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View Diary: Air-Minded: the C-130 Replacement that Wasn't (114 comments)

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  •  Nothing humble about the C-130J (14+ / 0-)

    Before I left civil service for the private sector, I worked for the Air Force Engineering & Technical Services (AFETS) as the C-130J avionics SME.  Wonderful plane to work on.  It is actually a stretch C-130--the cargo bay is longer by about 11 feet.  The cargo handling system is controlled from a GUI computer display located in the aircraft galley.  It has a glass cockpit and all of the avionics is databus.  

    The engines are, of course, sweet.  Turboprops have one difficult-to-beat attribute:  instant power when the throttle is advanced.  A turboprop is already running at 100% and speed changes are accomplished by changing prop blade pitch.  By comparison, turbofans accelerate by increasing the speed of their relatively heavy stators and rotors, which means the engine is less responsive to throttle changes.

    Another turboprop attribute is how efficiently it reverses thrust.  This is accomplished by reversing the prop blade pitch, which reverses 100% of the engine output.  Turbofans use a clamshell door to reverse some of the engine airflow, which is inefficient and loud, and the system is high maintenance.  Turboprop reversing is so efficient that when a C-130J reverses its props on landing, it looks as if the plane landed in just sticks to the runway and stops.

    I left AFETS because I got bored after 25 years of aircraft maintenance and the C-130J was reliable enough to not be much of a challenge.  Now I work in the marine industry but I still miss aircraft.  I had lunch at a local airport today so I could hang out and watch the flying.

    "First they ignore you, then they laugh at you, then they fight you, then you win". Mohandas K. Gandhi

    by DaveinBremerton on Thu Nov 15, 2012 at 09:50:44 PM PST

    •  Oops, the above should say "compressor and fan" (6+ / 0-)
      Recommended by:
      JeffW, kurt, terabytes, weelzup, Simplify, chimpy

      I actually wrote "stators and rotors" which is a flashback to my J-57 turbojet days on the KC-135A.  Wow, I must be tired tonight.  Turbofan engines use a small jet engine as a compressor to run a very large, free-spooling fan.

      "First they ignore you, then they laugh at you, then they fight you, then you win". Mohandas K. Gandhi

      by DaveinBremerton on Thu Nov 15, 2012 at 09:56:19 PM PST

      [ Parent ]

      •  Need for instant power (3+ / 0-)
        Recommended by:
        terabytes, xaxnar, DaveinBremerton

        That attribute is a huge reason why they are used as the workhorse of arctic service [north and south].  Landing and takeoff from some of the places near the poles is tough but instant power when things go screwy is a big help.

        For example see post below this one.

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