Blaze FLIGHT-3 Operating Manual
Page 8
3.3 Auxiliary display 3
This page displays auxiliary related information. Barometer, TAS, Density altitude and OAT is shown.
BAR: (Barometer)
Ambient pressure can be displayed in either millibar or Inches of Mercury (Inch/Hg).
TAS: (True Airspeed)
What is TAS and how is it calculated ?
TAS is indicated airspeed (ASI) compensated for altitude and temperature. Often pilots ignore the effect of temperature
and only take altitude into account when converting ASI to TAS. For practical purposes this is quite accurate and gives a
good reflection on your true airspeed. Keeping in mind that ASI measurement is subject to errors caused by airflow
around your aircraft, there seems little point in taking this calculation to absolute resolution.
Again, we have decided to use a formula often used by pilots. This way the instrument reading will agree with what pilots
are used to.
Add 1.75% of IAS per 1000 ft (304.9 m) increase in altitude above sea level.
We assume here that IAS = RAS (rectified air speed).
DA: (Density Altitude)
Density altitude is a perceived altitude that pertains to your current altitude and temperature (and to a lessor extent on
your current moisture content of the air). Density altitude is relevant for performance calculations of your aircraft. Density
altitude affects the performance of your engine, propeller and airfoils. The most noticeable affects of density altitude are
length of take-off and landing runs and the ability of your aircraft to carry weight. There are several methods to calculate
density altitude, all result in readings that are very close to each other. We decided to implement a popular formula that is
often used by pilots to calculate density altitude at their location.
DA = SA + 118.6 * (T-T_s)
Where:
DA = Density Altitude in feet MSL
SA = Station Altitude in feet MSL for where the DA is being calculated
T = Actual air temperature (° K) at SA
T_s = Standard temperature (° K) at SA
OAT: (Outside Air temperature)
Outside air temperature can be measured using the external temperature probe. OAT can be shown in degrees Celsius
or degrees Fahrenheit.
