Isaac Peral

Isaac Peral (Cartagena, June 1, 1851 – May 22, 1895, Berlin), was a Spanish scientist, sailor and inventor of the Peral Submarine (built 1884, launched 1888). Intended for military use, this submarine pioneered new designs in the hull, control systems and air systems, proving a success in two years of trials. Its ability to fire torpedoes under water while maintaining full propulsive power and control has led some to call it the first U-boat.

There are several streets in Spain named after Peral, including one at Moncloa/Universitario section of Madrid, and others in Málaga, Córdoba, Santander, Rota and Getafe.

The Peral submarine

The Peral submarine was first conceived on 20 September 1884, when Lieutenant Isaac Peral wrote in a paper several notes which would become his "Proyecto de Torpedero Submarino" ("Project for a submarine torpedoboat").

After several studies and experiments, and having gained support from his superiors and fellow officers, he exposed his idea to the Spanish navy, writing the following year (September, 1885) to the Spanish naval minister, vice-admiral Pezuela y Lobo, who ordered Peral to immediately go to Madrid and have a personal interview with him. After this interview Pezuela y Lobo agreed to finance Peral's preliminary studies in Cádiz with an initial budget of 5,000 pesetas, before launching a program to build a full-scale submarine boat.

The first test consisted of testing human breath in a closed enclosure for several hours. For this, a room of 58 square meters was used, with an air storage cell, loaded to 79 atmospheres and a storage capacity of half cubic meter. In addition to instruments to measure the temperature and the humidity, there was a tube to expel viciated air from inside, through a 4 m/m waterproof cloak and three water buckets to maintain the humidity. Six people locked themselves inside the room; one of them had to leave an hour and quarter later, but the rest remained for a total of five hours, and the test was considered a total success.

On 21 July 1886, the new Navy Minister, rear-admiral Beranger, decided that the project be reviewed by the Centro Técnico de la Armada (Naval Technical Center in English), under the responsibility of Admiral Antequera. He considered necessary a more complete study of the actuator before undertaking the construction of the hull and the electric motor apparatus, authorizing Peral to carry out all the modifications that he thought worthwhile, granting him 25,000 pesetas.

On 5 March 1887, Peral communicated that the electric motor or "Apparatus of depth", as he called it, was ready. On 17th of the same month the Commander in Chief of Cadiz, Florencio Montojo, who headed the technical committee which oversaw the machine, gave the approval,asking Peral a budget for the submarine.

On 25 April, 1887 the submarine construction was finally approved by the government; Keel was laid down on La Carraca on 7th October 1887, although work didn't start until two weeks later. Nevertheless, the submarine had already undergone numerous modifications: Peral's original project of 1885 conceived of a 61-ton submarine, 18.8 meters long, with a beam of 2,52 meters and a single convert|40|shp|abbr=on electric motor for a single shaft. The submarine being built had a length of more than 22 meters, a beam of 2.87 meters, a beam of 2.76 meters, two convert|30|shp|abbr=on electric motors geared to twin screw, and a displacement of 77 tons surfaced and 85 submerged.

As for the motor-cooling system, this consisted of forcing compressed air stored in the submarine over the motors, and though the original project had needed 430 accumulators, the final project installed 613 with a weight of 50 kilograms: the total weight of the batteries was hence around 30 tons.

The top speed varied with the charge of the batteries. With a 1/4 tension the submarine was able to reach 4.7 knots, with 1/2 6.9 knots, with 3/4 8.9 knots, and with the batteries completely charged the submarine was able to reach 10.9 knots. The range of the boat again depended on battery charge level; Peral considered his original submarine able to reach 132 nautical miles at a speed of 6 knots.

The submarine was single-hulled, and the ballast tanks were located atn the inferior part of the hull, underneath the torpedo tube. This single torpedo tube was the only weapon in the submarine, with two hermetic covers on each end so the submarine could launch a torpedo submerged: firstly flooding torpedo tube, firing the torpedo, unflooding the torpedo tube, reloading and repeating the operation. Mechanisms used for reloading were simple and fast, and the submarine had three reserves. In order to avoid expenses the torpedoes that the Peral embarked on trials were loaned, two from the torpedoboat "Retamosa" and one from the "Barcelo".

The air regeneration in the interior of the submarine was obtained by moving the air using an auxiliary motor of 6 hp (that also served for the bailing pump), after passing it through a Sodium Hydroxide purifier, eliminating CO2 exhaled by the crew. In addition the same pump served to inject oxygen when needed.

Immersion of the submarine was obtained by means of the "Aparattus of depth" which drove two shafts of vertical axes, located at both ends of the hull, moved by two electrical motors of convert|4|hp|abbr=on in charge to submerge or emerge the submarine and to maintain the horizontal stability in immersion. Ballast tanks as described above had a storage capacity of 8 tonnes, and were used to stabilize the submarine. In order to navigate, Peral used a magnetic needle installed in the ceiling of the turret, made of bronze. This avoided any electrical influences over it. He also devised a quasi-periscope, that was a fixed tube on the turret and by using a series of prisms, projected the outside world to within the submarine.

The Peral was launched on 8th September 1888, sixteen days before another pioneer electric submarine, the french Gymnote. On 6th March 1889 her sea trials started, which consisted of handling and surface navigation. On 7th August that year, she submerged for the first time up to the turret. Eighteen days later she would successfully fire her first trial torpedo (without warhead). On 5 December she submerged at 7.5 m; twenty days later she would pass her first non-static dive test, sailing at a steady depth of 9.5 meters, and later in 1890 maintaining the same depth and sailing underwater for one hour. The submarine had reach a maximum depth of 30 meters in trials.

On 25 June that year she made two simulated engagements on the cruiser "Colón", one at day and other at night. At the daylight trial the submarine was unable to attack the cruiser, as her optical turret was spotted less than 1000 yards away from the cruiser, which had 200 civilian and military guests, and obviously expected to see the submarine, a fact that angered Isaac Peral.The simulated night attack was successful. The staff that evaluated the trials of the submarine submitted a report, considering speed and range insufficient, being especially critical about the failure of the submarine in daylight attack and its electric motors. However, overall the report was positive, and a second submarine was ordered, again under the direction of Isaac Peral but also managed by several naval departments. Peral designed a 30-meter submarine of 130 tonnes, imposing the condition of choosing the yard where the submarine would be built and the choosing the team. These conditions were not accepted by the authorities, who considered this a refusal of Peral to build the submarine. Finally they ordered Peral to return the submarine to the La Carraca yard where she was built. On 11 November 1890 a decree set the end of the projects of underwater navigation in the Spanish navy.

Similar figures of performance were only attained about a decade later in other countries. The speed and endurance of the Peral would still hold to Second World War standards.

Isaac Peral, frustrated, retired from naval active duty in November 1891 and died in Berlin in May 1895 of meningitis, after a medical intervention to cure the cerebral tumor he had been suffering for some years. In the same year John Philip Holland would mark a major step forward in submarine design, designing for the first time a mixed internal combustion/electric propulsion that would solve the problems of limited range of batteries.

The first Spanish navy submarine which was built 22 years later was named after Peral. His submarine was scrapped in 1913, but was salvaged and sent to Cartagena, homeport of Spanish submarine flotilla, where she was conserved until the seventies, when she was handed over from the navy to the city.

References

* Miller, David, 2002, "The Illustrated Directory of Submarines of The World", MBI Publishing Company, ISBN 0-7603-1345-8