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> The program decides to officially stop trying to chase the off-center arrrestments and wire only arrestments. What does this mean? That the F-35C can only ho

> The program decides to officially stop trying to chase the off-center arrrestments and wire only arrestments. What does this mean? That the F-35C can only hook correctly when it lands very close to center? And what does "wire only" mean? Aren't all arrested landings on carriers "wire only"?

moelf 3y ago
I thought there's also the net they can use if, say, an aircraft lost tailhook
- jessriedel 3y ago
  Sure but that's emergency only.
euler_angles 3y ago
The whole purpose of this series of tests was to try to exercise the arresting gear in the most punishing ways. One way that's usually done is to try to arrest far off the centerline (where the arresting force will be applied far more intensely to one side) and also to try to have the arresting hook grab the wire while the jet is still wheels above deck (this slams the aircraft down, HARD) After this incident it was determined that we had fulfilled the intent of the test plan. Also, instrumented aircraft capable of doing arrestments were in short supply: the program only had two of them, and we pushed one to its very limit.
- jessriedel 3y ago
  > After this incident it was determined that we had fulfilled the intent of the test plan. Ok, so it was considered good enough? (This quote made it seem like the testing had failed and they were giving up: "The program decides to officially stop trying to chase the off-center arrrestments and wire only arrestments.) Also, I still don't understand what wire-only arrestments are. Aren't all arrestments wire only? Thanks.
  - hbrav 3y ago
    I think "wire only" means the hook catches while the wheels are still off the deck. I suppose that hard landing might have, in some ways, replicated the hard slam-down this would produce. Author, is that the case? Was the hard landing judged to have been a decent proxy for the wire-only arrestment?
    - bronson 3y ago
      Seems unlikely. One is slamming due to a heavy glideslope. Two is slamming due to a serious yank on the rear section. The airframe stresses and flight dynamics will be different.
      - euler_angles 3y ago
        Yeah, dynamics will be different, though caveat I am not a structures/loads engineer. I just don’t think anyone had the risk appetite to chance a test asset against a very difficult to achieve test point.
        hef19898 3y ago
        It is also fair to assume the decision to not do additional testing of wire-only arrests was well analyzed by the respective engineering teams. Program management does not take decisions like this by themselves.
        euler_angles 3y ago
        Absolutely. We had a whole carrier suitability team full of people who lived and breathed this stuff. It was just my responsibility to make sure the aircraft instrumentation system got them the data they needed, at a high enough quality, to empower their analyses and decision making process.
  - werrett 3y ago
    Based solely on the above description -- wire-only is when you don't have wheels on deck, also slowing the craft down.
- jessriedel 3y ago
  (BTW, the twitter link on your blog is mistakenly going to twitter.com. I think you meant to link to your account: https://twitter.com/the_engi_nerd https://twitter.com/the_engi_nerd Cheers!)
  - euler_angles 3y ago
    Oh, thanks for the spot. Not sure why it's doing that...
    - euler_angles 3y ago
      Fixed

moelf 3y ago

I thought there's also the net they can use if, say, an aircraft lost tailhook

jessriedel 3y ago
Sure but that's emergency only.

euler_angles 3y ago

The whole purpose of this series of tests was to try to exercise the arresting gear in the most punishing ways. One way that's usually done is to try to arrest far off the centerline (where the arresting force will be applied far more intensely to one side) and also to try to have the arresting hook grab the wire while the jet is still wheels above deck (this slams the aircraft down, HARD) After this incident it was determined that we had fulfilled the intent of the test plan. Also, instrumented aircraft capable of doing arrestments were in short supply: the program only had two of them, and we pushed one to its very limit.

jessriedel 3y ago
> After this incident it was determined that we had fulfilled the intent of the test plan. Ok, so it was considered good enough? (This quote made it seem like the testing had failed and they were giving up: "The program decides to officially stop trying to chase the off-center arrrestments and wire only arrestments.) Also, I still don't understand what wire-only arrestments are. Aren't all arrestments wire only? Thanks.
- hbrav 3y ago
  I think "wire only" means the hook catches while the wheels are still off the deck. I suppose that hard landing might have, in some ways, replicated the hard slam-down this would produce. Author, is that the case? Was the hard landing judged to have been a decent proxy for the wire-only arrestment?
  - bronson 3y ago
    Seems unlikely. One is slamming due to a heavy glideslope. Two is slamming due to a serious yank on the rear section. The airframe stresses and flight dynamics will be different.
    - euler_angles 3y ago
      Yeah, dynamics will be different, though caveat I am not a structures/loads engineer. I just don’t think anyone had the risk appetite to chance a test asset against a very difficult to achieve test point.
      - hef19898 3y ago
        It is also fair to assume the decision to not do additional testing of wire-only arrests was well analyzed by the respective engineering teams. Program management does not take decisions like this by themselves.
        euler_angles 3y ago
        Absolutely. We had a whole carrier suitability team full of people who lived and breathed this stuff. It was just my responsibility to make sure the aircraft instrumentation system got them the data they needed, at a high enough quality, to empower their analyses and decision making process.
- werrett 3y ago
  Based solely on the above description -- wire-only is when you don't have wheels on deck, also slowing the craft down.
jessriedel 3y ago
(BTW, the twitter link on your blog is mistakenly going to twitter.com. I think you meant to link to your account: https://twitter.com/the_engi_nerd https://twitter.com/the_engi_nerd Cheers!)
- euler_angles 3y ago
  Oh, thanks for the spot. Not sure why it's doing that...
  - euler_angles 3y ago
    Fixed