R2 hobbies cat build

[ratchet]

Hi guys,

Well, I decided for my build that I am going to be using my 2 5000 mah in series (2x7.4v) in series for my godspeed 32.3" cat.

I will most likley stick to the 4mm drive system until failure, and the stock mounting system.

1) Can you guys recommend an esc / motor combo that will get the boat running faster than a stock mystic 29 ? My friend just got one & it handles great, but needs more on the top end & I don't want to be slower than him.

I was thinking a 180 amp esc, plus either a 4074 leopard @ 2000 or 2200 kv, or with the batteries I'm using, should I go with a 3674 setup. Will a 4074 fit under the canopy ?

Any other recommedations ?

What would be a good prop to start with ? I don't want to spend time polishing / balancing.

[iamandrew]

that will go fine, fairly sure a 4074 will fit. I dont know if theres actually much or any difference between the 2000 or 2200kv leopards.
I would try a X442 or a x642

[dana]

Grab a 3674 2200kv

[znus]

I have built the very same hull. It's a nice light hull but it's not really built for ~60 mph. At least not the transom. Be sure to reinforce it with some epoxy/glass mixture. Just pour it down there and let it dry overnight

Mine had a 4082 on 6s2p, 5000 mAh longpacks. Had to trim some edges to get the lipos down there

IMAG0061.jpg

And this is what happened on a high speed attempt :)

dellen1207.jpg

Which I repaired with another lump of epoxy, and GPS'ed it to 57 mph without any adjustments whatsoever.

dellen1212.jpg

Action shot!

dellen1219.jpg

[ratchet]

What difference would there be between a 3674 & 4074 ? I know the diameter, but perrformance wise ?

Can anyone point me to some 3S batteries that would fit in the hull ? I can't seem to find much that are think enough to get in there. Just in case :-) before I place my order.

Thx

[znus]

What difference would there be between a 3674 & 4074 ? I know the diameter, but perrformance wise ?

Can anyone point me to some 3S batteries that would fit in the hull ? I can't seem to find much that are think enough to get in there. Just in case :-) before I place my order.

Thx

The 4074 will provide some 500 watts more or something along those lines, it can handle a bigger propeller and make your boat go faster. All at the cost of more amps drawn. Can't help you with the batteries, sorry

A 3674 is more than enough for that hull. My build with 4082 and 6s2p was SAW only and standing still it almost sunk because of the big Lipos

[ratchet]

Thanks Znus..............Nice action shot pic.

Like I said, I just want to make sure I go faster than my friends mystic 29, by a bit, as I believe he will be upgrading soon :-)

[steamboatbob]

i have one of these

put in a leopard 4074 2200 KV
turnigy 180AMP esc and run it on 2 * 7.4V zippy 5000mah batteries 14.8V
and x445 prop

it runs ok and had it measured at 80KPH

http://www.youtube.com/watch?v=M-shnY_bWbU&feature=relmfu

[ratchet]

I looked at your pics & vids. Thanks - I wonder if the motor & esc would fit with the stock mounts ?

[steamboatbob]

i opted for replacing the stock mounts with a motor mount that has cooling just to make sure the motor stays cold which it does, the only problem i have is the esc caps get very hot so i have been toying withthe idea of getting a cap bank or replacing the existing caps with new ones.

but all in all i have definately had my moneys worth out of this boat.

it is a good starting point

[siberianhusky]

Bob, what C are the batteries? With that setup the batteries could be the problem causing the caps to heat up, When I use the one set of turnigy batteries I have the caps get hot, even though they are a higher C rating than my high end packs, even my 30c gens ace perform much better in the voltage supply under load dept. I turn that prop in a couple spec boats, you should be putting less stress on that bigger esc and motor than I do with a 60 amp esc and motor!
Ripple current usually is what causes the caps to heat up, this can usually be solved with better batteries, when the batteries can supply the juice the caps do much less work.

[steamboatbob]

the batteries i have husky are Zippy 40C 5000mah 7.4

but they are almost 2 years old and my speedy is around the same age so in all honesty i think it might be time to replace them but they are only used once every 2 weeks and at the moment i dont see them comming out of the cupboard for a bit as i only just got out of hospital yesterday (had my evil twin removed) large cancer on my neck was taken out and 58 stiches later im in recovery.

[steamboatbob]

srry i should have stated that i run 2 packs in series to get 14.8 V

[Fluid]

Just because the packs say "40C" on the wrapper does not mean they really ARE 40C packs. Clearly, some pack assemblers are less than candid when telling the consumer the facts about their packs. We saw the same thing with round cells a decade ago, inaccurate labeling to get the consumer to buy sub-standard packs. I'm not saying that those packs are not 40C, but it sure doesn't sound like it.

Hot caps are usually caused by a high current ripple as the caps are constantly charged and discharged. Better cells will help, as will short power wires. Most installations will allow you to remove 2"-4" from each battery/ESC wire, reducing ripple and cooling the caps. The shorter the better, but they have to be long enough to be practical.

The R2 is the same hull as the HOTR and the original, the H&R Agitator. Mine was sold by Skunkworks, with a 3150 Kv Neu motor I set a record of 83 mph spinning a Prather 230 prop with one 4S1P/5000mAh 65C TP pack. This was a SAW-only high-end racing setup.


DSC00026.jpg

.

[ratchet]

Thanks guys.

I'll let you uknow if it fits with the stock mount......I may need to swap it out. I have this one on it's way. You can see the vid of it in a boat, and it looks to be the same as a leopard 4074. 2200 kv, or real close. If I have to change, I'll get a mount & upgraded drive cable from OSE.

Next week, I'll pick up a fightercat 160a esc, or a 180 hobbywing / turnigy, if anyone has them in stock.

http://www.hobbypartz.com/96m802-4074-2150kv.html