When we designed and built the Cosman Special in the late 1980's, the mission profile was simple: get my Granddad from Riverside to Salt Lake as fast as possible, using a stock A65 engine, without compromising safety. Ron Caraway now owns the Special, which he has perfected into the gorgeous "Betty Boop", and it now cruises at 200 mph. But Dad was the runt of the Cosman Clan at 6'2" 200 lbs, and the rest of us got tired of shoe-horning ourselves into both home- and factory-built aircraft designed around the FAA's mythical 5'10"/170 lb pilot. So we decided to design an airplane for big people.

We started with a cockpit mockup sized for the tallest of us (at 6'6"), and wide enough to fit two of the largest people around, or a normal person and two kids. We put the people and the fuel on the center of gravity to minimize sensitivity to loading. The seating posture is fairly upright, so you don't need to be a gymnast with tremendous upper body strength to levitate yourself in and out.

All things being equal, the airplane with the longer wing performs better, so we designed a 30' wing with three sections of Fowler flaps to lower the landing speed, and a fairly thick airfoil section to provide lots of lift and a gentle stall. An added benefit is lots of depth to hold fuel and provide strength.

Nearly everybody goes back later to make their tail larger or put it farther back, so we gave the design a generous V tail on a long moment right from the start. This allows us to run in the forward part of the CG envelope with minimal pitch trim drag, while providing extra stability.

The Mazda-derived rotary engines have some intriguing advantages for aircraft use. They are compact, smooth, potent, and have no catastrophic failure modes. The three-rotor 20B is capable of 290 hp normally aspirated, at a firewall-forward weight of less than 500 pounds. The airframe was designed with the rotary in mind, although it could accommodate certified engines up to 250 hp.

Currently, with the addition of wheelchairs to our family, this project has fallen by the wayside in favor of an airplane that is easy to get into.  It would seem that a person’s ability to get into an airplane is inversely proportional to their ability to buy an airplane;  meaning, the older we get the more we can afford to fly, but the less able we are to perform the physical moves to board the aircraft.  See the Cosman LSA for our solution to this problem.