Welcome to This Date in Aviation History, getting you caught up on milestones, important historical events and people in aviation from April 1 through April 4.

April 1, 1939 – The first flight of the Mitsubishi A6M Zero. The Japanese surprise attack on Pearl Harbor on December 7, 1941 served as a deadly wakeup call to the United States, as Japanese plans for the expansion of their empire came home to the American people. But that rude awakening also extended to the US Army Air Forces and US Navy, who came face to face with the remarkable A6M Zero for the first time, an aircraft that was clearly the best fighter in the Pacific at the time. In early 1937, the Imperial Japanese Navy issued specification 12-shi to develop a new fighter to replace the Mitsubishi A5M (allied reporting name Claude), which had the distinction of being the world’s first ship-based monoplane fighter. The requirements in 12-shi were rigorous, and included a top speed of 370 mph, a high rate of climb, heavy armament (two 20mm cannons, two .303 caliber machine guns, two 130-pound bombs), and enough range to cover the vast distances of the Pacific Ocean. Lead Mitsubishi designer Jiro Horikoshi realized that the only way to design a fighter to these specifications was to make it as light as possible. so, in order to save weight, the Type 0 Carrier Fighter as it was called was constructed of a new, top-secret aluminum alloy, had no armor to protect the pilot or engine, and no self-sealing fuel tanks. This made for a fighter that possessed excellent aerobatic and dogfighting characteristics, but also one that caught fire easily and could not withstand the pounding from heavier American fighters. The Zero (also known to the Japanese as Rei shiki Kanjō sentōki, or Rei-sen for short) entered service in 1940 fighting against obsolete Chinese biplane fighters during the Second Sino-Japanese War where it quickly gained a reputation as an unbeatable dogfighter. As the Japanese expanded into areas of the British and Dutch empire, the Zero came up against some of the best Allied fighters of the time, and even provided a serious challenge to the Supermarine Spitfire which, while faster, was no match for the Zero in a turn. The Zero also far outclassed all American fighters of the early part of the war.

The A6M3 Zero of Hiroyoshi Nishizawa, one of Japan’s top aces of WWII

However, American pilots soon developed new techniques for combating the Zero. Flying a Brewster F2A Buffalo or Grumman F4F Wildcat into a one-on-one dogfight with the Zero was practically suicidal, but high speed passes from above and the development of the Thatch Weave helped the Allies to fight on a more even footing. Though the Zero had earned an aura of invincibility early in the war, its mysteries were finally unlocked when an almost intact A6M was recovered from the Aleutian island of Akutan in 1942 after its pilot was killed in a crash landing. The fighter was shipped back to the US, repaired, and its flight characteristics were thoroughly analyzed. Testing showed where the Zero’s weaknesses lay, such as the propensity for its ailerons to freeze up at speeds above 200 knots, and a carburetor that caused the engine to quit in certain negative G maneuvers. These discoveries led to specific tactics that helped the Allies defeat the Zero in combat. Throughout its life, the Zero was consistently updated, most significantly with more powerful engines, a supercharger, shortened wings that improved roll rates, redesigned ailerons and trim tabs. A new exhaust system also provided a modicum of thrust. Ultimately, nearly 11,000 Zeros of all variants are produced. However, the Zero’s dominance was short lived, as Allied designs quickly improved. By the second half of the war, American fighters such as the Grumman F6F Hellcat and Vought F4U Corsair were every bit the match for the Zero. The war had also taken a heavy toll on experienced Japanese pilots who could never be replaced. By the end of the WWII, the Zero was relegated to Kamikaze attacks against Allied shipping in the Pacific, an ignominious end for such a remarkable aircraft. (Photo by Marc Grossman via Wikimedia Commons)

April 1, 1935 – The first flight of the North American T-6 Texan. In baseball, it’s rare to hit a home run your first time at bat. But that’s exactly what happened to North American Aviation with the T-6 Texan. Back in 1935, North American debuted the model NA-16, the first trainer aircraft they had ever designed. and in 1937, North American submitted the aircraft in response to a US Army Air Corps request for a “Basic Combat” aircraft. The USAAC initially ordered 180 of the BC-1 variant, which had retractable landing gear and provisions for up to three .30 caliber machine guns. Early models were powered by a single Wright R-975 Whirlwind radial engine, which gave the BC-1 a maximum speed of 170 mph. North American experimented with a host of modifications including redesigned wings, different engines, fixed and retractable landing gear, open and enclosed cockpits. They also experimented with various rudder shapes before settling on a recognizable triangular shape that helped prevent a loss of control during maneuvers with a high angle of attack. It was the BC-2 variant of the Texan, now called AT-6 to signify its role as an advanced trainer, that received its iconic shape and name, with squared wingtips and triangular rudder. The addition of a more powerful Pratt & Whitney R-1340 Wasp radial increased the Texan’s top speed to just over 200 mph, and the USAAC ordered more than 1,500 of that model, designated AT-6A. North American also produced 400 aircraft for export to the RAF where it was known as the Harvard I, and a handful for the US Navy, where it was known as the SNJ-1. The Texan became the primary trainer for the USAAF, where it proved to be an extremely reliable and sturdy aircraft. It was responsible for training the vast majority of pilots who flew during WWII, providing student pilots with a more powerful and maneuverable aircraft as they transitioned from basic trainers to frontline fighter aircraft. The Texan had excellent flight characteristics, and could perform all the necessary aerobatic maneuvers that combat pilots needed to learn, including dogfighting, dive bombing and ground attack. The armed AT-6B variant was used for gunnery practice, and armed Texans saw actual combat in low-intensity conflicts following WWII. By the time production ended, 15,495 Texans had been built, and they were in service in 34 countries around the world. The Texan remains a workhorse today, where it is popular on the air show circuit and it forms the basis for numerous historical squadrons and aerobatic teams. Others have been modified to mimic Japanese Zero fighters for historic reenactments and roles in movies. And the Reno Air Races in Reno, Nevada still maintains a unique racing class for Texan and Harvard aircraft. (US Air Force photo)

April 4, 1957 – The first flight of the English Electric Lightning. At the beginning of the Cold War, and before the advent of the intercontinental ballistic missile, the long-range bomber was the primary means by which one nuclear power might attack another, and defense against these bombers relied on the use of interceptor aircraft. An interceptor of the 1950s was essentially a missile-armed fighter that could fly at great speed to meet the incoming bombers and shoot them down as far away as possible from their intended targets. As there was no expectation that the interceptor would have to engage in a dogfight with other fighters, extreme maneuverability was sacrificed for all out speed. Development of the Lightning interceptor began all the way back in 1947, when English Electric, maker of the brilliant Canberra bomber, was awarded a contract to develop a supersonic research aircraft. Designers decided to employ a radically swept wing, and the Irish company Short Brothers (better known as Shorts) was hired to build the SB.5 to evaluate the innovative wing at three different sweep angles: 50, 60 and 69 degrees. Once the sweep of 60 degrees was shown to be stable in low-speed flight conditions, development of the Lightning prototypes continued.

Short SB.5, developed to test different wing sweep angles for the Lightning

While jet fighters or interceptors with two engines were nothing new, English Electric took the unique approach of stacking the engines one atop the other, rather than the more traditional method of placing them side by side. This arrangement kept the fuselage as narrow as possible to reduce drag. The first developmental aircraft, the P.1A, took its maiden flight on August 4, 1954, and even without afterburners (or “reheating,” as the British call it) the P.1A officially reached Mach 1 just a week after its first flight, though analysis of testing data showed that it had actually broken the sound barrier on its first flight. A misaligned Mach meter failed to indicate the correct speed. The next step in the development of the Lightning was the P.1B, which featured new Rolls-Royce Avon reheating turbojet engines. Now the Lightning showed its true speed potential, reaching speeds of Mach 2, and it became the world’s first aircraft capable of supercruise, supersonic flight without the use of afterburners. The P.1B entered production as the F.1 and received its official designation of Lighting in October 1958. The Lightning entered RAF service in 1960, and soon took on its designed role by intercepting high-flying Russian bombers such as the Tupolev Tu-16, Tu-22 and Tu-95 as they probed the edges of British airspace. With so much power available to Lightning pilots, the fighter could achieve an altitude of 36,000 feet in less than three minutes, and tests showed that the Lightning was capable of intercepting the high-flying Lockheed U-2 spy plane at 65,000 feet, though the results of those tests were a closely held secret. However, that speed came at a cost. The Lightning was a very thirsty aircraft, and the length of many of its missions was determined simply by the amount of fuel it could carry. The Lightning was armed with two 30mm ADEN cannons, along with hardpoints on the fuselage and both over and under the wings for mixtures of missiles, rockets or bombs. Cameras could also be housed in a ventral weapons bay. While the RAF was the primary operator of the Lightning, a number of the 337 aircraft produced were exported to Kuwait and Saudi Arabia. The RAF retired their Lightnings in 1988, but a small number of aircraft remain flying in the hands of private pilots. (Photo by Mike Freer via Wikimedia Commons)

April 4, 1917 – The first flight of the SPAD S.XIII. When WWI broke out on July 28, 1914, the airplane was still in its infancy. The Wright Brothers first flight had taken place a mere 11 years earlier, and military planners were only just beginning to discover a role for the airplane in combat. Initially, aircraft were used solely for reconnaissance, but the crews of scout planes soon started taking pistols and rifles into the air to take shots at enemy aircraft, and the concept of the dedicated fighter plane soon followed. Development proceeded apace and fighters were soon being produced by all the belligerents in the war, and one of the greatest of those was the SPAD XIII. The SPAD XIII (named for the Société Pour L’Aviation et sea Dérivés) was a development of the earlier, highly successful SPAD S.VII, but by 1917 the S.VII found itself outclassed by newer German designs. The primary need was for greater speed, and engine manufacturer Hispano-Suiza, who had upgraded the engine in the S.VII to gain more horsepower, was working on a yet more powerful, geared version of their 8A engine, an 8-cylinder, liquid cooled vee which would be used to power the S.XIII. The S.XIII was larger than its predecessor, and its armament was doubled by the fitting of two Vickers machine guns in place of the single machine gun of the earlier fighter. The S.XIII proved to be faster than its contemporaries such as the British Sopwith Camel and the German Fokker D.VII, and could outclimb them as well. Though the geared engines proved to be somewhat unreliable, the Allies considered it a price worth paying when when weighed against the S.XIII’s increased performance. Subsequent development of the engine, and improved construction methods, helped improve reliability. Following its first flight, the S.XIII was quickly introduced to frontline units the following month. Though deliveries were slow, the SPAD S.XIII eventually outfitted a total of 74 squadrons (Escadrilles), nearly every combat unit in action at the time.

American ace Eddie Rickenbacker with his SPAD X.III

Fifteen of the 16 American squadrons fighting in WWI flew the S.XIII, including the 94th Aero Squadron, better known as the Hat-in-the-Ring Squadron, where America’s leading ace Eddie Rickenbacker notched 26 confirmed victories, many coming at the controls of an S.XIII. The US and French were the primary users, but SPAD XIIIs also served with the Royal Flying Corps and the air forces of 16 other nations. Nearly 8,500 were produced, and an additional 10,000 more were slated for construction at the end of the war, but those orders were canceled following the Armistice. Despite the development of newer, more advanced fighters in the latter stages of the war, the S.XIII remained in service with the US until 192o, and with France until 1923. (US Air Force photos)

Short Takeoff

April 1, 2001 – The Hainan Island incident. While operating approximately 70 miles from the Chinese island province of Hainan, a US Navy Lockheed EP-3E ARIES II reconnaissance aircraft was intercepted by two Shenyang J-8 fighters. One of the fighters collided with the American plane, resulting in the death of the Chinese pilot. After regaining control of the heavily damaged aircraft, pilot Lt. Shane Osborne ordered the destruction of sensitive data and surveillance equipment before making an emergency landing on Hainan Island. The American crew of 21 men and 3 women was held and interrogated for 10 days before being released, and the EP-3E was dismantled and flown off the island on a chartered Russian Antonov An-124. For his actions in saving the ARIES and its crew, Lt. Osborne was awarded the Distinguished Flying Cross for “heroism and extraordinary achievement” in flight. (Lockheed photo)

April 3, 1982 – The first flight of the Airbus A310, a medium- to long-range wide-body airliner and the second airliner built by Airbus Industrie to enter production. The A310 was developed as a smaller derivative of the Airbus A300 (initially designated the A300B10) at a time when airlines were showing interest in smaller airliners for shorter routes with fewer passengers. Still, the A310 has a greater range than its larger predecessor, and has become popular on many transatlantic routes. The A310 has also been developed into a convertible freight version and an aerial tanker for the military. Produced between 1983-1998, a total of 255 have been built. (Photo by Laerent Errera via Wikimedia Commons)

April 3, 1933 – The US Navy airship USS Akron (ZRS-4) crashes into the Atlantic Ocean. Commissioned in October of 1931, the Akron was the world’s first purpose-built flying aircraft carrier and one of the largest airships ever built. After encountering severe weather off the coast of New Jersey, the Akron crashed into the sea, killing 73 of her 76 crew members, including Rear Admiral William A. Moffett, a leading proponent for the military applications of airships. The disaster caused the largest loss of life in any airship crash, and signaled the beginning of the end of the use of airships by the Navy. (US Navy photo)

April 3, 1933 – The first flight over Mt. Everest. Twenty years before the first successful ascent, Flight Lieutenant D.F. McIntyre and Douglas Douglas-Hamilton (Lord Clydesdale), along with two observers, piloted a Westland PV-6 and a Westland Wallace over the summit of the tallest mountain in the world. The aircraft had been modified with a supercharged Bristol Pegasus engine, an enclosed rear cockpit, cockpit heating, and oxygen for the crew. The mission was called the Houston-Mount Everest Flight Expedition in honor of its patron, Lady Houston, and the aircraft cleared the top of the 29,029-foot summit with just 100 feet to spare. The observers provided the first aerial survey of Everest and the surrounding area, and the flight emphasized the need for the development of pressurized aircraft. (National Geographic photo)

April 3, 1926 – The birth of Virgil Ivan “Gus” Grissom. Born in Mitchell, Indiana, Grissom was a test pilot, mechanical engineer, US Air Force combat pilot in Korea and one of the original seven Project Mercury astronauts. As part of the Mercury program, Grissom was the second American to fly in space after John Glenn, and the first US astronaut to go to space twice when he flew aboard Gemini 3. Grissom was chosen as the Command Pilot for Apollo 1, but he and astronauts Ed White and Roger Chaffee were killed on January 27, 1967 when a fire broke out in the Command Module during a ground test. All three astronauts were posthumously awarded the Congressional Space Medal of Honor. (NASA photo)

April 4, 1983 – The launch of Space Shuttle Challenger on STS-6, the sixth launch of the Space Shuttle program and the maiden flight of the Challenger. During the 5-day flight, astronauts deployed the first tracking and data relay satellite (TDRS-1), and conducted the first spacewalk from a Shuttle, employing the new Extravehicular Mobility Unit (EMU) spacesuit for the first time. STS-6 was the last Shuttle flight with a four-astronaut crew which consisted of Paul Weitz, Karol Bobko, Story Musgrave and Donald Peterson. Challenger returned to Edwards Air Force Base on April 9, ending the first of its 9 successful flights before the orbiter was destroyed in an explosion shortly after launch on January 28, 1986 with the loss of 7 astronauts. (NASA photo)

April 4, 1993 – The first flight of the Fokker 70, a medium-range airliner derived from the larger Fokker 100, both of which were developments of Fokker’s first airliner, the Fokker F28 Fellowship. The Fokker 70 was designed to fit a capacity gap between the smaller Fokker 50 or ATR 42 turboprop airliners and the larger Boeing 737 or McDonnell Douglas MD-80. The Fokker 70 is powered by a pair Rolls-Royce Tay 620 turbofans and can accommodate up to 85 passengers in a single-class configuration at ranges of up to 2,119 miles. A total of 47 aircraft were built before production ended in 1997, and they mainly serve shorter routes in Europe. (Photo by Björn Strey via Wikimedia Commons)

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