by E.T. Wooldridge
The final chapter in the odyssey of Jack Northrop's quest for the true
flying wing is a microcosm of all of the disappointments and glorious
moments one could expect in the development of an aircraft as
unconventional as the flying wing bomber. The piston-engined XB-35, and
its jet-powered successor, the YB-49, were immensely pleasing to the eye,
but to conservatives within the aeronautical community, they probably did
not "look right", and therefore their ultimate success was in doubt.
The flying wing bombers enjoyed all the usual financial
support and governmental interest normally associated with a wartime
program. They also suffered through the chaotic period that came with
war's end. The program endured, however, because of the enormous potential
demonstrated by the unique aircraft. The enthusiasm for the program that
was demonstrated by the Northrop "family" was shared to a great extent by
many of the technical and management people of the Army Air Forces. Their
foresight, assistance, and encouragement kept the development program
going through the rough times.
Project MX-140, as the bomber program was called, was
officially initiated by contract action on November 22, 1941, following
previous discussions between Northrop and Air Force officials regarding
performance requirements for a high altitude, long range, heavy
bombardment airplane. The numbers that spelled out the airplane's vital
statistics in formal Airplane Specifications NS-9A gave no hint of the
sheer expansiveness of the airplane, and its spectacular performance. They
also gave no hint of the problems that would attend its design,
construction, and flight evaluation.
In size, the XB-35 would dwarf the B-17 Flying
Fortress, with wing area and gross weight almost three times those of the
legendary heavy bomber. The unconventional control system reflected years
of study, wind tunnel tests, and flight test data gleaned from the N-1M
and N-9M programs. The elevons and rudders were power operated. Thus, it
was necessary to provide an artificial "feel" to the controls for these
surfaces. This was accomplished by springs attached to the control wheels
and rudder pedal mechanisms which returned the controls to neutral and
provided the "feel" necessary to prevent over-control of the rudder and
aileron movement of the elevons. "Feel" to the operation of the control
columns for elevator control was provided by ram air pressure in a bellows
attached to the control columns.
Trim flaps, elevons, and landing flaps were arrayed in
order from each wing tip inboard along the trailing edge of the wing. The
electrically actuated trim flaps at the wing tips were used by the pilot
in much the same manner as elevator or aileron tabs. Their primary purpose
was to balance the large diving moments produced by the split trailing
edge landing flaps, minimizing the upward deflection of the elevons and
thus permitting them to be deflected over a greater range as elevators.
The trim flaps could also be operate differentially to counteract
unbalanced rolling moments.
Rudders consisted of split flaps that were incorporated
as an integral part of the trim flaps at the trailing edges of the wing
tips. Operated one at a time by the pilot's movement of the corresponding
rudder pedal, the surfaces deflected above and below the trim flap.
Simultaneous movement of the rudder pedals, which were not interconnected,
opened both rudders for speed control. Despite the unconventional
arrangement and function of the control surface, the conventional control
column with wheel and rudder pedals made the pilot feel right at home.
Contributing to increased longitudinal stability at
high angles of attack were wing tip slots with automatically controlled
cover doors. These doors were set to open at high lift coefficients,
preventing wing tip stall and increasing stability. A switch actuated by
the landing gear also opened the doors when the gear was down.
One of the primary concerns in the layout of the
aircraft was the cockpit design. Despite unorthodox configuration, space
was not a problem. The aircraft's cockpit featured convenient control and
instrument arrangements and excellent visibility.
Conventional instruments and control switches are arranged in a slightly
unconventional manner in the XB-35 cockpit. Flight instruments are arrayed
on the vertical panel between the pilot stations; radio equipment and prop
controls are located on the pedestal separating the pilot stations. One
set of throttle controls is suspended from the top of the cabin between
the pilot and co-pilot, another is mounted in a quadrant at the engineers
table further aft, along with the mixture controls.
The pilot seated in the plexiglass bubble to the left
of the aircraft centreline. The co-pilot was to the right of and below the
pilot, behind a large window in the leading edge of the wing. An
engineer's station was also in the forward part of the crew nacelle, as
were stations for the radio operator, navigator, bombardier, and gunners.
The mid-section of the crew nacelle had sleeping facilities for a relief
crew of six people, a requirement for operational missions of 10,000 miles
where crew fatigue would be a primary consideration. The after section
contained the gunner's station. The seven-foot headroom in the crew's
quarters was certainly adequate, and the accommodations were the first of
such extent and complexity to have been incorporated into such a radical
A brief look at the overall arrangement would not be
complete without at least some reference to the "main battery" of the
XB-35-its eight bomb bays. Capable of carrying 10,000 pounds of
conventional bombs (but not an atomic weapon), the bays were incorporated
in the wings, arrayed four on each side of the crew nacelle.' Defensive
armament consisted of twenty 0.50 calibre machine guns contained in seven
remotely controlled turrets: four on the wing, two on the crew nacelle,
and a tail stinger.
This striking photograph, staged though it may be, dramatically shows the
XB-35's "Achilles' heel" -the eight four-bladed, contra-rotating
propellers. Constant troubles with government furnished gearboxes severely
restricted the further development of the XB-35 flying wing
The power plants were also vital to the successful
operation of this revolutionary weapons system. They consisted of four
Pratt & Whitney Wasp Major engines, one pair each of R-4360-17 and
R-4360-21 series equipped with single stage GE turbo-superchargers, each
delivering 3000 hp. The "Achilles' heel" of the installation was the
propulsion power train. Each engine was coupled to a remote gear box
assembly by an extension drive shaft. Two sets of four-bladed, dual
rotating, reversible pitch, full feathering, Hamilton Standard propellers
were mounted on dual concentric shafts extending from each gear box. The
engines were completely enclosed within the wing, an arrangement that
imposed severe requirements on the aircraft's structure. Superchargers,
intercoolers, oil coolers, and fans for ground-cooling and cooling at low
speeds were located in the wing, as were cooling ducts and controls to
diffuse the air around the engines and expel it through flaps near the
Basic design similarities between N-9M and XB-35 are evident in this
photograph of the XB-35, under tow prior to taxi tests at Northrop in May
1946. Split-flap rudders attached to the pitch trimmers, elevons and
landing flaps are along the trailing edge; automatic wing slot is visible
just aft of the leading edge on the left side.
Translating 100 pages of statistics and technical terms
into 100 tons of complex, futuristic airplane proved to be an almost
insurmountable task. From contract approval in November 1941, to first
flight of the XB-35 on June 25, 1946, there were interminable delays. At
one time or another, changes in priorities, design and engineering
difficulties, problems with ground testing engines, shortages of
engineers, indecision by management, constant shortages of government
furnished equipment (GFE), and a myriad of other factors contributed to
the lengthy production process. Of all the obstacles to orderly progress,
the most frustrating involved the highly unsatisfactory working
relationship between two major aircraft builders, Northrop and Martin.
Following an initial contract for one XB-35 airplane,
approved November 22, 1941, Northrop received an order for an additional
XB-35 as a backup in January 1942. Later that year, another 13 service
test models were contracted for, to be designated YB-35. By June 1943,
with a production contract for 200 B-35s on hand, and the first flight
date still out of sight, it was apparent that Northrop production and
engineering facilities, already heavily committed to production of P-61
Black Widow night fighters, were inadequate for the job. If the program
was to proceed, engineering and production assistance would have to come
from some other source.
By the end of June 1943, the Glenn L. Martin Company of
Baltimore, Maryland, at the AAF's request, had contracted to assist
Northrop in engineering the XB-35 and YB-35 and also to manufacture 200
production B-35s. Delivery of the first production airplane was to be in
June 1945. From a tactical and logistical standpoint, there was no further
need for Martin's B-33 Super Marauder. The production contract was
cancelled and the available engineering talent was diverted to the XB-35
The engineering "partnership" that evolved between
Northrop and Martin not only failed to produce a single B-35, but also
engendered confusion, delays, and even ill will. Engineering work was
carried out simultaneously at both companies on "X," "Y," and production
airplanes, resulting in indecision, lack of coordination, and unresolved
questions of priorities and responsibilities. Loss of engineers to the
military draft aggravated an already untenable situation. As of March
1944, Martin had made no commitments to materials and had not started
tooling. The program was already 18 months behind schedule and relations
between Northrop and Martin were considerably strained.
In May 1944, the AAF reviewed the entire program. It
was the opinion of some officials that the attitude of Martin management
was a significant factor in the lack of progress to date. Never
enthusiastic about producing any airplane not of their own design, Martin
continually put forth more reasons for not continuing their part of the
production program. Martin management expressed little faith in the B-35
as a practical airplane. The AAF decided to cancel Martin's production
contract, with the understanding that Martin would continue to give
Northrop engineering assistance on the "X" and "Y" models. Additional
engineering assistance would be made available from the Otis Elevator
Company. No production engineering was to be undertaken at that time. In
effect, it was a conscious decision that the B-35 would be a post-war
December 1944, marked a significant turning point in
the development of the Flying Wing bomber. By that time, both Germany and
England were using turbojet-powered aircraft in combat. The Messerschmitt
Me 262 first appeared on combat in July 1944, followed shortly by the
first victory of the British Gloster Meteor over a German V-1 missile. In
the United States, the Bell XP-59A Airacomet had flown in 1942, and by
late 1944 the Lockheed P-80A Shooting Star was almost operational. It was
becoming obvious that the world was on the threshold of the jet age and
piston engined warplanes such as the B-35 would eventually become
obsolete. On the other hand, a B-35 fitted with turbojet engines began to
look extremely attractive.
Consequently, in December 1944, series of modification
and conversion programs began that lasted until the final days of the
Flying Wing bomber. Proposals for changes in the aircraft mission,
combined with alternative power plant arrangements led to a bewildering
variety of aircraft configurations and designations. After years of
conversion and modification programs that ensued, only six were completed
and flew, three of which had piston engines, and three with turbojets.
It was another year and a half after the modification
proposals in December 1944, before an XB-35 would finally take to the air
on its maiden flight. It was a frustrating period marked by engine
development problems, delays due to lack of experience in construction of
very large aircraft, late deliveries of major GFE items, and the acute
conversion problems experienced by the defence contractors with the end of
World War II.
The majestic XB-35 (42-13603) moved for the first time
on its own wheels and under its own power on May 16, 1946. The occasion
was a slow taxi test, and at the controls was the Northrop test pilot who
would shepherd the Flying Wings through four turbulent years of flight
tests, Max Stanley.3 Accompanying Stanley as co-pilot was Fred
Bretcher, who would be at his side during much of the flying program.
As the XB-35 began to move slowly down the 100-foot
wide runway at Hawthorne, its 172-foot wing span seemed to dwarf even the
building of the nearby Northrop plant from which it came. To Jack
Northrop, standing at the flight ramp, the sound of four R-4360s running
at the same time, even at taxi power setting, must have been overwhelming.
As Max Stanley gave him a "thumbs up" at the conclusion of the
satisfactory test, Jack Northrop surely must have been elated at this sign
of progress and the prospect of a first flight in the not too distant
The day finally came. After dozens of high-speed taxi
runs, during which speeds as high as 115 mph were attained, the aircraft
seemed ready. June 25, 1946, was picked for first flight. Only a small
crowd of sightseers and media people watched Max Stanley, Fred Bretcher,
and Flight Engineer O.H. Douglas climb up into the flight deck, which by
10:00 am was like an oven in the hot California sun. Absent were the
thousands of designers, engineers, and shop workers who had laboured for
years over the engineering and construction of the bomber. They had been
restricted to their desks and work stations by company executives
concerned over crowd control during the momentous occasion. Absent also
was the man whose creative genius had spawned the giant wing, Jack
Northrop, who, abiding by company policy, also remained at his desk, in an
incredible display of self discipline.
"This is it!" With those words, Max Stanley advanced
the throttles and, with 12,000 hp pushing the huge wing along, the XB-35
thundered down the narrow runway at Hawthorne. At 120 mph, Stanley slowly
eased the control column back and at 10:32 A.M., the Flying Wing flew for
the first time. Finally, after years of planning and experimenting, Jack
Northrop had accomplished what Junkers, Soldenhoff, and other early
pioneers had only dreamed of.
In an historic moment Max Stanley lifts the world's largest flying wing
off Northrop Field on its first flight on June 25, 1946. The uneventful
flight terminated at Muroc Air Base.
The first flight was essentially a ferry flight from
Northrop Airport to Muroc Army Air Base. The idea was to get to Muroc with
a minimum of trouble, but at the same time to learn about the flying
characteristics of the airplane. Stanley tested the controls with the
landing gear up and down several times. Highest airspeed attained was 200
mph, as the Flying Wing, with its P-61 Black Widow chase plane in company,
cleared the mountains and began its descent to Muroc. As a precautionary
measure, a no-flap approach was made, with a smooth touchdown at 112 mph.
The 44-minute flight was uneventful, except for erratic operation of a
propeller governor. Everyone associated with the project was jubilant,
anxious to press on with the flight testing and prove the design once and
But the minor problem with the propeller governor did
not fade away. The XB-35 flew twice more in the next three months,
accumulating only three hours of flight time by mid-September 1946.
Problems with the Hamilton Standard propeller governors became chronic,
with the propellers continually "hunting" around a constant speed setting
and "creeping" in fixed pitch during air operations. Additionally, there
was evidence that the huge counter-rotating propellers were operating
under excessive stress, leading to a restriction of 80 hours operating
time due to the danger of fatigue.
Another major problem with GFE arose. Troubles centred
around the gear box assembly that coupled each engine to its propeller by
means of a drive shaft from engine to gear box, and a dual concentric
shaft from gear box to the counter-rotating propellers. Propellers and
engine vibration caused frequent failures of the gear boxes. A flexible,
vibration absorbing gear box mount was a vital necessity for successful
Regardless of developmental problems, the Flying Wing in the air was the
epitome of style and grace, exhibiting an extraordinary quality that
caught the fancy and imagination of the public.
At the beginning of 1947, the Flying Wing program
consisted of one XB-35 flying, albeit occasionally, one XB-35 about to
finish engineering inspection in March, two YB-49s (the jet engine
configured B-35) and six YB-35s (built to XB-35 specifications) either
complete or in the final stage of assembly. The remaining five YB-35s on
the existing contract were to be equipped with more modern navigation and
weapons systems, and thus were to be designated YB-35As.
The first XB-35 flew only intermittently during 1947,
plagued by landing gear doors failing to retract and the continuing gear
box malfunctions. The second XB-35 (42-38323) flew for the first time
almost one year after the first, on June 26, 1947. It too, began to
experience the same difficulties as the first aircraft. In desperation,
the Air Materiel Command cancelled dual rotation propellers for the YB-35
and decided to use single rotation gear boxes and 15-foot diameter
Hamilton Standard propellers, despite the resulting deterioration in
performance. In April, both XB-35s were grounded for installation of the
changes. Flight tests did not resume until February 1948.
The troublesome contra-rotating propellers eventually gave way to four new
single-rotation propellers, shown here installed on the first XB-35.
Despite the change, the piston-engined B-35 eventually became a victim of
the jet age
As a result of the 1944 study of the possibilities of
converting the YB-35 to turbojet engines, two of these aircraft were
modified to the YB-49 configuration. In the altered aircraft eight
4000-pound thrust TG-180 (J35) engines, designed by General Electric and
built by Allison, were substituted for the four R-4360 reciprocating
engines. Aside from the absence of propellers the most noticeable change
was the addition of four vertical fins to the trailing edge of the wing.
These mammoth fins, twice the height of a man, were added to provide the
directional stability originally provided by the four propeller shaft
housings and propellers. The dorsal fins were extended forward to a point
near the leading edge of the wing to inhibit spanwise boundary-layer flow.
The whole installation went entirely against Northrop's concept of a pure
flying wing, but for a wing of that size, some protuberances were
By trading props for tailpipes and adding vertical fins, the B-35 acquired
a new designation, B-49, and a new lease on life. Gross weight increased
30,000 pounds, maximum bomb load decreased from 144,800 to 32,000 pounds,
and range decreased to about 4900 miles, despite the addition of fuel
Shown here is the right side bank of four J35 turbojet engines flanked by
two fixed vertical fins. At the lower left is the right side landing flap
in the extended position.
The eight-jet YB-49 (42-102367) was rolled out and
unveiled to an admiring press at Hawthorne on Monday morning, September
29, 1947. The first taxi test was on October 20, with Max Stanley, Fred
Bretcher, and O.H. Douglas at their accustomed crew stations.
Cockpit of the YB-49 (42-102367) has a cleaner look to it compared to that
of the XB-35. Two overhead throttles for eight jet engines replace the
four piston engine throttles; the centre pedestal is less cluttered with
the absence of propeller and some radio controls
The first flight on October 21, 1947, was from
Hawthorne to Muroc; the 34 minutes in the air were uneventful. Orva
Douglas summed up the reaction of the crew: "With its smooth (vibration
free) flying, quiet operation, and phenomenal performance, the YB-49 is a
Flight testing of the YB-49 began in earnest, the
aircraft flying almost as much time in the next two months as the two
XB-35s had flown in 18 months. Nevertheless, problems with props and gear
boxes were immediately replaced by failures of auxiliary power units that
supplied current to the electrical system of the airplane, poor
reliability of the J35 turbojet engines, and marginal stability that
compromised the capability of the YB-49 to perform the bombing mission for
which it was intended.
Highlight of the YB-49 test program was the long range test flight on
April 26, 1948. The aircraft took off with a gross weight of 192,000
pounds, and flew a distance of 3528 miles at a true airspeed of 388 mph. A
round robin course over the California and Arizona desert was flown. The
only mishap was that a rough running engine had to be shut down two hours
before landing at Muroc.
For most negative aspects of the YB-49 development
program, however, spectacular demonstration of performance occasionally
occurred which evoked superlatives. One such event was the highly
successful long range test flight of the YB-49 on April 26, 1948. On that
date, the aircraft remained aloft for 9.5 hours, of which 6.5 hours were
flown at an altitude of 40,000 feet. The five-man crew for the flight
consisted of Max Stanley, Fred Bretcher, and Orva Douglas, augmented by
Air Force Captain Jay Wethe and Northrop flight engineer Don Swift. The
record breaking flight prompted high praise from General Hoyt S.
Vandenberg, Chief of Staff of the U.S. Air Force.
It was an encouraging, well-deserved accolade for the
Northrop team. Coming on the heels of the first flight of the second YB-49
(42-102368), flown on January 13, 1948, by Major R.L. Cardenas, it was
followed in May by the first flight of the third and last of the B-35
series, the YB-35 (42-102366). All three B-35s were now equipped with the
single rotation propellers and gear boxes.
Hard on these tangible signs of progress came disaster.
On June 5, 1948, after accumulating almost 57 hours of flight time, the
second YB-49 crashed and was destroyed. Killed in the crash were: Major
D.N. Forbes, pilot; Captain Glen W. Edwards, co-pilot; Lieutenant E.
Swindell, flight engineer; Mr. C. Leser, observer; and Mr. C. LaFountain,
The aircraft was on its twenty-fifth flight at the time
of the accident. Recent flights had been devoted to the performance tests
of the program, with Forbes as pilot and Edwards as co-pilot on all
flights except #23, where Askounis acted as co-pilot in place of Edwards.
Flight engineer for these flights was Lieutenant Swindell.
Major Forties and his crew had taken off from Muroc in
the early morning ostensibly for a performance test flight. Routine
position reports over the Antelope Valley test range were received for
about an hour. The aircraft was observed to crash in the desert about 20
minutes after the last report. The major portion of the airplane landed
inverted, with no apparent horizontal velocity, and much of the airplane
was destroyed in the explosion and fire that followed.
Parts of the airplane, including the outer wing panels
and flap and elevator parts, were found in a narrow area extending two or
three miles from the wreckage. During the investigation that followed, it
was impossible to arrive at an incontestable conclusion regarding the
cause of the accident. A major structural failure had obviously occurred
in flight. Many specific causes were considered: exceeding flight
restrictions, tumbling resulting from a stall, instability due to extreme
aft centre of gravity due to improper fuel usage, unintentional nose-up
trim flap motion, hydraulic control system malfunction; the possibilities
seemed endless. All were examined, many were discarded as impossible, some
left open as possibilities.
In the final analysis, it appeared that the crash was
caused by simultaneous failure of both outer wing panels from a positive
loading condition. The failure could have been due to loads caused by
excess normal acceleration, i.e., the airplane was overstressed during a
high-G pullout. One of the most plausible explanations was that the
overstress occurred during recovery from a stall or post-stall manoeuvre.
The setback in the program turned out to be temporary;
the airplane's potential for a variety of roles was well recognized by the
Air Force. A review of the Strategic Reconnaissance Program by the Air
Force subsequently led to a formal contract in September 1948, for 30
reconnaissance versions of the B-49, designated the RB-49A. Even before
the contract was signed, Northrop was instructed in June to arrange
production of the airplane, except for an absolute minimum number, at the
government-owned Fort Worth facility of Consolidated Vultee Aircraft
Corporation (Convair). The Convair Fort Worth plant was engaged in B-36A
production, to which only about 70 percent of the facility was devoted.
With Northrop's production capacity of only three bombers per month at its
Hawthorns facility, the shift would take advantage of Convair's unused
The proposed subcontract was an unusual one for
peacetime. It appeared to mark the emergence of the B-49 as a major factor
in the strategic forces of the jet age. In reality, the days of the Flying
Wing were numbered.
As B-49 testing continued and production plans took
shape, the B-35 program continued to experience serious problems; doubts
arose about the airplane's utility as an operational bomber, particularly
in view of force level cutbacks and the inability of the Flying Wing to
carry an atomic bomb. Vibration difficulties were being encountered with
the single rotation propellers, engine cooling fans continued to fail from
metal fatigue, and considerable maintenance problems were experienced with
the intricate exhaust system of the R-4360 engines. Many configurations of
the B-35 emerged, most involving some sort of conversion to turbojets. One
proposal, which was well into the fabrication stage in late 1949, was the
conversion of a YB-35 to a combination of turbojet and turboprop engines.
Designated EB-35B, the airplane would have six turbojets: four in the
wing, and two externally mounted below the wing, as well as two
wing-mounted Northrop XT-37 Turbodyne engines.
The XT-37 Turbodyne was developed by the Northrop-Hendy
Company, a jointly-owned subsidiary with the Joshua Hendy Iron Works.
Research on the turbine that resulted in the Turbodyne dated back to 1939,
when Vladimir Pavlecka, then Northrop's chief of research, interested Jack
Northrop in the potential of gas turbine power plants. Funded by a joint
Army-Navy contract, the turbine development continued during the war
years, and the first engine was completed in 1945. It was subsequently
destroyed during tests, but a second machine continued in development. By
1950 its 50-hour endurance test was completed, delivering a
record-breaking 7500 hp continuously. At the time, it was the most
powerful aircraft power plant in the world, capable of delivering 10,000
hp with a suitable propeller. On the EB-35B, two Turbodynes were to drive
large counter-rotating pusher propellers. With the cancellation of the
EB-35B in 1949, prospects for flight tests of the engine ended. In 1950,
at the direction of the Secretary of the Air Force, the patents, name, and
technical data were released to the General Electric Company.
In November 1948, another step was taken toward the
ultimate dissolution of the B-49 project. During informal discussions
about recent bombing tests of the YB-49, Major Robert L. Cardenas, Air
Force test pilot on the project, was quoted in official Air Force records
as saying that the airplane was "extremely unstable and very difficult to
fly on a bombing mission ... because of the continual yawing and the
pitching which was evident upon application of the rudders, undoubtedly
due to the control arrangements or elevons peculiar to the YB-49." Until
aerodynamic deficiencies could be corrected, it was the opinion of Colonel
Albert Boyd, Chief, Flight Test Division at Murk, and Major Cardenas, that
the YB-49 was unsuitable for both bomber and reconnaissance work"
Subsequently, Major Cardenas stated for the record that
the airplane was marginally stable, rather than "extremely unstable." On
November 16, 1948, an official Air Materiel Command report on the bombing
evaluation, which was conducted under manual conditions, i.e., without
autopilot, reiterated the inadequacies of the YB-49 under the test
conditions, but referred to the "marginal directional stability of the
aircraft in fight." Installation of a satisfactory autopilot was
considered a top priority.
On December 29, 1948, a Board of Senior Officers met to
study the Air Force procurement program, and consider a proposed
termination of the RB-49 program. The Board recommended cancellation of
the 30 RB-49s.
On January 11, 1949, the Air Materiel Command directed
Northrop to terminate work on all phases of the reconnaissance version
except for completion and test of one YRB-49A, a six engine version
equipped with special reconnaissance equipment. Conversion of certain
YB-35s to jet engines continued.
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-35ís to Flying Wing B-49 1t Bombers.
The decision in February 1949, to salvage, or scrap the
two XB-35s (4213603 and 42-38323) and the YB-35 (42-102366), which were
the only piston-engined Flying Wings in flying status, spelled the end of
that phase of the program. With only one remaining jet-powered YB-49
(42-102367) still flying, the future of the program looked bleak. In
February, the YB-49 had a brief moment of triumph in an otherwise
On February 9, 1949, the YB-49 flew non-stop from Muroc
to Andrews Air Force Base, Washington, D.C., in 4 hours, 25 minutes, at an
average speed of 511 mph. Major Cardenas was the pilot, with Captain W.W.
Seller as copilot, and Max Stanley on board as pilot observer. The flight
time compared favourably with the official transcontinental record of 4
hours, 13 minutes, 26 seconds, set by Colonel William H. Councill in a
Lockheed P-80A on January 26, 1946. Councill had averaged 580 mph for the
2435-mile trip. The YB-49 flight came on the heels of a similar flight by
its competitor, the Boeing XB-47, which the previous day had been flown by
Major Russ Schleeh from Moses Lake Air Force Base in the state of
Washington to Andrews in 3 hours, 46 minutes, at an average speed of 607
The flight on February 9 was the first public
demonstration of the airplane's potential. At Andrews, it was exhibited to
the public. President Truman was heard to observe, as he finished
inspecting the giant Flying Wing: "This looks like one hell of an
airplane. We ought to have some." This offhand comment may have brought
encouragement to Jack Northrop, but the effect would be short lived.
Both the versatility and the weak point of the YB-49
were dramatically demonstrated during the return flight to California,
when it became necessary to cut four of the eight jet engines in flight
because of oil starvation due to faulty maintenance at Wright Field. Major
Bob Cardenas made an uneventful, unscheduled landing at Winslow Airport,
Arizona with three engines operating on one side, and one on the other!
During the early part of 1949, Max Stanley conducted
autopilot tests on the YB-49, and the Air Force made preparations to begin
bombing tests with the E-7 autopilot in May 1949. Unfortunately, the
official results of these tests are not available, but Max Stanley recalls
the tests to evaluate the airplane as a bombing platform:
Both Northrop and Air Force pilots participated in this
program. The bombardier was an Air Force officer using the then highly
secret Norden bombsight. After an evaluation by the Air Force of these
tests, the aircraft was declared suitable for its mission.'
During April and June 1949, Major Russ Schleeh, who had
replaced Major Cardenas on the Flying Wing project, flew the YB-49 11
times, evaluating the aircraft as a bombing platform both with and without
the autopilot. According to Major Schleeh, the bombing results were very
poor. In 1982, he recalled some of the problems.
"!It was noted in
the movies taken from a chase airplane that the 100-pound
bombs dropped from the bomb bay almost without exception showed a pitching
and oscillating movement, which at that time was attributed to the
turbulence in the bomb bay. This no doubt caused some of the bombing
inaccuracies we were experiencing. I cannot agree with the statement that
the aircraft was declared suitable for its mission, as I would never have
made such a statement for a number of reasons."
Nonetheless, Air Force interest in the program dwindled
as the year wore on, as did available funds. The eight-jet version would
not be available until January 1950, and would have an inadequate
operating radius; the six-jet model, the YRB-49A, planned for 1951, would
be slower than the B-47; and the Turbodyne-equipped version would not be
available until 1953, putting it in competition with the superior
performing, all-jet B-52.
In the meantime, negotiations between Northrop and
Convair officials over a proposed merger, originally proposed in July 1948
by the board chairman of Convair, Floyd B. Odlum, failed to produce an
agreement satisfactory to either side.
In November 1949, the Air Force cancelled plans to
convert the remaining YB-35s. All YB-35s were ordered scrapped, with the
exception of one intended for use in the YRB-49A project. Despite Northrop
efforts to save the program, no reprieve was granted. Scrapping of the
B-35s began in January 1950; the lone flyable YB-49 was destroyed on March
15, 1950, in an accident caused by nose landing gear failure during
simulated takeoff runs by Major Russ Schleeh.
On May 4, 1950, with the entire Flying Wing program in
a shambles, the last of the majestic aircraft took to the air on its first
flight. Even this last of Jack Northrop's Flying Wings must have been
somewhat of a disappointment to him, as aesthetically pleasing and
graceful as the airplane appeared to the casual observer. In addition to
four vertical fins appended to all of the B-49 family for directional
stability, the YRB-49A had two of its six Allison J35A-19 engines
suspended below the wing, to allow for greater internal fuel capacity. The
idealistic goals of a completely aerodynamically clean airplane had given
way to drastic modifications because of military requirements.
The YRB-49A was flown in an abbreviated series of
flight tests at Edwards Air Force Base, then placed in storage at the
Northrop facility at Ontario International Airport, California. It was
officially authorized for reclamation in November 1953, and dropped from
the Air Force inventory a year later.
Why did the Flying Wing fail to go into production? A
popular explanation, with a ring of truth to it, is that the aircraft was
30 years ahead of its time. Even its most ardent supporters would not deny
that it had problems. The B-35 series was doomed by overwhelming
difficulties with propellers, gearboxes, and maintenance problems with the
complicated exhaust system. Perhaps even more pertinent, it was overtaken
by the jet age.
The B-49 was hampered by marginal directional stability
that compromised its ability to perform bombing or reconnaissance
missions. Pilots and engineers close to the program recognized that
stability deficiencies would have been corrected with a proper autopilot
and stability augmentation devices, given adequate time and support for
The YRB-49A's performance would not have measured up to
that of its competitors by the time a protracted development program had
run its course. The airplane and the eight-engine versions were basically
400 mph airframes designed for piston engine performance. Replacing
R-4360s with J35s did not automatically result in jet age performance.
For Jack Northrop, it was obviously a bitter
disappointment to have devoted so many years of his professional life to a
dream and to see it abruptly terminated. The most unfortunate aspect of
the entire affair is that not one flyable aircraft was retained for a
sustained research and development program to thoroughly explore all of
the potential benefits and pitfalls of the flying wing design. The
distinguished aviation and space pioneer Dr. Theodore ion Karman put one
more slant on the subject, when he expressed the views of all those who
have admired an airplane purely for its grace and beauty.