Fifth wheel trailer hurricane in truck bed

[Snowman9000]

Here is the way one maker attacked the issue of fiver aerodyamics. They extended the upper body in a second step, almost above the cab of the truck. The company went out of business during the economic bust, though.

[Snowman9000]

And here is my rig.

[skyking]

Nice rig, Snowman. I have some very hefty stake pockets in my bed system, 2x2x0.250 wall steel. I will build a headache rack off of those that will stay in the truck permanently.
The top horizontal member will be right at the top window gasket a couple of inches below cab top, so it won't obscure the 3rd brake light. It will have fittings on top of that to bolt on my aero cap, and any trailer fairings I make.

[Ladogaboy]

Originally Posted by Snowman9000

Here is the way one maker attacked the issue of fiver aerodyamics. They extended the upper body in a second step, almost above the cab of the truck. The company went out of business during the economic bust, though.

With this one, I'd dare say that you'd still want one of those deflector top hats that are used on many semis.



Heck, might even work on your current setup if extended.

[Frank Lee]

As far as tailgates: either stock tailgate up or no gate at all. Airgates = high drag.

[slowmover]

A 5'er tends to be quite wide. That's a wall pushing aside a lot of air. In a head-on view these things can just dwarf the truck (big fish pursuing little fish, mouth wide open).

There have been some custom hauler beds which appear to take advantage of the "gap" for storage and best clearances. But the cost is prohibitive and the simple utility of the pickup is lost.

Aerohead's archaeology diggings brought up a trailer nose from 1982: fabric, inflatable (Fibrelock; search Pop Sci 1982). Something like that could both fill the gap and ideally not damage either vehicle if it had a little give (for the rare times interference occurred with an otherwise optimized design).

[aerohead]

Originally Posted by Snowman9000

What to make of the fact that when towing a fifth wheel travel trailer, with the tailgate installed, anything in the truck bed that is light enough to be picked up by a person can be picked up by the air flow in the bed? Most fifth wheel owners find this out the hard way on their first trip.

This must be a bad thing aero-wise?

Some people pull fivers with no tailgate, and some with a vented tailgate. I haven't tried either. If I do, and the hurricane disappears, does this mean anything from an aero point of view?

What if the hitch could just emerge from a bed cover, would the bed cover reduce drag? For instance, imagine a modified gooseneck hitch arrangement, in place of a fifth wheel hitch, where the ball is at the top of a bed cover. If it could be mechanically sound, do you think it would reduce drag?

I'm not knowledgeable enough to properly address your drag question but my instinct would be to run with the gate up,to allow for the locked-vortex inside the bed.
Comparing a conventional,non-sleeper tractor to a C.O.E. tractor,the C.O.E.tractor has 15% lower drag simply because it's height is equal to the trailer height.
For both types of tractors,a 31.25" gap between tractor/trailer adds another 19% drag.
So anything which can fill in and blend these interfaces should show at the pump.
As far as raising the hitch point in order to run a bed cover.I think that it would negatively impact the center of gravity and how the rig would handle in emergency maneuvers when dodging Ken and Barbie.