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Overview
The TS-11 Iskra (spark) bis is a Polish jet trainer/ light multirole aircraft. Poland’s first indigenous jet aircraft, it was developed from 1957, first flew in 1960, and entered service in 1964. The A model was the first production variant, and was primarily a trainer with limited armament compared to later models.
Note on engines: the three prototypes were powered by Viper 8s. The first three batches of Iskra As, for a total of 54 aircraft, were powered by the HO-10, a licensed version of the Viper with minor improvements. The fourth and final batch of 15 Iskra As featured the more powerful SO-1 engine. This suggestion will be specifically focussing on the HO-10 powered aircraft as that was the most common powerplant and to differentiate the A from the following Iskra bis B.
^Iskra DF but I can’t find a good image of an A in flight so deal with it
History
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Development
Poland’s first jets were a trio of Yak-17s and 11 Yak-17UTI trainers purchased in 1950. As the Siły Powietrzne (Air Force, from here on abbreviated SP) acquired more jet aircraft (Yak-23s in 1951, production of MiG-15s in 1952) the need for a new basic jet trainer arose. In 1956, project requirements for the new TS-11 (named for lead designer Tadeusz Sołtyk) were laid out- the aircraft was to be of all-metal construction with a low, straight, thin wing, a top speed of Mach 0.8 and a conventional tandem cockpit layout with the student in the front and the instructor behind. The TS-11 was to be armed with a 23mm cannon for gunnery training or to allow the aircraft to operate as a fighter should global war break out.
A full-scale wooden mockup was built in late 1957. This was followed by a static test airframe in March 1959 and three proper flying prototypes from December 1959, all mounting the British Viper 8, acquired from Yugoslavia. The TS-11 made it first flight on 5th February 1960, being publicly debuted on 11th September 1960 in Łódź. The three prototypes underwent extensive testing late 1960 through 1961, proving easy to fly, agile, stable, reliable, and simple to maintain- in short, exactly what you’d want in a training aircraft.
Competition
So in August 1961 when the TS-11 was put up against the Soviet Yak-30 in a competition to become the standard jet trainer for Soviet allies, it dominated, outperforming the Yak in essentially every metric. This would be a massive deal for the Polish aviation industry.
However, there was a third contestant in the competition- the Czech L-29 Delfín. The L-29 was very similar to the TS-11 and nearly matched it in performance, all at a lower cost than the Polish aircraft. Because of this, the L-29 was selected as the standard primary jet trainer, and it and the subsequent L-39 were used by all close Soviet allies- except Poland, who continued forward with the TS-11.
Production and Service
Production of the TS-11 Iskra bis A began in 1964. Production aircraft were fitted with the HO-10, a copy of the Viper 8 with slight improvements that boosted its continuous power to 7.84kN. The first batch of 10 aircraft were handed over for trials in 1964. This was followed by two batches of 22 each in 1964 and 1965 respectively. Finally, in 1967, the last batch of 15 Iskra bis As (powered by the improved SO-1 as mentioned in the intro) entered production.
These aircraft had relatively uneventful service lives in SP service. The Iskra A was the least reliable of the family due to the HO-10, but still had a low accident rate.
The Iskra bis A achieved a series of four closed-circuit speed records for an aircraft in the 3000kg class.
Further Developments
During this period the idea of a trainer/light attack aircraft was becoming very popular. Such an aircraft would provide increased strength in the event of war while being cheaper than separate trainer and light strike aircraft. Additionally, combat-capable trainers made training more realistic, allowing live-fire of actual weapons in service instead of simply simulators.
To this end the TS-11 Iskra bis B was developed with four underwing hardpoints for carrying ordinance, for training or combat. This aircraft had the SO-1 engine initially, later replaced by the more reliable but equally powerful SO-3.
This was followed by the unsuccessful photoreconnaissance Iskra bis C, and finally the Iskra bis D with a more powerful SO-3B engine. The bis D was developed into the bis DF with further refined SO-3W engine and reconnaissance capabilities. The D and DF were the only Iskra models to see export with 76 purchased by the Indian Air Force.
Finally in 1991 small numbers of DFs were rebuilt to the navalized Iskra bis R standard.
One interesting prototype model of the Iskra was the BR 200, a single-seat dedicated attack aircraft that wasn’t accepted into service due to the availability of the superior Su-20.
Almost Immortal Spark
The TS-11 had an extremely long service life, the longest for any armed single-engine jet in service of the country of origin. Simply, nothing could replace it. The first attempt to build a successor came with the TS-16 Grot of 1963, a supersonic aircraft (only the second supersonic trainer aircraft design in the world, preceded only by the T-38). This aircraft never saw production due to ballooning costs. The next attempt to replace the TS-11 came in 1976 with the I-22 Iryda. The Iryda was a subsonic twin-engine aircraft comparable to the Alpha Jet. This aircraft was actually produced and even entered service, and proved reliable, agile, and easy to fly just like the Iskra, while having substantially improved performance. However, the end of the Cold War and subsequent budget cuts killed the I-22 program in 1999 after only 28 built and 5 years of service. The I-22 would be the last indigenous Polish combat aircraft design. The next attempt to replace the TS-11 came in 2010, with the SP looking to purchase and license-produce the L-159 Albatros 2. This purchase was not pursued. The TS-11 would only begin being replaced in 2017, with the controversial purchase of the M-346 Bielik. While originally offered the M-346LCA, a modified version the the M-346FT, Poland instead opted for an unarmed version of the aircraft. This meant that many pilots were being deployed to their operational units without any actual weapons training, a significant issue only resolved in 2023 with the purchase of the FA-50GF. The final TS-11s were retired in 2021, 64 years after their first introduction.
Specifications
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Airframe
Length: 11.25m
Span: 10.60m
Height: 3.50m
Empty Mass: 2,560kg
Loaded mass: 3,734kg
Wing Area: 17.50m^2
Crew: 2
Propulsion
1x HO-10 turbojet
Max thrust (dry): 7.84kN
Max thrust (WEP, 180s): 9.21kN
Internal Fuel: 1,200L across 4 self-sealing tanks
Flight Performance
Max Speed: 720km/h (Mach 0.58)
Climb Rate (presumably without WEP): 11m/s
Armament
1x NS-23 23mm cannon
23x115mm
115 rounds
600 RPM
720m/s
or, interchangeably (can be swapped out in <30 minutes)
1x NR-23
23x115mm
150 rounds
900 RPM
720m/s
I’d have the NS-23 stock and NR-23 as a Rank I/II modification
Systems
RW-2 radar altimeter
Engine fire suppression system
KAP-3 ejection seats
The TS-11 Iskra bis A in-game
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The TS-11 has pretty poor performance for an aircraft of its time because of its role as a trainer. However, it performs decently compared to first-gen jets. The Iskra would be a central part of a Polish air tree, helping to bridge the gap between wartime western equipment and post-cold-war western equipment.
Pros:
- Agile
- Decently fast
- Moderately powerful engine
Cons:
- Abysmal climb rate
- Limited armament- NR-23 is an effective cannon but only a single cannon is rather poor
- No suspended armament unlike later models
Placement in a hypothetical Polish tree
Gallery
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Images of Iskra As specifically are difficult to find because of their short service life compared to other models.
Besides this blue display scheme,
Iskra As were likely mostly bare metal like the rest of the models
Also with a several variations of nose and tail colour used to indicate what unit the aircraft was assigned to
The HO-10 engine, an improved, unlicensed copy of the Armstrong Siddeley Viper 8
TS-11s are sometimes fitted with a cartrige collector and sometimes not
Inside the front and rear cockpits. Note avionics and instruments were continually upgraded during service so these images more so give an overall layout of the cockpits vs exactly how they would appear in-game
Sources
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Polskie Skrzydła- Polish Wings 36 TS-11 Iskra- Dariusz Karnas and Artur Juszczak
PZL TS-11 Iskra. 2008. - Polot
PZL TS-11 Iskra. 2009. - Polot
PZL TS-11 Iskra. 2010. - Polot
PZL TS-11 Iskra. 2011. - Polot
PZL-Mielec TS-11 Iskra two-seat low-wing jet trainer
Also check out the other members of the TS-11 family!
Iskra B
Iskra C
Iskra D
Iskra DF
Iskra R
Iskra BR 200