The Cessna 172 Skyhawk is a four-seat, single-engine, high-wing airplane. More Cessna 172s have been built than any other aircraft and it is also probably the most popular flight training aircraft in the world.

The 172 is a direct descendant of the Cessna 170, which has conventional landing gear in place of the 172's tricycle gear.

The Skyhawk is part of a large family of high-wing, tricycle-gear, single-engine Cessna planes, ranging from the two-seater 150/152 (no longer in production) to the more powerful 182 Skylane, the six-seat 206 Stationair, and the fourteen-seat turboprop 208 Caravan, along with several other models no longer produced.

Development

The first production models were delivered in 1956 and it is still in production in 2006; more than 35,000 have been built. The Skyhawk's main competitors have been the popular Piper Cherokee, the Beechcraft Musketeer and Grumman Cheetah (both no longer in production), and, more recently, the Diamond DA40 Star and the Symphony SA-160.

Early 172s looked almost identical to the 170, with the same straight aft fuselage and tall gear legs, but later versions incorporated revised landing gear, a lowered rear deck, and an aft window. Cessna advertised this added rear visibility as "Omni-Vision". The final structural development, in the mid-1960s, was the sweptback tail still used today. The airframe has remained almost unchanged since then, with updates to avionics and engines including most recently the optional Garmin G1000 glass cockpit. Production ended in the mid-1980s, but was resumed in 1996 with the 160 hp (120 kW) Cessna 172R and 180 hp (135 kW) Cessna 172SP.

The older Skyhawks were delivered with a 145 horsepower (110 kW) engine, while later versions were equipped with engines up to 180 horsepower (135 kW), though 150 or 160 hp (110 or 120 kW) is more common. A rare modification of engines allowed the installation of a 220 hp Franklin engine.

The Cessna 172 started life as a relatively simple tricycle undercarriage development of the taildragger 170, with a fairly basic level of standard equipment. First flight was in November 1955. The 172 became an overnight sales success and over 1400 were built in 1956, its first full year of production.

The basic 172, with 2200 pounds maximum gross weight, remained in production until replaced by the 172A of early 1960. The 172A introduced a swept back tail and rudder, while the 172B of late 1960 introduced a shorter undercarriage, equipment changes and for the first time the Skyhawk name for the Deluxe option (added optional equipment sold as a package, with full exterior paint vs. partial paint).

The 172D of 1963 introduced the cut-down rear fuselage with wraparound rear window. The 172F introduced electric flaps and was also built in France by Reims Cessna as the F172 through to 1971. It also formed the basis for the US Air Force's T-41A Mescalero primary trainer. The 172G of 1966 introduced a more pointed spinner, while the 172H was the last Continental powered 172.

The Cessna Company planned on dropping the previous 172 configuration for the 1968 model year and replacing it with a similar but cantilever-wing/stabilator aircraft to be called the 172J. However, as time for model introduction neared, those dealers who were aware of the change began applying pressure on the factory to continue the previous configuration, as they felt the new model would be less useable as a trainer. Therefore, at the last minute the decision was made to continue the 172 in its familiar configuration, and the new configuration would be introduced as a NEW model. So the 172J became the 177, and the deluxe option of the 177 became the 177 Cardinal. The familiar 172 needed to be re-engined, because Cessna had canceled its contract with Continental for the venerable six-cylinder 0-300 engine of 145 horsepower. Fortunately, the lighter (four-cylinder) but more powerful (150 horsepower) Lycoming engine planned for the 172J would also be available for the familiar 172 with few modifications, so the decision was made to continue the 172 as a Lycoming-equipped model, known as the 172I (the I model is usually not used, since it causes confusion due to its similarity to the number 1). The designation 172J was never publicly used; the next upgrade to the 172 line was named 172K in 1969. It (172K) had a reshaped vertical fin cap, and its rear windows were reshaped. Optional larger wing fuel tanks were offered. The 1970 model was still called the 172K but carried reshaped (downward-shaped conical fiberglass) wingtips. Its main landing gears, which originally were flat steel springs, were replaced with tapered tubular steel units. The tubular units were lighter but required aerodynamic fairings to keep the same speed and climb performance.

The 172L, sold during 1971 and 1972, had a plastic fairing between the dorsal fin and vertical fin, to introduce a greater family resemblance to the 182's vertical fin. The 172M of 1973/76 gained a drooped wing leading edge for improved low speed handling. The 172M was also the first to introduce the optional `II' package of higher standard equipment. Also in 1976 Cessna stopped marketing the aircraft as the 172, using only "Skyhawk" for marketing purposes from that time forward.

The 172N, produced for the 1977 model year, was powered by a 160 horsepower (120 KW) O-320-H designed to run on 100 octane fuel (all previous engines used 80/87), but the engine proved troublesome and was replaced by the similarly rated O-320-D in the 172P of 1981. The P was the last basic 172 model, remaining in production until 1985.

The 172R was introduced in 1996 powered by a 160hp Lycoming IO-360L2A. This was the first Cessna 172 to have a fuel-injected engine. The maximum takeoff weight of the 172R is 2,450 pounds (1,113kg). The 172R introduced many improvements including a new interior with contoured front seats which adjust vertically and recline, an all new multi level ventilation system, standard four point intercom, interior soundproofing, and energy absorbing 26g seats with inertia reel harnesses.

The 172S (Skyhawk SP) represents the most modern development of the Cessna 172. Introduced in 1998, it is powered by a 180hp Lycoming IO-360L2A. The maximum rpm was increased from 2400 rpm to 2700 rpm to deliver a 20hp increase over the 172R. The aircraft is geared to owner-operators, with leather seats and the maximum takeoff weight increased to 2,550lbs (1,157kg). As of 2007, both the Cessna 172R and Cessna 172S are offered in the Cessna product range and the Garmin G1000 avionics package is standard.