My airfoil Tail

For general discussion of the Just Aircraft family of aircraft.
Includes: Highlander, Escapade, Summit and SuperSTOL.
Post Reply
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

My airfoil Tail

Post by BDA »

This is my Airfoil horizonal stabilizer.

I bought the factory airfoil shaped horizontal stabilizers that have a very large airfoil on the bottom, and a very small airfoil on top and modified them as follows.

I cut out the 2 small airfoil ribs on the top and replaced them with bent tube ribs made from a NACA symetrical airfoil template. Chris Wallen made the bent tube ribs for me with my template.

Then I added a rib to each end that matched that profile. So I ended up with 4 ribs on each side instead of the 2 from the factory.

But the stretched sheet test showed too much scalloping for my taste - thats why the tails that Chris buils have 6 ribs.

So I added an aluminum leading edge.
You do not have the required permissions to view the files attached to this post.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

My reason for all the extra work:

Paul asked a good question:
“What possessed you to redo the tail feathers airfoil?
You hadn’t even tested it in flight?”

This was the factory airfoil tail - it was not symetrical, more lift on the bottom than the top.
I flew the factory plane with it.

I am going to fly mine loaded heavy and need to get the tail out of the mud with a load.
= more lift on the top.

Thats why I made the aluminum symetrical ribs 2 years ago.
But when Chris Wallen made these beautiful tube ribs with my template - I couldnt resist!
You do not have the required permissions to view the files attached to this post.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
AV8R Paul
Veteran Member
Posts: 578
Joined: Sun Mar 22, 2015 7:49 pm
Location: Garland, Texas

Re: My airfoil Tail

Post by AV8R Paul »

The leading edge will help dramatically with getting rid of the scalloping. My airfoil was a NACA0008 airfoil, I’m guessing but yours looks like an NACA0010 OR NACA0012. It should perform well. Symmetrical makes more sense to me relative to the design and function of the Horizontal Stabilizer. Just my personal opinion.

I went and tested the lift of the tail, I held the breaks, full power, and picked the tail. I could have easily nosed the plane over.

If I were you I would bond the leading edge to the ribs using Hysol. I did a leading edge on the vertical stabilizer, and the Horizontal because I didn’t want the scalloping.
AV8R Paul
Certified Light Sport Repairman LSRM-A
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

Thanks Paul
Thats good info, same test with weight in it?

The airfoil I started with 2 years ago was a 0012, but when match the ribs the factory put on the bottom side they are 21% chord in thickness so would be more like a NACA 0021

And that is really thick - looks like maybe too much, but that profile gives the nose of the stabilizer a nice round transition surface no matter what angle the direction of the air is in relation to the tail plane.
And that is what is required for very nose high, slow speed pitch control.

So it will be an experiment - will be very interesting to see if it is any better in slow flight, and how much more draggy it will be.
You do not have the required permissions to view the files attached to this post.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

Sorry the pics are not in sequence

Had to resize
You do not have the required permissions to view the files attached to this post.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

More sheet metal
You do not have the required permissions to view the files attached to this post.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

With fabric
You do not have the required permissions to view the files attached to this post.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

Covered the fancy elevator balance doodads that these goofy new tail feathers come with - then didnt have anywhere to wrap the fabric around to finish the ends.

Sooooo I fabbed up an aluminum angle with nutplates that attaches to the back side of the tabs for the fence. One for each side.
You do not have the required permissions to view the files attached to this post.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
kenryan
Veteran Member
Posts: 342
Joined: Sat Jan 01, 2011 3:46 pm
Location: anchorage, ak

Re: My airfoil Tail

Post by kenryan »

Are those factory tail feathers?
Super Stol Kit #299
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

No, They are not “factory” anymore.

Oringinally they were the new airfoil feathers they sell, but I added more airfoil to the top to make it a symetrical airfoil.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

With elevator

Looks funny w out the rudder
You do not have the required permissions to view the files attached to this post.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

Well its time to post a performance report on this airfoil tail.

This mod was the most concern for me as it has not been tested by anyone else that I know of.

I put a great deal of research and calculation into this and was pretty sure it was what I wanted but you never know till you know.

So I have almost 2 hours on it now, about 1/2 hour was testing with it tied to a forklift just in case it did something unexpected. Nothing exciting happened so I lit a fire and blasted off!!

To say it is all I hoped for would be an understatement.

When I let off brakes and push the throttle, I can feel the tail get lighter, when I let the stick of the rear stop, the plane leaves the ground. I never get the stick all the way forward. It just flys immediately.

I have a slight amount of stick force forward which was expected and just a little trim takes that away, but that is empty with half fuel, I think with weight in it I would be neutral.

This is exactly what I wanted, more lift for weight in the tail and faster tail lift for take off.

I did not like the lack of elevator authority on first throttle at takeoff on the factory plane.

So far, I couldnt be happier... much more testing to do.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
User avatar
CanadianSheepHunter
Veteran Member
Posts: 678
Joined: Thu Feb 26, 2015 1:05 pm

Re: My airfoil Tail

Post by CanadianSheepHunter »

Right On !
PPGFlyer
New Member
Posts: 3
Joined: Wed Aug 07, 2019 11:09 pm

Re: My airfoil Tail

Post by PPGFlyer »

Glad to hear! I did a very similar mod as you. Chris Wallen welded his airfoil ribs on the horizontals. Welded a longer bushing for the flying wires needed because of the leading edge skins. Also made the trim tab bigger for more area like the the factory flying tail option.
IMG_4140.JPG
IMG_4242.JPG
IMG_4321.JPG
IMG_4236.JPG
IMG_0819.JPG
IMG_4141.JPG
IMG_4006.JPG
You do not have the required permissions to view the files attached to this post.
User avatar
BDA
Veteran Member
Posts: 707
Joined: Mon Aug 22, 2016 11:25 am
Location: Kenai Alaska

Re: My airfoil Tail

Post by BDA »

Just in case some of you dont see this in the gap seal thread.

The gap seals make this airfoil work MUCH BETTER.

They seam to multiply the airfoil lift - that is what it feels like.
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
Post Reply

Return to “Just Aircraft”