Pulling A Fifth Wheel vs. Bumper Pull

rhagfo wrote:


Ity is what you left out in your physics, the fact that with a TT the force of the trailer is applied 3' to 4' behind the TV rear axle, where with a 5er it is applied at the axle zero leverage on the direction of the TV.

Fuel mileage, well many that have switch from TT to 5er with same TV, report either no change or improvement in fuel mileage, with a heaver trailer. This is likely has to do with better overall aerodynamics, yes a 5er is taller, but the front is closer to the TV cab than with a TT.

For the first point it was not mentioned as it's not relevant to stability, which is the subject. While yes the TT will provide some longitudinal attempt at rotation that the 5th wheel won't see it is only a small fraction of a much smaller force with the TT. It will feed back through the steering and some may interpret this as less stability it is in fact not reflective of what may put the trailer on its shiny side for any proper setup. If this is a perceived problem you can buy hitches like the Hensley hitch which moves the effective pivot point even farther forward than the fifth wheel pivot point is. Mine I calculate at almost a foot in front of the rear axle, as opposed to an inch for a fifth wheel.
There are people who slalom race trailers, some for fun and some to test hitch setups. As with car racing lower is more stable, indeed I notice some don't even allow/try fifth wheels as while a TT can get it's wheel in the air and still recover, good luck with that and a fifth wheel. And thats without wind.
For the second point even an extremely aerodynamic trailer like the Airstream only reduces the barn door like drag by 20%. Those extra 3 extra feet or whatever of a fifth wheel are adding far more drag than that, so I'll put this one in the brand loyalty category till I see a controlled environment measurement that shows that better fuel economy. It's like my dad who always claimed 20 mpg with his 74 Newport, I never saw anything that like that when I measured it when I got it.
Over half of the aerodynamic improvement of the Airstream is from the *backend* shape, I haven't noticed many 5th wheels with any attempt at fixing that backend turbulence. Do you have an example of one with a streamlined backend other than slowly lowering the roof, because you need that you have any chance to support your assumption of less drag.
I think there is a lot of 'brand loyalty' going on here....