The Cozy Mk IV is a four-place, high performance, homebuilt airplane. It is a pusher-canard type configuration, based on the Long-Ez by legendary designer Burt Rutan. Cozy designer Nat Puffer originally built the Cozy as a Long-Ez with a side by side front seat configuration, and a single seat in the back. Nat then decided to add a second seat in the back, which brought about the need to call it the Cozy Mk IV, while the original became known as the Cozy III. The Cozy Mk IV cruises at 170+ kts, and has a range of over 1000 NM, depending on how it is configured. The plans call for a Lycoming O-320 or O-360, but many builders have put in IO-360s, IO-540s, a range of automotive engines, and there are even jet powered Cozys flying.
Like all derivatives of Rutan designs, the Cozy is a composite airplane, built using a moldless construction system consisting of laying up fiberglass cloth and epoxy over shapes made of varying kinds of foam. This “sandwich composite” structure is considerably stronger per unit weight than aluminum structure, the most common type of structure in aircraft construction.
The canard-pusher configuration, another Rutan hallmark, allows the aircraft to be much more efficient. With a conventional airplane, the horizontal stabilizer is actually providing negative lift, in order to offset the weight of the engine. Imagine it this way… an airplane rotates around it’s center of lift, which in most airplanes, is near the center of the wing. In a conventional “puller” airplane, the weight of the engine is acting on one side of this pivot point, and the horizontal stabilizer has to provide an equal force in the opposite direction in order to keep the plane from nosing down. Whenever a wing (or any surface) is creating lift, it also creates drag. With the configuration of canard-pusher aircraft, the engine is very close to the center of lift, and does not need a compensating force, so both the canard in the front and the main wing are free to create positive lift. Therefore, the ratio of lift to drag is much higher on a canard type aircraft, and it flies much more efficiently.
We decided to build a Cozy for several reasons; it has excellent cross country capability, it’s super fast, it’s composite (which I find fascinating), and it is plans built. Being plans built, you build (almost) everything from scratch. Building from scratch has some disadvantages, as it takes considerably longer than a kit built plane, and you don’t really have any reference other than the drawings. The major advantage with a plans built aircraft, however, is that you buy the materials you need as you go, instead of laying out a huge chunk of cash for all the kit components up front.
To learn more about this amazing aircraft, visit the links provided on the right column of this site. The unofficial site is quite informative, and Marc Zeitlin deserves a lot of credit for giving such a great resource to Cozy builders, flyers, and enthusiasts.