Northrop YB-35
| Northrop YB-35 | |
|---|---|
 XB-35 during a test flight |
|
| Type: | Prototype of a strategic bomber |
| Design country: | |
| Manufacturer: | |
| First flight: |
June 1946 |
| Commissioning: |
Flight tests ended in 1949 |
| Production time: |
Was never mass-produced |
| Number of pieces: |
11 |
The Northrop YB-35 was (Northrop NS-9) an American heavy bomber in flying wing construction method. The experimental aircraft was developed during and shortly after the Second World War for the then United States Army Air Forces (now the United States Air Force ). In this design, the horizontal stabilizer is integrated into the wing. Although only prototypes and pre-series aircraft were built, interest in flying wing aircraft remained strong and it was decided before the first flight to convert three of the aircraft to Northrop YB-49 jet aircraft ; however, a later order for RB-49 reconnaissance aircraft was canceled due to technical concerns. It was not until decades later that the Northrop Corporation realized flying wing technology in series production with the Northrop B-2 .
development
The B-35 was Jack Northrop's personal favorite . Northrop focused its work as early as the 1930s on flying wings, as they theoretically with less resistance to flow more buoyancy promised. For the B-35 this meant that it could carry more payload further, faster and cheaper than a conventional bomber.
On April 11, 1941, the United States Army Air Corps launched a tender for a bomber with a 4.5 ton bomb payload and a range of 16,090 kilometers, at a maximum speed of 833 km / h or cruising speed of 500 km / h. The service ceiling should be approximately 14 kilometers (45,000 ft ). This aircraft should be able to continue bombing targets in Europe if Britain were to surrender to Germany. Initially, the competition took place between Boeing and Consolidated Vultee Aircraft Corporation , shortly after the start of the tender, Northrop was also involved and a design was requested. The Convair B-36 emerged from the competition .
To verify the flight characteristics, a 1: 3 scale model was built ( Northrop N-9M ). With this model the first data were collected, whereupon the development of the XB-35 began.
variants
XB-35
On November 22, 1941, the Army Air Corps signed the development contract for an XB-35. In the treaty there was an option for a second aircraft, which was considered on January 2, 1942. The first XB-35 was to be delivered in November 1943, the second in April 1944.
Assembly began at the beginning of 1942. The pilot's cabin was integrated into the wing, and another conical cabin protruded from the rear edge of the wing. In the production model, a camera was to be installed there, which should enable the gunner of the on-board MGs to see the area behind the aircraft. In the rear part of the cabin there was sleeping space for the crew when deployed over long distances.
An additional delay in the program resulted from the instruction to also build a variant with jet propulsion and, more generally, due to a downgrade to a mere research program, when it became apparent that the war would be over before it could be used. The XB-35 first took off in June 1946, flying from Northrop's Hawthorne, California, facility to Dry Lake in 45 minutes . The difficulties with the gearbox of the counter-rotating propellers during this flight were the first harbingers of problems to come. Both XB-35s were shut down after just a few flights. Even so, the YB-35 program continued as planned.
YB-35
On September 30, 1943, the Army Air Force ordered 13 pre-production models. When the first of these aircraft took off on May 15, 1948, it was already evident that the propeller-driven B-35 was outdated compared to the new jet-powered aircraft. The independent US Air Force ( US Air Force ), which was founded at the time, did not want to stop the expensive program without any benefit. That is why there were brain teasers to use the B-35 as a reconnaissance aircraft or a tanker . However, the unstable attitude prevented these uses.
Only the first YB-35 flew on May 15, 1948, and the tests then only lasted a few months. In August 1949, the first two aircraft were scrapped. Two had jet engines and had been renamed Northrop YB-49 . Another four of the pre-production models were cannibalized as spare parts, these were given the name YB-35B . The last five of the YB-35s have been upgraded, named YB-35A . Of these, a machine equipped with six jet engines was renamed the YRB-49A . Another, later EB-35B , was used as a test platform for the turboprop - engines of type XT-37 Turbodyne. The aircraft was scrapped in March 1950. The other three YB-35A later also became the spare parts store with the pattern designation YB-35B.
The USAF took over the following aircraft: 1 XB-35 in 1948, 1 XB-35 in the first quarter of 1949, 1 YB-35 in 1948 and 5 YB-35 and 5 YB-35A in the first quarter of 1949, a total of 13 aircraft. Of the 13 YB-35s ordered, two were delivered directly as YB-49s: one in June 1948 and one in the first quarter of 1949.
Setbacks
The Air Force originally ordered 200 models of the B-35. However, since Northrop's factories did not have the capacity for this, the Glenn L. Martin Company agreed to take over production, but the delivery date was postponed from 1944 to 1947 due to a shortage of workers during the war. Since the postponement made intervention in the war unlikely and the competition was already working on jet bombers, the program was continued as a test program.
The setbacks began when testing the model, the N-9M. These suggested that the required range of 16,093 kilometers would probably be undercut by around 2,600 kilometers, and the speed also seemed insufficient. In addition, there were miserable flight characteristics. The counter-rotating propellers of the XB-35 caused additional frequent gearbox malfunctions.
The first XB-35 was therefore shut down after only 19 flights and the second after eight flights. At that time, the counter-rotating propellers were exchanged for conventional ones, which, however, caused vibrations and further reduced the aircraft's performance. The complicated exhaust system was also a headache as it was difficult to maintain. After only two years, material fatigue was found on the engines .
Ultimately, the program failed due to its endless technical difficulties, the obsolescence of the propeller engines and the unstable flight attitude, which reduced the suitability as a bomber. Despite these obvious flaws, there have been numerous conspiracy theories surrounding the termination of the program. In view of the aircraft's shortcomings, these appear unlikely, as the B-35 was unsuitable as a platform for atomic bombs. In addition, Northrop was commissioned to build the F-89 Scorpion at this time .
Technical specifications
| Parameter | Data |
|---|---|
| crew | 9 (pilot, copilot, bombardier, navigator, mechanic, radio operator, three shooters) |
| length | 16.2 m |
| span | 52.2 m |
| height | 6.2 m |
| Wing | 370 m² |
| Surface thickness | 2.9 m |
| Empty mass | 54,432 kg |
| loaded | 82,000 kg |
| Max. Takeoff mass | 95,000 kg |
| Top speed | 629 km / h |
| Range | 13,100 km |
| Service ceiling | 12,100 m |
| Rate of climb | 190 m / min |
| Engine | 2 × Pratt & Whitney R-4360 -17 and 2 × R-4360-21, each 2240 kW (3000 PS) |
| Thrust / mass ratio | ? |
| Armament |
|
See also
Web links
Individual evidence
- ^ A b c Philip Kaplan: Big Wings: The Largest Airplanes Ever Built. Pen and Sword 2005, ISBN 978-1-84415-178-3 , p. 65.
- ↑ Statistical Digest of the USAF: 1948II, p. 17; 1949, p. 164
- ↑ 1946-1949 - Flying wings , Mashable