Interesting step by Iran. The RQ-170 has been copied full scale but due to the lack of suitable jet engines they went for a smaller variant of it which should have following changes beside the size:
- Limited stealth capability, the use of a flying wing design gives a huge lift and hence fuel efficiency compared to conventional design like the S-129.
- I'm quite sure that the piston engine of the S-129 is used instead of Karrars Toloue mini jet engine or even something more advanced such as the Soumars/Kh-55 mini turbofan. This would reduce the speed significantly but make it much less expensive to operate and build. A flying wing UAV with a prop propulsion would make it a tactically useful system and all necessary technologies are there in Iran. A prop propulsion would also further reduce its stealth capabilities.
- It apparently lacks a landing gear so I would think that just like the Karrar it is accelerated by a booster. This would make runways unnecessary and add to its tactical benefits. The use of a catapult system is also possible.
The technological hurdle at the moment is the lack of a larger turbofan that can be serial produced. The owj engine without afterburner would do the job but at much decreased range. Once Iran gets a turbofan into seril production we can expect serial produced RQ-170s with space for a weaponbay or a larger variant with twin engines as heavy UACV bomber. A system like that could then make full use of the stealth capabilities given to Iran by the RQ-170.