FIGURING CG????????

[rede2fly]

ok i have a 2 meter sailplane and there were no instructions that came with this. very common in sailplanes. at least with good sailplanes. ok the wing span is 210mm but narrows at the tip. meaning not equal to the tips. so i figured apx 53mm would be the point this is figuring 25%. to go at 1/3rd % would be 72mm. i spoke with someone else who has one and was told 92mm is the cg. how can i figure this exactly?? any help?????

[50%plane]

If it's a common built up plane, like the Goldberg Gentle Lady, or Sig Riser, then you would balance it on the spar. Other that, balance it about 25-33% back on the wing root as you noted in your post.


50%

[rede2fly]

no its not common. it comes from bul-gary-ah. thats the best i can manage at this moment. its all moulded and i cant be wrong. or it will be quite expensive. do you have the correct formula?? i shure would be gratefull.. mr rutan are you out there you guys know who iam talking about

[Fearless Flyer]

The CG point would most likely be the thickest part of the wing.
Do you know the name of the plane so you can research it by manufacturer and maybe contact them on the topic?

[rede2fly]

i know the name its sold under in the usa but, its never the same name out of the usa. i ran a search on the net.ok i found something on this plane. but i would still would like the formula to figure this out.. thanks guys

[adrian]

[adrian]

http://www.palosrc.com/instructors/cg.htm - this is a CG calculator - check it out!!

[Edge 540]

Yeah, 25-30% MAC.

[rede2fly]

	Quote: Originally Posted by adrian
	http://www.palosrc.com/instructors/cg.htm - this is a CG calculator - check it out!!

thanks holms. no really thanks adrian. very cool this should be posted on the giants somewhere for everyone to see

[adrian]

	Quote: Originally Posted by rede2fly
	thanks holms. no really thanks adrian. very cool this should be posted on the giants somewhere for everyone to see

welcome - interesting stuff on the site - used it for years!!!

[wizard]

That is a great way to figure CG For most airplanes. Many sailplanes are balanced up to 40% of the MAC. There are some great articles here on balancing sailplanes. http://www.mrcss.org/gordyarticles.php

Like with any aircraft. The CG will be different depending on pilot taste. With the CG more forward the aircraft will be tamer, with the CG more to the rear the aircraft will be more responsive. If the CG is too far to the rear the aircraft will be uncontrollable.