This article originally appeared in Kitplanes, April 2008.Those of you who attended that big airshow in the state of Wisconsin a year ago might have noticed a curious juxtaposition. If you had started a soft-serve ice cream before dropping by the Van's Aircraft booth to see the RV-12 prototype, you probably would not be licking the cone by the time you arrived in Camp Schlitter, where the RANS S-19 -- painted, primped and well along in flight test -- rested outside the tent. Unless you were utterly absorbed in satisfying your sweet tooth, the similarities between the RV-12 and the S-19 would be striking. Welcome to modern, set-point design, where key parameters of Light Sport Aircraft are tightly grouped and the result is, for now, many similar-looking aircraft crowding the fence line. When two intelligent and prolific designers like Randy Schlitter and Richard VanGrunsven arrive at more or less the same place, you know orthodoxy is just around the corner. Actually, it's not that simple. First glances have the RV-12 and the S-19 as adjoining peas, but they issue from dissimilar legumes. The general proportions are similar, plus they are all-metal, low-wing, engine-in-front, bubble-canopy designs using a 100-horsepower Rotax 912S, which seems to be the configuration of choice among new LSA- intended designs. One of the liberating qualities of the current Light Sport regulations is that human factors can be brought forward, while pure performance tends to take a step rearward. After all, the top speed is set at 120 knots (138 mph) at maximum continuous power at sea level. By the time you have enough wing to meet the 45-knot clean stall-speed requirement of the rule, plus sufficient tail volume to meet stability requirements (as in the ASTM specs), it's unlikely that any design is in danger of whipping past the speed limits, though some designs are definitely walking right along that line. So without having to seek maximum cruise speeds, designers can opt for a wider cabin, taller canopy and other compromises that might add a bit of drag, but all benefit the pilot and passenger rather than buff up the specifications sheet.
Listen to this and you'll understand why hypoxia makes you stupid. More