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Foamies Talk about building, power setups and anything having to do with e-powered foamy planes!

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Old 05-20-2014, 08:00 PM   #1
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Default New project need advice on CG

New project no manual. I have a flat foamy in a triangle shape with a slight bull nose. The tail is 30 inches wide and the nose is 26 1/2 inches fron the tail. The motor is 12 inches from the tail end using a pusher prop and 3 cell battery. controls are evalons and it is all together and ready to fly. I don't know how to set the CG. I would like the maiden to not to a spectacle.
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Old 05-20-2014, 08:34 PM   #2
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As a rule of thumb, on a conventional airplane the CG should go between 25% and 36% of the way back from the leading edge of the wing.

That won't necessarily apply to deltas, flying wings, biplanes, and so forth.

I'm not sure from your description exactly what kind of plane we're talking about here. Can you post a photo?

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Old 05-20-2014, 08:38 PM   #3
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There's a nice calculator here:

http://fwcg.3dzone.dk/

Based on the numbers you quoted, it looks like your CG should be about 12 3/8" from the nose. Here are the numbers I entered:


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Old 05-20-2014, 08:41 PM   #4
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True deltas tend to work out to slightly less than 1/2 the distance from nose to tail. I'd start with CG at 11 inches from the nose.

That should be nose-heavy vs where you get best performance.

Set the elevons slightly up from level with the upper wing surface for launch.
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Old 05-20-2014, 08:42 PM   #5
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Deep link to calculations:
http://fwcg.3dzone.dk/?wing_span=30&...ow_mac_lines=1

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Old 05-21-2014, 03:54 PM   #6
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Thanks everyone. Your help is appreciated. I will go out and hopefully have a successful flight when I have time and weather is favorable.
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Old 06-24-2014, 02:08 AM   #7
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Default New project need advice on CG

I did the maiden a few days ago and it was a dream, didn't raise the heart beat one notch. I only had to move the battery a little ahead. Thanks everyone. It is a pleasure to have such info at my finger tips.
Ron
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Old 06-24-2014, 03:34 AM   #8
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This shuold be sim to STRIKER. Look up striker manual on line you will see that CG is about 7.5-8 inches from nose. Battery in this design is mostly at the front so cg gets pushed back.
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