Post by planeimages on Mar 30, 2007 17:49:59 GMT 12
Looking at motor racing as a comparison of belts and stretch, one of the problems in sedans is the tendency for builders to attach the shoulder straps to the rear "parcel shelf" area (suitably re-inforced or using a standard safety belt mount or part of the cage.
This procedure gives the same potential problem of the long tail and attendant webbing stretch.
Current Australian requirements call for a "taxi bar" or similar structure behind the driver's or navigator's seat to which the shoulder steaps must be attached.
To prevent sideways movement in a lateral impact, the belts must be prevented from moving. Flanges on the cross tube where the belts are wrapped around the tube are required. If the belts are bolted in then that problem does not arise.
Having said all that one should cast one's mind back to Mikka Hakkinen's prang at Adelaide in the AGP some years ago in his McLaren. He head-butted the steering wheel despite being secured by 75mm wide shoulder straps affixed iin close proximity to his body... as close as a belt could ever be.
One can only imagine where the stretch came from.. not much from the belts and the wheel did not come back to meet him. The human body can withstand incredible amounts of stretch, so I am led to believe. Analysis of the trauma suffered by rear seat occupants in road MVAs indicates that a great deal of neck and body stretching occurs and is, in many cases, survivable.
Every time I board a commercial aircraft and listen to the safety briefing I have trouble controlling my warped sense of humour when they come to the part which advises pax to put their head between their knees if they cannot take up the standard brace position of head on hands on the seat back in front of them.. "place your head between your knees" (and kiss your ass goodbye) is the addendum I hear my inner voice say.
This procedure gives the same potential problem of the long tail and attendant webbing stretch.
Current Australian requirements call for a "taxi bar" or similar structure behind the driver's or navigator's seat to which the shoulder steaps must be attached.
To prevent sideways movement in a lateral impact, the belts must be prevented from moving. Flanges on the cross tube where the belts are wrapped around the tube are required. If the belts are bolted in then that problem does not arise.
Having said all that one should cast one's mind back to Mikka Hakkinen's prang at Adelaide in the AGP some years ago in his McLaren. He head-butted the steering wheel despite being secured by 75mm wide shoulder straps affixed iin close proximity to his body... as close as a belt could ever be.
One can only imagine where the stretch came from.. not much from the belts and the wheel did not come back to meet him. The human body can withstand incredible amounts of stretch, so I am led to believe. Analysis of the trauma suffered by rear seat occupants in road MVAs indicates that a great deal of neck and body stretching occurs and is, in many cases, survivable.
Every time I board a commercial aircraft and listen to the safety briefing I have trouble controlling my warped sense of humour when they come to the part which advises pax to put their head between their knees if they cannot take up the standard brace position of head on hands on the seat back in front of them.. "place your head between your knees" (and kiss your ass goodbye) is the addendum I hear my inner voice say.
