Gene Pink
Well-known member
>> the magnet weight isn't on you
> It is when NOT semi-sucking. It's high over your hood.
So?
A couple hundred extra extra pounds about three feet at the most, forward of the front wheels on a 3000# car, might affect the ultimate limits of handling through the slalom course cones a bit. Maybe a noticeable difference in handling, maybe not, but nothing wacky and unsafe for the road.
> > 1/16" necessary
> A truck will *brake* over 0.5G. Since they all have ABS now (since 1996), 0.8G is possible on the best surfaces. Yes, this is relieved when you get on your brakes (or your brake control kicks in), but there will be a lag. Pretty-near the full weight of your car "standing" on 1/16" tube? Plus if the semi is braking hard for a real problem, it may be moving-over in its lane, side-forces.
Hmmm, interesting idea: Trailer surge brake setup between the towbar and the magnet array, perhaps a large spring compressing, actuating a slide pot from an old Yamaha console (I have plenty of spares). The output voltage controls a PWM driven solenoid applying proportional force to the brake pedal in the car.
Naah, too complicated, would cost more than you would save in fuel being a stowaway.
I still stand behind the 1-1/2 square tubing thing, as long as the 30: 1 rule of thumb (*1) isn't violated, 1-1/2 x 1/16" can take tons of compression without buckling, and weighs little. This means up to 45" long arms on the towbar, and they don't need to be that long.
If 1/16" wall bothers you, go with 1/8" wall.
Note: (*1): rule of thumb from machine element design: any structural element under compression stress can have a ratio no greater than 30 : 1, meaning length : width.
Gene
> It is when NOT semi-sucking. It's high over your hood.
So?
A couple hundred extra extra pounds about three feet at the most, forward of the front wheels on a 3000# car, might affect the ultimate limits of handling through the slalom course cones a bit. Maybe a noticeable difference in handling, maybe not, but nothing wacky and unsafe for the road.
> > 1/16" necessary
> A truck will *brake* over 0.5G. Since they all have ABS now (since 1996), 0.8G is possible on the best surfaces. Yes, this is relieved when you get on your brakes (or your brake control kicks in), but there will be a lag. Pretty-near the full weight of your car "standing" on 1/16" tube? Plus if the semi is braking hard for a real problem, it may be moving-over in its lane, side-forces.
Hmmm, interesting idea: Trailer surge brake setup between the towbar and the magnet array, perhaps a large spring compressing, actuating a slide pot from an old Yamaha console (I have plenty of spares). The output voltage controls a PWM driven solenoid applying proportional force to the brake pedal in the car.
Naah, too complicated, would cost more than you would save in fuel being a stowaway.
I still stand behind the 1-1/2 square tubing thing, as long as the 30: 1 rule of thumb (*1) isn't violated, 1-1/2 x 1/16" can take tons of compression without buckling, and weighs little. This means up to 45" long arms on the towbar, and they don't need to be that long.
If 1/16" wall bothers you, go with 1/8" wall.
Note: (*1): rule of thumb from machine element design: any structural element under compression stress can have a ratio no greater than 30 : 1, meaning length : width.
Gene
