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When one thinks of “fighters,” one traditionally thinks of relatively small, high-speed aircraft with great agility and maneuverability. But in mid-1943, when the Army Air Force was attempting to mount a daylight bombing offensive into Germany, these attributes paled in significance in comparison to one other requirement – long range.
***image1***Early in World War II, both the Royal Air Force and the German Luftwaffe had tried
unescorted daylight bombing raids, but both had suffered so many losses they quickly gave up and switched to night raids.
Nevertheless, in 1942 the AAF’s 8th Air Force had begun a daylight bombing campaign from England based on its prewar doctrine that formations of its seemingly heavily-armed B-17 and B-24 bombers would be able to penetrate enemy airspace for precision attacks on critical industries that would destroy the enemy’s capability to resist.
The German fighter force quickly shot this idea to pieces and by early 1943, heavy B-17 and B-24 losses made it clear that the American bombers needed some sort of fighter protection all the way to the target and back. But there was a problem: The United States – like every other country except Japan – lacked a fighter that had the range to accompany the bombers deep into Germany and the performance to defeat enemy fighters.
This emergency generated a number of programs to provide an escort aircraft, but one that could be implemented fairly quickly and easily was to simply modify a B-17F to a fighter by mounting much heavier armament and letting it fly in formation with the B-17 bombers. The “fighter Fortress” was dubbed the YB-40 (the Y stood for “service test”) and was developed by Lockheed’s Vega subsidiary.
The YB-40 differed from the standard B-17F by having a second top turret installed in the former radio compartment just behind the bomb bay, changing the single waist 0.50-caliber gun to a pair of similar guns, and replacing the bombardier’s equipment with two 0.50-calibre (12.7 mm) machine guns in a Bendix designed “chin” turret.
The bomb bay was converted to an ammunition magazine with 17,265 rounds of ammunition, and additional armor plating was installed to protect crew positions. The YB-40s carried a total of 16 guns, 10 in enclosed power turrets, instead of the standard B-17F’s nine guns with six in powered turrets. The YB-40s began to arrive in England in May 1943 and 12 were assigned to the 327th Squadron of the 92nd Bomb Group, 8th Air Force. The first operational YB-40 sortie took place May 29, 1943 against St. Nazaire, France.
Very early in the YB-40s operations, it was found that, even with the reduction in weight without the bombs, the YB-40’s gross weight was 4,000 pounds greater than a fully-armed B-17. This extra weight, combined with the greater aerodynamic drag of the gun turrents, resulted in a concomitant decrease in performance. A standard B-17F could climb to 20,000 feet in 25 minutes, but the YB-40 took 48 minutes. Additionally, the net effect of the changes reduced the speed of the YB-40 to a point where it could not maintain formation with the standard B-17s on the way home from the target once they had released their bombs.
Between May 29 and Aug. 16, 1943, YB-40s flew on 14 of the 19 raids scheduled by the 8th Air Force. Altogether, the YB-40s flew 59 sorties – 48 sorties effective – and claimed five kills and two probables. One YB-40 was lost, shot down by flak on the June 22 mission to Hüls, Germany.
The final blow to the program took place on June 26 when all the YB-40s scheduled were too slow to form up with the bombing squadrons and returned to base. By the end of July, it was recognized that the YB-40 project was an operational failure and they were withdrawn from service in late July 1943.
But the YB-40 did have a lasting impact on Air Force history. The chin turret originally introduced on the YB-40 was later adopted as standard for the B-17G series and helped solve the German head-on attacks. But perhaps more famously, on July 26, 1943, a YB-40 pilot received a head wound during a fighter attack and the copilot, John C. Morgan, flew the plane in formation with one hand while restraining the struggling pilot for two hours until another crewman arrived. Morgan was awarded the Medal of Honor, and this action incident was immortalized in the movie “Twelve O’clock High!” when Morgan became Lt. Jessie Bishop.
