[aerohead]

The members have made some really good recommendations.If you can imagine the pickup and trailer as a single unit,with the body flowing up from the rear of the cab to the top of the trailer,filling the entire void,top to bottom,this would be ideal.Besco,of Northhampton,England,marketed an inflatable trailer nose which attached to travel trailers and created a semi-spherical nose when inflated with a 12-volt vacuum cleaner.I believe they claimed a 28-percent mpg improvement.If you could build a cheapy skeleton( maybe two-by-twos and angle brackets) for the bed rails of the truck and skin it with the chloroplast,you'd have a good transition.If you did as Otto recommends,and also push the nose of the trailer forward,like the stock trailer,then your filling in the gap that you see 18-wheelers trying to seal off,which offers significant drag.And as Techtricks (sp?) and Otto have mentioned,clean up anything on the trailer that you can.The fenders are horrible! Fair the leading edges,boat-tail behind them,and put skirts on if you can.Someone posted the NASA/Continuum Dynamics 4-panel faux-boat-tail,which was good for up to a 10% drag reduction.It's just 4 rigid panels that extend straight back from the back of the trailer.They are inset,and extend such that when viewed from the side or top,they limit the air to a path that would be defined by a 12-15 degree angle,converging behind the trailer.The panels create "locked" or "captured" vortices,as Ford's bi-wing spoiler,and the air flows over the vortices as though they were a solid structure.If you get into strong crosswinds,slow down!!!!!!!!!! Your rig will be an "unknown quantity" and you will have no fore knowledge of your center of gravity, center of aerodynamic pressure,and it's handling behavior.Be careful,we want to hear all about the results.P.S.,you could also sew up an inflatable envelope of rip-stop nylon to do some of the big streamlining and keep it around for some future moves,or to loan to another member for research.