Help me choose a trailer

[slowmover]

Along with low ground clearance I'd also want independent suspension and disc brakes all around. ( And MAXBRAKE controller). And enclosed undercarriage. I-S is worth every penny or trouble. Please add an exhaust brake if a diesel.

I see you have an interior height requirement. And one of square footage. Can it brought to a cubic foot requirement instead? While 6'-W is great, 6.6' tall is not. Anything to reduce frontal area is the thought. I'd rather have longer than taller.

The other "requirement", IMO, is a significant side radius where roof and walls meet. Side winds become "trapped" against a squared wall and this is a safety performance item as radiused curves allow wind to spill over. The longer the trailer, the higher the forces acting from FF/RR while at speed.

Videos of rollovers (big truck and smaller;

straight truck

and

RV

) reveal this quite well: the rear of the vehicle lifts first.

The State of Wyoming even has a 2007 White Paper ("safety study") showing calculations about wind speed versus blowover for various types (a fifth wheel travel trailer is in trouble with about 35-mph crosswinds, a conventional trailer at about 50-mph). As you're running 3k weekly I take it you may have been a truck driver: much of the above is in reference to IH80 near Elk Mountain in winter.

Height is a problem, followed by length, but ameliorated by radiused side walls. The roll center improvement of independent suspension, and radiused walls, is not accounted for in the above study.

Silver Streak Travel Trailers used a 22" radius; Airstream one that was almost continuous (through the 1970s'). The winds just roll off.

I've scanned around the sites of various builders of enclosed cargo trailers in vain concerning side radius.

On the Pirate 4x4 site are quite a few "builds" using enclosed trailers of the type under discussion for combo living/4-whlr. And, of goosenecks with "campers" installed to also have rear space for a 4WD on the rear. (See "Mobile Marriott" for some great fab skills). Here's an Airstream-on-gooseneck build that terminated early, but some good stuff shown in re this discussion. See the pics of aero fifth wheels I posted there at end.

As a note, I've generally seen no GN or 5'er where the ground clearance as low as a conventional (with a few exceptions) This a road performance problem. Alternatively, a 10k max trailer one can utilize a PULLRITE conventional hitch that is functionally identical to a GN. Aero may be much easier as a result if Q's of ground clearance and pickup bed utilization are paramount. Compare height measurements and calculate COG height on all trailers, IMO.

.

[slowmover]

Meant to include this: Radius

[wyatt]

Originally Posted by slowmover

Meant to include this: Radius

Just so you are aware, the picture in the link is talking frontal radiusing, not radiusing on the wall/ceiling or wall/floor. Although these are likely beneficial radii, and I am sure I could look in my Hucho book and find something, that's not what is being shown. (you likely already knew this, but it may help someone else)

[slowmover]

Originally Posted by wyatt

Just so you are aware, the picture in the link is talking frontal radiusing, not radiusing on the wall/ceiling or wall/floor. Although these are likely beneficial radii, and I am sure I could look in my Hucho book and find something, that's not what is being shown. (you likely already knew this, but it may help someone else)

Yes, thanks, and it does apply to heavy crosswinds with only a smidgen of imagination, however imperfectly.

[KamperBob]

Originally Posted by wyatt

Just so you are aware, the picture in the link is talking frontal radiusing, not radiusing on the wall/ceiling or wall/floor. Although these are likely beneficial radii, and I am sure I could look in my Hucho book and find something, that's not what is being shown. (you likely already knew this, but it may help someone else)

I'd love to get my hands on Waters' original paper. If anyone has the means to track it down the reference [4.80 in Hucho 4th Ed] said Waters, D. M., "The Aerodynamic Behavior of Car-Caravan Combinations," Paper 4, Proc. of the 1st Symp. on Road Vehicle Aerodynamics, London, 1969.

The solid curve seems like his empirical work with the dash curve for reference. In the English translated version of Hucho 4e (which I borrowed a few ago months via public inter library loan but had to return ) the note over the dash curve said "Rectangular bock, all corners radiused."

We all know that rectangular boxes have 12 edges. What I'd love to fully understand is exactly which of those edges were meant by Waters in both the solid and dash curves. The stark difference in shape and scale between the two may be intuitively suggestive. Tracing it to the horse's mouth would be awesome!

[skyking]

from the original post, Aerohead deduced that the solid line represented a rectangular box with the front edges only radiused.
The dashed line represents all corners radiused.

[slowmover]

As said, I haven't seen any cargo trailers with radiused edges (of enough curvature), but with so many miles in so short a time (3k miles x 50 weeks) there will be adverse weather and traffic conditions unavoidably, thus my emphasis. Two of the worst:

1] On a mountain downgrade being overtaken/passed by an 18-wheeler.

2] On a narrow two-laner being passed in the opposite direction by a pair 18-wheelers close together (which is illegal, by the way; this is well-understood) which causes the 70+ mph bow waves to hit and reverse direction violently, in less than a second, multiple times. The complications engendered by the bow wave of the tow vehicle and of the trailer and that they are being hit by different forces at the same time.

Good aero means more than mpg in situations like the above. These two are perhaps the worst situations where even the best hitch rigging from the best tow vehicle and trailer avail a little more edge to the driver prior to a loss-of-control accident (as with wind shear in the earlier post.)

An aero trailer with independent suspension and disc brakes with state-of-the-art brake controller is the gold standard.

The latest OEM brake controllers use a combination of vehicle stability control and anti-roll braking forces. What is missing from the OEM brake controller electronics at this point is Anti-Lock trailer brakes.

Thus I would also consider the Antilock module in concert with the offerings of DirecLink (please request a copy of their free brochure, an excellent overview of braking systems; whether you are experienced or novice) but have no reviews at present of it's performance.

Substantially radiused edges (subject to data) are important as are clean entry/exits for a trailer.

In all of the above, the least input by the driver to maintaining lane-centeredness in all conditions is also central to higher FE. Steering control.

The trailer that imparts the least force against the steering of the tow vehicle is "safer" (subject to definition), and is easily better for FE.

.

[slowmover]

Montrose Trailer; Pics #30 & 31 of 78; Low Profile Auto

Pretty well the closest thing I found to an "aero" enclosed trailer (as said, non-radiused edges).

[wyatt]

Originally Posted by slowmover

Montrose Trailer; Pics #30 & 31 of 78; Low Profile Auto

It looks like that trailer should be aerodynamic, but since the back is sloped at about 30 degrees, it couldn't be worse! 15 degrees is what you are shooting for, 30 degrees is the worst you can do (increases drag dramatically), 0 and 45+ are the same.

[slowmover]

I was looking for enclosed cargo trailers, for sale.