In 1938, following the establishment of his own enterprise, the esteemed engineer John Northrop embarked on a long-awaited endeavor. For nearly a decade, he had harbored a vision of crafting a pristine wing design devoid of struts or bracing wire, convinced of its enhanced aerodynamic prowess.

Having navigated through the turbulent waters of the Great Depression, during which he sustained himself by manufacturing conventional aircraft, Northrop found himself in a position of financial stability. This newfound freedom allowed him to revisit his fascination with the flying wing concept, culminating in the birth of the Northrop XB-35.

N1-M

In 1938, Northrop initiated proceedings by sketching a preliminary design of a sleek flying wing devoid of a conventional tail section, incorporating innovative features such as drooped wingtips to enhance directional stability, along with the introduction of novel components termed ‘elevons’, amalgamating the functionalities of both elevators and ailerons.

Subsequently, with the collaboration of Dr. Theodore von Karman, the esteemed Director of the Guggenheim School of Aeronautics, and his aide William Sears, a scaled-down model christened the N1-M, affectionately known as ‘Jeep,’ was meticulously crafted.

Taking flight for the first time in July 1940 under the expert piloting of Vance Breese, the N1-M swiftly proved to be an invaluable asset, providing a wealth of crucial data. Constructed from welded steel tubing and wood, its adaptable framework facilitated swift modifications to its dimensions, enabling Northrop to expedite testing procedures with remarkable efficiency.

200 Spins

Soon Breese and Moye W. Stephens, who would ultimately pilot the N1-M through over 200 test flights, enthusiastically extolled the virtues of the flying wing, marveling at its remarkable acceleration attributable to the absence of fins, empennage, and fuselage sections.

By the conclusion of assessments in 1941, the United States Army signaled keen interest in the innovative design. General Henry H Arnold approached Northrop with a proposition: to adapt the aircraft into a long-range heavy bomber capable of conducting intercontinental bombing raids on Nazi Germany.

Northrop, cognizant of the exorbitant costs involved, welcomed the Army’s involvement and their deep pockets. Thus, in January 1942, Airplane Specification NS-9A was issued, mandating the development of two XB-35 prototypes.

N-9M-1 and N-9M-2

Expanding the wing area from 27.8 square meters to 45.5 square meters, a significantly larger one-third scale model of the N1-M was subsequently constructed to provide a more precise assessment of the flying wing’s characteristics.

This second rendition, designated as the N-9M-1, took its inaugural flight on December 27th, 1942, propelled by two 193-kilowatt Menasco-C6S-4 engines. It was anticipated to possess an endurance of 32 hours and a maximum altitude capability of 21,500 feet.

Crafted from a blend of wood and steel, it boasted a notably compact cockpit, densely packed with instrumentation, and equipped with a fixed seat and rudder pedals.

However, tragedy struck after a mere 22.5 hours of flight time when the N-9M-1 met its demise on May 19th, 1943, claiming the life of test pilot Max Constant. He succumbed to overwhelming aerodynamic forces from the rear, rendering him incapacitated within the cockpit, unable to reach the controls.

Incorporating a bubble canopy for enhanced visibility and a one-shot hydraulic boost mechanism to rapidly push the controls forward during emergencies, the N-9M-2 showcased superior resilience compared to its precursor, completing its maiden flight on June 24th, 1943.

Throughout the initial phase of testing, concluding in April 1944, engineers discovered that the drag experienced by the projected XB-35 at cruising speeds would exceed initial estimations from wind tunnel tests by 7% to 12%.

Nonetheless, the outcomes remained promising, and by June 1944, the confidence was such that the N-9M-2 was utilized as a training platform for USAF pilots.

By October 1944, evaluations were concluded after accumulating a total flight duration of 50 hours, while efforts continued on another variant, the two-seater N-9MB. However, the pressing demand for the P-61 Black Widow necessitated postponing the development cycle for the XB-35 until after the conclusion of the Second World War.

The Flying Wing

The XB-35 emerged as a marvel of engineering, boasting a seamless all-wing design capable of housing a crew complement of nine. Its dimensions stood at an impressive 16.3 meters in length and 6.29 meters in height, with an empty weight tipping the scales at 43,245 kilograms, soaring to a maximum weight of 102,170 kilograms.

Dominating the skies with its expansive and aerodynamically streamlined wing spanning 52.5 meters, encompassing a vast area of 371 square meters, the aircraft commanded precision control through a sophisticated interplay of elevons, trim flaps, and rudders. Initially propelled by Hamilton-Standard contra-rotating propellers driven by four Pratt & Whitney Wasp Major engines, each enhanced with single-stage General Electric turbosuperchargers.

In a later evolutionary leap, the XB-35 underwent a transformative upgrade, adopting single-rotation propellers and bidding farewell to its piston engines, which were supplanted by the thrust of General Electric TG-180 turbojets. This technological leap catapulted its performance to unprecedented heights, achieving a staggering top speed of 391 miles per hour, along with a formidable combat radius extending over 8,150 miles and a service ceiling reaching 39,700 feet.

Armed to the teeth, the XB-35 bristled with offensive capabilities, poised to unleash its payload of a 4,500-kilogram bomb load, complemented by seven powered turrets outfitted with 20 mm cannons. Notably absent was any provision for defensive armament, a testament to the aircraft’s anticipated reliance on its agility to outmaneuver potential interceptors.

Stealing the spotlight on May 16th, 1946, the inaugural XB-35, No.1, graced the Muroc Dry Lake for routine taxi tests, achieving notable speeds of 115 miles per hour, marking yet another milestone in the annals of aviation history.

Less Fanfare

On June 25th, 1946, the inaugural flight took place rather discreetly, owing to a company-wide decree aimed at managing the crowd, which restricted the number of onlookers permitted to witness the event. This directive was adhered to even by the company’s director, John Northrop, who remained at his desk. The following day, June 26th, 1947, saw the arrival of the No.2 XB-35, albeit with significantly less pomp and circumstance.

The XB-35 marked one of the pioneering aircraft evaluated utilizing television cameras, strategically positioned to capture flight instrumentation panels, transmitting live images to a P-61 chase plane.

Despite a few setbacks related to the propellers, the initial evaluations showed promise, prompting the Air Force to commission six production units designated YB-35, boasting enhanced range and payload capacity.

However, the XB-35 program soon faced jeopardy due to widespread speculation that the Convair XB-36 was poised to clinch the Air Force’s competition for a new piston-engined strategic bomber.

To salvage the project’s prospects and maintain its position at the forefront of aviation, Northrop proposed converting two of the YB-35s into turbojet-powered YB-49s.

The public debut of the first YB-49 on September 29th, 1947, followed by its inaugural flight on October 21st, 1947, encountered only minor setbacks. In contrast, the XB-35 encountered escalating hurdles, primarily attributed to issues with its counter-rotating propellers, stemming from gearbox and propeller governor malfunctions.

Tragedy

After assessing the situation, contractors unanimously concurred that expediting the completion of the XB-35 took precedence over any marginal drawbacks posed by the current propeller system. Consequently, a decision was reached to downplay these concerns, albeit not entirely disregarding them. As part of the solution, the two XB-35s underwent a retrofitting process, receiving a brand-new set of four-bladed, single rotational propellers with significantly increased diameters.

With the XB-35s undergoing refurbishment, attention naturally pivoted towards the YB-49, which initially boasted promising progress in its developmental phase, only to be overshadowed by an impending tragedy.

On the fateful day of June 5th, 1948, disaster struck as the No.2 YB-49, shedding its two outer wing sections, crashed over the Antelope Valley test range, resulting in the tragic loss of all five crew members. Despite this catastrophic event, the unwavering confidence of the US Army in both aircraft remained steadfast. Merely five days after the incident, they announced an order for 30 YB-49s, demonstrating their continued faith in the program’s potential.

Downfall

However, the US Army’s acquisition of YB-49s garnered significant attention, marking the apex of the program before its rapid decline ensued.

The initial setback arose with the XB-35 initiative, which encountered insurmountable challenges. Chief among these was the persistent issue with its single-rotation propellers, resulting in recurrent vibrations and metal fatigue that compromised the integrity of the engine cooling fans.

Compounded by unreliable engines, an overly intricate exhaust mechanism, and persistent maintenance hurdles, doubts emerged regarding the XB-35’s viability as a long-range bomber.

Similarly afflicted was the YB-49, notorious for its pronounced instability and challenging flight characteristics, leading to a redirection of funds towards the more promising Convair B-36/RB-36 program, necessitating an additional $300 million investment.

Despite setbacks, Northrop maintained communication with the USAF, buoyed by assurances of a temporary hiatus, evidenced by their acceptance of modified XB-35 airframe proposals.

Hope saw a resurgence following the YB-49’s record-breaking long-distance flight in February 1949, covering 3,630 kilometers in 4 hours and 25 minutes at a speed of 822 kilometers per hour. As desperation mounted in later years, Northrop submitted various flying wing variants to the USAF, including a turboprop-powered bomber, an escort fighter, and notably, the EB-35B, intended as a test platform for the advanced XT-37T Turbodyne gas turbine engine.

On January 11, 1949, the Air Material Command officially terminated the YB-49 program, with the exception of the YRB-49A reconnaissance variant, which saw its demise by the summer of that year and eventual dismantling in 1953.

Subsequently, in February, both XB-35s were slated for scrappage, and from March 15, 1950, all YB-49s met the same fate, marking the end of an ambitious yet troubled chapter in aviation history.

Northrop YRB-49A

Following the termination of the B-49 initiative, the Air Force diverted funds towards repurposing the tenth YB-35 (42-102376) into a prototype for an unarmed, long-range photographic reconnaissance aircraft. This revamped rendition, dubbed the YRB-49A, and internally referenced as Model NS-41 by the company, underwent significant alterations.

The aircraft was outfitted with four 5000 lb.s.t. Allison J35-A-19 engines, with a pair affixed to each wing, supplemented by two additional J35 engines housed in pods beneath the wing’s leading edge. This engine configuration not only facilitated augmented fuel storage within the wings but also addressed yaw-axis stability concerns previously encountered during YB-49A testing.

Furthermore, the engine pylons were ingeniously repurposed as vertical stabilizers, serving a dual function in enhancing stability.

The crew complement for the aircraft comprised six members: a pilot, co-pilot, flight engineer, photo navigator, radar navigator, and photo technician. Critical photographic equipment for reconnaissance missions was housed in the tail cone bay, situated beneath the aircraft’s center section.

Internally, the reconnaissance variant was designated N-37, while N-38 was earmarked for the proposed modifications of the YB-49s, incorporating equipment initially slated for the RB-49.

Northrop secured a letter contract on June 12, 1948, for preliminary engineering efforts, subsequently formalized on August 12, 1948. This contract, potentially culminating in a production order for 30 aircraft, bore serial numbers ranging from 49-200 to 49-229.

Would fall behind in speed compared to the B-47.

Recognizing the potential synergies between Northrop’s engineering prowess and Convair’s expertise in large-scale aircraft manufacturing, the Air Force’s contract stipulated that only one of these aircraft would be produced by Northrop, while the remaining 29 would be assembled by Convair at its government-leased facility in Fort Worth, Texas. This strategic decision aimed to capitalize on the respective strengths of the two companies in crafting and delivering this advanced aircraft.

However, the performance of the proposed six-jet RB-49A fell short in comparison to the B-47, prompting the Air Force Board to recommend the immediate termination of the RB-49A project. This suggestion was formally adopted in late December of 1948, leading to the reallocation of funds initially designated for the RB-49A towards additional B-36 aircraft.

Official confirmation of the cancellation of the RB-49A project came in mid-January of 1949, with Northrop instructed to cease all related activities, save for the completion and testing of a single YRB-49A, designated for a proof-of-concept research and development initiative.

The YRB-49A undertook its maiden test flight on May 4, 1950, traversing from Hawthorne to Edwards Air Force Base. Subsequent testing of the aircraft commenced at Edwards AFB over a duration.

However, during its tenth test flight on August 10, 1950, a critical incident unfolded as the cockpit canopy detached mid-flight, resulting in the pilot losing their oxygen mask and sustaining minor injuries. Fortunately, the flight engineer swiftly administered emergency oxygen, facilitating a safe landing of the aircraft.

Left Outdoors

The YRB-49A underwent a brief testing period, consisting of only 13 flights, before being mothballed towards the end of 1950. In early 1952, the aircraft was transported to Northrop’s facility at Ontario International Airport in California with the intention of installing a stabilizing device.

However, funding for the YRB-49A project had been halted by the Air Force by this time, leading to the aircraft being left exposed to the elements for an extended period in outdoor storage. Eventually, in November 1953, the Air Force made the decision to scrap the aircraft.

The designation N-40 was assigned to an RB-49 that had been earmarked for conversion into a prototype of the production B-49 bomber variant.

Multiple engine configurations were considered for the N-40/production B-49, including eight J47s (six integrated into the wing’s trailing edge between the fins and two housed in separate pods under the wings), six J40s, a combination of two T37s with either 2 or 4 J40s, and six J48s (Rolls-Royce Tays produced under license by Pratt & Whitney). Designations N-46 and N-47 were allocated to advanced design studies for the RB-49, which incorporated T37 turboprops.

N-50 was designated for Northrop’s proposed modifications to enhance the stability of the remaining YB-49 prototype.

However, this plan never materialized as the aircraft, bearing the serial number 42-102367, was destroyed in a taxiing mishap. N-52 was the internal designation employed by Northrop for the intended Air Force testing phase involving the YRB-49A, a phase that ultimately failed to materialize.