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Electric = .46AX?

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Old 02-10-2007, 04:58 AM
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wildchild45177
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Default Electric = .46AX?

I have a Tower trainer ARF that I want to convert to electric. I would loke to have about the power equal to a .46AX. I would also like to keep flight time around fifteen minutes. Suggestions (motor esc battery)?

Thanks Bob
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Old 02-10-2007, 01:25 PM
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salnsp
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Default RE: Electric = .46AX?

First, I have to ask. Do you own this aircraft or are you thinking about buying it. If you own it and have used it as a glow powered aircraft I would suggest you consider buying and new aircraft so you do not have to deal with a fual soaked refit. If you considering buying the Tower Trainer for electric conversion I would consider another aircaft also sold by Great Planes that is a dedicated electric aircraft. That is the Hobbico Electristar Select. Here s the address :http://www2.towerhobbies.com/cgi-bin...=LXNVC0**&P=ML

We also have it on our website:http://www.nesail.com/detail.php?productID=5357

This is a dedicated electric trainer comes almost ready to fly with brushless motor system and radio installed, and has the transmitter too. \

But, if you already have the Tower Trainer and you are willing to modify it for electric flight, I would probably go for one of the outrunners. Since the trainer will have a firewall mount you will need and rear or radial mount for the outrunner motor. You may have to build out the firewall so that the motor shaft clears the front of the cowling sides. you can also cut these back if required.

I do notice that Tower makes a suggestion for a motor system using a geared outrunner. Certainly this would work fine, but they suggest using two six cell 2000 mah NiCad packs wired in series for power. I would go to 4 cell Li-Poly for greater power and much lower weight and longer trun time. I would probably shoot for a 3-cell 3700 mah Li-Poly of 20C or so. Try to buy the korean batteries as the Chinese batteries are inconsistant in quality.

Here are two examples of motor systems to use, based on a 4 cell 3700 mah Li-poly of 20 C such as a PolyQuest, ThunderPower or Poly RC battery.

AXI A30-12XL
Kv 770
Max Amps 47
Thrust 91 oz
prop speed 64 mph
prop 12 x 8 APC


Kontronik Fun 480-3300 with 4.4-1 planetary Geardrive
Motor Kkv 3300 divided by 4.4 for gearbox = Kv 750
Max Amps 43
Thrust 88 oz
prop speed 52 mph
prop 12 x 6 APC

So you see for a trainer, I still wanted to get a bit more thrust than weight although we did not need as much as 3D aircraft. We stayed with a 4 cell Li-Poly so we would have good power and we kept the max amps under 50 amps. You could still use a good 45 amp speed control such as a Castle Creations Phoenix 45, keeping the cost more reasonable. The Hacker outrunner solution is much less money than the Kontronik Inrunner motor system. Of course this would be basically true if you substituted another inrunner or outrunner for the two I selected. The inrunner will be more efficient but considering the amount of capacity available in today's li-poly batteries this is not a really important consideration in this case.

We have to consider that the aircraft in mind has tricycle landing gear which limits the size of the prop, so for a 4 -cell Li-Poly system we want the Kv at the prop to be around 750-800 and a prop diameter that shouldn't exceed 12 inches or so.
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