Help figure C/G Please

[fishdeth]

Some of you have seen my latest project "Jumpin Jim" (http://www.rcgroups.com/forums/showthread.php?t=347392) and maybe some have not.
I am trying to tap the vast knowledge and experience here on RCGroups.
I am almost ready to power up for a bench test and I have absolutely no idea where to set the C/G on this bird... :confused:

Any help any of you Pro Builders will be greatly appreciated !

Here are some specs that may assist:

Wing span: 37"
Length: 42.5"
Spinner to LE root of top wing: 9"
Root Chord: 10"
Tip Chord: 6"
Positive Stagger: 1.75"
Total root Chord 11.75"


Here are a couple profile pics.

Many thanks,
Jim

[hul]

Jim,

read the article that's posted from post #12 in this thread: http://www.rcgroups.com/forums/showthread.php?t=339401

Deciding on a CG position on a scratch build seems to be the most difficult thing. There are at least 20 different formulas out there and they all give different results.

Good luck, Hans

[Sparky Paul]

For a biplane, this graphical method gives a ball-park answer..
Find the m.a.c. of each wing,
http://perso.wanadoo.fr/scherrer/matthieu/english/mce.html
then put them on a side view..

[Marion]

Sparky's technique worked well for me...

[DLC]

Sparky's technique also works well for me as a starting point. However, I always determine the final C.G. by in-flight testing and C.G. adjustment to get the plane to fly the way I want it to (which is not necessarily the same way another person would want it to fly).