Since the time of the Wright brothers, aviation engineers have experimented with the design of the “Flying Wing”: tailless aircraft with no definite fuselage. All components of the machine and the pilot itself are located in the plane of the wing. Theoretically, this is the most aerodynamic and efficient design of all. In practice, it turns out that without stabilization and features typical of an ordinary aircraft, such wings are very difficult to control.
Directly to the full-scale design of the XV-35, Northrop began its work in 1942, when the N-9M was just being prepared. Soon, two models of a future car with a wingspan of 2.44 m and 4.88 m, which went through a research program in a wind tunnel, were built ten times smaller.
Based on the successful results of the Northrop purging, it was decided to start building the first prototype bomber in January 1943.
The aviation world had not yet seen anything like it. The huge all-metal "flying wing" had a wing span of 52.42 m, height - 6.12 m, area - 371.6 m2.The mass of the empty aircraft was more than 40 tons, the maximum take-off weight was 95 tons, and the weight of the load reached 54.5 tons.
Four piston air-cooled Pratt and Whitney WaspMajor engines were installed in the front of the wing - two types of R-4360-17 and two types of R-4360-21 with a power of 3000 hp. each. All engines were equipped with General Electric turbochargers. The transfer from the internal engines to the four blades of the Hamilton Standart Supermatic with a diameter of 4.67 was carried out with a shaft of 7.2 m in length. From the external ones - 4.8 m. The protruding shaft shafts also improved the track stability of the machine.
To cool the machine units, slots were made in the front edge of the machine. Through which the air got into special pressure chambers located in the toe of the wing.
The complex construction of the bomber power plant units gave the developers a lot of problems: gearbox damage was constantly occurring, fires broke out, etc. All this threatened to crash an experienced car. Therefore, fine-tuning power units has become the main work of designers.
The chassis of the "flying wing" was a three-wheeled, retractable. The dual wheels of the main chassis had a diameter of 1.67 m, a single bow - 1.42 m.
Achieving the stability of the XB-35 in flight did not cause any particular difficulties.It was achieved by sweeping the wing and the selection of the appropriate profile, as well as a well-thought-out installation of the pushing screws behind the center of gravity of the aircraft.
Aircraft control was carried out by the shields, replacing the rudders, the usual “flying wings with elevons, as well as flaps and trimmers.
To improve the working conditions of pilots and facilitate piloting on the XV-35, hydraulic boosters were used. In addition to them, the aircraft was installed autopilot company "Minneapolis Honniell", designed specifically for this aircraft.
The crew of the XB-35 consisted of nine people: a pilot, a co-pilot, a scorer, a navigator, a flight engineer, a radio operator, and three gunners. If necessary, the crew could be increased to 15 people.
The mass of the bomb load when performing the task at a distance of 12,100 km was to be 4,500 kg.
To protect against enemy fighters, the bomber had powerful defensive armament: 12 Colt-Browning large-caliber machine guns and two automatic cannons. On the upper surface of the wing were installed two turrets with twin 12.7 mm machine guns, on the bottom - two turrets with quad 12.7 mm machine guns; in the rear of the aft installation - two 37 mm caliber guns.
The plane had practically no protruding parts, with the exception of the shafts of the shafts, the lantern of the pilot's cabin and the 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 machine. The Second World War had already ended, and the plane had never flown into the air.
The first prototype of the bomber was in the strictest secrecy delivered to the US Air ForceMuroc Army Air Field airbase for flight tests only in early May 1946, where the first taxiing began on May 16 at a speed of 50-65 km / h.
In early June, already made the first run on the lane 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 about a kilometer on the runway, the HV-35 smoothly lifted off the ground and went on its first flight. The crew included commander Max Stanley, co-pilot Fred Bretscher and flight engineer Orv Douglas.
After takeoff, the aircraft flew for a while at a low altitude above the airbase with the landing gear released at a speed of about 250 km / h. Then the chassis was removed.
After the bomber gained an altitude of 2500 m with a climb of 3.8 m / s, it went into horizontal flight at a speed of 265 km / h.
The first flight of the XV-35 lasted only 45 minutes, the maximum speed did not exceed 320 km / h. Planning speed during landing is 200 km / h, landing - 180 km / h. Having run about 900 m on the runway, the plane successfully completed its first flight.
A month later, there was a second flight lasting 1 hour 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 car has the following advantages compared with planes of the usual pattern of the same flight weight and with the same engines:
- increase the flight range by 25%;
- increase by 25% load with the same flight range and the same fuel stock;
- increase in flight speed by 20% with the same engine power.
The XB-35 bomber also outperformed all the American and British bombers that existed at that time in terms of the ratio “distance / bomb load”, 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, the advantage of the “flying wing” of Northrop is immediately apparent.
Judge for yourself:
- HV-35 - max. the speed is 605 km / h, the ceiling is 10,700 m, the take-off weight is 93300 kg, the range with a bomb load of 4500 kg is 14,500 km. The propulsion system - four motors of 3000 hp each.
- B-36 - max. the speed is 515 km / h, the ceiling is 9150 m, the take-off weight is 136,000 kg, the range with a bomb load of 4,500 kg is 13,000 km. The propulsion system - six motors with a capacity of 3,500 hp each.
However, a new era began in the development of aviation - jet, and Northrop, wanting to keep up with progress, developed a reactive version of the XB-35 - YB-49.
The piston engines installed earlier on the HV-35 aircraft replaced the Allisson eight turbojet engines with a 1800 kg bollard. Placing such a number of engines on the new machine - a whole battery of eight turbofan engines (four in two packages) was simply explained - there were no used heavy-duty turbojet engines.
Another feature of the new machine was the installation of four keels, the designers tried to compensate for the absence of the stabilizing torque of the screws. However, they proved ineffective.
The installation of jet engines made it possible to significantly improve the flight characteristics of the aircraft: the take-off weight dropped by more than five tons, the maximum speed increased by almost 300 km / h and reached 800 km / h, which was quite good for that time. No bomber in the world has developed such a speed.
The first flight, made from the factory airfield in Palmdale (California) with the landing at the US Air Force base MurocArmy Air Field on October 21, 1947, was quite successful. Test pilot Max Stanley with the crew spent 34 minutes in the air in a new car.
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 12000 m. For this time it was an outstanding achievement.
However, in one of the test flights on June 5, 1948, he crashed YB-49, piloted by pilot captain Glenn Edwards.
The Air Force Commission, which investigated the causes of the tragic incident, concluded that he himself was to blame for the incident. When descending from a height of 12,000 m, the pilot transferred the plane to an unacceptable mode, which caused heavy loads on the wing, with the result that the XB-35 fell apart in the air.
Soon his name was given to the airbase, which later became the main aviation ground of the US Air Force - Edwards.
This disaster has seriously undermined the confidence of American generals to the new machine. Urgently needed advertising campaign to demonstrate the great potential of the aircraft.
Therefore, soon the remaining jet bomber, there were two of them, made another ultra-long flight from the Muroc Army Air Field airbase 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 of 3,630 km. Piloted car major Robert Cárdenas.
At the Andrews airbase near Washington, a new jet bomber was examined by US President Harry Truman, who was greatly impressed by the novelty. According to eyewitnesses, he even exclaimed: “Damn interesting plane! There are several such machines to order. ” After the show, the “flying wing” headed back to the west coast.
However, problems started on the way back. Having made an intermediate landing at Wright Field airbase near the city of Dayton, the plane took off again.
And then the unforeseen began.Almost simultaneously, three jet engines on the left and one on the right side caught fire. The crew on the four remaining working engines drove the car to the Winslow airfield in Arizona.
After replacing the burned-out engines, the YB-49 went further to its native airbase. The exact cause of the fire could not be established.
The remaining single YB-49 was soon converted into a strategic photo reconnaissance YRB-49A.
October 28, 1949 all work on the "flying wings" Northrop were officially discontinued. Although a year earlier, the company received a contract to complete the construction of the remaining ten YB-49s in the workshops in the RB-35B variant with six J-35-21 jet engines of 2,400 kg (four in the wing and two on underwing pylons). Improvements after this decision were made on the only YB-49 instance preserved in the line.
On May 4, 1950, a reconnaissance aircraft piloted by Fred Bretcher and Dale Johnson took off for the first time. In the series of test flights that followed soon, the YRB-49A demonstrated good flight data - with a take-off weight of 93,000 kg, the maximum speed was 885 km / h, and the flight range was 5,630 km.
Not wanting to give up Northrop, in parallel with the tests of the scout, developed a program of improvements YRB-49A, unaware that the fate of the machine is already sealed.The command of the US Air Force at this point had already finally decided to abandon such an extravagant machine. After a brief discussion of the development program of the strategic intelligence "flying wing» YRB-49A was closed.
In the fall of 1953, the only flying machine in storage at the Ontario airport was dismantled. All the completed and unfinished B-35 and B-49 bombers were sent for scrap. The “flying wings” were ordered to be forgotten.
For several reasons. Firstly, conservative American strategists preferred the B-36, which is inferior in most of the B-49 indicators, due to the fact that it more closely corresponded to their views on the “normal” aircraft. Secondly, the B-49 compact bomb bay did not allow to place atomic bombs of enormous size in them, and the delivery of conventional ammunition to the enemy’s territory was considered irrelevant. And although it was obvious to farsighted aviation specialists that compact nuclear weapons would be created soon, but nothing depended on them.
Many aviation specialists of the early fifties considered the YB-49 to be a dead-end branch of development with no future. This view has become generally accepted, and it seemed the only true.
But life has put everything in its place. When, shortly before his death, the Model B-2 was demonstrated to Northrop, he said: "Now I know why the Lord has granted me the last quarter of a century of life."
The take-off of the B-2 showed all the foresight and genius of the aircraft designer.
|Wing area, m2||371.60|
|engine's type||2 PD Pratt Whitney R-4360-17 + 2 R-4360-21 Wasp Major|
|Power, hp||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|
3 turrets with four and 4 turrets with two 12.7-mm machine guns (1000 rounds each)
Bomb load - 23,245 kg maximum and 18,700 kg is normal </ p>