AD-4 Skyraider Variant - AD-4B

Because of its range, the AD Skyraider would be one of the U.S. Navy's carrier-based airplanes assigned to missions employing nuclear weapons. One of the relatively lightweight ones was the Mk 8. Like Little Boy. which was dropped on Hiroshima, it utilized a gun-type method of creating a supercritical mass by literally firing one non-critical mass, a cylinder, down a steel tube onto another non-critical mass, a post. When the cylinder reached the post, the combined mass was supercritical and exploded.

While relatively inefficient compared to an implosion device like Fat Man, not to mention very heavy (because of the big "gun" barrel) compared to the yield, it was also much less likely to malfunction when used to destroy an underground target like a submarine pen. The Mk 8 could reportedly penetrate 22 feet of reinforced concrete before detonating.

 

 

The center pylon and belly of the AD-4 had to be modified for the Mk 8 because its weight, about 3,250 lbs, far exceeded its 2,000 lb design capacity, and its suspension lugs were 30 inches apart compared to the 14 inch distance between the latches on the existing Skyraider center-line bomb rack. Since the two forward spars of the wing weren't far enough apart for the longer rack required, instead of being embedded in the bottom of the fuselage it was located below the AD-4B's belly and housed in a streamlined fairing. In addition to beefing up the structure to which the bomb rack was attached, the modification also included the creation of a recess in the belly to provide clearance for the Mk 8 tail fin.

 The following picture is actually the bottom of an early AD-6 but the recess was carried over, at least for a while.

The recess could be closed off by a panel when a Mk 8 was not being carried.

The AD-4B could also carry the Mk 7 nuclear weapon, which was much bigger than the Mk 8 but only half as heavy.

The external center-line pylon was retained for the AD-5 and -6/7.

Thanks to Ed Barthelmes for his help with documentation needed for this post.
 

Douglas AD-4 Skyraider Variants

 This is a work in progress...

 The AD-4 prototype, BuNo 122853, on 27 September 1949.

I've done a few posts on the AD-4W, the Airborne Early Warning Skyraider:

 https://tailspintopics.blogspot.com/2018/06/ad-4w-skyraider.html

 https://tailspintopics.blogspot.com/2019/11/douglas-ad-4waew1-and-sword-172-scale.html

https://tailspintopics.blogspot.com/2019/08/sword-172-douglas-ad-4w-skyraider.html

https://tailspintopics.blogspot.com/2021/12/sword-172-ad-4w-redux.html

https://tailhooktopics.blogspot.com/2019/11/douglas-ad-4waew1-antenna-configurations.html

I've also recommended three softcover monographs on the Skyraider with material of interest to the scale modeler: https://tailspintopics.blogspot.com/2011/10/ad-skyraider-modeling-notes.html

This is a summary of AD-4 variants (other than the AD-4W and one or two others that were not produced in quantity) and associated Bureau Numbers:

AD-4: Single-seat conventional attack

AD-4B:  Single-seat special stores (nuclear) attack: added external center pylon and Mk 8 tail fin recess

AD-4L: Winterized with deice boots on wing and empennage leading edge and propeller and windshield anti-icing

AD-4N: Three-place (no dive brakes) all-weather attack, ECM, and ASW

AD-4NA: All-weather mission equipment removed

AD-4NL: AD-4N with winterization

AD-4Q: Two-place radar location and jamming and provisions for target tow

Bureau Numbers

122853 AD-3 (AD-4 prototype)

123771 - 124006 AD-4 (123935 and 123952–124005 to AD-4L; 124006 to AD-5)

124037 - 124075 AD-4Q

124128 - 124156 AD-4N (124760 to AD-4NL)

124725 – 124760 AD-4N (All to AD-4NL)

125707 – 125741 AD-4N

125742 – 125764 AD-4NA

126876 – 127018 AD-4N (Most to AD-4NA)

127844 – 127853 AD-4 (127845-52 AD-4L)

127854 - 127872 AD-4 (127854-60, 127866, 127868-72 to AD-4B)

127873 – 127879 AD-4

127880 – 127920 AD-4N  (Most to AD-4NA)

128917 – 129016 AD-4 (128937-43 and 71-78 to AD-4B)

132227 – 132391 AD-4B

Skyraider kits other than AD-5 and AD-4W almost all represent the AD-6. The most notable difference between the late AD-4 and the AD-6—other than antennas and similar small details—were the stores pylons. This post illustrates the pylon differences: https://tailhooktopics.blogspot.com/2015/07/douglas-ad-1-skyraider-pylons.html

Another example of the flush AD-4 center-line store rack is provided here: https://tailspintopics.blogspot.com/2018/04/things-under-wings-va-195-kitchen-sink.html

The AD-4 configuration also changed during its production run. Most of the improvements were retrofitted to delivered airplanes as well. The two most significant were the addition of another 20 mm cannon in each outer wing panel just outboard of the fold joint and "armor". For the latter, see https://tailspintopics.blogspot.com/2013/07/ad-armor-all.html. Others included the exhaust glare shield addition, static-pressure source location, antenna changes, and wing-tip navigation light location. Nose flaps on the inside of the cowling were added effective with BuNo 123880; for a description of the nose flaps and their operation, see https://tailspintopics.blogspot.com/2011/10/ad-skyraider-modeling-notes.html

The AD-4 also predated the development of the Douglas high-speed fuel tanks. Some examples of these post-WW II fuel tanks are illustrated here: https://tailspintopics.blogspot.com/2016/09/things-under-wings-post-war-external.html

Even the single-seat AD-4 had provisions for radar. Some of the different types of radar pods that it and the multi-seat AD-4 attack variants could carry are illustrated here: https://tailspintopics.blogspot.com/2012/11/things-under-wings-radar.html

 More to follow...