7 May 1937: First flight of the Lockheed XC-35, Air Corps serial number 36-353. Ordered by the Air Corps in 1936 as a high-altitude research aircraft, and for the development of cabin pressurization, the XC-35 Supercharged Cabin Transport Airplane was a highly modified Lockheed Electra 10A. It was the first airplane to be specifically built with a pressurized cabin.
The Army Air Corps was awarded the Collier Trophy for 1937 for the XC-35 project.
With a strengthened circular fuselage and smaller windows, the XC-35′s passenger compartment was pressurized by engine turbo-superchargers and controlled by a flight engineer. Cabin pressure could be maintained at the equivalent of 12,000 feet (3,658 meters) above sea level, at an actual altitude of 30,000 feet (9,144 meters).
A crew of three and two passengers were accommodated within the pressurized section, and there was room for another passenger to the rear of the pressure bulkhead, which could only be used at lower altitudes.
Lockheed XC-35 36-353.
The Lockheed XC-35 was powered by two air-cooled, supercharged, 1,343.804-cubic-inch-displacement (22.021 liter) Pratt & Whitney R-1340-43 (Wasp T5H1) single-row, nine-cylinder radial engines with a compression ratio of 6:1. The R-1340-43 had a Normal and Takeoff Power rating of 550 horsepower at 2,200 r.p.m. from Sea Level to 3,000 feet (914 meters), burning 92-octane gasoline. It was direct drive. The engine was 3 feet, 6.25 inches (1.073 meters) long, 4 feet, 3.50 inches (1.308 meters) in diameter, and weighed 864 pounds (392 kilograms).
Able to fly above 30,000 feet (9,144 meters), the XC-35 was later used by NACA for thunderstorm penetration research flights. In 1948 it was transferred to the Smithsonian Institution.
“1st April 1936: English aviator Amy Mollison, nee Johnson (1903 – 1941) wearing a woollen suit from the collection of flight clothes designed by Madame Schiaparelli for her solo flight from London to Cape Town. (Photo by Sasha/Getty Images)”
4–7 May 1936: British aviatrix Amy Johnson, C.B.E., departed Gravesend Aerodrome, Kent, England, at 8:02 a.m. GMT, 4 May 1936, in her Percival D.3 Gull Six, registration G-ADZO, enroute to Cape Town, South Africa. In July 1932, she had set a record for flying this route, solo, breaking the existing record which had been set by her husband, James Mollison. The current record, though, was held by Flight Lieutenant Tommy Rose. Her goal was to retake the record.
During the next three days, Johnson flew approximately 6,700 miles (10,782 kilometers). She made several stops to refuel her airplane, but she slept only about six hours.
She arrived at Wingfield Aerodrome, Cape Town, at 2:31 p.m. GMT, 7 May, for an elapsed time of 3 days, 6 hours, 29 minutes. Her average speed over the course was 122.65 kilometers per hour (76.21 miles per hour), setting a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a Recognized Course.¹ She broke Tommy Rose’s time by 11 hours, 9 minutes. Her plan was to then make the return flight and beat Rose’s two-way record.
Amy Johnson’s record-breaking Percival D.3 Gull Six, G-ADZO, at Gravesend. (Science Museum/Science and Society Picture Library)
Amy Johnson’s Percival D.3 Gull Six, c/n D63, was a single-engine, low-wing monoplane, with fixed landing gear, designed by Edgar Percival and built by Percival Aircraft Limited at Gravesend. It was built primarily of wood and covered by doped fabric. The Gull was flown by a single pilot and could carry two passengers.
The airplane was 24 feet, 9 inches (7.544 meters) long with a wingspan of 36 feet, 2 inches (11.024 meters) and height of 7 feet, 4½ inches (2.248 meters). The D.3 had an empty weight of 1,170 pounds (530.7 kilograms) and gross weight of 2,050 pounds (929.9 kilograms).
The Gull Six was powered by an air-cooled, normally-aspirated 9.186 liter (560.57-cubic-inch-displacement) air-cooled de Havilland Gypsy Six I, an inverted, inline six-cylinder engine which produced 184 horsepower at 2,100 r.p.m., and 205 horsepower at 2,350 r.p.m. for takeoff. The engine turned a two-bladed fixed-pitch propeller via direct drive. The engine weighed 432 pounds (196 kilograms).
The Gull Six was capable of reaching 178 miles per hour (286.5 kilometers per hour). Its service ceiling was 16,000 feet (4,876.8 meters) and range was 700 miles (1,126.5 kilometers).
G-ADZO had been sold to Harold Leslie Brook, 12 December 1935. Amy Johnson had flown it in a previous attempt for the London-Cape Town record in April 1936, but G-ADZO was seriously damaged when she ground-looped the airplane at Colomb-Béchar, French Algeria.
The Gull was raced by R. Falk, flying for the Marquess of Londonderry, in the King’s Cup, 10–11 July 1936, carrying race number 12. G-ADZO finished in 7th place with a time of 2 hours, 10 minutes 48 seconds, and average speed of 163.44 miles per hour (263.03 kilometers per hour).
In 1937, H. L Brook flew G-ADZO to Capetopwn and back.
G-ADZO was scrapped 8 February 1938.
G-ADZO in the water at King’s Lynn.Percival Aircraft Company advertisement in FLIGHT, 21 May 1936. (Aviation Ancestry Database of British Aviation Advertisements 1909–1980)
Amy Johnson had set many flight records, both individually and with her husband, James Mollison, whom she had married in 1932 (divorced, 1938). He proposed to her during an airplane flight, only eight hours after having met her. For her record-setting flight from England to Australia in May 1931, she was made Commander of the Most Excellent Order of the British Empire (CBE) and won the Harmon Trophy.
During World War II, Amy Johnson flew for the Royal Air Force as a First Officer of the Air Transport Auxiliary (equivalent to the RAF rank of Flight Lieutenant). Tragically, on 5 January 1941, while flying over London, she was challenged by an RAF fighter. Twice she gave the incorrect recognition code and she was then shot down. Her airplane crashed into the Thames, where she was seen struggling in the water. Lieutenant Commander Walter Fletcher of HMS Haslemere dived into the river to rescue her, but both died. This incident was kept secret and it was publicly reported that she had run out of fuel.
6 May 1959: Vsevolod Vladimirovich Vinitsky (Всеволод Владимирович Виницкий), with Sergei P. Sanayev, flew a Kamov Ka-15 coaxial helicopter to set a Fédération Aéronautique Internationale (FAI) World Record for Speed Over a Closed Circuit of 500 Kilometers Without Payload. The helicopter’s average speed over the course was 170.45 kilometers per hour (105.92 miles per hour).¹
Kamov Ka-15
The Ka-15 was a single-engine, two-place, light helicopter, flown by a single pilot. The protototype first flew 14 April 1953, with Dmitry Konstantinovich Efremov, chief test pilot for the Kamov Design Bureau. The helicopter used two fully-articulated, three-bladed, counter-rotating coaxial rotors. The helicopter had two vertical fins mounted at the ends of a horizontal stabilizer, and four-wheeled fixed landing gear.
Kamov Ka-15. (Soldat.Pro)
The fuselage of the Ka-15 was 6.26 meters (20 feet, 6.5 inches) long. The main rotors’ diameter was 9.96 meters (32 feet, 8.1 inches), and the overall height of the the helicopter was 3.35 meters (10 feet, 11.9 inches). The span of the horizontal stabilizer and vertical fins were 2.85 meters (9 feet, 4.2 inches). The Ka-15 had an empty weight of 996 kilograms (2,196 pounds), normal takeoff weight of 1,360 kilograms (2,998 pounds), and maximum takeoff weight (MTOW) of 1,460 kilograms (3,219 pounds).
Kamov Ka-15. (Alchetron)
The rotors turn at 333 r.p.m. The upper rotor turned clockwise, as seen from above. (The advancing blade is on the left), and the lower blades turn counter-clockwise (their advancing blades are on the right). The area of the main rotor disc was 155.83 square meters (1,677.29 square feet) with a solidity ratio of 3% per rotor. (This is the lowest coefficient of disc area of any helicopter.) Each main rotor blade was trapezoidal, with a theoretical chord at the axis of rotation of 300 millimeters (11.8 inches), narrowing to 100 millimeters (3.9 inches) at the blade tip. The blades incorporated 12° of negative twist.
Kamov Ka-15. (Soldat.pro)
The Ka-15 was powered by a single air-cooled, supercharged 10.131 liter (618.234 cubic inches) Ivchenko AI-14V nine-cylinder radial engine with a compression ratio of 5.9:1. The engine was rated at 188 kilowatts (252 horsepower). It weighed approximately 200 kilograms (441 pounds).
The helicopter could carry a single passenger or 364 kilograms (802 pounds) of cargo. (Interestingly, the contemporary single main rotor/tail rotor Mil Mi-1 helicopter required 575 horsepower to lift the same payload as the Ka-15.)
The Ka-15 had a cruise speed 120 kilometers per hour (75 miles per hour) and maximum speed 155 kilometers per hour (96 miles per hour). The service ceiling was 3,500 meters (11,483 feet). It could hover out of ground effect (HOGE) at 600 meters (1,969 feet). The helicopter had a normal range of 278 kilometers (173 miles) and maximum range of 520 kilometers (323 miles).
The performance of the Ka-15 was better than had been predicted. After several years of testing, the Ka-15 entered production in 1956. It was the first mass-produced coaxial helicopter, with approximately 375 being built by Aircraft Factory No. 99 at Ulan-Ude, the capitol city of the Buryat-Mongolian Autonomous Soviet Socialist Republic.
Nikolai Ilich Kamov
In a coaxial rotor system, one rotor is placed above the other, with the drive shaft for the upper rotor inside the hollow drive shaft of the lower. As in tandem rotor helicopters, each counter-rotating rotor counteracts the torque effect of the other. There is no anti-torque rotor (tail rotor) required. In helicopters using a tail rotor, as much as 30% of engine power is required to drive the tail rotor. With counter-rotating rotors, all of the engine’s power can be used to provide lift and thrust.
A second benefit of a coaxial rotor is that the dissymetry of lift of each rotor is also canceled out. There is no translating tendency while in a hover, and higher forward speeds are possible because the effect of retreating blade stall is reduced. A helicopter with coaxial rotors is more compact than a similar helicopter with tandem rotors. This makes it useful for operations in confined areas or aboard ships.
Nikolai Ilich Kamov was previously known for his autogyro designs, which were first produced in 1929. These included the Tsentralniy Aerogidrodinamicheskiy Institut (Central Aero-Hydrodynamic Institute) TsAGI A-7, which was the first armed autogyro. The Kamov Design Bureau was established 7 October 1948 at Lyubertsy, near Moscow, Russia.
The Kamov A-7 autogyro was armed with two 7.62 mm machine guns machine guns and could carry four 100 kilogram bombs or six TS-82 rockets under the fuselage.Vsevolod Vladimirovich Vinitsky
Vsevolod Vladimirovich Vinitsky was born 11 February 1915 at Omsk, Akmola, Imperial Russia. In 1932, he graduated from the Ural Geological Prospecting Technical School at Chelyabinsk, and in 1933 Sverdlovsk glider school. Vsevolod Vladimirovich attended the Polar Aviation Administration (Nikolaev) school of marine pilots, Glavsevmorputi, in 1939.
Vsevolod Vladimirovich entered the Red Army in 1941. He served with the 33rd Airborne Squadron (Western Front) during September and November of that year, followed by the 7th Airborne Squadron (WF); From March to Spetember 1942, he was a commander with the 7th Airborne Corps (WF). The then commanded the 2nd Airborne Regiment (Ukranian Front) until May 1944. He flew 44 combat sorties
In August 1945, Vsevolod Vladimirovich assumed command of the 51st Transport Aviation Regiment on the Transbaikal Front.
After the Great Patriotic War (World War II), Vinitsky was a pilot for Polar Aviation, then in 1950, he bacame a test pilot for Mil OKB. He made the first flights of the Mil Mi-1U and the Mi-4.
Flying a Mil Mi-1, he performed first engine-off touch-down autorotation in the Soviet Union. He perfected helicopter flight under icing and instrument meteorological conditions. He later became a test pilot at Gromov Flight Research Institute at Zhukovsky. With Dmitry Konstantinovich Efremov, Vsevolod Vladimirovich piloted the Kamov Ka-22 gyrodyne. In 1963 he worked for the TsAGI planetary station
Vsevolod Vladimirovich Vinitsky died at Moscow, 12 September 1992 at the age of 77 years. He was buried at the Kuzminsky Cemetery, Moscow.
Igor Sikorsky with his VS-300A, Stratford, Connecticut, 6 May 1941. (Sikorsky Archives)
6 May 1941: At Stratford, Connecticut, Igor Sikorsky piloted his Vought-Sikorsky VS-300 helicopter to a new world’s record for endurance. He flew for 1 hour, 32 minutes, 26 seconds. ¹ The previous record—1 hour, 20 minutes, 49 seconds—had been set by Ewald Rohlfs with the Focke-Wulf Fw 61 tandem-rotor helicopter, 25 June 1937. ²
During its development, the VS-300 went through at least 18 changes in its rotor configuration. This photograph, taken after the record-setting flight, shows an intermediate version, with one main rotor for lift and three auxiliary rotors for anti-torque and directional control.
Igor Ivanovich Sikorsky 1888–1970. Sikorsky Archives)
In the final configuration, Sikorsky arrived at what we now recognize as a helicopter, with the main rotor providing lift, thrust and roll control through variable collective and cyclic pitch, and a single tail rotor for anti-torque and yaw control.
The VS-300 had a welded tubular steel airframe and used a 28-foot (5.34 meters) diameter, fully-articulated, three-bladed main rotor, which turned clockwise (as seen from above) at 260 r.p.m. (The advancing blade was on the left. This would later be reversed.) The main rotor had collective pitch control for vertical control, but cyclic pitch (Sikorsky referred to this as “sectional control”) for directional control would not be developed for another several months.
The tail “propellers” (what we now consider to be rotors—one vertical and two horizontal) each had two blades with a diameter of 7 feet, 8 inches (2.337 meters) and turned approximately 1,300 r.p.m. The vertical rotor provided “torque compensation” (anti-torque) and the blade pitch was fully reversible. The horizontal rotors were mounted on 10-foot (3.048 meters) outriggers at the aft end of the fuselage. For lateral control, the pitch on one rotor was increased and the other decreased. For longitudinal control, the pitch of both rotors was increased or decreased together.
The VS-300 was originally equipped with an air-cooled, normally-aspirated 144.489-cubic-inch-displacement (2.368 liter) Lycoming O-145C-3 four-cylinder horizontally-opposed engine which was rated at 75 horsepower at 3,100 r.p.m. According to Mr. Sikorsky, “early in 1941,” the Lycoming engine was replaced by an air-cooled, normally-aspirated 198.608 cubic inch (3.255 liter) Franklin 4AC-199-E, a four-cylinder horizontally-opposed overhead valve (OHV) direct-drive engine with a compression ratio of 7:1, rated at 90 horsepower at 2,500 r.p.m. It is not known if this change was made prior to 6 May.
¹ During World War II, only a very few ballooning and gliding world records were certified by the Fédération Aéronautique Internationale. Although Sikorsky’s flight duration exceeded that of Rohlfs, it is not listed as an official world record.
Republic XP-47B 40-3051 prototype in flight. (Republic Aircraft Corporation)
6 May 1941: Just eight months after a prototype for a new single-engine fighter was ordered by the U.S. Army Air Forces, test pilot Lowery Lawson Brabham took off from the Republic Aviation Corporation factory airfield at Farmingdale, New York, and flew the prototype XP-47B Thunderbolt, serial number 40-3051, to Mitchel Field, New York.
During the flight, oil which had collected in the exhaust duct began burning. There was so much smoke that Brabham considered bailing out. He stayed with the prototype, though, and when he arrived at Mitchel Field, he exclaimed, “I think we’ve hit the jackpot!”
Alexander Kartveli
The prototype was designed by Alexander Kartveli, a Georgian immigrant and former chief engineer for the Seversky Aircraft Corporation, which became the Republic Aviation Corporation in 1939.
Alexander Kartveli (née Kartvelishvili, ალექსანდრე ქართველი) was born in Tbilisi, in the Kutais Governorate of the Russian Empire, (what is now, Georgia). After World War I, during which he was wounded, Kartvelishvili was sent to study at the Paris Aviation Higher College of Engineering in France by the government of the Democratic Republic of Georgia. He graduated in 1922. Kartvelishvili did not return to his country, which had fallen to the Red Army in the Soviet-Georgian War. He worked for Blériot Aéronautique S.A. until 1928, when he was employed by the Fokker American Company (also known as Atlantic Aircraft, or Atlantic-Fokker) which was headquartered at Passaic, New Jersey, in the United States. In 1931, he became chief engineer for the Seversky Aircraft Company in Farmingdale.
Republic XP-47B Thunderbolt prototype 40-3051 at Farmingdale, New York, 1941. The pilot standing in front of the airplane gives a scale reference. (Republic Aviation Corporation)
The XP-47B was the largest single-engine fighter that had yet been built. The production P-47B was 34 feet, 10 inches (10.617 meters) long with a wingspan of 40 feet, 9-5/16 inches (12.429 meters), and height of 12 feet, 8 inches (3.861 meters).¹ The wing area was 300 square feet (27.9 square meters). At a gross weight of 12,086 pounds (5,482 kilograms), it was nearly twice as heavy as any of its contemporaries.
Republic XP-47B Thunderbolt 40-3051 at Wright Field, Dayton, Ohio.(Ray Wagner Collection, San Diego Air & Space Museum Archives )
The XP-47B was powered by an air-cooled, supercharged and turbocharged, 2,804.4-cubic-inch-displacement (45.956 liter) Pratt & Whitney R-2800-21 (Double Wasp TSB1-G) two-row, 18-cylinder radial with a compression ratio of 6.65:1 had a normal power rating of 1,625 horsepower at 2,550 r.p.m., to an altitude of 25,000 feet (7,620 meters), and a takeoff/military power rating of 2,000 horsepower at 2,700 r.p.m. at 25,000 feet (7,620 meters). The engine drove a 12-foot, 2 inch (3.708 meter) diameter, four-bladed Curtiss Electric constant-speed propeller through a 2:1 gear reduction. The R-2800-21 was 4 feet, 4.50 inches (1.340 meters) in diameter and 6 feet, 3.72 inches (1.923 meters) long. The engine weighed 2,265 pounds (1,027 kilograms). Approximately 80% of these engines were produced by the Ford Motor Company. It was also used as a commercial aircraft engine, with optional propeller gear reduction ratios.
A large General Electric turbosupercharger was mounted in the rear of the fuselage. Internal ducts carried exhaust gases from the engine to drive the turbocharger. This supercharged air was then carried forward through an intercooler and then on to the carburetor to supply the engine. The engine’s mechanical supercharger further pressurized the air-fuel charge.
Republic XP-47B 40-3051. The pilot enters the cockpit through a hinged canopy segment. (Ray Wagner Collection Catalog, San Diego Air and Space Museum)
During flight testing, the XP-47B Thunderbolt demonstrated speeds of 344.5 miles per hour (554.4 kilometers per hour) at 5,425 feet (1,654 meters), and 382 miles per hour (615 kilometers per hour) at 15,600 feet (4,745 meters). Its maximum speed was 412 miles per hour (663 kilometers per hour) at 25,800 feet (7,864 meters). The test pilot reported that the engine was unable to produce full power during these tests. It was determined that it had a cracked cylinder head, resulting in a loss of 2.5–4% of its maximum rated power. Also, the XP-47B was painted in camouflage, resulting in a slight loss of speed.
It could climb to 15,000 feet (4,572 meters) in just five minutes.
The Thunderbolt was armed with eight Browning AN-M2 .50-caliber machine guns, four in each wing, with 3,400 rounds of ammunition. It could also carry external fuel tanks, rockets and bombs. The structure of the P-47 could be described as “robust” and it was heavily armored. The amount of damage that the airplane could absorb and still return was remarkable.
Republic XP-47B Thunderbolt 40-3051, 4 May 1941. (Republic Aviation Corporation)
During a test flight, 4 August 1942, the XP-47B’s tail wheel was left down. The extreme heat of the turbocharger’s exhaust set fire to the tire, which then spread to the airplane’s fabric-covered control surfaces. Unable to control the airplane, test pilot Filmore L. Gilmer bailed out. The prototype Thunderbolt crashed into Long Island Sound and was destroyed.
The third production Republic P-47B Thunderbolt, 41-5897, at Langley Field, Virginia, 24 March 1942. The door-hinged canopy of the XP-47B has been replaced by a rearward-sliding canopy, requiring that the radio antenna mast be moved.(NASA)A Republic P-47B Thunderbolt in the NACA Full Scale Tunnel, 31 July 1942. (NASA LMAL 29051)
A total of 15,683 Thunderbolts were built; more than any other U.S. fighter type. In aerial combat, it had a kill-to-loss ratio of 4.6:1. The P-47, though, really made its name as a ground attack fighter, destroying aircraft, locomotives, rail cars, and tanks by the many thousands. It was one of the most successful aircraft of World War II.
¹ Data from Pilot’s Flight Operating Instructions, Technical Order No. 01-65BC-1, 20 January 1943
