Wow that title could be used as a tounge twister..

I am C.G. ing my Gee Bee Z, and thought I read somewhere that the CG was published in the instructions incorrectly. Mine says 70mm or 2 3/4". Is anybody else using this CG?


Dan

Hi Dan,

I have 42 flights on mine and IF I recall correctly, I built and balanced it exactly per the instructions.

My GB-Z was delivered in late Aug. last year (2002) after a very lengthy wait !

Just shooting from recall, I feel that 2-3/4" is bit aft to "my liking" only because the wing chord measures 10", and this CG point would be at 27%. On the test flight, I would rather be at 25% which is 2-1/2".

I'm now flying the GP GB-R2 arf and it has a 12" wing chord and it DOES ballance at 2-3/4" which is 23% which is a very good safe starting point.

My "Z" is setup as follows: OS.46FX, w/ Slimline Pitts muffler, APC, 11x6 prop, Higgley Alum Acorn Prop Nut.

All control throws per manual.

Zero ballast needed to Balance.

There was an excellent construction / review article in Model Airplane News as well.

I will confirm later this evening where "exactly" my CG is as my "Z" flies rock solid and very stable.

Brg.
Kerry S.

I balanced mine per the instructions... it flies fine. Keep the throws per the manual... too much elevator will cause it to snap even if it is nose heavy... I tried just to see. I added an OS 70 FS and did not need any balast to balance. I do have higher aileron throws with differential added to keep it smooth and it flies great.

A friend of mine used an OS 52 FS and he had to add 10oz to the motor mount to balance with the battery just behind the firewall. I have video and photos: http://www.webmasterphoto.com/geebee.

I just finished my Great Planes GB two weeks ago an it crashed on the 1st flight... not sure why... search for the Great Planes Gee Bee thread and you can read about it.

John

Dan:

Confirming that I have balanced my "Z" at exactly 2-5/8".

Works great at this lcation and is just a bit more conservative.

Brg.

Well I'll give it a try, it is nose slightly down at 2.75, so that should be pretty close to around 2 5/8.

Thanks,

Dan