airfoil technology
piston aero engines
jet engines
slotted wings and wing additions
development of swept wings
Horten flying wings
Northrop flying wing
forward-swept wings
delta wings
variable-sweep wings
supercritical airfoil
the monoplane
variable pitch propellers
metal skinned aircraft
retractable landing gear
NACA engine cowling
stealth technology
aviation fuel
aerial refuelling
aircraft noise reduction
V 2 missile technology
early X Planes
X15 and hypersonics
Nord Gerfault X-plane
lifting bodies
VTOL and STOL Aircraft
Soviet composite Aircraft
technology of landing
technology of navigation
development of autopilots
aircraft simulators
advanced aircraft materials
Unmanned Aerial Vehicles
Nuclear powered aircraft
the area rule
air defence

The Northrop Flying Wing and the B2 bomber

A design as aeronautically clean as the Flying Wing has a big advantage over conventional aircraft design. This advantage is that drag has been reduced to a minimum. And as a result of this minimum drag, the performance of the Flying Wing is unequalled in speed, range and operating economy.

For many years airplane designers have realized that by reducing drag -- the drag caused by the shape or form of an aircraft -- its performance could be greatly increased. Early steps in this direction were changes from biplane to monoplane design; the elimination of external wing struts and flying wires; and the incorporation of retractable landing gears. However, in spite of all these advancements, the average conventional airplane of today still has two to four times the drag of a flying wing. So in order to reduce drag to its absolute minimum, aircraft designers took the drastic step of eliminating the fuselage and tail and putting the pilot, the power plant and payload in the wing envelope.

The chief exponent of Flying Wing design in the United States was John K. Northrop. John Northrop was born in Newark, New Jersey in 1895. When he was nine years old his family moved to Santa Barbara, California. His great interest in mechanics curtailed his formal education, and, after brief periods as garage mechanic, carpenter and draftsman, he went to work in 1916 for the Loughead Brothers, who were then engaged in building twin-engine flying boats in Santa Barbara. Except for a stint with the Army Signal Corps during World War I, Northrop stayed with the Lougheads until 1923. In that year, he joined the Douglas Aircraft Company, which was then preparing the famous Around-the-World Cruisers. He stayed for four years working as draftsman, designer and project engineer on many early Douglas planes. 

In January, 1927, John Northrop and three other men formed the Lockheed Aircraft Company. It was at this time that he designed the famous Lockheed Vega — a high wing, cantilever monocoque airplane which was far ahead of its time in design. It was widely used by many of the top flyers such as Amelia Earheart, G. Hubert Wilkins, Frank Hawks, and the noted Wiley Post. Many speed records were set by the Lockheed Vega aircraft.

In the summer of 1928, John Northrop began his research of flying wing aircraft. He formed a small engineering group known as the Avion Company. He built and test flew one of the first 2mi-flying wing aircraft in the country. Although it did carry the pilot and engine power plant in the wing, it was not a true flying wing because of its small tail carried on twin booms. This plane made numerous flights in 1929 and 1930 and recorded much valuable research data. Unfortunately, the depression of the early 1930’s caused further research to be abandoned.

As years passed and further advancements were made, John Northrop became recognized as the genius behind the Flying Wing design and the leading exponent of flying wing design in the United States. In Germany the flying-wing-design concept advantages were also shared by Alexander Lippisch and the Horton Brothers and in England by Hill. All were designers, who built and flew successful Flying Wing aircraft. Because it had no fuselage, even the Wright Bi-plane can be considered in this category in spite of its multiplicity of wing struts and wires. The Wrights’s plane carried the power plant and pilot directly on the wing system and was controlled longitudinally by a front elevator which was, in fact, a lifting wing surface.

In 1923 John Northrop became interested in the flying wing design after a discussion with Tony Stadlman, who had worked with Northrop in 1917 at the Lockheed factory, then located in Santa Barbara. Stadlman was plant manager of the Douglas Company in Los Angeles at this time and young Northrop was an engineer. Stadlman believed the ideal aircraft of the future was in the true “flying wing” design. From that day on John Northrop’s goal was to design and perfect the Flying Wing.

During the early stages of design development, Northrop held discussions with the late Dr. Theodore von Karman of the California Institute of Technology. Northrop later hired Karman’s  assistant, Dr. William Sears, to become his Chief Aerodynamicist. Walt Cerny, who came to work for Northrop in 1929, was made assistant Chief of Design. These men had direct supervision of the Flying Wing from its inception. The encouragement and assistance of these men, plus the enthusiastic collaboration of the many Northrop employees, enabled this amazing design to become a reality.

The pressure of designing and building conventional aircraft prevented complete concentration on the solution of the Flying Wing design, and it was not until later that they were able to focus their efforts on Northrop’s dream of a true flying wing.

Northrop’s first semi-flying wing plane was flown in 1928. It did make use of external control surfaces and carried outrigger twin booms -- quite a radical aircraft for its time. The fuselage was completely eliminated, and the pilot was housed in the wing along with the power plant.

The big problem overcome in designing the flying wing revolved around the buried engine concept. The entire engine propeller shaft had to be buried within the wing foil. This increased the problems of cooling the engine and of turning the long drive shaft to the propellers.

The dimensions of the first Northrop semi-flying wing were: It had a wing span of 30 feet, 6 inches, its length was 20 feet, and its overall height was five feet. Wing area was 184 square feet and aspect ratio was 5.12 to 1. Landing gear was of the tricycle type with the main wheels forward and a tread of 9 feet between the main wheels. Power was supplied by a single four-cylinder 90 horsepower Menasco engine for the tractor powered version. This aircraft later was powered by a Cirrus Engine when it was rebuilt as a pusher-design aircraft.

N1M “Jeep”

In July, 1939, John Northrop began engineering tests for a new flying wing design. This design was known as the N1M “Jeep”. The first flight tests were conducted at Muroc Dry Lake in July 1940. Test pilot for the first flight was Vance Breese. Early tests showed the plane to be satisfactory in stability and control. Shortly thereafter, the flight test program was turned over to Mr. Moye W. Stephens, Northrop Test Pilot and Secretary to the Northrop Corporation. During 1940 and 1941, over 200 flights were made in this aircraft to gather further data. Control of the aircraft was achieved through the use of a system of elevons and wing tip rudders. The elevons served in tailless type aircraft both as elevators and ailerons. Rudder action was provided by control surfaces incorporated in the drooping wing tips.

This wing had a wing span of 38 feet and a length of 17 feet, an overall height of 5 feet, a wing area of 300 square feet, and an aspect ratio was 4.75 to 1. It, too, had a tricycle landing gear. It originally carried two four-cylinder Lycoming engines of 65 horsepower each, which were later replaced by two six-cylinder Franklin air-cooled engines of 120 horsepower each. The drooping wing tips of the N1M were later eliminated.

The Ni M “Jeep” was truly the first American flying wing aircraft. Today it resides in the National Air and Space Museum Storage facility at Silver Hill, Maryland, a short distance outside of Washington, D. C. It is hoped that this aircraft is one that will be displayed in the new Air and Space Building when it is completed on the Mall in Washington, D.C.

 XB-35 Flying Wing

The XB-35 was the first in a series of large Flying Wing Bombers. It was a bombardment type aircraft of exceptionally long range and heavy load capacity. Two XB-35 and 13 YB-35’s were initially scheduled to be built under Army contracts. But only six of the big wing bombers were completed and test flown. The XB-35 had a wing span of 172 feet and a wing area of 4,000 square feet. It was capable of operating under overloading conditions at a gross weight of 209,000 pounds or 104.5 tons.

Prior to the XB-35 design, Northrop had flown twelve tailless aircraft designs since the company was founded. Northrop engineers learned much about these experimental models and had made hundreds of additional models for wing tunnel tests. For the first time in the history of military aeronautics, the flying wing contributed many advancements to military design in the bombardment category. Five of the leading advantages were:

1. The low drag, high lift feature of the Flying Wing meant that in practice the XB-35 could transport any weight faster, farther and cheaper than an aircraft of conventional design.

2. The simplicity of construction of the XB-35 Flying Wing presented few structural complications. It cost less to build since it was built as a single unit in which the structure extended through from tip to tip with no added tail or fuselage to build.

3. It had better weight distribution. Compartments along the span could distribute the bomb load and weight more evenly over the wing surface which supported it. This also would have applied to cargo if a cargo version had been built. It eliminates the need for excessive structural weight such as is necessary in conventional bombers where the weight is concentrated in the fuselage and must be distributed over the wing from this point through the use of heavy structural members.

4. For ease in loading and unloading, cargo could be placed in span wise compartments where any part of the plane’s load was easily accessible through its own cargo or bomb bay doors. This provided direct access to all portions of the cargo.

5. The XB-35 for military purposes presented a smaller target while engaged in either offensive or defensive operations. Comparisons between the Flying Wing and conventional aircraft is also illustrated by performance figures obtained from Northrop and backed by many years of research tests in which planes identical in scale to the XB-35 were used. The XB-35 was built to be 20 percent faster than conventional bomber aircraft with identical loads and horsepower. Normal crew for the XB-35 was nine men --a pilot, co-pilot, bombardier, navigator, engineer, radio operator, and three gunners.

Cabin space was available for six more crew members, who could substitute on long-range missions. Folding bunks were built in the XB-35 to accommodate the off-duty crewmen. These fifteen men were housed entirely within the wing foil itself. The XB-35 was built of a new aluminium  developed by the Alcoa Company. Tests showed this material to be considerably stronger than previous metals used. Gasoline was carried in bullet proof, leak proof fuel cells within the wing of the XB-35 and additional range was built in by the addition of additional fuel tanks in the bomb bay and other wing compartment areas. The wing section of the XB-35 was 37-1/2 feet long at the  centre, tapering to slightly more than nine feet at the wing tips. It swept back from centre to tips making the overall length of the ship slightly more than 53 feet. The XB-35 stood over 20 feet tall when at rest on its tricycle landing gear. It was equipped with 5’6” dual wheels on the main gear and a 4’8” wheel on the nose gear. 

The XB-35 received its initial start from the Army Air Corps in September, 1941, following a visit by Assistant Secretary of War Robert Leavitt, General H. H. Arnold, and Major General Oliver P. Echols. At this time, Northrop submitted a preliminary design for the XB-35 to Wright Field. Army officials were more than satisfied because they awarded a contract for the altitude performance with a pressurized cabin for the crew and a more than adequate bomb load. There would not have been an XB-35 Flying Wing Bomber had it not been for the enthusiasm and foresightedness of men like John Northrop, General Arnold, General Echols, and Mr. Leavitt.

In November, 1941, two XB-35 prototypes were ordered by the Army Air Force. Preliminary design work began on the XB-35 early in 1942, and on July 5th of that year the mock-up Board from Wright Field inspected a full size wood mock-up of the centre section and a portion of the left wing. Official approval was given. Northrop built a new bomber plant at the end of the company’s grounds in Hawthorne, California. This plant was completed in January, 1943 and fabrication of the parts for the first XB35 were begun. The complexities of design in building the B-35 represented an operation of major size. The Martin Company played a very important role by providing wind tunnel and other research data for the XB-35 design. To provide flight test data, Northrop built four, sixty foot wing span N9M Flying Wings. While the XB-35 was taking shape in the Hawthorne factory, thousands of test flights were run on the N9Ms to gather data which could be worked into the XB-35 design. This time-saving device enabled Northrop engineers to cut development time from the XB-35. Over the next three years flight tests were conducted at Muroc Army Air Base to gather data while the XB- 35 was taking shape.

 A X8-35 is shown in flight over Muroc Dry Lake. Eight four-bladed counter rotation propellers drove the Flying Wing through the  air. This view clearly shows the turret blisters on the upper portion of the wing envelope.

 The XB-35 used elevons which were installed on the trailing edges with landing flaps, trim flaps and rudders. The elevon was a Northrop invention in which the function of both elevators and ailerons were combined. Further control was achieved by wing slots. The XB-35 was first flight tested during the summer of 1946 by Northrop’s Chief Pilot, Max Stanley. One YB-35 was slated to be turned over the the Navy and was to be designated XB2T-1; however, this did not take place. The Navy was to have flown and tested the aircraft for research purposes, but this project was cancelled.

After the prototype XB-35 models were built at the Hawthorne plant, a war time plan was begun to build 200 B-35 Flying Wing bombers by Martin Aircraft Corporation at Omaha, Nebraska. Martin had previously built B-29 bombers, and it was expected that these would be phased out - in favour  of the B-35 Flying Wing Bombers. This program was dropped, however, with the conclusion of World War II. The first XB-35 flew on June 25, 1946. The power plants of the XB-35 were Pratt-Whitney “Wasp Major” engines. It had two B-4360-17 and two R-4360-21 engines of 3,000 horsepower each with double turbo super chargers and eight coaxial counter rotating - four bladed Hamilton Standard pusher propellers. Tests were also run on three-bladed propellers, but the four- bladed models proved to be the most efficient. The aircraft was designed so that other types of engines could be adapted as they were made available.

 The XB-35 was to have carried twenty 50 calibre machine guns, but these were not installed on the number one prototype XB-35. Seven remote-control gun turrets were aimed from central firing sighting stations behind the pilot and on top of the cone protruding from the trailing edge. Four gun turrets were fitted above and below the centre section. Two gun turrets were visible outboard of the engines -- one on top and one below. Four guns were to have been placed in the tail cone. The first two XB-35 and sole YB-35 Flying Wings had “Wasp Major” engines. But on June 1, 1945, orders were issued to have the next two finished with Allison J-35-A-5 jet engines. These models were known as YB-49 jet Flying Wing Bombers. On June 25, 1945, American Aviation took a bold step into the future. On this date the world’s first all Flying Wing Bomber took to the air from Northrop Field at Hawthorne, California. The crew for this first flight were pilot, Max Stanley and Dale Schroeder, flight engineer.

 Following the flight of the first XB-35, (SIN 42-13603), a second prototype XB-35 first flew in November of 1946. The second prototype XB-35, (S/N 42-38323) soon joined her sister ship on the ramp at Muroc Army Air Base. When the XB-35 was completed and had made its maiden flight, further tests were conducted to prove the feasibility of the design. The two Pratt-Whitney R-4360-21  Wasp Major engines drove the inboard contra-rotating propellers and the two R-4360-17’s turned the outer pair of propellers. Each engine developed 3,000 horsepower. The metal housing over the propeller shafts offered enough area to counter-act any yawing tendency of the Flying Wing design, and counter rotating propellers gave additional stability by eliminating torque problems. Cooling air for the radial engines were ducted from openings in the leading edge of the wing. The XB-35 had a maximum speed of 395 miles per hour and a cruising speed of 183 miles per hour.

 this is a rare photo of nine Northrop Flying Wing Bombers. Many people do not realize that more than one or two prototypes were built of this design. Here, for the first time, is actual proof of their existence. Two of the big wing bombers are undergoing modifications from  XB-35’s to Flying Wing B-49 1t Bombers. The entire project was later cancelled by the Air Force. 

YB-49 and YRB-49A

With the introduction of the YB-49 to flight status in the fall of 1947, it was anticipated that this model would prove to be the most successful flying wing aircraft. A contract ordering the conversion of two YB-35 Flying Wings was issued on June 1, 1945. This specification called for the installation of eight Allison J-35-A-5 turbo jet engines of 4,000 pounds thrust each.  The YB-49 Flying Wing weighted 88,100 pounds when it was rolled out of the factory. The normal loaded weight was 205,000 pounds. This could be boosted to 213,000 pounds if necessary. The first flight was made on the number one prototype YB-49 on October 1, 1947. This aircraft, S/N 42-102367, was successfully flown from Hawthorne, California to Muroc Air Force Base by Northrop’s Chief Test Pilot, Max Stanley. Subsequent test flights pushed the plane to a top speed of 520 miles per hour and placed the ceiling surface at 42,000 feet. It held fuel capacity of 17,545 gallons and had a range of 4,450 miles. The YB-49 Flying Wing jet bomber was capable of carrying over 36,760 pounds of bombs for a distance of 1,150 miles. A normal 10,000 pound load could be carried for an estimated 4,000 miles on 6,700 gallons of fuel. This was less than half the range of the B-35. This was due to the great quantity of fuel required by the turbo jet engines; however, a 100 mile increase in speed was gained in the YB-49.

Over twenty months of research and flight testing was conducted on the two YB-49 prototypes at Muroc Air Field. During this time, payload tests and endurance records were broken. Contracts were placed for thirty RB-49’s and for converting the remaining ten B-35 airframes to YRB-49A strategic reconnaissance type aircraft. During two years of flight testing, stability problems encountered in the YB-49 design had not been overcome and further tests were planned. A new autopilot was to be designed and built into the aircraft. Before this could be done, the first prototype crashed:

 On the morning of June 5, 1947, Captain Glenn Edwards, a test pilot at Muroc Air Force Base, was command pilot on the number one prototype YB-49. The aircraft had several stability tests which had to be completed before this aircraft was placed in quantity production. Scheduled stability tests were conducted this day at 40,000 feet at a location just north of Muroc Dry Lake. Captain Edwards radioed to base after his tests were completed; they were dropping down to 15,000 feet. The pilot was not heard from again. Witnesses said they saw it tumbling down out of control just north of Highway 58 and crash. Captain Edwards and the entire crew were killed. What exactly happened is not known. The clean all wing design of the YB-49 enabled the aircraft to reach very high speeds. In descending from high altitudes, the YB-49 could easily surpass “red line” (not to exceed) air speed. It is assumed that Captain Edwards was attempting to investigate the stall characteristics of the aircraft, and the “not to exceed” limits of the aircraft were exceeded while descending from 40,000 feet. In exceeding these limits, the outer wing panels were shed and the aircraft tumbled in three pieces to the ground.

 The second prototype YB-49, (S/N 42-1 02368), was burned and destroyed during a ground taxiing accident at Edwards Air Force Base. The YB-49 crash site can still be seen today. Located ten miles north of the city of Mojave and just east of Highway 14, the scorched earth and a few bits of plastic and metal are all that remain as a monument to this amazing design. This crash rang the death knell for the YB-49 Flying Wing program. Muroc Air Base was later named in honour of Captain Glenn Edwards. Today it is known as Edwards Air Force Base, Flight Test Centre of the United States Air Force. Only two YB-49’s were completed and test flown. It had a load factor of two and a top speed of 520 miles per hour and a service ceiling of 42,000 feet. The YB-49 had eight Allison J-35-A-5 turbo jet engines. These were located in banks of four at either side of the wing, and the only protuberances were the exhaust along the trailing edge. Air intakes were mounted in the leading edge of the wing. All gun turrets, except for the tail cone guns, were eliminated. Four vertical
stabilizing fins were fitted. The regular crew of seven were housed entirely within the seven foot thick wing centre section. The pilot was located in a plastic bubble canopy near the leading edge for excellent visibility. For long flights provision was made for an off-duty crew of six members who had quarters in the tail cone just aft of the flight section. One YB-49 averaged 511 miles per hour during a 2,258 mile flight from Muroc, California to Washington, D. C. Flights of over nine hours duration had been recorded.

These performances give support to the flying wing design. At its time it was one of the world’s longest ranging jet aircraft. Flying scenes of the YB-49 aircraft were featured in a Hollywood film based upon H. G. Wells’ “War of the Worlds”. If one is privileged in viewing this on a late show on television, you will see an extraordinary art form of flying, banking, rolling and turning as graceful as any plane that flew. Watching the Flying Wing fly and perform in colour is an experience not easily forgotten. This author had the privilege of viewing the YB-49 flying at March Field near Riverside, California in May, 1947. Its grace and beauty in the air will always be a sight to be remembered, but what impressed most was its ability to turn inside the top Air Force Fighter of the day -- the P-80 “Shooting Star”.

The second prototype YB-49, S/N 42-102368, was burned and destroyed during a ground taxiing accident at Edwards Air Force Base. This left the YRB-49A, a strategic reconnaissance aircraft as the sole remaining Flying Wing. This photo reconnaissance aircraft had four 5,000 pound thrust Allison J-35-A-19 engines in the wing and two more suspended in pods below the wing. Photographic equipment was installed in the tail cone bay just below the centre section. It had an empty weight of 88,500 pounds and a gross weight of 117,500 pounds and a maximum gross weight of 206,000 pounds. It had a top speed of better than 550 miles per hour and it was the same dimensions as the YB-49.

The clean lines of this flying wing was broken by two engine pods suspended below the wing leading edge to carry two Allison J-35 turbo jet engines. The YRB-49-A first took to the air on May 4, 1950. Tests were conducted at Edwards Air Force Base for a period of time, but stability tests in the program hampered further production. Plans were made to install a stabilizing device made by Minneapolis Honeywell to overcome stability problems. This was the same type of device installed in the B-47 Stratojet Bomber for stability guidance. The YRB-49A was designed as a fully operational photo reconnaissance plane. It had useful loads and better performance in speed and range than the YB-49. In early 1952, the huge flying wing was flown to Ontario International Airport to the Northrop facility where the installation of this stability device was to be installed. Funding for this project was dropped, however, by the Air Force, and the aircraft remained in dead storage for a period of time.

In October, 1953, the Air Force ordered the YRB-49A to be scrapped. Crews were sent from nearby Norton Air Force Base to complete the salvage project. The aircraft was towed from the Northrop facility at the southeast end of the field to a site adjacent to the Air National Guard area where it was dismantled and cut up for scrap. The huge ship had been sitting in the grape vineyards weathering the onslaught of dust, wind, rain and sun for some time. One major Los Angeles newspaper stated: “It is hard to believe we have scrapped a design which is as modern as the planes today. Perhaps we will have to wait twenty years or longer before we find out the true significance of our mistake.” True, the wing did have its share of problems; however, with adequate funding, these problems could have been worked out to prove that the wing did hold a place with the Air Force.

The Flying Wing was years ahead of its time, but it was caught in a budget squeeze between the faster B-47 Stratojets and the long-range B-36 intercontinental bombers. Politics also played an important part in the defeat of the B-49 Flying Wing.

The YRB-49A had a top speed of 512 miles per hour at 40,000 feet. It had a range of 3,500 miles non stop without aerial refuelling.

A comment must be made on the B-49 design competition: During this period, 1948 - 1952, a former Northrop competitor employee became Secretary of Defence under President Truman’s administration. Being a former officer of a competing firm to Northrop, some significance in the Air Force’s selection of the B-36 over the B-49 should be noted. One day a high government official was sent from Washington to visit John Northrop. A meeting took place whereby John Northrop was told that his B-49 Flying Wing Bomber would be produced for the Air Force; however, it had to be built by Convair in Fort Worth, Texas or the Air Force would not buy his Flying Wing design. John Northrop replied that he and his employees had built the Northrop Company and organization over the years and he owed a debt of loyalty to his employees. He stated that if the aircraft was to be built at all it would be built by his people at the Northrop factory in Hawthorne, California. The rest is history. The Air Force ordered the B-36. The significance of this fact should be made clear to future generations investigating the story of the Northrop Flying Wing.

Northrop-Grumman B-2 Spirit "stealth bomber."

The B-2 is a multi-role advanced technology bomber with stealth characteristics. The B-2's low observable, or stealth, characteristics give it the ability to penetrate an enemy's most sophisticated defences. This low observability allows it to fly more flexible routes at higher altitudes, thus increasing its range and providing a better field of view for the crew and the aircraft's sensors. The low observability traits of the B-2 include greatly reduced infrared, acoustic, electromagnetic, visual and radar signatures. These signatures make it extremely difficult for even the most sophisticated defensive systems to detect, track and engage the bomber. Many aspects of the stealth feature remain classified. However, the B-2's composite materials, special coatings and flying wing design all contribute to its stealth. The first B-2 rolled out of its hangar at Air Force Plant 42, Palmdale, Calif., in November 1988. Its first flight was July 17, 1989.

The most famous flying wing was the only successful one, the Northrop-Grumman B-2 Spirit "stealth bomber." It was first started by the Northrop Corporation in the late 1970s (the contract was awarded in 1981; its first flight took place in 1989) but did not become fully operational until a decade and a half later due to its complexity and numerous initial problems.

The B-2 was an example of modern technology finally catching up with an earlier idea. By the 1970s, aircraft designers were deliberately developing airplanes like the F-16 that were unstable in flight, and therefore inherently manoeuvrable, controlling them in flight by sophisticated modern computer control systems. Computer control systems now also made it possible to control the unstable flying wing design.

The flying wing still offered excellent performance and fuel efficiency advantages. But Northrop's designers also chose a flying wing configuration because it offered advantages for stealth; a vertical tail such as found in a conventional aircraft reflects radar energy. Eliminating it increased the aircraft's stealthiness, particularly from the side. The B-2 is capable of carrying as many bombs inside it as the larger B-52 and flying just as far. Although only 21 of these planes are in service, they played a major role in the 1999 bombing of Yugoslavia, which had a sophisticated air defence system, and are generally regarded as an amazing technological achievement, albeit a very expensive one.