Power setting determines whether the helicopter will
~ stay in level flight
~ descend, or
~ climb
at the particular attitude the pilot has chosen.

When >attitude flying helicopter
~ large power changes do influence speed, and
~ some compensation of attitude needs to be made for gross changes in power settings

Pilots can quickly learn
~ what attitudes will command a certain airspeed
~ what power settings will give level flight at that airspeed

Example 1:
~ a Robinson R22 will take approximately 21 inches of manifold pressure to maintain level flight at 75 knots
~ this will be influenced by factors such as aircraft weight, density altitude, and the performance characteristics of the particular aircraft
~ under most circumstances the value will be very close, and only a minor adjustment to power will be required to compensate for these factors
~ by knowing what attitude will give 75 knot cruise, and what power setting is required,
~ a pilot can very quickly make the pitch attitude and power setting adjustments needed to result in the desired performance
~ this is especially useful when converting from one flight configuration to another,
~ such as from climb to cruise, or from cruise to descent

Example 2:
~ 15 inches of manifold pressure at 60 knots will give between 300-500 feet per minute (=5,5-10 km/h) descent rates
~ this is a comfortable configuration for descending in the traffic pattern until approach angle intercept occurs

Other helicopters have different power settings for the same flight configurations.
Most pilots will quickly learn a few of the most commonly used configurations.
Interpolation will give them intermediate configurations which they have not memorized,
and typically only 3 or 4 configurations need be memorized.
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