Nesis
— User’s Manual
7. Instruments
7
Instruments
7.1
Airspeed Indicator
The airspeed indicator is used to display indicated and true airspeed. Indicated airspeed
(IAS) is obtained form differential pressure sensor. The measured differential pressure (the
difference between the total pressure and the static pressure) is converted into velocity as-
suming ISA
24
conditions. When outside temperature is known, Nesis calculates true airspeed
(TAS) as well. Although only two values are shown on the indicator, the scale has several
markings as you can see on figure 49.
Figure 49:
Airspeed indicator optimized for an airplane using two step landing flaps.
The markings on the figure has the following meanings:
IAS (indicated airspeed)
is presented by a needle, which starts at center and ends
at scale markings.
TAS (true airspeed)
is shown as a number inside the window.
The
white range
is the normal range of operating speeds for the aircraft with the flaps
extended as for landing or takeoff. Depending on the aircraft, the white range may have
additional upper speed limits, which are based on flap extension step. See also
V
FE1
and
V
FE2
.
White range in a helicopter or gyrocopter indicates the best speed for the autorotation.
The
green range
is the normal range of operating speeds for the aircraft without flaps
extended. The lower limit of the green range is also referred to as
V
S
– stall speed or
minimum steady flight speed for which the aircraft is still controllable. The upper limit
is also referred to as
V
NO
– maximum structural cruising speed.
The
yellow range
is the range in which the aircraft may be operated in smooth air,
and then only with caution to avoid abrupt control movement.
The
redline mark
indicates the
V
NE
(velocity never exceeded), the maximum demon-
strated safe airspeed that the aircraft must not exceed under any circumstances.
24
ISA – International Standard Atmosphere.
Version 2.0
53
©
Kanardia
2011
