With both front and rear hatches new in 2018 for Perlan 2, we wanted to verify their strength. The pilots decided what the expected pressure differential at our highest altitude might be. Then we tested above that for a margin of safety. Our Life Support System Display LSSD monitors a plethora of data. This time we wanted to pressurize to 9.5 differential psi to test the new hatches.
First we demonstrated several normal pressurizations inside the hangar. Then the Perlan 2 glider was taken outside the hangar on a nice day with above freezing temps. We were extremely careful to position the hatches from the outside as no one would be inside the cockpits for this test. That meant tape to be able to pull the hatches into precise position. There were loops to be able to slide a stick through so a hatch wouldn't fall inside if pressure was inadvertantly lost.
Jim wrote the test plan and added edits as needed. Tim ran the air supply from inside the hangar. Morgan and Ed monitored the LSSD screen in CapComm. The pressurization was slowly advanced and allowed to leak out while measuring the leak rate. Then the pressure differential was slowly taken into the red zone. After the highest differential the leak rate was measured on the way back down to compare with earlier times. The new hatches passed with flying colors! After the test we studied the hatch seals for additional information about the fit. Very encouraging data! Perlan Soars! Jackie