Taurus ELECTRO manual 472 ENG.pdf - Pipistrel

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TAURUS ELECTRO 15
Limitations
REV. 0
Indicated airspeed (IAS) to true airspeed (TAS) relation
Airspeed indicator measures the difference between total and static pressure (also called dynamic
pressure), which does not only change as speed increases, but is also linked with altitude. Flying at
high altitudes, where the air is getting thinner, results in misinterpreting airspeed which is being
indicated. The indicated airspeed value is actually lower than the true airspeed to which the aircraft
is exposed. The higher you fly, the bigger the difference between IAS and TAS. Be aware of this effect
especially when flying at high altitude at high speeds, not to exceed VNE unawarely. Bear in mind
this can happen even with the indicator still pointing within the yellow arc!
VNE at altitude (standard ICAO atmosphere)
The tables below indicate IAS to TAS relation for an altitude span of 0 - 5000m (0 - FL165) in different
atmospheres (variable is temperature). TAS is a constant of 225 km/h (122 kts) - VNE for the entire tables.
ISA-20 (-5°C at sea level):
Altitude (meters) 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Altitude (flight level) 0 FL16 FL33 FL50 FL66 FL82 FL98 FL115 FL131 FL148 FL165
VNE IAS (km/h) 225 225 223 218 213 209 203 198 194 189 185
VNE IAS (kts) 121 121 120 118 115 113 110 107 105 102 100
ISA-10 (5°C at sea level):
Altitude (meters) 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Altitude (flight level) 0 FL16 FL33 FL50 FL66 FL82 FL98 FL115 FL131 FL148 FL165
VNE IAS (km/h) 225 224 219 214 209 205 199 195 191 186 182
VNE IAS (kts) 121 121 118 116 113 111 108 105 103 100 98
ISA (15°C at sea level):
Altitude (meters) 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Altitude (flight level) 0 FL16 FL33 FL50 FL66 FL82 FL98 FL115 FL131 FL148 FL165
VNE IAS (km/h) 225 220 215 210 205 201 196 191 187 182 178
VNE IAS (kts) 121 119 116 113 111 109 106 103 101 98 96
ISA+10 (25°C at sea level):
Altitude (meters) 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Altitude (flight level) 0 FL16 FL33 FL50 FL66 FL82 FL98 FL115 FL131 FL148 FL165
VNE IAS (km/h) 220 215 211 206 202 197 192 188 184 179 175
VNE IAS (kts) 119 116 114 111 109 106 104 102 99 97 94
ISA+20 (35°C at sea level) :
Altitude (meters) 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Altitude (flight level) 0 FL16 FL33 FL50 FL66 FL82 FL98 FL115 FL131 FL148 FL165
VNE IAS (km/h) 216 211 207 202 197 193 189 184 180 175 171
VNE IAS (kts) 117 114 112 109 106 104 102 99 97 94 92
Note how VNE decreases at higher altitudes!
WARNING! Respect the Listed values at all times, not to exceed flutter critical
speed.