|
|
The Boston II was the British designation for late production French DB-7s, powered by the Pratt & Whitney R-1830-S3C4-G Twin Wasp with a two-speed supercharger. These aircraft reached Britain between the late summer of 1940 and early 1941. Once they had been modified to British standards most of them were converted to serve as night fighters, with the designation Havoc I.
The DB-7 was a significantly less powerful aircraft than the British ordered DB-7B, which would become the Boston III. The French aircraft had a combat range of under 500 miles, compared to the 745 miles of the Boston III, and its Twin Wasp engines produced 2,200ph, while the Double Cyclones of the Boston III put out 3,200hp. However the French DB-7 was lighter than the British aircraft, so it was only 30mph slower than the Boston III.
No two sources agree on the number of Boston IIs received, almost certainly because of the confusion caused by the repeated changes of designations that followed. 132 serial numbers would seem to have been used on Havoc Is, out of 181 available. Other sources give a total of 125 aircraft. The upper limit would appear to be 149 aircraft, for all of the Boston IIs came from the original French order for the DB-7, of which 121 were accepted by the French (although sixteen of these then found their way to Britain in the colours of the Belgian Air Force, where they became Boston Is). The limit may be lower, for the first 30 or so of the 170 DB-7s ordered with the R-1830-S3C4-G engine actually used that engine.