rcguyfpr

iTrader: (52)

In a race, if the rule limit the motor kv at 3200kv (13.5 brushless). All racers have to adjust the end ball timing to 3200kv or below. Does that mean all motors will have the same or very similar rpm?

Does rpm or torque rotor matter in that case? (Gear ratio is fixed at 5.0)

Does ESC matter (blinky mode)?


Thanks!

Roelof

For sure torque will be the issue. Top speed is determed by FDR and max RPM limit so other qualities are needed. And because our tracks are like accelerating from corner to corner you do need torque. Maybe you can program a boost within the RPM range.

daleburr

Assuming they're testing unloaded, then you want the motor with the most torque possible. I.e. large-diameter rotor. You'll then be able to turn the endbell up to hit the target KV. This should give you more power than a small rotor with less endbell timing.

So basically it's a stupid rule that will encourage people to spend money testing different motors, rotors etc to get around it. Just allow boosted, it's a lot cheaper and fairer.

rcguyfpr

iTrader: (52)

In my case, there is a race. Non ramping, fixed gear ratio, fixed kv limit. My question is using the same car, with different brand of motor, under all these rules, will the top speed be the same?

V-point

Top speed will be the same, but acceleration will still vary by motor. Motors with better torque characteristics will accelerate out of the corners better, thus "getting a jump" on the motors with less torque. If you're going to all the trouble of enforcing a fixed gear ratio, why not just use a spec motor too? Even then, you will see differences over time according to who takes better care of their equipment.

Ivan Dickson

iTrader: (32)

What does KV stand for?

C@T

1000 rpm / V

howardcano

iTrader: (37)

The constant "Kv" is usually expressed on RPM/Volts. The "K" in this case does not mean "a factor of 1000"; it is simply the letter used to express a constant in the motor model equations.

Roelof

The only way to get more speed it try to get the tires larger....