The modification that Larry Vetterman shared in todays (2-5-09) VAF home page daily news is a major breakthrough in speed mods I believe. It is tested on an "A" model which makes it all the better from my prospective. He says that he is going to try to modify the design to work with existing exhaust system configurations but I do not believe it will be as successful as the configuration he has tested with the outboard exhaust placement. I have been thinking of something like this for some time but had done nothing to bring it past the brain to reality. His implementation is so perfect in appearance that it is hard to imagin anything better. The outboard exhaust position is required for max gain I believe but I was thinking of some short modification of the basic lower cowl with a reflex after the FAB to a tail like you see in the landing gear fairings - not faired down (up actually) to the fuselage as Larry Vetterman has done. This would require a removable section in the honeycomb structure of the lower cowl with a lot of messy accomodation work. The way he has added the fairing on behind the existing cowl is perfect. The mounting he has chosen onto the lower fuselage can easily be accomodated with platenuts and maybe some doubler plates. Man I love it! I am thinking of delaying the control surface end pocket filling till later in the racing season (www.sportairrace.org calendar of events) and try to get this in. I think a cowl flap needs to be incorporated in place of the louvers and I think the pressure recovery style may be even faster than the half teardrop approach. The beauty of this concept is you an make as many configurations as you want an substitute them just by picking up the same mounting points. All of the existing out board tank and fuel pump vents will have to be relocated away from the outboard exhaust location. THIS IS BIG!
Bob Axsom
Bob Axsom