Iron Birds

Static test airframes, or more commonly called, “iron birds” are partially built, non-flying airframes or old formerly flying airframes that are used by agencies and manufacterers to test either the strength of than airframe, various design components or aircraft subsystems (avionics, flight control, engines, etc).

The iron birds used for strength testing are typically full scale representations of the aircraft that are rigged to gaint gantry cranes with weights and strain gauges attached. See the pic:

Lockheed's F-35 test airframe installed on gantry cranes with strain gauges.

Lockheed’s F-35 test airframe installed on gantry cranes with strain gauges.

Once installed on the cranes the airframe is literally pulled and pushed to properly simulate all the aerodynamic forces that the aircraft will encounter throughout it’s flying career.  Often the iron birds are tested till destruction.

This is a VC-10 undergoing wing fatigue testing. Note the bending wing.

This is a VC-10 undergoing wing fatigue testing. Note the bending wing.

Some iron birds are formerly flying airframes that have accumulated too many flying hours and are no longer consider safe to fly. These aircraft are typically stripped of most equipment (engines mostly) and used to test various aircraft subsystems in support of other programs.

This NASA's F-8 Crusader iron bird that was used to test software for NASA's Digital Fly-By-Wire program in the 1960s,

This NASA’s F-8 Crusader iron bird that was used to test software for NASA’s Digital Fly-By-Wire program in the 1960s,

 

As the latest example of NASA's iron bird, this is an F/A-18 Hornet used by NASA to support many of the F/A-18 test programs.

As the latest example of NASA’s iron bird, this is an F/A-18 Hornet used by NASA to support many of the F/A-18 test programs.

Iron birds aren’t limited to NASA. The US military also used them for the same purposes.

This B-2 at the National Museum of the USAF was never an actual flying airframe. This "aircraft" appropriately named "Fire and Ice"was used for fatgiue and climatic testing.

This B-2 at the National Museum of the USAF was never an actual flying airframe. This “aircraft” appropriately named “Fire and Ice”was used for fatgiue and climatic testing.

A close up of "Fire and Ice's" nose gear door.

A close up of “Fire and Ice’s” nose gear door.

You can learn more about that particular aircraft here.

As an aside, old airframes are also typically used as maintaince trainers in the military. These are called ground instructional airframes:

images 080613-F-1322C-001

 

 

4 Comments

Filed under Aeronautical Engineering, Air Force, Airplanes, Flight simulation, Flying, Naval Aviation, Other Stuff, Outside the Box, USAF

4 responses to “Iron Birds

  1. Old AF Sarge

    Good stuff Spill. It’s nice when we old dogs can still learn new things.

  2. Bill Brandt

    I worked for Cessna Aircraft in Wichita for all of 6 months in the early 80s – got laid off due to th economy and companies walking away from their (then) $90,000 deposits for a Citation.

    But it was an interesting time.

    At the time, they were in the process of certificating the Citation III – the first of their Citations that really had true passenger jet speeds and transcontinental ranges.

    (as an aside the ATC controllers would jokingly refer to the original Citation as the “Near Jet”.)

    Whenever we went to the company cafeteria for lunch we would walk though the experimental hanger – seeing stuff that aviation magazines were writing about.

    Towards the ceiling was a Citation III wing – being flexed automatically on a timed interval by hydraulic jigs – to simulate 1000s of hours of flight.

  3. Test articles pop up in the oddest places. For years this one has popped my neck every time I drive by it on Interstate 30 near Leary, Texas. Go here on Google Earth to take a look:
    33°27’59.51″ N 94°12’47.93″ W

    It’s an F-111 sitting in someone’s junk yard. Go figure.

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