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Classic Designs => Classic Planes => Topic started by: James Scohy on February 19, 2011, 11:24:47 AM

Title: Need Center of gravity for an old Thunderbird
Post by: James Scohy on February 19, 2011, 11:24:47 AM

I have an old thunderbird I built back in the mid to late 50's that I have stripped and am putting in flying shape.  It had some rough handling over the years and I had a lot of fabricating to do in the tail area.  In addition it will be electric when it is finished.  Can anyone tell me where the center of gravity is in inches from the leading edge of the wing root.  I would think that the Brodak version cg would get me close for first flights.
Thanks.

Title: Re: Need Center of gravity for an old Thunderbird
Post by: john e. holliday on February 19, 2011, 03:13:37 PM

A lot of uys argue this with me but in all of my modeling I have started at 25% of the chord and go from there.  Remember a nose heavy plane will live to fly again, but a tail heavy plane may go home in peices.   H^^

Title: Re: Need Center of gravity for an old Thunderbird
Post by: Don Hutchinson AMA5402 on February 19, 2011, 04:14:52 PM

On my '59 T-Bird drawings, a 20% CG is 2 & 5/8 inches behind the leading edge at the fuselage side. This would be a safe percentage for test flights, tweak to your liking as you get the bird dialed in.
Don

Title: Re: Need Center of gravity for an old Thunderbird
Post by: James Scohy on February 20, 2011, 08:19:38 AM

Thanks fellows.  The 20% mark looks about where I thought I remembered it, but at my age I don't trust my memory.  We'll star there any way.  Looks like nose heavy will be easy!