Number 64 of 100 in 100: The Mitsubishi MU-2 🛫

Conceptualization:

In the early 1960s, the aviation industry was buzzing with the demand for fast, efficient, and versatile turboprop aircraft. Pilots, private business owners, and corporate aviation departments were on the lookout for an aircraft that could deliver the power and speed of a jet but with the fuel efficiency and operating costs of a propeller-driven plane. This was a period where the landscape of aviation was shifting; people wanted more than just reliability—they needed performance, versatility, and the ability to access smaller airfields.

Mitsubishi Heavy Industries (MHI), with its deep roots in aviation engineering and experience in both military and civilian aircraft production, saw this as the perfect moment to step in. The goal was clear: create a twin-engine turboprop that could outperform its competitors, offer robust reliability, and remain adaptable enough for various uses, from corporate travel to cargo and special missions. The Mitsubishi MU-2 was born out of this vision, crafted with the needs of demanding pilots and operators in mind.

Original Design:

The Mitsubishi MU-2's design was bold and innovative, setting it apart in a world dominated by more conventional turboprop designs. One of the first things you notice about the MU-2 is its high-wing configuration that contributes to its impressive speed, giving it a stable and smooth ride even in turbulent air. This design choice wasn't just about aesthetics; it was meant to make the MU-2 efficient and compact, ideal for operations in and out of smaller airports.

Powering this unique aircraft were Garrett TPE331 turboprop engines, known for their robust performance and fuel efficiency. This made the MU-2 capable of impressive climb rates and speeds that outpaced many of its competitors. The high-wing configuration not only provided excellent visibility for pilots but also improved ground clearance for operations on rough or less-developed runways. To top it all off, the MU-2 had a pressurized cabin, allowing it to soar at higher altitudes comfortably, which was a luxury for corporate and long-distance flyers. The interior was spacious and could be configured to suit various needs, whether for executive seating or cargo transport, making it a true multitasker in the sky.

Photo Credit: airliners.net - Andre Wadman

Principal Designer:

The MU-2 was the product of Mitsubishi Heavy Industries, an engineering powerhouse with a legacy that stretched back to the early days of aviation. The team behind the MU-2 drew from deep pools of experience, having been involved in military aircraft production, including the legendary A6M Zero fighter from World War II. This background in designing high-performance, reliable aircraft played a significant role in shaping the MU-2’s design philosophy.

Post-war restrictions limited Japan’s aircraft manufacturing capabilities for a time, but by the mid-1950s, the industry began to rebound. The MU-2 project was MHI’s first major civilian aircraft venture after the war, embodying their ambition to reclaim a prominent spot in the global aviation market. The engineering team behind the MU-2 leveraged their expertise from military aviation to produce an aircraft that was powerful, rugged, and innovative. Their work on the MU-2 would later feed into other projects, such as the MU-300 Diamond business jet, demonstrating that the same team had a knack for creating aircraft that stood the test of time.

Production Run:

The MU-2 first took to the skies on September 14th, 1963, and its production spanned over two decades until 1986. During this time, Mitsubishi Heavy Industries managed to produce 704 units, an impressive feat for an aircraft in its class. The initial production saw a steady flow as the aircraft gained traction for its high-speed capabilities and unique design, appealing to both civilian and military operators.

In 1965, Mitsubishi collaborated with Mooney Aircraft to assemble and market the MU-2 in the U.S., utilizing Mooney's facility in San Angelo, Texas. However, financial difficulties led Mitsubishi to take over the facility, where production continued through the 1970s and early 1980s. The production remained relatively consistent throughout its run, driven by steady demand for its distinctive performance and versatility. By the time production ended, the MU-2 had carved out a niche as a powerful and reliable aircraft for both business use and in specialized mission roles.

Evolution:

Throughout its production run, the MU-2 underwent significant evolution to enhance its capabilities and address feedback from operators. The initial models like the MU-2A and MU-2B set the foundation with their robust engines and streamlined design. Models such as the MU-2F and MU-2G, included more powerful versions of the TPE331 engines, further boosting performance. Later, the long-body variants like the MU-2K and MU-2M expanded cabin space and payload capacity, making them versatile for larger groups and longer missions. The final production models, including the MU-2J and MU-2N, featured modern avionics and structural improvements that reinforced the airframe and increased safety. These continuous updates kept the MU-2 competitive and improved its handling, which was especially appreciated by experienced pilots who enjoyed the aircraft’s power and responsiveness.

Photo Credit: airliners.net - David Price

Specifications:

Mitsubishi MU-2L Specifications:

General Characteristics:

• Crew: 1 or 2 pilots
• Capacity: 4–12 passengers
• Length: 12.01 m (39 ft 5 in)
• Wingspan: 11.94 m (39 ft 2 in) including tip tanks
• Height: 4.17 m (13 ft 8 in)
• Wing area: 16.55 m² (178.1 sq ft)
• Aspect Ratio: 7.71:1
• Airfoil: root: NACA 64A415; tip: NACA 63A212
• Empty weight: 3,433 kg (7,568 lb)
• Max takeoff weight: 5,250 kg (11,574 lb)
• Fuel capacity: 1,388 L (367 US gal; 305 imp gal) maximum usable fuel
• Powerplant: 2 × Garrett TPE331 -6-251M turboprop engines, 579 kW (776 hp) each
• Propellers: 3-bladed Hartzell HC-B3TN-5/T10178HB-11 fully feathering reversible constant-speed propellers, 2.29 m (7 ft 6 in) diameter

Performance:

• Cruise speed: 547 km/h (340 mph, 295 kn) at 4,175 kg (9,204 lb) at 4,575 m (15,010 ft) maximum
• Economical cruise speed: 483 km/h (300 mph; 261 kn) at 4,175 kg (9,204 lb) at 7,620 m (25,000 ft)
• Stall speed: 185 km/h (115 mph, 100 kn) flaps down (Calibrated airspeed)
• Range: 2,334 km (1,450 mi, 1,260 nmi) at 7,620 m (25,000 ft) with full wing and tip tanks including 30 minutes reserve
• Service ceiling: 9,020 m (29,590 ft)
• Rate of climb: 12.0 m/s (2,360 ft/min) at sea level
• Take-off run to 15 m (50 ft): 661 m (2,169 ft)
• Landing run from 15 m (50 ft): 573 m (1,880 ft)

In Comparison to Other Aircraft in its Class:

In the competitive landscape of 1960s and 1970s turboprops, the Mitsubishi MU-2 stood out for its remarkable speed and impressive climb performance, often surpassing many of its peers with cruise speeds up to 295 knots and a climb rate around 2,360 feet per minute, thanks to its powerful Garrett TPE331 engines. Its high wing loading contributed to a stable and smooth ride at higher speeds and in turbulent conditions. However, this design feature also brought challenges, especially during low-speed handling, which demanded specialized pilot training to manage safely. The MU-2's effective STOL capabilities allowed it to operate from shorter runways, making it more versatile than typical turboprops.

Compared to the Beechcraft King Air 90, the MU-2 had a more efficient climb, but the King Air 90 offered a more spacious cabin and was generally considered easier to fly due to its traditional ailerons and more forgiving handling. The Fairchild Swearingen Merlin, with its cruise speed of up to 300 knots, was faster and had more conventional handling, which appealed to many pilots looking for predictability and ease.

The MU-2 was attractive for operators who prioritized high performance and versatility, making it a solid choice for those willing to trade some cabin comfort for speed and operational flexibility. However, its complex handling profile and the need for specialized training, highlighted by the FAA's mandated training programs in 2008 (SFAR No. 108), underscored its demanding nature. For experienced pilots who invested in understanding its flight characteristics, the MU-2 offered unmatched capabilities that made it unique in its class.

Performance:

Mitsubishi MU-2 Performance Envelope

V-Speeds:

• V_MO (Maximum Operating Speed): 250 knots indicated airspeed (KIAS)
• V_Y (Best Rate of Climb Speed): Approximately 140 KIAS
• V_YSE (Best Rate of Climb Speed with One Engine Inoperative): Approximately 130 KIAS
• V_MC (Minimum Control Speed with One Engine Inoperative): Approximately 98 KIAS
• V_REF (Landing Reference Speed): Approximately 115 KIAS
• V_FE (Maximum Flap Extended Speed): 130 KIAS
• V_LO (Maximum Landing Gear Operating Speed): 150 KIAS
• V_LE (Maximum Landing Gear Extended Speed): 175 KIAS

G-Load Limitations:

• Flaps Up: +3.17g to -1.27g
• Flaps Down: +2.0g to 0g

Performance Assessment:

The Mitsubishi MU-2 is a high-performance turboprop that shines with its powerful capabilities, making it both an excellent training platform and a reliable option for personal aviation—albeit with unique challenges. For training, the MU-2’s fast cruise speed of 295 knots and impressive climb rate helps pilots transition from smaller aircraft to turboprops or jets. Its short takeoff and landing (STOL) capabilities are perfect for teaching short-field techniques. For personal aviation, the MU-2’s speed, range, and robust build make it a great choice for cross-country flights, appealing to owners who value reliability and operational flexibility, with its cabin able to switch between passenger and cargo configurations. However, the MU-2’s high wing loading and unique roll control mean that pilots must undergo specialized training to handle it safely—its handling is different from more conventional aircraft. The FAA-mandated training programs highlight the importance of mastering its flight dynamics, especially during emergencies. While the MU-2 is rewarding for those who are well-trained and experienced, it demands commitment to learning and practice to ensure safe operation.

Photo Credit: airliners.net - Juliano Damasio

Safety Record:

The MU-2’s safety record has been a rather hot topic in aviation circles, especially when a total of 170 documented crashes have occurred as of May 2024. The aircraft’s high wing loading and unique control surfaces mean that pilots need to be well-trained and highly proficient. Without proper handling knowledge, issues can arise, particularly in situations requiring rapid decision-making or emergency responses. 

Over time, it became clear that insufficient training was a major factor in many incidents. The FAA took action by mandating a special training program for all MU-2 pilots in 2008, a move that dramatically improved the safety record. This shift highlighted that the MU-2 wasn’t inherently unsafe; it just demanded pilots who understood its specific needs. When flown by well-trained pilots, the MU-2 proved to be reliable and responsive, with accident rates aligning more closely with its peers, like the Beechcraft King Air and Swearingen Merlin.

Conclusion:

The Mitsubishi MU-2 is not just another aircraft; it’s a testament to the daring innovation of its time. Its powerful engines, compact design, and advanced engineering allowed it to perform in a league of its own. While its handling characteristics presented challenges that required specialized training, those who mastered the MU-2 often fell in love with its capabilities. The aircraft’s evolution over two decades, from its early models to the long-body variants with upgraded avionics, showed Mitsubishi’s commitment to refining the design and meeting the needs of its pilots and operators.

Today, the MU-2 continues to fly with distinction, thanks in part to the FAA’s training mandates that have helped ensure it is operated safely. For pilots willing to invest the time and effort, the MU-2 offers a flying experience that few other turboprops can match. It remains a reminder that innovation and pilot skill, when combined, create an exceptional aircraft that can stand the test of time. Whether you’re flying it for business or personal use, the MU-2 delivers a sense of power and precision that is truly unique.

Photo Credit: Aero Corner - GeorgeM757

Bibliography:

Mitsubishi MU-2 Official Page

Federal Aviation Administration (FAA)

Aircraft Owners and Pilots Association (AOPA) – Mitsubishi MU-2 Fact Sheet

AvWeb – Mitsubishi MU-2

Wikipedia – Mitsubishi MU-2

Plane & Pilot Magazine – Mitsubishi MU-2

Airliners.net – Mitsubishi MU-2

Essco Links:

Mitsubishi MU-2

Garrett TPE331

Beechcraft King Air

Swearingen Merlin