The Ultraflight Lazair is a family of Canadian designed and built twin-engine ultralight aircraft that were sold in kit form between 1979 and 1984. 

The designer of the Lazair, Dale Kramer, was an aeronautical engineering student at the University of Toronto when he attended the Oshkosh EAA convention in 1977. He was very impressed with the potential of the ultralight aircraft designs that he saw there and returned with a Superfloater glider kit. Convinced that improvements to the design were possible, Kramer started with a blank sheet of paper and designed a completely new aircraft, even going so far as to design a custom airfoil for it.

The design features a constant taper wing with a progressive and constant washout from root to tip. Combined with an airfoil that is cambered with concave portions on both the top and bottom surfaces, this produced an aircraft with optimized low-speed handling and very gentle stall characteristics. The wing is constructed from an aluminum "D" cell leading edge, foam ribs and an aluminum tubular trailing edge. The aircraft also featured some of the first winglets used on light aircraft.

The very long wing made the Lazair a good glider, giving it a 12:1 glide ratio, and it could be soared in even light thermal conditions.

Kramer named the aircraft “Lazair” as a contraction of “Lazy-Air”, a comment on the slow cruise speed of the aircraft, which was about 40 mph (64 km/h).

The Lazair incorporated standard aircraft materials but had innovative design features in every component, including:

• winglets
• full three axis controls (unusual in ultralights in 1978)
• inverted V-tail with ruddervators
• transparent PET film covering for the wings and tail surfaces
• twin engines for safety

Initially Mylar was used as a covering on the wings and tail, attached to the airframe with two sided tape. After the Mylar proved to have a short service life due to UV damage, it was replaced by a more expensive product, Tedlar.

For control run simplicity the control stick pivot point was located above the pilot with the stick hanging downwards. The ailerons and ruddervators on the inverted V-tail were interconnected so that turns were made with connected rudder and aileron by moving the stick to the side. Pitch control was via conventional fore-and-aft stick movement moving the ruddervators together as elevators.

Because Kramer could not find a suitable engine for the design that provided the needed power with reliability, he opted for two engines instead, placed as close together as possible to reduce yaw when one failed. The entire concept was to produce an aircraft that would fly with minimum power and so the prototype had two chainsaw engines that produced a total of 11 hp (8.2 kW).

The first Lazair prototype was constructed by Kramer and his friend and associate Peter Corley and first flew in 1978.

Kramer formed Ultraflight Aircraft to produce the design in his home town of Port Colborne, Ontario. Sales commenced in 1979 through the subsidiary "Ultraflight Aircraft Sales".

Lazair production commenced in 1979 and was completed in 1984, the company citing “liability concerns” and the resulting cost and availability of insurance as the reason.

The aircraft were widely sold in Canada and the United States and sales totaled more than 2000, making the Lazair the most produced Canadian aircraft design. The Series II Lazair was the most produced individual model.

The Lazair inspired many other aircraft designers to use the Lazair wing construction techniques. The Blue Yonder Merlin is one aircraft that uses a wing based on the Lazair wing.

Source: Wikipedia