Hi,

Hope someone can answer these 2 questions

1) I have an ali spinner on one of my spitfires, its lookign worse for wear with scracthes etc on it (i know im fussy) but is thier anyway to clean these off or a way to just make it look better.

2) Ive brought some planes of ebay already built and i have no means of telling where the C&G point should be, is thier a general rule of the thumb to where it should be or do i just hazard a guess ?

Thx in advance for any info

When in doubt, start at 25% MAC and slowly move back... you usually end up on the main wing spar.

MAC is the AVERAGE chord. Easy to find for a straight un-tapered wing (every rib is MAC), an unnecessary source of confusion for many people. any HS geometry instructor can fnd an average chord. then you go 25% from front to rear on that line... you are at 25% MAC

Another way to look at it... find the line where 25% of the wing is in front and 75% behind that line... that is 25% MAC.

Try to find pads called ScotchBrite, about 1/4" (7mm) thick and looks like real dense furnace filter. They come in red, green or gray depending on the courseness rating. Most hardware stores will carry it.

These are couple of good cg calc. sites
http://www.palosrc.com/instructors/cg.htm

http://www.lvrcs.com/content/index.php

If you are looking for a MAC calculator, I have two!
http://www.geistware.com/rcmodeling/cg_calc.htm#mac