Welcome to This Date in Aviation History, getting of you caught up on milestones, important historical events and people in aviation from September 19 through September 21.


(US Air Force)

September 21, 1964 – The first flight of the North American XB-70 Valkyrie. During the Second World War, strategic bombing evolved into an extremely destructive endeavor, and reached an earth-shattering crescendo with the nuclear attacks on Hiroshima and Nagasaki that finally brought an end to the most destructive war in human history. The Nuclear Age had dawned, but the intercontinental ballistic missiles (ICBM) that we know and fear today were yet to be developed. Attacking an enemy with nuclear weapons was still a mission for long-range bombers and, like their predecessors, early postwar bombers remained susceptible to fighters and interceptors. But with the arrival of supersonic bombers, it was hoped that these planes could fly at altitudes and speeds beyond the reach of contemporary interceptors, and such was the genesis of the radical North American XB-70 Valkyrie. However, by the time the Valkyrie finally took to the air, the ICBM had taken over the role of nuclear attack, and the Valkyrie became an anachronism, a bomber for an earlier age.

North American XB-70 Number 1 in flight. Note the lowered wingtips to take advantage of the compression left. (US Air Force)

In 1955, the US Air Force issued a requirement for a new strategic bomber that would have the payload capacity of the Boeing B-52 Stratofortress but the supersonic speed of the Convair B-58 Hustler. Various radical designs were considered, but the rapid development of supersonic science indicated that a large delta wing, with forward canards for added stability and control, would be the most efficient shape for such a bomber. Initially, the Air Force planned for a bomber that would fly to the target, drop the bomb from lower altitude, and then “scoot” away from the blast at supersonic speed. But engineers discovered that, from the standpoint of fuel use versus miles traveled, it was actually more efficient for the bomber to spend its entire mission at top speed.

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The “six pack,” six afterburning GE turbojets at the back of the Valkyrie. (Author unknown)

In the case of the XB-70, that top speed would be Mach 3 at 70,000 feet, propelled by six General Electric YJ93 afterburning turbojets, all mounted side by side in what was known as the “six pack.” That sort of performance generated a lot of heat, so fuel was pumped through heat exchangers before flowing to the engines in order to keep the aircraft cool. North American engineers also discovered a way to make use of a phenomenon known as compression lift, where the shock wave made by the plane helped create lift. Drooping wingtips allowed the Valkyrie to take full advantage of this effect, with the added benefit of decreasing drag.

XB-70 Number 2 flies with four other aircraft powered by General Electric engines. Shortly after this top photo was taken, the pilot of the Lockheed F-104 Starfighter (second from right with red tail) lost control and flipped over the top of the Valkyrie, breaking off the vertical stabilizer and rendering the giant bomber uncontrollable. The F-104 pilot and one XB-70 pilot were killed. (US Air Force)

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Though the XB-70 would be unreachable by any contemporary fighters, advances in air-to-air missiles suddenly put the whole project in doubt, causing the Air Force to switch its doctrine 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, while carrying 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 in 1961. With no real bombing mission for the plane to perform, the two XB-70s that were completed became testbeds for supersonic research. On June 8, 1966, Valkyrie No. 2 was lost in a mid-air collision during a formation flight photo shoot for engine manufacturer GE that caused the death of two pilots and the serious injury of a third. Aircraft No. 1 continued to serve in its research role, and made its final supersonic flight in February 1969 when it was flown to the National Museum of the United States Air Force in Dayton, Ohio. 


(US Army)

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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 marked the beginning of a relationship with rotor wing aircraft that would eventually give rise to the practice of vertical envelopment that became a primary means of attack during the Vietnam War. But the Army soon realized that, while the helicopter was good at moving soldiers, they needed something bigger to lift artillery, heavy equipment, and greater numbers of soldiers. For a time, that role was filled 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 could provide more lifting power and higher speeds than the CH-37's pair of radial engines could provide.

The HC-1B during a test flight. (US Army)

The Army was of two minds on the project. One group imagined the new helicopter as being able to carry a full squad of 15 soldiers, while the other group wanted a much larger helicopter capable of moving artillery pieces and other battlefield supplies. The second group carried the day, and Vertol began working on a tandem helicopter, with two rotors providing extra lift for heavy loads. (Vertol was originally Piasecki Helicopter, an early advocate of tandem helicopter design, and was acquired by Boeing in 1960.) The first helicopter to come out of the Army requirement was the YHC-1A, but the Army deemed that it was too small, though it was eventually adopted by the US Marine Corps as the Boeing Vertol CH-46 Sea Knight in 1962, where its smaller size would be an advantage for the carrier-based Marines. So Boeing Vertol enlarged the YCH-1A into the YCH-1B, which finally became the CH-47 Chinook following the Army tradition of naming helicopters after Native American tribes. The new helicopter was powered by a pair of Lycoming T55 turboshaft engines each producing 4,733 hp and turning counter-rotating propellers. The two engines gave the Chinook a top speed of 170 knots, faster than the utility and attack helicopters of its day. They also supplied enough power to carry up to 55 troops or 28,000 pounds of cargo.

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A Chinook brings supplies to a hilltop in Vietnam in 1967. (US Army)

The Chinook entered service with the Army in Vietnam in 1965, where its size quickly became invaluable in the supply of forward bases. Its lifting power also made it possible to haul artillery pieces to remote mountaintop fire bases that were unreachable by roads. Not only was the Chinook popular with the US Army, but it was exported to 23 nations and remains in production, with over 1,200 aircraft built, making it the most-produced tandem helicopter in history. Continuously upgraded since its introduction, the Chinook now has newer, more powerful Lycoming engines (now produced by Honeywell), composite rotor blades, redundant electrical systems and advanced avionics. Along with its fixed-wing heavy lifting counterpart, the Lockheed C-130 Hercules, the CH-47 is one of the few aircraft that has seen a production and service life of over 50 years.

The Chinook has proven particularly useful in Afghanistan, where its powerful engines allow it to operate at higher altitudes and in hotter temperatures than other Army helicopters. Here, Chinooks arrive to pick up US Army soldiers following a mission. (US Army)

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(US Air Force)

September 21, 1942 – The first flight of the Boeing B-29 Superfortress. In the years leading up to WWII, there were two main schools of thought about how best to use bombers. One was strategic bombing, which sought to defeat the enemy by destroying their means of production of war materiel while also destroying the morale of the civilian population. The other was tactical bombing, in which bombers worked more closely with ground troops to carry out specific battlefield tactics and destroy targets of immediate military value. While Germany, with their Blitzkrieg warfare, became almost wholly invested in the theories of tactical bombing, America and her allies followed the doctrines of strategic bombing, particularly the theories espoused by Italian general Giulio Douhet and American general Billy Mitchell. To that end, the Americans produced ever larger bombers, capable of carrying heavy loads of bombs at great distances.

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Pre-production YB-29 Superfortresses. Production aircraft were delivered unpainted. (US Air Force)

When the Superfortress entered service in 1944, it was the most technologically advanced bomber of its era, and even though it arrived late in the war, it had a profound effect on the later stages of the Pacific campaign. 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 over 2,600 miles at a speed of 400 mph. Boeing’s previous work formed the basis for their entry into the competition between Boeing, Consolidated, Lockheed and Douglas to produce the new bomber, and Boeing received an order for two prototypes in August 1940. By May of 1941, the order was increased to 250 production bombers, and then to 500 in January 1942. The Consolidated B-32 Dominator, a more traditional design that was not selected in the initial competition, was ordered into production in small numbers should the production of the B-29 run into difficulties.

B-29s of the 468th Bombardment Group attack Rangoon Burma in 1945. (US Air Force)

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At the time the B-29 was being developed, the piston-powered aircraft was reaching the zenith of technological advancement, and the Superfortress was at the forefront. In addition to its streamlined shape and the adoption of pressurization, the B-29 was armed with up to ten Browning M2 .50 caliber machine guns in remotely operated, motorized turrets. With onboard targeting computers and a system that could link the guns together, one gunner could control two or more sets of guns to focus the greatest amount of firepower against enemy fighters. And that was only if the fighters could reach the high-flying bomber. Operating at nearly 32,000 feet and at speeds of up to 350 mph, the B-29 was almost unreachable by most Japanese fighters. But as good as design of the B-29 was, serious problems with the complex Wright R-3350 Duplex-Cyclone radial engines plagued the early development of the new bomber. Those problems were eventually ironed out, but it wasn’t until the introduction of Pratt & Whitney R-4360 Wasp Major engine after the war that the problems were entirely solved.

B-29s operating from Tinian in the Mariana Islands in 1945. Japanese-held islands were captured and quickly turned into forward air bases. (US Air Force)

The Army Air Forces originally intended the B-29 to be used against Germany, but delays in production meant that it was flown exclusively against Japan in the Pacific Theater. The B-29's extreme range proved a vital asset as it attacked Japanese forces and island of Japan from bases in China before relocating to bases built on Pacific islands captured captured during the Allies’ island hopping campaign. When conventional bombs proved to less effective against the scattered Japanese military infrastructure, B-29s were flown in devastating firebombing raids against Japanese cities. And specially modified Silverplate B-29s were used in the atomic bombings of Hiroshima and Nagasaki that hastened the end of the war.

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Boeing B-50D Superfortress. Note the more powerful engines, enlarged vertical stabilizer, and external fuel tanks. Developed from the WWII-era B-29, the B-50 served until 1965. (US Air Force)

While most WWII-era bombers were retired with the end of the war in 1945, the technologically advanced Superfortress continued its career and flew bombing missions in the Korean War. As the KB-29, it served as the basis for one of the first aerial refueling tankers, and the upgraded B-50 served until 1965, primarily in the reconnaissance role. It also formed the basis for the Boeing C-97 Stratofreighter, the Boeing 377 Stratocruiser passenger airliner and the Pregnant/Super Guppy series of large cargo aircraft. Though nearly 4,000 Surperfortresses were produced, only two remain flying today.

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Short Takeoff


The destroyed Titan II missile silo following the explosion (Author unknown)

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September 19, 1980 – A Titan II intercontinental ballistic missile explodes in its silo in Damascus, Arkansas. While performing routine maintenance on the Titan II missile, a member of the two-man propellant transfer system (PTS) team dropped an 8-pound socket which fell 80 feet and struck the missile, piercing the first-stage fuel tank. The puncture caused a leak of the aerozine 50 fuel, which would ignite if it came in contact with the nitrogen tetroxide used as an oxidizer. At 3:00 am, the mixture ignited, blowing off the 740-ton silo door and ejecting the second stage, with its W53 warhead, roughly 100 feet outside of the missile complex. The launch station was completely destroyed, but the safety measures on the warhead prevented it from detonating. Senior Airman David Livingston, who had entered the silo prior to the explosion, was killed, and 21 others were seriously injured.


(US Air Force)

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September 19, 1969 – The first flight of the Mil Mi-24, a large and heavily armed helicopter gunship that is also capable of carrying eight passengers or troops. With armament to provide close air support (CAS) and room to transport soldiers, the Mi-24 (NATO reporting name Hind) is essentially a flying infantry fighting vehicle. The Mi-24 was developed from the earlier Mil Mi-8, and has a heavily armored fuselage and titanium rotor blades that can withstand hits from 12.7mm rounds. 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.


(NASA)

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September 19, 1962 – The first flight of the Aero Spacelines Pregnant Guppy, an oversized cargo aircraft that was developed from the Boeing 377 Stratocruiser. Aero Spacelines founder and former USAF pilot John Conroy conceived the idea, and obtained former Pan Am and BOAC Stratocruisers to construct the giant cargo hauler. The addition of the large cargo area gave the Pregnant Guppy a triple-bubble cross section which could carry 50,000 pounds of cargo, and was used to transport 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. The original Pregnant Guppy was scrapped in 1979.


(Adrian Balch, Ulster Aviation Society)

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September 19, 1949 – The first flight of the Fairey Gannet. The Gannet arose out of a 1945 Admiralty requirement for a turboprop-powered antisubmarine warfare (ASW) and strike aircraft. The Gannet had a crew of three and was powered by an Armstrong Siddeley Double Mamba engine, which consisted of two turboprop engines mounted side-by-side and turning a contra-rotating propeller via a gearbox. After the Gannet entered service in the ASW role, it was further developed into AEW.1 Airborne Early Warning (AEW) variant to replace the Douglas AEW.1 Skyraider and made the first carrier deck landing by a turboprop aircraft on 1950. When the ASW mission was taken over by helicopters, some Gannets transitioned to the carrier onboard delivery role (COD). A total of 348 were built in both AEW and ASW variants, and they served Australia, Germany, Indonesia and the United Kingdom until their retirement in 1978.


(Bf 109 illustration by Jerry Crandall)

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September 20, 1993 – The death of Erich Hartmann. Born on April 19, 1922, Hartmann was taught to fly by his mother, one of the first female glider pilots in Germany. During WWII, Hartmann became the most successful fighter pilot in history with 352 victories to his credit, all but seven coming against Russian aircraft on the Eastern Front. Over the course of 1,404 sorties, Hartmann, known as the Blonde Knight, was never shot down or forced down by enemy fire, though he did crash land 14 times, all due to mechanical problems or damage caused by the debris from aircraft he had dispatched. Following the war, Hartmann spent 10 years in Soviet prison camps before his release in 1955, and then joined the newly-formed West German Luftwaffe as the first commander of Jagdgeschwader 71, named after Manfred von Richtofen, better known as the Red Baron. Hartmann resigned from the Luftwaffe in 1970 over his opposition to the Luftwaffe’s adoption of the Lockheed F-104G Straighter and ended his career as a flight instructor before his death at age 71.


(US Navy)

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September 20, 1951 – The first flight of the Grumman F9F (F-9) Cougar, a carrier-based fighter developed for the US Navy. Orginally conceived as an improved version of the Grumman F9F Panther, the Cougar was such a significant upgrade to its predecessor that the Navy gave it a new name, even though it was essentially a Panther with swept wings and much more powerful engines. The development of the swept-wing Cougar was spurred by the arrival of the Mikoyan-Gurevich MiG-15 over Korea, though the Panther was too late to see service in the war, and the Cougar was replaced by the Grumman F11F Tiger and Vought F8U Crusader before the outbreak of the Vietnam War. Following their retirement from Navy service, many Cougars ended their life as as QF-9 target drones.


The Gloster Meteor with turboprop engines. Note the added stabilizers on the tail, and the feathered number 2 engine. (Author unknown)

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September 20, 1945 – A modified Gloster Meteor F.1 is the first aircraft to fly under turboprop power. A single Meteor F.1, serial number EE227, had its Rolls-Royce Derwent turbojets removed and replaced with Rolls-Royce Trent turboprops. The undercarriage was lengthened to provide clearance for the 7-foot 7-inch diameter Rotol props which were turned through a reduction gear. Following its first flight, the turboprop Meteor was subsequently flown at higher power and with smaller props to help develop what was a very complicated engine control system. The testing program ended in 1948.


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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. The Vampire is notable for its twin tail design, with the engine housed in a central, egg-shaped fuselage. This arrangement shortened the tailpipe and allowed full use of the limited power available in the early turbojet engines. The Vampire entered service in 1945, where they acted as a ground attack aircraft while the Meteor took on the role of fighter. Vampires saw action in the 1948 Arab-Israeli War, the Malayan Emergency, and the Rhodesian Bush War, and were phased out by the RAF by the end of the 1950s. The last export Vampires were retired by the Rhodesian Air Force in 1979.


(NASA)

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September 21, 2012 – The Space Shuttle flies atop the Shuttle Carrier Aircraft (SCA) for the last time. With the end of the Space Shuttle program in 2011, the retired Shuttles were distributed to various museums and sites around the country. Endeavour was the last to be delivered and, during its ferry 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, it 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 where many Shuttle landings took place. 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. Endeavour is now on display at the California Science Center in Los Angeles.


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September 21, 1984 – The first flight of the Dassault Falcon 900, a business jet produced by Dassault Aviation of France and, with its sister ship the Falcon 7X, the only trijets currently in production. The Falcon 900 is the continuation of the line of Falcon jets that began with the Falcon 20 and continued with the Falcon 50. With a crew of two, the Falcon 900 can accommodate up to 19 passengers, and its three Honeywell TFE731 turbofans provide a top speed of Mach 0.87 and an intercontinental range of over 4,000 miles. More than 500 have been built since production began in 1984, and the 900 remains in production today.


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September 21, 1945 – The first flight of the Hawker Sea Fury, a fighter developed for the Royal Air Force during WWII. When the RAF canceled their order at the end of the war, the Hawker developed a carrier-based version for the Royal Navy. Powered by a Bristol Centaurus 18-cylinder radial engine, the Sea Fury was the last propeller-driven fighter to enter service with the Royal Navy and, with a top speed of 460 mph, one of the fastest single piston-engined aircraft ever built. Introduced in 1947 and sold to nine export countries, the Sea Fury saw action during the Korean War, and was flown by the Cuban Fuerza Aérea Revolucionaria (Revolutionary Air Force) during the 1961 Bay of Pigs Invasion. A total of 864 were produced, and the last Sea Furys were retired by the Burmese Air Force in 1968.


Connecting Flights


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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. You can also find more stories about aviation, aviators and airplane oddities at Wingspan.

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