This is for guys pushing 18 wheelers down those long, long roads; the guys that bring the food to your plate and all the other goodies of life.
For many years this architect has pondered the aerodynamic forces acting on those big boxes being shoved thru the air. As you may know, a box has some 14 times the aero-drag that an equal cross sectional fish shape has. This is why you see aeroshells going up on more and more cabs, to ease the airflow over the top of the box, approximating the ideal fish shape.
But that's a passive answer to wave drag losses on a 9'wide, 14' high, 35' long box, is there a better solution? There could be. Think of the box as living in the drag half of a half wavelength, Compressive stress acting on the front, and Tensile stress on the back. Basically the front is snowplowing air to the sides, and being PUSHED back; and because the box blows a HOLE through the air, the low pressure tensile stress PULLS the box back, because that HOLE has to be backfilled.
Thus the dust that piles up on your back doors is a result of that tensile stress. Now consider a light cessna airplane taxiing down a runway, only its propeller is moving it. As a thrusting element the spinning blade has low pressure on the front surface and high pressure on the back surface.
You see then where this is going? How can we apply the THRUST concept to the semitruck box? Instead of C-front/T-back drag, we have T-front/C-back THRUST just like the airplane blade/propeller. A proposed solution: 3 rows of propellers in the plane of the sides/top on the front edges and another 3 rows on the back 3 edges. They are SIDEWAYS, not longitudinal axis like the airplane propeller. The purpose is to PULL air off the front plate and PUSH it in on the back doors, creating a T/C pressure imbalance, ie, aeroTHRUST instead of aeroDRAG.
Ok then, how much energy are we talking about? Basic calc : level, straight freeway lane at 70 mph. 70 mph = 102 fps, 9'x14' cross sectional area = 126 sf x 102 = 12,935 cf. Air weighs .0807 #/cf = 1043#/sec that you have to pull sideways in the front(to the sides and top)to create a tensile stress region on the front panel.
But it's W=mg, it's not WEIGHT that matters here, it's the air MASS that's being pulled backward out in front. Thus 1043/32.17 = about 32 poundals-mass. Then WORK = Force acting through an average distance(W=Fxs). Since F=ma we have 32 poundals and a=51 f/s x 51' to the centroid of the air-mass. That's 83,232'-#-s, then divide by 550 '-#/s for 1 HP = 151.3 HP.
Now you see why you need a 350 HP diesel motor to plow/pull your way through the air? 150 HP in front + 150 HP in back = 300 HP. The question then becomes : could you improve things a bit by just backfilling the rear region with 3 rows of propellers and an electric generator running their motors?
They would be retrofit panels/rows on the back 3 edges like wings IN the plane(s)of the sides/top. Think of a stack of (5)2'x2' summer fans jutting out from the back above the back bumper. Then another (4)across the top edge. They are on piano hinges to swing out of the way when you back up to a loading dock and its padded sides/top.
Another analogy here is the diesel locomotive : diesel engine runs generator runs electric traction motors powering the rail wheels. Can the same idea be translated into/onto the semitruck? Could it improve your mileage more than the aeroshell over the cab? Talk to an aerodynamic engineer...
Gas/fuel prices have dropped dramatically in just 9 months but you know it's an illusion, when they shoot back up again, many of you will get squeezed out of business. Could this aerothrust concept give you the edge when that day inevitably comes? Go figure> W=P