FIGURING CG????????

rede2fly · 12-26-2006, 09:15 PM

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 · 12-26-2006, 09:19 PM

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 · 12-26-2006, 09:28 PM

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 · 12-26-2006, 09:35 PM

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 · 12-26-2006, 09:39 PM

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 · 12-27-2006, 05:35 AM

adrian · 12-27-2006, 05:41 AM

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

Edge 540 · 12-27-2006, 03:07 PM

Yeah, 25-30% MAC.

rede2fly · 12-27-2006, 05:10 PM

	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 · 12-28-2006, 02:16 AM

	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 · 12-28-2006, 04:00 AM

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.

12-26-2006, 09:15 PM	#1 (permalink)
rede2fly GRAVITY SUCKS Join Date: Jan 2006 Location: florida Posts: 2,045	FIGURING CG???????? 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????? __________________ dont tell me how to do it....... show me how FLORIDA FREESTYLE AEROBATIC ASSOCIATION

12-26-2006, 09:19 PM	#2 (permalink)
50%plane I lay down the law here Join Date: Jan 2006 Location: Static Display Age: 21 Posts: 7,733 Blog Entries: 67 Awards Showcase Total Awards: 3	Re: FIGURING CG???????? 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% __________________ Christopher Todd Thanks to my many sponsors for their dedication to benefit my pursuit of this wonderful hobby: Hardwork, a job, and Visa Charter Member of Team F.O.A.M. Fellowship Of Antagonistic Modelers JR, Futaba, Hitec, Brison, WildHare, Aeroworks, Vess Hey Fatty, lay off the McDonalds and go to the gym so you don't look like that cow that supposedly became your Big Mac!

12-26-2006, 09:28 PM	#3 (permalink)
rede2fly GRAVITY SUCKS Join Date: Jan 2006 Location: florida Posts: 2,045	Re: FIGURING CG???????? 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 __________________ dont tell me how to do it....... show me how FLORIDA FREESTYLE AEROBATIC ASSOCIATION Last edited by rede2fly; 12-26-2006 at 09:36 PM.

12-26-2006, 09:35 PM	#4 (permalink)
Fearless Flyer Bad Mother Hucker!!!!!!!! Join Date: Jan 2006 Location: Casselberry, Florida Age: 17 Posts: 880 Awards Showcase Total Awards: 1	Re: FIGURING CG???????? 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? __________________ http://www.freewebs.com/team_fearless/index.htm Team Fearless Official Site www.teamfearlessrc.com TEAM GOLDEN SKIES http://WWW.GOLDENSKIESRC.COM C.J.

12-26-2006, 09:39 PM	#5 (permalink)
rede2fly GRAVITY SUCKS Join Date: Jan 2006 Location: florida Posts: 2,045	Re: FIGURING CG???????? 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 __________________ dont tell me how to do it....... show me how FLORIDA FREESTYLE AEROBATIC ASSOCIATION


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12-27-2006, 05:41 AM	#7 (permalink)
adrian Bad-ass Super Contributer! Join Date: Jan 2006 Location: TEL AVIV Age: 20 Posts: 2,406 Blog Entries: 11	Re: FIGURING CG???????? http://www.palosrc.com/instructors/cg.htm - this is a CG calculator - check it out!! __________________ My sponsors : *Team "Shalat Rachok" Israel* Spektrum radios/Horizon Hobbies my blog http://janstrydom.blogspot.com

12-27-2006, 03:07 PM	#8 (permalink)
Edge 540 Bad-ass Super Contributer! Join Date: Jan 2006 Location: Dayton Ohio Posts: 1,618	Re: FIGURING CG???????? Yeah, 25-30% MAC.

12-28-2006, 04:00 AM	#11 (permalink)
wizard It will fly!!! Join Date: Jan 2006 Location: Washington, Indiana Age: 44 Posts: 7,722 Blog Entries: 12 Awards Showcase Total Awards: 2	Re: FIGURING CG???????? 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. __________________ Prevent Darwinism become a paramedic!!! Never try to teach a pig to sing! It wastes your time and it annoys the pig!!! Powered by Jim Beam

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