Tag Archives: Test Pilot

13 January 1942

Heinkel He 280 V-1 DL+AS with engine intake fairings.

13 January 1942:

“. . .The first ejection seats were developed independently during World War II by Heinkel and SAAB. Early models were powered by compressed air and the first aircraft to be fitted with such a system was the Heinkel He 280 prototype jet-engined fighter in 1940. One of the He 280 test pilots, Helmut Schenk, became the first person to escape from a stricken aircraft with an ejection seat on 13 January 1942 after his control surfaces iced up and became inoperable. The fighter, being used in tests of the Argus As 014 impulse jets for Fieseler Fi 103 missile development, had its usual HeS 8A turbojets removed, and was towed aloft from Rechlin, Germany by a pair of Bf 110C tugs in a heavy snow-shower. At 7,875 feet (2,400 m), Schenk found he had no control, jettisoned his towline, and ejected. . . .”

—Wikipedia

Heinkel He 280 V1, DL+AS, the first prototype. The engine intakes and exhausts are faired over. This aircraft was lost 13 January 1942. Helmut Schenk successfully ejected from it. (Unattributed)
A Heinkel He 111 bomber tows the prototype He 280 V1 DL+AS on a snowy runway.
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10 January 1964

Boeing B-52H-170-BW 61-023
A Boeing B-52H Stratofortress similar to 61-023. (U.S. Air Force)

10 January 1964: This Boeing B-52H Stratofortress, serial number 61-023, flown by Boeing test pilot Charles F. (“Chuck”) Fisher, was conducting structural testing in turbulence near East Spanish Peak, Colorado. The other crew members were pilots Richard V. Curry and Leo Coer, and navigator James Pittman. Dick Curry was flying the airplane and Chuck Fisher, the aircraft commander, was in the co-pilot’s position. Pittman was on the lower deck.

The bomber was carrying two North American Aviation GAM-77 Hound Dog cruise missiles on pylons under its wings.

The Boeing B-52 Stratofortress had been designed as a very high altitude penetration bomber, but changes in Soviet defensive systems led the Strategic Air Command to change to very low altitude flight as a means of evading radar. This was subjecting the airframes to unexpected stresses. “Ten-Twenty-Three” (its serial number was 61-023, shortened on the vertical fin to “1023”) had been returned to Boeing Wichita by the Air Force to be instrumented to investigate the effects of high-speed, low-altitude flight on the 245-ton bomber.

Flying at 14,300 feet (4,359 meters) and 345 knots (397 miles per hour, 639 kilometers per hour), indicated air speed, the airplane encountered severe clear air turbulence and lost the vertical stabilizer. Several B-52s had been lost under similar circumstances. (Another, a B-52D, was lost just three days later at Savage Mountain, Maryland.)

East Spanish Peak (left), 12,688 feet (3,867 meters) and West Spanish Peak, 13,626 feet (4,153 meters), Sangre de Cristo Mountains, Colorado. (Footwarrior)
East Spanish Peak (left), 12,688 feet (3,867 meters) and West Spanish Peak, 13,626 feet (4,153 meters), Sangre de Cristo Mountains, Colorado. (Footwarrior)
Charles F. Fisher. (Argenta Images)
Charles F. Fisher. (Argenta Images)

Chuck Fisher immediately took control of the B-52. He later reported,

“As the encounter progressed, a very sharp-edged blow which was followed by many more. We developed an almost instantaneous rate of roll at fairly high rate. The roll was to the far left and the nose was swinging up and to the right at a rapid rate. During the second portion of the encounter, the airplane motions actually seemed to be negating my control inputs. I had the rudder to the firewall, the column in my lap, and full wheel, and I wasn’t having any luck righting the airplane. In the short period after the turbulence I gave the order to prepare to abandon the airplane because I didn’t think we were going to keep it together.”

A Boeing report on the incident, based on installed sensors and instrumentation aboard -023, said that the bomber had

“. . . flown through an area containing the combined effects of a (wind) rotor associated with a mountain wave and lateral shear due to airflow around a mountain peak. . . Gust initially built up from the right to a maximum of about 45 feet per second [13.7 meters per second](TAS), then reversed to a maximum of 36 feet per second [11 meters per second] from the left, before swinging to a maximum of about 147 feet per second [44.8 meters per second] from the left followed by a return to 31 feet per second [9.5 meters per second].”

Fisher flew the bomber back to Wichita and was met by a F-100 Super Sabre chase plane. When the extent of the damage was seen, the B-52 was diverted due to the gusty winds in Kansas. Six hours after the damage occurred, Chuck Fisher safely landed the airplane at Eaker Air Force Base, Blythville, Arkansas. He said it was, “the finest airplane I’ve ever flown.”

Boeing B-52H-170-BW Stratofortress 61-023, "Ten-Twenty-Three", after losing the vertical fin, 10 January 1964. (Boeing)
Boeing B-52H-170-BW Stratofortress 61-023, “Ten-Twenty-Three”, after losing the vertical fin, 10 January 1964. (Boeing)

61-023 was repaired and returned to service. It remained active with the United States Air Force until it was placed in storage at Tinker Air Force Base, Oklahoma, 24 July 2008.

Charles F. Fisher and the Boeing test crew with B-52H Stratofortress 61-023. (Boeing)
Charles F. Fisher at left,  and the Boeing test crew with B-52H Stratofortress 61-023. (Boeing)

The B-52H is a sub-sonic, swept wing, long-range strategic bomber. It has a crew of five. The airplane is 159 feet, 4 inches (48.6 meters) long, with a wing span of 185 feet (56.4 meters). It is 40 feet, 8 inches (12.4 meters) high to the top of the vertical fin. Maximum Takeoff Weight (MTOW) is 488,000 pounds (221,353 kilograms).

There are eight Pratt & Whitney TF33-PW-3 turbofan engines mounted in two-engine pods suspended under the wings on four pylons. Each engine produces a maximum of 17,000 pounds of thrust (75.620 kilonewtons). The TF-33 is a two-spool axial-flow turbofan engine with 2 fan stages, 14-stage compressor stages (7 stage intermediate pressure, 7 stage high-pressure) and and 4-stage turbine (1 stage high-pressure, 3-stage low-pressure). The engine is 11 feet, 10 inches (3.607 meters) long, 4 feet, 5.0 inches (1.346 meters) in diameter and weighs 3,900 pounds (15,377 kilograms).

The B-52H can carry approximately 70,000 pounds (31,750 kilograms) of ordnance, including free-fall bombs, precision-guided bombs, thermonuclear bombs and cruise missiles, naval mines and anti-ship missiles.

The bomber’s cruise speed is 520 miles per hour (837 kilometers per hour) and its maximum speed is 650 miles per hour (1,046 kilometers per hour) at 23,800 feet (7,254 meters) at a combat weight of 306,350 pounds. Its service ceiling is 47,700 feet (14,539 meters) at the same combat weight. The unrefueled range is 8,000 miles (12,875 kilometers).

With inflight refueling, the Stratofortress’s range is limited only by the endurance of its five-man crew.

The B-52H is the only version still in service. 102 were built and as of 27 September 2016, 76 are still in service. Beginning in 2013, the Air Force began a fleet-wide technological upgrade for the B-52H, including a digital avionics and communications system, as well as an internal weapons bay upgrade. The bomber is expected to remain in service until 2040.

Boeing B-52H-170-BW Stratofortress 61-023 taxiing at Minot Air Force Base, North Dakota. (Senior Airman Cassandra Jones, U.S. Air Force)
Boeing B-52H-170-BW Stratofortress 61-023 taxiing at Minot Air Force Base, North Dakota. (Senior Airman Cassandra Jones, U.S. Air Force)

© 2016, Bryan R. Swopes

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8 January 1944

Lockheed XP-80 prototype, 44-83020, at Muroc AAF, 8 January 1944. (U.S. Air Force)
The Lockheed XP-80 prototype, 44-83020, at Muroc Army Air Field, 8 January 1944. (Lockheed Martin Aeronautics Company)
Milo Burcham
Milo Garrett Burcham

8 January 1944: At Muroc Army Air Field (later to become Edwards Air Force Base), the Lockheed Aircraft Corporation’s chief engineering test pilot, Milo Garrett Burcham, took the prototype Model L-140, the Army Air Forces XP-80 Shooting Star, 44-83020, for its first flight.

Tex Johnston, who would later become Boeing’s Chief of Flight Test, was at Muroc testing the Bell Aircraft Corporation XP-59 Airacomet. He wrote about the XP-80’s first flight in his autobiography:

Early on the morning of the scheduled first flight of the XP-80, busload after busload of political dignitaries and almost every general in the Army Air Force arrived at the northwest end of the lake a short distance from our hangar. Scheduled takeoff time had passed. I was afraid Milo was having difficulties. Then I heard the H.1B fire up, and he taxied by on the lake bed in front of our ramp. What a beautiful bird—another product of Kelly Johnson, Lockheed’s famed chief design engineer—tricycle gear, very thin wings, and a clear-view bubble canopy. Milo gave me the okay sign.

This was the initial flight of America’s second jet fighter, and what a flight it was. Milo taxied along in front of generals and politicians, turned south and applied full power. I could see the spectators’ fingers going in their ears. The smoke and sand were flying as the engine reached full power, and the XP-80 roared down the lake. Milo pulled her off, retracted gear and flaps, and held her on the deck. Accelerating, he pulled up in a climbing right turn, rolled into a left turn to a north heading, and from an altitude I estimated to be 4,000 feet [1,219 meters] entered a full-bore dive headed for the buses. He started the pull-up in front of our hangar and was in a 60-degree climb when he passed over the buses doing consecutive aileron rolls at 360 degrees per second up to 10,000 feet [3,048 meters]. He then rolled over and came screaming back. He shot the place up north and south, east and west, landed and coasted up in front of the spectators, engine off and winding down. I have never seen a crowd so excited since my barnstorming days. I returned to the office and dictated a wire to [Robert M.] Stanley [Chief Test Pilot, Bell Aircraft Corporation]WITNESSED LOCKHEED XP-80 INITIAL FLIGHT STOP VERY IMPRESSIVE STOP BACK TO DRAWING BOARD STOP SIGNED, TEX I knew he would understand.

Tex Johnston: Jet-Age Test Pilot, by A.M. “Tex” Johnston with Charles Barton, Smithsonian Books, Washington, D.C., 1 June 1992, Chapter 5 at Pages 127–128.

A few minor problems caused Burcham to end the flight after approximately five minutes but these were quickly resolved and flight testing continued.

The XP-80 was the first American airplane to exceed 500 miles per hour (805 kilometers per hour) in level flight.

Clarence L. "Kelly" Johnson with a scale model of a Lockheed P-80A-1-LO Shooting Star. Johnson's "Skunk Works" also designed the F-104 Starfighter, U-2, A-12 Oxcart and SR-71A Blackbird. (Lockheed Martin Aeronautical Company)
Clarence L. “Kelly” Johnson with a scale model of a Lockheed P-80A-1-LO Shooting Star. Johnson’s “Skunk Works” also designed the F-104 Starfighter, U-2, A-12 Oxcart and SR-71A Blackbird. (Lockheed Martin Aeronautics Company)

The Lockheed XP-80 was designed by Clarence L. “Kelly” Johnson and a small team of engineers that would become known as the “Skunk Works,” in response to a U.S. Army Air Corps proposal to build a single-engine fighter around the de Havilland Halford H.1B Goblin turbojet engine. (The Goblin powered the de Havilland DH.100 Vampire F.1 fighter.)

Lockheed Aircraft Corporation was given a development contract which required that a prototype be ready to fly within just 180 days.

Milo Burcham, on the left, shakes hands with Clarence L. Johnson following the first flight of the Lockheed XP-80, 8 January 1944. (Lockheed)
Milo Burcham, on the left, shakes hands with Clarence L. Johnson following the first flight of the Lockheed XP-80, 8 January 1944. (Lockheed Martin Aeronautics Co.)

The XP-80 was a single-seat, single-engine airplane with straight wings and retractable tricycle landing gear. Intakes for engine air were placed low on the fuselage, just forward of the wings. The engine exhaust was ducted straight out through the tail. For the first prototype, the cockpit was not pressurized but would be on production airplanes.

As was customary for World War II U.S. Army Air Forces aircraft, the prototype was camouflaged in non-reflective Dark Green with Light Gull Gray undersides. The blue and white “star and bar” national insignia was painted on the aft fuselage, and Lockheed’s winged-star corporate logo was on the nose and vertical fin. Later, the airplane’s radio call, 483020 was stenciled on the fin in yellow paint. The number 20 was painted on either side of the nose in large block letters. Eventually the tip of the nose was painted white and a large number 78 was painted just ahead of the intakes in yellow block numerals. Early in the test program, rounded tips were installed on the wings and tail surfaces. This is how the XP-80 appears today.

Lockheed XP-80 parked at Muroc Dry Lake, 1944 (Lockheed)
The highly-polished Dark Green and Light Gull Gray Lockheed XP-80 prototype parked at Muroc Dry Lake, 1944 (Lockheed Martin Aeronautics Co.)

The XP-80 is 32 feet, 911/16 inches (9.9997 meters) long with a wingspan of 37 feet, ⅞-inch (11.2998 meters) and overall height of 10 feet, 21/16 inches (3.1004 meters). It had a Basic Weight for Flight Test of 6,418.5 pounds (2,911.4 kilograms) and Gross Weight (as actually weighed prior to test flight) of 8,859.5 pounds (4,018.6 kilograms).

The Halford H.1B Goblin used a single-stage centrifugal-flow compressor, sixteen combustion chambers, and single-stage axial-flow turbine. It had a straight-through configuration rather than the reverse-flow of the Whittle turbojet from which it was derived. The H.1B produced 2,460 pounds of thrust (10.94 kilonewtons) at 9,500 r.p.m., and 3,000 pounds (13.34 kilonewtons) at 10,500 r.p.m. The Goblin weighed approximately 1,300 pounds (590 kilograms).

Cutaway illustration of the Halford H.1B Goblin turbojet engine. (FLIGHT and AIRCRAFT ENGINEER)

The XP-80 has a maximum speed of 502 miles per hour (808 kilometers per hour) at 20,480 feet (6,242 meters) and a rate of climb of 3,000 feet per minute (15.24 meters per second). The service ceiling is 41,000 feet (12,497 meters).

Unusual for a prototype, the XP-80 was armed. Six air-cooled Browning AN-M2 .50-caliber machine guns were placed in the nose. The maximum ammunition capacity for the prototype was 200 rounds per gun.

The Halford engine was unreliable and Lockheed recommended redesigning the the fighter around the larger, more powerful General Electric I-40 (produced by GE and Allison as the J33 turbojet). The proposal was accepted and following prototypes were built as the XP-80A.

Lockheed built 1,715 P-80s for the U.S. Air Force and U.S. Navy. They entered combat during the Korean War in 1950. A two-seat trainer version was even more numerous: the famous T-33A Shooting Star.

Lockheed XP-80 Shooting Star 44-83020 was used as a test aircraft and jet trainer for several years. In 1949, it was donated to the Smithsonian Institution. 44-83020 is on display at the Jet Aviation exhibit of the National Air and Space Museum. It was restored beginning in 1976, and over the next two years nearly 5,000 man-hours of work were needed to complete the restoration.

The prototype Lockheed XP-80 Shooting Star, 44-83020, at teh Smithsonian Institution National Air and Space Museum. (NASM)
The prototype Lockheed XP-80 Shooting Star, s/n 140-1001, 44-83020, at the Smithsonian Institution National Air and Space Museum. (NASM)

© 2019, Bryan R. Swopes

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5 January 1956

Piasecki YH-16A-PH Transporter 50-1270 hovers in ground effect.
Piasecki YH-16A-PH Transporter 50-1270 hovers in ground effect. (Piasecki Aircraft Corporation)

5 January 1956: The prototype Piasecki Helicopter Company YH-16A-PH Transporter twin-turboshaft, tandem-rotor helicopter, serial number 50-1270, was returning to Philadelphia from a test flight, when, at approximately 3:55 p.m., the aft rotor desynchronized, collided with the forward rotor and the aircraft broke up in flight. It crashed at the Mattson Farm on Oldman’s Creek Road, near Swedesboro, New Jersey, and was completely destroyed.

Test pilots Harold W. Peterson and George Callahan were killed.

It was determined that a bearing associated with an internal coaxial shaft supporting test data equipment had seized, causing the rotor shaft to fail.

Harold W. Peterson (left) and George Callahan, with the prototype Piasecki YH-16A Turbo Transporter, 50-1270. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)
Harold W. Peterson (left) and George Callahan, with the prototype Piasecki YH-16A Turbo Transporter, 50-1270. (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers)

At the time, the YH-16 was the largest helicopter in the world. The United States Air Force intended it as a very-long-range rescue helicopter, while the U.S. Army expected it to serve as a heavy lift cargo and troop transport.

The YH-16A had a fuselage length of 78 feet (23.774 meters), and both main rotors were 82 feet (24.994 meters) in diameter. With rotors turning, the overall length was 134 feet (40.843 meters). Their operating speed was 125 r.p.m. Overall height of the helicopter was 25 feet (7.62 meters). The helicopter’s empty weight was 22,506 pounds (10,209 kilograms) and the gross weight was 33,577 pounds (15,230 kilograms).

YH-16 50-1269 was powered by two 2,181.2-cubic-inch-displacement (35.74 liter) air-cooled, supercharged Pratt & Whitney Twin Wasp E2 (R-2180-11) two-row, fourteen-cylinder radial engines with a Normal Power Rating of 1,300 horsepower at 2,600 r.p.m. at 8,000 feet (2,438 meters), and 1,650 horsepower at 2,600 r.p.m., for Takeoff.

The second YH-16A, 50-1270, was modified while under construction and was powered by two Allison Division YT38-A-10 turboshaft engines which produced 1,800 shaft horsepower, each. This made the YH-16A the world’s first twin-engine turbine-powered helicopter.

The Piasecki YH-16A Transporter was the world's largest helicopter in 1956. (Piasecki Aircraft Corporation)
The Piasecki YH-16A Transporter was the world’s largest helicopter in 1956. (Piasecki Aircraft Corporation)

The cruise speed of the YH-16A was 146 miles per hour (235 kilometers per hour). In July 1955, Peterson and Callahan had flown 50-1270 to an unofficial record speed of 165.8 miles per hour (266.83 kilometers per hour). The service ceiling was 19,100 feet (5,822 meters) and the maximum range for a rescue mission was planned at 1,432 miles (2,305 kilometers).

After the accident, the H-16 project was cancelled.

Prototype Piasecki YH-16A Transporter 50-1270, hovering in ground effect at Philadelphia Airport, 1955. (Piasecki Aircraft Corporation)
Prototype Piasecki YH-16A Transporter 50-1270, hovering in ground effect at Philadelphia Airport, 1955. (Piasecki Aircraft Corporation)

© 2017, Bryan R. Swopes

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31 December 1938

Boeing Model 307 Stratoliner with all engines running, Boeing Field, Seattle, Washington, circa 1939. (San Diego Air & Space Museum Archives)

31 December 1938: Boeing Model 307 Stratoliner NX19901 made its first flight at Boeing Field, Seattle, Washington. The test pilot was Eddie Allen, with co-pilot Julius A. Barr.

The Model 307 was a four-engine commercial airliner that used the wings, tail surfaces, engines and landing gear of the production B-17B Flying Fortress heavy bomber. The fuselage was circular in cross section to allow for pressurization. It was the first pressurized airliner and because of its complexity, it was also the first airplane to include a flight engineer as a crew member.

Boeing 307 Stratoliner NX19901 with both propellers on right wing feathered. (Boeing)
Boeing 307 Stratoliner NX19901 with both propellers on right wing feathered. (Boeing)

The Associated Press news agency reported:

Test Of Big Craft Begins

     SEATTLE, Dec. 31—(AP)—The world’s first plane, designed for flying in the sub-stratosphere, the new Boeing “Stratoliner”, performed “admirably” in a 42-minute first test flight in the rain today.

     The big ship, with a wingspread of 107 feet, three inches, climbed to 4,000 feet, the ceiling, and cruised between here, Tacoma and Everett. Speed was held down to 175 miles an hour.

     “The control and stability and the way it handled were very nice,” Edmund T. Allen, pilot, said. “She performed admirably.”

     The 33-passenger ship was built to fly at altitudes of 20,000 feet.

     No more tests are planned until next week. The supercharging equipment for high altitude flights will be installed later.

Arizona Republic, Vol. IL, No. 228, Sunday, 1 January 1939, Page 2, Column 4

Boeing Model 307 Stratoliner NX19901 taking of at Boeing Field, Seattle, Washington. (San Diego Air & Space Museum Archives)

On March 18, 1939, during its 19th test flight, the Stratoliner went into a spin, then a dive. It suffered structural failure of the wings and horizontal stabilizer when the flight crew attempted to recover. NX19901 was destroyed and all ten persons aboard were killed.

Boeing Model 307 Stratoliner NX19901. (San Diego Air & Space Museum Archives)
Boeing Model 307 Stratoliner NX19901. (San Diego Air and Space Museum Archive, Catalog # 01 00091288)
Boeing Model 307 Stratoliner NX19901. The engine cowlings have been removed. The inboard right engine is running. The arrangement of passenger windows differs on the right and left side of the fuselage. (San Diego Air & Space Museum Archives)

The Boeing Model 307 was operated by a crew of five and could carry 33 passengers. It was 74 feet, 4 inches (22.657 meters) long with a wingspan of 107 feet, 3 inches (32.690 meters) and overall height of 20 feet, 9½ inches (6.337 meters). The wings had 4½° dihedral and 3½° angle of incidence. The empty weight was 29,900 pounds (13,562.4 kilograms) and loaded weight was 45,000 pounds (20,411.7 kilograms).

Cutaway illustration of a Boeing Model 307 Stratoliner. (NASM SI-89-4024)

The airliner was powered by four air-cooled, geared and supercharged, 1,823.129-cubic-inch-displacement (29.875 liter) Wright Cyclone 9 GR-1820-G102 9-cylinder radial engines with a compression ratio of 6.7:1, rated at 900 horsepower at 2,200 r.p.m., and 1,100 horsepower at 2,200 r.p.m. for takeoff. These drove three-bladed Hamilton-Standard Hydromatic propellers through a 0.6875:1 gear reduction in order to match the engine’s effective power range with the propellers. The GR-1820-G102 was 4 feet, 0.12 inches (1.222 meters) long, 4 feet, 7.10 inches (1.400 meters) in diameter, and weighed 1,275 pounds (578 kilograms).

Boeing Model 307 Stratoliners under construction. (SDASM Archives Catalog #: 00061653)

The maximum speed of the Model 307 was 241 miles per hour (388 kilometers per hour) at 6,000 feet (1,828.8 meters). Cruise speed was 215 miles per hour (346 kilometers per hour) at 10,000 feet (3,048 meters). The service ceiling was 23,300 feet (7,101.8 meters).

Boeing Model 307 Stratoliner NX19901 with all engines running. (San Diego Air and Space Museum Archive, Catalog # 01 00091291)
Boeing Model 307 Stratoliner NX19901 with all engines running. (San Diego Air & Space Museum Archives)
A Transcontinental and Western Airlines (TWA) Boeing 307 Stratoliner with cabin attendants. (TWA)
A Transcontinental and Western Airlines (TWA) Boeing 307 Stratoliner with cabin attendants. (Trans World Airlines)

During World War II, TWA sold its Stratoliners to the United States government which designated them C-75 and placed them in transatlantic passenger service.

Boeing C-75 Stratoliner. (San Diego Air and Space Museum Archive, Catalog # 01 00091316)
Boeing C-75 Stratoliner “Comanche,” U.S. Army Air Corps serial number 42-88624, formerly TWA’s NC19905. (San Diego Air & Space Museum Archives)
Two TWA stewardesses with a Boeing 307 Stratoliner, circa 1950. (San Diego Air & Space Museum)

In 1944, the 307s were returned to TWA and they were sent back to Boeing for modification and overhaul. The wings, engines and tail surfaces were replaced with those from the more advanced B-17G Flying Fortress. The last one in service was retired in 1951.

Of the ten Stratoliners built for Pan Am and TWA, only one remains. Fully restored by Boeing, NC19903 is at the Stephen F. Udvar-Hazy Center of the Smithsonian Institution.

The only existing Boeing Model 307 Stratoliner, NC19903, Clipper Flying Cloud, at the Smithsonian Institution National Air and Space Museum, Steven F. Udvar-Hazy Center. (Photo by Dane Penland, National Air and Space Museum, Smithsonian Institution)
The only existing Boeing Model 307 Stratoliner, NC19903, Clipper Flying Cloud, at the Smithsonian Institution National Air and Space Museum, Steven F. Udvar-Hazy Center. (Photo by Dane Penland, National Air and Space Museum, Smithsonian Institution)
Boeing Model 307 Stratoliner NX19903 after upgrade, circa 1945. (Boeing)

© 2019, Bryan R. Swopes

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