lo mismo os digo que con el glosario, aun no me ha dado tiempo a traducir, y tambien sacado del jane's, tipos de hélices:
First and simplest of the propeller types is fixed-pitch, constructed of carved wood (normally glued multiple-ply for warp resistance), wood with composites skin, or aluminium. Pitch is blade angle in respect to a flat plane; proportional to the distance the propeller will advance through the air on each rotation. Fine pitch - a small angle - allows a low-power engine to develop a high rotational speed, but delivers low forward airspeed. Coarse pitch is optimised for higher speeds, but requires proportional engine power.
While diameter and blade area are related factors in performance, as is the subtle change of pitch along the blade's length, fixed-pitch is, by definition, a compromise made at the time of manufacture. Light aircraft options are normally restricted to the operator's choice of a fine-pitch 'climb propeller' or coarse-pitch'cruise propeller', according to operating environment and preference.
Increasingly, light aircraft have a ground-adjustable pitch propeller. Blades are mounted in sockets in the hub and clamped in place by a bolt. In theory, the pitch can be re-set to meet the specifics of each flight, but it is more normal for the owner to experiment with blade angles until the optimum for the aircraft is reached. Wood and wood/composites are used in construction, as is carbon fibre.
For special applications, such as motor gliders, a fixed-pitch, but folding propeller offers the simplest means of eliminating propeller drag in engine-off models. The propeller is at rest in a folded position (blades either parallel to the axis of motion or at right-angles to it, held in place by spring or bungee rubber) and extends when engine torque is applied
Variable pitch enables fine pitch to be used to enhance take-off and initial climb performance (maximum engine power at low airspeed), before a change to coarse pitch for fastest cruising speed without overspeeding the engine. Before and during landing, fine pitch and a low throttle setting will have the effect of increasing drag. Several methods of variable pitch are available:
Two-position: The propeller is pre-set in fine pitch for take-off and the pilot provided with a once-only means of reverting to coarse pitch. Rare in current usage.
Automatic pitch: Automatic alteration of pitch angle according to airspeed, often indicated by a vaned spinner ahead of the propeller. Rare in current usage.
Flight-adjustable pitch: Change controlled manually by the pilot and constantly monitored for each stage of flight, in concert with selected engine power. Electric or hydraulic actuation. The term 'variable pitch' is often used, loosely, to describe flight-adjustable pitch.
Constant-speed: A governor (constant-speed unit) is set by the pilot to the desired engine (and propeller) speed and pitch is constantly and automatically altered to maintain the desired value. Throttle changes (in fact, manifold pressure variations) can then be made by the pilot without reference to the propeller, which will adjust to the correct setting. However, the setting is changed manually for each stage of the flight (take-off, climb and cruise).
The availability of flight-adjustable and constant-speed mechanisms permits two further options:
Feathering: Blade pitch can be extended to neutral (edge-on to the airflow), reducing drag upon engine failure, or when deliberately gliding. The propeller may'windmill' (turn slowly on account of residual pitch).
Reverse pitch: Change of pitch beyond feathering angle to produce forward thrust for more rapid stopping or ground and water manoeuvring.