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These three areas are very closely interrelated. Operating at airspeeds where you get
the best performance could be a limitation, since increasing or decreasing speed would
decrease desired aircraft performance. An example is L/D max, which is where the lift
to drag ratio is the greatest, or the airspeed where you get the most lift for the
least drag. Why is this important? This is the speed which would give the aircraft
the greatest gliding distance in the event of a complete power failure. You would need
this performance to reach a safe landing area. Changing speed would only reduce your
chances of making the field.
Weight and performance are closely interrelated. Increasing weight reduces performance.
This will cause an increased takeoff distance, reduce an aircraft's rate-of-climb
capability, and cause the true airspeed to be less at a given power setting and density
altitude. Although pilots should always compute the weight and balance performance data
for every flight, this information is especially important when transitioning to a new
aircraft.
Aircraft speeds, the various "V speeds," are also important for the safe
operation of any aircraft. It is recommended that pilots know the following V speeds that
apply to their particular aircraft:
- Vs0 - stalling speed, or the minimum steady flight speed in the landing configuration.
- Vs1 - stalling speed, or the minimum steady flight speed in a specified configuration.
- Vmc - minimum control speed with the critical engine inoperative (multi-engine aircraft)
- 1.3 Vs0 - recommended final approach speed in the landing configuration (if none
specified in the aircraft's documentation.
- Vx - speed for the best angle of climb.
- Vxse - speed for the best angle of climb (one engine inoperative in multi-engine aircraft).
- Vy - speed for the best rate of climb.
- Vyse - speed for the best rate of climb (one engine inoperative in multi-engine aircraft).
- Vlo - maximum landing gear operating speed.
- Vle - maximum landing gear extended speed.
- Vfe - maximum flap extended speed.
- Va - design maneuvering speed.
- Vne - never exceed speed.
- L/Dmax - airspeed that gives you the maximum gliding distance over the ground with
complete power failure.
Obviously these are a lot of numbers to memorize. However, remember that a pilot must
know how to operate his or her aircraft safely. Knowing V speeds is part of knowing
what to do not only when something goes wrong, but also when things are going right.
One way to remember these speeds is to write them on 3 x 5 inch cards and have them
where they can easily be reached for reference just prior to specific flight operations.
Many of these speeds are also marked on the instrument panel, some operating controls, and
the airspeed indicator.
There are many other limitations that a pilot needs to know, such as manifold pressure,
RPM, engine oil temperature and pressure, cylinder head temperature, hydraulic pressure
limits, volt and loadmeter readings, etc. Fortunately for most of us, the aircraft we
fly normally have these marked with color-coded indicators. However, it is important
to know where the indicators normally point, so that it will be easy to spot any change or
abnormal condition.
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