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Old Oct 20, 2013, 01:40 PM
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new hor. stabilisator- same performance?

Hi
Does changing horizontal stabilistor (to find new but not orginal) can change DLG performance.
I guess surface will not be the same but very similar on new hor. stab..
Any experience with new non original hor. stab and possible changing in performance?
thx
boris
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Last edited by vigli; Oct 20, 2013 at 01:48 PM.
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Old Oct 20, 2013, 01:51 PM
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United States, MD, Baltimore
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Tail groups have a massive effect on airframe performance. There is a reason people will pay for and wait for swindell tails. There are plenty of high performance tail groups available. Depending on what you are flying with now you may see huge improvements to launch height/range/pitch damping. I changed out the balsa tails on my old taboo and it was a whole new machine.
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Old Oct 20, 2013, 02:32 PM
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My hor. stab. is very light.
Question would be does small difference in surface on new hor. stab. can change performance. Weight ....let say is the same...
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Old Oct 20, 2013, 02:46 PM
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Surface area is one thing. Airfoil is another. Quality of construction for the sharpest TE and smoothest LE is yet another. I am not an aero guy but if you want the best answer tell us what you are flying and what you are looking at. Tail weight is bad but I would rather have a slightly heavier high performance set than a lighter flat/draggy set.
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Old Oct 20, 2013, 03:02 PM
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I fly Turbo07.
I was just wondering about changing tail.
It is warp little bit but I will turn back on the hot- I do that before.
Model has very long tail and relative small h.stab
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Old Oct 20, 2013, 06:18 PM
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Old Oct 20, 2013, 06:39 PM
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boris:

I have campaigned two Blaster 3s for several years, now. I traded out the original tail sets for Swindells, and since then have replaced one Swindell horizontal tail for a foam/kevlar tail of different planform and section. The Swindell tails contributed (I believe, through considerable experience in more than two years of competition) to significantly improved performance. They were thinner, although not smoother, than the originals.

Part of the perceived improvement came from (I believe) to the fact that I removed the large V-mount of the all-moving tail, and replaced it with a shorter, lighter, thinner mount for a fixed tail with elevator.

At the Reynolds numbers our airplanes fly at, I'm not sure surface finish makes all that much difference, but I don't really know.

Yours, Greg
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Old Oct 21, 2013, 10:07 AM
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David
I was thiking about pitch respon.

Greg, does Your new and old hor. stab.has same surface?
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Last edited by vigli; Oct 21, 2013 at 12:13 PM.
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Old Oct 21, 2013, 12:07 PM
G_T
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Shape and size matter more than airfoil for the horizontal stabilizer, within reason. This is not counting flat plate tails or poor airfoil choices which suffer from deadband - tails such as that should just be replaced IMHO. The size and shape is going to set the stability characteristics. The airfoil choice and % movable surface sets the efficiency (greater % moving -> higher efficiency when moved. In this case, higher efficiency means less drag).

Additionally, smaller tails have less drag (obviously) but also have additional drag reduction benefit due to the resulting vertical loading of the horizontal tail being reduced or going negative. The horizontal tail sits in the wing's downwash. So if the tail is lifting, it tries to lift upwards and backwards, increasing the drag. A small tail tries to press down a little. Because of the tilt of the freestream it sees due to the downwash of the wing, some of its negative lift converts to forwards thrust cancelling some of its drag. The minus of small tails of course is greater sensitivity to CG and reduced pitch damping. Since CG setting is often best optimized for the conditions, that gets more critical with small tails.

Gerald
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Old Oct 21, 2013, 11:08 PM
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Could you recommend replacement tails for a topsky 3?

thanks,
Hugh
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Old Oct 23, 2013, 08:19 AM
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Quote:
Originally Posted by Planeur View Post
Could you recommend replacement tails for a topsky 3?

thanks,
Hugh

I would also like to know if Swindell tails would be a noticeable improvement on the T.Sky 3 (or any other, for that matter).
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