Below is my reply to Jeff. I do believe that if you use the standard
hardpoints and regular belts that you should at least use a CS stainless
washer under the screw. This will spread the load on the glass and make a
pull though more difficult.
don't know for sure but the total weight of four AMSAFE belts IIRC is less
than 10 pounds. Incrementally I would say an additional 2-4 pounds over the
standard belts. You add 4 3'x3'x1/2'' aluminum blocks and four rollers Check
with Rene as he probably weighed the alternatives.
The existing hardpoints were deemed inadequate (for the AMSAFE application)
by both AMSAFE and consultant (PhD, ME Caltech) who lives nearby. The vans
hardpoints are setup for a single #5 counter sunk screw. This is installed
without CS washer that would be required to spread the load. My ME
consultant friend tells me that the normal use of the regular belts will
cause micro fractures and may fail (pull through) if and when a crash
occurs. AMSAFE commented that they would sell me the belts if I "beefed up"
the existing hardpoints. Since the roller have screws for attaching the
brackets I needed a means to attach the bracket Since I did not want 16
protruding though the lid I used the aluminum blocks (2024T3 or 7075) .
These were tapped for 4 external screws to hold the pad that holds the
roller. Each external screw has a .75" CS stainless washer and thereby
spreading the load on the lid. In addition since the shoulder straps are on
inertial reels there is no constant shear load on the single screw in the
lid. The hardpoints areas were strengthened by additional E-glass and
S-glass tapes. The calculations of the ME ,while informal, indicated that
relative strengths could compared by comparing the surface areas of the
fasteners. Hope this helps.
I've got a couple of questions David:
How much weight are we adding with the inertia reel belts as opposed to the
standard?
The hard points you show in you installation pictures are much more
elaborate than what Vans provides for the stock belts. Is there a reason
the inertia belts require more support, or do you feel the Vans hard points
aren't enough for either approach
_____
From: owner-rv10-list-server@matronics.com
[mailto:owner-rv10-list-server@matronics.com] On Behalf Of RV Builder
(Michael Sausen)
Sent: Thursday, November 05, 2009 7:01 PM
To: rv10-list@matronics.com
Subject: RE: AMSAFE seat belts
I think the overall concern is that the factory hardpoints are just not
enough. I believe, as David said, AMSafe was concerned that additional
reinforcement would up the safety margin. I know I feel a lot better after
putting a couple of intersecting layers of S glass over the hardpoints.
Michael
From: owner-rv10-list-server@matronics.com
[mailto:owner-rv10-list-server@matronics.com] On Behalf Of Jeff Carpenter
Sent: Thursday, November 05, 2009 4:20 PM
To: rv10-list@matronics.com
Subject: Re: AMSAFE seat belts
I've got a couple of questions David:
How much weight are we adding with the inertia reel belts as opposed to the
standard?
The hard points you show in you installation pictures are much more
elaborate than what Vans provides for the stock belts. Is there a reason
the inertia belts require more support, or do you feel the Vans hard points
aren't enough for either approach?
Jeff Carpenter
40304
Finishing the inside of the cabin top... and making provisions for the belts
On Nov 3, 2009, at 9:46 AM, David McNeill wrote:
www.inertialbelts.com is on line again. The belts are shown in my Glastar as
the belts were not installed in my 10 at that time. Rene has good pictures
of the final finish. I will enclose one of his here.
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