Subject: New Fighter Series--McDonnell F-4 Phantom (29 of 50)

From: [email-masked]
Date: 14 Jun 94 16:23:12 GMT

>From [email-masked]

The F-4X and RF-4X were proposals for advanced F-4E derivatives 
designed by General Dynamics to carry the HIAC-1 long focal length 
camera as part of *Project Peace Jack*.  This project was a joint 
Israel-USAF study for an advanced photo-reconnaissance aircraft 
capable of Mach 3+ performance.  

The HIAC-1 camera was an advanced high-altitude reconnaissance camera 
that had a focal length of 66 inches which offered unparalled 
resolution at extreme ranges The HIAC-1 camera was originally so large 
and heavy that it could only be carried by the Martin/General Dynamics 
RB-57F.  However, later versions were sufficiently slimmed down so 
that they could potentially be carried by smaller aircraft such as the 
F-4 Phantom.  

Israel had always wanted the HIAC-1 camera for its own use in keeping 
track of its Arab neighbors, but its requests had always been turned 
down.  However, in 1971, US attitudes towards export of the HIAC-1 
camera changed and approval was given for the development of a pod 
(designated G-139) which could carry this camera on the belly of a 
Phantom.  The prototype G-139 pod was over 22 feet long and weighed 
over 4000 pounds, and was first tested on an RF-4C in October of 1971.  

Unfortunately, the G-139 was still so large and bulky that the 
performance of the Phantom when it was carrying the pod was 
unacceptably poor.  The *Peace Jack* project originated in an attempt 
to improve the performance of the Phantom when carrying this camera.  
Both the USAF and the government of Israel contributed funds for the 
project.  

Rather than trying to slim down the reconnaissance pod, the original 
goal of the General Dynamics team was to improve the performance of 
the Phantom that was carrying it.  The improved performance was to be 
obtained by using water injection for pre-compressor cooling, which 
would provided increased engine thrust at high altitudes.  A similar 
system had been used successfully in the past in various F-4 record 
attempts.  The water was to be contained in a pair of gigantic 
2500-gallon tanks which were to be attached conformally to the 
intersection joints of the fuselage spine and the engine nacelles.  
The water injection system promised to give a 150 percent increase in 
engine thrust at altitude.  In order to accommodate the increased 
engine thrust that would now be available, new air intakes had to be 
designed.  The area of the intakes was to be made much larger and they 
were to contain a sophisticated system of internal cowls, splitter 
plates, vortex generators and bleeds.  With the new intakes and the 
water injection system, it was anticipated that maximum speeds of up 
to Mach 3.2 and cruising speeds of up to Mach 2.7 could be attained.  
The project came to be known as the F-4X, although this was not an 
official USAF designation.  

Israel was clearly very interested in the F-4X, as it promised a a 
performance which would approach that of the USAF's SR-71.  This would 
enable it to fly unimpeded anywhere it wanted to.  However, the 
advanced performance of the F-4X clearly made it a possible candidate 
for a new interceptor.  Consequently, the US State Department became 
more than a little worried about the export of such advanced 
technology overseas, since it promised to give Israel a potential 
interceptor which was more capable than anything currently in the US 
arsenal, one which might one day pose a threat to the SR-71.  In 
addition, the Air Force was itself rather nervous about the F-4X 
project, since it might threaten to divert support away from the F-15 
program which was just then getting underway.  As a result, the State 
Department decided to disallow export of this technology to Israel.  

This ordinarily would have been the end of the game.  However, in the 
meantime, Israel had expressed concern about the amount of aerodynamic 
drag produced by the pod carrying the camera.  In response to these 
concerns, General Dynamics decided to relocate the HIAC-1 camera to 
the nose, displacing the AN/APQ-120 radar.  The project was 
redesignated RF-4X.  The removal of the interceptor capability seems 
to have reassured the State Department, and Israel was once again 
allowed back into the *Peace Jack* program.  

An ex-IDFAF F-4E (USAF serial 69-7576) was delivered to General 
Dynamics in December of 1974 to act as a mockup for the RF-4X.  The 
nose was recontoured on the starboard side only, and a paper-mache 
coolant tank was fitted to one side of the upper fuselage.  New 
intakes with revised variable ramps were fitted.  However, in the 
meantime, the Air Force began to have second thoughts about the 
project, still fearful of the impact of the RF-4X on the F-15 project 
and nervous about the safety and reliability of pre-compressor 
cooling.  The USAF withdrew from the project shortly thereafter, 
forcing Israel to go it alone.  By itself, Israel could not afford to 
continue the project, and the RF-4X program quietly died.  

The idea for the nose-mounted HIAC-1 camera was later revived to form 
the basis of the F-4E(S), which was first applied to F-4E 69-7576.  

Sources:

  McDonnell Douglas Aircraft Since 1920: Volume II, Rene J.
  Francillon, Naval Institute Press, 1990.

  McDonnell F-4 Phantom: Spirit in the Skies.  Airtime Publishing, 1992.

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

Joe Baugher				AT&T Bell Laboratories
1000 E. Warrenville Road		Naperville, Illinois 60566-7013