Welcome to This Date in Aviation History, getting you caught up on milestones and important historical events in aviation from September 19 through September 22.


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September 21, 1964 – The first flight of the North American XB-70 Valkyrie. Following WWII, and the dawning of the Nuclear Age, Cold War combatants were looking for ways to deliver nuclear weapons deep into the heart of their rival’s territory. But by 1959, when the first ICBM installation became operational in Russia, the emphasis shifted from the nuclear bomber to the nuclear-tipped missile, and for that reason, the giant XB-70 Valkyrie became somewhat of an anachronism, a bomber for an earlier age. Beginning in 1955, the US Air Force issued a requirement for a new bomber that would have the payload capacity of the Boeing B-52 Stratofortress but the supersonic speed of the Convair B-58 Hustler. While some early designs were considered, rapid development of supersonic science pointed to a large delta wing being the most efficient for such a bomber. While initial plans were for a bomber that would fly to the target, drop the bomb from lower altitude and “scoot” away from the blast, designers discovered that from the standpoint of fuel use versus miles traveled, it was more efficient for the aircraft to spend its entire mission at top speed, in this case, Mach 3. North American engineers also found a way to make use of a phenomenon known as compression lift, where the shock wave made by the plane could help create lift. They added drooping wingtips to take full advantage of this effect, with the added benefit of decreasing drag. While the XB-70 would be unreachable by any fighters, advances in air-to-air missiles suddenly put the whole project in doubt. Air Force doctrine changed from high altitude supersonic bombing to low altitude penetration. Thus, the Valkyrie would have to be flown at low levels, where it was barely faster than the B-52, and with a smaller payload. Ultimately, the XB-70 became a Cold War Era political football, the stuff of campaign promises and political bargaining, and the project was canceled. With no real bombing mission for the plane to perform, the XB-70 became a research testbed for supersonic flight. Of the two that were built, Valkyrie No. 2 was lost in a mid-air collision during a formation flight photo shoot that caused the death of two pilots and the serious injury of a third. Aircraft No. 1 continued to serve its research role, with its final supersonic flight taking place in February 1969 when it was flown to the US Air Force Museum in Dayton, Ohio. (US Air Force photo)


September 21, 1961 – The first flight of the Boeing CH-47 Chinook. When the US Army placed an order for the Sikorsky R-4 in 1943, it was the beginning of a relationship with rotor wing aircraft that would eventually give rise to the concepts of vertical envelopment that were honed in the Vietnam War. But it soon became clear that while the helicopter was good at moving soldiers, the Army needed something bigger to lift artillery and heavy equipment. For a time, that job was done by the Sikorsky CH-37 Mojave, but work began in 1957 to procure a modern, turbine-powered helicopter as a replacement for the Mojave that would provide even more lifting power and speed. A tandem helicopter, with two rotors providing lift for the heavy loads, was deemed the best design to pursue. The first helicopter to come out of this requirement was the YHC-1A, but it was deemed too small and was eventually adopted by the US Marine Corps as the CH-46 Sea Knight in 1962. Its smaller size would be an advantage for the carrier-based Marines. The Army requested a larger helicopter, and the result was the YCH-1B, which would become the CH-47 Chinook, following the tradition of naming Army helicopters after Native American tribes. The new helicopter was powered by two Lycoming T55-GA-714A turboshaft engines each producing 4,733 hp and turning counter-rotating propellers that would eliminate the need for an anti-torque rotor. The two engines would give the Chinook a top speed of 170 knots, faster than the utility and attack helicopters of the day. They also provided enough power to carry up to 55 troops or 28,000 pounds of cargo. Continuously upgraded since its introduction, the Chinook now has newer Honeywell engines, composite rotor blades, redundant electrical systems and advanced avionics. Not only was the Chinook popular with the US Army, but it was exported to 23 nations and remains in production, with over 1200 aircraft built. Along with its heavy lifting counterpart the Lockheed C-130 Hercules, it is one of the few aircraft that has seen a production and service life of over 50 years. (US Army photo)


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September 21, 1942 – The first flight of the Boeing B-29 Superfortress. Strategic bombing came into its own in WWII, and the conflict saw the production of ever more powerful aircraft with greater range, payload and firepower. By the time the Superfortress entered service in 1944, it was the most technologically advanced bomber of its era, and even though it was late in the war, it had a profound effect on the late stages of the Pacific campaign. But even though the B-29 didn’t start dropping bombs until late in the war, Boeing’s work on a pressurized bomber began all the way back in 1938 as an independent project. Then, in 1939, at the urging of Charles Lindbergh, the Army began to pursue a so-called “superbomber,” one that would be capable of carrying 20,000 lbs of bombs 2,667 miles at a speed of 400 mph. Boeing’s previous work would form the basis for their entry into the competition to produce the new bomber. The competition was between Boeing, Consolidated, Lockheed and Douglas, and Boeing would receive an order for two prototypes in August 1940. By May of 1941, that order was increased to 250 production bombers, and then to 500 bombers in January 1942. The Consolidated B-32 Dominator, a more traditional design that was not selected in the initial competition, would still be produced in small numbers should the production of the B-29 run into difficulties. And as good as the B-29 would become, serious problems with the Wright R-3350 Duplex-Cyclone radial engines would plague the early development of the new bomber. Those problems would eventually be ironed out, but it wasn’t until the introduction of Pratt & Whitney R-4360 “Wasp Major” engines after the war that the engine problems were entirely solved. The B-29 would go on to have a stellar career as a long range bomber, perfect for the island hopping campaign over the vast reaches of the Pacific Ocean, and would become the only WWII design to go on to a lengthy career after the war and into the Korean War. As the KB-29, it served as the basis for one of the first aerial refueling tankers, it would be upgraded as the B-50 and serve until 1965, and it would form the basis for the Boeing C-97 Stratofreighter, the Boeing 377 Stratocruiser passenger airliner and the Pregnant/Super Guppy series of large cargo aircraft. Nearly 4,000 were produced, but only one remains flying, though it is hoped that a second restored aircraft will soon join its ranks. (US Air Force photo)


Short Take Off


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September 19, 1969 – The first flight of the Mil Mi-24 helicopter gunship. A large gunship that is also capable of carrying eight passengers or troops, the Mi-24 (NATO reporting name Hind) is essentially a flying infantry fighting vehicle. It entered service with the Soviet Union in 1972, and an estimated 2,300 have been produced for the Russian Air Force and more than 30 export countries. (Photo by Chris Lofting via Wikimedia Commons)


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September 19, 1962 – The first flight of the Aero Spacelines Pregnant Guppy. The Pregnant Guppy was developed from the Boeing 377 Stratocruiser as an oversized cargo aircraft to deliver the first and second stages of NASA’s Titan II rockets to Cape Canaveral as part of Project Gemini. Only one Pregnant Guppy was built, but it was followed by the larger and more capable Super Guppy. (NASA photo)


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September 19, 1949 – The first flight of the Fairey Gannet. The Gannet was an anti-submarine warfare (ASW) aircraft developed for England’s Fleet Air Arm that was powered by an Armstrong Siddeley Double Mamba turboprop turning a contra-rotating propeller. It served in both the ASW and electronic countermeasures (ECM) roles until 1978. (Photo by Mike Freer via Wikimedia Commons)


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September 20, 1951 – The first flight of the Grumman F9F (F-9) Cougar. The Cougar was such a significant upgrade to its predecessor, the Grumman F9F Panther, that the Navy gave it a new name, even though it was basically a Panther with a swept wing and much more powerful engines. Coming too late to see service in Korea, The Cougar was replaced by the Grumman F11F Tiger and Vought F8U Crusader before the outbreak of the Vietnam War. Nearly 1,400 were built, and many ended their life as a target drone. (US Navy photo)


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September 20, 1943 – The first flight of the Consolidated PB4Y Privateer, a maritime patrol bomber that was derived from the Consolidated B-24 Liberator. The Privateer was longer than the Liberator, and featured a single vertical stabilizer. Armament was also increased, but engine turbochargers were removed since it operated at lower altitudes. 739 Privateers were built, and they saw service in both WWII and the Korean War. (US Navy photo)


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September 20, 1943 – The first flight of the de Havilland Vampire, the second jet fighter to enter service with the RAF following the Gloster Meteor, and the first to use a single engine. It is notable for the twin tail design, with the engine housed in a central, egg-shaped fuselage. This arrangement made the tailpipe shorter to make full use of the limited power available in earlier jet engines. The Vampire was phased out by the RAF by the end of the 1950s. (Photo by Peter Bakema via Wikimedia Commons)


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September 21, 2012 – Endeavour, the last Space Shuttle to be airborne, completes a three-day journey atop the Shuttle Carrier Aircraft (SCA) as it is transported from Cape Canaveral, Florida to Los Angeles, California. During the flight, the SCA made low passes over Florida’s Space Coast and NASA centers in Mississippi and Louisiana before landing in Houston to refuel. Next they flew over the White Sands Test Facility in New Mexico, over Tucson, Arizona as a tribute to Congresswoman Gabrielle Giffords, then on to Edwards Air Force Base in California. On its final day, the SCA and Endeavour made low level passes over Sacramento, San Francisco, Silicon Valley, and Los Angeles, before landing at Los Angeles International Airport. (NASA Photo)


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September 21, 1945 – The first flight of the Hakwer Sea Fury. The Sea Fury was the last propeller-driven fighter to enter service with the Royal Navy, as well as one of the fastest single engined aircraft ever built. Introduced in 1947, the Sea Fury was too late for WWII, but saw action over Korea and was flown by Cuba during the Bay of Pigs Invasion of 1961. (Photo by Dave Miller via Wikimedia Commons)


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September 22, 1974 – The introduction of the Grumman F-14 Tomcat. Developed after the failure of the General Dynamics F-111B carrier-based interceptor, the F-14 became the US Navy’s primary air superiority fighter and fleet defense aircraft. Although a new design, it kept the engines, weapons system and swing wing of its unsuccessful predecessor. Over 700 were produced, with a number being sent to Iran during the rule of the Shah. The F-14 was officially retired on the same date in 2006 after 32 years of service. (US Navy Photo)


If you enjoy these Aviation History posts, please let me know in the comments. And if you missed any of the past articles, you can find them all at Planelopnik History.

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