Iran wants to pretend it is designing original aircraft. Verdict: Fail

Iran has essentially no domestic aircraft industry, whether for civilian aircraft or military. What they produce -- to the extent they produce any aircraft on their own -- is stolen. Otherwise, they buy planes from overseas. Witness the deal with Boeing for passenger aircraft.

When it comes to military aircraft, though, the Iranians are much more limited. Sanctions against the regime's purchase of, among other things, military items -- largely lifted by Emperor Barry I without Congressional approval (or even knowledge) -- have kept Iran from updating its air force since they ousted the shah in 1979. Consequently, they have to lie about domestic aircraft developments.

Case in point: Iran is now popping off about a new fighter aircraft they have "developed." It would appear to be a slightly improved version of the F-5, one of the fighters Iran used to buy from the U.S. when the shah was still in power. It clearly is not a new aircraft, nor even a modern aircraft:

Tehran is keen to produce its own jet fighters—but designing and manufacturing advanced combat jets poses formidable technological challenges difficult for an isolated industrial base to resolve on its own. Nonetheless, the Iranian air force has prominently showcased its development of several domestic fighter jets since the turn of the century, most notably the HESA Saeqeh (“Thunderbolt”), which Iranian media have claimed to be superior to the F-18 Hornet.
But performance specifications and technical details for these aircraft have remained either vague or nonexistent. This may be less due to secrecy than because additional details would likely be unimpressive, because the Saeqeh is a reverse-engineered American F-5 Freedom Fighter with a new tail and upgraded avionics.

The similarities between the two aircraft are obvious. Here is the F-5:

Note the single tail. Now, look at Iran's "new" fighter" hoping to pass for an F-18 knockoff:

Ooh, ooh, twin tails! Must be like an F-18, which is a near-fifth generation fighter (the most modern). Except, no. It's an F-5 with twin tails. Not clear what that even adds to the plane's performance, if anything. And it is important to remember that the F-5 was originally developed in the 1950s -- it hardly qualifies as a modern fighter, even though it has undergone a number of upgrades over the years. Even improved, the F-5 is closer to a third-generation fighter than a fifth-generation craft. If this is what Iran is putting up as its first-line fighter, Iran is in trouble if anyone with semi-modern aircraft scuffles with the Islamic Republic.