"wright1902glider" wrote


I've been thinking about this a lot in the past few days, and I keep
coming back to the conclusion that I've got more of a height-to-track
ratio problem or a CG problem than a sway issue. From my rear-view
mirror observations, the trailer doesn't sway so much as it just rocks
up on one wheel. I can push on the side of the trailer near the tail
end and in 3-5 pushes, rock it up and nearly over.

Good golly , yes, on the CG problem. That thing is a lot taller than I had
imagined.

I have another insight into your problem.

I think the axle being so far towards the rear is a major part of the tipover.
You have a magjority of your weight on the ball. That is like having a bunch of
weight sitting on a knife edge, just waiting to tip over.

You seriously need to figure out how far forward you can move the axle. It
needs to be forward just to the point of swaying. If the load is even from
front to back, it should place the axle at 60/40. You look to have the axle
like 80/20.

Look at it this way. If the axle is 6 feet from the back, then the weight that
is on the back 6 feet, and 6 feet in front of the axle is using the axle to keep
it stable from side to side. All of the weight in front of that is sitting on a
ball, wanting to flip either left or right. More weight needs to be on the
axle! From your description of pusing it, the springs need to be more stiff,
or have shocks on it. Wider would be better, also, as you say.

Jim, I had been thinking about the ballast system. The local glider FBO
in Boulder, who is also an RAH'er suggested something like this. But
the idea for the pump is the missing link. I can see it helping
considerably on the Interstates. Maybe something like a 12v bilge pump
plumbed between two tanks made from large diameter PVC. Sling 'em low
and to the sides like the external fuel tanks on a CH-53 Sea Stallion.
I've also thought about just adding a concrete-filled steel pipe under
the chassis center to act like the keel of a sailboat. All of this will
require testing of course.

I would thing bigger than pipe would be needed. How about plastic chemical
drums? If you used pipe, you would need to have a low point for the water to
collect for the bilge pump, or any pump to work.

A bilge pump would work very well. They usually have automatic shutoffs, when
they pump dry. All you have to do is pick which tank you want to be empty, and
turn that power supply on and leave it on. If a check valve is not incuded in
the pump, you would want to put one in, to keep the pump off after it transfers.
One pump per tank (or side), two wires going to the cab, a three position
switch, and you have it licked! For equal weight on each side, you would have
to time how long it takes to go from empty to equal, then use that figure to run
a pump and then swtch it off.

Anyone have any thoughts on how much wider I could make the axle? Keep
in mind, the chassis is on 48" spring centers, using 2-leaf
slipper-springs, and currently has a hubface-to-hubface measurement of
60". I've seen heavy air-compressors, like those you see powering
jackhammers, rolling on 3-4' spring centers with about a 6' axle. But
all of the suspension components looked very heavy. My chasis is so
light that I'm concerned about adding too much axle and overloading the
frame attachment points, shackles, etc. with dynamic loads.

If you are concerned about point attachment loads, you could put a heavier angle
iron, or U channel over the existing frme, as a doubler. Make it long enough to
go about 3 feet past the attach points, and that should spread the load well
enough. If you are going to go to a wider axle, it would help to go as wide as
is reasonable, say a shade under 8 feet. Changing the spring fittings on the
axle to match your frame should not be a big deal, with a little welding. While
you are at it, move that darn axle forward, too!
--
Jim in NC