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trailer sway mitigation TSM



 
 
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  #11  
Old December 17th 19, 02:51 PM posted to rec.aviation.soaring
glidergeek
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Posts: 183
Default trailer sway mitigation TSM

Longer wheelbase on the towing vehicle with a robust suspension.
  #12  
Old December 17th 19, 04:58 PM posted to rec.aviation.soaring
Jonathan St. Cloud
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Posts: 1,463
Default trailer sway mitigation TSM

On Monday, December 16, 2019 at 5:44:28 PM UTC-8, Dave Nadler wrote:
On Monday, December 16, 2019 at 6:41:28 PM UTC-5, Bob Kuykendall wrote:
...These are the things I have done to mitigate trailer sway


Reminds me of when I was a wee glider pilot at MIT Soaring Association.
Instructor: Once, we had a big problem with a trailer swaying.
Dave: So, what did you do?
Instructor: Obviously, we adjusted the center of precussion and moved the axle back.
Dave: So, what happened?
Instructor: It didn't sway anymore, but then the tongue broke off.....

Yup, such was my education.
Couldn't make this stuff up if you tried...


Sounds like a group of scientists, not engineers.
  #13  
Old December 17th 19, 05:06 PM posted to rec.aviation.soaring
Matt Herron Jr.
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Posts: 548
Default trailer sway mitigation TSM

On Monday, December 16, 2019 at 4:43:23 PM UTC-8, JS wrote:
Good shocks seemed to have the biggest effect in my experience.
Look out when moving trailer weight forward... Never exceed the maximum tongue weight!
Jim


Also tighten up the hitch in the receiver with one of these: they take out the slop that can add to sway, and quiet down the rig
  #14  
Old December 17th 19, 06:06 PM posted to rec.aviation.soaring
George Haeh
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Posts: 257
Default trailer sway mitigation TSM

Maximum allowed tire pressure in trailer and rear tow vehicle axle.
  #15  
Old December 17th 19, 06:15 PM posted to rec.aviation.soaring
Jonathan St. Cloud
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Posts: 1,463
Default trailer sway mitigation TSM

On Tuesday, December 17, 2019 at 8:06:29 AM UTC-8, Matt Herron Jr. wrote:
On Monday, December 16, 2019 at 4:43:23 PM UTC-8, JS wrote:
Good shocks seemed to have the biggest effect in my experience.
Look out when moving trailer weight forward... Never exceed the maximum tongue weight!
Jim


Also tighten up the hitch in the receiver with one of these: they take out the slop that can add to sway, and quiet down the rig


I found once I stopped towing with a Jeep Grand Cherokee I had no more sway problems.
  #16  
Old December 17th 19, 07:01 PM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Posts: 1,939
Default trailer sway mitigation TSM

Matt Herron Jr. wrote on 12/17/2019 8:06 AM:
On Monday, December 16, 2019 at 4:43:23 PM UTC-8, JS wrote:
Good shocks seemed to have the biggest effect in my experience.
Look out when moving trailer weight forward... Never exceed the maximum tongue weight!
Jim


Also tighten up the hitch in the receiver with one of these: they take out the slop that can add to sway, and quiet down the rig

That item raised the safe towing speed about 5 mph on my Sienna minivan; raising
the van tire pressure to the value on the door sticker improved it another 3 mph.
Raising the trailer tire pressure to 10 psi over the pressure required for the
load improved it further, but I don't recall the amount it changed.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
  #17  
Old December 17th 19, 07:18 PM posted to rec.aviation.soaring
[email protected]
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Posts: 41
Default trailer sway mitigation TSM

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 mitigation installed?


I posted a link to a short video before, here are better ones from a Prof at the University of Bath:
https://www.youtube.com/watch?v=PFzrWHTG5e8
https://www.youtube.com/watch?v=qEWtBV9I0U4
There are other videos from the University, that I cannot find quickly now, that show this demonstration rig being used where overall weight of the load is maintained, and even tongue weight. All these videos show that placing load aft is the problem (increased yaw inertia, increased polar moment of inertia, ...).

When towing a homemade Ka-6 trailer with a Ford Explorer along I-40 into Santa Rosa about 20 years ago, I had my first experience with trailer instability. The rig was towing fine along at highway speeds on the level, but as I started down the long curving grade into town, the rig started to speed up slightly. At the same time, I got a gust off a semi I was passing and the trailer started to oscillate. I dared not hit the brakes too hard, but I was going down a grade and the rig was trying to pick up speed. The road also had a mild turn to the right, just to aggravate the problem. I firmly held the steering wheel to avoid amplifying the motion and got the rig to slow just enough to be stable again. By this time, the semi and everyone else who had been near me, were over a quarter of a mile behind me. They had all slowed hard to avoid my issue. Before this trip, I screwed down a lightweight plastic tub in the back of the trailer and put two sleeping bags inside for our kids. I did experiments on level ground and found that the weight of those two sleeping bags placed at the back of the trailer would lower the speed for stability by about 10 miles per hour. We found another place for the sleeping bags for the trip home.

I also have a large, eastern-European, box trailer that I haul a Ka-2b in and use for other glider projects, typically with a Ford E-150 van. After loading up a project near Manning, South Carolina, I realized that the rig was neutrally stable at a speed of about 55 mph. Before getting on the interstate highway, I pulled a box of various broken wood pieces (ribs, etc) out of the back of the trailer and put it in my van. This box was not heavy, just large, which is why I put it in the back of the trailer in the first place. This small change allowed me to tow on the interstate comfortably up to about 65 mph with neutral stability being above 70 mph. I accepted that limitation and observed it for the trip back to Kansas.

With my usual Ka-2b glider situated in the large trailer, I have never reached a neutral stability speed. If there had been a problem, I would have moved the axle aft on the trailer to get stability margin for highway speed.

If your trailer has too much weight aft, it will limit the speed you can drive. Tow vehicle size and tire pressures are all factors, but the primary excitation comes from the stability of the trailer itself. If there too much load aft on the trailer, nothing else will prevent the problem.

I check every trailer I tow by increasing speed by steps and checking for stability with a small steering wheel jerk. I don't want any surprises.
  #18  
Old December 17th 19, 07:19 PM posted to rec.aviation.soaring
Boise Pilot
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Posts: 61
Default trailer sway mitigation TSM

On Tuesday, December 17, 2019 at 10:15:29 AM UTC-7, Jonathan St. Cloud wrote:
On Tuesday, December 17, 2019 at 8:06:29 AM UTC-8, Matt Herron Jr. wrote:
On Monday, December 16, 2019 at 4:43:23 PM UTC-8, JS wrote:
Good shocks seemed to have the biggest effect in my experience.

I have used three different model year Jeep Grand Cherokees as tow cars for over 35 years. Nelson Funston (JN) is a tire and trailer expert with big heavy trailers. With my first Jeep, told me to do three things in following order:
-Move some weight forward,-stiffer sidewall trailer tires at max pressure, -vehicle tires at max pressure. Ancillary advice, maintain Jeep shocks... We have some interstate speeds of 80 mph in Idaho. No sway!! All my Jeeps were the 8cyl model so heavier than the old 4cyl and most currently available 6cly on the road. Also all had 4 wheel drive and the off road accessory that has different suspension and road clearance. Boise Pilot




Look out when moving trailer weight forward... Never exceed the maximum tongue weight!
Jim


Also tighten up the hitch in the receiver with one of these: they take out the slop that can add to sway, and quiet down the rig


I found once I stopped towing with a Jeep Grand Cherokee I had no more sway problems.


  #19  
Old December 17th 19, 08:01 PM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Posts: 1,939
Default trailer sway mitigation TSM

Boise Pilot wrote on 12/17/2019 10:19 AM:
On Tuesday, December 17, 2019 at 10:15:29 AM UTC-7, Jonathan St. Cloud wrote:
On Tuesday, December 17, 2019 at 8:06:29 AM UTC-8, Matt Herron Jr. wrote:
On Monday, December 16, 2019 at 4:43:23 PM UTC-8, JS wrote:
Good shocks seemed to have the biggest effect in my experience.

I have used three different model year Jeep Grand Cherokees as tow cars for
over 35 years. Nelson Funston (JN) is a tire and trailer expert with big heavy
trailers. With my first Jeep, told me to do three things in following order:
-Move some weight forward,-stiffer sidewall trailer tires at max pressure,
-vehicle tires at max pressure. Ancillary advice, maintain Jeep shocks... We
have some interstate speeds of 80 mph in Idaho. No sway!! All my Jeeps were
the 8cyl model so heavier than the old 4cyl and most currently available 6cly
on the road. Also all had 4 wheel drive and the off road accessory that has
different suspension and road clearance. Boise Pilot




Look out when moving trailer weight forward... Never exceed the maximum
tongue weight! Jim

Also tighten up the hitch in the receiver with one of these: they take out
the slop that can add to sway, and quiet down the rig


I found once I stopped towing with a Jeep Grand Cherokee I had no more sway
problems.


Anyone that wants to hear more from Nelson Funston can download his OSTIV paper on
trailer stability he

http://journals.sfu.ca/ts/index.php/...wnload/779/737

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
  #20  
Old December 17th 19, 08:30 PM posted to rec.aviation.soaring
Dave Nadler
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Posts: 1,610
Default trailer sway mitigation TSM

On Tuesday, December 17, 2019 at 2:01:56 PM UTC-5, Eric Greenwell wrote:
Boise Pilot wrote on 12/17/2019 10:19 AM:
On Tuesday, December 17, 2019 at 10:15:29 AM UTC-7, Jonathan St. Cloud wrote:
On Tuesday, December 17, 2019 at 8:06:29 AM UTC-8, Matt Herron Jr. wrote:
On Monday, December 16, 2019 at 4:43:23 PM UTC-8, JS wrote:
Good shocks seemed to have the biggest effect in my experience.

I have used three different model year Jeep Grand Cherokees as tow cars for
over 35 years. Nelson Funston (JN) is a tire and trailer expert with big heavy
trailers. With my first Jeep, told me to do three things in following order:
-Move some weight forward,-stiffer sidewall trailer tires at max pressure,
-vehicle tires at max pressure. Ancillary advice, maintain Jeep shocks... We
have some interstate speeds of 80 mph in Idaho. No sway!! All my Jeeps were
the 8cyl model so heavier than the old 4cyl and most currently available 6cly
on the road. Also all had 4 wheel drive and the off road accessory that has
different suspension and road clearance. Boise Pilot




Look out when moving trailer weight forward... Never exceed the maximum
tongue weight! Jim

Also tighten up the hitch in the receiver with one of these: they take out
the slop that can add to sway, and quiet down the rig

I found once I stopped towing with a Jeep Grand Cherokee I had no more sway
problems.


Anyone that wants to hear more from Nelson Funston can download his OSTIV paper on
trailer stability he

http://journals.sfu.ca/ts/index.php/...wnload/779/737


Anybody convert that model to a nice Excel spreadsheet?
 




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