comic strip The YB-40's mission was to provide a heavily armed escort capable of accompanying bombers all the way to the target and back. Of the initial order of 13, one (serial 43-5732) was lost on the delivery flight from
Iceland to the UK in May 1943; it force-landed in a
peat bog on a Scottish island after running out of fuel. Although removed to
Stornoway and repaired, it never flew in combat. The remaining 12 were allocated to the
92d Bombardment Group (Heavy), being assigned to the
327th Bombardment Squadron, stationed at
RAF Alconbury (AAF-102) on 8 May 1943. YB-40s flew in the following operational missions: • 29 May 1943 – attacked
submarine pens and locks at
Saint-Nazaire. Smaller strikes were made at
Rennes naval depot and
U-boat yards at
La Pallice. In the attack, seven YB-40s were dispatched to Saint-Nazaire; they were unable to keep up with B-17s on their return from the target and modification of the waist and tail gun feeds and ammunition supplies was found to be needed. The YB-40s were sent to Technical Service Command at the
Abbots Ripton 2nd Strategic Air Depot for modifications. • 15 June 1943 – four YB-40s were dispatched from Alconbury in a raid on
Le Mans after completion of additional modifications. • 22 June 1943 – attack on the
I.G. Farben synthetic rubber plant at
Hüls. The plant, representing a large percentage of the Germany's synthetic rubber producing capacity, was severely damaged. In the raid, 11 YB-40s were dispatched; aircraft 42-5735 was lost, being first damaged by
flak and later shot down by a
Focke-Wulf Fw 190A-2 of
JG 1 over
Pont, Germany. The 10 crew members survived and were taken prisoner. • 25 June 1943 – attack on
Blohm & Voss U-boat machine shops at
Oldenburg. This was the secondary target, as the primary at
Hamburg was obscured by clouds. In this raid, seven YB-40s were dispatched, of which two aborted. Two German aircraft were claimed as destroyed. • 26 June 1943 – scheduled but aborted participation in attack on the
Luftwaffe air depot at
Villacoublay, France (primary target) and also the
Luftwaffe airfield at
Poissy, France. The five YB-40s assigned to the attack were unable to form up with the bombing squadron, and returned to base. • 28 June 1943 – attack on the U-boat pens at Saint-Nazaire. In the raid, the only serviceable lock entrance to the pens was destroyed. In this attack, six YB-40s were dispatched, and one German aircraft was claimed as destroyed. • 29 June 1943 – scheduled participation in attack on the
Luftwaffe air depot at Villacoublay, but aircraft returned to Alconbury due to clouds obscuring the target. In the raid, two YB-40s dispatched, one aborted. • 4 July 1943 – attacks on aircraft factories at
Nantes and Le Mans, France. In these raids, two YB-40s were dispatched to Nantes and one to Le Mans. • 10 July 1943 – attack on
Caen/
Carpiquet airfield. In this raid, five YB-40s were dispatched. • 14 July 1943 – attacked
Luftwaffe air depot at Villacoublay. In this raid, five YB-40s were dispatched. • 17 July 1943 – YB-40s recalled from a raid on
Hannover due to bad weather. In this raid, two YB-40s were dispatched. • 24 July 1943 – YB-40s recalled from an attack on
Bergen,
Norway due to cloud cover. In this raid, one YB-40 was dispatched. • 28 July 1943 – attack on the
Fieseler aircraft factory at
Kassel. In this raid, two YB-40s were dispatched. • 29 July 1943 – attack on U-boat yards at
Kiel. In this raid, two YB-40s were dispatched.
Summary Altogether of the 59 aircraft dispatched, 48
sorties were credited. Five confirmed and two probable German fighter kills were claimed, and one YB-40 was lost, shot down on 22 June 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. The original design concept of the YB-40 never played out as intended in practice. Luftwaffe fighter chief
Adolf Galland considered the gunship's handful of combat victories to be "insignificant" and not worth the cost of the aircraft. The increased weight from the additional machine guns and ammunition nearly cut the YB-40's climb rate in half from that of a B-17F, and in level flight it had difficulty keeping up with standard Flying Fortresses, especially after they had dropped their bombs. Despite the overall failure of the project as an operational aircraft, it led directly to the Bendix chin turret's fitment on the last 65 (86 according to some sources) Douglas-built aircraft starting with the B-17F-70-DL production block, and were part of the standardized modifications conspicuous on the final production variant of the B-17, the
B-17G: • Chin turret (first introduced on the last 86 Douglas-built "final production" blocks of the B-17F-DL aircraft) • Offset waist gun positions • Improved tail gunner station with much larger windows, usually nicknamed the "Cheyenne", after the
Cheyenne Modification Center. Once the test program ended, most of the surviving aircraft returned to the U.S. in November 1943 and were used as trainers. 42-5736 ("Tampa Tornado") was flown to
RAF Kimbolton on 2 October 1943 where it was put on display and later used as a group transport. It was returned to the United States on 28 March 1944. All of the aircraft were sent to reclamation, mostly at
RFC Ontario in May 1945, being broken up and smelted. A couple of the YB-40s can be seen in the 1946 movie
The Best Years of Our Lives, in the famous scene shot at the Ontario "graveyard". No airframes were sold on the civil market. ==Operators==