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-   -   New project need advice on CG (http://www.Wattflyer.com/forums/showthread.php?t=73771)

RTA 05-20-2014 08:00 PM

New project need advice on CG
 
New project no manual. I have a flat foamy in a triangle shape with a slight bull nose. :D 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.:confused:
Ron

mclarkson 05-20-2014 08:34 PM

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?

NJSwede 05-20-2014 08:38 PM

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:

https://dl.dropboxusercontent.com/u/3288510/CG.JPG

fhhuber 05-20-2014 08:41 PM

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.

NJSwede 05-20-2014 08:42 PM

Deep link to calculations:
http://fwcg.3dzone.dk/?wing_span=30&...ow_mac_lines=1

RTA 05-21-2014 03:54 PM

Thanks everyone. Your help is appreciated. I will go out and hopefully have a successful flight when I have time and weather is favorable.

RTA 06-24-2014 02:08 AM

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

suresharp 06-24-2014 03:34 AM

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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