Selecting a Motor

[JonB]

Oh I see. 100,000 rpm is insane. The motor probably has very few turns so it can't provide enough torque. Hearing it is an option but I think a ~2000-3000 kV motor should enable you to get up to top speed much quicker.

After seeing this vehicle run I cannot foresee much faster acceleration without loss of control due to traction issues. It's.... fast.

[Bazinga+]

Hm. Might be an issue of wheels. Back when I was doing wheeled vehicle I got it to accelerate in the first .5 meters and get a time of 1.9 sec, but it took a while for me to find the right wheels. Also you're allowed to reverse direction so you can go past the target distance and then reverse back to it.

[windu34]

Hm. Might be an issue of wheels. Back when I was doing wheeled vehicle I got it to accelerate in the first .5 meters and get a time of 1.9 sec, but it took a while for me to find the right wheels. Also you're allowed to reverse direction so you can go past the target distance and then reverse back to it.

Reversing direction to get to the end point is only reasonably feasible with a DC motor. Brushless A/C motors will not be able to maintain a steady position without some serious algorithms and even then, its just not going to be anywhere near as precise compared to a well practiced and documented wingnut system

[HandsFreeCookieDunk]

Yeah, I have looked into high-end brushless motors like Castle and while they are insane and the price is at least doable for me, I'm discouraged by the high voltage ratings because I don't want to have to find a converter to step it up. I guess there is no motor that's inherently perfect. Thanks for the help guys. Any suggestions on where I might find gearboxes or the parts I would need to do a homemade one? Seems that most of them come with a motor that I don't like.

[windu34]

Yeah, I have looked into high-end brushless motors like Castle and while they are insane and the price is at least doable for me, I'm discouraged by the high voltage ratings because I don't want to have to find a converter to step it up. I guess there is no motor that's inherently perfect. Thanks for the help guys. Any suggestions on where I might find gearboxes or the parts I would need to do a homemade one? Seems that most of them come with a motor that I don't like.

The best build designs/setups are often the toughest to create - this is what sets the teams who are in it for college applications from those who are in it for the challenge

[Bazinga+]

Well said.

[iwonder]

Brushless A/C motors will not be able to maintain a steady position without some serious algorithms

I'm a bit late I know, but most all brushless ESC's I've seen have a brake feature that stops the motor. One of the best features of BLDC motors (imho) is that they have a holding torque, and it's pretty straightforward to implement.

[rk9109]

Here's one thing I don't get. All of the brushless motors I've found tend to run at rather high voltages - how do you manage to run them with only a 9V power supply available?

We are currently using basic DC motors for 2 of the wheels running at 4.5 V each - I can't find any brushless motors that would take such a small voltage.

[InfiniCuber]

Here's one thing I don't get. All of the brushless motors I've found tend to run at rather high voltages - how do you manage to run them with only a 9V power supply available?

We are currently using basic DC motors for 2 of the wheels running at 4.5 V each - I can't find any brushless motors that would take such a small voltage.

Use a voltage step-up converter:)

[Bazinga+]

Here's one thing I don't get. All of the brushless motors I've found tend to run at rather high voltages - how do you manage to run them with only a 9V power supply available?

We are currently using basic DC motors for 2 of the wheels running at 4.5 V each - I can't find any brushless motors that would take such a small voltage.

Use a voltage step-up converter:)

I wouldn't. Which brushless motors are you talking about? All the ones I've seen are run by 2-3 cell lithium ion batteries or 5-8 Nickel cadmium batteries. A 6 cell buckle battery is 7.2 volts, so definitely in specs. I recommend a nice castle or turnigy brushless motor/esc combo.