CG point
 

I just purchased a Sport-Air 40 from a friend who has passed away. I was not able to find the manual for it. I am looking for the CG point for this plane. I have checked Northeast Aerodynamics for a pdf file but none. If anyone has the information please let me know. If not I will start at 25% from the leading edge of the wing.

Thanks
Bob

RE: CG point
 

I don't know the plane, but if it is a flat bottom or a semi symetrical wing, 25% will be a good place to start for sure.



Here is a CG calculator. just use 25% (or what ever you want) for the % MAC. and you will get a measurement.

http://www.palosrc.com/instructors/cg.htm

RE: CG point
 

Bob,

I bought one of these that was hanging from the ceiling at the LHS. It was old, It was a step up from the LT 40 I was learning on. The first flight with her was sweet, about 2 degrees of right thrust on the OS45F engine, she ground handled like a dream, I was doing stall turns, rolls and loops. I brought her in and gassed her up and while poking holes in the sky my flying buddy goaded me into going inverted even though I didn't think I was ready. She handled great and I was almost comfortable inverted, then ...I made a pass across the field and relaxed on the down elevator a little and she dipped down. You can guess how my reflexes reacted since it was my first inverted flight. Balsa dust and a very sad day for me. You will really enjoy this plane. Before I put her up I e-mailed Northeast Aerodynamics and below is the reply I received. Mine balanced right on the thickest part of the wing on the spar. Hope this helps.

rod
----------------------------------------------------------------
Rod,


Elevator = 7/16" up/down
Rudder = 1-1/4" right/left
Ailerons = 3/16" up/down
Nose wheel = 1/4" left/right


The balance point on the Sport-Air .40 is anywhere between 25% and 35% of the wing chord (by the way this is correct for any plank style wing). I would recommend that you start at 30% then you can move it forward or rearward depending on your flying skills/taste.


As for thrust, 0-degrees up/down and 0-degrees left/right. If you are using a three blade prop you might find a need for a little right thrust. However, start at 0-degrees and fly the plane. Use a trim chart to detemine in flight if you need any corrections.


Have fun and fly safe!


John
Northeast Aerodynamics Inc.


---------- Original Message ----------------------------------
From: Rodney Cantwell
Date: Tue, 16 Sep 2003 10:01:13 -0500


I purchased a second hand Sport-Air 40 and had to do a little repair to the
control linkages and engine/nose wheel mount before trying to get it in the
air. It would be very helpful for me if I could get the correct balance
point (CG) and the engine offsets both right and down. I think I am close
and I'm ready to take it to the field but it would give me great peace of
mind to know my estimates are close before I do any un repairable damage to
such a nice plane.


Any help you could give me would be greatly appreciated


rod

RE: CG point
 

Rod, thank you for the information. Now I am all set and am looking forwarded to flying the Sport-Air 40.

Thanks
Bob