Shoulder strap discussion

On Jun 8, 8:27*am, Uncle Fuzzy wrote:
On Jun 8, 6:36*am, bildan wrote:



A couple of years ago I got hammered in a wave rotor while flying a
G102. *No matter how tight the shoulder straps, my head kept banging
into the canopy. *This is a big enough problem that some glider owners
are re-locating the shoulder strap anchors lower. I think modifying
the seat belt/shoulder harness is a primary structure issue requiring
337 field modification paperwork in most countries. *There's got to be
a better way.

This issue came up again recently which led me to some "out-of-the-
box" thinking which is the reason for this thread.

What if one had inverted "U" shaped, detachable shoulder pad(s) that
snapped or Velcro'd to the shoulder straps or maybe the parachute
harness? *They would come in various sizes to fit different pilots.
In effect, these would raise the pilots shoulders with pads instead of
lowering the strap attachment points. * The pads would press down on
the pilots shoulders as the straps were tightened preventing canopy
head banging. *These pads would be 'personal gear' and not require a
337.

Do these things already exist? *Discussion?

I have the same issue with my Speed Astir. *No matter how tight the
lap and shoulder belts are, my head bashes the canopy with every
strong bump. *In 2006, I bashed the canpy OFF the glider. *That was
exciting. *I've also considered rigid foam pads atop my shoulders. *If
you try it, please post up how well it works.
Thanks

If you make them tall enough they'll touch the canopy before your head
does.

Even shorter ones might restrict your ability to look left and right
by the time you get them tall enough to meaningfully change the strap
angle. I would think given the forces involved there'd be some risk
that they'd rotate out of position or flop over sideways - depending
on how tall they need to be - or the u-pad would need to have a
skeleton of some kind that is quite stiff. Also, having the seatback
adjusted aft helps the angle of the straps on many ships - just
remember to adjust the rudder pedals back too.

I try to strap in with my head low enough that the lap belt is
sufficient to keep me clear - taller pilots in shorter gliders don't
have the same option.

9B

On Jun 8, 11:32*am, Andy wrote:
On Jun 8, 8:27*am, Uncle Fuzzy wrote:



On Jun 8, 6:36*am, bildan wrote:

A couple of years ago I got hammered in a wave rotor while flying a
G102. *No matter how tight the shoulder straps, my head kept banging
into the canopy. *This is a big enough problem that some glider owners
are re-locating the shoulder strap anchors lower. I think modifying
the seat belt/shoulder harness is a primary structure issue requiring
337 field modification paperwork in most countries. *There's got to be
a better way.

This issue came up again recently which led me to some "out-of-the-
box" thinking which is the reason for this thread.

What if one had inverted "U" shaped, detachable shoulder pad(s) that
snapped or Velcro'd to the shoulder straps or maybe the parachute
harness? *They would come in various sizes to fit different pilots.
In effect, these would raise the pilots shoulders with pads instead of
lowering the strap attachment points. * The pads would press down on
the pilots shoulders as the straps were tightened preventing canopy
head banging. *These pads would be 'personal gear' and not require a
337.

Do these things already exist? *Discussion?

I have the same issue with my Speed Astir. *No matter how tight the
lap and shoulder belts are, my head bashes the canopy with every
strong bump. *In 2006, I bashed the canpy OFF the glider. *That was
exciting. *I've also considered rigid foam pads atop my shoulders. *If
you try it, please post up how well it works.
Thanks

If you make them tall enough they'll touch the canopy before your head
does.

Even shorter ones might restrict your ability to look left and right
by the time you get them tall enough to meaningfully change the strap
angle. I would think given the forces involved there'd be some risk
that they'd rotate out of position or flop over sideways - depending
on how tall they need to be - or the u-pad would need to have a
skeleton of some kind that is quite stiff. Also, having the seatback
adjusted aft helps the angle of the straps on many ships - *just
remember to adjust the rudder pedals back too.

I try to strap in with my head low enough that the lap belt is
sufficient to keep me clear - taller pilots in shorter gliders don't
have the same option.

9B

I think they only have to be higher than the strap attach points to
produce considerable downforce.

On Jun 8, 9:36*am, bildan wrote:
A couple of years ago I got hammered in a wave rotor while flying a
G102. *No matter how tight the shoulder straps, my head kept banging
into the canopy. *This is a big enough problem that some glider owners
are re-locating the shoulder strap anchors lower. I think modifying
the seat belt/shoulder harness is a primary structure issue requiring
337 field modification paperwork in most countries. *There's got to be
a better way.

This issue came up again recently which led me to some "out-of-the-
box" thinking which is the reason for this thread.

What if one had inverted "U" shaped, detachable shoulder pad(s) that
snapped or Velcro'd to the shoulder straps or maybe the parachute
harness? *They would come in various sizes to fit different pilots.
In effect, these would raise the pilots shoulders with pads instead of
lowering the strap attachment points. * The pads would press down on
the pilots shoulders as the straps were tightened preventing canopy
head banging. *These pads would be 'personal gear' and not require a
337.

Do these things already exist? *Discussion?

As others have pointed out, there's a whole body of research on pilot/
driver restraint systems. The shoulder straps are clearly intended
to handle longitudinal loads (deceleration), NOT vertical. I can't
lay my hands on it right now, but somewhere or another I found
research indicating the risk of severe spinal damage with excess
downforce provided through the shoulders.

The only right way to accomplish what you want is to focus on the lap
belts or crotch straps. There are dozens of threads on this topic
over the last 10 years. One for example:

http://groups.google.com/group/rec.a...e611e1a0d817a9

FWIW, I have used both 5 and 6 (and, I guess 7) point harnesses in my
gliders for the last 15 years. Since we do extensive ridge running, I
can say that I "wouldn't fly without it" (5 or 6 point harness).

Cheers,
P3

On Jun 8, 1:03*pm, bildan wrote:
Keep in mind that cockpit/belt 'fit' differs widely with pilot
physique. *4-point belts which works great for one pilot may be
problematic for another. *5/6 point belts work great for me and I like
them. *Unfortunately, they aren't fitted (or available) for all
gliders. *Even if they are available, it would involve a form 337 to
install them. *There are really no absolutes.

The shoulder pad idea is just to gain yet another option for smaller
pilots.

I took a look at my parachute and it already has thin shoulder pads on
the harness. *Unfortunately, they are rounded on top which makes the
shoulder belts tend to slide off. *I think I'll ask my rigger if
something could be done about that.

Running a crotch strap from the lap belt attachment points works very
well for me in a G102. No modifications to the structure was
required. Just added some webbing. I didn't even have to do any
permanant modifications to the lap belts. This might work for other
gliders, i don't know.

Todd
3S

On Jun 8, 1:32*pm, Andy wrote:

I try to strap in with my head low enough that the lap belt is
sufficient to keep me clear - taller pilots in shorter gliders don't
have the same option.

9B

This is my basic problem. I only have about 1 inch of clearance
between my head and the canopy. I can only get enough shoulder strap
tension with a crotch strap of some kind.

Todd
3S

On Jun 8, 11:28*am, bildan wrote:
On Jun 8, 11:32*am, Andy wrote:



On Jun 8, 8:27*am, Uncle Fuzzy wrote:

On Jun 8, 6:36*am, bildan wrote:

A couple of years ago I got hammered in a wave rotor while flying a
G102. *No matter how tight the shoulder straps, my head kept banging
into the canopy. *This is a big enough problem that some glider owners
are re-locating the shoulder strap anchors lower. I think modifying
the seat belt/shoulder harness is a primary structure issue requiring
337 field modification paperwork in most countries. *There's got to be
a better way.

This issue came up again recently which led me to some "out-of-the-
box" thinking which is the reason for this thread.

What if one had inverted "U" shaped, detachable shoulder pad(s) that
snapped or Velcro'd to the shoulder straps or maybe the parachute
harness? *They would come in various sizes to fit different pilots.
In effect, these would raise the pilots shoulders with pads instead of
lowering the strap attachment points. * The pads would press down on
the pilots shoulders as the straps were tightened preventing canopy
head banging. *These pads would be 'personal gear' and not require a
337.

Do these things already exist? *Discussion?

I have the same issue with my Speed Astir. *No matter how tight the
lap and shoulder belts are, my head bashes the canopy with every
strong bump. *In 2006, I bashed the canpy OFF the glider. *That was
exciting. *I've also considered rigid foam pads atop my shoulders. *If
you try it, please post up how well it works.
Thanks

If you make them tall enough they'll touch the canopy before your head
does.

Even shorter ones might restrict your ability to look left and right
by the time you get them tall enough to meaningfully change the strap
angle. I would think given the forces involved there'd be some risk
that they'd rotate out of position or flop over sideways - depending
on how tall they need to be - or the u-pad would need to have a
skeleton of some kind that is quite stiff. Also, having the seatback
adjusted aft helps the angle of the straps on many ships - *just
remember to adjust the rudder pedals back too.

I try to strap in with my head low enough that the lap belt is
sufficient to keep me clear - taller pilots in shorter gliders don't
have the same option.

9B

I think they only have to be higher than the strap attach points to
produce considerable downforce.

If some is good, more is better. Simple geometry would tell me the
effectiveness of shoulder straps in restraining your vertical motion
is not linear with the angle of the straps. A fraction of a degree off
horizontal won't help much at all given even a small amount of stretch
in the webbing, slop in the harness and the limits of being able to
cinch the whole thing down. I expect you'd need a decent angle to make
a difference. My shoulder straps sit slightly below shoulder height -
and about 4-5 inches behind the seat back. My experience is that
cinching them down tighter mostly plasters me more tightly against the
seat back, but doesn't help on the vertical axis nearly as much. Of
course that's what they are designed to do.

9B

I have been fooling around with helper belts for a couple of
seasons ...

The following scheme works pretty well ... I tested at the recent
Region 2 contest ...

My wife sewed a couple of loops in 2 " webbing ... the loops are
slipped over the shoulder at the buckle ... the free end passes
through a 2" D-Ring which is secured at at the lap belt attachment
point ... i.e. you remove the lap belt and then re-attach with the D-
Ring included in the loop that circles the the side attachment 'bar'.

The free end of the helper webbing then pass up into the same spring
loaded buckle holding the shoulder straps ... and yep, this works
fine ... no slipping on either belt ... and both are easy to
adjust ...

While this worked ok, finding the D-ring next to your thigh while you
were sitting in the ship was a pain ... so the next approach simply
attached the D-Ring to the free end of the lap belt using a 2"
slider ...

I don't have a photo, but this worked great ... as you bounced on the
ridge, the tension on the shoulder straps kept the laps pulled
tight ... the hold down pressure is quite good and I actually had to
loosen the rig from the pre-takeoff tension as I had it cinched down
tight anticipating it would loosen up ... it never did.

So, is it as good as a five-point ... well, you do have two extra
belts to mess with ... and the 5-belt system is rock solid ... but it
is darn close ... plus it is portable/reversible ... and there is no
restricting already limited crotch real estate.

BTW, when you release the buckle ... the loops pull through the D-
rings ... so you can get out gracefully ... or jump ...

I have a bunch of extra 2" webbing (maroon and blue), D-rings and
sliders ... you can have these for cost + postage (~$10) .... the
webbing has to have the loops sewn ... i.e. I'm not sure I could
impose on my wife ...

Also, looking at other options, I think you could probably just loop
the belts through your crotch and then up to the shoulder buckle to
create an anti-submarine system ... I have not really explored this as
I was just looking for additional hold-down force ... KK

http://sailplane-racing.org/Belts/KKRidgeRope.jpg

I like this version. Mine is essentially the same thing, but run
under the legs for a pair of crotch straps. I am going to try your
version and see how it compares.

Todd
3S

On Jun 8, 10:29*pm, KiloKilo wrote:

Also, looking at other options, I think you could probably just loop
the belts through your crotch and then up to the shoulder buckle to
create an anti-submarine system ... I have not really explored this as
I was just looking for additional hold-down force ... *KK

http://sailplane-racing.org/Belts/KKRidgeRope.jpg

On Jun 9, 7:58*am, wrote:
I like this version. *Mine is essentially the same thing, but run
under the legs for a pair of crotch straps. *I am going to try your
version and see how it compares.

Todd
3S

On Jun 8, 10:29*pm, KiloKilo wrote:

Also, looking at other options, I think you could probably just loop
the belts through your crotch and then up to the shoulder buckle to
create an anti-submarine system ... I have not really explored this as
I was just looking for additional hold-down force ... *KK

http://sailplane-racing.org/Belts/KKRidgeRope.jpg

Todd,

yeah, I think a bunch of us have been trying similar solutions for
this over the years ... I think QV (Richard Kellerman) mentioned that
Eric Mann showed up at a R2 contest one year .... and was wearing
enough carabiners and straps to make a Sherpa jealous ... ;-)

The 2" d-ring seems to work well ... we found it just had to be out
in the open if you want the belt loop to slip through easily ...

And as mentioned (and not pictured) .... hooking the d-ring to to the
free end of the lap belt strap did just that ... plus it kept the
tension on the lap belts ... very tight ...

KK