speed calculation

[gio1966]

What kind of speed you should expect using a Leopard 5692/540KV with a 16S config(4X4S 5000mah 40C) esc 72V/200Amp
I've tried to use the calculator but I dont know what I'm doing.....yet.
I'm building an Insane Cat Gen I dimension 40x16.
Thanks

[carlcisneros]

what props?

[Fluid]

There are major potential problems with this setup. Is the ESC you have chosen reliable? Does it have a proven track record on 16S?

Next, 16S is a lot of voltage and is probably not particularly safe. I have seen boats running 14S, and just plugging in this much voltage sparks like crazy. 10S is bad enough, a 60% increase in voltage is massive. Why do you want to do this?

The Leopard motor is rated to '20S' but really, that is just a mathematical calculation. They actually rate their motors by watts and maximum rpm, then just calculate the "maximum" voltage to hit the max rpm, and divide to get the amps - but they screwed this up on their website. With all the other 5692 motors, multiply the max amps by max volts and you get close to 5500 watts. The motor you choose says it's rated at 5500 watts, but if you multiply the amps and volts you get 6500 watts, too much. On 74 volts the motor is actually rated to only 74 amps.

Limited by the 5500 watts specified for the Leopard motor you will go no faster than with a Castle 2028 motor and 10S....between 60 and 65 mph in oval racing trim, 5-10 mph faster for short run SAW runs. Speed will depend on the prop loading and the boat setup. Keeping the watts the same you will have longer run times IF you can keep the motor, ESC and pack temps in line.

If you really want to go outside the box with this build, and you understand the risks, then go for it. But if this is one of your first FE builds, I cannot recommend it.


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[gio1966]

Thanks for the info, the prop would be maybe 442 445 or if I can run 1/4 cable 6717, 6516

[graill]

72v? Braver than i sir. post any pics if you get this running.

Btw Fluids advice is primo.

[gio1966]

I will.....

[Fluid]

I am sorry to be blunt, but you clearly have no idea how FE boats work, nor should you try to build such a high-powered boat - yet. Your choice of props demonstrates this lack of understanding very clearly. A 42 mm prop would have no chance of moving a 40" cat more than 30 mph if that. A 67mm prop is too big for the motor/power you want to use. If you really believe that either prop will work, then stop thinking about building such a boat right now. You will end up with a boat which does not meet your expectations, will burn up components, will cost you a lot of $$$, or a combination of all three.

I strongly suggest that you start with an RTR cat like the Miss Geico or Motley Crew. Use one of these boats to learn about FE, then once you understand the basics you can begin to think about building a large, high-powered catamaran. Otherwise you are doomed to failure. Many newbies have tried what you propose - with predictable, sad results.



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[gio1966]

That clear ah! Yep I'm an undercover gas guy, busted! I really appreciate your input and will take under serious consideration. Again thank you.