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Batwing Question

Old 04-11-2010, 05:06 PM
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mwalsh6
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Default Batwing Question

I am attempt ing to build a Batman Batwing but am having difficulty determining the C of G. It will be a pusher using a .42 engine with the fuel tank mounted at the C of G. I have attached a photo of the plane and the wing measurements and would greatly appreciate any assistance. I tried using the online C of G calculater but the weird design made me second guess the results. I believe that this will be the critical factor in getting this bird to fly...

Thanks
Mike
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Old 04-11-2010, 05:28 PM
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Lnewqban
 
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Default RE: Batwing Question

1) Reproduce the shape on any piece of cardboard.
2) Hang the cardboard and a plumb from different points of the shape, marking the vertical line around the center of the shape.
3) The centroid of the total area will be located at the point where all the lines cross each other at.
4) Determine the MAC chord.
5) Balance at 25% of the MAC.
Old 04-13-2010, 04:56 PM
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mwalsh6
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Default RE: Batwing Question

I believe I understand but how do I determine the MAC cord?
Mike
Old 04-14-2010, 02:09 PM
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Lnewqban
 
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Default RE: Batwing Question

Mike,

Your wing is equivalent to a rectangular wing, which chord is considered the mean chord of all the little wings that conform your shape, or MAC.

I will try to do it for you later.
Old 04-15-2010, 10:20 PM
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Jim_Purcha
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Default RE: Batwing Question

Hi Mike, any plans available for that Batwing of yours? Funny I was thinking about this plane last month. I purchased a 1989 Batmobile and Batwing kit on the bay last month. My son and I are justing finishing the batwing model. Didn't realize how big the wing actually was compared to the Batman. Good luck with the test flying.

How does the Snowbird fly?

Jim
ORIGINAL: mwalsh6

I am attempt ing to build a Batman Batwing but am having difficulty determining the C of G. It will be a pusher using a .42 engine with the fuel tank mounted at the C of G. I have attached a photo of the plane and the wing measurements and would greatly appreciate any assistance. I tried using the online C of G calculater but the weird design made me second guess the results. I believe that this will be the critical factor in getting this bird to fly...

Thanks
Mike
Old 04-17-2010, 08:00 AM
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mwalsh6
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Default RE: Batwing Question

I do have plans but the fuse was made from a Fiberglass mold I carved out of wood.  Once I get this C of G figured out  I will take it for it's test flight and then I can upgrade the scale appearence. I will keep you informed of the progress.

Mike
Old 04-17-2010, 12:34 PM
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JohnBuckner
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Default RE: Batwing Question

The old practical approach to something like that is to simply make a small solid balsa chuck glider with just a profile fuse and no landing gear. Experiment with different CG's by ballasting with a few slugs of lead. Then use gentle straight ahead hand tosses .

John

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