Quote:
Originally Posted by sregord
OK Lets step back a couple, please.
The "Stemco-trailertail" which the drivers didn't like...doesn't seem to be on the market anymore. "They're compromised because their perimeter isn't airtight".
You referring to where the the trailerTail attaches to the corner of the trailer? correct?. as the Mercedes Benz trailer"tail" is open, and Betterflow
has another european foldaway that is open ended. Both "compromises" to ease driver PITA issues. |
I might have 'tightened' my language! Sorry.
It is the 'attachment' perimeter of the Trailer-Tail which compromised its performance.
As an 'angled' box-cavity, the 'loose' fit to the trailer van allows turbulence to contaminate the pressure rise potential of the elongation.
If you'll examine United States Patent Number 4,682,808, by Bilanin, you'll see that a 'proper' box cavity has an 'airtight' connection to the trailer's rear.
Zero porosity.
It's okay to be 'open' at the rear, but not the top, sides, or bottom. The 'leakage' destroys some of the pressure recovery, the whole idea for elongation.
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The very last iteration of the Betterflow semi is what you want, for what's presented.
They're using the full height of the trailer (minus ground clearance ) for streamlining, and their boat-tailed cavity fits snugly against the trailer van, perfectly protecting the pressure rise.
It's almost as good as Renault's, 1987, V.I.R.A.G.E.S. concept semi-trailer, Cd 0.298 ( with 29.5", 5-degree boat-tail, and fully-enclosed wheels ), SAE Paper 870714, Figure 6.
I do take issue with the central, 'catamaran' ducting. Solar race teams have discovered the catamaran design to have the highest drag. And it precludes the lowering of the height of the cargo floor, which terrifically impacts frontal area, center-of-gravity, and propensity for rollover / blow-over, while running dead-headed.
Having had a Class-A drivers license, I've always struggled with the wisdom of placing cargo four feet above ground level. School buses especially!
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PITA to the driver seems to be a real issue within the industry.
( I'd just fully-professionalize driving, pay them all a salary, and remove the gun-to-the-head, ticking- clock anxiety over load-in/off-load time vs daily mileage ).