I finally installed an Alko AKS 1300 (shown at the
same web site) on my Toyota 4 Runner and Cobra (DG808)
after trying everything else short of relocating the
axle and it worked. Expensive but much less trouble
than reworking the trailer.



At 04:48 15 June 2005, Ian wrote:
On Mon, 13 Jun 2005 08:15:23 -0700, rolfh wrote:

We're towing a DG-500M in a Cobra trailer, and it
has a definite sway,
fortunately it usually damps fairly well. Life was
worse with a strong
crosswind. We had 2 thoughts:
1. tonuge weight - are we shooting for tongue weight
about 10% of the
total trailer weight?
2. Hitch height - any thoughts?

I used to own a half share in a Nimbus 2. My partner
and I had both
previously rolled a glider trailer, writing off the
car, in separate
incidents with different trailers. So when we discovered
the home built
Nimbus trailer could not be towed over 80km/hr we were
determined to fix
it.

Our solution was:

1) We moved the trailer axle back to increase the tow
ball weight. We
aimed for 50kg but ended up with close to 60kg. Up
from about 20kg. 50kg
is near the limit of most cars, above this and you
will need to tow with a
truck.

2) We bought a 'Trapezium' towbar stablizer. This is
a device which
bolts onto the towbar. It has a mechanism which moves
the tow ball from
side to side as the trailer rotates around the tow
ball. The effect
of this is to move the pivot point well forward of
the tow ball, close to
the rear axle of the tow vehicle. This changes the
geometry of the system
and radically reduces the tendency to sway. Google
found a writeup on this
device on the bottom of this page.

http://www.swift-owners-club.co.uk/s...abilisers.html

It is a South African invention, originally developed
by a glider pilot.
It is VERY effective with a glider trailer due to the
length of the
trailer. I don't know whether they are still available,
but if you find
one, be sure to know they work.

These two in combination resulted in a trailer which
was stable at speeds
over 120 km/hr. I was never brave enough to try towing
any faster.

Double axle trailers are also much more stable. If
the mod is done
carefully, adding a second axle to a trailer can often
provide a permanent
fix.

Of course you must have an appropriate tow car. Beware,
modern cars are
lighter, but old glider trailers remain the same.

Many pilots only discover that the car they own is
not suitable for towing
the glider that they fly after they have successfully
completed their
first outlanding. Worst still, the discovery is often
made with an
inexperienced friend driving the car ...

Have fun.

Ian