Tag Archives: Northrop Aircraft Inc.

25 June 1946

Northrop XB-35 taking of at Northrop Field, Hawthorne, California. (U.S. Air Force)
Northrop XB-35 taking off at Northrop Field, Hawthorne, California. (U.S. Air Force)
Max R. Stanley (Photograph courtesy of Neil Corbett, Test and Research Pilots, Flight Test Engineers))

25 June 1946: Northrop Aircraft, Inc., experimental test pilot Max R. Stanley and flight engineer Dale Schroeder made the first flight of the Northrop XB-35 “Flying Wing,” serial number 42-13603. They took off from the factory’s airfield at Hawthorne, California, and flew the prototype bomber to Muroc Army Air Field (now, Edwards Air Force Base). The initial flight lasted 55 minutes.

The Los Angeles Times reported:

On June 25, 1946, Stanley piloted the first Flying Wing, the B-35, which was a four-engine 172-foot-long, boomerang-shaped craft, from Northrop’s Hawthorne Airport to what was then the Muroc Army airfield east of Palmdale.

Emerging from the cockpit after the 55-minute flight, Stanley told The Times: “She handled beautifully.”

But taxiing along the rabbit-infested Hawthorne runway, he had had momentary doubts, he conceded 50 years later: “I looked out and I was not gaining speed on this rabbit. I thought, either something’s wrong or that’s one hell of a fast rabbit.”

Flight test crew of Northrop's XB-35 at Northrop Field, Hawthorne, California, 1946.
The flight test crew of the Northrop XB-35 at Northrop Field, Hawthorne, California, 1946. Max Stanley is just to the left of center. (Unattributed)

The XB-35 was designed as an aerodynamically efficient heavy bomber. It had a very unusual configuration for an aircraft of that time. There was no fuselage or tail control surfaces. The crew compartment, engines, fuel, landing gear and armament was contained within the wing. It was 53 feet, 1 inch (16.180 meters) long, with a wingspan of 172 feet (52.426 meters) and overall height of 20 feet, 1 inch (6.121 meters). The prototype weighed 89,560 pounds (40,624 kilograms) empty, with a gross weight of 180,000 pounds (81,647 kilograms).

The Wing defined the airplane. It had an aspect ratio of 7.4:1. The wing’s root chord was 37 feet, 6 inches (11.430 meters). The wing was 7 feet, 1.5 inches (2.172 meters) thick at the root. The tip chord was 9 feet, 4 inches (2.844 meters). There was 0° angle of incidence at the root, with -4° of twist, and 0° 53′ dihedral. The leading edge was swept aft 26° 57′ 48″, and the trailing edge, 10° 15′ 22″. The wing’s total area was 4,000 square feet (371.6 square meters).

This view of the Northrop XB-35 Flying W 42-13603 on the ramp at Muroc Air Force Base shows the pusher arrangement of four-bladed contra-rotating propellers. In the background, a turbojet-powered YB-49 is in a right bank.. (U,S. Air Force)
This view of the first prototype Northrop XB-35, 42-13603, the “Flying Wing,” on the ramp at Muroc Air Force Base shows the pusher arrangement of four-bladed contra-rotating propellers. In the background, a turbojet-powered Northrop YB-49 is in a steep bank. (U.S. Air Force)

The XB-35 was powered by four air-cooled, supercharged and turbocharged 4,362.49 cubic-inch-displacement (71.49 liter) Pratt & Whitney Wasp Major TSB1P-RGD (R-4360-17 or  -21) four-row 28-cylinder radial engines with a compression ratio of 7:1. The R-4360-17 was rated at 2,500 horsepower at 2,550 r.p.m at 40,000 feet (12,192 meters), and 3,000 horsepower at 2,700 r.p.m., for takeoff. It could maintain the takeoff rating to an altitude of 40,000 feet (12,192 meters) for Military Power. The engines were mounted completely inside the wing and were connected to a remote propeller drive unit by drive shafts. The engines were direct drive, while the propeller gear boxes had a 0.381:1 reduction ratio. The R-4360-17 was 5 feet, 7.00 inches (1.702 meters) long, 4 feet, 4.50 inches (1.334 meters) in diameter, and weighed 3,306 pounds (1,499.6 kilograms).

Northrop XB-35 42-13603 in flight with early contra-rotating propellers. (U.S. Air Force)

The propellers were dual three-bladed contra-rotating assemblies located in pusher configuration at the wing’s trailing edge. (These were quickly changed to four-bladed propellers, which were smoother in operation and more efficient.)

Northrop XB-35 42-13603. (U.S. Air Force)
Northrop XB-35 42-13603. (U.S. Air Force)

The XB-35 had a cruising speed of 183 miles per hour (295 kilometers per hour) at 39,700 feet (12,100 meters) and maximum speed was 391 miles per hour (629 kilometers per hour) at 35,000 feet (10,668 meters). With a crew of nine, and another six relief crewmembers, the bomber had a range of 8,150 miles (13,116 kilometers).

The production Northrop B-35 would have been armed with twenty .50-caliber machine guns for defense and a maximum bomb load of 51,200 pounds (23,223 kilograms).

The XB-35 was plagued by unresolved problems with the propeller gear boxes which eventually forced Jack Northrop to ground the aircraft until the engine and propeller manufacturers could come up with a solution, which was to change from piston to turbojet engines. That version became the YB-49. Because of the continuing problems, though, 42-13603 was grounded after only 19 flights, and with its sister ship, XB-35 42-38323, was scrapped in August 1949.

Northrop XB-35 in flight. (U.S. Air Force)
A Northrop XB-35 in flight. (U.S. Air Force)

© 2018, Bryan R. Swopes

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