[tcolvin]

I would say operations were carried out at a cruising speed of 167 mph. This translated into an average speed over the ground for an entire sortie from take off to touch down of 136 mph. I base this on a sortie to drop sea-mines under the Tirpitz in the Wilhelmshaven Bauhafen that was aborted because of intense Flak.

P4340 of 61 Squadron, with F/Sgt Saunders, Sgt Hollidge, Sgt Flanigan and Sgt Hewitt took off from Hemswell at 22.06 on July 20, 1940, flew to Wilhelmshaven at an unrecorded height, offloaded their bombs onto ships off the mole at a low height, returned at an unrecorded height, and landed at Hemswell at 0315 on July 21.
Bomb-load not given but guessed at 3,000 lb.
Distance was 350 miles point-to-point: 700 miles round-trip
Time taken: 5 hrs 9 minutes, or 5.15 hrs
Calculated average speed: 136 mph

Performance data for the Hampden:
Weights; empty 11,780 lb; normal loaded 18,756 lb, maximum permissible 21,000 lb.
Maximum speed; 265 mph at 15,500 ft at normal loaded weight of 18,756 lb
Maximum cruising speed: 217 mph at 15,000 ft
Economical cruising speed: 167 mph at 15,000 ft
Service ceiling; 22,700 ft