help needed on CG for flying wing model

bronco · Apr 22, 2002, 08:09 PM

I read some where that flying wing models with reflexed airfoils need to have there cg ahead of the neutral point, like at 15% of the cord. is this right ? my baby blew model is done but i need to balance it , i copied the plan out of a magazine but was unable to get where the cg is,. can any one help?

maciek · Apr 22, 2002, 09:25 PM

Is it a "plank" type wing? I had built a plank wing with a simitar series airfoil, and the C.G. was at 6% if I remember correctly. I've also heard that the C.G. can be further back, which makes the wing less stable (i.e. you can have it enter a spin).

Ragnar · Apr 23, 2002, 02:57 AM

O.K. while we're on the subject, what about Deltas? I'm looking at doing a Mirage, and realise that I will need reflex (Up Elevons) but I don't know where the C of g needs to be. It basically a pefect triangle, so there must be some kind of formula?

Flypaper · Apr 23, 2002, 08:30 AM

Most flying wings and deltas are between 15 and 20%

bronco · Apr 23, 2002, 07:39 PM

it is a plank wing .... so would would 18% be a good starting point? thanks alot in advance .

Flypaper · Apr 24, 2002, 09:12 AM

Just built a double tapered combat wing. Just checked the CG. Its right on 18%. Flies likes It's on rails. If it's a symetrical wing follow the bottom contour of the wing for first flight trim. If It's flat bottom try 1/8 in up elevator trim for starters. Good luck and let us know how it works.
Gord

Apr 22, 2002, 08:09 PM	#1
bronco zen pilot Join Date: Jun 2000 Location: milwaukee WI USA Posts: 157	help needed on CG for flying wing model I read some where that flying wing models with reflexed airfoils need to have there cg ahead of the neutral point, like at 15% of the cord. is this right ? my baby blew model is done but i need to balance it , i copied the plan out of a magazine but was unable to get where the cg is,. can any one help?

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Apr 22, 2002, 09:25 PM	#2
maciek Registered User Join Date: Feb 2001 Location: Worcester, Ma, USA Posts: 273	Is it a "plank" type wing? I had built a plank wing with a simitar series airfoil, and the C.G. was at 6% if I remember correctly. I've also heard that the C.G. can be further back, which makes the wing less stable (i.e. you can have it enter a spin).

Apr 23, 2002, 02:57 AM	#3
Ragnar Oz Member Join Date: Nov 2001 Location: Near Mallala, South Oz Posts: 161	O.K. while we're on the subject, what about Deltas? I'm looking at doing a Mirage, and realise that I will need reflex (Up Elevons) but I don't know where the C of g needs to be. It basically a pefect triangle, so there must be some kind of formula?

Apr 23, 2002, 08:30 AM	#4
Flypaper Registered User Join Date: Nov 2000 Location: kingston Ont, Canada. Posts: 33	Most flying wings and deltas are between 15 and 20%

Apr 23, 2002, 07:39 PM	#5
bronco zen pilot Join Date: Jun 2000 Location: milwaukee WI USA Posts: 157	it is a plank wing .... so would would 18% be a good starting point? thanks alot in advance .

Apr 24, 2002, 09:12 AM	#6
Flypaper Registered User Join Date: Nov 2000 Location: kingston Ont, Canada. Posts: 33	Just built a double tapered combat wing. Just checked the CG. Its right on 18%. Flies likes It's on rails. If it's a symetrical wing follow the bottom contour of the wing for first flight trim. If It's flat bottom try 1/8 in up elevator trim for starters. Good luck and let us know how it works. Gord