paulhus@euclid.DEC (05/08/85)
In response to a slightly erroneous description of racing drivers' restraint systems: The typical racing driver does use a 6-point harness, but it goes as follows - All straps meet at a single connector located where your belt buckle would be (very close to your c.g.); they are 1) a pair of two inch wide straps going over your shoulders, connecting to two hard points located about 45 deg down from your shoulders (straight back is out, 2 into 1 is out). 2) a pair of 3 or 4 inch wide straps passing over your forward upper pelvic prominences (don't know the proper term) and going back at about a 30 deg angle to hard points in the vehicle floor or chassis. 3) a pair of anti-submarine belts going from the connector, between your legs, out sideways under your legs and back to hard points (may share hard points with pelvic belts). To generate sufficient anti-submarining forces, the seat would have to tilt up at such an angle that the driver's knees would interfere with the steering wheel. (We're talking 40 g impact forces here. Street cars are not designed to such high limits so anti-submarining can be effectively incorporated in their seats - but usually isn't. Sit in a properly installed street Recaro seat to see how much tilt you need, then imagine a lot more for a race car - ya can't do it. That's why the anti-submarining straps (3) above. Chest straps aren't used (except in some of Stapp's rocket sled work) because you don't want to constrict breathing. NOTE: to work effectively, ALL straps are worn VERY TIGHTLY to prevent momentum/impact effects (you don't want your body to generate any velocity relative to the car's structure). And speaking of breathing, the gas fed to helmets is air, not oxygen - to prevent fire intensification. In oval track racing, an additional strap is sometimes used to aid your neck in keeping your head from tilting outward - it runs from a connector on the helmet looping down under your inner armpit and back. High-G road racers used a padded collar to get a similar assist, but on both sides. Some oval racers use a collar too. two-cents worth from: N. Chris Paulhus DEC-Maynard decwrl!dec-10382!dec-euclid!paulhus