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Forty-nine years ago today, NASA successfully tested the Apollo Launch Escape System (LES) during a simulated abort of a boilerplate Apollo Command Module (CM).  The mission was the second of six test shots aimed at demonstrating that the LES could safely abort the CM under critical ascent flight conditions.

The Apollo Launch Escape System (LES) was designed to provide a positive means of crew esacpe in the event of booster failure during the early stages of ascent.  The LES incorporated a trio of solid rocket motors: the launch-escape motor, the tower-jettison motor, and the pitch-control motor.  The primary and largest rocket motor of the three was the launch-escape motor which generated 155,000 lbs of thrust.

NASA’s Little Joe flight test program involved the abort testing of boilerplate Apollo Command Modules using Little Joe II launch vehicles.  The purpose of the subject test series was to examine the performance of the Apollo CM and LES under highly stressing flight conditions.  The Little Joe flights were flown out of White Sands Missile Range (WSMR) between November 1963 and January 1966.

The Apollo Little Joe flight test series consisted of a pair of Pad Abort (PA) tests and a quartet of ascent abort (AA) tests.  Each PA mission involved flying a LES-CM combination to simulate an on-the-pad abort.  Such would be the case, for instance, should a Saturn launch vehicle explode on the launch pad.  The AA missions utilized Little Joe II launch vehicles to test the LES-CM at critical abort mode flight conditions.

Designated Abort Missions A-001 through A-004, the AA flight tests examined performance of the LES and CM under the following abort flight conditions: Transonic Abort (A-001), Maximum Dynamic Pressure Abort (A-002), Low-Altitude Abort (A-003) and Power-on Tumbling Boundary Abort (A-004).

The first of the AA missions (A-001) was launched from White Sands Missile Range, New Mexico at 12:59:59 UTC on Wednesday, 13 May 1964.  At an altitude of 15,400 feet during the ascent, the Little Joe II was intentionally self-destructed.  The LES fired as designed and propelled the Apollo CM boilerplate to 29,772 feet.  At this point, the 3-phase (drogue, pilot and main) parachute recovery system deployed and soft-landed the CM at a sink rate of 26 feet/second.  Total flight time from ignition to touchdown was 350 seconds.

Mission A-001 was entirely successful.  The LES worked as advertised and the boilerplate Apollo CM test article survived the transonic abort test in good shape.  The only anomaly noted was the collapse of one of the three main parachutes due to a broken riser.  Since the Apollo CM was designed to land safely on only two main parachutes, the collapsed parachute anomaly was not considered an issue.

History records that the A-002, A-003 and A-004 abort missions were subsequently and successfully flown in December 1964, May 1965 and January 1966, respectively.  Along with A-001, these missions helped qualify the Apollo LES and the CM earth landing system for manned missions.  Post-flight analyses revealed that had these abort tests had been manned, the flight crew would have landed safely in all cases.

Posted in Aerospace, History

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