Welcome to This Date in Aviation History, getting of you caught up on milestones, important historical events and people in aviation from June 24 through June 26.
June 25, 1946 – The first flight of the Northrop YB-35. Heavy, strategic bombing reached its heyday during WWII, and some of the greatest technological advances of the era were made in the design of long-range bombers that could carry increasingly heavier payloads at ever greater distances. While work was underway on the Boeing B-29 Stratofortress, arguably the greatest of the piston-powered heavy bombers to come out of the war, the US Army Air Corps issued a request to the aviation industry for a new bomber that would be capable of reaching occupied Europe in the event that Britain fell to the Nazis. The bomber would need to be capable of carrying 10,000 pounds of bombs on a round-trip mission of 10,000 miles, with a maximum speed of 450 mph and a service ceiling of 45,000 feet.
Both Boeing and Consolidated responded, with Consolidated offering the B-36 Peacemaker, a huge six-engine bomber wouldn’t be ready for service until after the war. Northrop was eventually included in the competition, but Jack Northrop took a more radical approach, hoping to extend the range and payload of their bomber by making it as aerodynamically efficient as possible. Since any part of an aircraft that moves through the air produces drag, Northrop believed that the best way to reduce drag was to eliminate any part of the aircraft that doesn’t generate lift, particularly the fuselage and tail. The result of this design concept was a plane that was no more than a flying wing. The center section of the wing contained the cockpit and crew quarters, including bunks for off-duty pilots on long missions. A large, protruding tail cone housed the targeting equipment along with defensive machine guns. In all, Northrop planned for 20 machine guns or cannons housed in six turrets.
Since the flying wing was such a radical departure from traditional design, Northrop first developed the Northrop N-9M, a twin-engine, one-third scale flying wing which was used to gather data on flight characteristics of the design and also to act as a trainer for the YB-35 pilots. The full-sized YB-35 was powered by four Pratt & Whitney R-4360 Wasp Major radial engines each turning a contra-rotating propeller. The untested engines and propellers were supplied by the US Army, and they soon displayed significant vibration issues which proved to be so severe that Jack Northrop grounded the bomber until the problems could be fixed. Even though the YB-35 had greater range than the B-36, the Air Force deemed propeller engines obsolete by the late 1940s and ordered that Northrop modify the YB-35 to be fitted instead with eight turbojet engines, leading to the flying wing’s reclassification as the YB-49.
The jet engines gave the bomber the flight performance the Air Force desired, but the range was cut nearly in half, and the flying wing no longer had the capability to reach overseas targets from the US. It also proved very difficult to fly. Though the Air Force had originally contracted for 200 YB-35 bombers, only 13 were built, and only one ever flew. After testing proved its airworthiness, the innovative bomber was parked for more than a year before being scrapped in 1949. Two of the airframes were converted to the YB-49, one of which crashed. All the remaining airframes were scrapped.
While Jack Northrop was convinced that it was a political conspiracy that ended the flying wings, it was was also likely a case of an idea that was simply too far ahead of its time. In 1981, when Northrop was frail and near death, the Northrop Grumman team working on the B-2 Spirit flying wing bomber brought him to the factory and showed him the plans and a scale model of the B-2 at a time when the project was still top secret. Northrop’s poor health had left him unable to speak, but he reportedly wrote on a piece of paper, “Now I know why God has kept me alive for 25 years.” He died 10 months later, perhaps feeling vindicated for his unyielding belief that his flying wing would one day become a reality.
June 26, 1948 – The Berlin Airlift begins. Following the D-Day landings in France on June 6, 1944, Germany found itself squeezed on two fronts. The Allies were methodically pushing eastward on a broad front throughout Europe, while the Russians were racing westward at a breakneck pace to reach the German capital ahead of the Western Allies. Berlin fell to the Russians on May 2, 1945 and, as had been decided at the Yalta Conference held in February of that year, the German capital was divided into four occupation zones. The Russians controlled the eastern quarter of the city, while the remainder was divided between the French, British, and Americans. The city itself was deep inside eastern Germany, which was fully controlled by the Russians.
Though the shooting war was over, the Cold War between the Western Bloc (the US and its European allies) and Russia had begun. The fragile wartime alliance between the West and the Soviet Union ended, and both sides sought to influence the political makeup of Europe and the rest of the world through economic and political policies and proxy wars. On June 24, 1948, in an effort to make the city of Berlin entirely its own, Russia cut off the western sectors from the outside world, severed water connections, and halted all vehicular and river traffic into or out of the Allied sectors. West Berlin was effectively cut off from the rest of Western Europe, and it became a democratic island inside Communist East Germany. But while the Russians could block all road, rail, and water access to West Berlin, they could not put a roof over the city, so the Western allies began the greatest airlift in history.
Prior to the blockade, the Russians agreed to let the Western allies use three air corridors from western Germany into Berlin, and these corridors formed the supply routes. Starting haphazardly at first, the operation was taken over by US Brigadier General Joseph Smith, who had commanded Boeing B-29 Superfortresses under General Curtis LeMay during the war. But Smith had no airlift experience, and he was soon replaced by Major Gerneral William Tunner, a veteran of airlift operations over the Himalayas during the fight against Japan. Tunner cobbled together an aerial armada of Douglas C-47 Skytrains and British C-47 Dakotas, Douglas DC-3 airliners, and Douglas C-54 Skymasters and started round-the-clock flights. Directed by radio beacons, the Americans flew loops into Berlin’s Tempelhof Airport, while the British flew a circuit through the RAF airfield at Gatow. Tunner instituted strict rules to streamline the operation, such as requiring IFR landings regardless of weather, and eliminating aircraft stacking while planes awaited landing. If an aircraft missed an approach, the crew was required to return to their starting point, fully laden, and try again. Tunner required air crews to stay with their planes at all times, and meals were brought out to the crews on the tarmac so they could take off immediately after unloading. Citizens of West Berlin pitched in to help unload the planes.
By the end of August 1948, 1,500 flights per day—one landing every minute—delivered more than 5,000 tons of cargo, enough to keep the city fed and powered in spite of the Soviet blockade. And on Easter Sunday, 1949, the airlift managed to deliver 13,000 tons of cargo, including the equivalent of 600 railroad cars of coal. The airlift continued for 11 months and made more than 189,000 flights totaling nearly 600,000 hours of flying and amassing more than 92 million miles. In the face of this herculean effort, the Soviets finally relented and lifted the blockade one minute after midnight on May 12, 1949. West Berlin remained a free city, and it stood as an important symbol of the West’s resolve to fight the spread of Communism in Europe until the reunification of Germany in 1990.
June 26, 1942 – The first flight of the Grumman F6F Hellcat. When the US Navy entered WWII, their primary carrier-based fighter was the Grumman F4F Wildcat, a fighter that, while an all-metal monoplane, was still very much a product of an earlier era of fighters. It was only one generation removed from the Grumman F3F, the last biplane fighter to serve the Navy, and the Wildcat xeven shared the F3F’s hand-cranked landing gear. While the Wildcat did yeoman’s work in the early days of the war, it was completely outclassed by the excellent Mitsubishi A6M Zero that ruled the skies in the Pacific. Fortunately for the Navy, a successor was waiting in the wings, a fighter that had been undergoing development since 1938, and one that would prove every bit the match for the nimble Zero.
Soon after the Wildcat made its first flight on September 2, 1937, and even before it entered Navy service, Grumman started working on its successor. By June 1941, six months before the Japanese attack on Pearl Harbor, a prototype was ready for testing. And while the Hellcat bore a significant resemblance to the Wildcat, it was in fact an entirely new aircraft. Gone was the hand-cranked landing gear, replaced by hydraulically actuated struts that folded fully into the wing. The wings were mounted closer to the bottom of the fuselage and could be hydraulically folded back for carrier storage. It was also five feet longer, had a greater wingspan, and outweighed the Wildcat by 3,000 pounds. But most importantly, it had a much more powerful engine.
As development of the Hellcat continued, Grumman got valuable input from pilots who had faced the Zero in combat. As a direct result of those meetings, the Hellcat’s original Wright R-2600 Twin Cyclone radial, which produced 1,700 hp, was replaced with a Pratt & Whitney R-28900 Double Wasp 18-cylinder radial capable of 2,200 hp, the same engine that powered the Vought F4U Corsair and Republic P-47 Thunderbolt. The new power plant gave the Hellcat a top speed of 391 mph compared to the Zero’s 332 mph. While the Zero was designed to be light and agile, it offered little to no protection for the pilot. Grumman, on the other hand, a company that earned its nickname “The Iron Works” for their reputation for building rugged aircraft, gave the Hellcat a bullet-resistant windscreen, 212 pounds of cockpit armor to protect the pilot, and self-sealing fuel tanks, weight increases that were offset by the more powerful engine. The Hellcat’s claws were six .50 caliber Browning AN/M2 machine guns mounted in the wings, and it could carry up to 4,000 pounds of bombs, rockets or torpedoes.
The F6F entered service in 1943, and despite the fact that it was slower than the Corsair, it was better suited to carrier operations. Therefore, the Hellcat became the standard US Navy fighter until the end of the war. When tested against a captured A6M5 Zero, the Hellcat proved to be faster, could outturn the Japanese fighter at higher altitudes, and had a faster roll rate. The Zero was still a better dogfighter at lower altitudes, but American pilots learned to use the Hellcat’s weight and firepower to their advantage in diving attacks on Japanese fighters. The Fleet Air Arm (FAA) of the Royal Navy also flew the Hellcat, first called the Gannet, before switching back to the name Hellcat for simplicity. The 1,200 aircraft flown by the FAA served in Norway, the Mediterranean, and the Far East, but had far fewer opportunities to shoot down enemy fighters than their American counterparts in the Pacific. By the end of the war, Navy and Marine pilots calmed 5,163 victories over Japanese aircraft at a loss of 270 Hellcats, a ratio of 19:1 when taking into account both claimed and confirmed victories. There were no less than 305 pilots who became aces in the F6F.
After the war, Hellcats were used as second-line fighters behind the Grumman F8F Bearcat, and also served as trainers and even as pilotless radio-controlled bombs during the Korean War. A night fighter variant flew for the US Navy until 1954, and the Hellcat served as the original aircraft for the US Navy’s Blue Angels flight demonstration team when the team was formed in 1946. Grumman turned out more than 12,000 Hellcats in three years of production, and the final Hellcats were retired from service with the Uruguayan Navy in 1960.
June 24, 1960 – The first flight of the Hawker Siddeley HS 748, a turboprop-powered airliner originally developed by Avro to replace the Douglas DC-3. Designed for short takeoff and landing (STOL) and the ability to operate from rough, unimproved airfields, the HS 748 was envisioned as a smaller competitor to the four-engine Vickers Viscount and was capable of accommodating up to 40 passengers. The two Rolls-Royce Dart engines gave the HS 748 a cruising speed of 281 mph, and subsequent variants allowed for up to 58 passengers. A total of 380 were produced between 1961-1988, and roughly 20 remain in service today.
June 25, 1997 – The first flight of the Kamov Ka-52 Alligator, a two-seat variant of the Kamov Ka-50 attack helicopter. Following tests that compared the single-seat Ka-50 and the existing Mil Mi-28 gunship, Kamov determined that it would be cheaper to develop their existing helicopter into a more capable ground attack and reconnaissance helicopter than create a new one. The second crew member, seated beside the pilot, operates the the radar and targeting equipment, leaving the pilot free to fly the aircraft. Production began in 1996, and 80 have been built to date. The Alligator has seen action as recently as 2015 during Russia’s support of the Syrian government in the ongoing Syrian Civil War.
June 25, 1947 – The first flight of the Boeing B-50 Superfortress, an upgraded variant of the Boeing B-29 Superfortress that was fitted with more powerful engines, a lengthened fuselage, an enlarged stabilizer, and was constructed from a lighter aluminum alloy to save weight. The B-50 was never used as a bomber, but the RB-50 reconnaissance variant was flown extensively to probe the northern reaches of the Soviet Union during the Cold War, and the KB-50 tanker variant served as an early aerial refueling platform, eventually receiving a pair of General Electric J47 turbojet engines to help it keep pace with faster jet fighters. Following the introduction of the Boeing B-47 Stratojet and B-52 Stratofortress, the B-50 was retired in 1965.
June 25, 1944 – The first flight of the Ryan FR Fireball, a mixed-propulsion fighter that was powered by a Wright R-1820 Cyclone radial engine in the front and a General Electric J31 turbojet in the rear. The fuselage ultimately proved too weak for carrier operations, and the aircraft was known to break in half when coming down on the carrier deck. Despite modifications to strengthen the fuselage, production of the unfortunately-named Fireball was canceled with the end of WWII after only 66 aircraft were built. The Fireball is notable as the first jet-powered aircraft to land on a carrier, but that was only because its radial engine had failed in flight. By August 1947, all Fireballs were removed from service and most were scrapped. Only one remains, and is on display at the Planes of Fame Air Museum in California.
June 25, 1928 – The first flight of the Boeing P-12, the last biplane fighter developed by Boeing. The P-12 was intended as a replacement for the Boeing F2B and F3B fighters built for the US Navy, and its use of corrugated aluminum control surfaces and fabric-covered aluminum tube fuselage meant that it was faster and more nimble than its predecessors, even though it used the same Pratt & Whitney R-1340 Wasp radial engine. Known as the F4B in US Navy service, the P-12 entered service in 1930 and was flown by frontline fighter pursuit groups until 1935, when it was replaced by the all-metal Boeing P-26 Peashooter monoplane. The US Army flew a total of 366 P-12s, while 187 F4Bs served the Navy. Four were built for civilian customers, one of which was purchased by Howard Hughes.
June 25, 1919 – The first flight of the Junkers F.13, the world’s first all-metal transport aircraft. German aircraft designer Hugo Junkers pioneered the use of corrugated duralumin airplane skins, and his unbraced monoplane design was well ahead of other fabric-covered biplanes of the era. The F.13 carried four passengers in an enclosed, heated cabin, and the pilots sat in an enclosed cockpit. Junkers sold his aircraft abroad, and some were built under license in the US and flown by the US Post Office Department. Others were converted to float planes. To sell more aircraft, Junkers started his own airline, Junkers Luftverkehr in 1921. A total of 332 F.13s were built between 1919-1932, and four remain today in museums, with a fifth undergoing restoration.
June 26, 1974 – The first flight of the Eurocopter AS350 Écureuil (Squirrel), a single-engine light utility and transport helicopter developed by Aérospatiale as a replacement of the Aérospatiale Alouette II. The Alouette’s initial successor, the Gazelle, was a success in the military market, so the Écureuil was directed at the civilian market, and steps were taken to keep the cost of the helicopter as low as possible. The production helicopter is powered by a Turbomeca Arriel 2B turboshaft engine which gives the Écureuil a cruising speed of 152 mph, and the helicopter has capacity for five passengers. Nearly 4,000 have been produced, and the Écureuil is operated all over the world and is particularly popular with civil authorities.
June 26, 1936 – The first flight of the Focke-Wulf Fw 61, a tandem-rotor helicopter that is considered the first practical and functional helicopter. While Igor Sikorsky is known for his groundbreaking work with single-rotor helicopters, the Fw 61 used two counter-rotating, three-bladed rotors to provide lift, while lateral control was achieved by the use of cyclic pitch and asymmetric rotor lift. Torque was controlled through the counter-rotation of the rotors, and a small propeller at the front served only to cool the engine. Two were built, and one was flown famously by Hanna Reitsch inside the Deutschlandhalle in 1938. The Fw 61 also set an unofficial altitude record of 11,234 feet in 1938.
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