Need Advice With Aeromarine Mean Machine

[BobBonahoom]

I bought an AM 29.5" Mean Machine from someone here in Florida, but being a nitro guy, I have no idea how to set it up. First, the rudder is 4.25" below the rear sponson pad which seems really deep. Second, the rudder is 6' behind the transom, which seems really far back. Any suggestions?

 

[Chilli]

Try www.offshoreelectrics.com If you do a search, they have a few Mean Machine builds. A few years back there were allot of Mean Machine being built and most used a tapered Speedmaster .21 Rudder mounted close to the transom. Rudders are kept long to prevent the boat from spinning out in the turns. I wouldn't trim more than a half inch off the bottom with the 21 rudder. A great little boat and lots of fun with FE power.

 

[BobBonahoom]

Great, that is very helpful.

How about this...the motor in the boat is a 4092 at 1480 KV. I have a 180 amp ESC. Since the motor runs at 2600 watts, I assume using 4S batteries would generate 2600 watts/14.8 volts = 176 amps. Am I doing this right? That is right at the limit of the ESC.

Should I run it on 6S instead? If I run it on 6S, then 2600 watts is only 117 amps, which is lower and not pushing the limit of the 180 amp ESC. Also, RPM would be a lot higher at 1480 x 22.2 = 32,856 RPM.

I am not sure if any of what I just wrote is the correct way to think! Any suggestions for motor and battery with a 180 amp ESC?

 

[gil sonsino]

Hi Bob motor is ok and yes you can run it on 6S using your 180 esc (360 A burst) ...a prop with 47mm will be ok till you get used to this combo.Mike is correct about the rudder.Gill

 

[HTV Boats]

Bob,

You definitely have a 6S motor. Your math is correct but 2600watts too low for a 40X92. My 40X84s pull 3500-4000 watts on my data logger.

I have a MM29 I have been playing with for ovals on 4S. 2200-2400 KV works well there. I have a1415 1Y Castle and a T180. Mid 50's and setup to make laps. Rudder is 2 1/2" back off the transom and 2 1/4" below the sponsons. I use a skegged strut to help in turning. Deeper rudder increases handling and reduces speed. Kind of something to play with to meet your goals. Higher revs and smaller diameter high pitched props keep the amps down and seem to handle better.

Hope to see you at the Nitro Winternats.

Mic

 

[BobBonahoom]

Hi Mic, nice to hear from you!

Ok, so the fact that the motor is rated at 2600 watts does not mean it will operate there. If is operates at a max of 4000 watts on 6S, that would be 180 amps, which is right where the max limit of my ESC is rated.

The boat has an X445 prop on it. Is that a good starting point? Fits with what Gill said. (Thanks Gill).

What about batteries? I am told that I should run two 3S, 5,000 mahr, 100C batteries in series to equal 6S. Does that sound right? Where would you recommend I get batteries and what brand is best?

Bob

PS - I brought 4 nitro boats to Florida with me to race. I have never raced in a NAMBA format before. Should be fun.

 

[HTV Boats]

Bob,

Go with an M445 and maybe add an M545 to pickup 4-5mph with minimal setup changes. I like a little diameter reduction to 43-44mm. Two 3S 5000's in series will be 6S 5000ma. Don't get crazy over "C" ratings. Over 40c works fine. Battery labels are more Hype than accurate. You might look at two 6S 3000-4000 ma in parallel. Gives you 6000-8000ma and longer run time and the effect of a higher C rating. I have Hyperions, Dynogy's and my cheap Zippys that work just as well. When buying pairs get 3 and rotate them in. All it takes is one cell down and your pair becomes a single that you may not find a match for, I have 2-3 year old odd balls that I won't buy a replacement for. Go cheap and buy 3.

Mic

 

[BobBonahoom]

Mic, what are good places to buy batteries?

 

[BobBonahoom]

I just bought 3 Zippys from Hobby King. 6S, 4000 mahr, 40C.

 

[HTV Boats]

Hobby King seems to have the best selection and prices for lipo's. You can always find high dollar ones elsewhere. Dinogy, Giant Power

Search Value Hobby and All e RC. Two sources I have found good prices and service. Can't seem to paste a link here for whatever reason.

Mic

 

[Joern Markset]

I`ve built a couple of the MeenMachine and Sprintcat 29" which is basicly the same hull.
IMO smaller props and little more revs make the boat handle better.

You can see a short clip of one of them here: https://www.youtube.com/watch?v=dCNAphiIyN8

It is running on 6S with a 2000kv motor, if I`m not wrong the prop is X440/3

 

[BobBonahoom]

Joern,

That boat is going very fast! If I am doing the math right, that is around 44,400 RPM. That seems like a lot of RPM. People tell me to go for about 30,000 RPM for racing.

I have 2 motors, a Leopard 4092 2080 kv and a Leopard 4092 1480 kv. I was going to run the first one in P class on 4S and the second one in Q class on 6S. I was trying to get around 30,000 RPM in both cases. Based on what you are saying, I could run the 2080 kv motor on 5 or 6 S also. I would probably need a bigger ESC. What ESC are you using?

Beautiful pond there in Norway!

 

[Joern Markset]

Bob,

A 4092 means loads of power in this small boat, so don`t worry about the 2080kv, it will pull out straight
I`m running .150 flexcable with 3/16" stubshaft, and I could run X646/3 without breaking the cable.

In this particular boat I`m using the MGM 25035, but that is overkill, it was just a leftover that I could use. In the other MM`s and Sp.cat`s I`ve used ETTI 150A Opto.
All boats have been running 6S. (2 x 3S)

I`m using the Leopard 4074 / 2000 kv. Also tried TP 4040 / 1800 kv, that was, but less speed of course. And I tried the Leopard 4074 / 2200 kv, but it didn`t have enough power to pull out the X445 prop, so I went back to the 2000 kv motor. However the boat is much more easy to drive with a smaller prop, and better in the corners with 3 blades.

 

[HTV Boats]

One thing to remember is no load RPM and actual are quite different. Deduct 15-20% On my dataloger a 1600kv motor on 6S comes home 28000-29000RPM. (34000 something no load). Your 44400 will come in at 37000-39000.

On 4S this boat works well running a Castle 1515 1Y 2200kv, and a 1415 1Y 2400Kv using X642 and M445 props.

Mic