[aerohead]

There IS some confusion over Kamm's contribution to aerodynamics.My reading shows that by discharging engine bay air at the base of the windshield,Kamm was able to prevent air from stalling over the windscreen header,allowing attached flow over the roof that would otherwise separate.It was up to the auto designer to chop the body wherever they chose.Airflow would remain attached up to the chop.Kamm's K-car' roof extended to the rear extremity in a continuously descending arc(ie.the "Kamm-back"),and is what people associate with Kamm,not the front-end work that made the attached flow possible in the first place! In nature,we don't see the cropped posterior,as in the K-Car as Nature seems to demand eeking-out the last ounce of efficiency,only found in the long tapered tails we refer to as "boat-tails".It is claimed that truncating the boat-tail ,will produce a "phantom"boat-tail behind the car and its kinda true.I posted a picture of the K-Car in the Volkswagen wind-tunnel over at maxmpg in the Misc.photos.The smoke trace clearly shows the "phantom",however these truncated boat-tails never actually produce the low drag of the long tail.In the movie,"The World's Fastest Indian" we can see Burt Munro's "Munro Special"at speed at Bonneville.The body on the bike takes advantage of the Blue-fin Tuna form for low drag and record-setting speed,however,as is pointed out in the story,it also demonstrates challenges to directional stability associated with center-of-gravity/center-of-pressure domains.BNI will not allow racers to run the course if crosswind speeds get to around 7-8mph,to protect against "weather-vaneing",which could be catastrophic should the vehicles be pushed into a barrel-roll.The T-100 appears to respond favorably to it's truncated boat-tail.I have planned a full 5.5:1 fineness ratio truck/trailer boat-tail,which will allow the vehicle combination to achieve the theoretical ideal form,a full tail extending twelve feet beyond the rear bumper of the T-100.Formulas show a possible 47-mpg at 70-mph.I believe this to be a reach,however it is enticing,and I won't know until I try.As Peter has pointed out,the Kamm-back is a compromise,and in the workaday world avoids the ridiculous lengths I'm going to explore with the trailer.Lower rooflines are the only thing that will allow shorter length and lowdrag together(active-suspension would help).