agc and manual control of the saturn v booster

AGC and Manual Control of the Saturn V Booster

Infoage Science/History Learning Center


Frank O’Brien




Necessary Background

• Overview of Saturn V Instrument Unit

• Apollo Guidance Computer / DAP

• Flight controls in the Apollo CM

• Abort Boundaries

• Saturn V takeover options

• Crew Simulator Experience



Instrument Unit

IU being lowered on top of S-IVB

All components located along inside wall of IU



Saturn Instrument Unit

• All booster guidance and control

• Platform: 3-axis stabilized, ST-124M

• Launch Vehicle Digital Computer– Single thread programming– “Time Bases” define mission phases– Triply Redundant– 32Kx28 bits, serial bus, 82us add time



Apollo CM Flight Controls

• Apollo Guidance Computer– DSKY– P11: Boost Monitor– Digital Autopilot

• Flight Director Attitude Indicator

• Main Console Switches

• Rotational Hand Controller



Apollo Guidance Computer

• Fully multiprogramming, interrupt driven

• Primary G&C interface

• Intuitive user interface– Verb-Noun communication language

• Verbs: Action to be taken• Nouns: Data to be acted on by Verb

• Boost Monitor: Program 11



Display and Keyboard (DSKY)



AGC Digital Autopilot

• Fully implemented in software

• DAP runs continuously in background

• Input parameters– Spacecraft configuration, weight– Attitude deadband– RCS Jet preferences

• Takeover configuration preloaded



AGC Program 11

• Independently monitors boost phase

• Calculates attitude errors– Displayed on FDAI error needles

• Displays velocity, altitude and H-dot

• Optionally displays orbital parameters

• (!) Is able to assume Saturn V takeover



Flight Director Attitude Indicator

• Primary spacecraft attitude indicator

• Modeled after traditional “8-ball”

• 4” ball with attitude markings

• Attitude error needles across face– Not unlike pilot’s ILS needles

• Rotational rate pointer along sides



Flight Director Attitude Indicator



Apollo CM Console Switches



Boost Monitor Cue Card



Saturn V Takeover

• LV Guidance light– LVDC detects an unrecoverable error

• LV Rate light– Excessive launch vehicle rates

• Pitch, Yaw > 5 deg/sec, Roll > 20 deg/sec

• Note: Abort region varies– T-0 -> T+120 sec - Pitch, yaw: 4 deg/sec– Remainder of boost - Pitch, yaw: 9 deg/sec



Takeover Options (1)

• LVDC failure during Open Loop guidance– Abort! (Automatic)– No Time-Tilt routine in AGC– No means to stage S-1C/S-II– Simulator experience

• Bending, sloshing, shear difficult to control

– Insufficient control authority for gimbal hardover



Takeover Options (2)

• Much easier in Closed Loop guidance• LV Guidance light

– Switch to CMC from IU control– Manual S-II / S-IVB staging required

• LV Rate light– Usually with LV Guid light– Possibly gimbal hardover or LVDC failure– DSKY Verb 46 to enable manual control



Manual Control Complications

• Saturn V is hardly a rigid body• Bending Moment

– Flexible structure, especially S-1C– Manual control authority during Time Base

1 and 2 may exceed max bending moment

• Propellant Sloshing– Significant for S-1C LOX & RP-1, S-II LOX

• Aerodynamics / wind shear



Simulation of Manual Control

• High-fidelity simulator built at Ames

• Performance criteria (earth orbit)– Delta H 1 Nautical Mile– Delta H-dot45 feet/sec– Delta V 10 Feet/sec

• Simulated performance well within criteria!



Backup (NASA NTRS)

• AC Delco Apollo 15 G&C manual• AS-503 Flight Manual• Astronics Systems of Saturn LV’s• Astronics Systems Handbook/Saturn LV• Description of Saturn G&C• Saturn 1B / V Astronics systems• Saturn V Manual Guidance• Saturn V LVDC Description• Apollo CSM Operations Handbook, Vol. 1

agc and manual control of the saturn v booster

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