Subject: Number Eighty-Four in the Series--Republic F-84 Thunderstreak (10 of 13)

From: [email-masked]
Date: 28 Jul 93 16:29:04 GMT

>From [email-masked]

The F-84F had a somewhat sluggish climbing performance and its maximum 
speed fell off rather rapidly at higher altitudes.  In pursuit of 
better performance, the USAF asked Republic to see if their 
Thunderstreak could be adapted to the new General Electric J73 
turbojet.  This project was given the designation of F-84J.  

As a first step, two F-84F-25-REs (51-1708 and 1709) were taken off 
the production lines and adapted to the General Electric XJ73-GE-5 
turbojet of 8750 lb.st. or the XJ73-GE-7 of 8920 lb.st.  This 
larger, more powerful engine required that the fuselage of the F-84F 
be deepened.  These two modified aircraft were redesignated YF-84J.  

The first YF-84J (51-1708) was flown on May 7, 1954.  The increased 
power offered by the J73 engine enabled the YF-84J to achieve Mach 
1.09 in tests.  However, the USAF did not accept the type for 
production, since they felt that the costs involved in the change of 
engines on the production line would be prohibitive.  In addition, the 
Mach 1.25 F-100 Super Sabre was just beginning to enter service and 
seemed more than adequate to meet the USAF's needs for 
high-performance fighter aircraft.  Consequently, the second YF-84J 
(51-1709) was cancelled in June of 1954, before it could be flown and 
the F-84J program was cancelled in its entirety on August 31, 1954.  
  
Sources:

  Fighters of the United States Air Force, Robert F. Dorr and David Donald,
  Temple Press Aerospace, 1990.

  The American Fighter, Enzo Angelucci and Peter Bowers, Orion, 1987.

  American Combat Planes, Third Enlarged Edition, Ray Wagner,
  Doubleday, 1982.

  United States Military Aircraft Since 1909, Gordon Swanborough and
  Peter M. Bowers, Smithsonian, 1989.

  The Republic F-84F Thunderstreak, Ray Wagner, Profile Publications, 1966.

Joe Baugher		AT&T Bell Laboratories   	
2000 North Naperville Road      Naperville, Illinois 60566-7033