AM Mean Machine Nitro to FE conversion

[rcflyer55]

Thanks Reddy, I have it at 1/4 in up which is the most it will go in up ajustment. I also added about 1* of dihedral(up) by eye... I'll see how it goes tomorrow and post any video I get of it so I can get some help in fine tuning it.

[rcflyer55]

here is the video of its first run. I think I need to move the CG back a little. It's hard to tell where it is running with all the water splashing and looking out for ducks. Also there was a little girl fishing with a bobber to the left of me and I was trying to be respectful of her space.

I stopped running after 1 minute and checked the temps. Motor and ESC were warm not hot. At the end of the next test run the motor felt warm but the water jacket felt hot but only read around 100*F. The ESC only felt warm to the touch but measured 130* It;s a cheap temp gauge from harbor freight so I really don't think it is all that accurate.

watt meter readings were 16.81 Max Volts
102.9 Max Amps

The prop is a M445. I have no idea of what the speed was but I do believe it could go faster. It felt smooth in the turns with 60% expo. Much easier to drive then I expected. Just felt like it was on rails.

ANY advice is ALWAYS welcome.

http://www.youtube.com/watch?v=-VQJ_o6lAoY

[ReddyWatts]

Looking good! I would try a X642 prop, move cg back or/and increase strut angle. Should run somewhere around 40 mph.

[rcflyer55]

how about an M645?

[ReddyWatts]

I think it will be to much for the 120 amp controller. Not enough margin. FeCalc estimates 110 amps.

[rcflyer55]

thanks,
How do you check the actual watts the motor is drawing? I have an e-meter and it will only save the max Amps and volts. I can look at it with a plane on a stand and see static watts, volts, amps, and rpm. How do you do it with a boat?

[ReddyWatts]

You have to take a reading on the lake, so you need a data logger or watts up meter that records the max watts or a meter that records the dipped voltage and max amps to calculate the watts. Just run it for one lap.

FeCalc will estimate it for you.

[Avanti]

obrien had his MM dial in pretty good today on a feigao 7xl he won his class (we have a local club that does fun runs it was nothing to organized)

the MM is a very stable hull

[DISAR]

Very nice job, and nice thread, Congratulations!

In order to go faster, I would try the following:

a) Use 2 Lipos and not 4
b) Check the programming of your ESC and adjust it for 2 pole motors. Although I do not have the same, but when I set them to more advance timing, performance is improved
c) Try different props (40-42mm). You can try with the cheap Graupner series which are really good.

Thanks again for sharing this great info.

[DISAR]

Just to correct my self, I understand that you have 2 lipos 4s running in parallel.
If it is that so, for better speed you can use only one 4s lipo.

[rcflyer55]

Disar, I am using two 2cell to make a 4S 4500 pack. I saddle pack them to keep the weight even on both sides of the boat.

I'm waiting on my castle link, Without it, the hydra 120's lipo cutoff is 12 volts on 4S and that's too low for me.

I figured out the max watts of the run 16.81 Max Volts x
102.9 Max Amps = 1727.74 watts ???

I'm getting new lipos I didn't think the ones I had were cutting it. Without really running full throttle I barely got 5 minutes. So I am going to up the MA's and see what happens.

I will move the CG back and increase strut angle (thanks reddy) keeping the same prop at this point. I could change the prop but I don't have a way of checking the actual top speed anyway so I am going by the "feel" of it.

[DISAR]

The best way to monitor the performance of your boat is to have the following:

a) Eagle Tree logger with the optional temp. and brushless rpm sensors (it will measure volts,watts,mah,temps,amps etc.. except speed) Cost abt: 90$

b) Gps (forerunner 101,201 etc.. or other) to measure speed. Cost abt: 100$

[ReddyWatts]

rcflyer55, made any more runs or video's?

[rcflyer55]

I wasn't happy with the lipos so I bought new ones. I got the
TP 5000 EX V2's this time. Went on vacation and 2 were here when I got home. Waiting on the next 2. Was hoping to solder all 4 at once. Did I mention I hate to solder? :)

[rcflyer55]

New video added

I moved the cg back a bit, now it is between 8.75 - 9 inches from the transom, I increased the strut angle to 2*- 4* and I'm using the new LiPo's here is the video.

http://www.youtube.com/watch?v=419iP5PlT7Q

(watch in "high Quality" mode)