Originally posted in “Argentine militaria” moved here for being Malvinas related.
The Torpedo Armed Pucará
The South Atlantic conflict caused the Argentinean Armed Forces to face not only a world power when it comes to military might, but also their own internal limitations and failures in warfare.
Not only the maritime might, but the certain threat posed by the British submarines was evidenced with the sinking of the cruiser ARA “General Belgrano” on 02-May-82, and for this reason, the Argentinean Navy and Air Force sought to implement solutions to counteract this troublesome situation.
Despite the controversial decision to withdraw the ships from the fleet to safer waters, the Naval Aviation developed, besides their attack operations to naval targets, many options to protect the fleet from attack coming from enemy ships and submarines, and part of the success of these options was due to the withdrawal of the fleet to shallow waters.
On the other hand, the Air Force, despite having had little experience in attack operations against naval formations, began to evaluate the possibility of adapting aircraft and to develop tactics specifically aimed to
that end, in an attempt to increase its attack capabilities.
By the middle of May, 1982 the Strategic Air Comand of the Air Force decided to undertake a series of test flights, with the purpose of make operational the IA-58 Pucará, armed with torpedoes.
The weapon chosen in this case, would be the U.S. built Mk.13 torpedo, which by then had almost been withdrawn from use by the Argentinean Navy. Built between the years 1944 - 1952, it was a sturdy weapon, having been designed to be launched from boats and aircraft.
While not being the most modern weapon, the large number of examples remaining in the inventory caused its selection for the evaluation being conducted. The then Comodoro Jorge S. Raimondi was placed in charge of the project, conducted at the Naval Base of Puerto Belgrano, in order to obtain cooperation from the Navy. The Navy quickly supplied enough torpedoes, which were equipped then with the brackets necessary to mount them to the airplanes, and after a long time of inactivity, the torpedoes’ mechanisms and systems were back in service.
On 21 May, lands at the Comandante Espora air base, Pucará registered as AX-04, which had been assigned to the Centro de Ensayos en Vuelo (Flight Testing Center) at the Area Material Córdoba, flown by Capitán Rogelio R. Marzialetti and the Supervisor Mario A. Loiacono (both belonging to the CEV).
This specific aircraft was a standard series unit (A-509) having been modified after leaving the assembly line, to be employed as prototype for the evaluation of weapons and aircraft systems, and having as part of its equipment, a film camera to be employed to document the moment when the torpedo was launched. The torpedo was carried on the aircraft’s Aero 20A-1 central weapons station.
The first launch of a Mk.13, takes place on 22 May, the torpedo having been a practice round, not equipped an explosive head. The launch zone established by the Navy, was located 40 miles from Puerto Belgrano, and would be the same location where later the same day, the second test launch would take place.
Launch involved having the aircraft establish a 20 degree dive, at a speed of 300 knots and at approximately at a height of 100 mts., resulting on the destruction of the torpedo when it impacted the sea. The same happens the next day when the parameters were a 45deg. dive, speed of 250 knots, and approximate height of 200 mts.
It became evident that there was something missing for the torpedo to be effectively deployed from an airplane with the performance of the Pucará.
Lacking the torpedo’s operational manuals for air deployment, the only information available was that it 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.
After consultations conducted with retired sub-officers who had been assigned to the Army’s torpedo shops, a nose-mounted aero-dynamic brake was installed on the Mk.13, and a biplane stabilizer was installed in the tail end, additions that would be destroyed when the torpedo hit the water.
After these modifications were undertaken, the first successful launches take place on 24 May, off Trelew, in the waters of the San Jose Gulf. These took place while the airplane was on a straight and level flight attitude and at a height of 15 meters, and it was then determined that the optimal speed was 200 knots, since higher speeds caused the torpedo to impact the bottom of the sea.
A total of 7 practice runs were conducted, and another 10 launch, this time with an explosive head, was conducted on 10 June, on a zone with deeper waters and near cliffs, North of the Port of Santa Cruz, but the depth here was not enough to compensate for the speed of 250 knots developed by Pucará A-566 which hade replaced AX-04 on the testing.
A last attempt is conducted on 14 June, in the neighborhood of Pingüino Island (near Puerto Deseado) chosen because of its maximum depth and ruggedness of the shoreline, and establishing a definite launch speed of 200 knots, but while the preparations for launching were taking place, this operation is completelly cancelled, due to the surrender of the Argentinean troops which were fighting in the Malvinas.
It is worth mentioning that at the same time that this project was being undertaken, studies were also conducted regarding the launching from the Pucará, of anti-ship mines Mk.12, in an attempt to mine the San Carlos Straits (in the Malvinas Islands), but this did not go beyond the loading up testing of the mines to the airplane.
While these testing operations were taking place, the Air Force deployed a section of IA-58A Pucara from the Grupo 3 de Ataque, to the airport of La Plata (Buenos Aires) to conduct patrolling missions on the approaches to the Río de La Plata, due to the possibility of British submarines operating in the area.
The end of the South Atlantic conflict, marked the end of the evaluation of the employment of the Pucará for the delivery of torpedoes and other specific weapons, for use against naval targets, and the aircraft involved in the testing, were returned to their parent units.
http://www.laahs.com/artman/publish/article_105.shtml
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