Tractor-Trailer: Skirting vs belly pan

[KWTrucker]

Greetings, I drive KW T600 with Step Deck trailer. Finally got storage boxes hung all down both sides of the trailer which gives me storage and provides sort of a smooth surface for air flow. They hang (literally) from the trailer so they can float if/when I get the trailer hi-centered. They are 14" off the ground at the moment. I was going to lower them slightly and try to add flexible skirting along the bottom, but am reconsidering simply installing belly pan between the boxes down the center of the trailer. There seems to be a "lower is better" mantra, and the reading I have done shows a linear relationship between height of skirting and effect/result. What about belly pan? Is lower still better? What are the opinions/issues I should take into consideration. Both skirting and belly pan have similar challenges if terms of maintenance, weight, etc. I am well aware of the non-intuitive nature of aerodynamics, and one alternative (it won't work on my style of trailer) which I think has merrit is shown here: SmartTruck. Recent mpg from Baltimore to Orlando w/ tailwind: 10.1 mpg. Best to all

[slowmover]

10-mpg . . man, I think I'd feel that way if my Cummins-Ram hit 40-mpg. Congratulations! I only ever saw that was bobtailing or with a small block Detroit with an empty flat at a long drive at 55-mph . . on the flats with a tailwind, ha!

There is interest here on Class 8, but mainly from non-drivers. There a re few threads where stuff has been thrown out as information. To the best of my knowledge, outside of the Europeans, much is guess and go by O/O's on these subjects.

As to "non-intuitive" think about crosswinds from all directions. (And access for maintenance).

One contributor here -- Big Dave, a former train driver -- has used rip-stop, highly reinforced conveyor belting for an airdam on his F350. Said to be unfazed by curbs and speed humps.

Pictures of your rig would spark ideas, especially profiles front, rear and sides (and underside) of the trailer.

As a side-note, have you been reading DICE1 and his "10-mpg . . . " thread on Truckers Report?

Edit: I see that there was no response to your earlier, similar thread here.

But some pics and responses, here.

If I might suggest it, keeping track of one vehicle through one thread makes for easier continuity for readers.

.

[KWTrucker]

Thanks Slow Mover. I will try for some pictures. I have more ambitions than time. Time to do much is a factor also. I'll keep working away at it though.

[aerohead]

Originally Posted by KWTrucker

Greetings, I drive KW T600 with Step Deck trailer. Finally got storage boxes hung all down both sides of the trailer which gives me storage and provides sort of a smooth surface for air flow. They hang (literally) from the trailer so they can float if/when I get the trailer hi-centered. They are 14" off the ground at the moment. I was going to lower them slightly and try to add flexible skirting along the bottom, but am reconsidering simply installing belly pan between the boxes down the center of the trailer. There seems to be a "lower is better" mantra, and the reading I have done shows a linear relationship between height of skirting and effect/result. What about belly pan? Is lower still better? What are the opinions/issues I should take into consideration. Both skirting and belly pan have similar challenges if terms of maintenance, weight, etc. I am well aware of the non-intuitive nature of aerodynamics, and one alternative (it won't work on my style of trailer) which I think has merrit is shown here: SmartTruck. Recent mpg from Baltimore to Orlando w/ tailwind: 10.1 mpg. Best to all

The height above ground level is going to be determined by ground clearance requirements,say,when driving over the crown of a railroad track crossing.
The skirts are attempting to provide a flow support surface at the width of the outer tire/wheel face,just like a Trans Am Firebird of the 1980s.
The bellypan is attempting to prevent air from entering the torture-chamber under the tractor/trailer.
Bellypans need to begin at the front,and proceed rearwards for good effect.
If you pan the trailer without doing the tractor,there is every indication from wind tunnel studies,that you'll go un-rewarded.
The 10 mpg is a glimpse of what streamlining will do on a 'calm' day.The Renault V.I.R.A.G.E. of the 1980s was claiming 10 mpg.GOOGLE that rig and check out what was done there.

[spacer]

R.R. tracks were the first thing to come to mind for me. My old Pete 372, if I did my part and with a moderate load/relatively flat route, I could manage 9 fairly well. That was without much in the way of intentional technique or anything.

Heck, I've seen a couple from time to time for sale, though I sold mine due to parts availability issues, I'm still tempted to grab one, fix it up some, and use it for local intermodal runs or the like.