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OK, thank you Engineman. With your research and several responses to my inquiry, I believe we have sufficient information to create an intelligent exhibit sign to go with the propeller hub, spider, and governor cylinder parts we are cleaning up. After we finish cleaning and assembly, I'll post a picture of the display in our museum. ..... Larry
Hi Larry,
The earliest VP props that were adjustable pitch in flight were really the 2-position, coarse/fine type. The advantages of multi-pitch range adjustment rapidly followed, the
facilitating factor being primarily the design of operating controls and oil valves etc to achieve incremental adjustment. Further advances were to achieve the concept of variable
propeller (engine) speed control with pitch change and the critical factor here was the design of variable datum flyweight governor to suit, so becoming a Constant Speed system.
At the same time, the early VP props, like the counterweight H-S, were recognised for the small pitch range that did not fully suit high speed aircraft, nor did it facilitate full feathering for engine failure assistance in multi-engine types. The development of greater pitch-range VP props naturally followed.
The H-S counterweight type prop could have operated as a simple 2-position prop, but I suspect that it really fell into the adjustable multi-pitch type initially, rapidly being
adopted as a Constant Speed system.
The specific operation method depended on the aircraft installation. In the Battle of Britain, De Havilland licensed versions of the H-S counterweight prop operating in the
Constant Speed method were used by the British.
Many other detailed applications of the H-S counterweight prop existed.
Eng
A great summary but dH were actually licence building H-S counterweight props for the Blenheim as early as early 1936 and I think the Blenheim's forefather, the type 142, had dH counterweight props on its first flight in April 35.
All the early dH built H-S props were fitted to engines with two position controls such as the Merlin II thru V and the early Pegasus and Mercury as fitted to a number of aircraft up to and including the Blenheim Mk I, Lysander Mk I and Sunderland Mk I.
Thank you for the explanation, Eng. Now I better understand what was going on at the time.Hi Larry,
The earliest VP props that were adjustable pitch in flight were really the 2-position, coarse/fine type. The advantages of multi-pitch range adjustment rapidly followed, the
facilitating factor being primarily the design of operating controls and oil valves etc to achieve incremental adjustment. Further advances were to achieve the concept of variable
propeller (engine) speed control with pitch change and the critical factor here was the design of variable datum flyweight governor to suit, so becoming a Constant Speed system.
At the same time, the early VP props, like the counterweight H-S, were recognised for the small pitch range that did not fully suit high speed aircraft, nor did it facilitate full feathering for engine failure assistance in multi-engine types. The development of greater pitch-range VP props naturally followed.
The H-S counterweight type prop could have operated as a simple 2-position prop, but I suspect that it really fell into the adjustable multi-pitch type initially, rapidly being
adopted as a Constant Speed system.
The specific operation method depended on the aircraft installation. In the Battle of Britain, De Havilland licensed versions of the H-S counterweight prop operating in the
Constant Speed method were used by the British.
Many other detailed applications of the H-S counterweight prop existed.
Eng
Thank you for the explanation, Eng. Now I better understand what was going on at the time.
Larry