Drop tests of full-scale capsules from a C-130 airplane were started to check parachute deployment and spacecraft stability. Preliminary drops of the parachute system were made from a NASA helicopter at West Point, Virginia. These drops involved the use of a concrete-filled drum attached to an operating canister system. The purpose of this phase was to demonstrate the adequacy of the mechanical system of deploying the parachutes. Subsequently, the drops were made by the C-130's at Pope Field, North Carolina, from low levels to perfect a means of extracting the spacecraft from the aircraft. Full-scale spacecraft and operating parachutes were used in these drops, and all operational features of the drop-test program were worked out. The next phase was the research and development drops offshore of Wallops Island, Virginia, and the objectives here were as follows: to study the stability of the spacecraft during free fall and with parachute support; to study the shock input to the spacecraft by parachute deployment; and to study and develop retrieving operations.
Balloon flights were planned for high-altitude qualification tests of the complete spacecraft, including all instrumentation, retrorockets, drogue parachute system, and recovery. Later balloon flights would be manned to provide as much as 24 hours of training followed by recovery at sea. The Space Task Group made surveys of organizations experienced in the balloon field and recommended that the Air Force Cambridge Research Center be given responsibilities for designing, contracting, and conducting the balloon program.
In the recovery landing system, the extended-skirt main parachute was found to be unsafe for operation at altitudes of 10,000 feet and was replaced by a 'ring-sail' parachute of similar size. This decision was made after a drop when the main parachute failed to open and assumed a 'squidding' condition. Although little damage was sustained by the spacecraft on water impact, parachute experts decided that the ring-sail configuration should be adopted, and the air drop spacecraft were fitted.
A deliberate thrust misalignment of 1 inch was programed into the escape combination. Lift-off was effected cleanly, and a slow pitch started during the burning of the escape rocket motor. The tower separated as scheduled and the drogue and main parachutes deployed as planned. The test was fully successful.
Two small-scale spacecraft escape-tower combinations were launched successfully at Wallops Island. On the next day a full-scale spacecraft escape system was launched. The complete sequence of events - escape system firing, escape tower jettisoning, parachute deployment, landing, and helicopter recovery - was satisfactory.
The Space Task Group oficials determined that the spacecraft could be tested environmentally in the Lewis Research Center's altitude wind tunnel. This included correct temperature and altitude simulations to 80,000 feet. The pilot could exercise the attitude control system and retrorockets could be fired in the tunnel. Because an active contract did exist with the Air Force, it was decided the two balloon drop tests with unmanned boiler-plate spacecraft would be accomplished.
McDonnell selected Northrop as the subcontractor to design and fabricate the landing system for Project Mercury. Northrop technology for landing and recovery systems dated back to 1943 when that company developed the first parachute recovery system for pilotless aircraft. For Project Mercury, Northrop developed the 63-foot ring-sail main parachute.
Testing was completed to check the effectiveness of the drogue parachute as a stabilizing device. The drogue parachute was fully qualified for deployment at speeds up to Mach 1.5 and altitudes of up to 70,000 feet. Ordinarily, during the operational phase of Project Mercury the drogue parachute was deployed at 40,000 feet, so the component well met operational requirements.
Funds were approved by NASA Headquarters for the following major changes to the Mercury spacecraft: egress hatch installation (CCP-58-1), astronaut observation window installation (CCP-73); rate stabilization and control system (CCP-61-2), main instrument and panel redesign (CCP-76), installation of reefed ringsail landing parachute (CCP-41), and nonspecification configurations of spacecraft (CCP-8). With reference to the last item, the original contract with McDonnell had specified only one spacecraft configuration, but the various research and development flight tests required changes in the configuration.
The entire qualification testing program consisted of 56 airdrops of full-scale engineering models of the Mercury spacecraft from C-130 aircraft at various altitudes up to 30,000 feet and from helicopters at low altitudes to simulate off-the-pad abort conditions. This test program, under contract to Northrop, had spanned one and one half years.
Instruction was provided to the astronauts to develop techniques and procedures for using the personal parachute as an additional safety feature in the Mercury program. This parachute was only used during the Mercury-Redstone 3 (MR-3) mission manned by Alan Shepard.
Twenty spacecraft aerial drop tests were planned for the Mercury extended range or 1-day mission. One of the prime objectives was to determine if the 63-foot ringsail main recovery parachute met all Mercury mission weight requirements. Tests were scheduled to be conducted at El Centro, California, and all tests would be land drops. This test program was designated Project Reef.
Project Reef, an airdrop program to evaluate the Mercury 63-foot ringsail main parachute's capability to support the higher spacecraft weight for the extended range or 1-day mission was completed. Tests indicated that the parachute qualified to support the mission.