what motor for 55" mono

[Shuttle]

Hey guys I am building a MMP Watersnake and would like to know what motor would you use. My goal is 80mph.
I'm little bit lost with a motor selection. Neu/Lehner is not an option, i'm thinking about Leopard 56110 and TP 5860 but maybe there are other options.
Another question is kv. From my expirence with Genesis cat no-load RPM should be about 40 000 while OSE suggest around 30 000.
On other hand i'm not sure expirence with a cat can be used for mono.
Waiting for your opinions and suggestions :)

[axel]

Have a look at the SSS from TFL, they are very reliable and used a lot over here, the 56104 its a 10D with 700kv.
Stay by around 30000rpm

[Shuttle]

I'm little bit unsure about SSS, 14000Watt looks phantastic. Power of Leopard & TP looks more realistic.
And thank you for RPM suggestion. Do you think i can hit 80mph with 30 000 RPM?

[photohoward1]

80? That's quite a task in a 55" Mono. You better have top rated parts and an exceptional ESC. Do some research on this forum to get some insight so you are educated and not frustrated. "nmnorth" does have a Neu 2230 on sale that on 12S or 14S may get you there.

http://forums.offshoreelectrics.com/...ed-Neu-2230-1y

[Shuttle]

I know about twin build of the same hull. 2*SSS motors, FLIER ESC, 62-63mm props. 74mph. 7-10mins of runtime on 12S1P 5200mah each motor.
I think using more powerful single motor can give me at least the same results. In above mentioned build motors doesn't pushed to the limits. 62-63mm prop isn't too big for 12 000 Watt motor :)

[Fluid]

So you already know what works in your boat? Two successful builders of large FE boats have made different recommendations - if you do not want to follow them, why bother us by asking?

The SSS is not a 14,000 watt motor, don't believe the printed specs. No cheap ESC will handle that power anyway. The advantage of twins is that you can use lower-priced motors/ESCs to get the speed you want.

That is a very big boat to run 80 mph but I'm sure it can be done - by someone. Several local club members have run 44" monos into the mid-70s with a single motor and 10S in oval setups, but those were not budget builds with the cheapest parts available. Too, you will need more than a 62mm prop to get that big old log moving that fast....


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[photohoward1]

what motor for 55" mono

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Rock on Jay

[Shuttle]

So you already know what works in your boat?

I know one successful build of Watersnake with two SSS motors and know one not successful build of RCMR's Donzi.
Donzi is also 55" mono. Powered by Lehner & Schulze and even didn't hit 62mph. As you can see, a top priced component doesn’t mean the one will succeed.
I think Lehner & Neu is for sport and/or top results. For hobby we have not so high priced components. Sure, Lehner/Neu is better than Leopard but what is the real difference?
30%? 40%? I don’t think so. 15-20% maximum.
ESC is another story.

Two successful builders of large FE boats have made different recommendations - if you do not want to follow them, why bother us by asking?

1 recommendation was about SSS and RPM. I will do as advised regarding RPM. SSS – I explained what’s bother me. Leopard, TP and SSS have nearly the same weight.
Declared power of Leopard & TP nearly the same but 12 000 watts of SSS just looks strange, at least for me.
2 recommendation wasn’t a recommendation at all, it’s some kind of general truth.

The SSS is not a 14,000 watt motor, don't believe the printed specs.

That’s pretty obvious and one of the reason I’m thinking about Leopard/TP. At least they specs looks more realistic.

No cheap ESC will handle that power anyway.

Sure, even at 90% efficiency at 14 000 watts will give us 1400 watts of heat. Pretty good kettle :)

The advantage of twins is that you can use lower-priced motors/ESCs to get the speed you want.

Ok, that’s idea is new for me. Thank you for sharing.
But I have a question; two Leopards/TP will cost about $400. Lehner’s price is about $600 (550eur).
Do you think putting Lehner on this hull will give the same result as two cheap motors?
I think like that (maybe I’m totally wrong):
Weight of twin setup is 13kg
Weight of single setup is 10kg
13/(2*cheap_motor_power) = 10/Lehner_power
Lehner_power = (20/13 = 1.5) *cheap_motor_power!
Do you think motor with nearly the same weight can deliver 1.5 power of average motor?
Mind you, Leopard/TP not so bad, they also use ball bearings & rare earth magnets.

Too, you will need more than a 62mm prop to get that big old log moving that fast....

I think for single setup I can start with 65-67mm prop and moving to 70mm.
But it looks like it’s not possible to hit 80mph with single setup.
In this case I need two motors. But which one to choose?
If any of my assumption is wrong - please correct me.

[Doby]

....and know one not successful build of RCMR's Donzi.
Donzi is also 55" mono. Powered by Lehner & Schulze and even didn't hit 62mph. As you can see, a top priced component doesn’t mean the one will succeed.
.

Did they people involved have a clue what they were doing, or did they just think that adding high dollar items would get them where they wanted to be (speed wise)???

[Fluid]

The OP knows more than you and I do Doby, let him figure it out......

[Shuttle]

I can say like that, it wasn't they first build. I also have no idea why this build failed.

[photohoward1]

I smell burnt ESC. Go for it. We could all be crazy. This thread went in a strange direction. Between Fluid, Doby and Myself I think we have about a Zillion years of experience. Oh well.


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[axel]

If someone says ´´ Neu/Lehner is not an option ´´ he has to take something like

SSS - TP - Leo

try and error

happy smelling

[Shuttle]

If someone says ´´ Neu/Lehner is not an option ´´

Ok, it can be an option, total price of additional motor, esc, battery packs and stinger is higher then difference between Lehner/Neu & SSS/Leopard/TP.
But, do you think Lehner/Neu can deliver 1.5 power of same weight/size SSS/Leopard/TP?
I don't think so. Maybe i have not enough expirence, maybe. But nobody answered my question "Do you think motor with nearly the same weight can deliver 1.5 power of average motor?".

I will take Fluid's recommendation and use 2 "cheap" motors.

he has to take something like

SSS - TP - Leo

Ok. And which one is better?

try and error

happy smelling

Don't worry about that :) Have 3 burned motors and no one esc yet.

[kfxguy]

I think your speed goal is quite unreasonable for that size hull with a single motor and the seemingly lack of experience. Maybe lower your goal to around 60 and you could probably get there. I always start slow and work my way up on new unknown builds.