Ground-adjustable propeller

A ground-adjustable propeller is a simple type of variable-pitch aircraft propeller, (aka controllable pitch propeller), whose blades can be rotated around their long axis to change their pitch, but in this instance any adjustment can be performed only on the ground. Ground-adjustable propellers are much cheaper than in-flight-adjustable propellers, and are found on light aircraft and very light aircraft.

Whereas a fixed-pitch propeller is the equivalent to a gearbox with a single gear ratio, a variable-pitch propeller may be compared to a gearbox whose ratios are infinitely variable between its two limits. Fine pitch ("bottom gear") is selected for take-off, climb and landing, and coarse pitch ("top gear") for cruise speeds. Although a ground-adjustable propeller cannot be adjusted whilst in flight, it still has advantages over a fixed-pitch propeller, in that the pilot may, when on the ground, select between finer and coarser pitches to suit conditions of the proposed flight, as follows:

• Conditions where a coarser pitch may be selected:

Aircraft in prime condition, a long runway, hard dry ground, cool dense dry air, a strong headwind, low altitude, & light payload*.

• Conditions where a finer pitch should be selected:

Aircraft in "tired" condition, a short runway, soft wet ground, long or wet grass, still hot thin moist air, high altitude, & heavy payload*.

( Payload is the combined weight of pilots, passengers, fuel & cargo).

Applications

• Arplast EcoProp^[1]
• Warp Drive Inc^[2]
• Woodcomp^[3]
• Ivoprop^[4]

References