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basic esc/ battery and other questions

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Old 08-03-2006, 01:48 PM
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RCDAD5
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Default basic esc/ battery and other questions

I have more experience with nitro plans (though still somewhat limited) and decided to give a small electric a shot as well. I bought a small foamy Cessna 182 with a speed 400 motor.. My main questions are..

1-The wiring on the plane shows I should connect the battery to the esc and then the receiver will be powered through the esc. Does the speed controle step down the voltage to protect the receiver? It seems an odd way to power up your receiver and servos given the rx (Futaba) only call for 4.8V?

2-The suggested batterey is a 9.6 to 12V 1100Mah. Wyh specify how many Mah? Wouldn't 2000 or 3000 Mah be better to get more flight time as you would with an electric car?

3-suggested esc is a 20amp, should I just go for a 25A so I can also use it for 500 speed motors later.

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Old 08-03-2006, 03:48 PM
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Default RE: basic esc/ battery and other questions

1. Yes, the ESC contains a Battery Eliminator Circuit (BEC) that steps down the battery voltage to the proper voltage for the receiver and servos. This is the standard practice for small to medium electric planes. The point is to save weight by avoiding the need to carry a second battery.

2. E-flight is always a compromise between performance and weight. A battery with more capacity will weigh more, perhaps so much more that the performance of the plane will actually decrease with the larger battery. The manufacturer has probably determined that the recommended battery is a good compromise between weight, thrust, speed, and flight time.

On the other hand, if you were to switch to lipo batteries, you could get greater capacity with no weight penalty. For the same capacity, lipos often weigh less than half as much as nickel-chemistry batteries. Lipos have pretty much revolutioned e-flight.

3. Using a larger ESC than you need is fine, assuming your airframe can tolerate the extra weight of the larger unit.

- Jeff
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Old 08-03-2006, 10:02 PM
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Default RE: basic esc/ battery and other questions

Thanks for the help jdetray, I thought it would be OK as stated in manuel but wasn't sure. The manuel on this plane looks like it was written in Chinese first and then poorly translated to English. I didn't pay much for it as there is a very good chance it will crash soon after completion[X(][X(]

The plane also says it can be painted. I've only used low heat covering for foam wings. If I choose to paint it do I need to use a specific model paint to keep the weight down? Painting the foam sound better the covering to me.

Thanks Again
Don
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Old 08-03-2006, 10:24 PM
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Default RE: basic esc/ battery and other questions

Hi Don-

When painting foam, using a paint that won't dissolve the foam is your first priority! Some canned spray paints will make a melted mess of foam planes.

Acrylic craft paints are safe for foam, come in a huge variety of colors, and can be airbrushed. Krylon H2O spray paints are foam safe. Certain types of Testors and Tamiya spray paints are said to be safe, but I have not tried them.

Whichever paint you choose, be sure to test it on a piece of scrap foam before spraying the plane. Use very light coats to keep the weight down and slowly build up the color.

- Jeff

Edit: Two other Krylon spray paints, ShortCuts and Fusion, are also being used. The solvents in spray paints are what will melt foam, but people are having success by misting it on from a couple of feet away. Your mileage may vary, so test before committing.

Edit 2: Another technique is to first apply a coat of water-based polyurethane to the foam. This will partially seal the foam and make it less subject to being attacked by the paint.

As you can see, finishing foam planes is a big topic, and I'm sure you can find whole threads devoted to it if you do some searching. I am definitely NOT the expert.
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