Komet trailer tires

On Feb 25, 5:49*am, vontresc wrote:
On Feb 25, 12:03*am, "Morgans" wrote:



"HL Falbaum" wrote

It is a good idea to have options. So, if someone else has to come get you
with their car, they are likely to have a 1 7/8" or a 2" ball.

It would be easy to replace the hitch on the trailer with either a 2" or 1
7/8" . These are commonly available, just bolt on. Then sell the 50mm
ball.

For little money, a welding shop could make a custom mount---50mm ball
with 1" shank into 2"x 1/4"x 1/4" square tube, welded onto 1 1/4 " tubing
stub and insert into your receiver.

50mm hitch on 1 7/8" ball is just a little sloppy--probably a minor
factor, but best to change something.

*I agree. *Get a welding shop (if you are not able to do it yourself) to
change out the trailer hitch for a standard size like 2". *(standard in this
area, anyway) *Also, custom fit the 1 1/4" stub to your receiver. *I have
usually found they fit loose as crap, unless you do something to make it fit
right.

I had good luck doing this by running two beads of weld down the length of
the hitch stub on two adjacent sides of the stub, then grind it down to a
"just right - slide in, but no wobble" fit. *It is amazing how that can
reduce sway, and quiet down the ride down the road.

Anyone else with a sway problem have a sloppy fitting hitch - receiver fit?
Anyone do something to tighten up the fit?
--
Jim in NC

Ok there seems to be a lot of OWT, and other imprecise anecdotal
evidence about trailers and towing floating out there. Has anyone like
an AKAFLIEG group ever done some trailer dynamocs studies????

Peter

This is a favorite wintertime thread & is as regular as the leaves
turning colors.
Rigorous engineering work has been done on this subject. See article
by Funston in Technical Soaring July 1989, p90-95.

Can't wait for flying to start.

Craig

Morgans wrote:
50mm hitch on 1 7/8" ball is just a little sloppy--probably a minor
factor, but best to change something.


I agree. Get a welding shop (if you are not able to do it yourself) to
change out the trailer hitch for a standard size like 2". (standard in this
area, anyway) Also, custom fit the 1 1/4" stub to your receiver. I have
usually found they fit loose as crap, unless you do something to make it fit
right.

I had good luck doing this by running two beads of weld down the length of
the hitch stub on two adjacent sides of the stub, then grind it down to a
"just right - slide in, but no wobble" fit. It is amazing how that can
reduce sway, and quiet down the ride down the road.

Anyone else with a sway problem have a sloppy fitting hitch - receiver fit?
Anyone do something to tighten up the fit?

It seems remarkable and counter-intuitive that even 1/8" (a lot more
than my hitches) of total slop at one end of a 30 foot long trailer
could have any influence at all. Since the tires are approximately in
the middle, that'd be only an 1/8" at the tail. My trailer is stable,
yet I can still see the tail wagging 1 to 3 inches at times as I'm
driving, far more than a loose hitch would cause.

Perhaps there were some other changes made at the same time, like
changing tire pressures, moving stuff around in the trailer?

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm http://tinyurl.com/yb3xywl

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what you need to know tinyurl.com/yfs7tnz

"Burt Compton - Marfa" wrote

You asked if "anyone do something to tighten up the fit?"
so I offered readers the off-the-shelf J-Bolt idea as an additional
method.

Yep, and I like it. I think it is likely a good product, but pricey, and
possibly too much hassle for some. Ideal for those who can leave the same
hitch in nearly all of the time, I would think.
--
Jim in NC

"Eric Greenwell" wrote
It seems remarkable and counter-intuitive that even 1/8" (a lot more
than my hitches) of total slop at one end of a 30 foot long trailer could
have any influence at all. Since the tires are approximately in the
middle, that'd be only an 1/8" at the tail. My trailer is stable, yet I
can still see the tail wagging 1 to 3 inches at times as I'm driving, far
more than a loose hitch would cause.

Probably true. I stated that a bit strongly, perhaps. The loose hitch
probably does not do much to cause a sway.

If a trailer was verging on unstable, it could be conceiveable that it would
only take a small factor to start exciting the system, and then the trailer
allows the oscillations to amplify and build on their own.

Sway is like a harmonic vibration. If it starts to vibrate, or sway, it can
self excite and built on the small wiggle that got it started.

Still, I guess what I was meaning to ask was if people had a sloppy fit that
rattled back and forth that they had to deal with. I can not stand to hear
something like a loose hitch rattle as I head on down the road. Something
had to be done, and the welds are what I came up with. I tried the metal
shims (like the nails that someone mentioned) and they eventually fell out.
I put my gray matter to the problem and the welds building the fit tighter
is what I ended up going with.
--
Jim in NC

Perhaps there were some other changes made at the same time, like changing
tire pressures, moving stuff around in the trailer?

--
Eric Greenwell - Washington State, USA (netto to net to email me)

- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

- "A Guide to Self-launching Sailplane Operation Mar/2004" Much of what
you need to know tinyurl.com/yfs7tnz

I'd love to read this article. Got a link? Or can you send me an
electronic copy? Thanks!

-John


On Feb 25, 9:59 pm, Craig wrote:
This is a favorite wintertime thread & is as regular as the leaves
turning colors.
Rigorous engineering work has been done on this subject. See article
by Funston in Technical Soaring July 1989, p90-95.

On Feb 26, 4:57*am, jcarlyle wrote:
I'd love to read this article. Got a link? Or can you send me an
electronic copy? Thanks!

-John

On Feb 25, 9:59 pm, Craig wrote:

This is a favorite wintertime thread & is as regular as the leaves
turning colors.
Rigorous engineering work has been done on this subject. See article
by Funston in Technical Soaring July 1989, p90-95.

I went searching last night for a copy and was unable to find
anything. Hopefully the Technical Soaring series will be included in
SSA's scanning project. I can get you in touch with the Author if you
want to contact me by email. You can find a number of threads that
include some of the results if you put "funston trailer sway" into the
group search.

The primary conclusion is to have the axle(s) as far back as possible
while maintaining a reasonable tongue weight. Reducing the polar
moment of inertia of the trailer + glider is useful, but there isn't
much we can do about the mass distribution of the sailplane. From a
towing standpoint the most effective solution is to turn the trailer
around so the wing roots are at the back of the trailer. This allows
moving the axle rearward while maintaining very reasonable tongue
weight. It does have the disadvantage of requiring assembly over the
tongue of the trailer. Spindleberger is a very knowledgeable trailer
manufacturer, but their decisions have to be driven by what they can
sell and loading over the tongue doesn't sell. The speed limits for
trailers in Germany is also slower than we tend to drive in the US so
the stability issues don't show up. My Komet - minivan combination is
fine up to 100 kph, but is a handful over 115 kph. I've had a tongue
loading trailer in the past and it was rock solid as fast as I wanted
to go. Most times I'd forget it was even behind. Anyways there's
lots of historical discussion on the archive and it's an entertaining
diversion.

Cheers,
Craig

On Feb 26, 1:16*pm, Craig wrote:
On Feb 26, 4:57*am, jcarlyle wrote:

I'd love to read this article. Got a link? Or can you send me an
electronic copy? Thanks!

-John

On Feb 25, 9:59 pm, Craig wrote:

This is a favorite wintertime thread & is as regular as the leaves
turning colors.
Rigorous engineering work has been done on this subject. See article
by Funston in Technical Soaring July 1989, p90-95.

I went searching last night for a copy and was unable to find
anything. *Hopefully the Technical Soaring series will be included in
SSA's scanning project. *I can get you in touch with the Author if you
want to contact me by email. *You can find a number of threads that
include some of the results if you put "funston trailer sway" into the
group search.

The primary conclusion is to have the axle(s) as far back as possible
while maintaining a reasonable tongue weight. *Reducing the polar
moment of inertia of the trailer + glider is useful, but there isn't
much we can do about the mass distribution of the sailplane. *From a
towing standpoint the most effective solution is to turn the trailer
around so the wing roots are at the back of the trailer. *This allows
moving the axle rearward while maintaining very reasonable tongue
weight. *It does have the disadvantage of requiring assembly over the
tongue of the trailer. Spindleberger is a very knowledgeable trailer
manufacturer, but their decisions have to be driven by what they can
sell and loading over the tongue doesn't sell. The speed limits for
trailers in Germany is also slower than we tend to drive in the US so
the stability issues don't show up. *My Komet - minivan combination is
fine up to 100 kph, but is a handful over 115 kph. *I've had a tongue
loading trailer in the past and it was rock solid as fast as I wanted
to go. *Most times I'd forget it was even behind. *Anyways there's
lots of historical discussion on the archive and it's an entertaining
diversion.

Cheers,
Craig

Lots of variables: A few I have learned about:
Flexible tongue. My old PIK trailer had a fairly flexible tongue/
frame. After I rolled it over(another story), I rebuilt with about a 8
inch longer tongue(entend distance between pivot and wheels and one
size larger tubing in frame. Result- trailer that liked to sway then
towed straight as an arrow.
Aft weight in trailer. Take the extra ramp, tail ballast weight, and
other stuff out and move to the front. I have found a perceptible
improvement. This is about polar moment obviously.
From my experience, slightly loose fitting tow adaptors don't mean
squat. If the whole "system" is damped properly, that won't mean a
thing- except for clanky annoying noise.
Snow/ice on trailer - TAKE IT OFF!
Tire inflation- High end of mfr's suggested stiffens sidewalls and
reduces sway.
Tire inflation- car. Pump 'em up. Stiffer helps sway and fuel economy.
Hitch overhang- keep to a minimum, especially on short wheelbase
vehicles.
Put heavy extra stuff in the vehicle between the wheels. Making the
trailer heavier than needed in front upsets the natuarl suspension
setup in the car.
FWIW
UH

Thank you, Craig! I did a search of RAS, and found some of the threads
you mentioned.

Interesting, your coonclusion about moving the trailer axle back. My
1983 Cobra (with an ASW-19 in it) was an extremely stable trailer. The
2000 Cobra holding my LS8-18 is not nearly as stable. Same car (BMW
530), same tongue weight (100 lbs), same tires (Duro ST175/80R13).
However, the axle for the 2000 Cobra is about 6 feet closer to the
hitch ball (factory positioning). The new trailer is also taller than
the old one, and doesn't have the lowered front that the old trailer
did, either. I'm sure that Herr Spindelberger had a reason for the
axle placement (maybe the 18 m tips being carried at the top rear?),
but I'm thinking about moving the axle back a few feet.

Regards,
John

On Feb 26, 1:16 pm, Craig wrote:
I went searching last night for a copy and was unable to find
anything. Hopefully the Technical Soaring series will be included in
SSA's scanning project. I can get you in touch with the Author if you
want to contact me by email. You can find a number of threads that
include some of the results if you put "funston trailer sway" into the
group search.

The primary conclusion is to have the axle(s) as far back as possible
while maintaining a reasonable tongue weight. Reducing the polar
moment of inertia of the trailer + glider is useful, but there isn't
much we can do about the mass distribution of the sailplane. From a
towing standpoint the most effective solution is to turn the trailer
around so the wing roots are at the back of the trailer. This allows
moving the axle rearward while maintaining very reasonable tongue
weight. It does have the disadvantage of requiring assembly over the
tongue of the trailer. Spindleberger is a very knowledgeable trailer
manufacturer, but their decisions have to be driven by what they can
sell and loading over the tongue doesn't sell. The speed limits for
trailers in Germany is also slower than we tend to drive in the US so
the stability issues don't show up. My Komet - minivan combination is
fine up to 100 kph, but is a handful over 115 kph. I've had a tongue
loading trailer in the past and it was rock solid as fast as I wanted
to go. Most times I'd forget it was even behind. Anyways there's
lots of historical discussion on the archive and it's an entertaining
diversion.

On Feb 26, 11:56*am, jcarlyle wrote:
Thank you, Craig! I did a search of RAS, and found some of the threads
you mentioned.

Interesting, your coonclusion about moving the trailer axle back. My
1983 Cobra (with an ASW-19 in it) was an extremely stable trailer. The
2000 Cobra holding my LS8-18 is not nearly as stable. Same car (BMW
530), same tongue weight (100 lbs), same tires (Duro ST175/80R13).
However, the axle for the 2000 Cobra is about 6 feet closer to the
hitch ball (factory positioning). The new trailer is also taller than
the old one, and doesn't have the lowered front that the old trailer
did, either. *I'm sure that Herr Spindelberger had a reason for the
axle placement (maybe the 18 m tips being carried at the top rear?),
but I'm thinking about moving the axle back a few feet.

Regards,
John

On Feb 26, 1:16 pm, Craig wrote:

I went searching last night for a copy and was unable to find
anything. *Hopefully the Technical Soaring series will be included in
SSA's scanning project. *I can get you in touch with the Author if you
want to contact me by email. *You can find a number of threads that
include some of the results if you put "funston trailer sway" into the
group search.

The primary conclusion is to have the axle(s) as far back as possible
while maintaining a reasonable tongue weight. *Reducing the polar
moment of inertia of the trailer + glider is useful, but there isn't
much we can do about the mass distribution of the sailplane. *From a
towing standpoint the most effective solution is to turn the trailer
around so the wing roots are at the back of the trailer. *This allows
moving the axle rearward while maintaining very reasonable tongue
weight. *It does have the disadvantage of requiring assembly over the
tongue of the trailer. Spindleberger is a very knowledgeable trailer
manufacturer, but their decisions have to be driven by what they can
sell and loading over the tongue doesn't sell. The speed limits for
trailers in Germany is also slower than we tend to drive in the US so
the stability issues don't show up. *My Komet - minivan combination is
fine up to 100 kph, but is a handful over 115 kph. *I've had a tongue
loading trailer in the past and it was rock solid as fast as I wanted
to go. *Most times I'd forget it was even behind. *Anyways there's
lots of historical discussion on the archive and it's an entertaining
diversion.

Interesting comparison of the two trailers. Moving the axle back even
a fraction of a foot can sometimes be enough to make a noticeable
difference. Hank's comment about longer tongues is also a good one.
I've pulled a Schreder trailer with a 15m ship that had a custom
extended tongue made of aluminum to keep the weight down. That
trailer also towed very well.

Craig

"jcarlyle" wrote

same tongue weight (100 lbs)

Wow, that seems light. What is the overall weight of the trailer?
--
Jim in NC