Falcon Heavy prepped for static fire test


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Capitalism in space: SpaceX has raised its first Falcon Heavy rocket onto the launchpad in preparation for the static fire test required before the rocket can do its first launch.

SpaceX’s first Falcon Heavy rocket has been raised vertical at pad 39A for the second time in advance of a planned hold-down test-firing of its main engines tomorrow during a window that extends from 1-7 pm EST (1800-0000 GMT). Kennedy Space Center employees were told to expect an estimated 15-second firing.

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7 comments

  • David Scott

    We were in Robinson Tx on January 4. Around 2-3 CDT and I’m pretty sure i heard a test fire off a space X engine. It lasted over a minute. At 20 miles the noise and vibration was very inpressive.

    We had driven thru McGregor on Hwy 84 about 30 mins earlier. Wish i had been delayed a bit.

  • mivenho

    Fifteen seconds! I wonder if the extra duration is to better analyze vibrational modes / stresses on the multi vehicle structure.

  • Jason Hillyer

    Is it true that if Falcon Heavy is going to explode, it will likely explode during the static fire test?

  • Jason Hillyer: No, the static fire test might work fine, but then during launch going through the atmosphere things might go south, especially when the rocket goes through Max Q, the period when the atmosphere is thickest and the rocket is under the greatest stress.

  • Edward

    Jason Hillyer,
    There is also low probability that something goes wrong during separation of the boosters, the launch up to that point will have some amount of tension and concern. After that, it should look like a regular launch. Except for two boosters landing back at Cape Canaveral Air Station and a third one landing on the drone ship Of Course I Still Love You. The video for all that action should be interesting. Or spectacular, if it does not go as planned.

    Using strap-on boosters is not new for rocketry, so SpaceX benefits from the experience of other rockets, but this is a new experience for SpaceX. Even if all goes well with this launch, they are likely to learn something.

  • Edward

    Robert,
    I knew that there were examples of rocket failure at Max Q, but I only just now looked for one. The unmanned test, Mercury Atlas 1 (MA-1) failed at Max Q:
    https://en.wikipedia.org/wiki/Mercury-Atlas_1
    “The Atlas rocket suffered a structural failure 58 seconds after launch. The vehicle at that time was at approximately an altitude of 30,000 feet (9.1 km) and 11,000 feet (3.4 km) down range when it was passing through Max Q and all telemetry signals suddenly ceased. Because the day was rainy and overcast with thick clouds, the booster had been out of sight from T+26 seconds and it was impossible to see what happened.”

    Your statement “Max Q, the period when the atmosphere is thickest” is a bit misleading. The density, or thickness, is less than at sea level, but the speed of the rocket is such that the atmospheric forces — dynamic forces — on the rocket are greatest. This is the reason for the obsession with Max Q.
    https://www.quora.com/Why-is-max-q-important-in-a-rocket-launch

    All,
    Rocket launch profiles are designed in order to keep the Max Q dynamic forces from overwhelming the structure of the rocket, and rocket structures are designed to survive the anticipated Max Q forces. This often means that liquid fuel engines (or hybrid engines) are throttled down to manage the speed, thus the forces, during this part of the launch. Launches (from the ground) start out straight upward in order to get into the thinner parts of the atmosphere quickly, but not so quickly that the dynamic forces become too large. There is also a need to turn downrange in order to begin developing the horizontal orbital speed, too. These are some of the factors that drive the trade offs in launch profile design.

    Falcon Heavy’s launch profile has the side boosters separate before the inner core first stage main engine cut off. Since the three rockets are (virtually) identical, this suggests that for some part of the launch the inner core does not produce as much thrust as the side boosters, because the core will likely burn more fuel, after booster separation, than the boost-back amount used by the side boosters.

  • Edward: You are right, my description of Max Q is not exactly accurate. I was writing quick, and looked for a short way to simplify the description. Always a mistake.

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