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Topic ClosedHave you weighed your 180?

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Colt View Drop Down
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Direct Link To This Post Topic: Have you weighed your 180?
    Posted: 27 May 2020 at 9:55pm
Yes. So you might want to shift some cargo forward to keep the C.G. forward of the axle.

Why doesn't Forrest River publish a weight and balance sheet to make calcs like this easier? Sure, I can build my own, but you know the engineers build one as part of the original design.
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Direct Link To This Post Posted: 28 May 2020 at 5:04am
Yep, works in reverse Jato just like you're sayin'. One wrinkle though, the axle has to take any additional load not taken up by the tongue so when you add load aft of the axle, causing the tongue weight to go down, the axle load goes up faster than the load. The same is true of load in the back of the tow vehicle. In both cases adding load forward of the respective axles is almost always better. 

Colt, I bet you can already answer your own question about FR providing a weight & balance sheet. Three little words; "avoidance of liability". You can't give someone a tool (W&B sheet, schematic, or hydraulic jack) and tell them to have at it, at least not without either assuring folks are trained in the proper use of the tool or have waived any claim to damages from improper use. It doesn't help them sell more trailers and it could cost them a bunch of legal fees, so why do it? Sigh...
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Direct Link To This Post Posted: 28 May 2020 at 8:34am
It would be easier to make a legal case against FR for the failure to provide a weight and balance sheet than to make one against them for someone who didn't follow the instructions using one.  It's isn't that hard to write adequate disclaimers on a weight and balance sheet.  A job for a first year law student.

Just like their use of a generic "owners manual" for most of their trailer lines, it's really a matter on not wanting to incur the cost of writing trailer specific materials.  
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Direct Link To This Post Posted: 28 May 2020 at 8:59am
Originally posted by lostagain

It would be easier to make a legal case against FR for the failure to provide a weight and balance sheet than to make one against them for someone who didn't follow the instructions using one.  It's isn't that hard to write adequate disclaimers on a weight and balance sheet.  A job for a first year law student.

Just like their use of a generic "owners manual" for most of their trailer lines, it's really a matter on not wanting to incur the cost of writing trailer specific materials.  

I knew I'd get a response on that one.Tongue

It doesn't work the way you suggest in practice, or maybe in a way it does. In manufacturing companies I've worked for there are always staff engineers who could easily write the instructions so that was budgeted, but not staff attorneys who could vet them and write the disclaimers. That would have cost additional unbudgeted $$. So documents requiring legal review and input never happened unless they were essential for sales of the products.  And specific materials were always discouraged due to the risk that they would not be maintained properly and result negligence claims.

In aviation, W&B worksheets are essential to keep the pilot and their passengers alive, so they are done as a matter of course. The customers are pilots who have been trained in the use of these materials and tested and licensed by the FAA certifying that they know how to do so. Not so with RV owners, the vast majority of whom wouldn't have the faintest idea what a W&B sheet was for. 

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Direct Link To This Post Posted: 28 May 2020 at 9:21am
I think I've had a little more experience in practicing law (since 1973).  If companies don't want to pay lawyers to review, and often translate from engineerese to legalese (two incomprehensible languages for normal humans) then they're cheap.  It's not because of fear of suits.  


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Direct Link To This Post Posted: 28 May 2020 at 10:08am
And I have more experience in product engineering (which is what a W&B spreadsheet is after all), since 1978. All companies are "cheap", probably none spend what the really should on either engineering or legal resources. Call the motivation "fear of litigation" or "wanting to do the right thing", companies have to decide where to apply their limited resources and where not to. 

Going back to Colt's original comment, my point is that just because the FR engineers have a W&B spreadsheet that they use when designing their trailers doesn't mean that that can be provided for external use by customers without a substantial outlay of additional engineering and legal resources. And to what end? A W&B sheet is not either expected by trailer customers or customary in the RV industry. Better not to do it at all, as I'm quite certain both their head of engineering and their chief counsel would advise. 
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Direct Link To This Post Posted: 28 May 2020 at 10:18am
OG, don't try to practice law.  You're a great engineer, but a lawyer not.

There is no reason not to give a W&B work sheet, except cost.  It has nothing to do with legal liability or lawyers.  
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Direct Link To This Post Posted: 28 May 2020 at 11:28am
lostagain, don't try to practice engineering. You're a great lawyer but an engineer, not. 

Like most non-engineers, you are underestimating what would be required to do the job of properly releasing a W&B worksheet in a way that doesn't put the company at risk. The FAA's handbook for aeronautical engineers on W&B is 114 pages. The airman's knowledge handbook that all pilots are trained and tested on has a half dozen pages on the topic, and in pilot training you spend a whole 2 hour session on it usually. A typical POH (pilot's operating handbook) for a small aircraft devotes 10-12 pages to the topic. Trailers would likely be more complicated, because the loading scenarios for a trailer are a lot more complicated than for a small airplane. The safe operating envelopes are a lot more complex too, because there is a second vehicle involved. 

So, you can call a trailer manufacturing company not wanting to incur all that cost "cheap" but why would it when no one expects it to do so? If the company just provided anyone who asked their engineering W&B worksheet, without all the training and accompanying documentation, change control procedures whenever the design of each trailer changed, etc, someone would misuse the tool, a death or injury would occur, and the company would be subject to a lawsuit. 

Is a lawsuit justified in that case? I think almost certainly yes, because surely the company has a duty to try to assure that the parties that it gave access to the tool were capable of using it properly. That's relatively easy when its a trained in-house engineer who has a supervisor and there are review and test procedures for every new trailer design. Not so for the general public. Its more like giving a chain saw to a 10 year old, pointing him at a tree and saying have at it. But that's just my observation, now we are in your area of expertise, not mine, so I will be interested in your thoughts on that. 

 
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Direct Link To This Post Posted: 28 May 2020 at 11:43am
I fully agree, I am not an engineer.  Plus my belief in magic, perpetual motion, and anti-gravity devices automatically disqualifies me.  

As for W&B, a trailer's balance is not likely to be as complex as an aircraft, but I could be wrong.  The Zen of W&B has worked quite nicely for me and our TT.

The failure to give adequate product use instructions, such as how to balance your trailer, is more fertile ground for product liability suits than would be a simple chart to figure out where the heavy stuff should go..  You are mixing the complexity of aeronautical physics with a simple travel trailer that usually only moves in 2 dimensions and is generally connected to the ground.  Why make things needlessly complex?  The Zen of trailer balance works just dandy, until it doesn't.
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Direct Link To This Post Posted: 28 May 2020 at 12:38pm
Maybe we should emerge from retirement and seek out plaintiffs who have gone off the road from not having their trailer loading right. You can litigate and I'll be your expert witness. I only want $500 per hourBig smile

Nope, actually light aircraft W&B is only done in one longitudinal dimension. Same as for a trailer. And there are only typically 4 "stations" that change: front seat pax, rear seat pax, luggage, and fuel.  With a trailer there are a whole lot more things that move around, not counting the mods ppl do (if those get done on an aircraft an A&P mechanic has to do them and sign off on them and recalc the W&B). So really light airplanes are relatively simple.

But I think you've hit the proverbial nail on the head. Most of the time, the zen approach to trailer w&b works just fine, and ppl don't die. Lots of pilots use the zen approach too, but the difference is that generally you don't die if you mess up your trailer W&B. It has happened though, no doubt. So it will come back to what is reasonable and customary in the industry, right? If you screw up your zen in the trailer that's on you at this point, there is no case law putting it on the manufacturer (until you get your specialized practice going and call me as a witness anyway). 

If you screw it up in your airplane, that's on you too, unless Cessna screwed it up, and they didn't, and besides, you were trained, and Cessna knows you were trained. If FR published a w&b worksheet and screwed it up, or didn't make sure you knew how to use it, they have now changed what is reasonable and customary in the industry, right? Not to mention creating a reason for ppl to be afraid to buy trailers....Not in their best interest.....

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