The Lockheed Hudson Mk.III was a significant improvement on the earlier versions of the aircraft. One serious problem with the Hudson Mk.I was its limited defensive firepower. In an attempt to solve this problem the Mk.III was given three extra .303in machine guns, one in a retractable ventral position and two in beam positions, giving it a total of seven guns and removing a blind spot below the aircraft.
The Mk.III was given more powerful Wright R-1820-G205A engines, providing 1,200hp at take-off and 1,050hp at 7,500ft, powering Hamiltan constant speed propellers. The Mk.III also featured the stronger fuselage of the Mk.II. Lockheed designated the Mk.III as the Model 414.
A total of 428 Mk.IIIs were built before the start of lend-lease. Of these 241 were given extra fuel tanks in the wings, and given the designation Mk.III(LR), while the earlier aircraft became the Mk.III(SR). 371 of these aircraft served with the RAF, 54 with the RNZAF and 3 with the RCAF.
Lockheed Hudson Mk.IIIA
After the lend-lease agreement came into force the Hudson received official USAAF designations. The exact equivalent of the Hudson Mk.III (LR) was the A-29-LO. This was powered by the Wright R-1820-87 nine-cylinder radial engine, the military designation for the 1,200hp G205A. A total of 416 were built, serving with seven armed forces in six countries. The largest number went to the USAAF (153), followed by the RCAF (133), the RAAF (41), the RAF (32), the Chinese Air Force (23), the US Navy (20, as the PBO-1) and the RNZAF (14).
Another 384 aircraft were built as the A-29A-LO. These were very similar to the A-29-LO, but featured a convertible interior which could easily swap between carrying bombs or troops. A total of 384 A-29As were built, bringing the total of Hudson Mk.IIIAs up to 800. This time the RAF was the main recipient, getting 289 aircraft, followed by the RAAF (65), RNZAF (23), RCAF (4) and the Chinese Air Force (3).
With a total of 1,228 built the Hudson Mk.III/IIIA was the most common version of the aircraft.