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owly · 09-09-2013, 03:52 PM

Kenny's comments are very valid.......... The weight distribution is much too far aft. The optimal weight distribution would probably have the axle right under your butt in this case.
One of the reasons I always get back to rear steering is weight distribution. With the engine in the front and two wheel drive, the passengers can sit further back. The front wheels can be non steering so there are minimal fenders impinging on cabin area, and the wheels can be completely skirted. The rear wheel which would steer can be completely enclosed under the body work.
Rear steer positive stability would be achieved by putting the kingpin axis behind the contact point of the tire, and using positive caster. This would apply a force back to center that would be stronger the more centrifugal force there was, as opposed to trailing, where sideways force would want to push you tighter into the turn. I've been a Buckminster Fuller admirer since the 60's........ so I'm biased toward the Dymaxion. I only wish there was some info about his rear steering geometry available on the web.... Thus far I've had no luck. The downfall of the Dymaxion I believe was the weight distribution.

Howard

QUOTE=Kenny;379285]Given a single rear wheel, there is essentially no roll stability at the rear. Since it isn't a 'tilter', the front axle (w/two wheels) provides the only roll stability for the entire vehicle. Also, the 3-wheeled configuration gets complex when suspension is involved because the suspended front axle will allow a given amount of roll, exacerbating the tendency to lean in corners. Just a suggestion, but I would strongly encourage a minimum weight distribution of 65% front/35% rear, and a stiff anti-sway bar on the front. Yes, agreed, keep the mass as low as possible... especially on the rear half of the chassis.

At 500 lbs total, you can probably get away with using bathroom scales under each wheel. This will easily ballpark your weight distribution (given approx. 33% under each wheel). If only one scale is available, just make sure the vehicle is level by using blocks or spacers under the other two wheels when weighing.

-kenny-[/QUOTE]

09-09-2013, 03:52 PM	#86 (permalink)
owly EcoModding Lurker Join Date: Jan 2010 Location: Montana Posts: 33 Thanks: 0 Thanked 26 Times in 10 Posts	Roll stability Kenny's comments are very valid.......... The weight distribution is much too far aft. The optimal weight distribution would probably have the axle right under your butt in this case. One of the reasons I always get back to rear steering is weight distribution. With the engine in the front and two wheel drive, the passengers can sit further back. The front wheels can be non steering so there are minimal fenders impinging on cabin area, and the wheels can be completely skirted. The rear wheel which would steer can be completely enclosed under the body work. Rear steer positive stability would be achieved by putting the kingpin axis behind the contact point of the tire, and using positive caster. This would apply a force back to center that would be stronger the more centrifugal force there was, as opposed to trailing, where sideways force would want to push you tighter into the turn. I've been a Buckminster Fuller admirer since the 60's........ so I'm biased toward the Dymaxion. I only wish there was some info about his rear steering geometry available on the web.... Thus far I've had no luck. The downfall of the Dymaxion I believe was the weight distribution. Howard QUOTE=Kenny;379285]Given a single rear wheel, there is essentially no roll stability at the rear. Since it isn't a 'tilter', the front axle (w/two wheels) provides the only roll stability for the entire vehicle. Also, the 3-wheeled configuration gets complex when suspension is involved because the suspended front axle will allow a given amount of roll, exacerbating the tendency to lean in corners. Just a suggestion, but I would strongly encourage a minimum weight distribution of 65% front/35% rear, and a stiff anti-sway bar on the front. Yes, agreed, keep the mass as low as possible... especially on the rear half of the chassis. At 500 lbs total, you can probably get away with using bathroom scales under each wheel. This will easily ballpark your weight distribution (given approx. 33% under each wheel). If only one scale is available, just make sure the vehicle is level by using blocks or spacers under the other two wheels when weighing. -kenny-[/QUOTE]