Oblique Wings and Flying scissors NASA Ames Dryden-1 AD-1

During and after World War II, aviation technologies began to develop at an extraordinary pace. In just a few years, travel evolved from noisy and uncomfortable propeller planes to luxurious and fast jet airliners. During this period, aviation technologies were advancing so rapidly that by the time a design was ready to fly, it could already be obsolete. This was also an era where some of the strangest designs in aviation history were attempted. One such innovation from this time was the concept of oblique wings, developed to provide ideal aerodynamic properties at different speeds. This concept promised to optimize the lift for supersonic speeds in one swift motion, like cutting with scissors, and it proved to be true to its claims. Welcome to Extraordinary Aviation Designs. In this video, we will discuss the oblique wing design which claimed to revolutionize wing technology and its first flying example, the AD-1. 40 years after the Wright brothers made their first powered flight, aircraft had already reached speeds of 1,000 kilometers per hour. The capabilities and speeds of aircraft increased significantly due to World War II, but once speeds reached 1,000 kilometers per hour, it was as if they hit a wall. Controlling aircraft at high speeds became extremely difficult. Airframes were wearing out and even breaking due to the loads they endured. Engineers and pilots discovered that these issues occurred between speeds of 1,000 kilometers per hour and 1,200 kilometers per hour. In this zone, also known as the transonic region or the sound barrier, aircraft of the time could not fly safely or controllably. The reason for this was that as the speed of sound was approached, the nature of flight changed and the straight wing designs used until then became inadequate. In the mid-1930s, research to solve this problem led to the discovery that swept-back wing designs could prevent the control issues encountered at higher speeds. After this discovery, aircraft speeds began to rise again. Planes with swept-back wings could now fly supersonically with ease and maintain better control during maneuvers. However, swept-back wings had their own set of problems. Aircraft with these wings had difficulties at low speeds, especially during takeoff. Aircraft engineers began working on different methods to design planes that could perform safely and efficiently at both low and high speeds. The most prominent concept was variable geometry wings. In this design, wings were mounted on pivots and could change angle and surface area depending on the speed of the aircraft. While this technique helped with control and lift, it also introduced new problems. The first problem was that when the wings changed position, the center of lift shifted as well, disrupting the plane's balance in flight. The second issue was that the mechanisms needed to change the position of the wings quickly and safely in flight were large, heavy, and expensive. These moving parts had to be made from high-strength materials like titanium. Additionally, the aircraft had to be enlarged to accommodate these heavy bulky structures, which meant bigger engines and increased fuel consumption. The search for a solution that could provide adequate lift at all speeds wasn't overly complex and wouldn't increase the size or fuel consumption of the plane began in 1942. The first full-scale design in this area was the P-202 aircraft, developed during World War II by the German aircraft manufacturer Blom & Voss, known for designing unusual aircraft. The design didn't reach the prototype stage during the war, but it provided calculations proving the feasibility of such an aircraft. In the 1950s, Robert Thomas Jones, an engineer who gained recognition for his delta wing designs at the National Advisory Committee for Aeronautics, NAA, which later became NASA, started researching the benefits of the oblique wing while studying wing designs that provided optimal maneuverability and lift at both low and high speeds. In this design, the wings could be easily providing the necessary lift. Normally, wings designed for supersonic flight struggle to generate the required lift at very low speeds, such as during takeoff. That's why supersonic planes like the Concorde had to rely on their engines to generate sufficient thrust while on the runway, leading to high fuel consumption. The oblique wing design, however, could avoid these issues by adjusting the wings to a perpendicular position during takeoff. At supersonic speeds, the oblique wing system could rotate up to 60 degrees, providing the optimal wing angle and surface area for speeds up to Mach 1.4. To observe how this design would behave in real life, NASA began testing a remotely controlled model of the concept. Meanwhile, wind tunnel tests were also conducted on a commercial design called developed in partnership with Boeing. The unmanned aircraft and wind tunnel tests showed that the wing's performance at lower angles during flight was successful. However, at higher angles, the aircraft had difficulty maintaining straight flight, pulled slightly to the right, and tended toward a 7 degree turn. If this turn wasn't corrected by a pilot or a flight control computer, the plane would eventually enter a spiraling descent. Despite these control problems, the advantages of the design were significant enough that NASA decided to build a manned test aircraft. The AD-1 design, which began in 1976, would measure the flight responses of the so-called scissor wing design. To cut costs, since NASA couldn't allocate a large budget for a new wing structure, the designers built the fuselage from carbon fiber and plastic. The cockpit resembled that of a glider, and even the landing gear was made fixed to save on costs. The aircraft, which made its first flight on December 21, 1979, completed 79 flights throughout its mission. During these tests, it was found that the aircraft maintained balance when the wings were rotated up to 45 degrees. However, at angles greater than 45 degrees, the plane started experiencing the same balance issues observed in the earlier unmanned tests and wind tunnel experiments. It was concluded that these instabilities, which could be challenging for a pilot during straight flight and maneuvers, could be solved with a flight control computer featuring fly-by-wire technology. After these tests, which were conducted at relatively low speeds of around 320 kilometers per hour, NASA sought support to test the performance of the oblique wing concept at supersonic speeds. The U.S. Navy stepped in, looking to replace its F-14 planes operating on aircraft carriers. The Navy believed oblique wing planes could be used both for air defense and as aerial refueling tankers. To test this, the Navy joined the project by offering one of its F-8 Crusader aircraft. In 1984, the two organizations agreed that NASA would convert the Navy's F-8 into an oblique wing structure to test its performance at supersonic speeds. According to the plan, the developed aircraft would make its first flight in 1991. However, in 1986, the Navy withdrew its support due to budget cuts. NASA, unable to finance the project alone, had to halt the program. Having lost military backing, the scissor wing concept didn't attract interest from the civil aviation industry, which preferred conventional designs. AD-1 took its place in aviation history as a special aircraft that tested a promising concept. Thank you for watching Extraordinary Aviation Designs. If you found our video helpful, please like and share. You can support our channel by clicking the thanks button or joining as a member. And don't forget to subscribe so you won't miss our videos on extraordinary designs in aviation history.