Need help with speed calculation - RC-Monster Forums

Big House · **Need help with speed calculation -** 10.10.2009, 09:28 PM

I am trying to determine the running speed I should expect from my GTP. I am starting with 5s and I have the 2200kv Tork motor. According to mike's calculator, I will doing just under 40 on 5s. That does not sound right.

The specs are as follows:

5s lipo
2200 kv motor
G/R 3.14
tranny 1/1
spur - 15 for now

Just want to be in the 60 - 70 club on 5 - 6s.

Thanks.

simplechamp · 10.10.2009, 09:38 PM

Your spur should be much larger than 15T. 15T would be the size of the pinion maybe, but the spur should be 40-50T I think, don't know the stock spur for the GTP.

Export you results from the speed calc and post them here so we can see exactly what numbers you entered in.

Big House · 10.10.2009, 09:42 PM

Thanks. The Spur gear is 51 and the pinion is 15.

simplechamp · 10.10.2009, 10:01 PM

You'll need a much bigger pinion then, probably closer to 25-30T. This will make your rollout very high, so gearing like that will only be for speed runs. Won't have much acceleration and it will be hard on the motor, lots of current draw. Make sure your batteries are up to the challenge.

bdebde · 10.10.2009, 10:08 PM

I would use 6s for those speeds.

BrianG's calculator figures:

Differential Ratio: 3.3076923076923075
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 51
Pinion Tooth Count: 18
Total Voltage: 22.2
Motor KV: 2200
Tire Diameter (inches): 4
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor Coil Resistance: 0.006
Spur/Pinion Ratio: 2.83 : 1
Total Ratio: 9.37179 : 1
Tire Circumference (inches): 12.57 inches (319.19 mm)
Rollout: 1.34:1
Total Motor Speed: 48840 RPM
Vehicle Speed: 62.02 mph (99.62 km/h)
Effective KV Value: 2200
KT constant: 0.61 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...

Big House · 10.10.2009, 10:12 PM

Ok. Well tell me this--what would yield the best acceleration without taxing the motor or ESC? I will not be running less than 5s.

bdebde · 10.10.2009, 10:32 PM

Without taxing the motor or esc (too much), I would run a 16t pinion; 45mph on 5s and 55mph on 6s. I ran mine with castle 2200 on 6s and that gearing and temps were good and acceleration was incredible! Plenty fast too!