artwebb wrote:the consensus being that the dirty air is still air, and the aerodynamics of a vehicle do matter, even in dirty air.
I think it's important not to mix up two different things:
- 'Dirty air' to me implies air that has previously travelled over/around another body some distance ahead. This will cause disrupted flow over a following body but won't reduce its drag by much, if at all. A good example is how big-winged racecars lose lift when following another one.
- 'Wake' is another matter. This is the air that is being dragged along behind a vehicle and so a following vehicle will experience substantially reduced drag. In this case, the shape of the trailer won't make much difference, unless parts of it extend out of the wake.
I would say that a teardrop at a conventional distance behind the tow vehicle is mostly in the 'wake' condition, but with its outer edges (top, sides) in the 'dirty air' condition. So neither clearly one thing nor the other!
artwebb wrote:the let in bracing was to counteract the massive air pressure (aerodynamic force) of an unaerodynamic design.
Before we see a spate of little trailers built with 'wind bracing', it would be good to make it clear that this isn't needed if the trailer body is clad in sheets of plywood which is glued and/or securely nailed in place.
bobhenry's barn looks like it's clad in strip wood, but I see from his album that there's plywood underneath:
In this case, the plywood itself acts as perfectly good 'wind bracing'. Wind bracing may be needed on houses, where the attachment of the plywood skin is so flimsy that the joints don't achieve the full strength of the plywood, but that isn't the case in a well-built trailer.
If this doesn't seem 'right', just scale up a trailer body to the size of a house - a house sheeted on all sides with one continuous sheet of 3" thick ply glued to the framing wouldn't need wind bracing either.
Andrew
