What is this large engine doing on a B52?
Testbed Aircraft Cameos


  As a young engineer in the 1960s at Pratt &amp; Whitney Aircraft (now
  UTC’s Pratt &amp; Whitney) in East Hartford, Connecticut, I was involved
  (along with many others) in the development of their 44,000 pound
  thrust (lbt) JT9D turbojet, which powered the first Boeing 747 jumbo
  jet aircraft[ Display footnote number: 2 ]. Because of its then
  ground-breaking large fan diameter (new for the 1960s), P&amp;WA had to
  use a U.S. Air Force Boeing B-52 as a testbed. The Stratofortress,
  with its high wing, allowed the JT9D to be mounted with adequate
  ground clearance for takeoff and landing. In Figure 1, the P&amp;WA
  testbed aircraft is shown landing at the Windsor Locks, Bradley
  International Airport, after a test flight, with a JT9D engine
  replacing two TF-33 inboard engines on the right wing of the
  eight-engined B-52.
  
  The B-52 continued as a P&amp;WA testbed aircraft until 1981, even after
  being damaged in its hangar by a violent tornado that raced through
  Windsor Locks in 1979. Pratt &amp; Whitney more recently used two Boeing
  747SP aircraft for testbeds, to flight test their new geared fan jet
  engines.