LJ-5A

From RixWiki

Project Mercury Missions

Flight Order

LJ-1		12 Aug 1959
BJ-1		9 Sep 1959
LJ-6		4 Oct 1959
LJ-1A		4 Nov 1959
LJ-2		4 Dec 1959
LJ-1B		21 Jan 1960
Beach Abort		9 May 1960
MA-1		29 Jul 1960
LJ-5		8 Nov 1960
MR-1		21 Nov 1960
MR-1A		19 Dec 1960
MR-2		31 Jan 1961
MA-2		21 Feb 1961
LJ-5A		18 Mar 1961
MR-BD		24 Mar 1961
MA-3		25 Apr 1961
LJ-5B		28 Apr 1961
MR-3		5 May 1961
MR-4		21 Jul 1961
MA-4		12 Sep 1961
MA-5		29 Nov 1961
MA-6		20 Feb 1962
MA-7		24 May 1962
MA-8		3 Oct 1962
MA-9		15-16 May 1962

Description of Mission

From SP-45 Mercury project summary

The Little Joe 5A mission was accomplished on March 18, 1961 from the Wallops Station launch site. This was an added mission, as a result of the failure of the Little Joe 5. For the Little Joe 5A mission production spacecraft 14 and the sixth Little Joe launch vehicle to be flown were used. The spacecraft was a basic Mercury configuration with only those systems installed that were required for the mission. As during the Little Joe 5 mission early ignition of the escape-rocket motor occurred. The mission was unsuccessful. However, unlike the Little Joe 5 mission, a backup spacecraft separation system was initiated by ground command and successfully separated the spacecraft from the launch vehicle and released the tower. Because of the severe flight conditions existing at the time of parachute arming, both main and reserve parachutes were deployed simultaneously. They filled and enabled the spacecraft to make a safe landing. All other active systems operated properly except that the cabin pressure-relief valve failed to maintain the spacecraft cabin pressure because of a piece of safety wire found lodged in the seat. The spacecraft was recovered and returned to the launch area in good condition. Analysis of data from the spacecraft proved that the early ignition of the escape rocket motor was caused by structural deformation in the spacecraft-adapter interface area. This early ignition permitted separation sensing switches to falsely sense movement and give the signal for the remainder of the sequence. The corrections applied were to reduce air loading in the area by better fairing of the clamp-ring cover, by increasing the stiffness of the switch mounting and reference structures, and rerouting the electrical signals from these switches through a permissive network.