Just because we don't have the engine, it does not mean they cannot be working on the rest of the plane. They have been working on these smaller planes for decades now, so I am sure they can now at least attempt to work on something new and heavier. Once they have made it, we can use our current RD-33 engines to test the planes if they have not made their own engine by that time.
I don't buy this notion that we have to wait till we have the engine ready and then start developing the plane, that is such a waste of time.
Design certification and serial production of a engine takes a lot of time. Once a more concrete date of availability can be set, airframe design can also set for that date. I fully agree that a prototype would use a just a mature foreign engine for testing.
However the plan is unknown to us.
- It may mean the engines serial production is still too far away, hence the aerodynamic/airframe team maintains, improves skills and trains new manpower. Imagine a scenario of delay of the engine program that delays a new fighter program and the aerodynamic/airframe team takes such a upgrade program in the meantime to be busy.
- It may mean that the aerodynamic/airframe team is not yet skilled enough to design a mach 2 fighter from scratch and does a lower risk upgrade project.
- It may mean that the the IRIAF for some strange reason believes that this upgrade adds sufficient added capability to the F-7. Hence it rather does that instead of testing a demonstrator for a new fighter. A tech. demonstrator/prototype program adds no short-term capability improvement to the existing fleet.
- It may mean that the aerodynamic/airframe team has splittet in two. A main team that does the tech. demonstrator/prototype program for a new fighter that uses a Iranian engine after testing. A small splinter group of the original team that had completed their projects in that main project and could not be keep busy, hence they moved to such a upgrade program to avoid loosing the team. This case is unlikely but such things happen in industry practice. Sometimes aerodynamic design experts are not need anymore full-time during the prototyping and testing phase. To keep them employed and trained, a new small program is started.
I would say that the serial produced engine is still some years away and design experience on a mach 2 capable airframe too low. Hence this project was started to get within the time plan of a future Iranian fighter and have a capable/mature aerodynamic/airframe team by then.