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Airfield 1400mm Spitfire battery compartment and CG

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Old 11-10-2010, 11:26 PM
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ChuckW
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Default Airfield 1400mm Spitfire battery compartment and CG

Just wrapped up assembly of my Airfield Spitfire (1400mm version). I accidentally threw out my instruction sheet while cleaning so I was wondering what starting CG was recommended or people were using?

Also the only thing I question about the airplane design and construction is the battery compartment. A 4-cell, 2200mAh battery can flop around a lot in there which would affect the CG during flight. There is really no way to strap it down. How is everyone securing it? I thought about stuffing foam around it but I wonder if that would insulate the battery too much and possibly let it get too warm. My other thought was some sort of tray which the battery could be secured to then slid in and out. I wanted to see what others have done before I did anything though.

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Old 11-10-2010, 11:40 PM
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Default RE: Airfield 1400mm Spitfire battery compartment and CG

I guess I should have watched the video before posting. I figured out that the CG is 100mm. I guess I can just try some velcro on the battery. It isn't going to be tossed around like a 3D plane after all. I would still be interested in hearing how other people secured it though.
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Old 11-11-2010, 09:04 AM
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Default RE: Airfield 1400mm Spitfire battery compartment and CG

Just use the foam !! It won't make the battery get any hotter. If you build a "battery tray" you might mess up your CG.
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Old 11-11-2010, 07:13 PM
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Default RE: Airfield 1400mm Spitfire battery compartment and CG

I'm going to just try sticking it to the compartment floor with some velcro first. Even if it comes loose it will flop around but still be containe din the compartment. If I did build a tray it would be with very thin, light balsa. In addition to worryign about heat, I really don't want to sit there and cram foam down the compartment around the battery before every flight.

Everything on the plane is looking great. The retracts work nice to. I'll get the throws set tonight, verify the CG and hopefully fly Saturday unless the weather decides to turn bad.
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Old 11-21-2010, 08:48 PM
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Default RE: Airfield 1400mm Spitfire battery compartment and CG

Keep that CG forward. My P47 said 120mm and everyone is flying like 90-95mm.
Velcro is not enough, I have foam holding mine in from the top jamming it in. It was kinda Rube Goldburg but it works. The stock motor does not heat the battery up much on the 1400mm foamies so long as your not full throttle the whole time.
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Old 11-26-2010, 03:34 PM
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Default RE: Airfield 1400mm Spitfire battery compartment and CG

i would second on moving CG forward. i think Airfield's specified CGs are generally too far back. I had the 800mm Spit and it said to use 65mm for CG and the moment i took off, the tail dropped and the darn thing kept dropping one wing or the other and was outta control. i had to give more power and elevator down to try to keep it in the air and come around for a landing, but just couldn't hold it at one point because it was unpredictable and it went down. Then i moved CG to 45mm and it flew beautifully.

the new CG was at the top of the wing root curvature (not sure what the proper term is), so i'd imagine the big Spit would be the same location? so how are the flights, guys? i lost my 800mm Spit in a soy field and couldn't find it, and i think later someone found it for themselves. So i've been looking at its big brother for next season. the little one was absolutely awesome. i had enough motor on it to go unlimited vertical and its roll rate was just blazing. the frame was so sturdy and could take on all kinds of sharp pulls and yanking.
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Old 11-26-2010, 05:30 PM
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Default RE: Airfield 1400mm Spitfire battery compartment and CG

It seems to fly good with a 2200mAh 4-cell all the way forward in the battery compartment. The CG is somewhere close to 100mm, maybe a little less.
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