Saturday, February 23, 2019

The Evolution of Door 19 on the F-4

Ok, I know I get a bit anal with some of my research, but here is what I have found on the evolution of Door 19 on the F-4s. There seem to be six major configurations of the door that covers fuel cells 1&2 (there are many subvariations for the addtion of antennas).

Variation 1

This version was used on BuNos 145307 through 145317, or the F4H-1s that had the straight canopies.  There were two panels (panel 19 and panel 20) mounted with a lot of screws (panel 19 had no less than 72 screws used to mount it), no hinges found here.  The ADF antenna was a large rectangular-ish shape.
Panel 19/20 Variation 1

Variation 2

This version was introduced with the raised canopies on the remainder of the F-4As BuNos. 146817 through 146819 & 148255 through 148275. Still mounted with a lot of screws (panel 19 now had only 48 screws), and still split into two panels (panel 19 and panel 20), it now sported a round IFF antenna. (There were exceptions with 146820 through 148254 getting Variation 3)
Panel 19/20 Variation 2

Variation 3

As this area became necessary for added electronic equipment the area underwent a transformation.  Gone were the multitude of screws, being replaced with much fewer (49) Airlock Fasteners (according to the F-4B/J Plane Captains handbook). With the addition of a hinge, the panel became a door.  The door was split into three sections connected with hinges (I would imagine this was so equipment could be accessed without opening the entire door?) This version was first seen on F-4As  146820 through 148254 and then reappeared on the production F-4Bs starting with BuNo. 148363.  At some point, this door was dropped in favor of Variation 4 which was first used in the Navy on the RF-4Bs. Looking at the Plane Captains handbook, it seems to indicate that this was used on all F-4B/Ns with the change coming with the F-4J.
Door 19 Variation 3

Variation 4

With the introduction of the RF-4Bs, (well, actually the USAF Versions but they used Variation 5) the door underwent another transformation.  Gone were the hinges and the door became one single door.  (Don't know when the non-RF models converted over to this variation.)  Also, the Plane Captains book indicates a change to (49) Quick Release Fasteners (also called barrel nuts) for the RF-4B, but still indicates Airlock Fasteners for the F-4J. But in an early F-4C handbook they are referred to as Airlocks as well so I wonder if it was just a difference in the identification and that they were never Airlock Fasteners and always the barrel nuts?
Door 19 Variation 4

Variation 5

Ok, not much of a variation, but this was used on the USAF F-4s.  The main change is the signal light was moved from the spine to this door to make way for the inflight refueling receptacle. I have drawn the IFF antenna larger because the photos I have seem to indicate that the USAF used a larger antenna, but I could be wrong. The Air Force used 43 Quick Release Fasteners (barrel nuts) to secure the door.
Door 19 Variation 5

Variation 5a

This variation found on USAF F-4Es includes the SST-181X rendezvous beacon on a round mounting plate just to the right of the IFF antenna.
Door 19 Variation 5a
NOTE: The SST-181X Rendevous  Beacon was part of the Project Sky Spot equipment installed in aircraft during the War in Vietnam. After the war, most of these beacons were removed and cover plates were installed in their place. 

Variation 5b

This variation again found on USAF F-4Es has the SST-181X rendezvous beacon mounted on a tear-drop mounting plate.
Door 19 Variation 5b

Variation 5c

This variation was found on some F-4C and F-4D aircraft during the War in Vietnam.  The SST-181X rendezvous beacon was installed aft of the signal light and before the hinge on the centerline of the door.  (I have seen one exception, F-4C 63-7581 which appears to use variation 5a, but the picture I have is poor and it may be another antenna entirely.)
Door 19 Variation 5c

Variation 6

This variation was found on USAF RF-4Cs.  For some reason, the IFF antenna and the signal light were both moved aft on the door.
Door 19 Variation 6


Where do we go from here? Well, there are still some more different antenna mountings on the door which need a bit more research.  But I do plan on updating this page as I understand the additional variations better.

References:

  1. Drawings (c) by Kim Simmelink
  2. Information gathered from NAVWEPS 01-245FDA-3-1 and photos.
  3. Information from Scott Wilson

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