by Tommy H. Thomason

Saturday, December 24, 2022

Sikorsky RH-3A Sea King Minesweeper

 For a brief history of USN helicopter mine sweeping, click here:

The RH-3A was the first of the Navy's mine-sweeping helicopters to be used operationally. Nine were converted from early production HSS-2 Sea Kings, BuNos 147139-142, 147144, 147146, 148038, and 148040-041. Some sources claim that conversions included 147138, but according to Tom Chee, it was stricken on 1 October 1959 as a result of Sikorsky flight-test related incident on 9 September 1959. RH-3A conversions didn't begin until December 1965.

The major changes to the SH-3A were the removal of all the ASW equipment and the addition of a large sliding door on the left side, bulged observation windows at the rear of the cabin on each side*, and rear-view mirrors for the pilot and copilot; a beef up of the lower aft fuselage above the tail wheel; and the addition of the mine-sweeping hardware including a tow reel in the cabin. They reportedly received a larger diameter, beefed-up tail rotor at some point due to the loads on the tail rotor while sweeping.

A right side view:

A left-side view:

Mine sweeping gear was deployed out of the right side of the cabin after attachment to the boom.

The mechanism required to rotate the boom and tow cable from alongside the cabin into the streaming position was pretty complicated:

Some other pictures:

The forward fuselage of an HC-7 RH-3A:

 An explanation of the "kill" scorecard by the forward entrance steps:

Jodie Peeler noted that RH-3As were also operated from Ozark (MCS-2):

Like Catskill (MCS-1), Ozark was a former minelayer/landing ship that was converted into an
oddball "mine warfare command and support ship," typical of the odd ducks often seen in this era of the Navy. A friend's dad served on Ozark in 1969 in that era (has recollections of being prepared for duty as
Atlantic Fleet recovery ship if Apollo 10 had gone wrong) and that's how I first became aware of the RH-3A.

What look like lifeboats are small mine-sweeping launches (MSLs). 

After being replaced by the RH-53A, the surviving RH-3As were stripped of the mine-sweeping hardware (but retained the cabin doors on each side and the bulged aft cabin windows) and redesignated UH-3As:

via Jodie Peeler

* Note that the combat-rescue HH-3As also had aft cabin windows on both sides but these were located one frame forward of the RH-3A's. HH-3As also did not have the left-side cabin sliding door.

Friday, December 23, 2022

A Brief History of USN Helicopter Minesweeping

Many of the problems that the helicopter was the solution for were identified in the decade or so after Larry Bell and Igor Sikorsky were successful with theirs. One was mine sweeping. In October 1950, the U.S. Navy needed to sweep the waters off Wonsan, Korea for an amphibious assault. Due to budget restrictions and the lack of need following World War II, mine-sweeping capability/capacity had been neglected by the U. S. Navy while other countries had focused on anti-ship mine development. As a result, a very small force of mine sweepers was tasked with clearing what proved to be an enormous field of Soviet-supplied mines. Light observation helicopters were used to spot mines ahead of the sweepers but the pilots and observers could only detect ones floating near the surface, a small portion of the defense-in-depth of various mine types. Although eventually successful in clearing an approach into the harbor, three mine sweepers were sunk, two USN and one ROK, and more than a dozen sailors killed.

The problem was that the mine sweeper on point, leading a wedge of mine sweepers clearing a channel, was too susceptible to being sunk by a mine. What a helicopter could do was tow sweeping gear ahead of the lead ship to minimize the risk to it of a mine encounter without risk to itself.

VX-1 commenced helicopter-tow testing with the Piasecki HRP-1 tandem-rotor helicopter in November 1952. It was the biggest, most powerful helicopter available at the time. For the testing off Panama City, Florida, they were stripped of fabric to reduce download and weight. Flotation was also added to allow for a water landing in the event of failure of its single engine.

The Navy borrowed at least one Piasecki H-21 helicopter from the Air Force in 1953 to evaluate it as a candidate for operational mine sweeping. The tandem-rotor configuration was preferred because all of the engine power went to lift and unlike a single-rotor helicopter with a tail rotor, it was insensitive to cross and tail winds.

In 1954, the Bureau of Aeronautics contracted with Bell Helicopter to make modifications to its HSL antisubmarine warfare helicopter to optimize it for mine sweeping. One requirement was to insure adequate engine cooling and oil supply at extreme nose-down attitudes.

By 1956, the HSL was successfully qualified as a mine sweeper and adequate numbers had been built for a mine-sweeping fleet. Here it is pulling a large salvage barge to demonstrate its towing capability.

However, when further HSL production for the ASW mission was cancelled in favor of the Sikorsky HSS-1 Sea Bat, the HSL was not deployed and utilized only for development of mine-sweeping gear. (For more on the Bell HSL program, see my monograph:

In October 1962, the CNO directed BuAer to develop an operational helicopter minesweeper. The tandem-rotor Vertol H-46 was preferred but the decision was to convert nine early production SH-3As to the RH-3A configuration instead (the R prefix indicated a modification for reconnaissance, which apparently was considered to be the most descriptive of those available). Beginning in 1964, Sikorsky removed the ASW mission equipment from these helicopters and installed tow hardware on a beefed-up lower rear fuselage. A sliding door was added to the left side of the fuselage and a bulged observation window added on each side of the fuselage at the rear of the cabin.

In September 1966, NATC (Naval Air Test Center) accomplished a two-day shipboard suitability test of the RH-3A aboard Ozark (MCS-2). In 1967, HC-6 on the east coast and HC-7 on the west coast commenced operations with RH-3As.

Although demonstrating capability, there were teething-problems (the tail rotor proved inadequate and was reportedly replaced by a larger one, for example) and the RH-3A was under powered for some towing equipment. As a result, the Navy transferred 15 CH-53As from the USMC to AMCM (Airborne Mine Countermeasure) duty. These were equipped with more powerful engines and modified for the mine-sweeping mission. In addition to being larger and more capable, they had a rear ramp that made deployment, observation, and retrieval of the mine-sweeping gear much more straightforward. These were designated RH-53As and in 1971 assigned to a new helicopter squadron, HM-12, that was dedicated to mine sweeping.

In the meantime, BuAer had contracted with Sikorsky for 30 RH-53Ds, a derivative of the CH-53D Sea Stallion, which had first flown in January 1969. HM-12 received the first of these in August 1973. These were further refined for the mission, including the addition of inflight refueling capability.


Further development of the H-53 resulted in the CH-53E Super Stallion, a major upgrade that added a third T64 engine aft of the main transmission for even more power. The MH-53E Sea Dragon was the mine-sweeping variant, with the prefix "M" for multi-mission replacing the prior "R".  It featured huge sponsons for additional fuel capacity and a flight control system optimized for the mine-sweeping mission. The prototype first flew in December 1981. It was deployable in 1986, replacing the RH-53Ds. Fifty were built.

U.S. Navy photo by Chief Mass Communication Specialist Edward G. Martens

In the late 1990s, the CNO initiated a program for a set of AMCM systems to be utilized by deployed helicopter squadrons flying the MH-60S Knighthawk, which is otherwise utilized for cargo/personnel transport. It is not a mine sweeper per se, but can be equipped to spot some mine types and neutralize them. An MH-60S (HSC-28) and an MH-53E (HM-14) at NAS Key West during joint MCM exercises in 2021:

LT Rich Babauta

Friday, October 28, 2022

Hasegawa 1/72 CMV-22B Osprey

30 October: Added VRM-30 information

I am very pleased that Hasegawa elected to reissue their excellent 1/72 V-22 Osprey kit as the Navy's CMV-22B COD. For background on this aircraft and mission, see:

I had bought the J.G.S.D.F Transport Aviation Group kit because it had some of the same antenna details and was contemplating how to add the greatly enlarged forward end of the sponsons (a CMV-22 unique feature that added extra fuel). Now that problem is solved and as an added bonus, I don't have to come up with the necessary decals.

Scott Van Aken provided a inbox review of the kit for Modeling Madness:

One build note concerns the modification of the forward end of the sponson. Hasegawa provides a resin part that fits over the kit sponson to create the bulged one. It doesn't fit particularly well (nothing that trimming, filling, reshaping, sanding, etc. can't rectify) but beware, it doesn't fit particularly well three different ways, two of which are wrong. Worse, neither the sprue that they are on nor the parts themselves are marked to denote which side they go on. In Hasagawa's defense, the assembly illustrations do depict, if you examine them and the part closely, the correct orientation of the parts and which side they go on. However, the first time I dry fitted one, having just glanced at the instructions (Cavin: "Do I look like a sissy?"), I put it on incorrectly and was about to write that Hasegawa had got it wrong.

This is a bottom view of the sponsons:

This is the correct way to orient the part (note that the one in the picture taken from above is too far forward):

This is incorrect:

This is also incorrect:

Note that the upper surface of the addition at the same height as the original sponson; the bottom of it is flat (both laterally and longitudinally, see picture above) but lower than the belly (and the kit part may not go low enough).

The shape is very complex, particularly the forward outboard corner, which appears to be slanted outward from top to bottom:

There also appears to be an intersection where the forward end of the addition ends just before the forward end of the original sponson.

Note the straight line of the top of the sponson going forward, the symmetrical fore and aft bulge downward of the addition, and what appears to be a flat area at the forward outboard corner of the addition as noted above:

One oddity of the CMV-22B deployments so far is that none of the Ospreys have been marked with a unit tail code. That is, until now, assuming that "SB" has now been assigned to VRM-50.

And another, a crop of a photo by "manyinterests2020" on Reddit, tail code DC?

No unit marking on this aircraft, but the other CMV-22 COD unit is VRM-30 and the fin decoration is similar to its badge:

Many photos, pre fin color, here:

Wednesday, August 31, 2022

Obscureco 1/72 F7U-3/3M Detail Set

 Obscureco Aircraft ( has produced yet another detail set that will be of interest to U.S. Navy airplane modelers, OBS72030. It includes a full cockpit including an early and late ejection seat pan; the top of the fuselage behind the ejection seat including the canopy actuator; the nose gear wheel well; and a refueling probe. It replaces the equivalent "okay" parts provided in the otherwise excellent Fujimi F7U-3 kits with much more accurate and detailed resin ones.

The two-page instructions provide a detailed, step-by-step assembly guide and detailed color information.

Chris Bucholtz

Obscureco is in the process of updating their website so this kit may not yet be listed but it is available to order. The price is $20 plus the shipping cost provided here along with other purchasing information:

Wednesday, August 3, 2022

Roden 1/72 North American AJ-1 Savage

13 November 2022: Illustrations of the inflight refueling system are provided here:

 23 October 2022: Illustrations of the hardware required to fold the wings and vertical fin of the AJ are provided here:

22 October 2022: The kit out-of-the-box does not provide for open bomb bay doors. Many modelers would have no trouble separating the doors and assembling them in the open position. The configuration is illustrated here:

4 August 2022: I've added a post summarizing the configuration of the different AJ Savage canopies here (at this point, the kit has the No 1 canopy that was on a few early AJ-1s):

3 August 2022: Totally unexpected:

I got a preview of the instructions and pictures of some of the tooling a month ago. It looks very good: lots of interior detail (and a Mk 4 bomb, around which the Savage was designed). One nit of confusion with the -2 configuration, easily remedied, is the nose landing gear door configuration (I had previously alluded to another one but incorrectly, as it turned out). While you're waiting, here is some reference material to peruse:

More later...

Sunday, April 24, 2022

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.

Wednesday, April 20, 2022

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:

I've also recommended three softcover monographs on the Skyraider with material of interest to the scale modeler:

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:

Another example of the flush AD-4 center-line store rack is provided here:

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 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

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:

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:

 More to follow...

Sunday, February 27, 2022

SUNDOWNER Phantoms by Angelo Romano with Michael Grove

The full title says it all:

It's a good synopsis of 68 pages of text and high-resolution color photos on heavyweight gloss paper.

It also includes a brief history of VF-111 going back to October 1942 when its predecessor, VF-11, was established and the origination of its name and insignia that alluded to its purpose, helping win WW II in the Pacific.

The remainder of the large, landscape-format paperback is devoted to a fairly well detailed, extremely well illustrated history of the squadron's operational history flying the F-4 Phantom. It includes a listing of Bureau Numbers assigned (and summary history), their tail codes and side numbers, large color photos of almost every one at some point in its assignment to the squadron, notable configuration changes, and marking changes over time with closeup pictures of significant ones.

It concludes with a multi-view (top and bottom, left and right side) color illustration of the paint and makings of F-4B BuNo 153019 after its crew had shot down a NVAF MiG-17 on 6 March 1972, including color and marking specifications.

Although billed as a modellers' guide, the text includes a summary history of both the squadron's operations and world events when it was assigned Phantoms.

One picture of a Sundowner F-14 is included along with the promise, "The history of the SUNDOWNERS and the F-14 , from 1978 through 1995, will be the subject of a future book in this series".

For more detail on the configuration differences among the F-4s, see

I urge you to buy this monograph directly from Fly Shop if you can, which benefits Angelo more financially, enabling him to continue to research and produce his excellent books on U.S. naval aviation.