Mooney M20 Series From The Cockpit

The Beginnings . . . and Upheaval

Designer Al Mooney originally formed his company in June 1948 at Wichita to put the single-seat M18 Mooney Mite into production. Operations were moved to Kerrville, Texas in 1953; there M18 production continued, design work on the M20 prototype was completed and the 4-seat aeroplane was put into production in 1954.

By 1964 the M20 was offered in three versions -the Mark 21 (M20C), Master (M20) and Super 21 (M20E). The Mark 21 prototype had flown in September 1961, and the first production aircraft was off on the day of FAA Type Certification, the 7th November 1961. Renamed the Ranger towards the end of the decade, the Mark 21 became the Company’s biggest spinner in their range.

If the sixties were a period of turbulent social change in many parts of the world, for Mooney they were years strewn with a litany of takeovers. The procession started in October 1967, when Mooney merged with Alon Inc. In March 1969, Mooney Aircraft Inc. and Mooney Corporation were sold to American Electronic Industries and renamed the Mooney Aircraft Corporation; November 1969 saw Butler Aviation International achieve 100% stock ownership of Mooney. Butler changed the company name to Aerostar Aircraft Corp in 1970. The identity change came to nought, with the suspension of Aerostar aircraft production in early 1972. Again up for purchase, Republic Steel brought and renamed it Mooney Aircraft in October 1973. The reorganisation heralded a long period of relative stability and product refinement.

Development Consolidation

In 1970 the Model 20 range offered by Mooney consisted of the M20C Ranger, the M20E Chaparral, M20F Executive and the M20U Statesman. These four variants were a mix and match of two engine types and two cabin lengths. The Ranger and Statesman had the 180hp Lycoming 0-360-A1D, and the Chaparral and Executive, the 200hp IO-360-A1A injected engine, in all cases driving a 74 inch Hartzell prop with CSU. The 10-360 installations demonstrated Mooney’s emphasis on detail design for performance and fuel efficiency – they incorporated tuned induction manifolds and ram air recovery induction air inlets. The cabin extension of almost half a metre from 2. 45m to 2. 90m represented a recognition of a market requirement for greater cabin volume; it also afforded a further rear window to be fitted on each side M20 configuration and construction showed a propensity for drag reduction endeavours at an early stage. The wings were of conventional light alloy semi-monocoque construction, with a full span main spar and part-span rear spar (to the flaps outboard ends). With a wing aspect ratio of a moderate value of 7. 4, wing drag is brought down by flush-rivetted and stretch-formed wraparound skins, as well as sealed gap ailerons. Over 70% of the span is electrically operated single-slot flaps.

Fuselage construction consisted of a welded 4130 chrome molybdenum steel cabin with light alloy skinning and a semimonocoque rear fuselage. The light alloy empennage included variable incidence tailplane and fin with upright leading edge and forward-swept trailing edge -the unique Mooney hallmark which survived from suffering fin stall, with the possible exception of the Chaparral, which, with the larger engine power, had a small dorsal installation.

The systems on the M20s were all-electric with the exception of the hydraulic mainwheel brakes. Electric power was provided on the Ranger by a 60A 12V alternator and 35 Ah battery. At an empty weight of 1525Ib with standard equipment, the Ranger took a maximum useful load of 10501b at its MTOW of 2575Ib. Maximum sea level speed was published at 153 knots, and rate of climb there 1000 ft/min. With a fuel tank capacity of 53 USgal, maximum range with VFR reserve for the Ranger was 869nm. The Executive alone had larger tanks a capacity of 64 USgal flying the aircraft 996nm with reserve. With the 10 engine, the maximum SL speed was up to 165 knots, this dropping back. to 161 knots with the cabin extension on the Executive.

A large part of the M20 performance is attributable to low fuselage frontal area – in particular maximum cabin width in these models was 1. 04m (40. 5 in). Thus evolved the Mooney’s reputation for cozy, as opposed to roomy, accommodation. Nevertheless, by January 1970 1,946 M20Cs, 1,337 M20Es and 183 M20Gs had been built.

Era of Performance Refinement

Roy LoPresti joined Mooney in the early seventies to become Chief Engineer and then Vice-President Engineering. LoPresti with a talented aerodynamicist’s eye, continued and expanded upon the M20 series drag reduction programs.

LoPresti’s drag improvements to the Executive resulted in the M20J, first flown in June 1976 and certificated three months later, named the Mooney 201 -the designation being indicative of the aircraft’s top speed in miles per hour. To eke 1 mph per engine horsepower out of the airframe was quite an achievement, but was not the end of the process. Particular attention was given to engine cooling drag.

With the Executive then discontinued, and the Ranger following likewise in 1979, at which time 2,200 had been built, 201s sold extremely well; over 1,250 had been produced by early 1982. The Kerrville works were split over this period between 201 and 231 production -the Mooney 231 (M20K) being a turbocharged version of the 201 also designed in 1976. First flight had been in late ’76 but the Company’s market view was not entirely clear – the certification procedure was not finalised until late 1978. The program was vindicated early and by 1982 661 aircraft had been built.

The 201 is powered by a 200hp Lycoming 10-360-A3B6D. With a fuel capacity of 64USgal the aircraft has a substantial range without reserve of 974nm at 75% power, a result of the admirable cruise speed at this power and 8000ft of 169 knots – providing a mean specific air range of over 15nm per USgal. The basic airframe of the 201 is the same as that of the earlier Executives. Refinements were in the areas of profile and cooling drag reductions. Apart from all the attention given to tidy up the airframe, the 201 configuration has one big factor going for it concerning drag-profile drag is proportional to the frontal area of the aircraft; thus the low frontal area of the M20 is indicative of high performance being an original design objective. Low frontal area comes from having a narrower cabin (maximum internal width 1. 10m, although this figure depends upon the trim style and fitting) and less tall cockpit.

The 201 has a 12volt electrical system, used for instruments, avionics and flap and landing gear operations. The trailing link type landing gear has (unique for its class) rubber block shock absorbers – simple and effective. Retracted, the nose landing gear is covered, whilst the main gear is faired with outer doors only.

The 231 is powered by the Continental TSIO-360-GB turbocharged flat-six of 210hp. Fuel capacity is increased to 76 USgal, expanding the range envelope to 1182nm without reserve at 55% power cruise, for which the cruise speed at FL240 is 162 knots. The engine installation necessitated an increase forward in fuselage length of a quarter metre. Empty weight went up 130lb to 1800lb standard, but load capability was recovered with a 160lb increase in MTOW to 2900lb. Nevertheless, the useful load with full tanks was down to 626lb. For a fully IFR-equipped aircraft this will reduce to about 500lb, enough for three lightweights with no baggage. The 201 is in roughly the same position with full tanks, calling for fuel load control flying smaller segments with seats full.

The 201/231 models as evidence of the right formula were changed little for about eight years from the time of initial marketing-yearly models changing only in equipment fits, trimming and paint schemes.

Through Recession

With the sales crash looming in the early ’80s, Mooney turned attention to a Malibu/P210 competitor and designed and flew the Mooney 301-an entirely new aeroplane with a Bruce Holmes-type cruise-optimised wing area, Eppler engineered wing section and a 360hp TIO-540-X27. However production funds were not forthcoming. LoPresti was promoted President of Mooney and in 1984 Republic Steel merged with LTV and the ownership of Mooney Aircraft was taken over by a number of private investors. In Spring 1985, Paris based Euralair jet charter and FBO President Alex Couvelaire and Michelle Seydoux, President of MSC, jointly brought 70% of Mooney Aircraft, with Lake Aircraft holding the remaining 30%.

As Cessna’s and Piper’s singles production was suspended and stocks sold, Mooney’s output also was hit – but its percentage of the SE/retractable LG market lifted.

In 1986 the 201 was modded in two ways-on the one hand its equipment was trimmed down in an effort to keep the price down and sales up (various items of non-essential equipment were removed, i. e. moved over from the standard to optional columns) and the 201LM Lean Machine came on the market as an IFR aircraft for under US$100,000.

On the other hand the airframe was refined to reduce drag further particular with the introduction of new LG doors, now fully enclosing the retracted MLG and wheels, altered engine cowl flaps, and new wingtips with faired lights. Also a new 28 volt electrical system was installed, and preselect flap control with a higher approach flap (15 deg) limit speed of 132 knots, up from the previous 115 knots. The aircraft, in recognition of the four additional mph of top speed is designated the Mooney 205. It is fitted with the interior trim of the 252TSE (see below).

A New Turbocharger

The 231 was dropped in 1985 to be replaced by the Model 252TSE (Turbo Special Edition). With a new engine installation having a much wider full power rating envelope, this aeroplane was introduced with the market strategy of entering the Malibu/ P210 sector ‘cheaply. The new engine, a Continental TSIO-360- MB-1 differs from that previously installed, primarily by the inclusion of an AiResearch TE04 Turbocharger with automatic wastegate and an intercooler. The intercooler assists power production so that maximum continuous power is up from 75% at 17000ft (in the 231) to 78% at 27,000ft-resulting in a maximum cruising speed increase to 200 knots.

The new engine is not without cost to the airframe: fitting the slightly heavier engine installation displaces the empty aircraft centre of gravity slightly too far forward. To maintain it in the appropriate position, ballast weights have been added to the tail. For this, amongst other reasons the 252 can probably be considered as achieving the final evolution from a very long standing airframe. But then again, you never know, although Mooney’s next design project is the completely new turbine single, the TBM700, a joint personal/business aircraft project with Socata of France.

At 20,000ft in ISA +10°C air, the turbocharged and intercooled-engine can hoist the 252 along at 200 knots, using 12. 6 USgal/hr. With a useful load capacity of 860lb, half the seats can be occupied and 30lb of baggage carried with full fuel (72 USG). The airplane of course lacks pressurisation, a big drawback in comparison with the Malibu or P210; the relatively cramped interior and need for an oxygen system are pointers to the probability that the 252TSE would be most endearing to the owner who flies him or herself with a need for economy but with little need for much passenger accommodation. The 252 is offered with a yaw damper (KFC 150 flight control system) and optional Precise Flight speed brakes (wing upper surface spoilers).

Although the Mooney M20 is designed for performance, airborne it makes few concessions to good handling qualities. The dihedral, at 5% deg is on the low side and apparently complicated compliance with the static lateral stability requirements. Certificated for the Ranger was the Mooney Positive Control System, developed with Brittain, the vacuum autopilot specialist. In the system a tilted rate gyro sensor picked up roll or yaw deviations and directed vacuum pressure to the aileron and rudder vac servos to produce coordinated corrective action and restore the aircraft to straight and level. This complex wing levelling system was replaced by interconnected ailerons and rudder.

Market Prices

A mid-seventies VFR or NVFR Executive is listing for about $45,000 on the local market. With a wider resale market 201s, trade at considerably higher prices, from $75-80,000 for a 1977/ 78 model with LIFR/IFR avionics to over $100,000 for early 1980s models; whilst for Mooney 231s over this period, the list price covers a range of about $95-120,000.

New American light planes are still not selling in any numbers in Australia. From the M20 selection, the 201LM probably has the greatest chance of moving: to compare the prices Mooney’s Australian distributor, who has been dealing with Mooneys for many years offers a new 201LM with a warranty for about $165,000-a reflection as always upon the dollar exchange rate.