Kraków 2017-08-02
Jak-17 UTI Agata
Two-seater combat aircraft.
Part 01
Currently (2017) the most modern combat aircraft in the world are designed only as single-seater machines. Two-seater versions of combat aircraft that were called training-combat aircraft are no longer being built. Projects already implemented and put into service, such as F-22 and F-35, confirm this rule. This tendency results from several basic premises. First, computer technology is already at such a level that only one soldier is needed on board. Secondly, this soldier is trained using modern simulators, which not only drastically reduces costs, but allows for much longer and multi-faceted training. Thirdly, in a real armed conflict we need fewer pilots than for two-seater aircraft. Currently, the norm is 1.5 pilot for one fighting machine. So with a fleet of 50 F-35 aircraft, 75 pilots are needed. In turn, 150 pilots are needed for 50 F-14 Tomcat fighting machines. The difference is huge. Let’s not forget that training a pilot-soldier is expensive, long, and keeping him in service is also complicated. This has not always been the case. In the 50s of the twentieth century, in order to effectively train a combat aircraft pilot, he also had to be trained in the air on two-seater (two-way) versions of combat aircraft. The best examples are US warplanes: F-100, F-104, F-105. They all had binary versions.
And how was it in Poland? Poland is a good example because we had a well-developed aviation industry and we were able to address the most urgent needs of the Polish Army.
Jak-17 UTI Agata
When in the 40-ies of the twentieth century in the world began to develop, like mushrooms after rain, the construction of turbojet aircraft, many countries introduced them to armament. Poland joined only in 1950. Not the time and place to consider why this happened. At the beginning of 1950, we purchased the first batch of Jak-17 fighters consisting of three machines. The planes were brand new. These machines were delivered by one rail transport to Radom and placed in one of the heavily guarded hangars. Each of the aircraft was partially dismantled and placed in crates. Their assembly and acceptance flights were to be carried out by Soviet technicians and pilots. The first Polish Jak-17 aircraft was assembled in July 1950. Lieutenant Colonel Wasyl Gaszyn, a CCCP citizen serving in the LWP (Polish People’s Army) from 1943, from the school in Grigoriewsk, was preparing for training flights. He was the first to demonstrate this unique aircraft at the time to selected representatives of the army and civil aviation. Subsequently, the plane was planned to be presented to the public at the Aviation Day celebrations. In the first decade of August 1950, wok Lt. Col. Colonel Wasyl Gaszyn began intensive training flights preparing for the shows. A tire was damaged during one such flight. This meant the end of training flights. At that time, the decision was made to replace the entire wheel with one of the unassembled aircraft stored in Radom. For this purpose, Lt. Col. Wasyl Gaszyn together with Ensign Z. Pietrucha by plane Po-2 flew to Radom. There, with the help of an organized team of technicians and cadets, they pulled one chest out of the hangar and dismantled the wheel from the right panel. They took them to the Po-2 plane and flew back to Warsaw. The wheel was mounted in Jak-17 and training flights were resumed. This method of repair by technical cannibalism was not uncommon in CCCP aviation. The Jak-17 aircraft that Wasyl Gaszyn demonstrated was not strictly a Polish aircraft. It was a machine rented from the Soviet air unit 159. PLM in Poland, stationed at Brzeg Airport, near Opole.
In July 1950, the Air Force Command sent a group of 4 pilots to train on a new type of aircraft; Lt. Col. Wasyl Gaszyn (Soviet adviser from the Air Force Command), Lt. Col. Aleksander Markow (Soviet adviser from the Officers’ Aviation School in Dęblin), Capt. Andrzej Rybacki from the 1st PLM (fighter regiment), see Kazimierz Tanana from the 2nd PLM. The training was fast. Capt. pilot Andrzej Rybacki and lieutenant pilot Kazimierz Tanana made their first independent flights in the first days of August 1950, and each of them weaved 6 hours on turbojets by the end of the course.
At the turn of 1949/1950 the possibility of launching the license production of Jak-17 aircraft by the domestic aviation industry was considered in Poland. In mid-1950, preparations for this production even began, with the third purchased single-seat Yak-17 model available. The aircraft was to be designated PZL Mielec G-1. The works were managed by the main designer of the Mielec factory, Eng. Zygmunt Szczeciński. Production, however, was not undertaken, as it was possible to start production of the Jak-23 fighter with a more modern, half-shell construction. The designation G-3 is provided for the aircraft. And this intention quickly ceased to be valid. In May 1951, as in Czechoslovakia, preparations began for the production of licensed MiG-15.
In parallel, preparations were made in the Rzeszów WSK to license production of RD-10 A engines under the name G-2. These plans were also abandoned. Only 30 copies were made, which were used to drive used Jak-17 W.
It was already known then that training a pilot with average capabilities for a turbojet aircraft would be a bit of a difficulty. The simulator was not thought then, but rather the training and combat version. Such an aircraft materialized in the Jak-17 UTI version. The aircraft also received the designation Jak-17 W, and strictly Jak-17 B (B is the third letter of the Russian alphabet). In Poland he was unofficially, very nicely called Agata.
In 1951, 11 copies of the Jak-17 UTI aircraft were brought to Poland. They were not new aircraft, but they were already operated in Soviet units. The first copies went to Bemowo Airport, where training was carried out. Later, they were deployed to combat units that operated a total of 103 Jak-23 aircraft. The task of the Jak-17 UTI aircraft was to train pilots for single-seat Jak-23 machines, which in Poland did not have a two-seat version. It was a combination of necessity rather than choice, because the planes were not even similar externally. They had slightly different volatile characteristics, and above all other power units. In Jak-17 UTI for Germanic RD-10 A engine with 9.80 kN axial compressor, and for Jak-23 for British RD-500 engine with 15.58 kN radial compressor. Starting the RD-10 A engine was complicated and a bit dangerous. The engine was started on gasoline and only later switched to petroleum. It should be added that in practice, when starting the engine, emergency situations were very common. It was very dangerous when the gasoline did not catch fire and just poured from the exhaust nozzle. Or caught fire, but the engine speed did not increase, and the temperature increased. In these cases, pilots were breaking records for leaving the cabin, because fire and explosion were very likely. The fire extinguishers were moving. Before re-launching, it was mandatory to clean the fuel nozzles to avoid explosion. A group of strong mechanics lifted the nose of the plane up and poured unburnt gasoline from the nozzle. When the gasoline evaporated and the concrete on the stand was dry, the pilot could again take the place in the cabin and start the engine again. However, when the gasoline caught fire and the turbine revolutions began to rise, and the temperature did not rise more than 680 degrees C, at turbine revolutions above 2,000 rpm, the kerosene valve was opened and if it in turn ignited, the gasoline supply was closed and the engine could considered running. On the other hand, the RD-500 engine was started using several switches.
Agata (Jak-17 UTI) was a little easier to fly than the propeller nine (Jak-9). The plane did not lose direction at take-off, and the more powerful engine makes it easier to make figures in the zone. The cab is quite spacious, the visibility from it is great, like in a car and less engine noise. It was also not necessary to constantly manipulate, next to the throttle grip, the R-7 lever – the propeller stroke, or guard the covers of the oil and water cooler. There is only one indicator of the exhaust gas temperature.
The new engine required the pilot to learn certain habits. For example, the movements of the lever to increase the engine speed had to be much slower. The reciprocating engine responds to gas shift almost immediately. In a turbojet engine, this is much slower, but increased thrust accelerates the plane much faster. During evolution and pilot figures, there are large overloads, significantly exceeding similar phenomena on a propeller plane. However, the difficulty of piloting was the need to constantly observe the fuel pressure indicator. With a drop below 2.0 atm, which could have happened with full gas clothing, the engine may have stopped. And re-launching in the air remained in the realm of theory.
However, the main disadvantage of the aircraft was a very small fuel supply, sufficient for a quiet 20 minutes of flight, maximum 28 minutes. Of course, without additional fuel tanks. In practice, two circular flights, 12 minutes or a short zone of no more than 15-17 minutes were performed without refueling.
What did the pilots say about the Jak-17 flight? – "Initially, after taking a seat in the cabin, I felt strange. The long nose and propeller blade was missing from the front, but I quickly got used to it, because the great visibility overshadowed all reminiscences. Start a dream. You can let go of the reins and it will not go down the step. At 140 km / h (VR), the wheel rises and the maximum speed is 700 km / h. When the silence turns, just a slight whistle of the turbine. There are no deviations in the vertical figures, there is no powerful propeller gyroscope throwing the plane left to right. In a word, I feel wonderful in the air. And after these flights, it seems to me that the jet plane is the one I’ve been waiting for, which is my destiny. "
The introduction of turbojet aircraft into the armament also resulted in the introduction of a new regulatory attire in the form of a jacket, trousers and shoes made of leather. The pilot in such clothes looked very elegant and distinguished himself significantly from other soldiers. In addition, the diet of jet pilots was significantly higher. This appreciation of the pilots made them a kind of elite.
Three Jak-17 single-seat aircraft could not constitute any combat value. That is why they were mainly used to improve the piloting technique and, above all, to learn how to shoot for first pilots. Only the Jak-17 had shooting equipment.
In 1957, two Jak-17 UTIs were transferred to the Institute of Aviation in Warsaw. The first of them from nb 7 (1) was delivered by flight on January 21, 1957, and the second of them nb 4 was also delivered by flight on March 1, 1957. Both machines were piloted by Eng. Andrzej Abłamowicz, the first Polish civilian pilot who sat at the controls of a turbojet aircraft. The Jak-17 UTI nb 4 aircraft was registered at IKCSP and received the SP-GLM mark, and most of the test flights were carried out on it. The aircraft was used to learn piloting and training future pilots of the emerging training aircraft TS-11 Iskra. Other flights were used to check steering and stability as well as performance, e.g. maximum flight time. The last flight on it was made on February 3, 1960, and in 1963 it was subjected to being drafted for museum purposes. At this time, checkers were painted on registration of SP-GLM. In August 1964 he was already in military colors and with a nb 02 exhibit of the Museum of Aviation and Astronautics in Krakow (Rakowice, Czyżyny). After years, the museum changed its name to the Polish Aviation Museum, and the aircraft is unique on a global scale to this day, because no other copy has survived. In 2015, the aircraft underwent a renovation, during which the colors of the Institute of Aviation were restored.
Meanwhile, the beginning of the 50s of the 20th century, the geo-political situation in the world has changed. A war broke out in Korea and the Soviets already had nuclear weapons. Muscovites created a new military concept. The new concept imposed on Poland also resulted in breaking the balance between the development of the economy and the strength of the army. In two years (1951–1952) greater military strength and numbers were to be achieved than planned in the plans for 1949–1955. Because of these changes, these 3 Yak-17 fighters that were new and 11 Yak-17 UTIs that were new were used, it remained the only aircraft of this type in Poland. The delivery program for 103 Yak-23 aircraft has been completed and we have been given a new technique in the form of MiG-15 aircraft.
Written by Karol Placha Hetman