by Tommy H. Thomason

Tuesday, June 11, 2013

Blue Whales

Some have expressed interest in building the new Trumpeter A3D-2 kit as a blue Whale.
Note the all-blue landing gear and the red edge to the tail-wheel door but no other doors.

The XA3D that flew for the first time on 28 October 1952 was painted overall gloss sea blue. So was the first production A3D that flew on 16 September 1953. At the time, however, the Navy was evaluating other color schemes, having decided that dark blue was too visible against cloud cover for antiaircraft gunners. It also increased the thermal effect of an atomic bomb blast.

An all-metal scheme was given an operational trial because it reduced the visual signature at high altitude as well as weighing and costing less. A little over 100 fighters were deployed that were basically unpainted. This approach proved unsatisfactory from a corrosion control standpoint.

In February 1955, the Bureau of Aeronautics decreed that carrier-based airplanes would be painted in a nonspecular light gull gray and glossy insignia white scheme. Surfaces viewed from above, except for the elevators and ailerons, and the side were to be gray; those viewed from the bottom were to be white. The elevators and ailerons were to be white on both sides since their skins were relatively thin and therefore more susceptible to thermal damage. For some reason there was no such concern about the rudder or the flaps so at first the former was to be gray and the latter were to be gray on top, although there were exceptions.

It understandably took some time to implement a change like this. For ongoing production, the Navy had to request a contract change proposal. The contractor reviewed the requirement and created documentation: engineering drawings, process and paint specifications, and manufacturing paperwork. This was used to estimate the cost or savings of the change and prepare the proposal. The Navy then had to review and approve the proposal package and negotiate the contract change with the contractor before it could be implemented, although a change was sometimes authorized before the cost was agreed to.

The first A3D-1s were retained at Douglas for flight test. Six or so were subsequently assigned to the Naval Air Test Center for service acceptance testing. Some of these were instrumented, which made it likely that they would be returned to Douglas for follow-on development.

Another six or so were assigned to the Fleet Introduction Program, which provided for familiarization and training of squadron pilots and mechanics on a new airplane during an intensive two months of flying. The FIP airplanes were also painted blue. It appears that some or all of these were subsequently ferried to VAH-1 at NAS Jacksonville on 31 March 1956 to speed its transition to operational status. (Two were reportedly assigned to VX-5 at China Lake to begin weapon delivery qualification.)
 
The A3D-1s that were modified by Norfolk to be A3D-1Qs for electronic reconnaissance were almost certainly blue originally but they were repainted gray/white before delivery to the VQ-1 squadrons. (Chuck Huber reporsts that at least one A3D-1Q was delivered to VQ-1 still glossy Sea Blue.) For more on the A3D-1Qs, see http://tailhooktopics.blogspot.com/2013/06/a3d-1q-notes.html

My guess is that most if not all of the 50 production A3D-1s were originally painted blue (so were at least the first four -2s*). However, the first one delivered to VAH-2 in April 1956, BuNo 135440, was painted gray/white. Nevertheless, at least one of the subsequent VAH-2 A3D-1s was still blue like the first VAH-1 Whales.

Exemplifying the sporadic nature of the changeover, A3D-1 BuNos 135408 and 411 that were used for at-sea qualification by NATC aboard Forrestal in April 1956 had a gray/white fuselage, inboard wings (including engine pylons and nacelles) but blue outboard wing panels/ailerons, flaps, upper fin, and rudder.


Four A3D-1s were loaded aboard Shangri-La in late August 1956 to promote the airplane’s capability. Two, probably assigned to VAH-2, were launched on 1 September off Mexico for a flyby at the Oklahoma City Air Show and return to NAS North Island. The other two, probably VAH-1’s, were launched off the Oregon coast on 2 September for a flyby at Oklahoma City and a subsequent landing at NAS Jacksonville. Note that three of the four were blue more than a year after the color-scheme change was announced.

Only two squadrons, VAH-1 and VAH-3, actually deployed with the A3D-1. Six VAH-1 Skywarriors were reportedly aboard Forrestal for its no-notice sortie to the Mediterranean in November 1956 as part of America's response to the Suez crisis. At least four, and probably all six, were gray/white.
(Four were the last of the first production lot of A3D-1s, the last of which flew in June 1955; these were all flown directly to Norfolk for modification after acceptance at Douglas.)
 USN via Ken Killmeyer, USS Forrestal Association Historian

Chuck Huber reports that in addition to the six VAH-1 A3D-1s on Forrestal during the Suez Crisis in '56, the other six were on Saratoga - 1st operational cruise for both super carriers.
 
VAH-3 deployed with A3D-1s aboard FDR from July 1957 to March 1958. By this time, the changeover to the gray/white scheme was complete for A3Ds, at least in operational units.

The second lot of -1s and the first few lots of -2s were almost identical externally. The major changes were an uprating of the J57 engine and a structural beef up. However, there were detail differences between the first production lot of 12 A3D-1s (BuNo 130XXX) and the second lot of 38 A3D-1s (135YYY). The first -1s did not have the wing spoilers with two exceptions, 130357 and 359, or the drag chute capability. The catapult hooks were located on the fuselage about halfway back along the bomb bay (which was six inches shorter) instead of just ahead of the bomb bay**. A set of steps leading up from the left main landing gear was provided for access to the top of the airplane. Not all were equipped with the anti-buffet fence ahead of the bomb bay. All appear to have been completed with the fin-tip radome but at least some had it replaced with the plain fin tip after delivery.

Some corrections also have to be made to the Trumpeter A3D-2 kit for it to accurately represent a late A3D-1 or an early A3D-2. These include the deletion of the inflight refueling capability, gluing the entrance door closed or modifying it to represent the Bomber door, redoing the main wheel hubs so they are flush on the outboard side, filling in the engraved lines for the CLE wing slats inboard of the engine pylon and modifying those outboard of it, adding equipment to the bombardier’s position, and correcting the pilot’s seat. Some of the antennas shown in the instructions have to be left off.

For more on some of these corrections, see:
http://tailhooktopics.blogspot.com/2013/05/trumpeter-148-a3d-2-skywarrior.html
and
http://tailspintopics.blogspot.com/2013/06/a3d-3-skywarrior-wings.html

Interior Colors:
 Cockpit: The instruction to change from black/interior green to black/dark gull gray was issued on 25 March 1954. This suggests that that at least the cockpits of the first several A3D-1s, and probably all of them, were basically black except for the floor, which would be interior green.
Wheel wells: Sea blue (at least one gray/white A3D-1 had blue wheel wells)
 Bomb bay: At this point bomb bays were still to be painted interior green.

*At least the first four A3D-2s, BuNos 138902-5, were painted overall blue. The first one (for some reason, 138903) flew in August 1956 more than two years after the changeover and months after the repainting of the first -1s had begun. However, 138905 had been repainted in the gray/white scheme some time before it was photographed in flight on 4 January 1957.

**It was originally thought that the angle of attack desired for a catapult launch was best achieved by hooking it up so the pull was applied behind the aircraft’s center of gravity, forcing the nose up and the tail down onto the tail wheel provided (tail-down launch). However, it was determined that moving the hooks forward so the nose was pulled down when the catapult stroked resulted in less drag during the launch and the compression of the nose gear strut. At the end of the stroke, the nose gear strut would re-extend, pushing the nose up to the desired angle of attack just before the A3D crossed the bow (level launch).

Sunday, June 9, 2013

A3D (A-3) Skywarrior Wings

I've revisited my original drawing comparing the original A3D wing and the Cambered Leading Edge (CLE) A3D wing introduced partway through production. See http://tailspintopics.blogspot.com/2010/09/mighty-skywarrior.html for applicability and some details.
(Note that there wasn't perfect consistency among the various Douglas drawings that I used to create the above illustration, so it shouldn't be used to correct trivial differences on the Trumpeter or Hasegawa kits.)

Some configuration details to watch out for:

The most inboard CLE slat did not extend as much as the outboard slats.

There was a small fairing added on the inboard side of the engine pylon when the CLE wing was introduced.

The A3D slats were aerodynamically actuated so they opened automatically as the airplane was slowed to approach speed (strictly speaking, as angle of attack increased). On the original wing, the most outboard slat closed due to gravity when the wings were folded; according to the flight manual "the outer wing inboard slats on each wing are mechanically extended when the wings are folded" in order to avoid damage to the wing and that slat.

On the CLE wing, for some reason, both slats on the folding wing panel were allowed to close when the wings were folded.

 Note that the ailerons drooped downward on both the original and CLE wings.

Saturday, June 1, 2013

Things Under Wings: F4H (F-4) Phantom External Fuel Tanks

6 June 2013: Revised 600-gallon and McDonnell 370-gallon tank illustrations in accordance with McAir drawings provided by Mark Nankivil

3 June 2013: Updated with additional pictures and information.

The McDonnell F4H Phantom was delivered with unique external tanks, a big 600-gallon centerline tank and somewhat smaller but still unusually large 370-gallon wing tanks. The two General Electric J79s enabled it to lift a heavy load but required a lot of fuel, particularly in afterburner.


The 600-gallon tank with the "long" pylon fairing (which suggests that there was a short one; I don't know what it looks like yet):

Forward is to the left. Note that there are two small brackets on the aft part of the tank mounted at a 45 degree angle to vertical. These functioned as sway braces (and probably insured that the tank departed cleanly when jettisoned) because when the tank was attached, they were set into brackets that were mounted on small access doors on the belly of the F-4.
Craig Kaston provided this closeup of the aft sway brace (the hose provided the air to start the J79).
This Bill Spidle picture shows how little clearance that was between the 600-gallon tank and the fuselage.

There were supplier or at least design changes to the 600-gallon tank. (McDonnell short fairing, nestable, and welded; and Royal Jet are some of the configurations listed in the flight manual; the drawing above is the "welded" version) Note the flange on the lower left side of this one. I await comments and further information...
At some point, some operators of the F-4 (for example the USAF but not the Navy/USMC) adopted the F-15 610-gallon tank that did not have this aft sway brace arrangement and was not mounted at a nose-down angle.

The first 370-gallon tanks were provided by McDonnell. They can be distinguished from the subsequent Sargent Fletcher tanks by 1) the continuous increase and then decrease in cross section and 2) the flange on both sides of the tank where the upper and lower halves were connected together.
I'm pretty sure that this tank was 240 inches long and about 26 inches in diameter based on scaling a McDonnell stores drawing provided by Mark Nankivil.

Strictly speaking, the pylon and McDonnell tank were separate items, unlike the later tank. I had wondered why there were no sway braces involved or gap between the pylon and the tank (there was a small gap between the pylon and the wing—see picture in the discussion of the later tank) until Rex Droste provided this illustration, which shows that the tank was bolted to the pylon, not simply hung from it:
Installation of the tank on the pylon was obviously not as simple as hanging it and connecting the fuel and pressurization lines...

As you can see from the above picture and the following one, the forward mounting flange of the pylon was not symmetrical.
The reason was undoubtedly the need to transfer the weight of the tank directly into a wing spar, which was swept. Note that the outboard flange in the picture of the lower wing surface appears to be smaller than one in the illustration, possibly one of the differences associated with the later 370-gallon tank.

The later tank was supplied by Sargent Fletcher. You will see statements to the contrary (the early tanks were Sargent Fletcher and the later tanks, provided by McDonnell) in print and on the web but I'm all but certain of this.

The later tank is distinguished by having a constant cross section for much of its length and only one flange, which was on the lower left side of the tank.

A view of the right side of the Sargent Fletcher tank, showing that there is no flange. (The line on the tank is a painted pin stripe.)

The shape of the aft lower side of the pylon had to be different due to the changed shape of the tank and in this case, the pylon and the tank were a single unit.
Craig Kaston provided the following picture of an installed Sargent Fletcher pylon/tank and noted that there was a gap between the pylon and the wing.

The McDonnell tanks were on the first operational F4Hs. I'm not sure when the changeover to the Sargent Fletcher tank was made, but I vaguely remember there being two different tanks while I was a flight test engineer for McDonnell in 1966. According to an illustration of Sargent Fletcher history, it began delivering F-4 tanks in the late 1960s, roughly corresponding to the changeover in production at McDonnell to the F-4J. Rex Droste reports that there are dated pictures of the McDonnell tanks being used as late as August 1974, at least on USMC F-4s. I'm sure that there was nothing fundamentally wrong with them other than they were probably more expensive than the Sargent Fletcher. As a result, they would have been used until they were no longer economical to repair.

Note: For a possible third version of the 370-gallon tank, see http://tailspintopics.blogspot.com/2014/02/f4hf-4-370-gallon-external-tank-redux.html