Altitude and Altitude Rate Computation - Block Diagram
Figure 005
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Corrected Altitude Computation - Block Diagram
Figure 006
R 1EFF : 051-099, 106-149, 204-299, 301-399, 1 34-13-00Page 23 1401-499, 1Config-3 Aug 01/05 1 1 1CES 1 The corrected altitude is calculated by a shift of the pressure altitude to a value corresponding to the entered baro correction. The result is sent on label 204 for CAPT baro corrected altitude and label 220 for F/O baro corrected altitude.
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(c) CAS/Mach computation (Ref. Fig. 007) The ADR software computes these different parameters: label 206 Computed Airspeed label 205 Mach label 207 Maximum Allowable Airspeed. The CAS and Mach computation is based on the conversion of the impact pressure: impact pressure = Pt - Ps.
-the CAS computation converts input of impact pressure to output corresponding to computed airspeed with: ______________________ / Qc 2/7 CAS = Cso X V 5 X ((-- + 1) - 1)
Po
CAS = Computed Airspeed in knots
Cso = Speed of sound under standard day sea level
conditions = 661.4746 kts
Qc = Impact pressure in hPa
Po = Standard day sea level pressure = 1013.25 hPa
For accuracy reason, the CAS is output with a valid (NO) SSM only after 30 kts. If the CAS is below 30 kts, the label 206 indicates 0 kt with SSM = NCD.
-the Mach computation converts Qc/Ps to Mach, with:
_______________________
/ Qc 2/7
MACH = V 5 ((-- + 1) -1)
Ps MACH = Mach number Qc/Ps = Ratio of impact pressure to static pressure
If Mach is below 0.1, the label 205 indicates 0 with SSM = NCD.
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CAS/Mach Computation - Block Diagram
Figure 007
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(d)
SAT/TAS computation (Ref. Fig. 008) The ADR software calculates these different parameters: label 213 BNR Static Air Temperature (SAT) label 233 BCD Static Air Temperature (SAT) label 210 BNR True Airspeed (TAS) label 230 BCD True Airspeed (TAS).
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the calculation of the BNR SAT converts TAT to SAT with: TAT SAT = ---------- 273.15 2
1 + 0.2M SAT = Static Air Temperature (in deg. C) TAT = Total Air Temperature (in deg. Kelvin) M = Mach number (corrected for static source error)
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the calculation converts Static Air Temperature from BNR to BCD format.
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the calculation of the BNR TAS converts Mach and SAT to TAS with: ___
/ TAS = 38.96695 x M x V SAT TAS = True Airspeed (in knots) M = Mach Number (corrected for Static Source Error) SAT = Static Air Temperature (in deg. Kelvin)
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the calculation converts True Airspeed from BNR to BCD format. For accuracy reason, the TAS is output with a valid (NO) SSM only after 60 kts. If TAS is below 60 kts, the label 210 indicates 0 kt with SSM = NCD.
(e)
VMO/MM0 computation (Ref. Fig. 009) The software determines the normal or alternate VMO/MMO law selected by the VM0/MM0 input 2 discrete state; then it computes the label 207 Maximum Allowable Airspeed. This airspeed is based on the Maximum Allowable Airspeed under a certain altitude and on the Maximum Allowable Mach above this altitude. It is always indicated in knots and decreases when the altitude increases.
NOTE : At a constant Mach, the Vc value decreases when the
____
altitude increases.
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