Jekyll CG problem still exists

[David Gundling]

Message text written by INTERNET:discussion at nsrca.org
>Dave, our Fuse plans for a Jekyll 91 show the CG as 7 1/8 in. from the LE
.
This checks on the wing drawing at the panel root, and is at the front edge
of the wing tube. The panel root is 15 3/4 in.on the drawing, as a check to
make sure what wing you have.
Hope this helps
Jerry
RC Model Enterprises
----- Original Message -----
From: "David Gundling" <DGundling at compuserve.com>
To: "NSRCA Discussion" <discussion at nsrca.org>
Sent: Sunday, September 07, 2003 9:47 PM
Subject: Jekyll CG problem still exists


Used a Golberg CG machine to check the CG on my used Jekyll.
It comes out at 6.25 inches forward of the trailing edge. (7.75 inches aft
of the leading edge at the wing root or at 44% of the MAC)
Is this too far aft? If so how much further forward do I need to move it?
<

Jerry,

Thanks for the reply. I must have a very early version of the Jekyll 60. My
plane has a single piece wing (no wing tube) and the root chord is only 14
inches not the 15 3/4 inches your plans are showing. Assuming that the
moments scale, my CG should be  about 45% aft of the leading edge at the
root. This puts it at 6.33 inches aft of the leading edge on my 14 inch
chord wing, Does that sound about right? If my calculations are correct, to
move the CG from 7.75 inches aft of the leading edge as it is now to 6.33
inches aft of the leading edge where it probably should be, I need just
over 14 ounces of lead at the firewall.

Further  detail. Wing span about 67 inches. Root chord 14 inches. Tip chord
8.25 inches. About 750 sq in of wing area. Fuselage length rear of spinner
to trailing edge of the rudder is 66.5 inches. As stated earlier I think it
is the Jekyll 60. (I bought it used as a knock around ship. What I can't
figure out is what the builder did that would have the plane tail heavy
with a YS120 in front.)

Thanks for your help.

Dave
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