Crouch Strap story

John Galloway wrote:

Further to my posting yesterday I have identified the
6 point harness in our Std Cirrus as as Luke PRO6F
designed for single seat race cars.

See:

http://www.lukeracing.co.uk/rec.php?cat=17

Flying with it today was the most comfortable I have
ever been in a glider as I felt totally secured with
the lap strap held low and no tendency to slide forward
in the seat pan with the lap strap rising as happens
in so many gliders. Even a deep seat pan like the
front seat of a Duo comes nowhere near in terms to
achieving that feeling.

It may be non approved but I really don't care as the
benefits for comfort and safety are so clear cut.

John Galloway


Could you double check and repost the URL. I am getting a blank page
when I try to load the page.

Thank-you.

At 18:12 07 June 2004, Jc Cunningham wrote:
John Galloway wrote:

Further to my posting yesterday I have identified the
6 point harness in our Std Cirrus as as Luke PRO6F
designed for single seat race cars.

See:

http://www.lukeracing.co.uk/rec.php?cat=17

Flying with it today was the most comfortable I have
ever been in a glider as I felt totally secured with
the lap strap held low and no tendency to slide forward
in the seat pan with the lap strap rising as happens
in so many gliders. Even a deep seat pan like the
front seat of a Duo comes nowhere near in terms to
achieving that feeling.

It may be non approved but I really don't care as the
benefits for comfort and safety are so clear cut.

John Galloway


Could you double check and repost the URL. I am getting
a blank page
when I try to load the page.

Thank-you.

Thats odd because when I click on the link in your
reply I go straight to it. If all else fails go to
www.lukeracing.co.uk main site and click on the main
link for 'race and rally safety harnesses' and then
on 'Recommended' it will take to the page with a list
of their harnesses. At the bottom is the link for
PRO6F which looks identical to what is in our Std Cirrus
except that instead of the bolt clips at the aircraft
attachment end of the lap and shoulder straps we have
normal glider buckles. Also the attachment points
of the 2 thigh straps under our seat pan is a flat
hook/clip instead of the bolt clip. Our central quick
release buckle also looks to be an older less sleek
model (our straps must be 12 years old but hardly used).
Otherwise the picture gives a good idea of how the
straps work - except that in practice the upper ends
of the thigh loops pull at the lowest point of the
shoulder straps and not a few inches higher as shown
in the non-tensioned photographs.

BTW it would be more difficult to attach the straps
to a glider in which the lap straps attach to the seat
pan rather than - as in the Std Cirrus - to a fuselage
mounted metal point with a hole in the seat pan. This
allows access to the mounting point for the lap straps
from above the seat pan and for the thigh straps from
beneath the seat pan. In other gliders I would envisage
extra mounting points being required forward on the
seat pan - perhaps bonded to the bottom of the seat
pan under the upper thighs.

John Galloway

There are quite a few 6 point harness suppliers in the UK. Just google '6
point harness'

Best price I found on the Luke 6 point PRO6F was £103 including VAT and
shipping from www.rallynuts.com

Ian

John Galloway wrote:

At 18:12 07 June 2004, Jc Cunningham wrote:
John Galloway wrote:

Further to my posting yesterday I have identified the
6 point harness in our Std Cirrus as as Luke PRO6F
designed for single seat race cars.

See:

http://www.lukeracing.co.uk/rec.php?cat=17

Flying with it today was the most comfortable I have
ever been in a glider as I felt totally secured with
the lap strap held low and no tendency to slide forward
in the seat pan with the lap strap rising as happens
in so many gliders. Even a deep seat pan like the
front seat of a Duo comes nowhere near in terms to
achieving that feeling.

It may be non approved but I really don't care as the
benefits for comfort and safety are so clear cut.

John Galloway


Could you double check and repost the URL. I am getting
a blank page
when I try to load the page.

Thank-you.

Thats odd because when I click on the link in your
reply I go straight to it. If all else fails go to
www.lukeracing.co.uk main site and click on the main
link for 'race and rally safety harnesses' and then
on 'Recommended' it will take to the page with a list
of their harnesses. At the bottom is the link for
PRO6F which looks identical to what is in our Std Cirrus
except that instead of the bolt clips at the aircraft
attachment end of the lap and shoulder straps we have
normal glider buckles. Also the attachment points
of the 2 thigh straps under our seat pan is a flat
hook/clip instead of the bolt clip. Our central quick
release buckle also looks to be an older less sleek
model (our straps must be 12 years old but hardly used).
Otherwise the picture gives a good idea of how the
straps work - except that in practice the upper ends
of the thigh loops pull at the lowest point of the
shoulder straps and not a few inches higher as shown
in the non-tensioned photographs.

BTW it would be more difficult to attach the straps
to a glider in which the lap straps attach to the seat
pan rather than - as in the Std Cirrus - to a fuselage
mounted metal point with a hole in the seat pan. This
allows access to the mounting point for the lap straps
from above the seat pan and for the thigh straps from
beneath the seat pan. In other gliders I would envisage
extra mounting points being required forward on the
seat pan - perhaps bonded to the bottom of the seat
pan under the upper thighs.

John Galloway



It must have been my browser that was having a problem. I use Opera.
When I used internet explorer it came up fine.

"Ed Byars" wrote a good piece on belting yourself in.

Before you just go and install marginal belts, look at what is available in
the sports car world
and choose the correct parts. Crotch belts or "5 point harnesses"
were developed for upright seated positions. They worked by holding the lap
belt
in the proper position over the hips and weren't designed to take impact
loads
without "stuffing your balls through your throat". As cars became faster
and aero considerations
moved drivers to the supine driving positions used today, "6 point systems"
evolved.
The load path in grontal impacts could no longer be absorbed by the lap
and shoulder belts because the vectors were wrong. What has evolved is a
belting method
that creates a web seat secured to the lap belt attach points. This
prevents the driver from
sliding forward out from under the belting system.

My SCHROTH harness hooks up like this.
Connect lap belt.
left 6 point go's under my leg, around my upper thigh, over to the
left lap belt anchor, thru a loop and back to the buckle.
Same for right side
connect shoulders
done.

What this does is transfer any decelleration loads into the upper
thigh/lower butt
area and is quite comfortable. It virtually eliminates soft tissue bruising
..
I would not fly a 5 point harness as I feel they are unsafe, the risk of
internal injuries to
the soft stuff is too high. BUT the 6 point harness works very very well.
I have
had the unfortunate "experience" of stuffing a formula car and know exactly
what works,
and what doesn't.

I don't have good pictures, but looking at the WILLANS web site gets the
message across.
Look at the way all the sub straps create seats to support you against
sliding forward.


http://www.willansharness.com/

Scott Correa

The 'crotch strap' is what used to be known as a 'negative-G'
strap. Usually it works to keep your skull away from
the canopy during the bumpy bits of sky; rarely, it
helps you in a crash by preventing submarining. However,
a single strap is both inconvenient and potentially
painful. A better design is a double strap, like an
inverted V, but it needs two hard points. Another
variation is an upright V, with one hardpoint and some
secure way to fasten the ends of the V to the lapstraps
rather than the buckle.

The conventional 4-point or 5-point harness shows its
ancestry from the lapstrap by having the primary mounting
[the buckle] on the lapstrap. Would a better design
not have the buckle assembly permanently mounted to
the [adjustable] negative-G strap and the two lap and
two shoulder straps plugging in later ?

Ian




At 15:00 06 June 2004, Bill Daniels wrote:

'Robertmudd1u' wrote in message
...
You may be interested in my latest crotch strap experience.

I'm still analyzing my June 2003 accident and the
cause. More later on
this.
The role of the crotch strap is significant and worthy
of mention.

Dr. Byars, thank you for this interesting and important
feedback based on
real
world experience.

The standard line from the German manufactures is
that a crotch strap is
not
needed because the submarining hazard has been taken
care of through use
of the
'H point' when locating the anchoring point of the
lap belts. This system
locates the lap belt a bit further forward than in
older designs with the
aim
being to get the lap belt lower on your hips. This
is supposed to prevent
it
from being pulled out of place when tightening the
shoulder harness. It
does,
but I believe the lap belt has to be tightened to
an un-necessary degree
to get
anywhere near the effect the 'H point' is credited
with bringing about.

My experience is that the 'H point' is not adequate
to keep the lap belt
from
being pulled up when tightening the shoulder straps.
This is especially
true
when flying out west in strong lift at high speed.
A crotch strap helps
keep
you from bouncing around thus providing more comfort
and better control.
The
difference is security in the cockpit is dramatic.
I normally retro fit a
crotch strap to my gliders and feel a lot safer and
more comfortable with
its
use. This holds true even with my Genesis which used
the 'H point' system
to
locate the lap belt anchor points.

Robert Mudd


After reading Ed and Robert's posts, I intend to install
a crotch strap in
my Nimbus. At the very least, it will let me get the
shoulder straps REALLY
tight without pulling the lap belt up too high.

When you are riding 10 - 15 knot mountain thermals
with a stiff carbon wing
you just can't be strapped in too tight.

Bill Daniels

On 6 Jun 2004 16:55:50 GMT, Ian Cant
wrote:

The 'crotch strap' is what used to be known as a 'negative-G'
strap. Usually it works to keep your skull away from
the canopy during the bumpy bits of sky; rarely, it
helps you in a crash by preventing submarining. However,
a single strap is both inconvenient and potentially
painful. A better design is a double strap, like an
inverted V, but it needs two hard points. Another
variation is an upright V, with one hardpoint and some
secure way to fasten the ends of the V to the lapstraps
rather than the buckle.

I followed the link to Willans Harnesses in "plastic guy's" post and
moused round the site a little. They supply a Y-strap that's designed
to connect to the 5th slot on their quick release fitting, passes
under your legs and attaches to the lap strap hard points. They say
its designed to upgrade their 4-point racing car harnesses to 6-point
standard.

This looks potentially like a quick and easy way to upgrade a 4-point
harness because it requires no extra hard points in the glider.
Presumably the lap strap hard points are already designed to take the
full deceleration loads in a crash so fitting it would not put
additional loads on them.

Does anybody on here know if this upgrade has been done?

If so, how does it compare with a traditional 5-point system with
regard to anti-submarining and negative-G properties?

Are our 5-point rotary action quick-release units the same as the car
racing gang use?


--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

Dale Thompson and I had an inverted V crotch strap in our 1-35. It served to
keep the lap belt in position. More important was the assurance that the
legs and hips would probably take the stress instead of other more
"important" parts that could not be so easily repaired.

Fortunately, we never had a test of its effectiveness.

The design is very simple and easily made. Our was made by Alan Silver, in
the San Francisco bay area, who repacked our chute. I do not think he is
still in business.


"Martin Gregorie" wrote in message
...
On 6 Jun 2004 16:55:50 GMT, Ian Cant
wrote:

The 'crotch strap' is what used to be known as a 'negative-G'
strap. Usually it works to keep your skull away from
the canopy during the bumpy bits of sky; rarely, it
helps you in a crash by preventing submarining. However,
a single strap is both inconvenient and potentially
painful. A better design is a double strap, like an
inverted V, but it needs two hard points. Another
variation is an upright V, with one hardpoint and some
secure way to fasten the ends of the V to the lapstraps
rather than the buckle.

I followed the link to Willans Harnesses in "plastic guy's" post and
moused round the site a little. They supply a Y-strap that's designed
to connect to the 5th slot on their quick release fitting, passes
under your legs and attaches to the lap strap hard points. They say
its designed to upgrade their 4-point racing car harnesses to 6-point
standard.

This looks potentially like a quick and easy way to upgrade a 4-point
harness because it requires no extra hard points in the glider.
Presumably the lap strap hard points are already designed to take the
full deceleration loads in a crash so fitting it would not put
additional loads on them.

Does anybody on here know if this upgrade has been done?

If so, how does it compare with a traditional 5-point system with
regard to anti-submarining and negative-G properties?

Are our 5-point rotary action quick-release units the same as the car
racing gang use?


--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

Alan Silver is very much still in business. See http://www.pia.com/silver/
-Bob Korves
LAK-17a "5K
DuoDiscus "5H"

"Dusty" wrote in message
m...
Dale Thompson and I had an inverted V crotch strap in our 1-35. It served
to
keep the lap belt in position. More important was the assurance that the
legs and hips would probably take the stress instead of other more
"important" parts that could not be so easily repaired.

Fortunately, we never had a test of its effectiveness.

The design is very simple and easily made. Our was made by Alan Silver, in
the San Francisco bay area, who repacked our chute. I do not think he is
still in business.

On Sunday, June 6, 2004 9:26:17 PM UTC-5, Bob Korves wrote:
Alan Silver is very much still in business. See http://www.pia.com/silver/

That pia URL seems faulty. I have the following URL for Allen Silver's 5 point harness and you can order the crotch strap as a separate item.

http://silverparachutes.com/acrobelt/

BTW: We had Allen as a speaker at the ChicagoLand Glider Council's bi-annual conference and he was GREAT. http://silverparachutes.com/safety-seminars/

- John