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  1. MechinNC

    Air India 787 crashes on take off

    If change of switch position was nefarious, intending to put the aircraft in the dirt, this is actually brilliant. This early in climb out, shutting down engines means that even with switch re-position 10s later, the re-light sequence would start (it did). But AC was descending and re-light...
  2. MechinNC

    Air India 787 crashes on take off

    I understand that a complete FADEC failure would take out the engine. That seems unlikely as there are two units per engine, and I think two channels per unit, with gen power dedicated to FADEC and associated engine controls from engine gearbox. My question is mostly that if other software...
  3. MechinNC

    Air India 787 crashes on take off

    Just a basic question from a non-pilot, non-aero engr: Say some computer decided to roll back power (and does this actually move the levers? I think it does..). Pilot notices levers pulling back and says heck no, I need power NOW. And shoves levers to max thrust. Who is in control at that...
  4. MechinNC

    Electric car ship fire.

    I do not think much if any cargo (cars) survived. Aero photos showed scorch marks on almost all decks.
  5. MechinNC

    Electric car ship fire.

    I do not see what the point was regarding a salvage attempt. Once that fire spread through out, the ship is a wreck. Steel warped and softened by heat, all wiring and piping burned up. Maybe engine, gennies and prop salvageable. Even those are not likely worth a tow to Paki or India. Maybe...
  6. MechinNC

    Air India 787 crashes on take off

    Gonna speculate a bit (it is simply how my mind works!!): With RAT deploying so soon, its signal to deploy was likely not due to dual engine complete failure. The engines seemed to be making some thrust as you could hear them running at low power (???) when the RAT was heard. Certainly NOT at...
  7. MechinNC

    Spain and Portugal power grid collapse | Report Released

    I agree that a big turbine set has lots of advantages due to inertia. But for grid stability that inertia can last maybe seconds unless the turbine is alive by burning fossil fuel or nuke. And that is inefficient if the power is not needed and only grid damping is needed. On utility scale, I...
  8. MechinNC

    Spain and Portugal power grid collapse | Report Released

    No, I read the whole thread and much more on this topic. Batts and inverters (might I stress, properly set up inverters) can do what ever a rotating machine could do to enhance grid stability. It is just that a rotating machine does this naturally without needing particularly good controls as...
  9. MechinNC

    Spain and Portugal power grid collapse | Report Released

    I would think a battery farm would be better at handling grid control than any sort of rotating machine. Probably cheaper and more efficient too.
  10. MechinNC

    FIU Bridge Update - New Bridge Has Broken Ground

    Why are bridge designers going for these goofy designs?? No backstays on the pilings? Why not? And those cable stays are not structurally necessary??? I am a true believer in "Form Follows Function". One look at the proposed new bridge (and the failed one!!) has my mind going WTF. 200ft...
  11. MechinNC

    Air India 787 crashes on take off

    In my mind possible that some sort of complete electrical failure caused the in-tank AC fuel pumps to quit. This would cause a RAT drop even before the engines spooled down completely and be triggered by loss of AC generation or loss of hydraulic pressure. The engines have gear driven fuel...
  12. MechinNC

    Root Cause Analysis - Steam Turbine

    I worked in a big steam plant a couple of decades ago. If we had trouble with our turbines that was beyond what we could do, we consulted or hired the turbine manufacturer (GE). Expensive, but they knew the machines.
  13. MechinNC

    The largest peacetime disaster in US Navy history...

    Navigating back then was not a perfect science. Celestial nav required clear skies. Get a few cloudy days and nights in a row and your dead reckoning can be pretty far off. In that case, officers need to err on the side of caution (as in keep farther off shore and slow down, etc). Wait until...
  14. MechinNC

    Tourist submersible visiting the Titanic is missing Part 2

    Not a structural engr here, but I have put a fair amount of thought into this. Some here seem to have a LOT of experience in structural composites, and I certainly respect that knowledge. But to this generalist, I came up with a few possibilities: 1. Non uniform distribution of stress in the...
  15. MechinNC

    Norway bridge collapse - Part 2

    Why use wood at all?? The steel or iron bridge lasted, what 100yrs (??). Seems foolish.
  16. MechinNC

    Tourist submersible visiting the Titanic is missing Part 2

    Yea, I know it did not have ribs. Just wondering if ribs would have made a better design.
  17. MechinNC

    Tourist submersible visiting the Titanic is missing Part 2

    I am no stress analysis type engr, but on that 5" thick CF cylinder in compression, are the stresses uniform throughout the laminate? I think not, but too lazy to research it. I know our Navy subs use ribs internal to the pressure hull. Wonder if this thing could have been built up with...
  18. MechinNC

    Tourist submersible visiting the Titanic is missing Part 2

    I read an interesting piece today in Vanity Fair. I'd post a link but I just burned up my free article. Now behind a paywall for me. A few interesting take-aways: 1. There were basically no substantial pieces of CF found in the wreckage. They picked up some shards, that is it. 2. Some of...
  19. MechinNC

    Tourist submersible visiting the Titanic is missing Part 2

    I could see water migrating into the CF hull, either through the sides protected with Rhino Liner (really??), or from the edges where the TI ends glued on. I do not think Rhino Liner has been tested to be non-permeable at 5000psi.
  20. MechinNC

    Bridge failure near Albany NY

    Fortunately could be a relatively easy fix. Cut out damaged section, fab new section (with proper reinforcement) and weld or rivet it in place. Could be done in situ. But who knows what the concrete already poured did. That was a lot of rebar on that concrete deck. Could see where the engr...

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