- Aircraft History, Specification and Information -
Mooney M20
Mooney M20J MSE - N322DM
1993 Mooney M20J MSE
N322DM (sn 24-3294)
Photo taken at Sun 'n Fun 2007
Lakeland Airport, FL USA (KLAL)
Photo © AirplaneMart.com
Mooney 252 TSE (M20K) - C-GTIF
1980 Mooney 252 TSE (M20K)
C-GTIF (sn 25 0501)
Photo taken Aug. 2009
Penticton Airport, BC Canada (YYF / CYYF)
Photo © AirplaneMart.com

The Mooney M20 is a family of piston-powered, propeller-driven general aviation aircraft, all featuring a low-wing and tricycle gear, manufactured by the Mooney Airplane Company.

The "M20" was the twentieth design from Al Mooney, and his most successful. The M20 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 the 21st century and is currently in production.

Development

The Mooney M20 series has been produced in three fuselage lengths: the "short body", "medium body" (including M20J), and "long body" types. Only the long body Mooneys are in current production. Although all M20s have four seats, the fuselage length increase provided more passenger legroom but with a slight performance decrease. Other airplane improvements over the years more than compensated for the effects of a longer fuselage.

Variants

Mooney M20 & Mooney M20A
The original M20 (1955–1958) and the M20A (1958–1960) have wings made of wood and 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) to 180 hp (130 kW).

Early in the model's history there were several incidents of wooden tails breaking up in flight 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 provide a smoother ride in turbulence.

The M20 received its type certification on 24 August 1955 with the M20A following on 13 February 1958.

Mooney M20B
Mooney addressed the dwindling supply of woodworkers by switching to an all metal design in 1961 with the M20B. The all metal design added some weight and cost 5 to 8 knots (9 to 15 km/h) in top end speed versus the wood-wing models. There have been no reported in-flight breakups of all-metal M20s other than as a result of flight directly into a thunderstorm.

The M20B was type certified on 14 December 1960.

Mooney M20C
In 1962 Mooney made further incremental improvements in the M20C Ranger, produced between 1962–1978.

The M20C was the last short body Mooney in production, with more M20Cs produced than any other Mooney model.

The M20C was type certified on 20 October 1961.

Mooney M20D
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.

The aircraft was intended primarily for flight training and for owners seeking lower insurance rates.

The M20D lasted in production only until 1966. Most have now been converted to M20Cs for increased cruise speed and climb performance.

Mooney M20E
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 04 September 1963.

This short body Mooney still has the distinction of having the shortest takeoff runway requirement at lower elevations.

Turbocharging, which would maintain this performance at higher elevations, is available as an after-market option.

Mooney M20F & Mooney M20G
Mooney stretched the fuselage and initially added a third fuselage side window with the M20F Executive 21, which was produced between 1966–1977. The M20F is otherwise similar to the M20E.

The M20G Statesman, produced 1968–1970, was a stretched M20C incorporating the carburated 180hp engine. Many M20G owners later converted to the 200hp engine.

In 1969 Mooney made electrically-operated landing gear and flaps standard across all its aircraft. Prior to that, pilots extended and retracted the standard landing gear using a heavy metal Johnson bar. Electrically-extended landing gear was an option.

The M20F was type certified on 25 July 1965 with the M20G following on 13 November 1967.

Mooney M20J
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.

The improved aerodynamic shape and updated 200 hp (150 kW) engine made the M20J the second most popular variant of the M20 series, after the M20C. It is often used as a training aircraft for commercial pilots. It was originally designed as a private/commercial touring aircraft because of the high cruising speed and relatively low operational cost. This model was marketed as the Mooney 205. The J model had a long production run, lasting until 1998, thus ending the medium body M20 series.

Mooney M20K
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 1979–1998.

The M20K was marketed as the Mooney 231. This model's Continental TSI0-360-GB engine was challenging to operate at acceptable engine temperatures, so by 1986 it was replaced with an intercooled engine, eliminating the temperature problems and achieving a top speed of 252 mph (406 km/h) in level flight (at FL 280). This variant was marketed as the Mooney 252.

The M20K was type certified on 16 November 1978.

Mooney M20L
In 1988 Mooney went to even greater lengths, partnering with Porsche to include their geared single-lever Porsche PFM 3200 N03 engine of 217 hp (162 kW) and stretching the fuselage the last time to produce the first long body M20. Most M20Ls no longer use this unique engine. M20L production ended in 1990. This model was marketed as the Mooney PFM.

The M20L achieved type certification on 25 February 1988.

Mooney M20M
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) remain in production today as the "Bravo" and "Ovation".

The M20M was type certified on 28 June 1989.

Mooney M20R
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.

Mooney M20S
The M20S Eagle was introduced in 1999 and 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 3-bladed propellor, a 100 lb (45 kg) gross weight increase and standard leather interior.

The M20S was type certified on 07 February 1999.

Mooney M20T
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 was built in 1991 and displayed in 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 2008.

Mooney M20TN
The M20TN Acclaim is latest version of the M20 design, powered by a turbo-charged Continental TSI0-550-G powerplant with twin turbochargers and dual intercoolers. It was type certified on 15 October 2006.

The Acclaim replaced the Mooney M20M Bravo in the current company product line.

Mooney and Columbia Aircraft (now owned by Cessna) have frequently traded positions as producer of the fastest production single-engine piston aircraft. Currently, the Acclaim's 242 knot cruise speed at FL250 puts it ahead of the Cessna 400 (formerly known as the Columbia 400) and the turbo-charged version of the Cirrus SR22 GTS. The Cessna 400 is advertised has having a 235 kn (435 km/h) cruise speed, while the Cirrus SR22 GTS has a 220 kn (410 km/h) cruise, both attained at FL250. The Acclaim has retractable landing gear, while the Cessna and Cirrus both have fixed landing gear.

Future developments

In July 2008 Mooney signed a memorandum of understanding with Rolls-Royce to develop a version of the M20 that will be powered by the Rolls-Royce RR500 TP turboprop powerplant. The project is a joint "marketing investigation" and "exploration project" and may not lead to a production aircraft. No milestone dates have been set, including no expected first flight date.

Modifications

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 after-market businesses. Some of these modifications have been incorporated into the factory production models.

Rocket 305
In 1990, Rocket Engineering Corp. of Spokane, Washington, modified a M20K 231 model by replacing the standard turbocharged 210 hp (160 kW) Continental TSIO-360 engine and 2-blade prop with a turbocharged 305 hp (227 kW) Continental TSIO-520-NB and a McCauley 3-blade propeller. This engine and propeller combination had been previously proven on the twin-engined Cessna 340 and Cessna 414. Marketed as the Rocket 305, this variant delivered a 228 knots speed and 1,600 feet/minute rate of climb. This significantly increased performance, but at the expense of higher fuel burn.

The 305 Rocket STC represented a 21⁄2 year certification effort, including 1,000 flight test hours. The 305 Rocket 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 certificated 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 difficulties with demonstrating compliance with the FAA requirements, plus changes to the supplemental oxygen systems in this non-pressurized aircraft. The aircraft will however climb at nearly 1,000 feet/minute above 24,000 (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.

Screamin' Eagle
Midwest M20 Sales & Service created the "Screamin' Eagle" using the long-body M20R Ovation 1 and Ovation 2 and M20S Eagle. The STC increases the maximum propeller RPM from 2500 to 2700 with the installation of a new propeller governor. This change allows the existing engine to produce 310 hp instead of 280 hp at full power. The STC also specifies a Hartzell 3-bladed metal or composite scimitar propeller and increases the gross weight to 3374 lbs on certain older models.

This STC is now licensed to Mooney Aircraft Company and sold as the Ovation 3.

Design

Airframe
With the exception of the wooden wing spars 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 mid 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. Early models use a hydraulic hand pump to control the flaps while 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.

Undercarriage
The tricycle undercarriage 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 nose wheel retracts rearward and the main wheels 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.

Wings
The Mooney M20 has medium aspect ratio tapered wings, incorporating 1.5° of washout and 5.5° of dihedral. On the M20J, navigation and anti-collision 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.

Empennage
The empennage of the Mooney M20 is easily recognizable by its unique tailplane with a vertical leading edge. (The tail looks like it is "leaning forward", but it is actually straight vertical.) The horizontal tailplane, which consists of a fixed stabilizer and trailing elevator, has no trim tabs. The entire tail assembly pivots at the rear of the fuselage to provide for pitch trim.

Fuel system
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.

Ram air
For increased power many M20s also have a ram air 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, giving a greater power output. The turbocharged variants omit this feature as they have their own "power boost" that provides far more increase in manifold pressure.

Constant Speed Propeller

All M20's are single engine aircraft. The power created by the engine is first transferred into torque by engine components, and then into thrust by the constant speed propeller.

The propeller has both forward velocity and rotational velocity, giving a resultant relative airflow. As the forward velocity increases, the angle of attack decreases. To maximize thrust output efficiency, the constant speed propeller is able to maintain an optimum angle of attack of approximately 4°, giving the best lift/drag ratio, by changing the blade angle in flight. In all M20's, the CSU governing system is hydraulically controlled by engine oil and automatically adjusts the blade angle to maintain a specified RPM.

Oil pressure is applied to a piston in the hub of the propeller. As more oil enters the hub, the blades are mechanically (sliding rod and fork arrangement) caused to coarsen, and as oil exits the hub the blade angle progressively becomes finer. In the event of total loss of oil pressure, the blades will become fully fine, and maximum thrust is available. The constant RPM is maintained by the use of a fly-weight assembly. The pilot sets a certain manifold pressure and a corresponding RPM using his controls in the cockpit, and the governor works to maintain that RPM. The fly-weights spin at a speed directly proportional to the engine and are attached to and control the position of the pilot valve. The position of the pilot valve determines whether oil will be entering or exiting the hub, or neither.

Ground Equipment

Towing
While on the ground, it may not always be economical to taxi the Mooney 201 short distances using the engine. A tow bar can be attached to the nose wheel leg and pulled by hand. Safety markers are located on the leg to indicate the maximum degree that the nose wheel can be rotated to avoid damage (14°).

Tie Down
The Mooney 201 should be tied down when not in use, especially in windy conditions. The equipment required is 3 ropes and a nose chock. The aircraft is faced into the wind and the nose chock is put into place. 2 metallic eyebolts are located on the wings, and one on the tail. Ground anchored ropes are tied to these to minimize movement due to wind.

Fuel Requirements
Refueling of the Mooney 201 is done on the ground. Both tanks must be refueled alternately. The minimum grade fuel for operation is AVGAS 100/100LL octane (blue). Refueling can be done using a drum or pump. For the aircraft to operate legally and in balance, weight and loading charts can be consulted to ensure the Mooney remains in the ‘normal’ loading category throughout the flight. The Mooney 201 typically burns 41 litres of fuel per hour at cruise speed. The Mooney comes with a cup actuator which is used to drain fuel from the bottom of the tanks and lines to test for contaminants and water.

Safety record

A comprehensive safety review of Mooney aircraft was conducted by the AOPA Air Safety Foundation from 1982-1991. It was found that in this time 392 Mooney related accidents had occurred, and 75% of these were due to human error. Approximately 6 Mooney aircraft out of every 100 registered in the USA is involved in an accident. According to the review, the most common cause of fatal and serious accidents involving the Mooney aircraft is poor weather judgment. Situations such as inadvertent cloud entry are the cause of 26% of Mooney accidents. Mooney aircraft are involved in twice as many overshoot landings than other aircraft in the same class. This is due to pilot error; approaching the runway faster than the recommended speed of 70 knots. Airspeed cannot be quickly reduced in the Mooney 201 because of the low drag, aerodynamically efficient wings. When airspeed is not sufficiently reduced before the round out, the Mooney 201 tends to stay afloat in ground effect and will balloon. As a result much of the usable runway is wasted and an overshoot is possible. The 3 most recent accidents involving the Mooney 201 in Australia are published in the ATSB archives. These include a mid-air collision due to unauthorized CTA entrance, engine failure resulting in a stall and spin during go around and loss of control at night with unknown causes.

Safety Features

Landing gear
To avoid an inadvertent retraction of the undercarriage while on the ground, an air switch exists behind the ASI. Below 65 knots, the air switch opens the gear actuator circuit, preventing gear retraction. Above 65 knots, dynamic pressure is sufficient to close this circuit allowing the gear to retract. This system, however, can be bypassed in the case of a required take-off and climb below 65 knots. The ‘wheel up’ belly landing is not uncommon in the Mooney 201, be it due to an electrical/mechanical failure or due to pilot error. An aural warning is set to activate whenever the gear is not fully extended and power is set at below 12”MP. This is generally the power configuration on the base leg of landing. An electrical light will advise the pilot whether the gear is up, down or in transit. This can be confirmed by a visual gear position indicator between the co-pilot and pilot seats. The landing gear can also be extended manually in the case of electrical failure by a spring retracted pull cable in the cockpit.

Flight systems
In case of an auto-pilot malfunction, such as auto-pilot or trim run-away, autopilot can be switched off in 3 separate ways. The Autopilot on/off switch, use of the electric trim or by pulling the trim circuit breaker. The aircraft can then be trimmed manually using the trim wheel. The normal static ports on the 201 fuselage that are used to calibrate the altimeter, VSI and ASI may become blocked and give incorrect readings. Therefore an alternate static source exists and can be selected. This is positioned inside the cockpit and gives slightly erroneous readings because of the difference in pressure between the cockpit and outside air.

Cabin
The baggage door doubles as an auxiliary emergency exit. If required, a light plastic covering situated on the inside of the door can be pulled off to reveal a pin. Pulling this pin disables the locking system and the baggage door can be opened from the inside. Seatbelts consist of a lap strap and shoulder harness and must be worn during take-off and landing.

Aircraft on display

The Mooney Super M20E is the aircraft most closely associated with Robin Miller, a famous Australian female pilot known as the "Sugar Bird Lady" for her work in distributing the polio vaccine across Australia. Her aircraft is preserved at Jandakot Airport near Perth, Australia.

Specifications (2007 Mooney M20TN Acclaim)

General characteristics
Crew: one pilot
Capacity: 3 passengers
Length: 26 ft 9 in (8.15 m)
Wingspan: 36 ft 5 in (11.1 m)
Height: 8 ft 4 in (2.5 m)
Wing area: 175.7 sq ft (16.3 m²)
Airfoil: NACA 63-215
Empty weight: 2370 lb (1074 kg)
Loaded weight: 3374 lb (1528 kg)
Useful load: 1004 lb (454 kg)
Max takeoff weight: 3374 lb (1528 kg)
Powerplant: 1× Continental TSI0-550-G Turbo-normalized with twin turbo and dual intercoolers air-cooled, 6-cylinder, horizontally-opposed piston engine, 280 hp (171 kW)

Performance
Maximum speed: 242 knots (278 mph, 448 km/h)
Cruise speed: 237 knots (272 mph, 438 km/h)
Range: 1445 nm (std tanks) (1662 mi, 2676 km)
Service ceiling: 25,000 ft (7625 m)
Rate of climb: 1240 ft/min (378 m/min)
Wing loading: 19.2 lb/ft² (96 kg/m²)
Power/mass: 12.0 lb/hp (0.11 kW/kg)

Last updated February 04, 2010
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Mooney M20".
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