think this can be done relatively simply with some cheap linear analog circuits (op-amps, transistors, etc).

Maybe if I have time this weekend, I'll try to breadboard a couple of ideas. Might be a neat thing to market...

[Serum]

Well jhautz, i thought you knew me better than a person that rules out the outside of the box thinking..

I was making a statement towards this sentence;

'you know you lose a lot of power through a transmission. THe outrunner's would end up running more efficiently.'

Which is plain rubish..

[jhautz]

Originally Posted by Serum

Well jhautz, i thought you knew me better than a person that rules out the outside of the box thinking..

I was making a statement towards this sentence;

'you know you lose a lot of power through a transmission. THe outrunner's would end up running more efficiently.'

Which is plain rubish..

agreed

[Serum]

Glad we got this straight.. :005:

[coolhandcountry]

Originally Posted by Serum

Glad we got this straight.. :005:

ME TOO !!!! :027:

[neweuser]

Originally Posted by zeropointbug

if there was no wind resistance, any car could go 200mph, so long as the tires can could do it, not likely.

I also don't think ANY car could go 200 without wind. Motors themselves have limitations. RPM's and such. It would only be able to wind so much, not infinately. Maybe the design of any car with the right application could do it yes, but not just any car.

that may be a bit technical! LOL

[MetalMan]

Originally Posted by neweuser

I also don't think ANY car could go 200 without wind. Motors themselves have limitations. RPM's and such. It would only be able to wind so much, not infinately. Maybe the design of any car with the right application could do it yes, but not just any car.

that may be a bit technical! LOL

Actually, almost any car could go 200mph without wind resistance. The difference between different power systems would be how quickly they would get to 200mph.
Without wind, there would still be the friction between the tires and the ground. This is pretty much the only thing that would limit a vehicle from going 200mph when there is no wind resistance, but its effects could be reduced by using lower-friction tires.

Here's my reasoning:
Kinetic Energy (KE) = 1/2 x mass (m) x velocity^2 (v^2)
One way to express the unit for power is: Joules (energy) / time
The power of a system would be the determining factor for how fast the car would get to 200mph. Theoretically any car could go 200mph without friction.