ORIGINAL: norbique



Hi! Thanks for your reply!</p>

I've been researching about this twin cat setup of mine I want to keep the amps low, so at a given power I must raise the volts. Less amps = less heat, less ESC muscle, but I need a HV ESC like the Turnigy 100A HV.
I'm thinking more and more about 6-8S setups. Especially the KB45-12L 1400kv @ 8S = 35840 RPM</p>

We're talking about X number of series Lipos and motor KV's but what I want to know is:
What should be the target free-run RPM for a 1.1m twin motor cat? What RPM range should I consider?
After some research, I am thinking that somewhere between 30-40K, am I right?! Cause if I knew this it would help me in choosing the right motor and the number of series connected A123's.

I made some calculations with th KB L's. The XL's are too much for this boat I think, also quite heavy, so I left them out for now. Correct me if I'm wrong.

Batteries are A123's NOT lipos. I calculated ~ 3.2V / cell

KB45-8L 2300kv @ 4S = 29440
KB45-8L 2300kv @ 5S = 36800 *
KB45-8L 2300kv @ 6S = 44160

KB45-10L 1800kv @ 4S = 22040
KB45-10L 1800kv @ 5S = 28800
KB45-10L 1800kv @ 6S = 34560 *
KB45-10L 1800kv @ 7S = 40320

KB45-12L 1400kv @ 5S = 22400
KB45-12L 1400kv @ 6S = 26880
KB45-12L 1400kv @ 7S = 31360
KB45-12L 1400kv @ 8S = 35840 *
KB45-12L 1400kv @ 9S = 40320

(I marked what I think are good setups with a "*")

And here's what some people have advised me so far:
(Batts are Lipos - I calculated ~ 3.6V / cell)

Feigao 540 8XL 2084KV @ 4s = 30009
B44 on ebay 2000KV @ 6S = 43200
KB45-08L 2300kv @ 4s = 33120</p>