Yet Another C.G Question

[Heather]

Hi,

I have just completed an AT-6 Harvard conversion and am having trouble with the C.G. The plans said 2 1/4 inches from the leading edge at the fuse. I was skeptical of this as it seemed to far forward but went with it any way. It was way to far forward as it required almost full up elevator to stay in the air!

I have attached a picture with the dimensions of one wing panel. I would appreciate any help on working this one out.

It's a pain because I'd made such a neat job of installing the battery and now I'll have to change it all....

Heather

[davidfee]

Hi there,
It looks like plans were incorrect. Based on your drawing, I calculate that the CG should be about 3.5" back from the LE at the fuselage. If it was balancing at 2.25", no wonder it was taking full up-elevator to keep it level! ;) See attached pic:

[Sparky Paul]

I get a slightly different value, using the Palo c.g. computations...
Subtracting the artifical extension of the leading edge, there's a .1 difference in the locations.. not enough to be bothered about.
I've done this with the T-6 before, and found a 2.5% difference in c.g. with or without allowing for the sweep at the root, vs including the straight portion in the computations.
No biggie.

[Heather]

Thanks for that guys. I guess I'll start at 3.5" from the leading edge. I just hope I can still use the battery hatch I made.

Heather