[aerohead]

I used some rolling resistance values from CATERPILLAR's online 'UNDERSTANDING TRACTOR-TRAILER PERFORMANCE' and estimated a BSFC of 0.537 for the naked F-150.
Using this BSFC,I used the towing mpgs to reverse-engineer the road loads necessary to explain the difference.
I came up with 3.72-hp rolling resistance penalty for the loaded trailer, and 14.364-hp additional aero losses.
Using the frontal area of the pickup as a reference,the aerodynamic loading of the trailer/Kubota tractor combination creates a tax on the F-150 equivalent to raising it's drag to Cd 0.691,up from Cd 0.34 for the solo Aerolid combo.
From Caterpillar,the rolling force coefficient for the set of 4-tires,and any powertrain friction,at 55-mph is 0.00802205,based on the all-up weight of the truck.
I used the same coefficient to estimate the trailer R-R load.
If any members want to run the numbers as well,Based upon AeroStealth's values,it would be good to have a second set of eyes on this.
I feel like quite the neophyte when it comes to trailers.
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PS @ Cd 0.691 and 36-sq-ft we get CdA 24.876 sq-ft.
If we consider APEX's 62-sq-ft frontal area as the reference for the 'rig',then to get 14.5 mpg towing APEX at 55-mph,the Cd of the F-150/trailer combo would need to be no greater than Cd 0.401? (A little better than a NASCAR 2-car draft)