The RA-1 is the military equivalent of the commercial Raider/Intruder system that is manufactured by Airborne Systems. The parachute system was designed for static line, ripcord and bottom of container (BOC) deployment configurations.
“When the Army did developmental test on the RA-1 at Yuma Proving Ground [Ariz.] a few years back, they did not test BOC deployments,” said Jacob St. Germain, 418th Flight Test Squadron, Airdrop engineer. “The Air Force, in particular Guardian Angel, desired the BOC configuration to maintain the capability they had with previous parachute systems like the MC-4. Our goal was to perform an initial assessment of the BOC deployment configuration of the RA-1 system and qualify it to proceed to operational testing.”
Guardian Angel is comprised of Combat Rescue Officers, pararescuemen, Survival, Evasion, Resistance, and Escape specialists dedicated to the Air Force core function of personnel recovery.
The BOC modification to the RA-1 was a pocket added to the bottom of the parachute pack to stow the pilot parachute, which is deployed into the free airstream to deploy the main parachute. To initiate deployment, parachutists remove the pilot parachute by hand and deploy it off to their side, it then pulls the main chute free.
Both BOC and ripcord are freefall deployment methods. In both cases, once the pilot parachute is inflated behind the parachutist, it should pull the main canopy deployment bag from its container. The suspension lines should feed out of stows on the deployment bag until fully elongated, at which point the deployment bag should open and release the main canopy.
“Since the pilot parachute is deployed directly into the freestream air, it should inflate more quickly and reliably than a ripcord. Most parachutists tend to prefer this method for that reason,” St. Germain said.
“With the ripcord deployment method, pulling the ripcord initiates the deployment of a spring-loaded pilot parachute into the air behind the parachutist. The risk with this method is that the pilot parachute is released into the stagnant pocket of air known as the ‘burble,’ which develops behind the parachutist. If the pilot parachute spring doesn’t provide enough force to clear the burble, you could end up with pilot parachute hesitation malfunction. At best case this results in a significant increase in altitude loss; at worst case it could mean a cutaway.”
St. Germain added that operational testing of the RA-1 in the BOC deployment configuration was scheduled to begin June 26 so the 418th FLTS had to test quickly and a C-12 Huron could not be scheduled that fast. Twenty-two test jumps were accomplished in total from a Skydive Perris Twin Otter aircraft.
“Skydive Perris has supplied aircraft for previous test programs and is very supportive of military clients. Without their support and flexibility, we could not have executed as efficiently and cost-effectively as we did.”
The first day consisted of 12 test jumps with exit altitudes at 10,500 feet to allow the parachutist free-fall time to perform practice touches of the BOC pilot chute before deploying it at 4,500 feet. The second day consisted of 10 test jumps where the parachutist immediately deployed his pilot chute after exiting the aircraft at 5,500 ft.
Data was collected through parachutist questionnaires, ground video and air-to-air video. Air-to-air video was accomplished using another parachutist from the 88th Test and Evaluation Squadron with a head-mounted camera. GPS, acceleration, pressure and temperature were captured with parachutist-mounted instrumentation.
“The ultimate goal for our test was to perform an initial assessment of BOC deployments with the RA-1 system. As long as the system was performing as expected and BOC deployment did not appear to cause any additional potential for malfunctions, we would qualify the system to move to operational test,” said St. Germain.
The RA-1 system with the BOC deployment method will go to operational testing by the 88th TES at Nellis Air Force Base, Nev.
“We are planning another test of the RA-1 system in the fall with the intent of reducing the current minimum deployment altitude.”