AX-04: Last Torpedo Bomber development of the 20th Century?

Grey Havoc

ACCESS: USAP
Senior Member
Joined
Oct 9, 2009
Messages
16,994
Reaction score
6,624
Could the IA-58 Pucará be classified as the last Torpedo Bomber, at least developmental wise, of the 20th Century?

For those of you who are not familiar with it, AX-04 was a prototype of the IA 58 Pucará, modified during the Falklands War as part of a joint Air Force/Navy project hoping to improve the anti-ship capabilities of operational Pucarás by equipping them with Mark 13 Torpedoes drawn from Naval stocks. The Mark 13, which before the war was in the process of being retired from Argentinean service, had been used primarily by PBY-5A Catalinas, prior to their retirement in 1958, but at the time of the Falklands War, the Armada (Navy) still had a large inventory of Mark 13s, so in May 1982, the FAA (Air Force) decided to try and make use of that fact, with the full co-operation of the Navy, in particular it's Aviation Branch.

Project work began sometime prior to May 21st, 1982. On that date, AX-04 arrived at the FAA's Comandante Espora airbase. AX-04 was originally a series production airframe (A-509), which had being modified into a weapons and systems testbed, post assembly line (pre-war). Prior to the torpedo project, AX-04 had been assigned to the Flight Testing Center at the Area Material Córdoba. The ferry flight was undertaken by two members of the Flight Center, a Capitán Rogelio R. Marzialetti and a (civilian?) Supervisor Mario A. Loiacono. The project though, was actually headquartered (and a lot of the actual work was carried out) at the Navy's Puerto Belgrano base.

Among the initial modifications made to AX-04 for it's role in the project was a film camera to record the torpedo drops. The test torpedoes were carried on it's centerline weapons station.

There were a number of obstacles standing in the way of the project team however. Among them was the fact that it had been so long since the Navy had used airdropped Mark 13s, that both institutional experience with and documentation relating to the use of, the Mark 13 had being lost. This unfortunately included the operational manuals for air deployment. Another problem was both the torpedoes, and the equipment required to operate them from aircraft (e.g. mounting brackets), had been in storage for a long time, especially in the case of the latter, although apparently this didn't prove as much of a problem as feared, reactivation going relatively smoothly for the most part.

The lost documentation and lack of practical experience with the use of the Mark 13 from aircraft proved to be a much bigger problem, as was soon proven by the first test flights.

The first test drop, using a practice round with a inert warhead, took place on the 22nd of May. The Navy had established a test area just off Puerto Madryn, in the Golfo Nuevo, 40 miles from Puerto Belgrano.* The second test took place at the same location later the same day, with the third test drop the day after. All three initial tests were unsuccessful.

The conditions for the first two tests were as follows: Launch involved having the aircraft establish a 20 degree dive, at a speed of 300 knots and at approximately at a height of 100 metres. This, however resulted in the destruction of the torpedo when it impacted the sea surface. The same result occurred the next day when the parameters were changed to a 45deg. dive, speed of 250 knots, and approximate height of 200 metres.

Due to the lack of documentation, all that was known for sure about the conditions for successfully airdropping Mark 13s was that the torpedo should enter the water at an angle of approximately 20 degrees. With a less acute angle, the torpedo would bounce when hitting the water, thus damaging the internal and propulsion mechanisms, and if the angle was greater, then there existed the risk that it would "spike" itself on the bottom of the sea.

Given the urgency of the requirement the project was trying to meet, a solution had to be found, and quickly. With the help of retired sub drivers who had been working at the Navy's torpedo workshops, modifications were made to a number of Mark 13s. These consisted of the installation of a nose-mounted aero-dynamic brake, and of a biplane stabilizer which was installed in the tail end. These additions were designed to break cleanly away from the torpedo body when the torpedo hit the water.

With these modifications in hand, the next round of tests took place on May 24th, and were highly successful. These tests, 7 drops in all, took place while the airplane was on a straight and level flight attitude and at a height of 15 meters. From those tests it was determined that the optimal speed for torpedo drops was 200 knots, since higher speeds caused the torpedo to impact the seabed.

The next round of tests, this one consisting of ten drops with live warshots, took place on June 10th, 1983, at a new location in deeper waters off cliffs North of the Port of Santa Cruz. However this was not as successful as the May 24th tests. By now another Pucará, A566, which was apparently borrowed from a operational unit, had taken over test duties from AX-04, with the latter being assigned to another important project (see below). The problem with the new round of tests was not the change in aircraft, but a seemingly revised requirement to carry out the drops at a speed of 250 knots rather than the 200 knots that proven to be the optimal drop speed. This appears to have been an attempt to improve the survivability of IA-58s in actual torpedo bombing operations, but it backfired. Despite the greater sea depth of the new test area, a number of torpedoes hit the seabed.

Further tests were scheduled for June 14th, in the neighborhood of Pingüino Island (near Puerto Deseado). This location was chosen apparently because it's shoreline and offlying seabed approximated operational conditions around the Falklands (or Malvinas as the Argentineans still refer to them as). While preparations for this new round of tests was taking place though, the entire project was made moot by the final surrender of Argentine forces in the Falklands and the end of the war. The project was terminated and all aircraft and personnel involved were sent back to to their parent units. This included a section of IA-58A Pucara from the Grupo 3 de Ataque of the FAA, who were operating out of the airport of La Plata (Buenos Aires) as part of project security. These particular Pucarás basically acted as ASW spotters, conducting patrols over the approaches to the Río de La Plata, due to the possibility of British submarines operating in the area.

Another project which was running concurrently with the torpedo project was a study into the practicality of deploying Mk.12 anti-shipping mines from Pucarás, in order to mine the San Carlos Straits (Falkland Sound). This project only got to the stage of test fits, at least some of which were carried out on the AX-04, which had just finished it's testbed role in the torpedo project.

*Have to double check this test location!

EDIT: One source has the torpedo project originating out of the FAA's Strategic Air Command while another source has it coming from it's Tactical Air Command? Can anyone who's familar with the Falklands era FAA clarify things a bit?

EDIT2: It looks like the project, or at least the concept for it, first originated around late April, 1982, at the short lived Commando Aereo de Estrategico (Strategic Air Command). See fourth post of this thread for more details.



http://www.ww2incolor.com/forum/sho...s-war-pictorial.-Post-yours-%A1%A1%A1./page19 (Scroll down to #282)
 

Attachments

  • pucara-t.jpg
    pucara-t.jpg
    7.3 KB · Views: 447
  • Puca4.jpg
    Puca4.jpg
    24.8 KB · Views: 149
  • pasadatorpedo.jpg
    pasadatorpedo.jpg
    18.6 KB · Views: 137
  • pucatorpedero2.jpg
    pucatorpedero2.jpg
    38.9 KB · Views: 141
  • pucatorpedero1.jpg
    pucatorpedero1.jpg
    63.6 KB · Views: 187

Grey Havoc

ACCESS: USAP
Senior Member
Joined
Oct 9, 2009
Messages
16,994
Reaction score
6,624
True. I'd known the Q-5 was (and still is) in service, but I hadn't realised that development work regarding it's torpedo bomber role had apparently continued into the '80s and early '90's.

On another note, a post at the below link claims that another goal of the IA-58 Torpedo Bomber project was to provide aircraft for use as the 'Killer' part of auxiliary ASW Hunter-Killer patrols around the Falklands, with the 'Hunter' component being the Navy's S-2E Trackers operating out of mainland bases. The post does not say what torpedo was supposedly intended for this role (the same poster did give details of the actual tests with Mark 13 torpedoes in an earlier post, as can be seen in the first link in the first post of this topic). The Armada did have stocks of Mark 34's and probably Mark 43's at one time, although they probably would have been of little use against British subs by the early '80's. They also may have had a limited inventory of Mark 44's.

I'm doubtful myself about this claim but I thought I would include it for the sake of completeness.

(Post #163)

EDIT: For those wanting a bit more info on the Mark 13:
 

TomS

ACCESS: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
4,972
Reaction score
2,550
Grey Havoc said:
EDIT: One source has the torpedo project originating out of the FAA's Strategic Air Command while another source has it coming from it's Tactical Air Command? Can anyone who's familar with the Falklands era FAA clarify things a bit?

First of all, thanks for researching this tpic. I'm very curious about the Falklands War, and info about Argentine topics remains frustratingly hard to find.

As to the topic of Strategic versus Tacitcal Air Command, I might be able to help a bit (or maybe muddy the waters further). It appears that the Strategic Air Command (Commando Aereo de Estrategico or CdoAeEstr) was a new organization created in early April 1982. It was supposed to monitor the British response to the invasion, track the Task Force, and create the FAA battle plan in reaction to that. For the surveillance role, it was given operational control over the FAA's long-range reconnaissance assets, such as the 707s. It was disestablished on 30 April 1982 and its assets turned over to the Southern Air Force Command (Commando del la Furza Aerea Sur or CdoFAS), which controlled all FAA assets in the Falklands area of operations. Given that, it seems unlikely that CdoAeEstr had much to do with the AX-04 torpedo experiments, though it's possible the project originated as part of its battle plan development.

I've not seen any sign of any organization called Tactical Air Command within the FAA, so I have no idea where that comes from. It sounds like an inappropriate mirror-imaging of USAF practice.
 

Grey Havoc

ACCESS: USAP
Senior Member
Joined
Oct 9, 2009
Messages
16,994
Reaction score
6,624
Thanks very much TomS! I've updated the initial post of this topic accordingly.
 

Pioneer

Seek out and close with the enemy
Senior Member
Joined
May 22, 2006
Messages
2,152
Reaction score
684
First of all, thanks for researching this tpic.

Yes, I second TomS sentiment Grey Havoc, and I'm sorry that I've only just stumbled across it.

Also thank you to windingroad on reminding me of the Q-5II's torpedo mission capability, which I have to admit, I'd completely forgotten.

Regards
Pioneer
 

DWG

ACCESS: Top Secret
Joined
Feb 11, 2007
Messages
1,504
Reaction score
1,716
Given the urgency of the requirement the project was trying to meet, a solution had to be found, and quickly. With the help of retired sub drivers who had been working at the Navy's torpedo workshops, modifications were made to a number of Mark 13s. These consisted of the installation of a nose-mounted aero-dynamic brake, and of a biplane stabilizer which was installed in the tail end. These additions were designed to break cleanly away from the torpedo body when the torpedo hit the water.

I meant to comment on this when it first appeared, but forgot. The mods sound like a recreation of the original Mk 13 airdrop attachments from WWII, the "pickle-barrel" on the nose and an air tail aft.
 

Roland55

ACCESS: Confidential
Joined
May 19, 2020
Messages
143
Reaction score
405
AttackRunBis.jpg
The instant where AX-04 dropped its Mk.13 torpedo in tests, its claimed that some of this tests were done in presence of a Type 42 to get a detection range and an overall estimation of drop range+direction.

This is the missing pic after the torpedo enters the water (see one of my previous posts)
ddkfrve-cf1a561e-e68b-4f59-9f8b-dbb0779d1efe.jpg

Although not a really good offensive weapon on itself (+ the fact that brought the aircraft to a really vulnerable position), it could have been best exploited as a weapon for already damaged ships, in other words, giving the "coup de grâce" to an already mortally/greatly damaged ship (the Case of HMS Ardent could have been further Exploited+ the ship that was providing help to put her fires out).
 

Similar threads

Top