S-H safety harness (V2C)

Ray,

I know (hope) your statement was tongue-in-cheek, but it is worth a
comment. Your "spare tire" (or even your six-pack abs) won't prevent
you from submarining. Your lap belts must be and stay securely
locked down on your pelvis. I have an article from one of the auto
racing labs which shows that your pelvis can withstand 5,000 lbs of
force whereas the soft organs of your gut will be severely compromised
at less than 800. Assuming in a crash that the straps around your
middle take 50% of the load (obviously, that will depend on many
factors - crash angle, deceleration mode, etc. etc.), that still means
that anything approaching an 8g deceleration (maybe less) will be
serious trouble. Now, that's an otherwise survivable crash, so it
would be a shame to have a problem. Especially in the older,
flatter seat pans, it doesn't take an especially creative mind to
visualize the submarining that happens without a properly secured lap
belt.

Erik Mann
LS8-18 (P3)

Erik,

It was, although "butt in sling" or something similar might better
"fit" the situation. The whole point of that 5th strap is to keep the
lap belts properly positioned on the pelvis and still allow the
shoulder belts to be tight. This positioning gives the best control of
both vertical and horizontal motion. In the case of a really high g
impact in a glider I suspect restraint issues would be moot, however.

There's been a lot of research on making high speed racecar crashes
survivable; there's both interest and funding for it, very little on GA
and only a bit in gliders. The key lessons from Nascar and Grand Prix
racing are that a cockpit that maintains its integrety and a restraint
system that keeps the driver within that container are good things.
Nascar has now mandated a separate head restraint to prevent neck
injuries. These measures have made at least some 200 mph crashes
survivable.

Bringing measures of this kind to gliders would require that we be
willing to pay for them, something, according to the DG newsletter, we,
as a group, are not willing to do.

Ray Warshaw
1LK

wrote:
An annoying property of my Ventus 2C is that the safety harness does
not hold me into the seat. When encountering turbulance my upper torso
leaves the seat and my head ocassionally hits the canopy.

The position of the shoulder strap anchors aft of the cockpit is high
enough that no downward force is exerted no matter how much the straps
are tightened. The only thing this achieves is pulling the buckle up
away from my abdomen.

Are there any solutions or workarounds for this prollum? (Besides
padding my hat?)

~ted/2NO


Same problem in my Discus A. There is space between the shoulder straps
and my shoulders.

Shoulder straps are supposed to hold you back from moving *forward*. Belly
straps are supposed to hold you *down*. The crotch strap is suppposed to
keep the belly straps in position.

"Greg Arnold" . wrote in message
news:lI83g.3806$_c1.175@fed1read05...
wrote:
An annoying property of my Ventus 2C is that the safety harness does
not hold me into the seat. When encountering turbulance my upper torso
leaves the seat and my head ocassionally hits the canopy.

The position of the shoulder strap anchors aft of the cockpit is high
enough that no downward force is exerted no matter how much the straps
are tightened. The only thing this achieves is pulling the buckle up
away from my abdomen.

Are there any solutions or workarounds for this prollum? (Besides
padding my hat?)

~ted/2NO


Same problem in my Discus A. There is space between the shoulder straps
and my shoulders.

Properly positioned lap belts control both vertical and horizontal
motion. The shoulder belts keep the torso from pivoting forward and
the crotch strap keeps the lap belts in place. Note that the crotch
strap need not actually contact your crotch to properly perform this
function. My recollection of the racecar research is that, in a
reclined seating position, a substantial portion of the force on the
shoulder belts is transfered downward and captured by the lap belts.

Ray Warshaw

At 19:18 24 April 2006, wrote:
I have a 4-point system. What's involved with getting
a 6-point
harness?

Ray: how do you reconcile a crotch strap and a pilot
relief system?


I've never seen a six point for real but this is what's
involved:
http://www.lukeracing.co.uk/anat.php
There's also this company:
http://www.willansharness.com/

I think straps 5 & 6 are attached to the same hardpoints
as the lapstraps and prevent the buckle from sliding
up every time you tighten your shoulder straps.

Edward

wrote:
An annoying property of my Ventus 2C is that the safety harness does
not hold me into the seat. When encountering turbulance my upper torso
leaves the seat and my head ocassionally hits the canopy.

The position of the shoulder strap anchors aft of the cockpit is high
enough that no downward force is exerted no matter how much the straps
are tightened. The only thing this achieves is pulling the buckle up
away from my abdomen.

Are there any solutions or workarounds for this prollum? (Besides
padding my hat?)

~ted/2NO

Ted-
Design is done that way to prevent compression of spine in an accident.
Solution to your problem as noted elsewhere is 5th point holding seat
belts down and forward. Your belt should have provisions for this 5th
point in the latch.
Good luck
UH

I'm going to give this 5th point thing (crotch strap) a try but I'll
have to have the anchor point on the seat pan just below the stick boot
around where the factory relief tub hole is drilled. (I made a new hole
for that several inches farther aft.)

Thanks to everyone who responded by e-mail, I appreciate it very much.

~ted/2NO

Go to groups.google.com and do a search for the "Glider harnesses, 4
versus 5-point" thread back in 1998. There is some specific information
about the pros/cons of various types of safety harnesses and how to
modify existing gliders.

Chip Bearden
ASW 24 "JB"