Aero L-29, Part two, Bulgarian and Czechoslovak users

Answering to a sizable requirement for a common jet-powered trainer that could be used by the nations of the Eastern-Block. Aero decided to bid with their own project with a view to suitably satisfying this demand.
On 5th April 1959 the first prototype, name XL-29, flew for the first time. It was selected to be the primary trainer for many Warsaw Pact countries so it was massly delivered from the 1960s onwards.
During the late 1950s the Soviet Air Force started to look for a jet-powered replacement for its piston engined trainers. Over time, the requirement study was widened towards an aircraft capable of overtaking many roles at the same time and could be easily adopted by many Eastern Block countries. Around the same time, Czechoslovakia had been also developing its own jet-trainer that would replace their propeller-powered trainers. To answer those demands, Aero developed a new aircraft, designed by engineers Z. Rublic and K. Tomas. Their work was centered upon a new design based on versatility that could carry the pilots through every stage of training programme as well as frontline duties.
The concept was to create an easy-to-build and easy to operate aircraft. Therefore both simplicity and ruggedness were stressed during development process, leading to the adoption of manual flight controls, large flaps and perforated airbrakes placed on the fuselage sides. Aerodinamically it was designed to be stable and docile. Thanks to that decission, the type was enviably safe. It was able to operate under austere situations such as take-off from grass, sand or unprepared fields. On 5th April 1959 the first prototype, named as XL-29 and powered by a Bristol-Siddeley Viper engine flew for the first time. The second prototype flew shortly thereafter and was powered by the Czech designed M701 engine, which was used subsequently in every L-29.
During 1961 a small pre-production batch was tested against the Polish PZL TS-11 Iskra and the Soviet Yakovlev Yak-30, which were the main rival submissions in the Warsaw Pact main trainer. Shortly after of the completion of the fly-offs, the L-29 was selected as a winner. According to some authors, that outcome caught by surprise to several observers. Regardless of the result, Poland chose to continue the development and production of the PZL TS-11 and the remaining Warsaw Pact and Eastern Block countries adopted the L-29 as their main trainer, under the agreements of the COMECON.
During April 1963 full-scale production of the L-29 started. A total of approximately 3600 exemplars were manufactured on an 11 year production run with some sub-variants being made like the L-29A Akrobat which was a single-seat aerobatics version, a dedicated reconnaissance variant, the L-29R with cameras installed in the rear cockpit position was developed but it was cancelled in 1965. A wide variety of optional armament could be installed in some models like a detacheable gun pod or a pod containing four missiles underneath the wings.
Regarding the drawing, the Aero L-29 was supplied to the Bulgarian Air Force during the 1960s and became its main trainer until the late 1990 when it was completely replaced. The L-39 commenced to replace the type during the late 1970s and for the late 1990s the L-29s was active only with the Aerobatic team.
It was also the main trainer of the Czechoslovak Air Force until it was replaced by the L-39. However, the type was kept in active service until the late 1990s. Apparently on 16th July 1975 a Czechoslovak Aero L-29 shot down a Polish civilian biplane trying to defect to the west.

Sources:
1. https://en.wikipedia.org/wiki/Aero_L-29_Delfín
2. https://en.wikipedia.org/wiki/Bulgarian_Air_Force
3. https://en.wikipedia.org/wiki/Czechoslovak_Air_Force

Mikoyan-Gurevich MiG-15UTI, part eleven, Other European users

The MiG-15UTI served all across the globe, and it was also used by the following countries:

• Armenia: When the country was declared independent in 1991, some UTIs were left behind. They were incorporated into the newly created air force and were used in the Nagorno-Karabah war in the light-bomber role in 1992. All of them were presumably lost in that war. As we couldn't find graphical evidence of the type serving with the Armenian Air Force, the drawing should be considered as speculative.
• Bulgaria: The MiG-15UTI became the main trainer aircraft for the Bulgarian People's Army Air Force in the early 1950s when they were bought from the USSR. They served alongside other types like the Aero L-29 or the Aero L-39 until the fall of Communism in 1989 and even beyond as the type was still in active service in 1992. However, it was retired shortly after and replaced by the L-39 and the Pilatus PC-9. 
• Chechen Republic of Ichkeria: The Chechen National Guard Aviation had at least one MiG-15UTI that received the Chechen roundel. However it was destroyed on the ground during the first hours of the Chechen War in 1994. 
• Finland: In 1954 the MiG-15 was offered to Finland by the USSR, but the Finnish Air Force wasn't interested in the type, however, some years later, in 1962, as they needed an intermediate trainer before completing the transition to the MiG-21F-13, four MiG-15UTIs were ordered. In spite the UTI's good flying characteristics, the UTI didn't handle very well on ground and, as it didn't meet the demands of the Finnish Air Force, it wasn't used very much. It served until 7th February 1977 when it's last flight with the Finnish Colours took place.
• Romania: The Air Force of the People's Republic of Romania imported a total of 60 both Aero CS-102 (the Czechoslovak license-built MiG-15UTI) and MiG-15UTIs from 1953 until 1960. Given to the UTIs good flying characteristics and robustness, they were in service until 1992 making it, with more than 40 years, one of the most longeve aircraft to ever serve in the Romanian Air Force.

Sources:

1. https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-15

2. https://en.wikipedia.org/wiki/Armenian_Air_Force

3. https://en.wikipedia.org/wiki/Bulgarian_Air_Force

4. https://en.wikipedia.org/wiki/Chechen_National_Guard

5. https://en.wikipedia.org/wiki/First_Chechen_War

6. https://www.ilmailumuseot.fi/tuotteet.html?id=20171/255089

7. http://www.aripi-argintii.ro/aparatdezbor.php?p=24 (translated)