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Design => Stunt design => Topic started by: Jim Roselle on July 10, 2013, 10:42:31 PM

Title: Elevator to stabilizer ratio
Post by: Jim Roselle on July 10, 2013, 10:42:31 PM: New to the forum, lots of great information here! My question is in regards to the elevator. I gather from other post that the stab/elevator should be 20-25% of the wing area. What percentage of the stab/elevator assembly should the elevator be?

Thanks in advance,
Jim
Title: Re: Elevator to stabilizer ratio
Post by: Brett Buck on July 10, 2013, 10:58:01 PM: Quote from: Jim Roselle on July 10, 2013, 10:42:31 PM
New to the forum, lots of great information here! My question is in regards to the elevator. I gather from other post that the stab/elevator should be 20-25% of the wing area. What percentage of the stab/elevator assembly should the elevator be?

The total area of the stab/elevator needs to be bigger than 20% in most cases, at least by current standards.

The ratio of elevator is (like everything else) a debatable point. I use ~65/35 stab/elevator and most everyone is in the range of 55/45 to 65/35. I also strongly recommend a low aspect ratio 3.5:1 to 4.5:1 with a relatively thin airfoil.

Brett
Title: Re: Elevator to stabilizer ratio
Post by: RandySmith on July 11, 2013, 12:05:04 AM: Quote from: Jim Roselle on July 10, 2013, 10:42:31 PM
New to the forum, lots of great information here! My question is in regards to the elevator. I gather from other post that the stab/elevator should be 20-25% of the wing area. What percentage of the stab/elevator assembly should the elevator be?

Thanks in advance,
Jim

HI Jim

The Katana and Exel I have flown for the past 14 years have been 25% of the wing area, and are 4.24 A/R , it is close to the 55% 45% stab to elevator
My piped SV-11 is close to the same
This works very well for me. Others mileage may vary.
I also flew a High A/R tail on my VECTRA with good results
I will tell you it is much easier to built a stiffer Stab and Elev with a lower A?R

Regards
Randy
Title: Re: Elevator to stabilizer ratio
Post by: Jim Roselle on July 11, 2013, 03:51:22 PM: Thanks for the info guys.

Jim
Title: Re: Elevator to stabilizer ratio
Post by: RandySmith on July 11, 2013, 05:31:05 PM: Seems to work better if the LE of the stab is pointy instead of blunt also

Randy
Title: Re: Elevator to stabilizer ratio
Post by: FLOYD CARTER on August 03, 2013, 11:48:38 AM: I have seen some stab/elevator designs where the stab was 1/2" and the elevator 3/8". Or, perhaps 3/8" and 1/4". Anyway, there seems to be some aerodynamic reason to make the stab thicker than the elevator. Or is it just for strength?
Floyd
Title: Re: Elevator to stabilizer ratio
Post by: Brett Buck on August 03, 2013, 08:24:54 PM: Quote from: FLOYD CARTER on August 03, 2013, 11:48:38 AM
I have seen some stab/elevator designs where the stab was 1/2" and the elevator 3/8". Or, perhaps 3/8" and 1/4". Anyway, there seems to be some aerodynamic reason to make the stab thicker than the elevator. Or is it just for strength?
Floyd

No, the theory is to "desensitze it around neutral". The theory is that you "block" the relative wind so that the elevator can move a little before anything happens. At Mach 10, it might actually do that, what it does at 60 mph is unclear, aside from making the elevator run in turbulence all the time.

Mine is exactly conformal to the stab (made in one piece and then cut apart) and has all the corners rounded to minimize the turbulence. I think you don't want it to desensitize it around neutral and I doubt that making the stab thicker actually accomplishes that.

Brett
Title: Re: Elevator to stabilizer ratio
Post by: FLOYD CARTER on August 04, 2013, 10:01:08 AM: Well, that's good news. I usually build stab and elevator using all the same thickness balsa. Normally all built-up from 3/8" stock.

Floyd