Welcome to This Date in Aviation History, getting you caught up on milestones, important historical events and people in aviation from May 6 through May 9.

May 6, 1941 – The first flight of the Republic P-47 Thunderbolt. From its inception in WWI up until the middle of WWII, the single-engine fighter generally was, by design, a relatively small aircraft. Most designers and fighter pilots believed that a smaller, lighter aircraft would more agile and more maneuverable in the air. Fighters such as the Mitsubishi A6M Zero, Supermarine Spitfire, and North American P-51 Mustang are perhaps the finest examples of this way of thinking. So, when the enormous P-47 Thunderbolt arrived on the scene, weighing in at 10,000 pounds (about 2,500 pounds more than a P-51, and fully twice the weight of a Spitfire), pilots were skeptical. But that skepticism was proven wrong, and the Thunderbolt secured a place in the pantheon of the greatest fighters of the war. But the P-47 didn’t start out as a huge aircraft. The Thunderbolt traces its roots back to 1939, when Republic Aviation proposed the development of a lightweight fighter, similar in size and capability to the Curtiss XP-46, which had been rejected by the US Army Air Corps. The Army wasn’t interested in Republic’s proposal either, so designer Alexander Kartveli continued work on the design, and the aircraft gradually got bigger and bigger as more guns were added to it. The proposal now called for two .50 caliber machine guns in the nose and eight .50 caliber guns in the wings, and the fighter was to have been powered by an Allison V-12 engine turning a 10-foot diameter propeller. But as development progressed, reports from the front lines in Europe indicated that even this aircraft would not be adequate for the Army’s needs. Kartveli now proposed a massive fighter that would be powered by a supercharged 18-cylinder Pratt & Whitney R-2800 Double Wasp radial engine, the same engine that was used in the Vought F4U Corsair and that would also power the forthcoming Grumman F6F Hellcat. In a nod to the importance of the supercharger for high-altitude performance, the layout of the engine and supercharger were actually developed first, and the airplane was essentially built around it. The pilot sat on top of the main air intake duct, and the carburetor ducts were routed around the cockpit. The massive supercharger was placed in the tail of the aircraft, where it actually proved to be quite a successful arrangement, and rarely suffered any battle damage.

To pull the massive fighter through the air, the 10-foot diameter propeller of the P-47's predecessor gave way to a massive 12-foot diameter Curtiss Electric constant speed propeller. But the huge prop created design difficulties of its own, as the landing gear needed to be long enough to keep the prop from striking the ground. Kartveli’s team solved that by creating a telescoping strut that extended by 9 inches after it was lowered. Early models of the P-47 used a razorback canopy configuration, but pilots complained about poor visibility. To correct that shortcoming, the British fitted a P-47 with a plexiglass bubble canopy taken from a Hawker Typhoon, and soon all Thunderbolts were built with such a canopy, and that became the definitive model through the rest of the war. Nearly two years of testing followed the Thunderbolt’s first fight, and the P-47 flew its first combat missions in April of 1943. Pilots who were dubious of the huge fighter at first soon discovered that the Thunderbolt, or Jug as it came to be known, could out dive anything in the sky, and its rugged construction became legendary for bringing pilots home after suffering massive battle damage. Although initially supplanted by the P-51 in the bomber escort mission, the P-47 eventually regained that role as continued development increased its range, and many Thunderbolts escorted bombers to the target and then dropped down near the ground on the return flight to destroy targets of opportunity along their path using machine guns, bombs or rockets. With the end of the war, the Army order for 6,000 more P-47s was canceled, but by that time more than 15,600 had already been built, just beating out the Mustang as the most-produced American fighter in history. (Photo by Airwolfhound via Wikimedia Commons; illustration author unknown)

May 6, 1937 – The crash of the Zeppelin Hindenburg. Before transatlantic passenger aircraft became common around 1940, flying passengers across the Atlantic Ocean was the the bailiwick of the rigid airship. These “ocean liners of the sky” grew ever larger, with increasing ranges, culminating in the Hindenburg and Graf Zeppelin II, the largest aircraft ever to take to the skies. The Hindenburg, German dirigible LZ-129 (Luftschiff Zeppelin #129, registration D-LZ129) was a rigid airship and the lead ship of the Hindenburg class. Designed and built by the Zeppelin Company (Luftschiffbau Zeppelin GmbH), Hindenburg was named after the late Field Marshal Paul von Hindenburg, the President of Germany from 1925-1934, and was constructed of a duralumin frame fitted with 16 cotton gas bags. The outer skin of the dirigible was made of cotton fabric that was covered with a reflective coating meant to protect the gas bags from ultraviolet and infrared radiation. Power for the Hindenburg was provided by four 16-cylinder Daimler-Benz DB 602 diesel engines which produced 1,200 hp each, and gave the airship a top speed of 85 mph. Hindenburg took its maiden flight on March 4, 1936, and was soon plying the route from Germany to America, with its first crossing of the Atlantic completed on May 6, 1936. That crossing set a record for the time, completing the voyage 64 hours, 40 minutes. Eastward transatlantic flights, with help from prevailing winds, averaged around 55 hours. Hindenburg was originally built to be filled with helium, but helium was rare and came at an exorbitant cost. Construction of the Hindenburg went ahead regardless, even though the designers knew they would have trouble obtaining helium from the United States, where it was a byproduct of natural gas mining. When the US refused to lift the export ban on helium, Hindenburg’s designers made the fateful decision to switch to highly flammable hydrogen instead, even though the dangers of hydrogen were well known.

Hindenburg on its maiden flight, March 4, 1936

On May 3, 1937, Hindenburg departed Frankfurt for a transatlantic crossing to Lakehurst, New Jersey. Slowed by strong headwinds, she arrived over New Jersey on May 7, but the landing was delayed by a line of thunderstorms. Hindenburg was finally cleared to land at about 7:00 pm. At 7:21 pm, shortly after dropping mooring lines to the ground crew, Hindenburg suddenly burst into flames and crashed next to the mooring mast. Within thirty seconds, Hindenburg was reduced to a smoldering wreck of twisted, charred metal. Thirty-five passengers and crew died in the crash and flames, and one man on the ground was killed. The cause of the crash has been the topic of much debate and remains somewhat of a mystery to this day. Some suspect sabotage, while others suggest atmospheric conditions could have played a role in the explosion and fire. One of the more plausible theories is that hydrogen gas leaking from one of the cells was ignited by static electricity. During Hindenburg’s landing, witnesses reported seeing large amounts of water ballast being dumped, which could indicate a significant leak of hydrogen that caused the airship to descend more rapidly than normal. After the crash, the duralumin hulk was returned to Germany where it was recycled for use in the construction of Luftwaffe aircraft. The crash marked the effective end of transatlantic Zeppelin transport, despite a long list of passengers who were still willing to cross the ocean in an airship. With WWII under way in Europe, Graf Zeppelin II was scrapped in 1940 while still under construction, and its duralumin also went to support the German war effort. (US Navy photo; Hindenburg photo author unknown)

Short Takeoff

May 6, 2006 – The US Air Force retires the Hanoi Taxi, the last Lockheed C-141 Starlifter. The Starlifter was a strategic airlifter that entered service with the Air Force in 1965 and saw extensive service during the Vietnam War. Starlifter serial number 66-0177, known as the Hanoi Taxi, became famous as the aircraft that repatriated the first prisoners of war released from Vietnam as part of Operation Homecoming in 1973. After the war, the Hanoi Taxi continued its regular airlift duties, and aided in the evacuation of victims of Hurricane Katrina in 2005. With the scheduled retirement of the final eight Starlifters, veterans and former POWs were given the opportunity to fly in the Hanoi Taxi once more and, on its arrival at Wright-Patterson AFB, the aircraft was enshrined into the National Museum of the United States Air Force. (US Air Force photo)

May 6, 1942 – The first flight of the Kawanishi N1K Kyōfū, originally developed as a floatplane fighter for the Imperial Japanese Navy during WWII. When the floatplane version turned out to be ineffective, the N1K was developed into the N1K-J (Shiden), a land-based fighter known to the Allies as the George, and proved to be one of the most effective fighters of the war. It was heavily armed and highly maneuverable, and was equipped with a mercury switch that automatically extended the flaps, helping to decrease the turning radius during a dogfight. In battle, the Shiden proved a match for the best Allied fighters, but came too late in the war, and in insufficient numbers, to make a significant contribution to the Japanese war effort. (US Air Force photo)

May 6, 1935 – The first flight of the Curtiss P-36 Hawk. A contemporary of the Hawker Hurricane and Messerschmitt Bf 109, the P-36, also known as the Hawk Model 75, was an early example of the new generation of all-metal cantilever monoplane fighters. Introduced in 1938, the Hawk saw little service in WWII with the US Army Air Corps, but found great success as an export fighter, where it was flown with good effect by the French during the Battle of France. It is perhaps best known as the predecessor to its much more famous descendant, the P-40 Warhawk. Only 215 Hawks were built for the US Army Air Corps, but 900 were exported to international customers. The last Hawks were retired by the Argentine Air Force in 1954. (US Air Force photo)

May 6, 1930 – The first flight of the Boeing Monomail. The Monomail, so named because of it monoplane design and its intended purpose as a mail plane, was an important development not only for its design but also for its all-metal construction, which also featured a streamlined fuselage and included fully-retractable landing gear. Eventually stretched to carry six passengers, the Monomail suffered from an underpowered engine and the lack of a variable-pitch propeller, and was soon surpassed by more modern designs. However, many of the technological advances made with the Monomail found their way into later Boeing designs, notably the YB-9 bomber and the P-26 Peashooter.(Photo author unknown)

May 7, 1992 – The first flight of the Space Shuttle Endeavour, the sixth and final Space Shuttle built and the fifth flown into space by NASA (Enterprise, the first shuttle, was used for static testing and glide tests). Construction of Endeavour began in 1987 as a replacement to the Space Shuttle Challenger which was lost, along with its crew, in 1986. Endeavour was named for British explorer Capt. James Cook’s HMS Endeavour (hence the British spelling), and it accomplished a number of firsts, including carrying the first African American woman astronaut to space, Mae Jemison, and completing the first mission to repair the Hubble Space Telescope. Following its first flight in 1992 on STS-49, Endeavour served until 2011, flying a total of 25 missions before its retirement following STS-134, when it was moved to the California Science Center in Los Angeles where it is on display. (NASA photo)

May 7, 1946 – The first flight of the Handley Page Hastings, a British troop transport and general cargo plane that served the Royal Air Force as a replacement for the Avro York. The Hastings was powered by four Bristol Hercules radial engines and was capable of carrying up to 50 troops, 35 paratroops, 32 stretchers or 20,000 pounds of cargo. The Hastings first saw service as part of the Berlin Airlift in 1948, where it was used primarily to deliver coal to the blockaded city. The Hastings also served during the Suez Crisis in 1956, and was finally retired in 1977 and replaced in RAF service by the Lockheed C-130 Hercules. A total of 151 Hastings were produced from 1947-1952. (Photo by Mike Freer via Wikimedia Commons)

May 9, 1967 – The first flight of the Fokker F28 Fellowship, a short range jet airliner developed by the Dutch aircraft manufacturer Fokker. Initially designed to accommodate 50 passengers, production aircraft eventually carried 65 passengers, and future variants were expanded to carry as many as 79 passengers. Similar in appearance to the Douglas DC-9, the Fellowship was powered by a pair of Rolls-Royce Spey low-bypass turbofans that gave the F28 a cruising speed of about 520 mph and a range of up to 1,200 miles, depending on the variant. A total of 241 aircraft were produced from 1967-1987, and the type remains in limited service. (Photo by Rolf Wallner via Wikimedia Commons)

May 7, 1944 – The first flight of the Beechcraft XA-38 Grizzly, a twin-engine ground attack aircraft developed by Beechcraft for the proposed invasion of Japan. The US Army Air Forces was looking for a replacement for the Douglas A-20 Havoc that would be capable of destroying bunkers or other hardened targets. The Grizzly was fitted with a 75mm cannon in the nose, along with two forward-firing .50 caliber machine guns. Though the Grizzly showed promise, the Boeing B-29 Superfortress took priority in the allocation of Wright R-3350 Duplex Cyclone engines, and the Grizzly never entered production. Only two were built, with one scrapped and the whereabouts of the other unknown. (US Air Force photo)

May 8, 2004 – The death of William J. “Pete” Knight. Knight was born in Noblesville, Indiana on November 18, 1929, and joined the US Air Force in 1951. He served as a test pilot at Edwards Air Force Base flying the F-100 Super Sabre, F-101 Voodoo, F-104 Starfighter, T-38 Talon and F-5 Freedom Fighter. Following the cancelation of the Boeing X-20 Dyna-Soar project, Knight was selected to fly the hypersonic North American X-15. On October 3, 1967, Knight piloted the X-15 to a speed of Mach 6.72 (4,520 mph), setting an absolute speed record for flight that still stands. He was also one of 5 pilots to earn astronaut wings when he reached an altitude of 280,550 feet. After his stint as a test pilot, Knight flew 253 combat missions during the Vietnam War, and retired from the Air Force in 1982. Knight also served as a California state politician. (NASA photo)

May 9, 1981 – HMS Hermes enters service as the first aircraft carrier to employ a “ski jump” deck. Hermes was laid down on June 21, 1944 as the last of the Centaur class of aircraft carriers, though it was not finished until 1957. After service as a standard aircraft carrier, Hermes was converted into a “Commando Carrier,” with catapults and arresting gear removed. At the time, a 12-degree ski jump was added to aid in the launch of the STOVL British Aerospace Sea Harrier. Hermes served as the British flagship during the Falklands War in 1982, where her fighters and helicopters supported the British forces in British efforts to recapture the islands. After decommissioning in 1984, Hermes was sold to India, where she became the INS Viraat and served until 2016. (Photo author unknown)

May 9, 1949 – The first flight of the Republic XF-91 Thunderceptor. Sticking with the “thunder” in their aircraft names, Republic Aviation designed the Thunderceptor as a mixed propulsion interceptor that was powered by a jet engine for most of its flight, but could use rocket power for added speed and climb during interception. The Thunderceptor was notable for its use of an inverse tapered wing that was intended to help with the problem of pitch-up during transonic flight. With the rapid advances in jet engine technology, the Thunderceptor was never adopted. Only two were built, though it does own the distinction of being the first US fighter to exceed Mach 1 in level flight. (US Air Force photo)

May 9, 1962 – The first flight of the Sikorsky CH-54 Tarhe (S-64 Skycrane), a heavy-lift helicopter that traces its lineage back to the Sikorsky S-56 (military CH-37 Mojave), an early heavy lifter which was then developed into the Sikorsky S-60 which served as the basis for the CH-54. The Tarhe could lift up to 20,000 pounds, either in a detachable pod or slung beneath the fuselage, and the crew of three allowed one pilot to sit in a rear-facing seat to control the helicopter during loading operations. Just over 100 Tarhes were built and they saw extensive service in Vietnam. Though the military retired the type in 1991, many are still used by private firms for heavy-lift operations and firefighting. (US Army photo)

May 9, 1926 – Richard Byrd and Floyd Bennett make the first flight over the North Pole. While some historians credit Byrd and Bennett with this milestone in aviation exploration, there remains significant controversy surrounding their accomplishment. With Bennett as pilot, Byrd planned to take off from Spitsbergen (Svalbard) in their Fokker F.VIIa-3m, fly over the Pole, and return. However, evidence of erasures in Byrd’s personal diary cast doubt on whether the team actually reached the Pole before returning to Spitsbergen. Nevertheless, Byrd and Bennett were hailed as national heroes and awarded the Congressional Medal of Honor. Three days later, a flight by the airship Norge, lead by Roald Amundsen, flew from Spitsbergen to Alaska, leaving no doubt that they crossed the Pole. The debate continues as to which explorer was actually first. (Photo author unknown)

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