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Third Stage Design Problem Cause of Most Recent Proton Failure

Posted by timothy on from the no-richard-feynman dept.

schwit1 writes: The Russian investigation into the latest Proton rocket failure has concluded that the failure was caused by a design failure in the rocket's third stage. The steering third stage engine failed due to excessive vibration as a result of an imbalance in a rotor of a pump unit. While it is always possible for new design issues to be discovered, I wonder why this problem hadn't been noticed in the decades prior to 2010, when the Proton began to have repeated failures.

11 of 72 comments (clear)

  1. Redesigned at some point, obviously by gman003 · · Score: 4, Interesting

    The Proton rocket has gone through a number of redesigns over its long life. The latest version, the Proton-M, first flew in 2001, and they kept flying the Proton-K for many years (for reasons I actually don't know). They've only done 90 flights of the Proton-M, and half of them were in that post-2010 period of "repeated failures" (although they had about as many failures for pretty much all of the 2000s as well).

    I would highly expect the faulty pump to have been redesigned with the Proton-M modifications, based simply on that analysis.

    1. Re:Redesigned at some point, obviously by garyisabusyguy · · Score: 4, Interesting

      In the Proton M there is a new upper stage that uses a store-able fuel
      There was an effort to move away from 'foreign' parts suppliers, notably Ukrainian
      http://en.wikipedia.org/wiki/P...

      --
      Wherever You Go, There You Are
    2. Re: Redesigned at some point, obviously by Anonymous Coward · · Score: 5, Interesting

      The real reason behind the switch from Proton-K to Proton-M was that the M one had a digital guidance computer, that could've been programmed by a rookie engineer, while Proton K relied on analog circuits that had to be rebuilt for every trajectory/payload combination.

      --Russian vodka engineer

  2. Telemetry by Anonymous Coward · · Score: 2, Interesting

    Improved telemetry and sensors may have helped.

  3. It's always Stage III by Etherwalk · · Score: 3, Interesting

    The Proton rocket has gone through a number of redesigns over its long life. The latest version, the Proton-M, first flew in 2001, and they kept flying the Proton-K for many years (for reasons I actually don't know). They've only done 90 flights of the Proton-M, and half of them were in that post-2010 period of "repeated failures" (although they had about as many failures for pretty much all of the 2000s as well).

    I would highly expect the faulty pump to have been redesigned with the Proton-M modifications, based simply on that analysis.

    IIRC, Stage III failures are responsible for a very high percentage of launch failures.

    Although IIRC, Clancy once wrote about one being faked in order to put a spy satellite into orbit without people realizing it was a spy satellite. Of course, the tech wasn't as good then...

    1. Re:It's always Stage III by robbak · · Score: 4, Interesting

      That is really not that surprising. All the design constraints in rocketry really come to a head in the last stages. Every kilogram of mass in your last stage is a kilogram less payload you can carry, and it is where you really need the most efficiency, the peak isp, so you want to push the pressures and temperatures as high as you can.

      As light as you can make it, as powerful as you can make it. This leads to fine tolerances and making the design only as strong as it needs to be.

      --
      Prediction for end of Universe #42: Fencepost error in Quantum_bogosort.cpp
    2. Re:It's always Stage III by Anonymous Coward · · Score: 5, Interesting

      I think too, not sure, but with the third stage usually you're fully ballistic when it's running. (don't need to fight gravity)

      Absolutely right. Play Kerbal Space Program for a few hours, and you really feel this. All your upper-stage engine needs to do is give you enough horizontal velocity to stay in orbit. So you want it to be as efficient as possible, and as weak as possible (since a weak engine is lighter), while still allowing it to finish its burn before you fall back into the atmosphere.

      The first stage is quite different. As you said, the first 1g of acceleration it gives you is wasted fighting gravity, so you want the thrust-to-weight to be as high as possible to minimise this fractional loss. On the other hand, go too fast too soon, and you're losing energy to drag. You don't want to go really fast until you're above most of the atmosphere. The mathematical formulation of this is called "Goddard's problem", and the optimum solution is something like: accelerate flat-out until you reach the speed where atmospheric drag becomes significant, then cut your thrust back, and gradually ramp your acceleration back up to max again as the air thins out.

  4. Lack of technical expertise by smooth+wombat · · Score: 3, Interesting

    With Russia's invasion of Ukraine not going quite as planned, and Russia now building up another invasion force on its border with Ukraine, the trained specialists who would have caught this error have been rerouted to help produce more advanced rockets for the military.

    The problem is the sanctions imposed on Russia for its invasion are hurting its ability to pay its people. Some have gone as long as four months without pay and even when they are paid, it's not the full amount. Since there is no money to be made working on their space program, these people go to the military side which Putin continues to pour money into while grocery shelves start to go bare around the country.

    Expect to see more such accidents until Russian troops are out of Ukraine and there is cooperation with the West who can provide technical guidance in these matters.

    --
    We will bankrupt ourselves in the vain search for absolute security. -- Dwight D. Eisenhower
  5. Re:Design flaw? by trout007 · · Score: 4, Interesting

    Not necessarily. I am a Mechanical Engineer and I work in a machine shop. Every part you design has tolerances on every dimension. But if you work with machinists with lots of pride like I do they will tend to try to hit the tightest tolerance they can just to keep up good practice and produce nice parts. So I can have a design that when I send it to my shop works flawlessly. But if I send the same drawings to an outside shop and they take full advantage of the tolerances I allowed I might be in for a surprise.

    The same could be true here. The design worked because one shop produced parts that exceeded the specifications but might fail for a certain combination of tolerances that are still within the allowed design.

    --
    I love Jesus, except for his foreign policy.
  6. Re:Beautify the world! by JavaBear · · Score: 3, Interesting

    Maybe it is time to sterilize racist bigots, and Anonymous Cowards.

    Until then, maybe it's time /. added a block on Anonymous Cowards for the first 2-3 hours after a post is published, or has at least 100 messages.

  7. Re: Design flaw? by oobayly · · Score: 3, Interesting

    To be fair, the Soviets made some amazing equipment during the cold war. The Americans for example were amazed by the NK-33 rocket engine. One of Lockheed's engineers described how they couldn't have made a similar engine in the US because of design concepts. Russian design engineers gave the design to the manufacturing engineers who in turn would refine the design during manufacturing. The design was then built, tested and refined iteratively. American engineers were less likely to build a design that was likely to fail - the design had to be refined before it was built which meant that they were more likely to be conservative.

    UK's Channel 4 had a series called Equinox that did an episode on it.