More details about SpaceX’s fairing recovery plans


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Link here. The article has some additional excellent images, but it was this paragraph that I thought was most significant:

To oversimplify, after launch, the payload fairing separates (mechanically) from the second stage once Falcon 9 or Heavy has left behind the majority of Earth’s atmosphere. After separation, each fairing half orients itself for a gentler reentry into the atmosphere with cold nitrogen gas thrusters, likely the exact same thrusters used in part to achieve Falcon 9’s accurate and reliable landings. Due to their massive surface area and comparatively tiny weight, fairing halves effectively become exceptionally finicky and awkward sails falling through the atmosphere at insane velocities, with the goal generally being to orient each half like a boat’s hull to provide some stability. Once they are low enough, assuming they’ve survived the journey from TEN TIMES THE SPEED OF SOUND and 62 MILES above Earth’s surface to a more reasonable ~Mach 0.5 and maybe 5 miles of altitude, the fun parts begin. At this point, each fairing half deploys a GPS-connected parachute system (a parasail, to be exact) capable of directing the massive hunks of carbon fiber and aluminum to a very specific point on the surface of the ocean.

What we don’t yet know is whether SpaceX will have cameras on the fairing, and if so, whether they will make those images available to the public, during launch.

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16 comments

  • Kirk

    Recall this 2015 SpaceX video from a GoPro camera mounted in a fairing showing its view for two minutes following separation: https://www.youtube.com/watch?v=4_sLTe6-7SE

  • Kirk

    The Falcon 9 (second flight of core 1038, last flown during last August’s FORMOSAT-5 mission) is now erect at Vandenberg,
    and initial sightings suggest that the fairing being used for tomorrow’s 06:17 PST / 09:17 EST Paz launch appears to be the slightly larger diameter Fairing version 2 previously mentioned by Mr. Musk and expect to debut sometime soon. Nothing definitive yet; just eyeballing the fairing in some telephoto shots. https://forum.nasaspaceflight.com/index.php?topic=44892.msg1790655#msg1790655

  • Kirk

    A nice shot of the Paz launcher, taken from the SpaceX home page: https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=44892.0;attach=1478653;image

    From what I can make of the launch weather forecast (which gives a 90% Go / <10% concern for Ground Winds) it looks to be clear and might be a spectacular launch, with the booster breaking into the sunlight a bit before T+1:20. So if you live in southern California, make sure to get up and watch this one. The beauty of the Iridium 4 launch was visible as far east as Phoenix, but that won't work out as well this time as the sun will have already risen for those east of CA. One of these days I will make it out to CA to view a Vandenberg launch, and I could only hope for a forecast like this.

  • Perhaps someone can educate me.

    While understanding that an orbital launcher is a highly engineered and very expensive piece of equipment, I’d considered the fairings to be *the* most disposable parts, akin to wrapping on a package. Is the fractional cost of the fairing really high enough to justify the recovery and certification effort, or is this more of ‘doing it because we can’ sort of thing?

  • Edward

    Blair Ivey asked: “Is the fractional cost of the fairing really high enough to justify the recovery and certification effort, or is this more of ‘doing it because we can’ sort of thing?

    The fairing is said to be a $5 million item, and the article mentioned that they are 10% of the current price tag for a launch. If SpaceX can successfully recover them as reusable items, then they can bring down their price of a launch even further. They may have been the most disposable part because of their relatively low cost (compared with the disposable engines). However, when penny pinching then every penny counts, but the old-school method of charging all the traffic will bear for a launch, not so much.

    I am fairly sure that SpaceX is anticipating both heavy competition in the distant future and a nice profit with which to do additional research and development in the near future. SpaceX is earning a reputation for out of the box thinking, and this experiment is more of that thinking. If it does not work, it will not be the first time that they put money into an idea that did not work out.

    As for “wrapping on a package,” fairings have to be designed to take the forces of max Q, the heat generated by the friction with the atmosphere, the vibration caused by the rocket and the passing atmosphere (acoustic testing of satellites is to verify that the satellite can withstand the terrific noise generated by the vibrating fairings), yet separate from each other and the launch vehicle with great reliability and without damaging the payload. The “easy” part is venting them as the rocket climbs into the lower pressure regions of the atmosphere without the pressure building up due to slow depressurization or decrease too fast due to Bernoulli principle, so unlike the propellant tanks, they are not pressurized to help strengthen the structure. I forgot to mention that they have to be lightweight despite all the forces they must withstand.

    Even the fairings turn out to be rocket science.

  • @ Edward:

    Color me educated. Thank you.

  • Kirk

    “Standing down today due to strong upper level winds. Now targeting launch of PAZ for [Wednesday] February 22 at 6:17 a.m. PST from Vandenberg Air Force Base.” https://twitter.com/SpaceX/status/966313372814749701

  • wayne

    Edward-
    enlighten me as to how the fairing pieces detach. Do they use any explosive-bolt type apparatus?

  • Kirk

    SpaceX tends to shy away from explosive bolts due to the inability to test flight hardware and the inherent lack of reusability, and as far as I know do not use any. Do you know, Edward?

    Here is video of a SpaceX fairing separation test in a vacuum chamber.

    https://www.youtube.com/watch?v=LtI1V624vWM

    I suspect they use electro-mechanical latches and pneumatic pushers, but the video doesn’t shed much light on their choice of mechanism.

  • geoffc

    Blair Ivey: In addition to the cost, it turns out the manufacture of the fairings takes large equipment (autoclaves to cure C-F) which eat space, and are slow to make.

    If they want to launch 30 times this year, they basically need 30 fairings (Minus Dragon launches, which is what 4-5 this year?) so they need to make a lot of these things.

    If they can reuse and make fewer they can get by on existing equipmet instead of perhaps scaling horizontally.

    There are some good questions/answers on this topic at Space.stackexchange.com like:

    Falcon 9 fairings cost and reusability
    https://space.stackexchange.com/q/14745/51

    Do each of the fairing halves now use thrusters post-deployment? How does that work?
    https://space.stackexchange.com/q/20918/51

  • Calvin Dodge

    Per the “Falcon 9 User Guide”, all second stage retention, release, and separation mechanisms are pneumatic.

  • Edward

    wayne asked: “enlighten me as to how the fairing pieces detach. Do they use any explosive-bolt type apparatus?

    And Kirk asked: “SpaceX tends to shy away from explosive bolts due to the inability to test flight hardware and the inherent lack of reusability, and as far as I know do not use any. Do you know, Edward?

    I have not looked into their mechanism, but I do know that SpaceX has moved away from pyrotechnics for separating the fairings. As Calvin Dodge noted — and as I recall — they also use mechanical means for separating stages.

    One thing that has impressed me is just how fast the fairings fly away from the centerline as they separate. I am surprised that pneumatics have that kind of oomph to move them so fast at actuation (the article says that each is 1000 kg, about as much as a car); that must be quite some force applied — and the fairings would have to be designed to withstand that force, too, and remain closed even though such large, lightweight structures are held at only a few points.

    A problem with pyrotechnics (explosive bolts, guillotine/cutter, valves, etc.) is that they impart shock into the rocket and spacecraft. Shocks are not good for some mechanisms, such as momentum wheels/reaction wheels; the bearings do not take well to such treatment. (A couple of decades ago, my brother worked at a company that made data storage, and they found that the shock of the units rolling down the industrial roller tracks caused the disc drives to have shorter lives, so they quickly changed to other means of transport on the factory floor.) Shocks can damage other parts, too, and I have been involved in shock testing of satellite instrumentation and various equipment deployments.
    https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=2108&context=smallsat

  • Kirk

    From the source, Calvin. Thanks.

    Here are some photos of Mr. Steven returning to port with the fairing half they missed but then recovered from the water. (They also picked up parts of the other fairing half, but I don’t see it in these photos.) The high pressure pneumatic piping running around the inside of the fairing half is clearly visible in some of the photos.

    https://www.teslarati.com/spacex-recovered-fairing-spotted-mr-steven-boat/

  • Jhon

    Never mind about the Hispsat Launch, I was able to find an article and it seems to be a fairing issue.

  • Jhon: I suspect that SpaceX wants to revise the fairing for the Hispsat launch, based on what they learned from the Paz launch.

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