95 Percentile Person
If you have ever tried to fit in most single seat aircraft and some larger ones you might notice that you just donít fit. Generally most aircraft are designed around the mythical 50-percentile person. I say mythical, as they seem to be pretty rare around the airport here. 50-percentile means that the person is bigger than 50% of the population or in other words 50% of the population will fit into those dimensions.
For the 50 percentile Adult Man, average height is 69.1" (175.5 cm). Average weight is 172 lb. (78.4 kg). The dimensions drawn are "normal" or mean data for this age group. Human dimensions vary widely among the "normal" populations. A 95 percentile man is quite a bit larger both in height and width when compared to a 50-percentile man. Since there are no people whose body dimensions are all at the 50th percentile you can have problems. Body dimensions aren't linearly correlated so people with short arms don't necessarily have short legs, etc.
A 95 percentile person is taller, wider and heavier than the 50-percentile man. 95-percentiles are up to 76 inches in height, 225lbs. The figure below is a 50-percentile man as seen from the side. (Iíll be adding in a 95-percentile to compare as soon as I can find a suitable image). I designed the Gnat around my own size. I am 6í1Ē tall about 225lbs and have a 48inch chest. The cockpit was sized to make the fit and comfort level good enough to allow me to go flying and not have to be pryed out afterwards. In other words its big enough so that I am comfortable at all times. If you are my size or taller you wonít have problems either. If you are one of those mythical 50-percentile persons you will have plenty of room to spare. The Gnat is by no means a big airplane but it can fly with a big pilot.