This preview shows page 1. Sign up to view the full content.
Unformatted text preview: mmand Booster Nozzles Main engine Nozzle Diagnostic and flight information D SRI
Measures attitude of launcher and its movements in space C Horizontal velocity Backup SRI
Measures attitude of launcher and its movements in space; Takes over if SRI unable to send guidance info Strapdown inertial platform
C Horizontal velocity Ariane 5: A rapid change in attitude and high aerodynamic loads stemming from a
high angle of attack create aerodynamic forces that cause the launcher to disintegrate at 39 seconds after command for main engine ignition (H0). Nozzles: Full nozzle deflections of solid boosters and main engine lead to angle
of attack of more than 20 degrees. Self−Destruct System: Triggered (as designed) by boosters separating from main
stage at altitude of 4 km and 1 km from launch pad. OBC (On−Board Computer)
OBC Safety Constraint Violated: Commands from the OBC to the nozzles must not result in the launcher operating outside its safe envelope. Unsafe Behavior: Control command sent to booster nozzles and later to main engine nozzle to make a large correction for an attitude deviation that had not occurred. Process Model: Model of the current launch attitude is incorrect, i.e., it contains an attitude deviation that had not occurred. Results in incorrect commands being sent to nozzles. Feedback: Diagnostic information received from SRI Interface Model: Incomplete or incorrect (not enough information in accident report to determine which) − does not include the diag...
View Full Document
- Spring '09