Aviatsia i Vremya Magazine (February/March 2012) had a couple of articles about the development of Yak-104 ...
Yak-104 - Design started February 1957, mock-up completed August 1957. Originally proposed with R5-300 engine but ended up with RU29-300. Development authorised by SovMin resolution July 1958, same time as TS-11 and L-29 were being developed.
Yak-104D - A design with refinements to fuselage, wing, undercarriage and cockpit as a result of instructions from A.s. Yakovlev. This model was redesignated Yak-30.
- Yak-30 - Originally Yak-104D. The first prototype "30" completed May 1960, second "50" in July, both at the OKB. Flight testing began 20 May 1960. Two other prototypes built "80" and "90". Cancelled due to VVS purchase of L-29. Example "80" currently flying in Russia after a rebuild. One of the prototypes was at Monino in the late 1990s.
- Yak-30M - One prototype converted as an airborne control aircraft in 1962 and undertook unmanned take-offs and landing. Also referred to as the Yak-30KP. Part of the Yak-25RV-II testing programme.
- Yak-30V - VTOL design project, terminated when work on the Yak-36 began.
Yak-104PS - A design for a single seat sports aircraft started in 1959. Derived from the Yak-30, it was later redesignated Yak-32.
- Yak-32 - Prototype "32" rolled out 13 October 1960. Two more prototype followed "60" and "70".
- Yak-32Sh - Proposal for the type to be fitted with weapons racks as a ground attack fighter in 1961.
- Yak-32P - Project authorised by MAP directive in 1971 to restore one example as an advanced trainer.
See
http://www.secretprojects.co.uk/forum/index.php/topic,4180.msg32969.html#msg32969 for more details of the Yak-30/32
The general view of these articles was that the Yakovlev trainer was a better fit to the VVS requirement for a jet trainer but the decision to acquire L-29's from the Czech was based on politics rather than requirements.
