mark d. fain

Anyone out there flying a Super Kaos? Where did you put your CG?

I am just finishing up a Super Kaos 90 ( w/ Saito 180) from the M.A.N. plans
and hope to test fly Sunday. The construction article showed the
recommended CG to be behind the airfoil high point by a fair bit. I checked
the CG on a set of plans for the original Super Kaos and it also had the CG
well aft of the root rib's high point. In the past I have always balanced
at the rib's high point (center of spar.) Does this aft CG seem correct?

Any thoughts will be appreciated.

Mark D. Fain

skylane42

balance it on the spar... or slightly forward of it.

ecregger

While the trailing edge sweep is a little more (in number of degrees)
than the leading edge sweep, which would locate the CG further
rearward than the root rib would indicate, I still went with the high
point of the wing on my Kaos models and then moved it back as needed.

I can't see how it would be that much further back than normal, even
with more sweep in the trailing edge.

Please write us a mini review of your model and post it here. TIA

Ed Cregger

mark d. fain

Last night I tried the "graphical" method of CG determination. I.E. on a
planform view of the wing from the high point of the root rib draw vertical
lines equal to the chord dimension. From the high point of the chord draw
vertical lines equal to the root dimension. Cross connect the endpoints, and
from the intersection draw a line perpendicular to the root rib. This is the
CG.

I posted a copy of the drawing over at
http://www.rcflying.net/forums/showthread.php?s=9b8108f3f7691f85d34afc6b9d914b1a&threadid=4979

In my case this method gives a CG only about 1/2" further back than the
center of the spar. It is also exactly where the magazine article showed
it. I am currently about 1/2 way between these two points (i.e. at rear
edge of the spar). I would think that would be in the safe zone on a 16"
wing chord. The plane has a 24 oz. tank which is behind the firewall, as in
the original, so I'm definitely going to be nose heavy until the last 2 or 3
OZ. of fuel, even with the CG measured at the center of the spar.

skylane42

First of all are you sure that is the CG location or the location of the
Average Chord? if you add the root chord and the tip chord and divide by 2
that will give you the average chord. Your CG will be the % of that chord. IE
28% of the average chord. Sounds like the back edge of the spar is about
where you want to be. Try plugging your dimensions into the calculator at
http://www.palosrc.com/instructors/cg.htm

ed cregger

Doh! I just realized that I got it backwards.

Anyway, the main spar worked fine for my Kaos models.

Ed Cregger

news:<OPacb.11456$Ly2.1804219@cletus.bright.net>.. .

skylane42

Ya know, I don`t think I`ve ever seen a RC model where the CG isn`t really
really close to the main spar.

paul mcintosh

I have owned several versions of the plane and all balanaced a d flew great
with the CG at the spar.

BTW, if the CG is at the 30% point, the ratio of LE to TE taper would be
1:2. That means the LE taper would be half or the TE taper. That keeps the
CG at the same distance from the MAC all the way out to the tip.

--
Paul McIntosh
Desert Sky Model Aviation
http://fly.mcintoshcentral.com

mark d. fain

The difference between the CG point the article recommended and the more
conventional "Center-of-Spar" point is 1/2". I actually ran into the man


won't let me log in so I can post the question.

I just installed the custom spinner adapter (steel) I had to turn and
rechecked the balance. I am now 1/8" behind the spar center. On a 16"
chord this should be well inside the safe zone. Mark
"Ed Cregger" <ecregger@hotmail.com> wrote in message news:bkvf1r032c@enews2.newsguy.com...