Microsoft Flight Simulator Pilots can now fly one of aviation’s greatest innovation icons.
A MONUMENT TO THE AVIATION DEFICIENCY
The Dornier Do 31 is a jet-powered, vertical take-off and landing (VTOL) experimental military aircraft developed by the West German aviation manufacturer and is historically known as the only jet-powered VTOL airliner/transport aircraft ever developed and flown. Although Dornier only produced three experimental prototypes and never entered series production, the Do 31 remains a lasting monument to aerospace ingenuity.
BORN FROM THE COLD WAR IMPERATIVE
The distinctive Do 31 grew out of an ambitious Cold War initiative by the West German military to create a highly resilient air force. An initial attack by the Soviet bloc focused on air bases and airstrips across West Germany, grounding its aircraft. To counter this threat, the West Germans hatched a plan in the early 1960s to create a new air force consisting primarily of jet-powered VTOL aircraft. Such aircraft could operate from traditional air bases, expeditionary airfields, or roads and highways, including highways – any small piece of concrete or asphalt would work.
The West German military’s plan included three VTOL aircraft: a fighter/interceptor: the EWR VJ 101; a ground attack platform: the VFW VAK-191B; and a large multi-role aircraft that could transport troops and cargo.
AN TECHNOLOGY MIRACLE
While helicopters were particularly useful for military operations in the early 1960s, their speed and carrying capacity were limited. However, the development of a jet-powered transport aircraft presented engineers with enormous hurdles such as generating and controlling sufficient thrust to lift an aircraft vertically, bring it into level flight and then land it vertically.
By the early 1960s, companies interested in operating jet-powered VTOL aircraft had proven with experimental models that the concept could work. The Short SC.1, developed by the British aviation company Short Brothers, completed its first flight on May 26, 1958. The Short SC.1 was followed by the first flight of the British Hawker Siddeley P.1127, the forerunner of the Hawker Siddeley Harrier, the world’s first production VTOL fighter jet. Both were technical breakthroughs that took years to develop. The transport aircraft that the West German military envisioned would be much larger, dramatically increasing the complexity. Dornier, famous for its flying boats and airliners, took on the ambitious challenge in February 1962 when the company and the West German military officially launched the project, designated Do 31.
While Dornier had never built a VTOL aircraft, the company’s engineers had gained experience with short take-off and landing (STOL) exercises with their Do 29. This aircraft, which made its maiden flight at the end of 1958, was a twin-engine, piston-engined, high-wing experimental aircraft that used tilting engine-propeller systems to increase lift for takeoff. The jet-powered Do 31, intended to carry up to 36 combat-laden troops, 7,700 pounds of cargo, or a combination thereof, proved far more complex. This required the company to develop some of the most advanced aviation technologies to date, including novel engine designs, high-strength airframe components and an innovative flight control computer.
Dornier built three airframes with the group designation Do 31 E (“E” for “Experimental”): the Do 31 E1, the Do 31 E2 and the Do 31 E3. The E1 and E3 were flying prototypes, while the E2 was a ground-based testbed.
The Do 31 featured a high-mounted main wing, a cruciform tail, a spacious fuselage with a loading ramp system and retractable tricycle landing gear. Its main source of propulsion: two Rolls-Royce Pegasus BE.53/2 turbofan engines, each capable of producing up to 15,500 pounds of thrust. Each Pegasus was housed in a nacelle, one under each side of the main wing, and thrust from each was directed through four rotating exhaust ports called thrust vectoring nozzles. For supplementary thrust and redundancy purposes – should one of the Pegasus engines fail mid-flight – Dornier developed wingtip-mounted secondary thrust systems. Each wingtip featured a nacelle that housed four vertically oriented rolls.
Royce RB-162-4D turbojet engines; Each engine could produce up to 4,400 pounds of thrust, for a total of 17,600 pounds of thrust per wingtip. In total, the Do 31 was powered by ten engines with a total thrust of 66,200 pounds. Few other aircraft in history had ten or more engines, including Dornier’s Do X, a flying boat powered by 12 piston engines.
To ensure control of the Do 31 during all flight modes, Dornier developed a highly critical hybrid analog-digital computer, the DO-960. The aircraft would simply be too unstable to function without a proper flight computer that could continuously solve a series of complex equations to maintain controlled flight. Digital computer technology and integrated circuit design were in their infancy at this time and were not fast enough to carry out the specific solutions required (the microprocessor had yet to be developed). Dornier engineers solved this immense challenge by developing a novel computer system that combined aspects of analog computation with components of digital computation.
The DO-960 ensured the aircraft’s stability by taking into account the pilot’s inputs and the flight surfaces, the power output of each of the aircraft’s ten engines, the orientation of its thrust vectoring nozzles, and the amount of bleed air directed to the nozzles in the aircraft’s tail was, controlled. The Do 31 took off and hovered using the downward thrust of the Pegasus engines combined with the thrust of its wingtip turbojets. It then went into horizontal flight by rotating the thrust vector nozzles of the main engine backwards.
The DO-960 remains one of the most remarkable computer developments in history and a brilliant example of technological innovation born out of necessity. Although hidden within the aircraft’s unique shape, the computer was one of the Do 31’s most important and notable features.
A NEW BREED TAKES FLIGHT
After years of development and ground testing, the Do 31 completed its maiden flight in early 1967. The first prototype airframe, the Do 31 E1, took off on February 10, 1967, powered only by its two main engines. In July 1967, the Do 31 E3 took to the sky with all ten engines on and performed a hover. The aircraft flew increasingly complex and demanding operations during successive tests over the following months, including reverse turns in hover and rolls in level flight. The demonstrations were not only the first flights of a new aircraft, but also the first use of an entirely new type of aircraft, a jet-powered VTOL transport. The Do 31 thrilled spectators at air shows and set several flight records for its class – of which it was the only member.
Despite the successes and prospects for commercial adoption in addition to military use, the Do 31 was abandoned in the early 1970s. The concept of a jet-powered VTOL air force proved too costly and complex to implement. It remains the first and only jet-powered VTOL transport ever to fly.
Piloted by two pilots, the Do 31 had a range of 1,120 miles, a service ceiling of 35,100 feet above sea level and a climb rate of 3,780 feet per minute. The aircraft flew at a speed of 348 miles per hour and a maximum speed of 377 miles per hour.
NOW AVAILABLE FOR MICROSOFT FLIGHT SIMULATOR PILOTS
The Microsoft Flight Simulator Dornier Do 31 has been expertly recreated for aviators around the world to enjoy. Experience the thrill of vertical takeoff, transition to high-speed forward flight, and subsequent precise hovering in this masterpiece of aviation technology. Heaven is calling!
The Dornier Do 31 offers seven liveries: E1 Experimental, E3 Experimental, Olive Green, Green Camouflage, Marine Search & Rescue, Xbox Aviators Club and Aviators Club. It’s available now for $14.99.
Microsoft Flight Simulator is available for Xbox Series X|S and PC Xbox Game Pass, PC Game Pass, Windows and Steam as well as on Xbox One and supported lower spec mobile phones, tablets and PCs via Xbox Cloud gaming. The latest information about Microsoft Flight Simulator can be found here set on @MSFSOfficial on X (formerly Twitter).
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