Hi guys, Im building a Black Horse Model 'Bravo 303'

The instructions call for a C of G 14mm Back from the leading edge, where as mine is balancing at about 14cm back. The instructions have been crap the whole way through, and dont know if the guys making this kit where high on crack when saying its 14mm (it just feels wrong, I need the weight of my cordless drill to make it balance there)

How can I determine by myself where C of G should be???. I dont have a truck load of led......

Thanks
Byron

I don't know that ship, but for a typical pattern type ship, they balance close to the neutral point, which is typically around 40%-50% of mean aerodynamic chord (MAC.) So balance should be around 30%-40% of mean aerodynamic chord. I'd start toward the front of that range, say 30%-35%. If you don't know how to calculate MAC, Geistware, a member on RCU, has one on his webpage. http://www.geistware.com/rcmodeling/cg_calc.htm#mac

14 mm is only about 9/16 of an inch. That doesn't sound right to me, unless the wing is highly swept back and the measurement is taken at the wing tips. It's possible that they meant 14 cm all along and the mm was a misprint.
If 14 cm back from the leading edge is about 30% of the mean aerodynamic chord (MAC) then that's what I would balance for.
The leading edge of this plane is swept back a little so it is also very important to find where to measure this, near the fuselage or at the wing tips?

Bobro, By all means do the MAC calculations and start out at about 30%-35% point on the MAC line. After you get the CG at this point, make sure it is also forward of the wing high point. This is a safe starting point for the CG. After you fly the plane for a while you can adjust the CG to your liking.

Good luck

Oldbob

Hi!
14 mm is not correct! Must be a miss-spelling.
Show us wing picture from above, an I will show where the C of G should be (most of the time 25-30% of the wing cord).

Regards!
Jan K
Sweden

Hi guys, thanks for all your help. I did the calculations with a mac 30% and got a CG of 15.74cm back from the leading edge, and yes oldbob its infront of the hight point on my wing. This sounds and looks a little more normal to me!

If i take off and its tail heavy Im gonna blame you guys, haha

Thanks for the help.
b0bro

Trust me, it wont be.

You will get the BEST pattern information at the official website www.nsrca.org.

And/or the pattern forum here at RCU. Some of the best pattern builders and pilots in the WORLD frequent the site and will give you more help than you need. http://www.rcuniverse.com/forum/forumid_101/tt.htm

b0bro,

I have found the same problem with the Black Horse ARF's i have put together 2 Black horse kits and had the same problem on both of them with the instructions not clear enough for one and the covering on both planes was not put on very well at all, my 3rd plane i just put together has been fantastic was made by PHOENIX MODELS and the covering and instructions have been very good and easy to understand so i think for me ill continue to get PHOENIX MODEL ARF's in the future.

Happy Flying to all
Paul