Aileron inboard edge sealing

[Piotr Jaszczuk]

Hi all,

I've found enough info on the internet about advantages of sealing all
control surfaces with mylar tape but I'm struggling a bit to find
anything about benefits of sealing inboard edge of aileron gap with a
plate fitted to wing.
Here is the link to picture that illustrates what I'm talking about
https://picasaweb.google.com/lh/photo/p0zAIcbsLQQs6LsyrxNS_9MTj
NZETYmyPJy0liipFm0?feat=directlink

brgds
Piotrek

[Charlie M. (UH & 002 owner/pilot)]

On Wednesday, March 2, 2016 at 12:30:09 PM UTC-5, Piotr Jaszczuk wrote:
> Hi all,
>
> I've found enough info on the internet about advantages of sealing all
> control surfaces with mylar tape but I'm struggling a bit to find
> anything about benefits of sealing inboard edge of aileron gap with a
> plate fitted to wing.
> Here is the link to picture that illustrates what I'm talking about
> https://picasaweb.google.com/lh/photo/p0zAIcbsLQQs6LsyrxNS_9MTj
> NZETYmyPJy0liipFm0?feat=directlink
>
> brgds
> Piotrek

I believe they're usually called a "fence". As to whether or not they're needed, I think some depends on the wing.

What ship do you have?

[Piotr Jaszczuk]

At 17:50 02 March 2016, Charlie M. UH & 002 owner/pilot wrote:
>
>I believe they're usually called a "fence". As to whether or not they're
>needed, I think some depends on the wing.
>
>What ship do you have?
>

You might be right with the name ;)
My ship is ASW 19B like the one on the picture.

Brgds

[Robert M]

If you do a lot of thermaling they likely will show some benefit in a slightly faster roll rate. However in cruise if you are not flying absolutely in trim they will shed a vortex that just creates drag. It may be better to make the gap as small as practical and have the two sides of the gap smooth and parallel. The ASW-19 wing is very flexable; closing the gap fully or even almost fully will result in binding or even locked ailerons due to the flex of the wing.

Robert Mudd
Composite Aircraft Repair
Moriarty, New Mexico USA.

[Bob Kuykendall]

On Friday, March 4, 2016 at 1:14:43 PM UTC-8, Robert M wrote:

> ...if you are not flying absolutely in trim they will shed a vortex...

Robert raises some good points. The one thing that I'd add is that fences will probably shed a vortex even if you _are_ absolutely in trim. At issue is that airflow on the bottom surface will tend to have a slight outboard component, and that on the top a slight inboard component. These spanwise components will tend to be stronger nearer the tip.

Thanks, Bob K.

[Charlie M. (UH & 002 owner/pilot)]

On Friday, March 4, 2016 at 4:56:49 PM UTC-5, Bob Kuykendall wrote:
> On Friday, March 4, 2016 at 1:14:43 PM UTC-8, Robert M wrote:
>
> > ...if you are not flying absolutely in trim they will shed a vortex...
>
> Robert raises some good points. The one thing that I'd add is that fences will probably shed a vortex even if you _are_ absolutely in trim. At issue is that airflow on the bottom surface will tend to have a slight outboard component, and that on the top a slight inboard component. These spanwise components will tend to be stronger nearer the tip.
>
> Thanks, Bob K.

In engineering speak, "You fix one issue, you FUBAR another issue".
Question is, does the "fix" overwhelm the negative issue?

I can't/won't say, a lot depends on the speed ranges you run it as well as how coordinated you are (lots of side slip add's a lot of drag thus possibly negating any gains in the aileron sealing).....

[[email protected]]

-The ASW-19 wing is very flexable; closing the gap fully or even almost fully will result in binding or even locked ailerons due to the flex of the wing.

- Never seen Asw-19 with a plate sealing inboard edge in any of the US based Asw-19s; had mine in red, numerous times, with substantial wings flexing....and never felt there is ANY need for any modifications to controls. Its a glider with standard certificate, so Schleicher most likely knows better what is needed or isn't.
GK

[[email protected]]

On Friday, March 4, 2016 at 1:14:43 PM UTC-8, Robert M wrote:
> If you do a lot of thermaling they likely will show some benefit in a slightly faster roll rate. However in cruise if you are not flying absolutely in trim they will shed a vortex that just creates drag. It may be better to make the gap as small as practical and have the two sides of the gap smooth and parallel. The ASW-19 wing is very flexable; closing the gap fully or even almost fully will result in binding or even locked ailerons due to the flex of the wing.
>
> Robert Mudd
> Composite Aircraft Repair
> Moriarty, New Mexico USA.

- Never seen Asw-19 with a plate sealing inboard edge in any of the US based Asw-19s; had mine in red, numerous times, with substantial wings flexing....and never felt there is ANY need for any modifications to controls. Its a glider with a standard type certificate, so Schleicher most likely knows better what is required or isn't... What I had also seen is numerous factory "unapproved" modifications to Asw 19, mostly in Europe, and this plate falls in this category.
GK

[Piotr Jaszczuk]

At 03:46 05 March 2016, wrote:
> -The ASW-19 wing is very flexable; closing the gap fully or even
almost
>fu=
>lly will result in binding or even locked ailerons due to the flex of
the
>w=
>ing.=20
>
> - Never seen Asw-19 with a plate sealing inboard edge in any of
the US
>bas=
>ed Asw-19s; had mine in red, numerous times, with substantial
wings
>flexing=
>....and never felt there is ANY need for any modifications to
controls. Its
>=
>a glider with standard certificate, so Schleicher most likely knows
better
>=
>what is needed or isn't.
>GK
>

Thanks guys for all your thoughts. reading all that just convinced
me it isn't worth the effort :) I'm going to keep wings clean of any
gadgets, just proper mylar sealing. What's more the owner of that
19 with fences fitted picture of which I've linked in my original post
is thinking of removing them because hi isn't sure they actually give
something and they are a pain when it comes to fitting the wing
covers after the flight :)

[krasw]

There's an interesting paper on aileroin fences (etc.):

https://tu-dresden.de/die_tu_dresden/fakultaeten/fakultaet_maschinenwesen/ilr/nwk/dateien/berichte/140303_TS.pdf

Bottom line, pair of fences cost 0,25 points L/D.

[Jonathan St. Cloud]

Interesting to note, the JS-1 and Ventus 2 both have fences on inboard flap, fuselage fairing.

[[email protected]]

While I agree Fences dont add much and can be a pain practicaly, there is benefit in closing up the gaps between the edges of the ailerons and the wing. Some birds have pretty big gaps on the sides of the ailerons which make for drag. On my 1-26, i closed these side gaps thus making the wing trailing edge entirely uniform. While theres not much one can do to increase the performance of the 1-26 wing (non laminar airfoil) I experienced a wonderfull gain in aileron effectiveness. I performed the same procedure on my pilatus B4 years ago. On that bird I did get a noticable gain in performance.
Dan

[[email protected]]

On Thursday, March 10, 2016 at 11:49:28 AM UTC-5, wrote:
> While I agree Fences dont add much and can be a pain practicaly, there is benefit in closing up the gaps between the edges of the ailerons and the wing. Some birds have pretty big gaps on the sides of the ailerons which make for drag. On my 1-26, i closed these side gaps thus making the wing trailing edge entirely uniform. While theres not much one can do to increase the performance of the 1-26 wing (non laminar airfoil) I experienced a wonderfull gain in aileron effectiveness. I performed the same procedure on my pilatus B4 years ago. On that bird I did get a noticable gain in performance.
> Dan

Manuals for many glass ships have a specified minimum gap, commonly 1.5mm, between the ends of control surfaces and adjoining parts. Care should be taken to comply with original intent.
FWIW
UH

[[email protected]]

On Thursday, March 10, 2016 at 3:24:01 PM UTC, Jonathan St. Cloud wrote:
> Interesting to note, the JS-1 and Ventus 2 both have fences on inboard flap, fuselage fairing.

JS1s aren't fitted with flaperon fences. There is reference to them on the website but they don't fit them to production aircraft as standard - and weren't offered to me as an option.

[[email protected]]

My end sileron gap seals are made of closed cell foam. They clise the gap virtualy completely and due to being soft foam, has no potential to jam whatsoever, if for some reason they swelled, a single flick of the ailerons would mash them off, its a no brainer.