Tag Archives: Mines Field

9 September 1940

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North American Aviation NA-73X prototype, NX19998, at Mines Field, California, 9 September 1940. (North American Aviation, Inc.)

9 September 1940: North American Aviation completed assembly of the NA-73X, the first prototype of the new Mustang Mk.I fighter for the Royal Air Force. This was just 117 days after the British Purchasing Commission had authorized the construction of the prototype. The airplane was designed by a team led by Edgar Schmued. The 1,150-horsepower Allison V-12 engine had not yet arrived, so the NA-73X was photographed with dummy exhaust stacks. The prototype’s company serial number was 73-3097. It had been assigned a civil experimental registration number, NX19998.

The NA-73X was a single-seat, single-engine, low wing monoplane with retractable landing gear. It was primarily of metal construction, though the flight control surfaces were fabric covered. The airplane was designed for the maximum reduction in aerodynamic drag.  The Mustang was the first airplane to use a laminar-flow wing. The fuselage panels were precisely designed and very smooth. Flush riveting was used. The coolant radiator with its intake and exhaust ducts was located behind and below the cockpit. As cooling air passed through the radiator it was heated and expanded, so that as it exited, it actually produced some thrust.

The prototype was 32 feet, 2⅝ inches (9.820 meters) long, with a wing span of 37 feet, 5/16 inch (11.286 meters). Empty weight of the NA-73X was 6,278 pounds (2,848 kilograms) and normal takeoff weight was 7,965 pounds (3,613 kilograms).

Aeronautical Engineer Edgar Schmued with a North American P-51-2-NA (Mustang Mk.IA), 41-37322. (San Diego Air and Space Museum Archives)

The NA-73X was powered by a liquid-cooled, supercharged, 1,710.60-cubic-inch-displacement (28.032 liter) Allison Engineering Company V-1710-F3R (V-1710-39) single overhead cam 60° V-12 engine, with four valves per cylinder and a compression ratio of 6.65:1. It used a single-stage, single-speed supercharger. This was a right-hand tractor engine (the V-1710 was built in both right-hand and left-hand configurations) which drove a 10 foot, 6 inch (3.200 meter) diameter, three-bladed, Curtiss Electric constant-speed propeller through a 2.00:1 gear reduction.

The V-1710-39 had a Normal Power rating of 880 horsepower at 2,600 r.p.m. at Sea Level; Take Off Power rating of 1,150 horsepower at 3,000 r.p.m. at Sea Level, with 44.5 inches of manifold pressure (1.51 Bar), 5 minute limit; and a War Emergency Power rating of 1,490 horsepower at 3,000 r.p.m., with 56 inches of manifold pressure (1.90 Bar). The V-1710-F3R was 7 feet, 4.38 inches (2.245 meters) long, 3 feet, 0.64 inches (0.931 meters) high, and 2 feet, 5.29 inches (0.744 meters) wide. It had a dry weight of 1,310 pounds (594 kilograms).

U.S. Army Air Corps flight tests of the fully-armed production Mustang Mk.I (XP-51 41-038), equipped with the V-1710-39 and a 10 foot, 9-inch (3.277 meters) diameter Curtiss Electric propeller, resulted in a maximum speed of 382.0 miles per hour (614.8 kilometers per hour) at 13,000 feet (3,962 meters). The service ceiling was 30,800 feet (9,388 meters) and the absolute ceiling was 31,900 feet (9,723 meters).

The Curtiss P-40D Warhawk used the same Allison V-1710-39 engine as the XP-51, as well as a three-bladed Curtiss Electric propeller. During performance testing at Wright Field, a P-40D, Air Corps serial number 40-362, weighing 7,740 pounds (3,511 kilograms), reached a maximum speed of 354 miles per hour (570 kilometers per hour) at 15,175 feet (4,625 meters). Although the Mustang’s test weight was 194 pounds (88 kilograms) heavier, at 7,934 pounds (3,599 kilograms), the Mustang was 28 miles per hour (45 kilometers per hour) faster than the Warhawk. This demonstrates the effectiveness of the Mustang’s exceptionally clean design.

Only one NA-73X was built. It made its first flight 26 October 1940 with test pilot Vance Breese. The prototype suffered significant damage when it overturned during a forced landing, 20 November 1941. NX19998 was repaired and flight testing resumed. The prototype’s final disposition is not known.

Originally ordered by Great Britain, the Mustang became the legendary U.S. Army Air Corps P-51 Mustang. A total of 15,486 Mustangs were built by North American Aviation at Inglewood, California and Dallas, Texas. Another 200 were built in Australia by the Commonwealth Aircraft Corporation.

The P-51 remained in service with the U.S. Air Force until 27 January 1957 when the last one, F-51D-30-NA 44-74936, was retired from the 167th Fighter Squadron, West Virginia Air National Guard. It was then transferred to the National Museum of the United States Air Force at Wright-Patterson Air Force Base, where it is on display.

North American Aviation NA-73X prototype, left front quarter view. (North American Aviation, Inc.)
North American Aviation NA-73X prototype, NX19998, left front quarter view. (North American Aviation, Inc.)

© 2017, Bryan R. Swopes

23–26 August 1929

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Graf Zeppelin, LZ 127, at Mines Field, Los Angeles, 26 August 1929. (M.J. Ford)
Dr. Hugo Eckener (18xx—1954)
Dr. Hugo Eckener (1868—1954)

The rigid airship Graf Zeppelin, LZ 127, under the command of Dr. Hugo Eckener, departed Lakehurst Naval Air Station, New Jersey, 8 August 1929, heading east across the Atlantic Ocean on the first aerial circumnavigation by air. The flight was sponsored by publisher William Randolph Hearst, who had placed several correspondents aboard.

Graf Zeppelin was named after Ferdinand Adolf Heinrich August Graf von Zeppelin, a German general and count, the founder of the Zeppelin Airship Company. The airship was constructed of a lightweight metal structure covered by a fabric envelope. It was 776 feet (236.6 meters) long. Contained inside were 12 hydrogen-filled buoyancy tanks, fuel tanks, work spaces and crew quarters.

A gondola mounted underneath contained the flight deck, a sitting and dining room and ten passenger cabins. The LZ-127 was manned by a 36 person crew and could carry 24 passengers.

LZ-127was powered by five water-cooled, fuel injected 33.251 liter (2,029.1 cubic inches) Maybach VL-2 60° V-12 engines producing 570 horsepower at 1,600 r.p.m., each. Fuel was either gasoline or blau gas, a gaseous fuel similar to propane. The zeppelin’s maximum speed was 80 miles per hour (128 kilometers per hour).

A dining room aboard Graf Zeppelin.
A dining room aboard Graf Zeppelin.

After refueling at the Kasumigaura Naval Air Station, Tokyo, Japan, Graf Zeppelin started east across the Pacific Ocean on 23 August, enroute to Los Angeles, California. This leg crossed 5,998 miles (9,653 kilometers) in 79 hours, 3 minutes. This was the first ever non-stop flight across the Pacific Ocean.

LZ 127 arrived at Mines Field (now, LAX) at 1:50 a.m., 26 August 1929. There were an estimated 50,000 spectators.

Airship Graf Zeppelin, D-LZ127, at Los Angeles, 1929. A Goodyear blimp is alongside.
Airship Graf Zeppelin, D-LZ127, at Los Angeles, 1929. A Goodyear blimp is alongside. (M.J. Ford)

© 2017, Bryan R. Swopes

19 August 1940

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Vance Breese (SDA&SM)

19 August 1940: At Mines Field (now known as Los Angeles International Airport), the first North American Aviation B-25 twin-engine medium bomber, serial number 40-2165, took off on its first flight with test pilot Vance Breese at the controls and engineer Roy Ferren in the co-pilot’s position.

The airplane, North American model NA-62, serial number 62-2834, was developed from two earlier designs which had been evaluated by the U.S. Air Corps but rejected, and it was ordered into production without a prototype being built.

The first few B-25s built—sources vary, but 8–10 airplanes—were built with a constant dihedral wing. Testing at Wright Field showed that the airplane had a slight tendency to “Dutch roll” so all B-25s after those were built with a “cranked” wing, with the outer wing panels having very slight dihedral ¹ and giving it the bomber’s characteristic “gull wing” appearance. The two vertical stabilizers were also increased in size.

40-2165 was retained by North American for testing while the next several aircraft were sent to Wright Field.

Roy Ferren (SDA&SM)

The B-25 was named Mitchell in honor of early air power advocate Brigadier General Billy Mitchell. A total of 9,984 B-25s, F-10 reconnaissance variants and U.S. Navy and Marine Corps PBJ-1 patrol bombers were built by North American Aviation at Inglewood, California and Kansas City, Kansas. The last one, a TB-25J, remained in service with the U.S. Air Force until 1960.

Twenty-three B-25s were built before the B-25A Mitchell went into production. The B-25 was operated by a crew of five. It was 54 feet, 1 inch (16.485 meters) long with a wingspan of 67 feet, 6.7 inches (20.592 meters) and overall height of 16 feet, 4 inches (4.978 meters). The empty weight was 17,258 pounds (7,828 kilograms) and the maximum gross weight was 28,557 pounds (12,953 kilograms).

Scale model of a North American Aviation B-25 medium bomber being tested in a wind tunnel. (4″ × 5″ Kodachrome transparency by Alfred Palmer)

The B-25 was powered by two air-cooled, supercharged, 2,603.737-cubic-inch-displacement (42.688 liter) Wright Aeronautical Division Cyclone 14 GR2600B665 (R-2600-9) two-row 14-cylinder radial engines which were rated at 1,500 horsepower at 2,400 r.p.m., and 1,700 horsepower at 2,600 r.p.m. for takeoff. These engines (also commonly called “Twin Cyclone”) drove three-bladed Hamilton Standard Hydromatic variable-pitch propellers through 16:9 gear reduction. The R-2600-9 was 5 feet, 3.1 inches (1.603 meters) long and 4 feet, 6.26 inches (1.378 meters) in diameter. It weighed 1,980 pounds (898 kilograms).

The medium bomber had a maximum speed of 322 miles per hour (518 kilometers per hour) at 15,000 feet (4,572 meters) and a service ceiling of 30,000 feet (9,144 meters). It could carry a 3,000 pound bomb load 2,000 miles (3,219 kilometers).

Defensive armament consisted of three air-cooled Browning M2 .30-caliber aircraft machine guns and one Browning AN-M2 .50-caliber machine gun.

After testing was completed, B-25 40-2165 was retained by North American and modified as a company transport. On 8 January 1945, flown by Edgar A. Stewart, the airplane suffered an engine failure and made a forced landing at Mines Field—the location of its first flight. The prototype B-25 was damaged beyond repair.

Front view of the first North American B-25 Mitchell, 40-2165. The constant dihedral wing was used on the first nine airplanes built. (U.S. Air Force)
Front view of the first North American Aviation B-25 Mitchell medium bomber, 40-2165, at Mines Field, August 1940. The constant dihedral wing was used on the first nine airplanes built. (U.S. Air Force)
North American Aviation NA-62, B-25 Mitchell 40-2165, left front. (U.S. Air Force)
North American B-25 Mitchell 40-2165, left rear. (U.S. Air Force)
North American Aviation B-25 Mitchell 40-2165, left rear. (U.S. Air Force)
North American Aviation B-25A Mitchell twin-engine medium bomber in flight near Wright Field, Ohio, 1 May 1941. (Rudy Arnold Photo Collection, Smithsonian Institution National Air and Space Museum XRA-4945)
North American Aviation B-25A Mitchell twin-engine medium bomber in flight near Wright Field, Ohio, 1 May 1941. (Rudy Arnold Photo Collection, Smithsonian Institution National Air and Space Museum XRA-4946)

¹ The wing center section of the B-25H and B-25J has 4° 38′ 23″ dihedral. The outer sections have 0° 21′ 39″. The wing has 2° 29′ 37″ negative twist.

© 2019, Bryan R. Swopes

30 July 1935

Aviation, , , ,
Northrop 3A. (Dan Shumaker Collection/1000aircraftphotos.com)
Lieutenant Arthur Henry Skaer, Jr. (David Schwind/Ancestry)

30 July 1935: The Northrop 3A was a prototype pursuit built to compete for the U.S. Army Air Corps’ fighter contract. It flew against the Curtiss-Wright Model 75 Hawk, X17Y, and the Seversky SEV-1XP, X18Y. During flight testing, the Northrop entry was found to have undesirable spin characteristics and was returned to the builder for further work.

On the afternoon of 30 July 1935, 1st Lieutenant Arthur Henry Skaer, Jr., Air Corps Reserve, who was employed by Northrop as a test pilot, took off from Mines Field (now Los Angeles International Airport, LAX) to conduct spin tests.

Skaer never returned. An extensive search was conducted of the nearby Palos Verdes Peninsula and the southern California coastal waters. An Air Corps search plane spotted what appeared to be fresh oil on the surface, but no other sign of Lieutenant Skaer or the Northrop 3A were ever found.

The United Press reported:

Mystery Airplane Of Army Missing; Hunt Under Way

Fear felt for Safety of Reserve Flier in Coast Hills

(By United Press)

     LOS ANGELES, July 30—Fear for the safety of Lieutenant Arthur Skaer, lost in a test flight in a new “mystery” pursuit plane—reportedly the fastest army plane in the world—deepened tonight when planes searching the desolate Palos Verdes hills, where he was last seen.

     Skaer, army reserve test flier, took off shortly afternoon from Mines field, and the plane has not been reported since.

Others to Search

     At dawn, planes from the sheriff’s air detail, national guard planes from the Long Beach, Cal., airport, and possibly planes from the army air base at March field, Riverside, Cal., will join the search, combing a 200-mile coastal strip from San Diego northward.

     The plane, latest weapon in army air warfare, reportedly was able to travel 300 miles an hour, and was a secret design, rigidly guarded by the U.S. army and officials of the Northrop factory, where it was built.

Last Report of Sighting

     Reports that his plane had been last seen over the Palos Verdes area between San Pedro and Venice, Cal., resulted in a search by a squad of army reserve planes from the Long Beach air base under Lieutenant John K. Nissley.

     The planes circled over the hills until after dark, but saw no sign of the Northrop. Meanwhile, Captain Claude Morgan of the sheriff’s air detail was preparing to join the search in the morning.

—The Salt Lake Tribune, Vol. 131, No. 108, Wednesday, 31 July 1935, Page 1, Column 3

—Los Angeles Times, Vol. LIV, Thursday, 1 August 1935, Page 1, Column 6 and 7

Arthur Henry Skaer, Jr., was born at Denver, Colorado, circa 1911. He was the son of Arthur Henry Skaer, Sr., purchasing agent for a manufacturing company, and Ada Jane Scott Skaer.

Skaer graduated from East High School in Denver in 1929. While there, he was a member of the student council, the track and wrestling teams, and the cooking club.

On 29 April 1935, Lieutenant Skaer married Miss Dorothy B. Firebaugh, a fellow student from East High School. They resided in Walnut Park, California.

Northrop 3A

The Northrop 3A was a single engine, single place, low wing monoplane with an enclosed cockpit and retractable landing gear. It was of all-metal monocoque construction. The airplane was 22 feet, 3 inches (6.782 meters) long with a wingspan of 34 feet, 6 inches (10.516 meters) and height of 9 feet, 1 inch (2.769 meters). It had an operational weight of 3,900 pounds (1,769 kilograms).

The Northrop 3A, photographed 30 July 1935, the day it disappeared off the coast of southern California. No trace was found of it or the pilot, 1st Lieutenant Arthur Henry Skaer, Jr. (Ray Wagner Collection, San Diego Air & Space Museum Archives, Catalog #: 16_005638)

The Northrop 3A was powered by an air-cooled, supercharged, 1,535.387-cubic-inch displacement (25.160 liters) Pratt & Whitney Twin Wasp Junior, two-row, 14-cylinder radial engine. The specific model is not known but most sources state that it was rated at 700 horsepower.

The prototype was unarmed, but was planned to carry a single .30-caliber or .50-caliber machine gun.

Northrop 3A

© 2023, Bryan R. Swopes