The causes behind the launch failure of Firefly’s Alpha rocket in April
In late August the FAA and Firefly completed the investigation into the launch failure of Firefly’s Alpha rocket in April, clearing the way for the company to resume launches.
At the time however this approval was reported here merely as a quick link on X. The company however also published its conclusions at that time which explained the cause of the failure. For completeness I post that now, describing what happened just after the first stage separated from the second stage.
Alpha’s first stage then experienced a rupture milliseconds after stage separation. The pressure wave hit Alpha’s second stage, leading to the loss of the engine’s nozzle extension and substantially reducing stage two thrust. The second stage was able to recover attitude control and continued to ascend to an altitude of 320 km until running out of propellant. The vehicle was three seconds short of achieving orbital velocity and five seconds short of the target payload deployment orbit.
The ground-based video, onboard telemetry, post-flight empirical testing and Computational Fluid Dynamics analysis corroborated excessive heat from Plume Induced Flow Separation as the most probable root cause of the mishap. Alpha Flight 6 flew a higher angle of attack than prior missions. Plume-induced flow separation intensified heat on the leeward side reducing structural margins, causing the booster to rupture from stage separation induced loads.
Fortunately, the corrective actions are straight forward: increase thermal protection system thickness on Stage 1 and reduce angle of attack during key phases of the flight. Corrective actions have already been implemented.
The company expects to resume flights in the very near future, probably before the end of 2025.
In late August the FAA and Firefly completed the investigation into the launch failure of Firefly’s Alpha rocket in April, clearing the way for the company to resume launches.
At the time however this approval was reported here merely as a quick link on X. The company however also published its conclusions at that time which explained the cause of the failure. For completeness I post that now, describing what happened just after the first stage separated from the second stage.
Alpha’s first stage then experienced a rupture milliseconds after stage separation. The pressure wave hit Alpha’s second stage, leading to the loss of the engine’s nozzle extension and substantially reducing stage two thrust. The second stage was able to recover attitude control and continued to ascend to an altitude of 320 km until running out of propellant. The vehicle was three seconds short of achieving orbital velocity and five seconds short of the target payload deployment orbit.
The ground-based video, onboard telemetry, post-flight empirical testing and Computational Fluid Dynamics analysis corroborated excessive heat from Plume Induced Flow Separation as the most probable root cause of the mishap. Alpha Flight 6 flew a higher angle of attack than prior missions. Plume-induced flow separation intensified heat on the leeward side reducing structural margins, causing the booster to rupture from stage separation induced loads.
Fortunately, the corrective actions are straight forward: increase thermal protection system thickness on Stage 1 and reduce angle of attack during key phases of the flight. Corrective actions have already been implemented.
The company expects to resume flights in the very near future, probably before the end of 2025.
