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.

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 http://thanlont.blogspot.com/2012/12/grumman-6-intruder-history.html

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

EA-6B

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; http://www.primeportal.net/hangar/howard_mason/a-6e/

For a closeup picture of the fairing over the A-6 metal-wing fold joint other than the EA-6B's, see http://tailspintopics.blogspot.com/2014/01/grumman-6-wing-fold-differences-part-2.html

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: http://www.grubby-fingers-aircraft-illustration.com/

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, http://tailspintopics.blogspot.com/2014/01/grumman-6-wing-fold-differences-part-2.html.

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

Photo Gator

When the Navy needed to replace its existing fleet of light, carrier-based photo-reconnaissance airplanes, it traditionally modified an existing fighter. The F2H-2P and F9F-8P were followed by the F8U-1P.

The design modifications were developed while the F8U-1 fighter was in flight test. The major change was the reconfiguration of the forward fuselage for the installation of a set of cameras in lieu of the cannon and rocket armament. (The horizontal tail was reportedly reduced in size according to some but I can't find any evidence of that.) The prototype was a modification of the 32nd production F8U-1, BuNo 141363. John Glenn used the early production F8U-1P shown here to set a transcontinental speed record in July 1957.

In addition, Vought improved the area ruling of the airplane. There had been considerable concern before the first flight of the prototype F8U fighter when wind tunnel testing showed transonic drag to be higher than had been predicted. Vought hadn't paid much attention to the newly discovered area-rule concept up until then and hastily developed a set of modifications to refine the fuselage shape in accordance with it. One or two were actually incorporated prior to first flight, as a result of which it was discovered that the wind tunnel data was not correct and the F8U's long, slim fuselage was close enough to an ideal overall cross-section increase and decrease.

However, with area ruling in mind, Vought tweaked the F8U-1P fuselage cross section, bulging it both upward and outward between the cockpit and the wing, in part to provide a flat bottom to the fuselage (also see the profiles in the picture at the beginning of the post).

A Tom Weinel created comparison: 

The upper forward fuselage faired into a larger overwing fairing. (Also see the top picture.)

The inflight refueling probe, which had been added to the fighter in a large blister aft of the cockpit as an afterthought, was now fully enclosed within the fuselage. A window was added to the underside of the nose cone for a viewfinder so the pilot could accurately position the airplane for photography. The pilot could switch between two lenses, one with a narrow angle for use with the forward-facing camera (station 1) and the other, a wide angle for use with the cameras at stations 2, 3, and 4 which took pictures downward and side ward.

The instrument panel was dominated by the viewfinder.

Like the F8U fighter originally, the first F8U-1Ps had Vought-furnished ejection seats. These were replaced by the Martin-Baker seat, probably during the very late 1950s or very early 1960s. See http://thanlont.blogspot.com/2011/02/transition-to-martin-baker-ejection.html

The F8U-1P's fuel capacity was increased by 224 gallons over that of the F8U-1 fighter by extending the main fuel cell downward into the volume provided by the elimination of the rocket pack and adding a small fuel cell forward of the main fuel cell. This provided a significant improvement in mission radius and endurance.

The F8U-1Ps were redesignated as RF-8As in September 1962. Seventy-three of the original 144 were rebuilt between 1965 and 1970 to add an uprated J57 and ventral fins; these were designated RF-8G and retained their original BuNos. (Five Marine Corps RF-8As reportedly got ventral fins early; high-speed directional stability was marginal without them.) At least some got the later wing with hardpoints for external stores and wiring changes for an ECM pod.

A subsequent upgrade in 1977 resulted in a change to the more powerful J57-P-420, which required the addition of the external cooling intakes on the upper aft fuselage; there was, however, no change in the designation.

Various ECM antennas were added to the vertical fin over time, including a large forward-facing one.

The bleed air exhaust on the right side of the fuselage just ahead of and below the wing leading edge had a less prominent fairing than the fighter's.

The last iteration of the RF-8G also was converted to later single-duct configuration as depicted in this Tom Weinel illustration:

For a walk-around photos by Chris Ishmael of an RF-8G with the external AB-cooling intakes in a museum, see http://www.cybermodeler.com/aircraft/f-8/rf-8g_walk.shtml

For some illustrations from the flight manual, courtesy of the Marine Corps Aviation Reconnaissance Association, see http://www.mcara.us/F8U-1P_RF-8A_design.php

There are were no complete kits of the F8U-1P/RF-8 until late 2023, when Sword released an excellent 1/72 one. See http://tailspintopics.blogspot.com/2023/12/sword-172-f8u-1prf-8-photo-crusader.html.

Also in 1/72 scale, there are vacuform conversions from Falcon and Airmodel and resin conversions from Ventura (see https://hangar47.com/rf-8a-crusader/) and RVHP; only the RVHP kit includes decals and its accuracy is questionable. There is a review of the 1/72 Final Touch conversion parts and Tasman decals here: http://modelingmadness.com/review/viet/mansrf8.htm. As far as I know, only the Falcon version is readily available. See  http://www.falconmodels.co.nz/kits.html

In 1/48, see Tom Weinel's post in Hyperscale HERE.

Last, but definitely not least, Fisher has released an excellent RF-8G conversion for the Trumpeter 1/32 kit. See http://fishermodels.indiemade.com/product/rf-8g-photo-crusader-conversion-132

AD (A-1) Skyraider Original vs Extraction Seat

The Navy contracted for the incorporation of the Stanley Aviation Corporation Yankee seat in at least two squadrons of its AD (A-1) single-seat Skyraiders. This was an extraction system as opposed to an ejection seat. In the event that the airplane needed to be jettisoned, the pilot was pulled out of his seat by a cable attached to a rocket as opposed to riding a seat that was propelled by a rocket (originally an explosive charge) out of the airplane. For more on the Stanley seat, see http://tailspintopics.blogspot.com/2011/10/yankee-tractor-rocket-escape-system.html.

The original AD seat and the one incorporating the extraction system were similar in appearance but very different in detail. The most obvious indication of the Stanley seat is the presence of a tube (the rocket) added to the right side of the existing canopy actuation mechanism that was usually concealed under a canvas cover (I'm not sure why but I suspected that it was prone to leaking).

The armor plate behind the pilot's headrest appears to have been unchanged but the head rest was now mounted to the seat structure, which included two U-shaped channels on each side of the seat.

An extraction initiation handle was located at the front side of the seat cushion.

The headrest of the original seat was narrower, with its forward surface bowed outward vertically, and mounted to the armor plate. The seat consisted of a back and a bucket. (Note that the canopy actuation mechanism is not shown in the following illustration and that there would almost always be cushions/parachute in the seat.)

There was, of course, no extraction handle.

This is the comparable illustration for the Yankee seat. (Note that the control column is not shown.)

The Air Force modified both its single-seat and wide-body Skyraiders with the extraction system.

Lockheed P/F-80 Canopy Development

Why do I make a blog post concerning an Air Force fighter? Because the Lockheed P/F-80 was operated by the Navy, including an at-sea evaluation of the P-80A. The Navy also operated some F-80Cs as jet trainers. One subtle difference between the two models (and it must be pretty subtle because it seems to have been recognized only rarely and not by kit manufacturers) is the location of the windscreen and the length of the canopy.

I've covered the carrier-trials P-80A here: http://tailspintopics.blogspot.com/2011/11/lockheed-p-80a-carrier-trials.html ; much of the same material was covered in a Tailhook Topics Draft post here: http://tailhooktopics.blogspot.com/2012/02/lockheed-p-80-shooting-star.html.

Craig Kaston just provided me with photos that he took this weekend of the P-80A at the Planes of Fame Museum in Chino and the P-80C fuselage in the storage yard at the Yanks Air Museum. They provide a direct comparison of the location of the windscreens of the two canopies with respect to panel lines and access doors whose location did not change, e.g. the aft cockpit bulkhead and the instrument panel, when the canopy was redesigned for the installation of the ejection seat.

Note that the Planes of Fame P-80A has the later F-80C canopy resting on the top of the fuselage* (it probably wouldn't fit properly if it was closed because of the different mechanism used to slide it). The extra length of the F-80B/C sliding canopy (the location of the aft end of the canopy remained the same on both the A and the B/C, so the length increase required by the relocation of the windscreen was in the forward part of the sliding canopy) is also evident by the fact that the aft interior structure of this canopy would not rest against the cockpit headrest when the canopy was closed.

Craig also pointed out the difference in the boundary layer vent that I had not noticed.

*It is an example of the occasionally necessary and inobvious kludge by museums that sometimes leads to a blunder by model kit manufacturers.

Things Under Wings - Drop Tanks Update

For a primer on Douglas drop tanks, see http://tailspintopics.blogspot.com/2011/07/douglas-low-drag-external-fuel-tanks.html

Now take a close look at this picture:

Normally, both the A4D and the AD would have 300-gallon drop tanks under the wings. In this case, however, the A4D is carrying 150-gallon tanks and the AD, which is in the standard tanker configuration, 400-gallon tanks.

For more on the AD tanker configuration, see http://thanlont.blogspot.com/2013/10/texaco.html

A3D Skywarrior External Pylons

Rick Morgan provided the following with respect to the A3D-2T Skywarrior external pylons discussed here: http://tailspintopics.blogspot.com/2013/09/ta-3b-skywarrior.html. (Rick also provided pictures of TA-3Bs with the pylon and practice bomb dispenser that I've added to that post.)

Concerning pylons on A3Ds, as I understand it all of the Versions had hardpoints to attach them.  This is a photo of a VQ-2 EA-3B in the Med refueling from a VA-216 A-4B off Saratoga in 1967 with what I believe is an ALQ-31 pod installed.

An old VQ friend tells me that they actually flew fighter training missions during this period with the equipment due to the lack of other EW assets in 6^th fleet, most of the other aircraft being in Vietnam.  This is the only time I’ve found so far where EA-3Bs were actually used for active jamming. (Contrary to a lot of published references, I have yet to find a VQ operator who used the EA-3B for jamming in Vietnam- the stories undoubtedly confuse the EAs for EKAs).

The ERA-3Bs  at VAQ-33/34 carried ALQ-76 pods on their pylons, of course.

For a brief description and a picture of the ERA-3B (and an explanation of A-3 Bombers versus Versions), see http://tailspintopics.blogspot.com/2010/09/mighty-skywarrior.html