by Tommy H. Thomason

Wednesday, January 29, 2014

F4H/F-4 Topic Index

 The Ill-fated 1st Sage Burner (Robert F. Dorr Collection)

As it turns out, Kim Simmelink has done the work for me. See

I recommend that you take the time to review the posts on his blog.

Here are a couple that he didn't list:

Production F-111B Fuselage

Mark Nankivil has been scanning material from the Gerald Balzer collection and keeping me in mind when he comes across something that will be of interest to me. In this case, it was the McDonnell lines drawing for the production F-111B forward fuselage. McDonnell was involved with the F-111B program because they were the subcontractor for the crew escape capsule. When Grumman raised the canopy to improve visibility on approach for the production F-111Bs, McDonnell had to modify the capsule.

I had previously only had a few bits of data (fuselage length increase, windshield angle change, and height increase); a small and somewhat crude three-view drawing; and pictures of the sixth and seventh F-111Bs with the longer nose (but not the raised canopy) to work with. I also assumed that the capsule interface with the fuselage remained the same all around to minimize tooling changes. I was therefore surprised to see that Grumman, in addition to raising the canopy, had lowered the interface of the windscreen with nose, thereby further improving visibility over the nose. I had noted by reference to the pictures of the F-111Bs with the longer nose that they had lowered the radome slightly, which now makes even more sense.

On the two interim-production F-111Bs that flew, the upper side of the nose was modified from the production configuration to marry up with the forward bulkhead of the original escape capsule.

I'll note once again that the at-sea F-111B trials were conducted with an F-111B that did not have all the changes known to be forthcoming in the production aircraft (see As a result, any deficiency related to visibility on approach was already being corrected.

For more on the F-111B, see and and buy my monograph, available on Amazon ( or from Steve Ginter:

Sunday, January 12, 2014

World War II Navy Carrier Airplane Antennas

In the process of creating a post on F4U Corsair antenna alternatives (see and if you haven't looked at it very recently, it has changed), I decided that a more general post here might be of interest.

From the top, the high frequency (HF) radio antenna was a long wire (the lower the frequency, the longer the antenna needed to be for good transmission/reception). It was generally attached to a mast and the tip of the vertical fin or rudder to keep it away from the fuselage, with insulators at each end and a tensioner (either a spring or a rubber cylinder) at one end to keep the aerial taut. A lead-in wire was attached between the antenna and the fuselage, either at the far end, in the middle as shown here, or somewhere in between. Again, a ceramic insulator was provided at the fuselage entry point.

The HF antenna was also used to navigate by radio beacon or range and as a sense antenna for the direction finder. (The sense antenna was needed with early direction finders to resolve whether the needle on the instrument in the cockpit was pointing to or from the transmitter; otherwise, the pilot had to make one or two turns and fly the new heading for a minute or two to determine the way to the beacon.)

Going from left to right on the underside of the airplane, the ZB antenna was also used to determine which direction to fly to the carrier. An ordinary radio beacon could not be used since the carrier did not want to make a transmission that the enemy could home on. The YE-ZB system was implemented to provide an indication to the pilot as to which direction to fly to find the carrier, with the YE transmitter on the carrier sending out a coded signal to the ZB receiver (see

The IFF (Identification Friend or Foe) antenna was originally a pair of wires, one on each side of the fuselage, that led to the outboard leading edge of the stabilizer. When turned on, the IFF responded to a transmitted radar pulse with a much stronger return than the reflection of the pulse would be from the airplane itself. This enhanced blip on a radar scope indicated that the airplane was friendly and not a potential threat. The first IFF was British, installed on Spitfires in late September 1940 and subsequently on Seafires as evidenced by this photo.

The U.S. Navy had it installed on early F4Fs (see the post referenced above), F6Fs (shown here), and F4Us (see the post referenced above).
Note the rod antenna on the spine of the fuselage just above the entry point of the IFF antenna that will be discussed subsequently.

This "cheese-cutter" IFF antenna arrangement was subsequently replaced with a rod antenna, usually mounted on the belly of an airplane, as shown on the Avenger picture at the top of this post and here.

A radar altimeter was generally only provided on so-called all-weather aircraft. The antenna looked like an inverted "T".

Two were required, located ten or so feet apart, in this case on the horizontal tail of an F2H-4 Banshee.

One antenna was used to transmit a pulse and the other to receive. The time between transmission and receipt was used to calculate the height of the airplane above the ground or sea.

The Yagi array was the antenna for the earliest airborne radar. This one has presumably just been removed or is being functionally tested prior to installation.

This antenna had to be manually turned to the bearing of interest. The radar return indicated the distance to large objects, like ships or a coastline, in the direction that it was being pointed. To provide 360-degree coverage, one was mounted under each wing. Because of the workload and skill involved in pointing the antenna and interpreting the resulting return, this early radar was only installed on airplanes with a radioman who was responsible for operating it.

Not shown in the Avenger picture above is a VHF (very high frequency) antenna like the one mounted aft of the canopy of a Corsair in a rigid mast. (The forward mast is not an antenna, per se, but just a means of positioning the origination of the HF wire antenna above the fuselage.)

Another variation of the VHF antenna was a simple rod or whip like the later IFF antenna shown above but perhaps twice as long. It may have been the antenna on the spine of the fuselage in the F6F Hellcat picture shown above with the IFF wire antenna. The rigid mast reportedly provided transmission/reception over a broader range of frequencies than the rod antenna but not as good at the specific range of frequencies that the rod antenna was designed for.

After February 1943, the equipment involved was designated in accordance with the Joint Army-Navy Nomenclature System, abbreviated as AN. An example is the Mk III IFF, which was AN/APX-1. The first of the three letters indicated that it was for an Aircraft. The second, the type of equipment, in this case A for radio. The third, the purpose of the equipment, in this case X for identification or recognition. A dash number following the three letters further refined the designation down to a specific piece of equipment, generally in order of qualification in that particular grouping. The first radar altimeter was the AN/ARN-1, with R for Radio (not P for Radar as you would expect) and N for Navigation aid. An ARC was a Radio for two-way Communication. An ARR was a Radio with Reception only, with the AN/ARR-1 being the receiver for the YE-ZB homing system.

For an excellent illustrated description of similar equipment as used on the post-war Royal Canadian Navy Avengers, see

Monday, January 6, 2014

F-4 Phantom ECM Antennas

I was planned to expand my Tailhook Topics Draft post on F-4S ECM antennas (see but when I came across this one by Kim Simmelink, it was obvious that it would have been a waste of my time, even if I got it all right, which was unlikely: Note that he updates it from time to time and his blog lists other F-4 subjects of interest.

Sunday, January 5, 2014

Grumman A-6 Wing Fold Differences Part 2

Jim Rotramel has graciously taken the time to provide me with his photos and Grumman illustrations of the wing fold fairing on the top of the wing for the A-6 metal wing, A-6 composite wing, and EA-6B wing.

The A-6 metal wing fairing was a series of four exposed hinges and separate panels that either stayed fixed with the inboard section of the wing or rotated with outboard section. There also appears to be one or two hinged panels at the aft end of the fairing that opened for clearance (and an exposed component that might be the top of an aileron bellcrank).
The four hinges are in line with the locking lugs and tie into four wing spars in the inboard section of the wing. If you examine this picture of the left-wing fold area closely (the picture above is the fairing on the right wing), you can see the location of the hinges and some of the sections of the outboard upper wing skin that rotate around components in the upper fold-joint area.

The A-6 composite wing and EA-6B wing were slightly different in detail but similar in concept: the wing-fold joint was a rectangular open area covered when the wing was spread by what resembled a bi-fold closet door lying flat. This is a cross section of the A-6 composite wing-fold fairing.

The A-6 composite wing  and EA-6B wing fairings were slightly different when viewed from above, primarily at the aft end. This is a comparison of the left-hand wing-fold fairing with Jim's dimensions.

Jim also provided comparison photos of the outer pylons of the A-6 metal and composite wings when they were spread.

Wednesday, January 1, 2014

Grumman A-6 Wing-Fold Differences

This is another one of those works in progress. Note: For the very best book on the A-6, see

There were three different A-6 wings as distinguished by the wing-fold mechanization (there were some other detail differences among the bomber wings that I might get around to illustrating sometime):

Original - A-6A/B/C/D, A-6E Metal Wing, and EA-6A


A-6E Composite Wing

The original wing fold was characterized by vertically oriented lugs to hold the outer wing panel in place when it was extended; a small fairing on the lower surface of the wing that covered the upper outboard surface of the pylon; and a small, narrow fairing on the upper surface of the wing over the fold joint.
(Cropped from a picture by Norm Filer)
For a better picture of this wing-fold arrangement, particularly the lugs, see Howard Mason's pictures here;

For a closeup picture of the fairing over the A-6 metal-wing fold joint other than the EA-6B's, see

The EA-6B used the same wing-fold actuation arrangement as the basic A-6 wing (an idler driven by two actuators, one in the inboard wing section and one in the outboard wing panel) but the wing-lock lugs were now horizontally oriented. I don't know the reason for the change, but it must have been compelling. Note that the wing-lock actuators are now oriented vertically, which required the addition of a large fairing on the outboard pylon (it covers the aft-most wing-lock actuator).
Here are two more pictures that illustrate the Prowler wing fold area. Note the small "shelf" on the forward section of the fairing on the pylon required to close a gap in the lower surface of the outboard wing panel. It's also evident that because the lugs and mating forks are horizontal, the lower surface (which is facing up in this picture) of the lug is slightly beveled or tapered so it can slide into the gap between the mating fork on the inboard side of the wing fold (those also appear to be angled slightly upward).

The fairing on the upper surface of the wing was much wider on the EA-6B than on the original wing.

The A-6E composite wing fold had horizontally oriented wing-lock lugs like the EA-6Bs but they were slightly different in configuration; the major change was the substitution of a rotary actuator  for the two linear actuators and idler link of the A-6 metal wings. There was a large fairing on the outboard pylon like the EA-6B's but there was no gap in it.
This Graeme Molineux picture provides much more detail.
 For another picture of the wing fold joint and more of this A-6E displayed on Midway, click HERE.
 You should also explore Graeme's web site:

The fairing over the fold joint on the upper surface of the wing was very similar to the EA-6B's but not identical. See Part 2,

If anyone has better pictures of any of these wing-fold areas, I'd be happy to substitute them.