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Old 10-18-2007 | 10:14 PM
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Moppie
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From: Boiling Spgs, PA
Default Eagle Tree System - Fast Electric Help!

Suggestion- Fast Electric

History: When I started with my project last year I made a number of mistakes. But in the end I did reach my goal of over 55mph with my Titan 33. In getting there I burned up a new set of NiMh batteries and also lost a set of LiPo’s. – not cheap…

Today’s goal is to run in the high 40’s and be reliable. And so I bought an Eagle Tree System to monitor battery and motor temp., amp and voltage and motor rpm.

As part of this “post” I thought I would share some data… and get some advice.

At the end of an 8 min. run the LiPo batteries are at 130 F and the motor around 100 F.
I think 8 min. is pretty good when running at around 30 mph. So my though is to cut the run time to 5 min and up the speed to 47mph. If you look at the graph you can see the temperature in the LiPo building, it’s the yellow line.
Draw at 30 mph is around 57A (I have another run around 42mph at a draw of 72A).
Motor speed is around 20,000 rpm (10xl).

I still have lots of extra parts that will allow me to change the boat’s configuration. So here is a question for you experienced fast electric types. What would you use if you could select from the following:

Power is fixed at: 2S+3S Lipo (fixed in series) rated at 25C. Although I could do a 3S +3S in series.
10XL or 8LX Brushless…
T/m ratios from 2.07:1 (under drive) to 1:1 drive to 1:2.07 (over drive)
Props selections include Octura:
X447 3 blades
X448 2 blades
X440 3-blades
X445 2-blades
X646 3 blades
X640 2 blades
X438 2 blades
Y547 2 blades

Thanks for any advise.
Moppie

PS: Any suggestions on adjusting trim tabs. I’ve flipped the boat twice. In both cases it happened when I moved the batteries toward the stern. Should I move the batteries toward the stern but use the trim tabs to keep the boat on the water? The tabs have a slight amount of negative angle and the boat has a balance point of 30% of the distance from the stern.
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