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Old 12-10-2013, 07:36 PM   #57
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I get what you are driving at but it is not an either/or question, more of a gradient. 100% stable @ 10% tongue weight to 0 stability @ 0 tongue weight to negative (completely unstable) @ negative tongue weight.

You have to experience it. I suggest you get a SMALL trailer, like a luggage trailer, and experiment with cement blocks or other movable load. If you go to a 0 or negative tongue weight you may be surprised how that little trailer can whip your tow vehicle back and forth. DO NOT DO THIS ON A PUBLIC ROAD.

Once you have done this you will appreciate having enough tongue weight. Since it is easy to get and costs nothing, might as well have plenty which is 10% of the trailer weight.

British and European trailers (caravans) seem to be stable with quite low tongue weights by our standards. I'm not sure how they manage it except their caravans are light and are limited to quite low speeds.
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Old 12-10-2013, 08:07 PM   #58
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I think some of this equation is the importance of keeping the center of mass of the trailer forward of its center of gravity. (think: badminton birdie---heavy end goes forward). Its really hard to know where either of those things is, exactly...but you can easily know the weight of the vehicle, and the tongue weight; 10-15% insures a forward center of mass.
(may be totally wrong, but it seems like that might be the source of the rule-of-thumb, here).

My old vw bus really wanted to be going the other way. (back-end first!). And it would do just that, very easily, on a snow covered road.
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Old 12-10-2013, 08:09 PM   #59
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Originally Posted by Ganaraska View Post
are limited to quite low speeds.
Same as most anywhere here, 100km/h or 60mph. Most people seem to tow at around 110-120km/h.
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Old 12-10-2013, 08:20 PM   #60
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The ProPride that I had weighed 220lbs., but they have been proven stronger than the Hensley.
Please share that documentation.
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Old 12-10-2013, 08:21 PM   #61
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There are other factors involved. Going down hill or braking will increase instability. Side winds can be a problem. Damping or lack of same in the suspension. Airstream addresses all these. Tongue weight is an important factor but not the only one.

There are those who believe a big heavy tow vehicle with a long wheelbase is automatically the best tow vehicle. Take a look at this video.

An RV crash to remember - YouTube

Road dead straight and smooth, speed moderate, tow vehicle a long wheelbase 1 ton dually pickup. The problem appears to be the side wind.

I don't see any spring bars or sway control. Who needs them when you have a BIG tow vehicle, right?

I suggest an Airstream towed by a Chrysler 300 properly set up would have experienced no distress.
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Old 12-10-2013, 08:24 PM   #62
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This instance is an example of a negative feedback loop. Notice how the sway gets worse and worse. Typical of not enough tongue weight, down hill, or braking situation.

www.DangerousTrailers.org Presents Stolen Boat Trailer.. Trailer Sway - YouTube

Appears to be trying to stop on a down grade without trailer brakes or weight distributing hitch.

Do you really want to cut your tongue weight and stability to a minimum and cross your fingers?
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Old 12-10-2013, 08:30 PM   #63
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I think some of this equation is the importance of keeping the center of mass of the trailer forward of its center of gravity.
.
That's not what the Baily demo shows, however. They want the weight right on the axis of yaw. The reason is that all weight at a distance from the yaw axis, creates high inertia when any side force is applied. That's what the sway issue is all about. A side force is applied to a mass that is at a distance from the yaw axis, and off you go with sway. The forward speed of the TV whips the force back in the opposite direction increasing the inertia in the other directions. That's instability.

Imagine moving the trailer axle forward, creating a very long tail. I think your intuition will tell you this is unstable. Not because of a loss of tongue weight, but because the mass x distance behind the axle becomes very large. Now imagine moving the axle way back. That farther back you move it, the harder it is to imagine it will sway. This is because there will be no mass x distance to be affected by a side force behind the axle.

So, one hypothesis is that tongue weight is simply the necessary (evil) result of moving the axle far enough back to limit the mass x distance that a side force can work upon.
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Old 12-10-2013, 08:34 PM   #64
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Do you really want to cut your tongue weight and stability to a minimum and cross your fingers?
Of course not. That would be silly. I want to make it as small as it can be within the stability margins of my setup. As I said many times, I think an arbitrarily high number is selected in order to cover all possible conditions. I want to tune it my circumstance if possible. In a word, I want to "optimize."
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Old 12-10-2013, 08:52 PM   #65
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Are we having fun yet?.....


Why not let the trailer tell you....
http://www.wimp.com/talkingboat/
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Old 12-10-2013, 09:00 PM   #66
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Are we having fun yet?.....

Why not let the trailer tell you....
http://www.wimp.com/talkingboat/
Bob
Ok Bob - 'fess up....did you record that from your truck following that boat?!?! :-D
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Old 12-10-2013, 09:11 PM   #67
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Please share that documentation.
It's all in this thread: http://www.airforums.com/forums/f464...ley-94432.html
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Old 12-10-2013, 09:39 PM   #68
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Of course not. That would be silly. I want to make it as small as it can be within the stability margins of my setup. As I said many times, I think an arbitrarily high number is selected in order to cover all possible conditions. I want to tune it my circumstance if possible. In a word, I want to "optimize."
What do you expect to gain by having less tongue weight?
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Old 12-10-2013, 09:46 PM   #69
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All's fair in hitch's and war...

Those PP's are junk just like the haha's.

"If your happy with what you're using......it's adequate.

If others are unhappy with what you're using......it's not."

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Old 12-10-2013, 09:49 PM   #70
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What do you expect to gain by having less tongue weight?
Here's what I said way back in post #5: "My purpose for questioning tongue weight is that I am setting up my new TV, a Chrysler 300 S. I will be towing my 2012 Flying Cloud 25. As this is a sedan, I need to budget my payload carefully. I will only have about 1200 pounds to play with. If I could take 100 pounds off the tongue, FOR EXAMPLE, that would be a significant improvement in my payload budget. "
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