At 05:42 23 December 2019, wrote:
On Monday, December 16, 2019 at 2:03:02 PM UTC-6, princiar
wrote:
Anyone has experience towing a trailer with a car with the trailer
sway
m=
itigation installed?

Check out this technical paper
(https://purehost.bath.ac.uk/ws/portalfiles/=
portal/147993632/JAUTO981.pdf); it is really pretty easy to digest.

Figures 9-14 provide the important results. Figure 10 shows that
minimizin=
g the yaw inertia of the trailer provides the largest impact on
damping
rat=
io, and thus the safe towing speed. Figure 9 shows that adding
tongue
weig=
ht above about 6-7% does not really improve the speed very
much. Figure
11=
shows that changes in the overall trailer mass do not greatly
impact the
s=
afe towing speed. Figure 13 shows that making a large change in
tire
press=
ure (from 30 to 40 psi) only changes the speed for the same
damping ratio
b=
y a couple of mph. Figure 14 shows that adding a friction stabilizer
likew=
ise only changes the speed a couple of mph.

Most composite glider since the 1970s load the wing roots to the
front of
t=
he trailer, and this directly helps lower the yaw inertia of the trailer.

=
However, many older wood gliders with large root chords load the
wing
roots=
aft. For these trailers, the axle must be mounted further aft to
help
con=
trol the yaw inertia so that the trailer can be pulled at highway
speeds.
=
Trailers that load over the tongue should have the wing roots
forward, and
=
these should be similar to more modern trailers. I have one of
these for
a=
Ka-6, and it is a real detriment for drag with the big flat door
directly
=
into the wind, even behind a full-size van.

As for tires, if one wants to travel above 65 mph, trailer tires are
probab=
ly not what you want, since it is above their speed rating. If you
drive
o=
n Interstate highways, this could be an issue, unless you are
comfortable
b=
acking up traffic. I myself prefer the radial tires that are not speed
lim=
ited (at least to normal road speed limits) and are likely to give a
smooth=
er ride for my glider as well. =20

As long as I load the trailer to have a safe margin with damping
ratio and
=
I have reasonable pressure in the tires, I have towed single-seat
trailers
=
with my Ford E-150 passenger van, my wife's 1999 Volvo V70, my
2003 Ford
Fo=
cus, or even years ago, my old 1981 Volvo 245. Towing with the
245 (108
hp=
max at SL) limited my speed significantly when climbing over
mountain
pass=
es in Oregon, but it did okay on the level, albeit normally not using
overd=
rive. One should also respect the max speed when towing with a
smaller
car=
though, because of the time, distance, and stability to do a panic
stop
wi=
th the increase in total weight.

Read the paper and try not to overthink this topic. Load your
trailer
prop=
erly, air up whatever tires you choose, and drive safely.

... Neal P.

What is worth remembering is that the cause of the sway is
aerodynamic. Loading, tyre pressure, fiction dampers can only
ensure that the sway is damped out and does not increase. Trailers
with less vertical surface area aft of the wheels suffer less from
snaking than those with equal or greater vertical surface area behind
the wheels. You may not be able to change the aerodynamics of the
trailer but a good friction damper and proper loading will normally
ensure that the snaking is damped.
I have been a passenger in a car towing a Cobra trailer at over
100mph, scared the crap out of me but it was completely stable, but
only when loaded with the glider. Empty it was a different story.