DragonHeart

Hi Guys,

I wonder if anyone can give me some advice on this plane in the pic, ive just built it its a Segull Models P51-D and all i have left to do is to balance it. The instructions are pretty lame all they state is 7cm back from the leading edge..................... but as with a mustang it has a wing center section that slopes forward quite a bit as can be seen below which is 5cm in length soo do i set the gauge up at 7cm plus the 5 making 12cm back ?????? or can i do it from the normal leading edge which is away from the fuse ?????????

Help plz as i hope to get this in the air soon

PS : I posted this post in the warbirds section soo sorry for the double post but no one replyed or could help

Thx in advance for any help...........

FHHuber

With the 5 cm size reference for that small sharply tapered section.... I would say to balance it at 12 cm back at the root, or 5 cm back at where the sharp taper ends.

It is possible... that the 5 cm back reference is from the leading edge at the wingtip... which would be even further back... (and would make more sense to me because the LE of the Mustang wing should sweep back enough that the above could have the CG forward of the LE at the tip....)

Look up in the Aerodynamics forum discussions about "MAC" MAC is mean aerodynamic chord. You want to start with the CG close to 25% MAC. There is an easy way to get this measurment for anything other than an eliptical wing (like a Spitfire) And the drawng for the method has been posted many times in that forum.

DBCherry

My Feedback: (4)

I think this is what FH was referring to. It's a very easy way of determining MAC, and from that the correct CG.

I think using this, I would take the mid point of that root chord rather than the full chord though.
Dennis-