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posted by martyb on Sunday June 25 2017, @06:25PM   Printer-friendly

[Update #2 @ 2300 UTC: Corrected name of landing barge; Successful deployment of 10 @IridiumComm NEXT satellites to low-Earth orbit confirmed. .]

[Update #1 @ 2045 UTC: Launch was successful, first stage safely landed on the barge Of Course I Still Love You Just Read the Instructions, and the second stage is in a coasting orbit before commencing satellite deployment.]

Just three months ago — March 30, 2017 — SpaceX celebrated achieving the World's First Reflight of an Orbital Class Rocket. Just this past Friday, SpaceX repeated with a successful launch and recovery of its previously-flown, Falcon-9 first stage booster rocket with its BulgariaSat 1 mission. If you missed the launch, it is available on YouTube.

SpaceX is, however, not one to rest on its laurels and has scheduled a launch for today with an instantaneous launch window exactly two hours from now at 2025 UTC... and it will sport an upgraded set of grid fins which help steer the rocket during its re-entry.

According to Ars Technica:

During prior missions these grid fins, manufactured from aluminum with added thermal protection, have caught fire due to atmospheric heating. To address this problem the company has forged new grid fins from titanium. "Flying with larger & significantly upgraded hypersonic grid fins," Musk tweeted. "Single piece cast & cut titanium. Can take reentry heat with no shielding." The new fins are a bit heavier, but are designed for multiple re-uses as SpaceX seeks to more toward rapid reuse of its first stage booster.

Ars has a photo of grid fins (not extended) on a used Falcon 9 rocket which show the effects of atmospheric heating. Compare that picture to those on an unlaunched rocket.

Today's launch details:

June 25 - Falcon 9 • Iridium Next 11-20
Launch time: 2025 GMT (4:25 p.m. EDT; 1:25 p.m. PDT)
Launch site: SLC-4E, Vandenberg Air Force Base, California
A SpaceX Falcon 9 rocket will launch 10 satellites for the Iridium next mobile communications fleet. Delayed from October, December and April. Moved forward from June 29.

Today's launch can be viewed on SpaceX's webcast.


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  • (Score: 2) by mhajicek on Sunday June 25 2017, @07:02PM (2 children)

    by mhajicek (51) on Sunday June 25 2017, @07:02PM (#530928)

    It's sure prettier than aluminum when it burns.

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    The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
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  • (Score: 2) by mhajicek on Sunday June 25 2017, @07:15PM (1 child)

    by mhajicek (51) on Sunday June 25 2017, @07:15PM (#530931)

    Did a little Googling:

    "The ignition temperatures of aluminum wires obtained from their experiments were below the melting temperature of aluminum oxide (2327 K), ranging from 1913 to 2273 K, depending on the wire diameter and oxygen velocity."

    "PRODUCT NAME OR NUMBER: Titanium and Titanium Alloy ... AUTO-IGNITION TEMPERATURE (F): 2200F for metal in air, 480F for powder ..."

    1913K = 2983.73F

    So the Ti has a significantly lower ignition point. I also know it has significantly lower thermal conductivity, so heat from friction will remain localized and achieve higher temperatures. Unless there's something I'm missing I predict a light show.

    --
    The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
    • (Score: 2) by mhajicek on Sunday June 25 2017, @07:38PM

      by mhajicek (51) on Sunday June 25 2017, @07:38PM (#530938)

      Okay, this is probably what I was missing:

      "Burn-resistant β-alloys
      Titanium fires can occasionally occur in aero engines or in titanium-based heat exchangers used in the chemical industries. The addition of chromium in concentrations exceeding 10 wt% helps to improve the burn-resistance of titanium alloys.
      The alloy Ti-35V-15Cr wt%, has sufficient chromium to resist burning in an aero engine environment to temperatures up to about 510°C. The chromium is not found to be effective in binary Ti-Cr alloys where it does not encourage the formation of a continuous film of protective oxide."

      - http://www.totalmateria.com/page.aspx?ID=CheckArticle&site=ktn&NM=218 [totalmateria.com]

      --
      The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek