1.1M Cat setup help

[Brushless55]

I wonder what would be a killer setup in my MM that has nutso speed and good run times on 4s or 6s?

[EPower]

Yep a Mean Machine Cat..
That Align motor on 5s in my MM would be killer!

Sorry M8 My mistake must be old age

[EPower]

Yep a Mean Machine Cat..
That Align motor on 5s in my MM would be killer!

Yeah can't wait to try one

[EPower]

I wonder what would be a killer setup in my MM that has nutso speed and good run times on 4s or 6s?

I guess you have to compromise somewhere you can't get the best of both words
I always go for SPEED

[Brushless55]

I guess you have to compromise somewhere you can't get the best of both words
I always go for SPEED

Well I was thinking if I went with a 14XL to a 12XL on 6s that way it pulls fewer amps (longer run times) than a faster motor but would rip on 6s..

[norbique]

This is also a very nice motor

●Input voltage:DC11.1-22.2V 3-6cell Li-Po
●Max continuous current:70A/85A(60sec)
●Max output power:Approx. 1600W/2000W(60sec)
●KV value:1650KV
●Dimension:spindle 5x65x43.3mm
●Weight:Approx. 300g

i will run one of these when i kill my KB45

Adrian

Where did you find this motor Adrian? How much does it cost?

Another question, and to get back to the original purpose of this thread.
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 very 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 of you have advised me so far:
(Lipo batts - I calculated 3.6V / cell)

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

[EPower]

Where did you find this motor Adrian? How much does it cost?

Another question, and to get back to the original purpose of this thread.
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 very 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 of you have advised me so far:
(Lipo batts - I calculated 3.6V / cell)

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

KB45-10L 1800kv @ 6S = 34560 *This probably the setup i would go with should get you aroun 50 to 55Mph i would not want to run more then 6S with a KB45 8S setup would be fine with the 580S
but running times would be fairly short around 3 to 3 1/2 minutes with a 5000mAh batt
Lipos are 3.7v per cell
Those motors are made by Align helicopters they are a Hybrid outrunner

[norbique]

Why are you all saying you would not go up with the voltage?!

Why do you think electricity is transformed up to hundreds of thousands of volts in energy transfer? To lower the currents, (thus the loss) at a given power.

If you use a lower KV motor you can have the same RPM, same power, the only difference is higher volts, less amps, (less heat) correct me if I'm wrong.

P = U * I
P - power
U - volts
I - current

For example lets suppose we have 2KW of power.
1st case: 20V * 100A = 2000W - here you need as monster ESC
2nd case: 50V * 40A = 2000W - here you can live with a smaller (current wise) ESC which has higher voltage capable MOSFETs, aka: HV ESC.

I dont' get it?!

[Brushless55]

I know there is no substitute for horsepower but 580s in a SV27 that's a total overkill LOL
This is also a very nice motor

●Input voltage:DC11.1-22.2V 3-6cell Li-Po
●Max continuous current:70A/85A(60sec)
●Max output power:Approx. 1600W/2000W(60sec)
●KV value:1650KV
●Dimension:spindle 5x65x43.3mm
●Weight:Approx. 300g

i will run one of these when i kill my KB45

Adrian

I think this motor could work great.. low kv and run 5s or 6s

[EPower]

Why are you all saying you would not go up with the voltage?!

Why do you think electricity is transformed up to hundreds of thousands of volts in energy transfer? To lower the currents, (thus the loss) at a given power.

If you use a lower KV motor you can have the same RPM, same power, the only difference is higher volts, less amps, (less heat) correct me if I'm wrong.

P = U * I
P - power
U - volts
I - current

For example lets suppose we have 2KW of power.
1st case: 20V * 100A = 2000W - here you need as monster ESC
2nd case: 50V * 40A = 2000W - here you can live with a smaller (current wise) ESC which has higher voltage capable MOSFETs, aka: HV ESC.

I dont' get it?!

that is all true all i'm saying is that all the KB i have seen running at high voltage never lasted more then a couple of runs

[EPower]

Hi,

A friend of mine and I want to build a balsa cat about 1.1m long.

We want to power them by twin motor system and we were trying to figure out what motors, ESCs, batts we would need to make these boats run fast. Our goal is to reach speeds of around 100km/h.
I'd like to ask you, the experts to give us some suggestions, 'cause we have no experience with these kind of big boats, and limited experience even with smaller cats.

Please note he has limited budget.
All suggestions are welcome, thank you!
Norbert

This was your original post saying he has a limited budget 100 k is possible on a 6s setup

[norbique]

You're right EPower and sorry, it was a typo. I meant "we have limited budget" and not "he has limited budget".

What I try to say is you can save on battery costs by not buying 2x 6S packs (12 cells altogether) wire them in parallel and use a higher kv motor. But to buy 8-10 cells and wire them in series and go with the lower kv motors.

What do you think why did the KB's on higher voltages last only a couple of runs? Magnet wire insulation problem or why?
Or did they use higher voltage on higher kv motors, thus forcing them beyond their current and RPM limits?!

[Brod]

I think this motor could work great.. low kv and run 5s or 6s

Those Align motors are nothing special,i fly helis mainly,they are fitted as standard in the Trex 600,seen a few burn up on 6S lipo and not flown hard either.
Most of the Trex 600 guys change then for better quality motors.
Brod...

[norbique]

Those Align motors are nothing special,i fly helis mainly,they are fitted as standard in the Trex 600,seen a few burn up on 6S lipo and not flown hard either.
Most of the Trex 600 guys change then for better quality motors.
Brod...

What are those better quality motors? Could you name some of them?

[Brod]

NeuMotor 1515/2.5D/F on 6S,
I run a Tango 45-07 on 10S in my Trex600,comes down cold after 6 mins of hard flying.

Not cheap but both superb motors.

I like many,just cant put these expensive motors in boats,we only get 1 or 2 visits to the lake every week.
My helis get flown much more often,so warrant a big chunk of cash on the power systems.
I just ordered 2 Medusa motors for 2 of my FE boats,i will report when i get them fitted.
Brod..