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Old Jan 22, 2013, 04:14 PM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
4,406 Posts
Question
Flying Stabs, worth the effort?

With my Sabre build on hold for awhile, due to finishing costs, I needed a new project with a lower price tag! The plus is, I already have most of the materials.

The project I want to model has flying stabs, but could just as well have elevators. There goes the "cool" factor. The question is, Are they worth the trouble?

My biggest concern is balancing them, and servo size. A pic of pivot point, is at 40.96% of root cord, from the manufactures web site, and drawn out shape of stab, approx 65 sq in.
Dimentions are scaled size for intended project. I have looked at other builds, F-18,F-15's but not to much info . If I choose elevators, what % of area should they be? I don't know much on them, Flying Stabs, so any info is helpfull.
TIA , Mark
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Old Jan 22, 2013, 04:24 PM
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unclecrash's Avatar
white lake michigan
Joined Oct 2004
3,648 Posts
If it were me I would just do the elevator's. If you are looking to build it quick at a low budget.
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Old Jan 22, 2013, 04:59 PM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
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unclecrash, the more I think about it, I am inclined to agree. Looking more at a simple set-up, as they will have some anhedral also.

If I recall correctly, back in the late 80's , Andy Lenon had a monthly column on plane design. It seems to me, he had used a certain percentage of total stab area for the elevators. Does anyone know what % it should be?
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Old Jan 22, 2013, 05:06 PM
It wasn't me...
DanSavage's Avatar
Trabuco Canyon, CA
Joined Nov 2000
4,540 Posts
Mark,

Remember that flying stabs were created for pitch control at supersonic flight. Since your model is strictly sub-sonic, stabilizer/elevators are actually more efficient. The main reason to use flying stabs on a model are for scale-looks.

That said, if you want to use flying stabs, you should place the pivot point at 20% of the MAC for the flying stab. If you place it any further back, then the stab will want to 'hunt' or oscillate up and down which will result in imprecise operation.
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Old Jan 22, 2013, 05:19 PM
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unclecrash's Avatar
white lake michigan
Joined Oct 2004
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Quote:
Originally Posted by CoolerByTheLake View Post
unclecrash, the more I think about it, I am inclined to agree. Looking more at a simple set-up, as they will have some anhedral also.

If I recall correctly, back in the late 80's , Andy Lenon had a monthly column on plane design. It seems to me, he had used a certain percentage of total stab area for the elevators. Does anyone know what % it should be?
You might send P901P901 a pm he has all kinds of programs for calculating different stuff.
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Old Jan 22, 2013, 06:08 PM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
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Thanks Dan, no need to get to complex in this build. Tha anhedral in the stabs will provide the look I want anyway. Elevators are by far easier and simple to set up.

unclecrash, I will do just that.
"You might send P901P901 a pm he has all kinds of programs for calculating different stuff."
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Old Jan 22, 2013, 08:23 PM
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p901P901's Avatar
United States, CA, Lancaster
Joined Jan 2009
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Quote:
Originally Posted by CoolerByTheLake View Post
With my Sabre build on hold for awhile, due to finishing costs, I needed a new project with a lower price tag! The plus is, I already have most of the materials.

The project I want to model has flying stabs, but could just as well have elevators. There goes the "cool" factor. The question is, Are they worth the trouble?

My biggest concern is balancing them, and servo size. A pic of pivot point, is at 40.96% of root cord, from the manufactures web site, and drawn out shape of stab, approx 65 sq in.
Dimentions are scaled size for intended project. I have looked at other builds, F-18,F-15's but not to much info . If I choose elevators, what % of area should they be? I don't know much on them, Flying Stabs, so any info is helpfull.
TIA , Mark
Your stab area is 67.17 sq in. Go 35% of that for the elevator. Your elevator should be 22.45 sq in. If you what the hinge line tracking the TE then go 2.88" from TE.
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Last edited by p901P901; Jan 24, 2013 at 12:04 AM. Reason: Stab
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Old Jan 22, 2013, 09:13 PM
“Do it Right The First Time!”
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
4,406 Posts
p901P901 Thanks so much. I was close on the area. I had an old set of plans for a Y/A Starfire and measured the stab area vs elevator area, it came out at 32.5% My calcs , although somewhat off , gave me 21.13sq in. Close but no cigar! Now I'm back in buisness.
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