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A Look Back at…Northrop Flying Wings - Part 1

  • Published
  • By Tony R. Landis
  • Air Force Materiel Command History Office

Northrop’s latest aircraft, the B-21A Raider, is the culmination of John K. Northrop’s dream of all-wing design, which evolution stretches back to 1929. This is the first in a series of articles that will take a look back to the early days of aviation to show the birth of John Northrop’s dream.

The Avion (Northrop) Model 1, commonly known as the 1929 Flying Wing, was the first rudimentary attempt at an all-wing vehicle, though it retained a simple boom-mounted tail assembly for added stability. Breaking away from the standard protocol of using wood for the structural assembly, Northrop chose 24S Alclad aluminum for the Model-1. Powered by a 90 HP 4 cylinder, inline, inverted Cirrus engine center-mounted inside the fuselage in a pusher (rear mounted) arrangement, the Avion Model 1 made its first flight at Mines Field, California on July 30, 1929 when test pilot Eddie Bellande performed two short hops during high speed taxi runs. Shortly thereafter the aircraft was trucked to Muroc Dry Lake in California’s Mojave Desert. The vast expanse of the dry lake gave the small test team plenty of room to test their new design.

The first ‘official’ flight of the Model-1 came on September 26 at Muroc. Bellande performed two brief flights totaling five minutes on the 26th, and three days later made its final Muroc flight during a five minute test hop around the lakebed before operations moved to United Air Terminal in Burbank where flight operations continued on November 18. 

Though the Model 1 only flew for just over a year, it underwent significant design changes to improve performance. The retractable landing gear replaced by fixed gear, tail dragger to tricycle gear arrangement, rudder extensions added for better directional stability and the pusher Cirrus engine swapped for a Menasco A-4 tractor (front mounted) arrangement. Northrop found the Model 1 to have remarkable maneuverability and performance with speeds 25% greater than contemporary designs of similar power and capacity.

The following year, the Great Depression took its toll on Jack Northrop and his new company an as a result, he notified the Civil Aeronautics Authority (the predecessor of today’s FAA) that flight testing of the Model 1 would cease on September 22, 1930. Northrop dismantled the small craft and it would be another 10 years before he could pursue his dream of all-wing design.

In 1939, after years of working for others and attempting to restart his company, John Northrop finally acquired the funding and talent to open up the new Northrop Aircraft Inc.

Their first project, the N-1, was a twin-engine all-wing medium bomber with drooped wingtips in place of conventional vertical stabilizers with a wingspan around 81 ft. Northrop completed various design studies but none seemed to interest the US Government enough to gain a contract. Northrop instead chose to make the N-1 a subscale proof-of-concept demonstrator referred to as a flying mockup.

Northrop designated the new vehicle as the N-1M (M for Mockup), an internally funded project that contained many unique features, built specifically for flight testing. The drooped wingtips could be manually adjusted on the ground to different angles in order to test stability of the airframe. The outer wing sections could also be manually adjusted on the ground to different degrees of sweep. Initially powered by two Lycoming 0-145, four-cylinder engines with 65 HP each driving two-bladed propellers, the small craft of 17 feet in length and 38 feet in span, was significantly underpowered and the engines were replaced with two Franklin 6AC264F2 six-cylinder, air-cooled engines producing 117 HP and driving three-bladed propellers.

In the summer of 1940, with construction and ground testing completed, Northrop trucked the N-1M to Baker Dry Lake in the Mojave Desert for initial flight testing. Once again, the first flight occurred during a high-speed taxi test on July 3 when the airplane hit a bump in the lakebed and became airborne for several hundred feet. Pilot Vance Breeze found the N-1M to be fully controllable before settling back down on the lakebed. The underpowered Lycomings could get the 4,000 pound aircraft into the air, but couldn’t get the vehicle above five feet in altitude. Even with modifications to the airframe, the craft could only reach 10 feet above the lakebed. With the new Franklin engines installed, the N-1M flight and altitude performance greatly improved.

Breeze made the initial flights on the N-1M before handing the craft over to Moye Stephens for continued testing. John Myers later joined Stephens on the flight test program and along with numerous single flights by guest pilots, the N-1M continued to fly into early 1943. It is estimated that the N-1M made approximately 100 flights before being retired. The restored N-1M now has a rightful place in the collection of the Smithsonian National Air & Space Museum.

Northrop engineers used the knowledge and experience from the N-1M project on their next all-wing design, the N-9.

In April 1941, the U.S. military sent out a bid request to industry for a bomber with a 10,000-pound payload capacity and 10,000-mile range. Northrop submitted several variants of their N-9 design with the N-9E being accepted for further study. Northrop received a contract for one full-sized mockup and one test aircraft on October 30, 1941. Allocated the project number of MX-140, the new bomber designation became XB-35. A second test aircraft was added to the contract the following month. (The XB-35 and YB-49 are covered in a future segment)

Northrop engineers quickly decided a one-third scale flying mockup could assist with finalizing details for the new bomber. With a 60-foot wingspan, the two Menasco C6S-4 air-cooled engines each producing 269 HP gave the N-9M a top speed of 257 mph at 7,000 feet with a service ceiling of 19,500 feet. Prior to construction of the first prototype, two additional N-9M’s were added to the contract and given the designations of N-9M-1, N-9M-2 and N-9MA.

Flight testing of the new prototypes began when Northrop test pilot John Myers took the N-9M-1 up on its first flight on December 27, 1942. Engine reliability issues limited flight times on the new vehicle. Northrop pilot Max Constant replaced Myers early in the test program when Myers was needed for other test programs. Barely six months into the test program, the N-9M-1 crashed, taking the life of Constant when control reversal pinned the control column to his chest preventing bailout.

The test program called for a replacement airframe and Northrop built the N-9MB with uprated and more reliable Franklin XO-540-7 engines of 300 HP each. The new aircraft made its first flight on January 26, 1945. Clamshell, split flap drag rudders had been installed on the wingtips of N9M-1 and N9M-2, whereas the N-9MA and N-9MB utilized split drag rudders on the trailing edge and a pitch trimmer for improved performance.

The three N-9M’s tested various control systems planned for use on the upcoming XB-35, but were slowly retired after the Aircraft Projects Section at Wright Field determined the aircraft had satisfied all test requirements. Prior to being placed in storage, guest pilots were allowed the opportunity to fly the N-9M’s. Lt. Van Shepard and Capt. Glen Edwards were among those invited to check out in the flying wing prototype. Edwards stated, “The airplane flew surprisingly well, was more stable and handled far better than most would expect.” Records are slim on the N-9M at this point and it is believed the last flight of an N-9M took place in late 1946 or early 1947. All three airframes became the property of the Northrop Aeronautical Institute and little is known as to the actual disposition of the N-9M-2 and N-9MA. The N-9MB survived, and after an extensive restoration by volunteers at the Chino Air Museum, the little plane took to the skies once again on November 8, 1994. After many years of flying on the airshow circuit, the sole surviving N-9MB crashed during a test flight on April 22, 2019 in Norco, CA taking the life of pilot Dave Vopat. The N-9M program proved John Northrop’s belief in an all-wing aircraft design leading to future aircraft with similar characteristics.