Not a happy camper....crash while towing

[Glenn Baglo]

My recollection of the instructions for setting up the Prodigy P2 is that it carried a warning that when the manual lever is used to apply the brakes that the trailer brake lights will not be on so you should take care that there is nobody behind you when testing the brake controller setting.
So, maybe it was being used. If it was or wasn't, who's going prove it?

[Bob Miller]

WOW, Well I try to not jump to conclusions before all the evidence is in... I think that we call that "Innocent until proven Guilty".


But, if you need a "System" to keep the plug from falling out, it's a sure possibility that others, including moi don't have such a "System", and we just connect the plug as the manufacturer intended.


I have seen a lot happen on the road over the past 37 years of RV'ing, including seeing perfectly good parts fail without warning.


And, as you may have guessed, I'm not real big on labeling.

[Bob Miller]

Originally Posted by Glenn Baglo

My recollection of the instructions for setting up the Prodigy P2 is that it carried a warning that when the manual lever is used to apply the brakes that the trailer brake lights will not be on so you should take care that there is nobody behind you when testing the brake controller setting.
So, maybe it was being used. If it was or wasn't, who's going prove it?

I would have thought that the stop lights would have come on with the trucks service brakes that the driver surely hit before everything came apart.

Unless someone wants to dig out the Idaho State Patrol accident records, I am sure that we will never know what cause the accident.

[MC1]

Originally Posted by Bob Miller

And, as you may have guessed, I'm not real big on labeling.

[Paul O.]

Lots of new comments here, so I had to go back and see this video again. The location looks like somewhere on the high plains, on a straight and flat interstate. That is where the 18wheelers go 70 or 80 mph. Crosswinds could be 40 mph, easily. It shows clearly that the trailer oscillation really gets going just as it passes the truck. The trucks displace a lot of air and create a bow pressure wave. That trailer may have been on the verge of instability, probably for a long time. Then the moron decides to pass the big one - hello, anybody home? Maybe he did not touch the brakes because he was scared out of his wits. I would be. And that would have made things even worse.

Those bow waves created by the trucks, or the crosswinds have a much bigger effect on boxy stick built trailers than the egg-shaped that we here like so much. And in some cases even the vortex shedding from the back of the stick trailer could be enough to help drive the oscillation.

Another lesson here is about the inherent stability of the 5th wheel towing. Are there any other than Scamp and Escape in the FGRV category? When I was trying to decide what to get, I watched many videos like this one, and they helped me make up my mind pretty quickly. I wanted something easy to tow, having never done it before.

[Jon in AZ]

Bigfoot used to make several fifth wheel models. They come up in the used market occasionally.

[Bob Miller]

The Youtube clip is labeled I-86, Idaho. I-86 (Idaho) runs West from Pocatello for only 63 miles until it intersects I-84 in the southern part of the state. That's pretty flat across there.
https://en.wikipedia.org/wiki/Interstate_86_(Idaho)

The real bad news about Idaho for trailer peeps:
"Idaho has one of the highest speed limits in the United States. Only 1 state legally allows speeds faster than the Idaho maximum speed limit of 80 miles per hour."


The speed limit for towed trailers is: "The same as posted for automobiles"

[Paul O.]

The domain of "legal" and the domain of "smart" have a small overlap.

[John Linck]

Couple of thoughts.

First, amazed the stick built rv stayed together. I always expect them to unfold in these situations.

I always use a mini bungee cord to secure my seven pin connection after the cable got so stiff during zero degree towing that it unplugged itself. Not sure why the cable is so stiff even at higher temps. I considered stripping off the cable's sheath and replacing it with something more flexible, but the bungee seems to do the trick.

Cheers all, john

[Jon in AZ]

Curious, John... the cover flap on my TV's connector engages a tab on the plug to hold it in. Does yours have that? I can see it might slip off on a good bump in extreme cold, or if the spring was weak. Not that I have any plans to tow in extreme cold... for us that's anything below freezing.

[Ken C]

on RV.net..."A guy over in the TT forum (RCMAN46) who lives in the area worked out how far the markers are spaced apart. He then used this to calculate the speed of each vehicle. He calculated that the Semi was going 69.9 and the F250 was going 78."

[Bob Miller]

That about perfectly matches my experience in ID last month. Trucks tend to drive about 70 MPH and the trailer guy was just below the speed limit of 80 MPH.

[RogerDat]

Trailer stability does tend to have a relationship to speed. One thing about a trailer that is a "little" loose in the rear but manageable, it is only manageable until it suddenly ain't. That threshold can be razor thin. One more mile per hour, a few mile per hour wind gust at the wrong angle, a bit of rough pavement at the wrong time....

If you ride the edge sometimes you are going to fall off. If you don't have clue one where the edge is you either are cautious or you find it the hard way.

On the highway today found myself watching the back end of a pop up behind a good sized SUV using every bit of the lane for sway at every bump (Mich. roads so we have bumps don't you know) Me I would have been slowing down, this _____ (rookie, idiot, careless, clueless, unsafe, etc. pick as many as you want and add more) put on more speed to pass!

Back end of that trailer was to "wag the dog" and I could see the back of the SUV swaying a bit. I decided a lane over and 5 miles slower would give me more time to react. Kept it on the road but not by much and where a person aware of the danger would have needed clean undergarments, this person appeared totally oblivious. Not a Darwin award winner but certainly a up and coming contender.

Nice thing about this forum, the people that might do what that pop up driver was doing through inexperience come here, ask questions, and learn enough to not do it.

[MC1]

Originally Posted by RogerDat

On the highway today found myself watching the back end of a pop up behind a good sized SUV using every bit of the lane for sway at every bump (Mich. roads so we have bumps don't you know)

Roger, saw a similar rig not that long ago. A big Ford Excursion towing a tongue high pop up. He was going 70MPH and the pop up was wagging back and forth to beat the band. It supports the old theory that " if everything is wrong with the rig's set up a large heavy tow vehicle will help keep it on the road"......... most of the time!

[John Linck]

Originally Posted by Jon in AZ

Curious, John... the cover flap on my TV's connector engages a tab on the plug to hold it in. Does yours have that? I can see it might slip off on a good bump in extreme cold, or if the spring was weak. Not that I have any plans to tow in extreme cold... for us that's anything below freezing.

Yeah my flap was engaged. Extreme cold was the likely culprit. I asked an RV dealer for a more secure latching plug/jack and he recommended the bungee. Seems a bit of a Rube Goldberg solution to me, but it works. No problem since. Still looking for a higher quality arrangement. That cable is incredibly stiff in cold weather.

John

[Andrew Gibbens]

Originally Posted by RogerDat

Trailer stability does tend to have a relationship to speed.

I think aerodynamics play a big part in that. European wind tunnel tests on trailers (not fifth-wheels) towed behind cars showed that all lost tongue weight due to aerodynamic lift on the front of the trailer body. In effect, the faster you go, the nearer you get to a negative tongue weight with all that implies.

This is the reason that all European trailers - being in Europe they are expected to be towed with hitch weights that are low by US standards - have sloping fronts as that was found to largely counteract the aerodynamic lift at speed and so avoid negative hitch weights.

What is interesting is how they get record-breaking trailers to remain stable at very high speeds, 140mph or so. Admittedly the record is currently held by a GMC 2500 towing a 2,700lb trailer so that ratio of tug to trailer must help.

[steelypip]

Originally Posted by RogerDat

Trailer stability does tend to have a relationship to speed. One thing about a trailer that is a "little" loose in the rear but manageable, it is only manageable until it suddenly ain't. That threshold can be razor thin. One more mile per hour, a few mile per hour wind gust at the wrong angle, a bit of rough pavement at the wrong time....

If you ride the edge sometimes you are going to fall off. If you don't have clue one where the edge is you either are cautious or you find it the hard way.

This.

Every time I've towed a combination that tried to come unglued at some point, it had a critical speed at which it tried it. 5 MPH below that speed and everything was fine.

Note that this is after I've looked at things like proportion of tongue weight and tow vehicle loading as part of the combination setup before pulling out.

I've taken to testing that behavior on purpose (better the devil you know): I'll take a new combination (say an unusual load package on my one axle utility trailer) up to a speed I am just about positive is safe, say 35 MPH, and then I'll jink the tow vehicle like I was avoiding a road hazard. If everything tracks nicely, then I'll repeat the operation at 45 MPH. If I'm going a good ways and need to make the best time, I'll repeat it again at 55 MPH. The goal is to set up an oscillation on purpose to see if you can get one.

At some speed, the combination will start to talk back - the inertia of the trailer in combination with tire tuck, aerodynamics, spring squat...all that stuff will cause it it try to start the combination oscillating, generally noted by a distinct cyclic back-and-forth pull on the steering wheel and the rear end of the TV trying to sway to and fro. If you catch it below the critical speed, it will self damp in one cycle or so, especially with a little help from trailer brakes or just holding the wheel steady.

That wiggle is your hint that you probably don't want to go a whole lot faster than that. It might be 40 MPH on a 'close to the edge' combination. Or it might be faster than you care to go anyway (my utility trailer when empty tracks behind the car perfectly - I'm sure it has some critical speed, but it's well above any I care about).

If you've found the critical speed and you drive below it, you know that you will be able to avoid an asphalt alligator or be passed by a big truck without ending up sideways in a ditch, because you've already demonstrated that the combination is safe below that speed.

The tricky part is that the slope of the oscillation curve is quite steep - you can go from 'that is a little wiggly' to 'very scary' in about 3 MPH of road speed - which means that going downhill can get excessively exciting if you're not aggressive with the brakes. It's worth finding out where 'wiggly' is before you're surprised by it.

The day I brought my Casita home, I performed this test on it, which resulted in cushions on the trailer floor and some open cabinet doors among other things. The good news is that it tracks very well behind my TV and I really don't have any stability concerns with the combination up to any practical speed (and no, I don't regard 80 MPH as a practical towing speed).

As we perfect our loadout, I'll retest to verify that we haven't done something weird. I suspect we won't have, as I have already schooled my spouse in the importance of low and forward for heavy things, and in the TV best of all if it's heavy.

[David Tilston]

I was travelling at about 100 km/hr, (62 miles/hr) at night, pulling my 4500 on the way to the west coast along the number 3 highway. As I came across a narrow bridge I saw something in the road, just after the end of the bridge. It was a deer laying down, and facing away from me. It's head was up, so I can only conclude that it was bedding down while enjoying the residual heat in the asphalt. I was completely aware that I was pulling a trailer, but choose to do an emergency swerve, hopping that I would be able to control the resulting trailer sway, after I missed the deer. There was no sway, not even a wiggle. I had packed carefully and I had 10% of the weight on the tongue. But still, I expected some trouble.

I think the fact that I tow with a van helps my towing stability. The front of the trailer is in the wind shadow of the van. No Karman vortex street to initiate sway. The most stable place is directly behind the van.

On that trip we did however experience sway:
http://www.fiberglassrv.com/forums/f...eel-53227.html

[Uplander]

Sometimes all you need is a bungee....or perhaps a bit of DUK Tape.

*hit happens ! Don't let it happen to you.

[Bob Miller]

Originally Posted by Andrew Gibbens

I think aerodynamics play a big part in that. European wind tunnel tests on trailers (not fifth-wheels) towed behind cars showed that all lost tongue weight due to aerodynamic lift on the front of the trailer body. In effect, the faster you go, the nearer you get to a negative tongue weight with all that implies.

This is the reason that all European trailers - being in Europe they are expected to be towed with hitch weights that are low by US standards - have sloping fronts as that was found to largely counteract the aerodynamic lift at speed and so avoid negative hitch weights.

What is interesting is how they get record-breaking trailers to remain stable at very high speeds, 140mph or so. Admittedly the record is currently held by a GMC 2500 towing a 2,700lb trailer so that ratio of tug to trailer must help.

As mentioned earlier, Most countries have a lower speed limit for towing than the U.S. meaning that they can have lower hitch weight ratios. I think that we all know that if something is going to happen that it's usually above 55MPH when it does.....