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View Full Version : What kv and voltage 51"' mono



Brushless01
10-09-2011, 02:39 PM
Hi guys building a 51" mono and wondering which one of these and what voltage and could anyone make me a motor mont for this motor ? http://www.offshoreelectrics.com/proddetail.php?prod=leo-5698&cat=148
Thanks

Fluid
10-09-2011, 03:23 PM
You haven't told us what you expect out of the boat - speed, run time, use? What ESC will you be using? Does the hull have a lot of lift, or just a little? Of the motors listed get the one with the lowest Kv. Using 10S will reduce the amp draw for any given speed, protecting the cheap Leopard motor. I'd recommend a better motor for such a large hull, IMO the Leopard 5698s have excessive Kvs for your use. The Castle 2028 has performed well in large 10S boats.


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Brushless01
10-09-2011, 03:53 PM
sorry its a rio 51" and planning a swordfish 240 i looked at the castle but I dont feel like spending that much my speed goal is at least 45 mph just want something easy to drive.

Fluid
10-09-2011, 06:45 PM
With that speed goal you'd be better off with this motor:

http://www.innov8tivedesigns.com/product_info.php?cPath=21_25_68&products_id=368

It has a Kv much more appropriate for your speed goal, and it will be able to spin a prop large enough to push the Rio around decently. The Leopard just has too high a Kv for you. The Scorpion costs about the same as the Leopard does too. What batteries will you be using, 10S1P?


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Brushless01
10-10-2011, 01:57 AM
Thanks ! Do you think that i could get 50mph with that motor? and not sure on batteries or voltage yet will depend on what motor i end up getting.

Alfa Spirit
10-10-2011, 03:14 AM
For a large mono, go for 8S or 10S

Fluid
10-10-2011, 08:08 AM
You have it backwards. All the power in any boat is in the packs, not the motor. Decide how much battery you can afford, then match the motor to it. If you have 10S1P/3300mAh/25C packs then you will not want a high draw motor; with 10S2P/5000mAh/45C you can get about any motor you want.

You might be able to get 50 mph with the Scorpion - but you keep changing your speed target. The Scorpions don't like to run over ~120 amps or they start getting pretty inefficient. This means there is a practical speed limit - what it is depends on the boat. The Rio is large and will take quite a bit of power to drive it. Big boats are not cheap, trying to build one cheap usually results in a poor overall performance and reduced owner satisfaction. I'd save up a few more $$$ and get a quality motor if you want higher speeds and good reliability with this boat.


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Brushless01
10-11-2011, 02:57 AM
Thanks fluid i can get 10s2p batteries ( four 5s packs 2 in parallel 2 in series) I saw a thread by keithbradley with a large mono with a 5692 and it flew so im thinking that a 5698 will do or that scorpion so confused... sorry for changing the speed goal something around 50mph would be great.

6BOOST
10-11-2011, 06:19 AM
What I find interesting is you say you don't want to spend the money on a castle 2028, yet the 5698 is still $209? If you shop around you can find the 2028 new from various stores for $299, I know as I've purchased 2 of them recently. This motor IMO is twice the motor for only $90 extra, and this motor on 10s2p has pushed a 51" mono to over 60mph, and 70mph on 12s. For your 50mp goal you could keep the prop very modest, have low temps, low rpm and long life of all your components. Fightercat has a nice esc that is cheaper than the swordfish here:

http://fightercatracing.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=87&category_id=10&option=com_virtuemart&Itemid=1

If you decide to stick with the leopard, as mentioned, a low kv on 10s would probably give you the best amp draw vs heat vs speed.

6BOOST

Make-a-Wake
10-11-2011, 09:15 AM
If you're only wanting 45-50mph you can go with the Leopard 5698.................different kv's will dictate voltage obviously. The 1100kv on 8s will get you there easily.........a smallish prop can be used for your desired speed and amp draw will only be moderate. I'm a fan of 10s and lower kv for the big ones myself, but your speeds are very reasonable so 8s can get you by. However, if i went with the 5698 myself, i would go 835kv on 9s spinning something in the 55mm range..................any of the 5698 combos will give you 50+.

Doby
10-11-2011, 10:07 AM
Keep in mind that low 50's are approaching the limits of this hull and at those speeds, it WILL handle like a 51", SV-27.

Brushless01
10-12-2011, 02:43 AM
ok thanks guys would i be able to use the stock prop with any of the leopard motors ? And I already have 3 4s packs so 8s would be best.

Alfa Spirit
10-12-2011, 04:02 AM
What about a twin setup?

Brushless01
10-12-2011, 02:31 PM
Thought about a twin setup but too much work and the drives on it are good anyway.

Doby
10-12-2011, 03:21 PM
FYI, if you are using the stock flex and propshaft...don't....it will not hold up to the power that a large electric motor will put on it....i went through 3 until switching to an aftermarket assembly. Each one resulted in lst props/ dogs etc.

Brushless01
10-13-2011, 02:28 AM
ok thanks doby so either the leopard of scorpion hmmmm

Brushless01
10-14-2011, 02:19 AM
Going with the 835kv on 9s spinning around a 55mm prop thanks make-a-wake !

Punisher 67
10-14-2011, 03:57 AM
As mentioned already go for the 2028 over the scorpion if you are looking in the $299.00 range , 725kv - 775kv is ideal for a 10 cell setup . 835kv on 9 cells with a 55mm prop will get you in the 45 - 50mph bracket easy . I personaly like low kv high voltage setups - certainly a lot easier on electrical components .

Alfa Spirit
10-14-2011, 04:25 AM
The Aquacraft RIO 51 is a very nice Fountain hull :w00t:
10S is a good choice, I mean 2x5S or 4x5S foor more runtime. This is better to adjust the COG and how is the water
If you run 10S choose a Leopard 5698 835kV or 910kV sport version


Large and nice boat, FOUNTAIN Replica :thumbup1:

http://img62.imageshack.us/img62/6676/mhzfountain67.jpg

http://img810.imageshack.us/img810/5003/mhzfountain73.jpg

Make-a-Wake
10-14-2011, 10:11 AM
Going with the 835kv on 9s spinning around a 55mm prop thanks make-a-wake !

Thats gonna be a nice setup..................you're not maxxing anything out and you'll have some cool temps...................if you want you can go up to a 457 and get a little more speed and still be good, but a 455 will be 50ish and sound,

Punisher 67
10-14-2011, 10:54 AM
The Aquacraft RIO 51 is a very nice Fountain hull :w00t:
10S is a good choice, I mean 2x5S or 4x5S foor more runtime. This is better to adjust the COG and how is the water
If you run 10S choose a Leopard 5698 835kV or 910kV sport version,

Not with a 910kv on 10 cells - just my personal opinion Alain sorry - you'd be pushing some large amps with that combo

Brushless01
10-14-2011, 02:46 PM
ok thanks guys what mount would you lot recommend ?

Browning
10-14-2011, 03:35 PM
I used one of these in a large Cat hull that I did and it worked really well and the build quality was great..

http://southriverrcboats.com/shop/page/33?sessid=IA8I6X0ax98FpeebUQcpJizEfypBIQd30IYGpha2 MXww9SDYDyYZVrfzmBJpiN7u&shop_param=