Engineering Innovation
The M-22 Mustang represented a bold leap in general aviation technology under the leadership of designer Ralph Harmon, whom Mooney recruited from McDonnell Aircraft. Harmon's team faced the unprecedented challenge of incorporating pressurization systems into a single-engine piston aircraft, requiring significant modifications to Mooney's proven M20 platform. The fuselage was widened with a six-inch plug to accommodate both the pressurization equipment and provide greater passenger comfort during extended high-altitude flights.
The aircraft's pressurization system enabled operations at 24,000 feet, allowing pilots to climb above most weather while maintaining sea-level cabin pressure for occupant comfort. This capability was complemented by six cowl flaps designed specifically for engine cooling in the thin air of high altitudes, addressing one of the primary technical challenges of turbocharged aviation.
Record-Breaking Performance
On May 23, 1967, pilot Paul Rachael demonstrated the M-22's remarkable capabilities by flying non-stop from New York to Paris in the second production aircraft, christened Spirit of Texas. This transatlantic journey covered Charles Lindbergh's historic route in just 13 hours and 10 minutes, compared to Lindbergh's 33.5-hour flight exactly 40 years earlier. The flight served as both a commemoration of aviation history and a powerful demonstration of the Mustang's long-range capabilities for Mooney's European sales tour.
The aircraft's performance specifications justified such ambitious flights. Powered by the Lycoming TIO-541-A1A turbocharged engine producing 310 horsepower, the M-22 could reach 24,000 feet in under 20 minutes and maintain cruise speeds exceeding 220 knots at altitude. The fuel-injected six-cylinder engine, manufactured by Lycoming Engines, provided reliable operation with overhaul intervals of 1,300 hours or 12 years, essential for the extended flights the aircraft was designed to undertake.
The Manufacturer's Gamble
Mooney Aircraft Corporation, founded by brothers Al and Art Mooney in 1929, had established itself as an innovative force in general aviation by the 1960s. After early bankruptcy in 1930 and resurrection in 1948 in Wichita, Kansas, the company relocated to Kerrville, Texas by the mid-1960s. Mooney had built its reputation on distinctive designs featuring forward-swept tails and efficient aerodynamics, particularly with the successful M20 series that began in the mid-1950s.
The M-22 project represented Mooney's most ambitious undertaking, targeting affluent pilots who demanded airline-like capabilities in a single-engine aircraft. The company invested heavily in the pressurization technology and turbocharged powerplant, creating an aircraft that rivaled light twins in performance while maintaining single-engine simplicity for pilot operations.
Commercial Reality
Despite its technical achievements, the M-22 Mustang faced insurmountable economic challenges. The sophisticated pressurization system, turbocharged engine, and specialized components drove costs beyond the reach of most general aviation buyers. Each aircraft sold at a loss, making continued production financially impossible for the relatively small manufacturer.
Mooney's financial difficulties culminated in bankruptcy, leading to the company's sale to American Electronics Laboratories in 1969, followed by Butler Aviation International in 1970. The new ownership immediately discontinued the M-22 program, focusing on more economically viable aircraft. Production ceased in 1970 after exactly 36 aircraft had been completed, making the M-22 one of the rarest production aircraft in aviation history.
Pilot Experience
Pilots who flew the M-22 praised its stable handling characteristics and impressive high-altitude performance, though they noted heavier control forces compared to unpressurized singles. The aircraft demanded greater pilot proficiency due to its turbocharged engine complexity and pressurization systems, but rewarded skilled operators with exceptional cross-country capabilities. At 75 percent power, the engine consumed 20 gallons per hour while delivering cruise speeds of 230 mph, offering efficiency comparable to much larger aircraft.
The spacious cabin, enlarged specifically for the M-22, accommodated four passengers plus pilot in comfort unusual for single-engine aircraft of the era. The 52-gallon fuel capacity, combined with the engine's efficiency at altitude, provided a practical range of 1,493 miles, enabling non-stop flights across most of the continental United States.
Legacy and Survivors
Today, fewer than 18 M-22 Mustangs remain on civil aircraft registers, representing half of the original production run. Several examples continue flying, maintained by dedicated owners who appreciate the aircraft's unique place in aviation history as the pioneering pressurized single.
The M-22's influence extended far beyond its limited production numbers. The aircraft proved that pressurization in single-engine piston aircraft was technically feasible, paving the conceptual foundation for later successful designs including the Cessna P210 and Piper Malibu. While Mooney's bold experiment ended in commercial failure, it demonstrated the engineering capabilities that would eventually make high-altitude singles a viable market segment, validating the original vision more than a decade after the last M-22 rolled off the production line.