YB-40 Flying Fortress
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| YB-40 Flying Fortress | |
|---|---|
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| Type | Escort fighter |
| Manufacturer | Lockheed-Vega |
| Maiden flight | September 1942 |
| Introduced | 29 May 1943 |
| Retired | October 1943 |
| Primary user | United States Army Air Force |
| Number built | 25 |
| Developed from | B-17 Flying Fortress |
- This article is about the military aircraft. For the Vietnamese variant of the RPG-2 see B-40
The Boeing YB-40 Flying Fortress was a modification of the United States B-17 Flying Fortress bomber aircraft, converted to act as a heavily-armed escort for other bombers during World War II. At the time of its development, long-range fighter aircraft such as the P-51 Mustang were not yet available to accompany bombers all the way from England to Germany and back.
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[edit] Development
Work on the project began in September, 1942 with the XB-40 prototype, built by Lockheed's Vega subsidiary. The first order of 13 was made in October 1942. A follow-up order for 12 more was made in January, 1943. The modifications were performed by Douglas Aircraft at their Tulsa, Oklahoma center, and the first aircraft were completed by the end of March, 1943.
The aircraft differed from the standard B-17 in that a second dorsal turret was installed in the former radio compartment, just behind the bomb bay and forward of the ventral ball turret's location; the single 0.50-calibre (12.7 mm) Browning machine gun at each waist station was replaced by a pair of similar 0.50-calibre (12.7 mm) guns, with a mount for each pair of these being very much like the tail gun setup in general appearance; and the bombardier's equipment was replaced with two 0.50-calibre (12.7 mm) machine guns in a Bendix designed "chin" turret. The existing "cheek" machine guns (on the sides of the forward fuselage at the bombardier station), initially removed from the configuration, were restored in England to provide a total of sixteen guns, and the bomb bay was converted to an ammunition magazine. Additional armor plating was installed to protect crew positions. The aircraft's gross weight was some 4000 pounds greater than a fully-armed B-17. An indication of the burden this placed on the YB-40 is that while the B-17F on which it was based was rated to climb to 20,000 feet in 25 minutes, the YB-40 was rated at 48 minutes. Part of the decreased performance was due to the weight increase, and part was due to the greater aerodynamic drag of the gun stations.
[edit] Operational history
The YB-40's mission was to provide a heavily-gunned escort capable of accompanying the bombers all the way to the target and back. Overall the concept proved a failure because the YB-40 could not keep up with standard B-17Fs, particularly after they had dropped their bombs. Of the initial order of 13, one was damaged in a forced landing on the Isle of Lewis en route to England, and the remaining 12 were assigned to the 92nd Bomb Group (H) and designated the 327th Bomb Squadron.
Between May 29 and August 16, 1943, the YB-40 flew 14 of the 19 combat missions scheduled by the 8th Air Force, although on the mission of June 26 all the YB-40s scheduled were unable to form up with the bombing squadron, and returned to base. Altogether of the 59 aircraft dispatched, 48 sorties were credited. Five German fighter kills and 2 probables (likely kills) were claimed on the 13 missions flown, and one YB-40 was lost, shot down by flak on the June 22 mission to Hüls, Germany. Tactics were revised on the final five missions by placing a pair of YB-40s in the lead element of the strike to protect the mission commander.
One YB-40 of the second order, reflecting modifications requested during combat trials to lighten the aircraft, joined the 327th in October, 1943, but by then B-17G models were beginning to appear and the final YB-40 was not flown in combat. All the deployed YB-40s were returned to the United States and converted to training aircraft, as were 11 aircraft of the second order.
One of the most unusual stories involving the use of a YB-40 was to counter the efforts of an Italian pilot, Guido Rossi, who had begun to offensively fly a captured P-38 Lightning fighter that had been forced to land, low on fuel, over Sardinia in the spring of 1943. Rossi used the P-38 as a supposedly "friendly" aircraft to first draw in, then shoot down, crippled American aircraft. Lt. Harold Fisher, a USAAF bomber pilot who had been victimized by Rossi's still-American-marked P-38, was able to get the use of a YB-40 to try and turn the tables on the Italian pilot. On August 31, 1943, Rossi appeared in the sky in the general vicinity of the YB-40, and Fisher drew Rossi in with radio conversation. Eventually the Italian pilot became furious at one of Fisher's statements, and the attacking P-38 fell apart from the hail of bullets from the YB-40's guns. This event was documented in the pages of aviation author Martin Caidin's book "Flying Forts", about B-17 action in WW II Europe.[1],[2]
Despite the failure of the project as an operational aircraft, it led directly to modifications conspicuous on the final production variant of the B-17, the B-17G:
- Chin turret
- Offset waist gun positions
- Improved tail gunner station.
[edit] Operators
[edit] Specifications (YB-40)
General characteristics
- Crew: 10
- Length: 74 ft 4 in (22.7 m)
- Wingspan: 103 ft 10 in (31.6 m)
- Height: 19 ft 1 in (5.8 m)
- Wing area: 1,527 ft² (141.9 m²)
- Empty weight: 54,900 lb (24,900 kg)
- Loaded weight: 72,134 lb (32,720 kg)
- Max takeoff weight: 74,000 lb (34,000 kg)
- Powerplant: 4× Wright R-1820-65 turbosupercharged radial engines, 1,200 hp (895 kW) each
Performance
- Maximum speed: 292 mph (470 km/h)
- Cruise speed: 196 mph (315 km/h)
- Range: 2,260 mi (3,640 km)
- Service ceiling 29,200 ft (8,900 m)
- Rate of climb: ft/min (m/s)
- Wing loading: 47.2 lb/ft² (231 kg/m²)
- Power/mass: 0.066 hp/lb (0.11 kW/kg)
Armament
- Guns: 14 (or more) × .50 in (12.7 mm) Browning M2 machine guns. Typically used 14-16, with room for up to 30.
| Location | Rounds |
| Nose | 2200 |
| Front top turret | 2500 |
| Aft top turret | 3300 |
| Ball turret | 300 |
| Waist guns | 1200 |
| Tail guns | 1200 |
| Total | 10,700 |
[edit] References
- Freeman, Roger A. (1990). The Mighty Eighth War Diary. ISBN 0-87938-495-6.
- Freeman, Roger A. (1991). The Mighty Eighth War Manual, 154-155. ISBN 0-87938-513-8.
- Bishop, Cliff T. (1986). Fortresses of the Big Triangle First, 69, 73, 246-247. ISBN 1-869987-00-4.
- Encyclopedia of American Aircraft
- USAF Museum article on YB-40
[edit] External links
[edit] See also
Related development
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