Returning Falcon 9 first stages generate a triple sonic boom from the grid fins and engine exhaust
the verdict
SUPPORTED
the evidence backs this
refutedsupported
the weight of evidence
2 sources for · 0 against
Peer-reviewed literature establishes that returning Falcon 9 first-stage boosters generate a triple sonic boom during descent, driven by aerodynamic interactions from components such as the grid fins and lower booster structures.
When the SpaceX Falcon-9 rocket booster descends through the atmosphere after a launch, it produces a sonic boom with three shocks in the far field, rather than the usual two-shock N-wave. In this Letter, the additional shock's origin is explained using sonic boom theory, nonlinear propagation modeling, computational fluid dynamics, and photographic evidence. The extra central shock results from a forward-migrating compression wave caused by the grid fins merging with a rearward-migrating rarefaction wave caused by the lower portions of the booster, including the folded landing legs.
# Why did the returning F9 first stage generate a triple sonic boom?
Tags: spacex, falcon-9, landing, reuse
- Score: 10
- Views: 1439
- Answers: 2
- Answered: yes
- Asked by: geoffc (81207 rep)
- Asked: 2015-12-23
- Edited: 2015-12-24
- Site: space
## Question
If you watch the landing footage of the Orbcomm OG2 mission, where the first stage of the F9 1.1 Full Thrust lands, just after it touches down, shuts down the engine, a triple boom is heard.
Most videos of people watching it, seem to suggest they thought it exploded, but with no fire/explosion visible they get over that fear quickly.
Even Elon Musk initially thought the booms were an explosion.
If you look at the various vudeos, it really looks that way, due to distance and speed of sound hitting the timing just right.
In this video the boom arrives before the landing, so still up high, less to possibly reflect off.
But why a triple boom? Shuttle had a double boom, one from the leading edge of the wings, the second from the top of the tail.
## Answers
### Answer by geoffc (score: 5)
Current speculation seems to be one boom for the leading edge, one for the hyper-sonic grid fins, and the third for the trailing
Everything we examined (2)
This check searched the claim as stated. It did not run a separate search for evidence against it.