Wednesday, November 20, 2013

Phantoms that never were built… RF-4M

In 1957 the British Secretary of State for Defense, Duncan Sands, presented a white paper which called for the elimination of manned aircraft in favor of missile systems.  To compound matters, the Royal Navy was chosen as the best means to deliver these missiles which would be submarine-based ICBMs and tactical weapons delivered from their aircraft carriers.  This left the British Aircraft Industry and the Royal Air Force (RAF) with just one aircraft project on the books, a replacement for the venerable Canberra.  This resulted in the TSR2 project which, after spending 200 million pounds in development, was canceled and the prototypes relegated to museums and the scrap yard.
The RAF needed a multi-purpose fighter, one which could perform the duties of the aging Hunter, Canberra, and Lightning aircraft currently in service.  The Royal Navy had already given up waiting for the V/STOL P.1154 which would not be available for 6 years (eventually itself canceled), and had decided to move ahead with an Anglicized Phantom II to be known as the F-4K (or Phantom FG Mk.1).  The RAF needed an aircraft which would handle Interdiction, Ground Attack, and Reconnaissance roles.  Since the Royal Navy had already chosen the Phantom, the RAF realized (and so did the bean counters in the government) that they could get this very capable aircraft and spread the cost of Anglicizing the aircraft over a larger number of airframes.  Thus the idea for the F-4M (or Phantom FGR Mk.2) was born.

McDonnell had approached the RAF before with Phantom proposals to meet their needs.  In 1960 they had proposed model 98CJ (proposed as F-4H) which was essentially an F-4B with some modifications for the RAF.  It was to be powered by Rolls Royce RB-168 engines with cartridge starters, dual controls for transitional training, the shipboard catapult, wing fold, and arresting gear was to be removed and replaced by a lighter, non-retracting tail hook for emergency use, and increased internal fuel provisions.  Then in 1964, McDonnell proposed model 98EO (proposed as F-4E) which was essentially the F-4D with Rolls Royce RB168-25R engines.

So when the RAF showed interest, McDonnell was quick to give them a proposal.  On 21 January 1965 the specifications for the model 98GN (proposed as the F-4M) was finalized and given to the RAF, which was essentially the same as the F-4K that the Royal Navy had ordered, with the removal of some Navy specific equipment like the extending nose gear strut.  This resulted in an order for 150 aircraft.

One very interesting proposal came out of the RAF’s requirement for the ability to use the phantom to replace the Hunter and Canberra in the reconnaissance role.  Britain could not afford (or chose not to purchase) a dedicated reconnaissance version like the RF-4B or -4C.  But in McDonnell Report No. B617, dated 1 August 1966 and titled The Royal Air Force Phantom II, McDonnell showed two options to fill this role.

The first option was a centerline pod which was about the size of the 600gal centerline fuel tank.  It was proposed that all the F-4Ms be built with the capability to use this pod.  The advantages of this system were that all the equipment could be moved from one aircraft to another as needed, repairs to the equipment could be performed without taking the aircraft out of service, and the aircraft would keep its full air-to-air capability.  The disadvantages were that the range would be reduced since there would be no centerline fuel tank, aircraft performance would be somewhat affected (although not much more than the centerline tank), and the aircraft, which already had very little room for added equipment, would have to have accommodated long cable harnesses to connect the pod to the newly added equipment for the cockpit and systems.

The second option McDonnell proposed was for a modification of the F-4M airframe to house the reconnaissance equipment internally.  This was model 98HT (proposed as RF-4M) and would add 2.65 feet just aft of the radome to house the cameras.  While this option would have increased range because it would be lighter than the F-4M with the recce pod, and it was able to carry a centerline fuel tank, this option was less desirable to the RAF because only the aircraft that were modified could fulfill the reconnaissance role; the modification would be more costly than the first option and thus fewer aircraft would be purchased with this option. Ultimately the modified aircraft would be less versatile since the FCS (fire control system) and AIM-7 Sparrow capability would be removed to make room for the reconnaissance equipment.  I assume that the RF-4M would retain its IR AAM capability.

Ultimately, due to the higher cost of the Anglicized version of the Phantom and pressing budgetary concerns, the RAF order was ultimately reduced to 116 aircraft and they chose to go with the EMI/McDonnell reconnaissance pod so that all the aircraft would be able to perform any task including reconnaissance.

  1. McDonnell Report B617, dated 1 August 1966
  2. McDonnell List of Proposed Models, dated 1 July 1974
  3. Aeroguide 13 - McDonnell Phantom FG Mk.1 & FGR Mk.2, by Roger Chesneau

20 November 2013 - Original Post

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