Ducting pressure air from front to rear?

[aerohead]

Originally Posted by Tesla

One of the ideas I was considering is just opening a rear vent, as part of the internal venting, dual benefit, may help pull air through vehicle better for ventilation, hence minimise fan use and also put air into the rear vortex and reduce it's size & volatility.
Even though it is only a small amount of air, I imagine it's effect would also follow the cubed equations for velocity & force, hence a small amount of air may have a measurable effect.
Agreed, once you start using power to create the aero effects, benefits can be marginal or negative, so my thoughts are mainly to look at passive ways of moving air from high pressure zones to low pressure zones.
Will try and locate the article you mentioned.

At 60 miles per hour and around 35 square feet of frontal area you'd be displacing over 11-million cubic feet of air per hour/185,000 CFM.That's a lot of air to dilute.

[shovel]

In anything relating to commercial equipment it's important to remember that things have to be seamless, immune to failure and tolerant of abuse. It's no savings if your innovation fails, or if it exposes your customer's shipment to weather, or costs you hundreds of pounds of billable weight, or costs you 20 minutes of headache daily.

I could imagine some scheme by which the top half of a box's rear doors fold down, and flaps open at the front of the box - both coupled to a "sock" stuck to the ceiling. At speed, the sock could inflate, conveying air from front to rear while conforming to the shape of the freight and protecting that freight from rain... but ultimately something like that would still need to be nearly indestructible, I've scraped the ceiling of many a trailer while loading crates and oddly shaped wrapped skid, it's just not something I'd expect a fabric sock to tolerate.

Maybe a telescoping roof trailer, that works like a pop up camper? I'm sure Fruehauf and Freightliner and anyone else in the freight box business has been brainstorming all of these measures, as with any market you have to innovate or die.

[Frank Lee]

^Exactly. I've been scheming telescoping this and that but so far it always ends up being extra cost, weight, and complexity coupled with less fool-proofness.

[botsapper]

Present aerodynamics controversy in state-of-art racing.

Supposedly passive, DRS-activated F-Duct.

http://www.youtube.com/watch?v=u7nba...=youtube_gdata

F-Duct: now illegal, driver controlled/active ducting for rear downforce control. Mclaren F Duct How Works - VidoEmo - Emotional Video Unity

W-Duct: Passive/active aerodynamic front wing control.

http://www.youtube.com/watch?v=r6NiK46JTEU