Wing tie-down kit

[JJ Sinclair]

Padded aluminum cusp that slips over trailing edge with web strap that
goes over leading edge then down to cable or stake with hooks and
ratchet for tightning. Can be easily carried in ship. E-mail me for
picture.........see Williams Soaring, set of two for $125 + shipping.
JJ

[Rex]

See this in detail at WSC online store
http://store.williamssoaring.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=WSP&Product_Code=06JJTIEDOWN&Category_Code=SP

Great device produced by JJ.

Regards,
Rex Mayes
Williams Soaring Center

[Pete Smith]

At 01:48 04 August 2008, Rex wrote:
>See this in detail at WSC online store
>http://store.williamssoaring.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=WSP&Product_Code=06JJTIEDOWN&Category_Code=SP
>
>Great device produced by JJ.
>
>Regards,
>Rex Mayes
>Williams Soaring Center
>

or make it yourself for 20 bucks

[JJ Sinclair]

Pete Smith wrote>>>>>>>
> or make it yourself for 20 bucks

Yep, the materials did cost about $20 bucks, 2024-T3 (.062) + 2 hinges
& 2 cargo tie-downs and don't forget the padding and contact cement,
now find someone with a sheet metal shears and brake. Then cut, bend,
trim, rivet, glue, box and ship.....................man are we making
a killing on this?

I have used these for years and some local pilots finally got me to
make up a run, with travel time down to use the shears I have a good
15 hours into making 8 sets for a whopping $42 bucks an hour + gas (my
shop rate is $65/hr)................won't make that mistake again!
JJ

[bumper]

JJ,

I have a good
> 15 hours into making 8 sets for a whopping $42 bucks an hour + gas (my
> shop rate is $65/hr)................won't make that mistake again!
> JJ
>


JJ,

You have infringed on the business model I have in place for the Quiet Vent
(sells for $6) and the MKII yaw string - $10. Since you did not contact me
seeking permission to license my copyrighted business model, you will either
have to raise your prices immediately or suffer the wrath of my team of
attorneys.

BTW, I also have patent pending on "Buy High Sell Low" and "Dare to be
different . . . circle in sink."

You have been warned!

bumper

[Uncle Fuzzy]

On Aug 4, 7:58*am, "bumper" > wrote:
> JJ,
>
> I have a good
>
> > 15 hours into making 8 sets for a whopping $42 bucks an hour + gas (my
> > shop rate is $65/hr)................won't make that mistake again!
> > JJ
>
> JJ,
>
> You have infringed on the business model I have in place for the Quiet Vent
> (sells for $6) and the MKII yaw string - $10. Since you did not contact me
> seeking permission to license my copyrighted business model, you will either
> have to raise your prices immediately or suffer the wrath of my team of
> attorneys.
>
> BTW, I also have patent pending on "Buy High Sell Low" and "Dare to be
> different . . . circle in sink."
>
> You have been warned!
>
> bumper

JJ,
I wouldn't worry too much about Bumper's threats of legal action.
He also claims to have patent rights for the "Mark II Thermal
Dissaptor" and the "Mark 1 Cumulus Destroyer" which I have been
developing independently for some time. He hasn't gone through with
his threats yet, but maybe he's taking it easy on me because I
purchased a QV and MKII yaw string from him. ;-P
My non-patented Mk II yaw string monitor is still under development,
but shows promise.
Uncle "Flies with Sheep" Fuzzy

[[email protected]]

So who is this "Pete Smith"? Just want ya'll to know it ain't me. My
dog's not in this hunt.

[raulb]

On Aug 3, 1:42*pm, JJ Sinclair > wrote:
> Padded aluminum cusp that slips over trailing edge with web strap that
> goes over leading edge then down to cable or stake with hooks and
> ratchet for tightning. Can be easily carried in ship. E-mail me for
> picture.........see Williams Soaring, set of two for $125 + shipping.
> JJ

I bought 2 back belts with velcro closing (but without the shoulder
straps) and a couple of textile motorcycle tiedown loops (not the
ratchet straps, but what you put on the bike to protect it from the
metal hooks) and had 2 excellent tiedown cuffs for less than $25
lot. For the nervous, they can be stitched.

[JJ Sinclair]

On Aug 5, 7:29*pm, raulb > wrote:

> I bought 2 back belts with velcro closing (but without the shoulder
> straps) and a couple of textile motorcycle tiedown loops (not the
> ratchet straps, but what you put on the bike to protect it from the
> metal hooks) and had *2 excellent tiedown cuffs for less than $25
> lot. *For the nervous, they can be stitched.


In the 35 years I have been in this sport I have seen 3 ships upside
down on the ramp................so when I leave the ship tied out I
make sure its adequately secured. The trailing edge cusp distributes
the load and prevents cauging flaps or ailerons. The force is all
forward and then down over the leading edge and ratchet'd down against
wing stands. I also chock both wheels.
JJ

[raulb]

I am sorry JJ. I mis-read the posts. I didn't realize you were
selling these things until after I posted. I thought I was thumbing
my nose at someone else.

[Ramy]

On Aug 6, 10:25*am, raulb > wrote:
> I am sorryJJ. *I mis-read the posts. *I didn't realize you were
> selling these things until after I posted. *I thought I was thumbing
> my nose at someone else.

I've been using JJ's tie-down kit with my ASW27 successfully. The
ASW27 does not have otherwise any acceptable method for tie down which
I know off. JJ's tie downs can go over the aileron or flaps without
damaging them since the force is mostly all forward. I use them over
the aileron/flap juncture. They are small enough to be carried easily
in most gliders. I also carry JJ's wing tip detachable wheel, another
great JJ product, for aeroretrieves from dirt strips without wing
runner. Both kits can be carried easily in my 27 compartment.
I recently landed at Minden and used the tie downs without wing
stands. The wind was calm when I landed but started blowing at dawn
and was gusting over 30 when I arrived at the airport. It even blew
the wind sock away, but the tie downs held nicely with no harm to the
wings. JJ's tie down kit passed the test :-)

Both products are available from Williams Soaring Center:
http://store.williamssoaring.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=WSP&Product_Code=06JJTIEDOWN&Category_Code=SP

Ramy

[[email protected]]

On Sep 12, 2:13*pm, Ramy > wrote:
> On Aug 6, 10:25*am, raulb > wrote:
>
> > I am sorryJJ. *I mis-read the posts. *I didn't realize you were
> > selling these things until after I posted. *I thought I was thumbing
> > my nose at someone else.
>
> I've been using JJ's tie-down kit with my ASW27 successfully. The
> ASW27 does not have otherwise any acceptable method for tie down which
> I know off. JJ's tie downs can go over the aileron or flaps without
> damaging them since the force is mostly all forward.
>
> Ramy

I thread nylon webbing around the divebrake pivot on the -27 (the
steel tube that runs between the foreward and aft walls of the box
about 1.5 inches down inside the divebrake box itself - not the tube
that sticks up and holds the panels) then back down over the leading
edge of the wing to whatever I'm tying to - no fabrication required.
The same principle applies as for JJ's rig only more so since the
webbing comes straight up out of the box, makes a 90-degree turn to
follow the top surface of the wing to the leading edge and then
straight down to the ground. The force on the divebrake pivot would be
straight up if the tiedown comes under tension, but I think most of
the force would be tranmitted to the top surface of the wing from
surface fricton leaving the residual loads on the pivot relatively
low. I also put wingstands under both wings so I am not sinching the
dihedral out of my wings.

I'm told the factory doesn't recommend tying to the divebrakes, but I
suspect they were thinking about wrapping rope around the tubes that
stick up when the brakes are deployed - pulling on those would put a
lot of torque on the pivot.

JJ's design looks good (thanks JJ!) as long as they are ensured of
pulling the trailing edge forward along the chord - on a control
surface I'd worry that it might deflect upward
under tension and hurt something.

9B

[JJ Sinclair]

The ideal location for the trailing edge cuff is over the trailing
edge of the wing at a location where no control surface is located, as
in a standard class ship. On a 15 meter bird like the 27, the whole
trailing edge is either flap or aileron. I have used the trailing edge
cuff where the flap and aileron meet for years on my Nimbus-3 and LS-6
without causing any control surface damage. Any slight upward pressure
is restrained in the flap and aileron push-rods which are loaded in
tension as upward forces are trying to raise both control surfaces
together.

I would however, reconsider pulling upward on the spoiler push-rod
which is quite strong in tension, but quite weak when bending loads
are applied.
JJ

> I'm told the factory doesn't recommend tying to the divebrakes, but I
> suspect they were thinking about wrapping rope around the tubes that
> stick up when the brakes are deployed - pulling on those would put a
> lot of torque on the pivot.
>
> JJ's design looks good (thanks JJ!) as long as they are ensured of
> pulling the trailing edge forward along the chord - on a control
> surface I'd worry that it might deflect upward
> under tension and hurt something.
>
> 9B

[[email protected]]

On Sep 14, 8:05*am, JJ Sinclair > wrote:
> The ideal location for the trailing edge cuff is over the trailing
> edge of the wing at a location where no control surface is located, as
> in a standard class ship. On a 15 meter bird like the 27, the whole
> trailing edge is either flap or aileron. I have used the trailing edge
> cuff where the flap and aileron meet for years on my Nimbus-3 and LS-6
> without causing any control surface damage. Any slight upward pressure
> is restrained in the flap and aileron push-rods which are loaded in
> tension as upward forces are trying to raise both control surfaces
> together.
>
> *I would however, reconsider pulling upward on the spoiler push-rod
> which is quite strong in tension, but quite weak when bending loads
> are applied.
> JJ

Hey JJ,

I don't tie to the pushrod. I agree, it is is too long and not likely
stong in bending load. Instead I thread the webbing around the 1.5-
inch long T that is the bottom of the whole pivot for the divebrake.
There is one inboard and one outboard on each divebrake - I tend to
tie to the outboard one. They are essentially the bottom corners of
the whole parallelogram that allows each divebrake to swing up out of
the box. Since they run chordwise inside the box and are anchored fore
and aft by 3/4" steel bearings set in carbon fiber next to the spar it
would seem to me to be one of the more stout parts on the whole wing
structure - certainly at least as strong as control surface hinges.
But since I have not cut into my wing to see how it's really put
together I can't be absolutely sure which is why I was asking around
from people who maybe have seen inside a -27 wing.

If it's still not totally clear which part I'm talking about I'll take
a picture when I get home. I've never had a problem with doing it this
way. On the other hand, I've never seen any tiedown actually rip off
of the airplane even though I've seen some pretty sketchy methods - so
lack of a catastrophe doesn't prove much.

I guess you can get away with putting the JJ rig at the flap/divebrake
intersection as long as there isn't a lot of play in the control
circuit so everything stays snug and aligned. But here's a thought
experiment - I cup the cuff over the trailing edge and lay the web
across the top surface of the wing, then I squat in front of my glider
and yank on the strap from a low angle as hard as I can to simulate a
big wind gust trying to lift my glider up. Those -27 control surfaces
seem so thin and delicate - it makes me nervous to think about it. But
I don't glue gliders back together for a living so maybe I'm being too
squeamish.

9B

[JJ Sinclair]

On Sep 14, 5:11*pm, wrote:
> On Sep 14, 8:05*am, JJ Sinclair > wrote:
>
> > The ideal location for the trailing edge cuff is over the trailing
> > edge of the wing at a location where no control surface is located, as
> > in a standard class ship. On a 15 meter bird like the 27, the whole
> > trailing edge is either flap or aileron. I have used the trailing edge
> > cuff where the flap and aileron meet for years on my Nimbus-3 and LS-6
> > without causing any control surface damage. Any slight upward pressure
> > is restrained in the flap and aileron push-rods which are loaded in
> > tension as upward forces are trying to raise both control surfaces
> > together.
>
> > *I would however, reconsider pulling upward on the spoiler push-rod
> > which is quite strong in tension, but quite weak when bending loads
> > are applied.
> > JJ
>
> Hey JJ,
>
> I don't tie to the pushrod. I agree, it is is too long and not likely
> stong in bending load. *Instead I thread the webbing around the 1.5-
> inch long T that is the bottom of the whole pivot for the divebrake.
> There is one inboard and one outboard on each divebrake - I tend to
> tie to the outboard one. They are essentially the bottom corners of
> the whole parallelogram that allows each divebrake to swing up out of
> the box. Since they run chordwise inside the box and are anchored fore
> and aft by 3/4" steel bearings set in carbon fiber next to the spar it
> would seem to me to be one of the more stout parts on the whole wing
> structure - certainly at least as strong as control surface hinges.
> But since I have not cut into my wing to see how it's really put
> together I can't be absolutely sure which is why I was asking around
> from people who maybe have seen inside a -27 wing.
>
> If it's still not totally clear which part I'm talking about I'll take
> a picture when I get home. I've never had a problem with doing it this
> way. On the other hand, I've never seen any tiedown actually rip off
> of the airplane even though I've seen some pretty sketchy methods - so
> lack of a catastrophe doesn't prove much.
Schleicher wisely recommends against using the spoilers as a tie-down
location because you are applying high loads to a butt weld which is
weak under side loads. The same loads will be present when using the
short drive arm to attach a web strap, although admittedly not as high
as attaching to the vertical arms. If you bend anthing in there, your
spoilers won't close and lock completery.............guess how I know
this to be true?

The loads applied using the trailing edge cuff are 90% forward and 10%
upward. As demonstrated by 20 years in use, the control hinges are
plenty strong enough to withstand the forward load and the control
mechanism is plenty strong enough to take the 10% upward load. The
cuff is well padded and bent to an angle that grips the sides before
the trailing edge seats fully.

What we're talking about here is the lesser of two evils while still
providing an acceptable solution to tying the ship down when
necessary.
JJ

>
> I guess you can get away with putting the JJ rig at the flap/divebrake
> intersection as long as there isn't a lot of play in the control
> circuit so everything stays snug and aligned. But here's a thought
> experiment - *I cup the cuff over the trailing edge and lay the web
> across the top surface of the wing, then I squat in front of my glider
> and yank on the strap from a low angle as hard as I can to simulate a
> big wind gust trying to lift my glider up. Those -27 control surfaces
> seem so thin and delicate - it makes me nervous to think about it. But
> I don't glue gliders back together for a living so maybe I'm being too
> squeamish.
>
> 9B

[[email protected]]

On Sep 15, 6:15*am, JJ Sinclair > wrote:
> On Sep 14, 5:11*pm, wrote:
>
>
>
> > On Sep 14, 8:05*am, JJ Sinclair > wrote:
>
> > > The ideal location for the trailing edge cuff is over the trailing
> > > edge of the wing at a location where no control surface is located, as
> > > in a standard class ship. On a 15 meter bird like the 27, the whole
> > > trailing edge is either flap or aileron. I have used the trailing edge
> > > cuff where the flap and aileron meet for years on my Nimbus-3 and LS-6
> > > without causing any control surface damage. Any slight upward pressure
> > > is restrained in the flap and aileron push-rods which are loaded in
> > > tension as upward forces are trying to raise both control surfaces
> > > together.
>
> > > *I would however, reconsider pulling upward on the spoiler push-rod
> > > which is quite strong in tension, but quite weak when bending loads
> > > are applied.
> > > JJ
>
> > Hey JJ,
>
> > I don't tie to the pushrod. I agree, it is is too long and not likely
> > stong in bending load. *Instead I thread the webbing around the 1.5-
> > inch long T that is the bottom of the whole pivot for the divebrake.
> > There is one inboard and one outboard on each divebrake - I tend to
> > tie to the outboard one. They are essentially the bottom corners of
> > the whole parallelogram that allows each divebrake to swing up out of
> > the box. Since they run chordwise inside the box and are anchored fore
> > and aft by 3/4" steel bearings set in carbon fiber next to the spar it
> > would seem to me to be one of the more stout parts on the whole wing
> > structure - certainly at least as strong as control surface hinges.
> > But since I have not cut into my wing to see how it's really put
> > together I can't be absolutely sure which is why I was asking around
> > from people who maybe have seen inside a -27 wing.
>
> > If it's still not totally clear which part I'm talking about I'll take
> > a picture when I get home. I've never had a problem with doing it this
> > way. On the other hand, I've never seen any tiedown actually rip off
> > of the airplane even though I've seen some pretty sketchy methods - so
> > lack of a catastrophe doesn't prove much.
>
> Schleicher wisely recommends against using the spoilers as a tie-down
> location because you are applying high loads to a butt weld which is
> weak under side loads. The same loads will be present when using the
> short drive arm to attach a web strap, although admittedly not as high
> as attaching to the vertical arms. If you bend anthing in there, your
> spoilers won't close and lock completery.............guess how I know
> this to be true?
>
> The loads applied using the trailing edge cuff are 90% forward and 10%
> upward. As demonstrated by 20 years in use, the control hinges are
> plenty strong enough to withstand the forward load and the control
> mechanism is plenty strong enough to take the 10% upward load. The
> cuff is well padded and bent to an angle that grips the sides before
> the trailing edge seats fully.
>
> What we're talking about here is the lesser of two evils while still
> providing an acceptable solution to tying the ship down when
> necessary.
> JJ
>
>
>
>
>
> > I guess you can get away with putting the JJ rig at the flap/divebrake
> > intersection as long as there isn't a lot of play in the control
> > circuit so everything stays snug and aligned. But here's a thought
> > experiment - *I cup the cuff over the trailing edge and lay the web
> > across the top surface of the wing, then I squat in front of my glider
> > and yank on the strap from a low angle as hard as I can to simulate a
> > big wind gust trying to lift my glider up. Those -27 control surfaces
> > seem so thin and delicate - it makes me nervous to think about it. But
> > I don't glue gliders back together for a living so maybe I'm being too
> > squeamish.
>
> > 9B- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -

Thanks JJ - I'm going to take another look. I haven't seen a butt weld
in that location, so now I have something to look for.

9B

[JJ Sinclair]

On Sep 16, 5:45*am, wrote:
> On Sep 15, 6:15*am, JJ Sinclair > wrote:
>
>
>
>
>
> > On Sep 14, 5:11*pm, wrote:
>
> > > On Sep 14, 8:05*am, JJ Sinclair > wrote:
>
> > > > The ideal location for the trailing edge cuff is over the trailing
> > > > edge of the wing at a location where no control surface is located, as
> > > > in a standard class ship. On a 15 meter bird like the 27, the whole
> > > > trailing edge is either flap or aileron. I have used the trailing edge
> > > > cuff where the flap and aileron meet for years on my Nimbus-3 and LS-6
> > > > without causing any control surface damage. Any slight upward pressure
> > > > is restrained in the flap and aileron push-rods which are loaded in
> > > > tension as upward forces are trying to raise both control surfaces
> > > > together.
>
> > > > *I would however, reconsider pulling upward on the spoiler push-rod
> > > > which is quite strong in tension, but quite weak when bending loads
> > > > are applied.
> > > > JJ
>
> > > Hey JJ,
>
> > > I don't tie to the pushrod. I agree, it is is too long and not likely
> > > stong in bending load. *Instead I thread the webbing around the 1.5-
> > > inch long T that is the bottom of the whole pivot for the divebrake.
> > > There is one inboard and one outboard on each divebrake - I tend to
> > > tie to the outboard one. They are essentially the bottom corners of
> > > the whole parallelogram that allows each divebrake to swing up out of
> > > the box. Since they run chordwise inside the box and are anchored fore
> > > and aft by 3/4" steel bearings set in carbon fiber next to the spar it
> > > would seem to me to be one of the more stout parts on the whole wing
> > > structure - certainly at least as strong as control surface hinges.
> > > But since I have not cut into my wing to see how it's really put
> > > together I can't be absolutely sure which is why I was asking around
> > > from people who maybe have seen inside a -27 wing.
>
> > > If it's still not totally clear which part I'm talking about I'll take
> > > a picture when I get home. I've never had a problem with doing it this
> > > way. On the other hand, I've never seen any tiedown actually rip off
> > > of the airplane even though I've seen some pretty sketchy methods - so
> > > lack of a catastrophe doesn't prove much.
>
> > Schleicher wisely recommends against using the spoilers as a tie-down
> > location because you are applying high loads to a butt weld which is
> > weak under side loads. The same loads will be present when using the
> > short drive arm to attach a web strap, although admittedly not as high
> > as attaching to the vertical arms. If you bend anthing in there, your
> > spoilers won't close and lock completery.............guess how I know
> > this to be true?
>
> > The loads applied using the trailing edge cuff are 90% forward and 10%
> > upward. As demonstrated by 20 years in use, the control hinges are
> > plenty strong enough to withstand the forward load and the control
> > mechanism is plenty strong enough to take the 10% upward load. The
> > cuff is well padded and bent to an angle that grips the sides before
> > the trailing edge seats fully.
>
> > What we're talking about here is the lesser of two evils while still
> > providing an acceptable solution to tying the ship down when
> > necessary.
> > JJ
>
> > > I guess you can get away with putting the JJ rig at the flap/divebrake
> > > intersection as long as there isn't a lot of play in the control
> > > circuit so everything stays snug and aligned. But here's a thought
> > > experiment - *I cup the cuff over the trailing edge and lay the web
> > > across the top surface of the wing, then I squat in front of my glider
> > > and yank on the strap from a low angle as hard as I can to simulate a
> > > big wind gust trying to lift my glider up. Those -27 control surfaces
> > > seem so thin and delicate - it makes me nervous to think about it. But
> > > I don't glue gliders back together for a living so maybe I'm being too
> > > squeamish.
>
> > > 9B- Hide quoted text -
>
> > - Show quoted text -- Hide quoted text -
>
> > - Show quoted text -
>
> Thanks JJ - I'm going to take another look. I haven't seen a butt weld
> in that location, so now I have something to look for.
>
> 9B- Hide quoted text -
>
> - Show quoted text -

Andy,
I just took a look at an ASW-20 wing in my barn and although I don't
recommend it, it looks as though a web-strap that was shoved
completely under the outboard divebrake pivot bolt (sleeve), would
pass the tie-down loads into 2 vertical plywood blocks and then into
the upper spar cap and might be a satisfactory place to attach your
tie-down strap.
JJ
PS, I have a repaired 20A fuselage, both wings and a broken stab that
could be the makings of a nice re-build project for 4K, no trailer, no
instruments.

[5Z]

On Sep 16, 9:52*am, JJ Sinclair > wrote:
> On Sep 16, 5:45*am, wrote:
>
>
>
> > On Sep 15, 6:15*am, JJ Sinclair > wrote:
>
> > > On Sep 14, 5:11*pm, wrote:
>
> > > > On Sep 14, 8:05*am, JJ Sinclair > wrote:
>
> > > > > The ideal location for the trailing edge cuff is over the trailing
> > > > > edge of the wing at a location where no control surface is located, as
> > > > > in a standard class ship. On a 15 meter bird like the 27, the whole
> > > > > trailing edge is either flap or aileron. I have used the trailing edge
> > > > > cuff where the flap and aileron meet for years on my Nimbus-3 and LS-6
> > > > > without causing any control surface damage. Any slight upward pressure
> > > > > is restrained in the flap and aileron push-rods which are loaded in
> > > > > tension as upward forces are trying to raise both control surfaces
> > > > > together.
>
> > > > > *I would however, reconsider pulling upward on the spoiler push-rod
> > > > > which is quite strong in tension, but quite weak when bending loads
> > > > > are applied.
> > > > > JJ
>
> > > > Hey JJ,
>
> > > > I don't tie to the pushrod. I agree, it is is too long and not likely
> > > > stong in bending load. *Instead I thread the webbing around the 1..5-
> > > > inch long T that is the bottom of the whole pivot for the divebrake..
> > > > There is one inboard and one outboard on each divebrake - I tend to
> > > > tie to the outboard one. They are essentially the bottom corners of
> > > > the whole parallelogram that allows each divebrake to swing up out of
> > > > the box. Since they run chordwise inside the box and are anchored fore
> > > > and aft by 3/4" steel bearings set in carbon fiber next to the spar it
> > > > would seem to me to be one of the more stout parts on the whole wing
> > > > structure - certainly at least as strong as control surface hinges.
> > > > But since I have not cut into my wing to see how it's really put
> > > > together I can't be absolutely sure which is why I was asking around
> > > > from people who maybe have seen inside a -27 wing.
>
> > > > If it's still not totally clear which part I'm talking about I'll take
> > > > a picture when I get home. I've never had a problem with doing it this
> > > > way. On the other hand, I've never seen any tiedown actually rip off
> > > > of the airplane even though I've seen some pretty sketchy methods - so
> > > > lack of a catastrophe doesn't prove much.
>
> > > Schleicher wisely recommends against using the spoilers as a tie-down
> > > location because you are applying high loads to a butt weld which is
> > > weak under side loads. The same loads will be present when using the
> > > short drive arm to attach a web strap, although admittedly not as high
> > > as attaching to the vertical arms. If you bend anthing in there, your
> > > spoilers won't close and lock completery.............guess how I know
> > > this to be true?
>
> > > The loads applied using the trailing edge cuff are 90% forward and 10%
> > > upward. As demonstrated by 20 years in use, the control hinges are
> > > plenty strong enough to withstand the forward load and the control
> > > mechanism is plenty strong enough to take the 10% upward load. The
> > > cuff is well padded and bent to an angle that grips the sides before
> > > the trailing edge seats fully.
>
> > > What we're talking about here is the lesser of two evils while still
> > > providing an acceptable solution to tying the ship down when
> > > necessary.
> > > JJ
>
> > > > I guess you can get away with putting the JJ rig at the flap/divebrake
> > > > intersection as long as there isn't a lot of play in the control
> > > > circuit so everything stays snug and aligned. But here's a thought
> > > > experiment - *I cup the cuff over the trailing edge and lay the web
> > > > across the top surface of the wing, then I squat in front of my glider
> > > > and yank on the strap from a low angle as hard as I can to simulate a
> > > > big wind gust trying to lift my glider up. Those -27 control surfaces
> > > > seem so thin and delicate - it makes me nervous to think about it. But
> > > > I don't glue gliders back together for a living so maybe I'm being too
> > > > squeamish.
>
> > > > 9B- Hide quoted text -
>
> > > - Show quoted text -- Hide quoted text -
>
> > > - Show quoted text -
>
> > Thanks JJ - I'm going to take another look. I haven't seen a butt weld
> > in that location, so now I have something to look for.
>
> > 9B- Hide quoted text -
>
> > - Show quoted text -
>
> Andy,
> I just took a look at an ASW-20 wing in my barn and although I don't
> recommend it, it looks as though a web-strap that was shoved
> completely under the outboard divebrake pivot bolt (sleeve), would
> pass the tie-down loads into 2 vertical plywood blocks and then into
> the upper spar cap and might be a satisfactory place to attach your
> tie-down strap.

I think that's where Andy attaches the strap. That's what I do as
well on my ASH-26E using a 2" wide strap to get as much load
distribution as possible. I run the strap under both spoiler pivot
points then forward and join them near the ground anchor point. That
way, each strap is mostly pulling straight forward.

This is purely for securing the ship either when the trailer is not
available after a remote landing, or for occasional overnight parking
in benign conditions. So I never expect this to be tested to its
limits. But I think it would be better that something got bent than
the ship blowing away if the unexpected did happen.

-Tom

[[email protected]]

On Sep 16, 10:20*am, 5Z > wrote:
> On Sep 16, 9:52*am, JJ Sinclair > wrote:
>
>
>
> > On Sep 16, 5:45*am, wrote:
>
> > > On Sep 15, 6:15*am, JJ Sinclair > wrote:
>
> > > > On Sep 14, 5:11*pm, wrote:
>
> > > > > On Sep 14, 8:05*am, JJ Sinclair > wrote:
>
> > > > > > The ideal location for the trailing edge cuff is over the trailing
> > > > > > edge of the wing at a location where no control surface is located, as
> > > > > > in a standard class ship. On a 15 meter bird like the 27, the whole
> > > > > > trailing edge is either flap or aileron. I have used the trailing edge
> > > > > > cuff where the flap and aileron meet for years on my Nimbus-3 and LS-6
> > > > > > without causing any control surface damage. Any slight upward pressure
> > > > > > is restrained in the flap and aileron push-rods which are loaded in
> > > > > > tension as upward forces are trying to raise both control surfaces
> > > > > > together.
>
> > > > > > *I would however, reconsider pulling upward on the spoiler push-rod
> > > > > > which is quite strong in tension, but quite weak when bending loads
> > > > > > are applied.
> > > > > > JJ
>
> > > > > Hey JJ,
>
> > > > > I don'ttieto the pushrod. I agree, it is is too long and not likely
> > > > > stong in bending load. *Instead I thread the webbing around the 1.5-
> > > > > inch long T that is the bottom of the whole pivot for the divebrake.
> > > > > There is one inboard and one outboard on each divebrake - I tend to
> > > > >tieto the outboard one. They are essentially the bottom corners of
> > > > > the whole parallelogram that allows each divebrake to swing up out of
> > > > > the box. Since they run chordwise inside the box and are anchored fore
> > > > > and aft by 3/4" steel bearings set in carbon fiber next to the spar it
> > > > > would seem to me to be one of the more stout parts on the whole wing
> > > > > structure - certainly at least as strong as control surface hinges.
> > > > > But since I have not cut into my wing to see how it's really put
> > > > > together I can't be absolutely sure which is why I was asking around
> > > > > from people who maybe have seen inside a -27 wing.
>
> > > > > If it's still not totally clear which part I'm talking about I'll take
> > > > > a picture when I get home. I've never had a problem with doing it this
> > > > > way. On the other hand, I've never seen any tiedown actually rip off
> > > > > of the airplane even though I've seen some pretty sketchy methods - so
> > > > > lack of a catastrophe doesn't prove much.
>
> > > > Schleicher wisely recommends against using the spoilers as atie-down
> > > > location because you are applying high loads to a butt weld which is
> > > > weak under side loads. The same loads will be present when using the
> > > > short drive arm to attach a web strap, although admittedly not as high
> > > > as attaching to the vertical arms. If you bend anthing in there, your
> > > > spoilers won't close and lock completery.............guess how I know
> > > > this to be true?
>
> > > > The loads applied using the trailing edge cuff are 90% forward and 10%
> > > > upward. As demonstrated by 20 years in use, the control hinges are
> > > > plenty strong enough to withstand the forward load and the control
> > > > mechanism is plenty strong enough to take the 10% upward load. The
> > > > cuff is well padded and bent to an angle that grips the sides before
> > > > the trailing edge seats fully.
>
> > > > What we're talking about here is the lesser of two evils while still
> > > > providing an acceptable solution to tying the shipdownwhen
> > > > necessary.
> > > > JJ
>
> > > > > I guess you can get away with putting the JJ rig at the flap/divebrake
> > > > > intersection as long as there isn't a lot of play in the control
> > > > > circuit so everything stays snug and aligned. But here's a thought
> > > > > experiment - *I cup the cuff over the trailing edge and lay the web
> > > > > across the top surface of the wing, then I squat in front of my glider
> > > > > and yank on the strap from a low angle as hard as I can to simulate a
> > > > > big wind gust trying to lift my glider up. Those -27 control surfaces
> > > > > seem so thin and delicate - it makes me nervous to think about it.. But
> > > > > I don't glue gliders back together for a living so maybe I'm being too
> > > > > squeamish.
>
> > > > > 9B- Hide quoted text -
>
> > > > - Show quoted text -- Hide quoted text -
>
> > > > - Show quoted text -
>
> > > Thanks JJ - I'm going to take another look. I haven't seen a butt weld
> > > in that location, so now I have something to look for.
>
> > > 9B- Hide quoted text -
>
> > > - Show quoted text -
>
> > Andy,
> > I just took a look at an ASW-20 wing in my barn and although I don't
> > recommend it, it looks as though a web-strap that was shoved
> > completely under the outboard divebrake pivot bolt (sleeve), would
> > pass thetie-downloads into 2 vertical plywood blocks and then into
> > the upper spar cap and might be a satisfactory place to attach your
> >tie-downstrap.
>
> I think that's where Andy attaches the strap. *That's what I do as
> well on my ASH-26E using a 2" wide strap to get as much load
> distribution as possible. *I run the strap under both spoiler pivot
> points then forward and join them near the ground anchor point. *That
> way, each strap is mostly pulling straight forward.
>
> This is purely for securing the ship either when the trailer is not
> available after a remote landing, or for occasional overnight parking
> in benign conditions. *So I never expect this to be tested to its
> limits. *But I think it would be better that something got bent than
> the ship blowing away if the unexpected did happen.
>
> -Tom

Tom and JJ,

That's exactly it. I use the 1" webbing that came with the ship and
only tie down to the outboard pivot. The webbing should be good to 600
lbs. I doubt a piece of steel tubing that short would bend as there is
no moment arm. Worst case is the whole thing rips out. But if the -27
is constructed like the -20 my Engineer's mind tells me the strap
would break before the spar ripped out. It would have to be 2+ Gs of
lift which seems improbable since one advantage of this approach is
that it keeps the dive brakes open.

JJ - thank a lot for looking inside the wing - you are one of the few
guys here in a position to do it. I know I'm on my own responsibility
on this - but I feel a bit better knowing that there is some decent
structure in there.

9B

[Eric Greenwell]

wrote:

>
> JJ - thank a lot for looking inside the wing - you are one of the few
> guys here in a position to do it. I know I'm on my own responsibility
> on this - but I feel a bit better knowing that there is some decent
> structure in there.

Since the spoilers have to survive opening at Vne, I imagine there is
*very* decent structure in there.

I prefer to use a strap that engages both pivots in the spoiler box,
because it spreads the load to each pivot, and has twice as many straps
to spread the load pressing on the wing surface.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

[[email protected]]

On Sep 18, 6:44*pm, Eric Greenwell > wrote:
> wrote:
>
> > JJ - thank a lot for looking inside the wing - you are one of the few
> > guys here in a position to do it. I know I'm on my own responsibility
> > on this - but I feel a bit better knowing that there is some decent
> > structure in there.
>
> Since the spoilers have to survive opening at Vne, I imagine there is
> *very* decent structure in there.
>
> I prefer to use a strap that engages both pivots in the spoiler box,
> because it spreads the load to each pivot, and has twice as many straps
> to spread the load pressing on the wing surface.
>
> --
> Eric Greenwell - Washington State, USA
> * Change "netto" to "net" to email me directly
>
> * Updated! "Transponders in Sailplanes"http://tinyurl.com/y739x4
> * * * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more
>
> * "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Makes sense Eric. Although the air loads at Vne exert slightly
different forces and moments than the tiedown strap - it is still a
lot of tugging and twisting on the pivots. In a 90-degree dive at
terminal velocity the drag equals the weight. I presume a whole lot of
that drag comes from the flat plate drag of the divebrakes. If you
also consider that you have to be able to open the divebrakes at Vne,
that's a pretty big impulse load.

I have some other practical considerations for tying to one pivot -
but I'm not too worried now.

9B

[[email protected]]

On Sep 18, 8:52*pm, wrote:
> On Sep 18, 6:44*pm, Eric Greenwell > wrote:
>
>
>
> > wrote:
>
> > > JJ - thank a lot for looking inside the wing - you are one of the few
> > > guys here in a position to do it. I know I'm on my own responsibility
> > > on this - but I feel a bit better knowing that there is some decent
> > > structure in there.
>
> > Since the spoilers have to survive opening at Vne, I imagine there is
> > *very* decent structure in there.
>
> > I prefer to use a strap that engages both pivots in the spoiler box,
> > because it spreads the load to each pivot, and has twice as many straps
> > to spread the load pressing on the wing surface.
>
> > --
> > Eric Greenwell - Washington State, USA
> > * Change "netto" to "net" to email me directly
>
> > * Updated! "Transponders in Sailplanes"http://tinyurl.com/y739x4
> > * * * New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more
>
> > * "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org
>
> Makes sense Eric. Although the air loads at Vne exert slightly
> different forces and moments than the tiedown strap - it is still a
> lot of tugging and twisting on the pivots. In a 90-degree dive at
> terminal velocity the drag equals the weight. I presume a whole lot of
> that drag comes from the flat plate drag of the divebrakes. If you
> also consider that you have to be able to open the divebrakes at Vne,
> that's a pretty big impulse load.
>
> I have some other practical considerations for tying to one pivot -
> but I'm not too worried now.
>
> 9B

On further reflection, if you think about the forces involved and how
the divebrake mechanism is constructed, I think each of those pivots
has to be built to take several thousand pounds in shear. That's
because the divebrake is cantilevered on about a 10-12" arm down to a
1" tee that is anchored to the walls of the divebrake box. If the drag
on the divebrake is on a 10-12" moment arm down to a 1" perpendicular
T then 1,000 lbs of drag turns into something like 2,500 lbs of shear
per pivot (1,250 upward at the front mount and 1,250 downward at the
aft mount for each of the four pivots - the force is multiplied 10/1
by the lever of the vertical brake arms themselves). This basically
says that in a tiedown application even the strongest webbing will
snap before the divebake pivots pull out.

I'm not 100% sure on the math - but the basic logic feels right.

9B