Since the days of the Wright brothers, aeronautical engineers have experimented with the design of the "Flying Wing": tailless aircraft without a defined fuselage. All components of the machine and the pilot himself are located in the plane of the wing. In theory, this is the most aerodynamic and efficient design possible. In practice, however, it turns out that without stabilization and features characteristic of a conventional aircraft, such wings are very difficult to control.
Before that, you and I considered the "Flying Wing" of the Third Reich. Now let's look at the development of this direction already in the USA
Northrop started the full-scale design of the XB-35 in 1942, when the tests of the N-9M were just being prepared. Soon, two models of the future machine with a wingspan of 2.44 m and 4.88 m, reduced by ten times, were built, which underwent a research program in a wind tunnel.
Based on the successful results of the blowdowns, Northrop decided to start building the first prototype bomber in January 1943.
The aviation world had never seen anything like it. The huge all-metal "flying wing" had a wingspan of 52.42 m, a height of 6.12 m, and an area of 371.6 m2. The empty weight of the aircraft was more than 40 tons, the maximum take-off weight was 95 tons, while the load weight reached 54.5 tons.
In front of the wing were installed four Pratt and Whitney WaspMajor piston engines - two types R-4360-17 and two types R-4360-21 with a capacity of 3000 hp. each. All engines were powered by General Electric turbochargers. The transmission from the internal engines to the four-bladed Hamilton Standart Supermatic propellers with a diameter of 4.67 was carried out by a shaft 7.2 m long. From the external - 4.8 m. The protruding fairings of the shafts also improved the directional stability of the machine.
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Slots were made in the front edge of the machine to cool the machine units. Through which the air entered the special injection chambers located in the wing nose.
The complex design of the bomber's power plant units gave the developers many problems: gearboxes were constantly damaged, fires broke out, etc. All this threatened the disaster of the experimental machine. Therefore, the refinement of power units has become the main work of the designers.
The flying wing's landing gear was three-wheeled, retractable. The twin wheels of the main landing gear had a diameter of 1.67 m, the single nose - 1.42 m.
Achieving the stability of the XB-35 in flight did not cause any particular difficulties. It was achieved by the sweep of the wing and the selection of the appropriate profile, as well as the thoughtful installation of pushing screws behind the aircraft's center of gravity.
The aircraft was controlled by flaps replacing the rudders with the usual elevons for "flying wings", as well as by flaps and trim tabs.
To improve the working conditions of the pilots and facilitate piloting on the XB-35, hydraulic boosters were used. In addition to them, the aircraft was equipped with an autopilot by Minneapolis Honnywell, designed specifically for this aircraft.
The crew of the XB-35 consisted of nine people: a pilot, co-pilot, bombardier, navigator, flight mechanic, radio operator and three gunners. If necessary, the crew could be increased to 15 people.
The mass of the bomb load when performing a task at a distance of 12100 km was supposed to be 4500 kg.
To protect against enemy fighters, the bomber had powerful defensive armament: 12 large-caliber Colt-Browning machine guns and two automatic cannons. Two turrets with twin 12.7 mm machine guns were installed on the upper surface of the wing, and two turrets with quad 12.7 mm machine guns were installed on the lower surface; at the rear in the aft installation - two 37 mm cannons.
The aircraft had practically no protruding parts, with the exception of the shaft fairings, cockpit canopy and turrets.
Such properties of the XB-35 were the closest approach to the ideal "flying wing" at that time. The only thing that upset was the delay in the construction of the car. The Second World War has already ended, and the plane has never taken off.
The first prototype of the bomber was delivered in the strictest secrecy to the US Air Force Muroc Army Air Field for flight tests only at the beginning of May 1946, where the first taxiing along the runway at a speed of 50-65 km / h began on May 16.
In early June, he already made his first runs along the strip, reaching a speed of 180 km / h. After thirty such runs, it was decided to lift the plane into the air.
On July 25, 1946, having run along the runway for about a kilometer, the XB-35 smoothly lifted off the ground and went on its first flight. The crew included Commander Max Stanley, co-pilot Fred Bretcher and flight engineer Orv Douglas.
After takeoff, the aircraft flew for a while at low altitude over the airbase with the landing gear extended at a speed of about 250 km / h. Then the chassis was retracted.
After the bomber gained an altitude of 2500 m with a climb rate of 3.8 m / s, it switched to horizontal flight at a speed of 265 km / h.
The first flight of the XB-35 lasted only 45 minutes, the maximum speed did not exceed 320 km / h. The planning speed for the landing approach is 200 km / h, the landing speed is 180 km / h. Having run about 900 m along the runway, the plane successfully completed its first flight.
A month later, a second flight took place, lasting 1 hour and 47 minutes, followed by others.
After the first successful sorties, the chief designer of the XB-35, John Northrop, based on preliminary results, stated that his aircraft has the following advantages over conventional aircraft of the same flight weight and with the same engines:
- increase in flight range by 25%;
- 25% increase in load at the same flight range and the same fuel reserve;
- increase in flight speed by 20% with the same engine power.
The XB-35 bomber also surpassed all American and British bombers that existed by that time in terms of the range / bomb load ratio, and was in no way inferior to them in other parameters.
If we compare the main characteristics of the XB-35 and its competitor B-36, which was later adopted instead of it for service, then the advantage of Northrop's "flying wing" is immediately apparent.
Judge for yourself:
- ХВ-35 - max. speed - 605 km / h, ceiling - 10,700 m, takeoff weight - 93,300 kg, flight range with a bomb load of 4,500 kg - 14,500 km. The propulsion system is four 3000 hp motors.
- B-36 - max. speed - 515 km / h, ceiling - 9150 m, takeoff weight - 136,000 kg, range with a bomb load of 4,500 kg - 13,000 km. The propulsion system consists of six 3500 hp motors.
However, a new era in the development of aviation began - jet, and Northrop, wanting to keep up with progress, developed a jet version of the XB-35 - YB-49.
The piston engines previously installed on the XB-35 aircraft were replaced by eight Allisson J35A-15 turbojet engines with a thrust of 1800 kg. The placement on the new car of such a number of engines - a whole battery of eight turbojet engines (four in two packages) was simply explained - there were no spent turbojet engines with high thrust.
Another feature of the new car was the installation of four keels, with which the designers tried to compensate for the lack of a stabilizing moment of the propellers. However, they turned out to be ineffective.
The installation of jet engines made it possible to significantly improve the flight characteristics of the aircraft: the takeoff weight decreased by more than five tons, the maximum speed increased by almost 300 km / h and reached 800 km / h, which was not bad at all for that time. No other bomber in the world has developed this speed.
The first flight, made from the factory airfield in Palmdale (California) with a landing at the US Air Force MurocArmy Air Field on October 21, 1947, was quite successful. Test pilot Max Stanley with the crew stayed in the air for 34 minutes in the new machine.
During the next flight on April 26, 1948, the bomber spent nine hours in the air, and for six hours the plane flew at an altitude of about 12,000 m. For this time, it was an outstanding achievement.
However, on one of the test flights on June 5, 1948, YB-49, piloted by pilot Captain Glenn Edwards, crashed.
The Air Force Commission, which investigated the causes of the tragic incident, concluded that it was himself to blame for the incident. When descending from an altitude of 12,000 m, the pilot switched the aircraft to an unacceptable mode, which caused heavy loads on the wing, as a result of which the XB-35 collapsed in the air.
Soon his name was given to the airbase, which later became the main air range of the US Air Force - Edwards.
This catastrophe seriously undermined the confidence of American generals in the new machine. An advertising campaign was urgently required to demonstrate the great potential of the aircraft.
Therefore, soon the jet bomber that remained in service, there were two of them, made another ultra-long-range flight from the Muroc Army Air Field to Washington. At the same time, he crossed the entire North American continent from west to east, showing an average speed of 822 km / h on a route length of 3630 km. The car was piloted by Major Robert Cardenas.
At Andrews airbase near Washington, the new jet bomber was examined by US President Harry Truman, who was impressed by the novelty. According to eyewitnesses, he even exclaimed: “Damn interesting plane! We need to order several of these machines. After the show, the Flying Wing went back to the west coast.
However, problems started on the way back. After making a stopover at Wright Field airbase near Dayton, the plane took off again.
And then the unexpected began. Almost simultaneously, three jet engines on the left and one on the right side caught fire. The crew, with the four remaining engines running, drove the car to Winslow Airfield in Arizona.
After replacing the burned out engines, the YB-49 went further to his home airbase. The exact cause of the fire could not be established.
The only remaining YB-49 was soon converted into a strategic photographic reconnaissance YRB-49A.
On October 28, 1949, all work on Northrop's "flying wings" was officially terminated. Although a year earlier, the company received a contract to complete the ten YB-49s that remained under construction in the workshops in the RB-35B reconnaissance version with six J-35-21 jet engines with a thrust of 2400 kg (four in the wing and two on the underwing pylons). Improvements after this decision were carried out on the only copy of the YB-49 that survived in the ranks.
On May 4, 1950, a reconnaissance aircraft piloted by Fred Bretcher and Dale Johnson took off for the first time. In a series of test flights that followed soon, the YRB-49A demonstrated good flight data - with a takeoff weight of 93,000 kg, the maximum speed was 885 km / h, and the flight range was 5630 km.
Not wanting to surrender, Northrop, in parallel with the tests of the scout, developed a program of improvements for the YRB-49A, not suspecting that the fate of the machine had already been decided. By this time, the US Air Force command had already finally decided to abandon such an extravagant machine. After a short discussion, the program for the development of the strategic reconnaissance aircraft "flying wing" YRB-49A was closed.
In the fall of 1953, the only flying machine in storage at Ontario Airport was disassembled. All B-35 and B-49 bombers, both completed and unfinished, were sent for scrap metal. It was ordered to forget about "flying wings".
For several reasons. Firstly, conservative American strategists preferred the B-36, which is inferior in most characteristics to the B-49, due to the fact that it was more in line with their views on a "normal" aircraft. Secondly, the compact bomb bays of the B-49 did not allow placing in them huge atomic bombs, and the delivery of conventional ammunition to the enemy's territory was considered irrelevant. And although it was obvious to far-sighted aviation specialists that compact nuclear weapons would soon be created, nothing depended on them.
Many aviation specialists in the early fifties considered the YB-49 to be a dead-end development branch with no future. This point of view became generally accepted, and it seemed to be the only correct one.
But life put everything in its place. When, shortly before his death, Northrop was shown the B-2 model, he said: "Now I know why God gave me the last quarter of a century of life."
The takeoff of the B-2 showed all the foresight and genius of the aircraft designer.
| Modification | YB-35 |
| Wingspan, m | 52.43 |
| Length, m | 16.18 |
| Height, m | 6.18 |
| Wing area, m2 | 371.60 |
| Weight, kg | |
| empty plane | 43284 |
| normal takeoff | 76340 |
| maximum takeoff | 102284 |
| engine's type | 2 PD Pratt Whitney R-4360-17 + 2 R-4360-21 Wasp Major |
| Power, h.p. | 2 x 3000 + 2 x 3000 |
| Maximum speed, km / h | 629 |
| Cruising speed, km / h | 294 |
| Practical range, km | 13113 |
| Maximum rate of climb, m / min | |
| Practical ceiling, m | 12100 |
| Crew | nine |
| Armament: |
3 turrets with four and 4 turrets with two 12.7-mm machine guns (1000 rounds each) Bomb load - 23245 kg maximum and 18700 kg normal |