Fairchild Republic YA-10A 71-1369. (U.S. Air Force)
10 May 1972: Chief test pilot Howard W. (“Sam”) Nelson made the first flight of the prototype Fairchild Republic YA-10A Thunderbolt II, 71-1369, at Edwards Air Force Base in the high desert of southern California.
the first prototype Fairchild Republic YA-10A, 71-1369, landing at Edwards Air Force Base. (U.S. Air Force)
The production A-10A Thunderbolt II is a single-place, twin engine low-wing monoplane with retractable tricycle landing gear. The airplane is 52 feet, 7 inches (16.027 meters) long with a wing span of 57 feet, 6 inches (17.526 meters), and overall height of 14 feet, 8 inches (4.470 meters). Its operating weight is 24,513 pounds (11,119 kilograms) and the maximum takeoff weight is 50,000 pounds (22,680 kilograms). This includes the operating weight plus full internal fuel, 1,350 rounds of ammunition and 18 Mk.82 bombs.
The A-10 is powered by two General Electric TF34–GE-100 engines. These are two-spool axial flow turbofans with a single stage fan section, 14-stage compressor, and 6-stage turbine. The engines produce a maximum 8,900 pounds of thrust ( kilonewtons).
A General Electric GAU-8/A Avenger autocannnon installed in a Fairchild A-10 Thunderbolt II. (U.S. Air Force)
The A-10 was designed and built around its hydraulically-operated General Electric GAU-8 Avenger 30 mm Gatling-type autocannon. The gun has 7 rotating barrels and is capable of firing at a rate of 4,300 rounds per minute. The Thunderbolt II can carry a maximum of 1,350 rounds of high explosive-incendiary or armor piercing-incendiary ammunition.
Howard Verner Nelson was born on New Year’s Eve, 31 December 1924, at Hartford Connecticut. He was the second son of Gustaf B. Nelson, a clerk, and Signe Ottilia Nelson.
Nelson entered the United States Army Air Forces on 20 November 1944, and remained on active duty in the U.S. Air Force until 28 May 1957, when he transferred to the Air Force Reserve. He rose to the rank of lieutenant colonel. He flew 105 combat missions during the Korean War.
“Sam” Nelson joined the Republic Aviation Corporation in 1960. He was assigned Republic’s chief test pilot for the F-105 Thunderchief supersonic fighter bomber. In October 1976, Nelson was promoted to Director of Flight Operations.
Nelson was killed at the Paris Air Show 3 June 1977 while demonstrating an A-10A Thunderbolt II.
Lieutenant Colonel Nelson’s remains were buried at the Arlington National Cemetery.
Fairchild Republic A-10A Thunderbolt II 75-0294 crashed on the runway at the Paris Air Show, 3 June 1977. Director of Flight Operations Howard W. Nelson died enroute to a hospital. (Unattributed)
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)
Kartveli submitted his design proposal for the XP-47B to the U.S. Army Air Corps, 12 June 1940. The prototype was ordered 6 September, and a week later, 13 September 161 production P47Bs and 602 P-47Cs were ordered. The contract was for $56,499,924. The company named the new fighter “Thunderbolt,” which had been suggested by C. Hart Miller, director of the military contracts division of Republic Aviation.
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
N401PW, the first Boeing 747-400 airliner. (The Boeing Company)
29 April 1988: Boeing test pilots James C. Loesch and Kenneth Higgins take the new Boeing 747-400, serial number 23719, registration N401PW, for its first flight from Paine Field, landing at Boeing Field 2 hours 29 minutes later.
The 747-400 was a major development of the 747 series. It had many structural and electronics improvements over the earlier models, which had debuted 18 years earlier. New systems, such as a “glass cockpit”, flight management computers, and new engines allowed it to be flown with a crew of just two pilots, and the position of Flight Engineer became unnecessary.
Roll-out, Boeing 747-400 c/n 23719. (The Boeing Company)
The most visible features of the –400 are its longer upper deck and the six-foot tall “winglets” at the end of each wing, which improve aerodynamic efficiency be limiting the formation of wing-tip vortices.
On 27 June 1988, this 747-400 set a Maximum Takeoff Weight record for airliners by lifting off at Moses Lake, Washington at 892,450 pounds (405,659 kilograms).¹ At the time of its first flight, Boeing had already received orders for 100 747-400s. It would become the most popular version, with 694 aircraft built by the time production came to an end 15 March 2007.
Cockpit of a Boeing 747-400 airliner.
The Boeing 747-400 airliner can carry between 416 and 660 passengers, depending on configuration. It is 231 feet, 10 inches (70.6 meters) long with a wingspan of 211 feet, 5 inches (64.4 meters) and overall height of 63 feet, 8 inches (19.4 meters). Empty weight is 394,100 pounds (178,800 kilograms). Maximum takeoff weight (MTOW) is 875,000 pounds (396,890 kilograms).
Northwest Boeing 747-451 N661US on approach to Osaka. (Wikipedia Commons)
While the prototype was powered by four Pratt & Whitney PW4056 turbofan engines, production airplanes could be ordered with PW4062, General Electric CF6 or Rolls-Royce RB211 engines, providing thrust ranging from 59,500 to 63,300 pounds.
The –400 has a cruise speed of 0.85 Mach (567 miles per hour, 912 kilometers per hour) and maximum speed of 0.92 Mach (614 miles per hour, 988 kilometers hour). Maximum range at maximum payload weight is 7,260 nautical miles (13,450 kilometers).
Northwest Airlines’ Boeing 747-451, N661US, on approach to Osaka Kansai International Airport, 11 June 2007. (Photograph courtesy of Dennis Lau)
After the test program was completed, the prototype 747-400 was outfitted for airline service. It was operated by Northwestern Airlines and is currently in service with Delta Air Lines. It has been re-registered as N661US, and carries the Delta fleet number 6301.
N661US was the aircraft operated as Northwest Airlines Flight 85 on 9 October 2002 when it suffered a rudder hardover while over the North Pacific Ocean. The aircraft went into a sudden 40° left bank when a hydraulic power unit for the lower rudder failed due to a fatigue fracture. This incident is considered to be an excellent example of Cockpit Resource Management (CRM) as the flight crew successfully landed the airplane at Anchorage, Alaska.
Boeing 747-451 N661US, Delta Air Lines, landing at Tokyo-Narita International Airport, 25 July 2009. (Photograph courtesy of Kazuchika Naya)
After flying its final revenue flight, 9 September 2015, as Flight 836, Honolulu to Atlanta, N661US was stored at Delta Technical Operations. It is now displayed at the Delta Flight Museum, Hartsfield Jackson International Airport.
Delta’s Ship 6301, N661US, completes its final flight, landing at Hartsfield Jackson International Airport, Atlanta, Georgia, 9 September 2015. (Delta Flight Museum)
North American Aviation test pilot George S. Welch, flying the first of three XP-86 prototypes, serial number 45-59597. (North American Aviation, Inc.)
26 April 1948: At Muroc Field (now known as Edwards Air Force Base), in the high desert of southern California, North American Aviation test pilot George Welch put the prototype XP-86 Sabre, 45-59597, into a 40° dive and broke the Sound Barrier. It is only the second U.S. aircraft to fly supersonic. The first was the Bell X-1, piloted by Chuck Yeager, only a few months earlier.
Or, maybe not.
In his book, Aces Wild: The Race For Mach 1, fellow North American Aviation test pilot Albert W. Blackburn makes the case that George Welch had taken the prototype XP-86 Sabre supersonic on its first flight, 1 October 1947, and that he had done so three times before Chuck Yeager first broke the Sound Barrier with the Bell X-1 rocketplane, 14 October 1947. Blackburn described two runs through the NACA radar theodolite with speeds of Mach 1.02 and 1.04 on 13 November 1947.
Mr. Blackburn speculates—convincingly, in my opinion—that Secretary of the Air Force W. Stuart Symington, Jr., ordered that Welch’s excursions beyond Mach 1 were to remain secret. However, during a radio interview, British test pilot Wing Commander Roland Prosper (“Bee”) Beamont, C.B.E, D.S.O. and Bar, D.F.C. and Bar, stated that he had flown through the Sound Barrier in the number two XP-86 Sabre prototype (45-59598). Once that news became public, the U.S. Air Force released a statement that George Welch had flown beyond Mach 1 earlier, but gave the date as 26 April 1948.
Test pilot George S. Welch, wearing his distinctive orange helmet, in the cockpit of the prototype XP-86. This photograph was taken 14 October 1947. (U.S. Air Force)
It wasn’t long after the first flight of the XP-86 on October 1, 1947, that Welch dropped into Horkey’s [Edward J. Horkey, an aerodynamicist at North American Aviation] office at the Inglewood plant. He wanted to talk about his recent flight and some “funny” readings in the airspeed indicator. He had made a straight-out climb to more than 35,000 feet. Then, turning back toward Muroc Dry Lake, he began a full-power, fairly steep descent.
“I started at about 290 knots,” Welch was explaining to Horkey. “In no time I’m at 350. I’m still going down, and I’m still accelerating but the airspeed indicator seems stuck like there’s some kind of obstruction in the pitot tube. I push over a little steeper and by this time I’m through 30,000 feet. All of a sudden, the airspeed indicator flips to 410 knots. The aircraft feels fine, no funny noises, no vibration. Wanted to roll off to the left, but no big deal. Still, I leveled out at about 25,000 and came back on the power. The airspeed flicked back to 390. What do you think?”
“. . . You may be running into some Mach effects. . . .”
— Aces Wild: The Race For Mach 1, by Al Blackburn, Scholarly Resources Inc., Wilmington, Delaware, 1999, at Pages 147–148.
The “funny” reading of the airspeed indicator became known as the “Mach jump.” George Welch was the first to describe it.
The Sabre became a legendary jet fighter during the Korean War. 9,860 were built by North American, as well as by licensees in Canada, Australia and Japan.
George Welch had been recommended for the Medal of Honor for his actions as a P-40 Warhawk fighter pilot in Hawaii, December 7, 1941. He was killed while testing a North American Aviation F-100A Super Sabre, 12 October 1954.
Test pilot George S. Welch with a North American Aviation F-86 Sabre. (San Diego Air and Space Museum Archives)
Grumman YA2F-1 Intruder Bu. No. 147864 with landing gear extended during the first flight, 19 April 1960. (San Diego Air and Space Museum Archives)
19 April 1960: Grumman Aircraft Engineering Corporation test pilot Robert K. Smyth made the first flight of the prototype YA2F-1 Intruder, Bu. No. 147864, at the Grumman Peconic River Airport (CTO), Calverton, Long Island, New York. During the flight, Smyth climbed to 15,000 feet (4,572 meters). The landing gear remained extended during the flight. At one point, Smyth attempted to retract it, but a malfunction was indicated, so they remained down and locked. The first flight lasted one hour.
During follow-on flights, Bob Smyth and project test pilot Ernie von der Heyden (who flew the photo-chase plane during the first flight) alternated left and right seats.
Bu. No. 147864 was painted gray with U.S. Navy markings before being accepted by the Navy on 29 April 1960. The airplane was lost 31 May 1960.
Grumman test pilot Robert K. Smyth in the cockpit of the YA2F-1 prototype, Bu. No. 147864, 29 April 1960. With Program manager Bruce Tuttle and VP Larry Mead. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)
Eight Grumman YA2F-1 Intruders were built for the test program. They were redesignated A-6A Intruder in 1962.
The Grumman A-6A Intruder was a carrier-based, all-weather attack bomber powered by two turbojet engines. It was operated by a pilot and a bombardier/navigator, or “b/n,” in a side-by-side cockpit. The wings were slightly swept.
The A2F-1 was 53 feet, 3 inches (16.231 meters) long with a wing span of 53 feet, 0 inches (16.154 meters) and overall height of 15 feet, 2 inches (4.623 meters). The wings had a total area of 528.9 square feet (49.14 square meters) and were swept aft to 25° at 25% chord. The aircraft had an empty weight of 23,412 pounds (10,620 kilograms) and maximum takeoff weight of 53,278 pounds (24,166 kilograms).
Grumman YA2F-1 Intruder, Bu. No. 147864, in Navy markings. (San Diego Air & Space Museum Archives)Grumman A2F-1 Intruder (A-6A) three-view illustration with dimensions. (U.S. Navy)
The prototypes were powered by two Pratt & Whitney J52-P-6 turbojet engines which had previously been used on the North American Aviation AGM-28 Hound Dog cruise missile. The J52 was a two-spool, axial-flow turbojet with a 12-stage compressor section (5 low- and 7 high-pressure stages) and 2-stage (1 high- and 1-low pressure stages). The engines had a normal power rating of 7,500 pounds of thrust (33.36 kilonewtons) at 11,400 r.p.m., and a maximum of 8,500 pounds (37.81 kilonewtons) at 11,650 r.p.m. The J52-P-6 was 31 inches (0.787 meters) in diameter, 127 inches (3.226 meters) long, and weighed 2,056 pounds (933 kilograms) The engine incorporated an exhaust nozzle that could be swiveled downward 23° to assist in short field takeoffs.
The A-6A had a cruise speed of 429 knots (493 miles per hour/795 kilometers per hour) at 44,450 feet (13,548 meters) and a maximum speed of 566 knots (651 miles per hour/1,048 kilometers per hour) at Sea Level. The service ceiling was 48,250 feet (14,707 meters), and the maximum range was 2,061 nautical miles (2,372 statute miles/3,817 kilometers).
The initial production Intruders could carry 18,000 pounds ( kilograms) of bombs on hardpoints under the wings. It could also carry AIM-9 Sidewinder air to air, or AGM-12 Bullpup air to ground missiles. “Special Weapons” that could be carried included Mk. 28 or Mk. 43 thermonuclear bombs.
The Intruder was a very successful combat aircraft with 693 built in attack, tanker and electronic warfare variants. They remained in service with the United States Navy until 1997.
Grumman YA2F-1 (A-6A) Intruder Bu. No. 147867, the third prototype, carrying thirty Mk. 82 low-drag 500-pound bombs on multiple ejector racks under the wings and fuselage. (U.S. Navy)
