Modern design in many things often finds itself borrowing on old, tried, and true concepts. It’s no surprise either. After all, throughout history we find many instances where modern technology, strategy, design, and concepts can be traced and originated on something that already exists. Imagine, if you will, not reinventing the wheel, but improving it. That is how we observe a breakthrough today. The computer is a fine example of this, going from a system the size of a small building in the 1950s to a small handheld device the size of thousands of the same capacity in 2010. But there is another place that is all too obvious: aviation.

From the beginning, Wilbur and Orville Wright had a vision that launched man into the heavens above. Shortly after their successful flight at Kitty Hawk in 1903, interest in the airplane had expanded far beyond just a select few. While the United States Signal Corps had taken a limited interest in the new technological marvel, it still wasn’t convinced of its long-lasting capabilities. The early airplane instead was kept in a reconnaissance capacity for the Signal Corps up until the late stages of World War I. But as man is known to do, it sought to improve and aim higher and more efficiently in its zeal for aviation supremacy.

In modern aviation, we consider some of the most iconic designs and aircraft in our skies as creations such as the F-22 Raptor, the F-16 Viper, and the B-52 Stratofortress (at least, for us in the United States). Elsewhere, you see the MiG-29 Fulcrum, the Su-35 Super Flanker, and the Eurofighter Typhoon. Perhaps the most interesting in design, however, belongs to the B-2 Spirit bomber, a design that is certainly distinguishable. It’s flying-wing design, low radar cross-section, and quiet footprint are noteworthy characteristics that make this aircraft one of the most unique. But how unique is it? It may surprise many to know that such a design is over one-hundred years old. How did this amazing man-made marvel change from its incarnation in 1910 to now? Let’s continue…

By 1934, Northrop was aware of the Horten’s exploits in Germany.  His arguably partial success with the X-216H had enabled him to be in a position of expertise.  Northrop’s end goal was for a true flying-wing, and the transition from the X-216H to the N-1M (and later the N-9) were the natural progressions from concept to functionality.  The initial N-1 was a conceptual flying-wing bomber that was supposed to meet the requirements for a new medium-range bomber, but limitations and modifications needed for design resulted in a lapse of time to fulfil this order.[13]

Despite minor stability issues, the craft was largely kept on the ground by poor relationships between size, weight, and power.  Certain maneuvers caused instability in an otherwise stable and controllable design.  The bulk of the issues, however, came from the power plant on the aircraft.  The Lycoming O-145 engines put out a total of 130 horsepower for an aircraft that weighed just shy of 4,000 lbs.[14]  Northrop eventually upgraded these to Franklin 6AC engines that produced approximately 235 horsepower.[15]  By the time the U.S. Army Air Force awarded the contract for a prototype medium strategic bomber with Northrop just a month ahead of the Pearl Harbor Attacks, the N-1M had made 28 successful flights.  These flights provided valuable information for what would become the YB-35.[16]

With a contract award in hand, Jack Northrop and his fledgling company set out on a mission that had already been 12 years in the making.  What he did not know, was that it would take at least another 40 years before his dream would be a permanent stay in the skies.  However, the rest of these 40 years began with only shades of difference from its eventuality.

The steppingstone between the mockup flying wings and their eventual successors came in late 1941 when the U.S. Army Air Force awarded a contract to Northrop for what would become the XB-35.  Northrop had already been collecting valuable data on the flying wings with the N-1M, but the mission set for the XB-35 would prove to be far too different to rely on that data alone.  A 3:1 scale mockup of the 60-foot wing-span aircraft was created to help collate and confirm data.  This model was the Northrop N-9M.[17]

Unlike its predecessor, the N-9 used a much more powerful powerplant.  Northrop sourced Menasco Buccaneer engines, capable of outputting a total of 550 horsepower, over four times the power of the original powerplant.  However, the aircraft also weighed three times it’s original weight with a gross weight approaching 13,000 lbs.  In general, between the four aircraft produced, the approximately 600 horsepower powerplants pushed the aircraft to a speed of around 250 miles per hour. [18]  While the aircraft was not exactly a speed demon, its intention was more for research in stability, control, maneuverability, and feasibility.  The initial N-9 agreement was for three test aircraft, with a fourth included after one of the models was lost in a crash.  Models 1, 2, A, and B were the four aircraft produced.[19]  The N-9M1 aircraft crashed near Edwards Air Force Base in California in May of 1943.  The aircraft had only been flying for six months at the time of the crash.  Models 2 and A were already planned, but model B was added to that request.[20]

There were a few design differences in addition to the technological changes between the N-1M and the N-9.  Chief among these was the wing slope, tips, and the profile of the engine intakes.  The angle of the wing was much more dramatic, and the profile of the canopy was also better integrated.  Lastly, the rear of the aircraft was made somewhat concave, creating more of a flying-wing than a delta.  From here, more similarities existed rather than differences.  Both aircraft utilized rear-facing, twin-prop engines and used wood construct with a metal base.  Demonstration of the aircraft proved useful and successful enough that Northrop was able to move on to the full-scale model, the real-deal, and what would eventually become a mainstay in United States Strategic Air Command’s arsenal.

The B-29 nor the B-32 (the Consolidated strategic aircraft that served in a similar capacity to the B-29) were the only strategic bomber concepts on the market.  Lockheed and Douglas were also in the mix with their own unique submissions.  Lockheed bowed out, but later returned with their P-80 Shooting Star; the first U.S. Army Air Force (USAAF) jet-powered aircraft.  All these concepts had one design concept in common, in that they stayed with the normal design schematic of larger aircraft.  Jack Northrop and his team, however, were testing something that was still wildly exotic, and were doing so with quite a heap of success.  Despite the success, the war had thankfully ended, and many were questioning the state of the defense budget.  The biggest monkey-wrenches in a potential cut were the dawn of the Atomic Age and the new established need for a global presence and containment.  These worked in the favor of creative minds such as Northrop.

The suspense must have been palpable in late June of 1946 for a team of engineers, a flight crew, and a team of designers in Hawthorne, California.  For some it was a culmination of research that had begun with the X-216H in 1929, for others it began with the USAAC order in 1941.  For Jack Northrop, however, the moment of truth was close at hand.  The results of the testing from the N-9M were about to come to a head.  So ready, was this team, that it had installed engines in the aircraft that had not even been tested yet or given any kind of reliability check or quality assurance pass.[28]  Nonetheless, 25 June 1946 was a day of celebration as Test Pilot Max R. Stanley along with flight engineers Dale Schroeder and Orva H Douglas, Jr. conducted the first flight of the XB-35 (42-13603).  The 55-minute flight took the aircraft from Hawthorne to Muroc Army Air Field, present day Edwards Air Force Base, California.[29]

The flight was described as “smooth” despite the untested engines and poor stress test results that followed the initial flight.[30]  Aside from the success, the XB-35’s performance specifications were rather unremarkable having just met the requirements outlined by the USAAC.  What it exceeded, however, was efficiency, payload, and defenses.  Its speed was overshadowed by the concept of jet aircraft, and despite its maximum speed of 390 miles per hour with a 240 miles per hour cruising speed, many officials in the USAAF believed that the aircrafts engines made it obsolete.[31]  The USAAF had already committed to multiple testbed prototypes.  Coupled with the unique and new technology deployed on the aircraft, the USAAF and subsequent U.S. Air Force (USAF) were not ready to call it quits on the program.  Jack Northrop and his team certainly were not either.

The design of the YB-35 was the 1:1 scale that the N-9M was based on.  Internally referred to as the N-9S, the YB-35 had a 172-foot wingspan and was a true flying-wing.  It had an armor compliment of 20 M3 Browning .50 caliber machine guns that were in six separate pods around the aircraft, plus a tail gunner in the stinger.  It was designed to have a payload of around 50,000 lbs.; however, the original design would not have accommodated the new nuclear bombs such as Fat Man.  The aircraft was to have a crew of nine, with the cockpit being situated off-center of the nose.  Each propeller was an eight-blade contra-rotating propeller which was designed to maximize efficiency.[32]

The YB-35’s persisted in the skies even after the B-36 made it’s inaugural flight on 8 August 1946.  The B-36 was the selected bomber for the USAAF.  Issues with the propellers, proprietary tooling, and the lack of jet engines were cited as the reason for the B-36 selection.[33]  While the initial B-36 design was aided by propellers, the B-36D had included four jet engines to reconcile issues with its size and weight.  Perhaps, luckily, the YB-35’s persisting in the skies quickly were adapted to the new jet standard with relatively little pain.  The B-36 program on the other hand resulted in one of the most significant blunders in USAAF history and were the chief headache for the newly formed USAF.  The fallout resulted in significant friction in the armed forces, particularly between the Navy and the Air Force, as the former was attempting to utilize funding to fleets that could deploy strategic bombers, rather than utilizing an around the world approach.[34]

While the USAF and Navy argued over whether defense budgeting favored supercarriers or superbombers, Northrop and his team were setting their sights on something a bit more reasonable.  The future was clear, and that future was for jet engines to reign supreme in the skies.  Three of these aircraft were to be converted for the experiment, although all the produced YB-35s were slated for the conversion.  This isn’t to say that the aircraft didn’t have its flaws.  Pressure was beginning to mount for both the B-35 and B-36 programs.  Excessive budget overruns were creating a tense situation, so much so that the House Armed Services Commission launched investigations into both programs.[35]  However, it would be a few years before these cuts would hit the Northrop team.

It would not be fair to talk about the B-36 in passing without examining it at least briefly.

The B-36 was, for all intents and purposes, a monster of a machine.  It had a 230-foot wingspan and was the largest propeller driven aircraft to have ever existed.  This was only temporary, as jet engines eventually were retroactively fitted on older models.  The aircraft boasted a payload of up to 86,000 lbs and carry atomic payloads standard.  It was the first bomber to be able to do so.  Unlike its competitor, it featured only a single tail gun that was operated remotely and fitted with two M24A1 autocannon.  The aircraft was roughly 150 percent larger than the B-29 Super Fortress and weighed over three times as much.[36]

Setbacks in development, problems with upkeep, operations costs, general repairs, along with significant problems in the research and development process resulted in the programs high-profile controversy.  So controversial was the program that it acquired the name of “the billion-dollar blunder.”[37]  The chief competitor in defense department budget was the Navy, who was attempting to fund its next generation of supercarrier.  When the newly created Department of Defense sided with the newly founded Air Force, resulted in a massive uproar, often referred to as the 1949 Revolt of Admirals.[38]

Rushing.  The feeling of designers keeping up with the world around them.  Rapid.  The pace of the advancement in technology the world was beginning to see.  Containment.  The prevailing need as the Red Scare gripped the world and the Iron Curtain descended over Eastern Europe.

The precariousness of daily life after World War II was sensitive and uncertain enough.  The world was tired after two wars had gripped her, and her citizenry was just as tired.  However, a new sense of unease had settled in as the free West laid eyes on a new enemy: communism.  The ideology that had taken over Russia in World War I saw a grand opportunity to spread during World War II to other Eastern European nations.  Now, it threatened to overtake more.  This is what allowed programs such as the B-36 and the YB-35 to persist.

On the other hand, technology was advancing rapidly, and the roughly perfected jet-engine had established itself as the engine of the future.  While Convair worked to fit new B-36D’s with jet-engines, and eventually retrofit back to the B-36B,[39] Northrop’s unselected option remained potentially viable with the promise of fitting with jet engines.  Feeling pressure exerted by the B-36 program and the setbacks from the YB-35, Northrop set out to cut corners in cost by converting existing YB-35’s with jet engines while improving avionics.  The result was the YB-49.[40]

Of the YB-35’s produced, only three were fully converted to the YB-49 prototypes.  Most of the flight testing and operations were conducted from Muroc (Edwards) Air Force Base over the course of four years.  There were some design, performance, and armament changes in the YB-49 from the YB-35.  These changes were implemented in large part due to cost overrun or performance modification to reconcile problems in the YB-35’s original testing phase.

The initial YB-49’s utilized eight Allison J35-A-15 turbojet engines that produced about 4,000 lbs. of thrust each.  This gave the YB-49 a significant increase in speed relatively speaking over both the YB-35 and B-36, topping out just shy of 500 miles per hour.  However, it’s payload was cut to a mere fraction of its previous iteration at under 20,000 lbs.  In addition, the twenty Browning .50 caliber machine guns were reduced to four in the stinger alone.  Because of the reduction of guns, this meant the number of crew was also reduced from nine to six.[41] Despite all of this, there was one significant factor to be considered with the YB-49 that got many in the Air Force interested in ongoing testing and research.  The YB-49 exhibited a significantly reduced radar-cross section (RCS) from previous designs.[42]

The operational history of the YB-49, sadly, was not one of grand success.  Two of the prototypes were lost, and the last one was scrapped.  The Air Force had sought a new mission for the YB-49 due to it’s RCS and design specifications: reconnaissance.  The current recon mission was being carried out by a handful of converted B-29’s and newly retrofitted RB-47’s.  In 1949, the USAF formally submitted a request to order the YB-49 for its strategic reconnaissance mission with the designation RB-49.  Northrop modified the YB-49 for the reconnaissance mission and began testing under the internal control numbers N-38 and N-39, and USAF designation YRB-49.  The YRB-49 utilized six engines instead of eight.  Four of the Allison J35-A-19’s were mounted in the wing itself, while the other two were mounted on pylons under the wing.[43]

The project, however, was eventually cancelled abruptly in 1951.  The USAF opted to use the converted RB-47’s and convert the RB-57 for the reconnaissance mission instead.  They would not revisit a dedicated reconnaissance platform until Lockheed’s CL-282 (1953) proposal that eventually produced the U-2 (1955).  There are several different reasons cited for the cancellation of the program.  The reallocation of focus on the bomber need had since been filled by the B-36 (albeit poorly), B-47, and Boeing’s Model 464 (eventually becoming the B-52).  Northrop had been spreading itself thin on other experimental aviation research as well, including engines and avionics.  Cost overruns within the YRB-49 program, coupled with overruns in the B-36 program may have also led lobbyists in Washington and officials in the Department of Defense to make some budgeting cutting decisions.[44]  Regardless of the reason, the program was terminated in 1951, and the last aircraft was scrapped in 1953.[45]