The M20 was the 20th design from Al Mooney, and his most successful. The series was produced in many variations over the last 50 years, from the wooden-wing M20 and M20A models of the 1950s, to the M20TN Acclaim that debuted in 2007.
On 5 November 2008, the company announced that it was halting all production as a result of the late-2000s recession, but would still provide parts and support for the existing fleet.
With the injection of Chinese capital after the company's purchase, production of the M20 resumed in February 2014.
The Mooney M20 series has been produced in three fuselage lengths: the "short-body" through M20E, "medium-body" (M20F through M20K), and "long-body" types. Although all M20s have four seats, the fuselage length increase provided more rear passenger legroom, but with a slight performance decrease. Other airplane improvements over the years in most cases more than compensated for the effects of a longer fuselage; for a similar engine and vintage, for instance, the shorter-fuselage model is faster, e.g., M20E vs M20F.
In July 2008, Mooney signed a memorandum of understanding with Rolls-Royce to develop a version of the M20 that was to have been powered by the Rolls-Royce RR500 TP turboprop powerplant. The project was announced as being a joint "marketing investigation" and "exploration project", but does not appear to have come to fruition.
With the exception of the wooden wings and tails of the original M20 and M20A, M20s are all-metal, low-wing aircraft. The wings are of cantilever construction, consisting of a main spar and an auxiliary spar that extends from the fuselage to the middle position of the flaps. The wing skin is aluminum which is flush-riveted in many areas to reduce parasitic drag. Slotted flaps cover 70% of the trailing edge. The earliest models (prior to 1963) have manual flaps. Later models use a hydraulic hand pump to control the flaps while even-later models have electrically operated flaps. The forward fuselage has a steel tube cabin structure covered in aluminum skin, while the aft fuselage is of semi-monocoque design.
The tricycle landing gear legs of the Mooney M20 models are made of heat-treated chrome-molybdenum steel. The main gear legs are attached to the main wing spar, while the nose gear is mounted onto the steel cabin frame. Rubber discs, as well as spring steel, around the legs allow for compression and shock absorption on landing. Except for the fixed-gear M20D, the nosewheel retracts rearwards and the main wheels retract towards the fuselage. Early models use a hand-operated lever system to raise and lower the gear. Later models use an electrically operated landing gear retraction system with a backup crank-operated or wire-pull gear extender.
The Mooney M20 has medium aspect-ratio tapered wings, incorporating 1.5° of washout and 5.5° of dihedral. On the M20J, navigation and anticollision lights are located inside an aerodynamically designed cover at the wingtips to further eliminate drag. Later M20s are equipped with stall strips to improve the stall characteristics.
The empennage of the Mooney M20 is easily recognizable by its unique tail fin with a vertical leading edge. (The tail fin looks as though it is "leaning forward", but it is approximately vertical in level flight, depending on trim setting.) The horizontal tailplane, which consists of fixed stabilizers and trailing elevators, has no trim tabs. The entire tail assembly pivots at the rear of the fuselage to provide pitch trim.
All M20s store fuel in two separate "wet wing" tanks, which are located in the inboard sections of each wing. Fuel is driven from the tank to the injectors or carburetor by an engine-driven pump, backed up with an electric boost pump. Deterioration of the wing tank sealant can be a problem, leading to expensive rework of the tanks. A modification is available to install rubber bladders inside the existing tanks.
For increased power many M20s also have a ram-air induction system, called the Mooney "Power Boost". For normal operations, the intake air is filtered before it enters the induction system. When ram air is selected, partially unfiltered air will enter the induction system with a higher pressure and consequently the manifold pressure will increase about a full pound per square inch when flying at 7500 feet above mean sea level, giving a greater power output. The turbocharged variants omit this feature, as the turbocharger provides a far greater increase in manifold pressure.
M20 and M20A
The original M20 (1955–1958) and the M20A (1958–1960) have wings made of wood covered with cloth, but are otherwise similar to later all-metal models. With the M20A, the power was increased from the M20's 150 hp (110 kW) Lycoming O-320 to the 180 hp (130 kW) Lycoming O-360-A1A or A1D.
Early in the model's history, several incidents of wooden tails breaking up in flight occurred due to water damage and the resulting rot. Consequently, most tails have now been replaced with all-metal copies, as required by Mooney Service Bulletin M20-170A and the FAA Airworthiness Directive 86-19-10. Without the possibility of metal fatigue, the wooden wing has an indefinite life expectancy and is considered by some pilots to provide a smoother ride in turbulence.
The M20 received its type certificate on 24 August 1955, with the M20A following on 13 February 1958.
The M20B was type-certified on 14 December 1960, with the 180 hp (130 kW) O-360-A1A or A1D engine.
An M20C Mark 21
In 1962, Mooney made further incremental improvements in the M20C Ranger, produced between 1962 and 1978.
The M20C was type-certified on 20 October 1961, with the 180-hp O-360-A1A or A1D engine.
In 1963, Mooney introduced the M20D Master, essentially an M20C with fixed gear and a fixed-pitch propeller.
The M20D was type-certified on 15 October 1962, with the 180-hp O-360-A1D or A2D engine. Many M20Ds have been converted to the M20C model, and may appear in registration records as M20D/C.
A very early production 1964 model Mooney M20E Super 21
A 1965 Mooney M20E Super 21 with 201 style modifications
The first truly high-performance Mooney, the M20E, was produced from 1964 to 1975 and marketed as the Chaparral and Super 21.
The M20E was essentially an M20C with a more powerful 200 hp (150 kW) fuel-injected engine. It was type-certified on 4 September 1963, with the Lycoming O-360-A1A engine.
Turbonormalizing, which maintains engine performance at higher altitudes, is available as an aftermarket option for the M20E, F, and J.
M20F and M20G
Mooney M20F Executive
Mooney stretched the fuselage and initially added a third fuselage side window with the M20F Executive 21, which was produced between 1966 and 1977. The M20F is otherwise similar to the M20E.
The M20F was type-certified on 25 July 1965 with the 200 hp (150 kW) Lycoming IO-360-A1A engine, with the M20G following on 13 November 1967, equipped with the 180 hp (130 kW) Lycoming O-360-A1D engine.
Mooney hired Roy LoPresti to undertake an aerodynamic cleanup of the M20F, resulting in the 1977 model year debut of the M20J. The M20J was marketed under the name Mooney 201 because of its 201 mph (323 km/h) top speed in level flight. The M20J first flew in September, 1976, and was type-certified on 27 September 1976. It is equipped with the 200-hp IO-360-A1B6D, -A3B6D or -A3B6 engine. Besides the more sloped windshield, the M20J and K can be differentiated from the earlier models by their longer rear windows in place of the rear two windows of the M20F.
Up through the M20J, all Mooney M20s had four-cylinder Lycoming engines. After designing the M20J, Mooney modified the basic design to include a variety of more powerful six-cylinder engines, including some models with turbocharged engines. The first such design was the turbocharged M20K, which was produced between 1979 and 1998.
The M20K was marketed as the Mooney 231. This model's Continental TSI0-360-GB engine required specific pilot training and modified takeoff and climb procedures to operate at acceptable engine temperatures in hot weather, so by 1986, it was replaced with an intercooled TSIO-360-MB engine, reducing the temperature problems and achieving a top speed of 252 mph (406 km/h) in level flight (at FL 280). This subvariant of the M20K was marketed as the Mooney 252.
The M20K was type-certified on 16 November 1978. It is equipped with the Continental TSIO-360-GB1 -GB3, -GB4, -LB1, -MB1, -MB2 or -SB2 engines. All produce 210 hp (160 kW), except the -MB1 and 2 and the SB1, which produce 220 hp (160 kW).
In 1988 Mooney, went to even greater lengths, partnering with Porsche to include their geared single-lever Porsche PFM 3200 N03 engine, derived from the 911 Carerra engine of 217 hp (162 kW) and stretching the fuselage for the last time to produce the first long-body M20. Most M20Ls no longer use this unique engine, as factory support ceased in 2005. M20L production ended in 1990. This model was marketed as the Mooney PFM.
The M20L achieved type certification on 25 February 1988.
The M20M (1989–2006) boosted output initially to 270 hp (200 kW) and was also turbocharged. The M20R (1994–) started at 280 hp (210 kW) and was normally aspirated. With minor changes in engine output (e.g. the M20S "Eagle") and various performance tweaks, these two basic models (both high power, both with long bodies, one with turbocharging) are known as the "Bravo" and "Ovation".
Introduced in 1994, the M20R Ovation mated a long-body fuselage to a Continental IO-550-G normally aspirated powerplant of 280 hp (210 kW). This model was named Flying Magazine's single-engine plane of the year in 1994.
The M20R was type certified on 30 June 1994, and is equipped with the 280 hp (210 kW) Continental IO-550-G(5), -G(6) or -G(7) engine.
The M20S Eagle introduced in 1999 was powered by a Continental IO-550-G engine of 244 hp (182 kW). In 2001, the Eagle 2 was introduced. This model included such refinements as a three-bladed propeller, a 100 lb (45 kg) gross weight increase and a standard leather interior.
The M20S was type-certified on 7 February 1999, and is equipped with the 244 hp (182 kW) IO-550-G(6) engine.
Mooney M20T Predator prototype, N20XT, on display at Sun 'n Fun 2006
The M20T Predator, a canopy-equipped version of the basic M20 design powered by a Lycoming AEIO-540 engine, was Mooney's entrant in the USAF Enhanced Flight Screener competition. The prototype, built in 1991, displayed in a tiger-stripe paint scheme. The contract was won by the ill-fated Slingsby T-67 Firefly, and the M20T was not developed or certified. The sole prototype, registered N20XT, was flown in the Experimental - Market Survey category and was still owned by Mooney Aircraft in 2013, although its registration had expired 30 November 2013.
Mooney M20TN Acclaim
The M20TN Acclaim is the latest version of the M20 design produced, and is powered by a turbonormalized Continental TSI0-550-G powerplant with twin turbochargers and dual intercoolers. The Acclaim replaced the Mooney M20M Bravo in the company product line.
The M20TN was type-certified on 15 October 2006. and is equipped with the 280-hp TSIO-550-G(1), -G(2), -G(3) or -G(4) engine.
Mooneys derive their performance from a clean airframe with drag reduced by refinements over the years. Many of these refinements are supplemental type certificate (STC) modifications to the airframe developed by aftermarket businesses. Some of these modifications have been incorporated into the factory production models.
In 1990, Rocket Engineering Corp. of Spokane, Washington, modified an M20K 231 model by replacing the standard turbocharged 210 hp (160 kW) Continental TSIO-360 engine and two-blade propeller with a turbocharged 305 hp (227 kW) Continental TSIO-520-NB and a McCauley three-blade propeller. This engine and propeller combination had previously been proven on the twin-engined Cessna 340 and Cessna 414. Marketed as the Rocket 305, this variant delivered a 228-knot speed and 1,600 feet/minute rate of climb. This significantly increased performance, but at the expense of higher fuel consumption.
The 305 Rocket STC represented a 21⁄2 year certification effort, including 1,000 flight test hours. The plane passed all FAA flight test requirements, including spin, flutter, load, cooling, and noise tests. The STC covered both the 231 and 252 M20K variants. While the 231 and 252 had a maximum certified altitude of 24,000 ft (7,300 m) and 28,000 ft (8,500 m), respectively, the engineering goal of the Rocket 305 was certification for a maximum altitude of 31,000 ft (9,500 m). Extending the altitude in the STC was abandoned due to cost/benefit considerations versus the difficulty of demonstrating compliance with the FAA requirements, plus required changes to the supplemental oxygen systems in this non-pressurized aircraft. The aircraft will, however, climb at nearly 1,000 ft/min above 24,000 ft (7,300 m). The Rocket conversion was discontinued by Rocket Engineering. The production-version Mooney Acclaim now delivers faster speeds. As Rockets are available in the used market for about one-third the cost of a new Acclaim, it maintains its popularity among a small market niche.
The Mooney Super M20E is the aircraft most closely associated with Robin Miller, an Australian female pilot known as the "Sugar Bird Lady" for her work in distributing the polio vaccine across Australia.