I have some interest in this as am trying to determine best directions for my vehicle, now it's nowhere near as big as a full size Semi, but it doesn't quite fit the road going sedan or hatch either, and there doesn't really seem to be any research around for that large 4x4 wagon or van type body, particularly with higher ground clearance.
The question of optimum boattails has come up a number of times and even though the template type profile seems to be the right direction for regular road vehicles, but this does not seem to be what the truck studies are applying.
I know there are length constraints in that case, but that doesn't really explain why they consistantly present the optimum boat tail as having an angle of 10-18°, I can understand some of the studies getting it wrong, but not all of them, they have the same data and history available to them.
It may well be that they are getting seperation towards the end of their boattails, and are maxing out on their limits, but like in my case where additional length really is impractical maybe their is something to be gleamed from these truck/trailer applications.
If we can only do 12 or 18", then what really is the optimum angle, according to the template it would be somewhere between 3.5 -7° and essential curves,
but the truck data says we might be able to do 10° or more straight off the bat?
Here's some of the links I looked at:
http://www.transtexcomposite.com/dat...report_sae.pdf
Green Car Congress: New Boat Tail Design Could Improve Class 8 Truck Fuel Economy by 10%
http://repositories.tdl.org/ttu-ir/b...pdf?sequence=1
http://www.kronosenergysolutions.com...E-TMAtests.pdf
https://e-reports-ext.llnl.gov/pdf/460425.pdf
http://www.nvfnorden.org/lisalib/get...px?itemid=3446
http://ecomodder.com/forum/showthrea...-18151-14.html
Aero RV tail is there at the end also as some of these questions were raised there ass well and the boat tail is also more like the Dryden van and seems to produce a very good result.