North American XB-28
| North American XB-28 | |
|---|---|
 North American XB-28 with the engines running |
|
| Type: | bomber |
| Design country: | |
| Manufacturer: | |
| First flight: |
April 26, 1942 |
| Commissioning: |
Never put into service |
| Production time: |
Was never mass-produced |
| Number of pieces: |
2 |
The North American XB-28 (model NA-63 and NA-67) was developed by North American Aviation as a medium-weight high-altitude bomber in the early 1940s . Only two planes were built.
Development history
The order for the development and construction of three prototypes of the model originally planned as a high-altitude version of the B-25 Mitchell was placed on February 13, 1940. During the development of the aircraft, the design got a completely new design, which was very reminiscent of the Martin B-26 Marauder . The round fuselage with a pressurized cabin for five crew members and the simple tail unit at the stern are the biggest differences to the B-25.
The XB-28 was powered by two powerful Pratt & Whitney R-2800-11 with turbochargers, which delivered an output of 1,491 kW (2,000 hp). The drive helped the XB-28 to a top speed of 446 km / h at a height of 7620 m.
As defensive armament, remote-controlled defense towers were provided at the stern, which were attached to the back of the fuselage and to the fuselage floor. They each had two machine guns with a caliber of 12.7 mm and were remotely operated by a shooter sitting behind the pilot. The alignment of the MGs was done through a periscope system. Two to three 12.7 mm machine guns were provided for forward defense. As a dropping ammunition up to 2722 kg (6000 pounds) were planned, which should be transported over a distance of 3280 km (2040 miles).
The first flight of the XB-28 (40-3056, c / n 63-2233) took place on April 26, 1942 (other sources cite April 24) with test pilot Edward Virgin on board. Although the performance of the XB-28 was much better than that of the B-25, it did not go into series production. The B-25 and B-26 were already in mass production and the A-26 was in development. Bombarding targets from great heights could not be very accurate because cloud formation and winds made aiming difficult.
The USAAF rejected the XB-28 as a bomber and the order for the second prototype was withdrawn, which was then no longer completed. A third prototype as the XB-28A with the in-house designation NA-67 (40-3058, c / n 67-3417) was completed as an altitude reconnaissance and research aircraft, which again had its maiden flight on August 4, 1943 with Edward Virgin on board. Two Pratt & Whitney R-2800-27s were used for propulsion and the aircraft was unarmed. After the machine crashed during roll rate tests by test pilots Bob Chilton and Roy Ferris as a result of strong pendulum movements of the rudder pedal and subsequent loss of control, it was written off on August 4, 1943 and the program was discontinued. The two pilots were able to jump off in the accident and were rescued unharmed. The fuselage of the first prototype was used by the USAAF as a high-pressure chamber after the end of flight tests.
Technical specifications
| Parameter | Data |
|---|---|
| Type: | five-seat high-altitude bomber |
| First flight: | April 26, 1942 |
| Manufacturer: | North American Aviation |
| Engines: | two Pratt & Whitney R-2800-11 with 1,491 kW |
| Empty mass: | 11,600 kg |
| Takeoff mass: | 16,210 kg |
| Maximum takeoff mass: | 17,728 kg |
| Span: | 22.12 m |
| Wing: | 62.80 m² |
| Length: | 17.18 m |
| Height: | 6.69 m |
| Top speed: | 599 km / h at an altitude of 7,620 m |
| Marching speed: | 410 km / h |
| Range: | 3,280 km (with 270 kg bomb load) |
| Service ceiling: | 10,213 m |
| Climb rate: | 610 m / min |
| Wing loading: | 258.14 kg / m² |
Web links
Individual evidence
- ↑ according to Aero 123 - p. 3488 it was 599 km / h in 7620 m
- ↑ after Aero 123 - p. 3488
- ↑ to http://www.joebaugher.com/usaf_bombers/b28.html but according to Aero 123 - p. 3488 it should have been 1814 kg (4000 pounds).
- ↑ according to Aero 123 - p. 3488 , 272 kg should be transported over the 3283 km, which of course represents a completely different value.
- ↑ a b FlugRevue August 2010, pp. 92–95, XB-28 - Flying high without a chance
- ↑ see the production program of the USA: ARMY AIR FORCE STATISTICAL DIGEST table 85