Iran's newest gunship helicopter, unveiled Wednesday, might look awfully familiar to aviation historians. And it's not unique in that regard. Almost all of Iran's "new" weaponry – including jet fighters, 'copters, warships, tanks, missiles and other equipment – is a copy of a much older American, British, Russian, Chinese or North Korean design.

But that doesn't mean all of Tehran's weapons suck. Far from it. While some of the sillier Iranian gear is obviously meant mostly for fleeting propaganda purposes, the main hardware is grounded in experience and hardship. Driven by desperation and shaped by the isolation that comes with widening external sanctions, Tehran's copycat arsenal could contain a few nasty surprises for the U.S. and its allies in the unlikely event that tensions over Iran's nuclear program come to blows.

For one, low-tech weapons force the users to fight creatively. "There's a chance they'll catch us by surprise," Air Force Lt. Col. Dan Ward, an engineer and acquisitions expert and prolific writer (.pdf), tells Danger Room in an e-mail.

Equally importantly, Iran's tendency to produce slightly evolved versions of classic weapons means it doesn't spend billions of dollars developing, say, a brand-new warplane and all its associated technologies from scratch. "One of the benefits of this 'frugal innovation' approach is that it allows a greater quantity of aircraft to be purchased (as opposed to the infamously small fleet of F-22s, for example)," Ward explains.

The Iranian air force maintains around 500 manned warplanes, making it one of the biggest in the region. But it's not just planes benefiting from Tehran's secondhand weapons-development strategy. The Toufan 2 attack helicopter, which first appeared in public during a military exercise this week, is an upgraded version of the American AH-1, a Vietnam War-era copter that Iran originally purchased from U.S. manufacturer Bell back in the 1970s, before the Islamic Revolution transformed Tehran from America's close ally to one of its most bitter enemies.

Aviation blogger David Cenciotti notes what appear to be the Toufan 2's improvements over the original American-made 'copter. "The main difference from the version already in service is the electro-optical surveillance and tracking system that is believed to use FLIR (Forward-Looking Infrared) technology, visible electro-optical imagery, as well as laser designation and illumination to provide target identification, ranging and tracking capability."

That approach – adding new electronics to an old, sometimes copied, vehicle – is characteristic of Iran's arms industry. Among other hardware, Iranian technicians have also reverse-engineered and enhanced: the American F-5 jet fighter; American, British and Russian tanks; British patrol vessels; and Chinese and North Korean ballistic missiles.

The Iranian version of the F-5, known locally as the Saeqeh, made the news a few years ago when state media claimed the obviously non-stealthy jet could evade enemy radar. The government-controlled press has made equally risible boasts regarding the Iranian navy's new Jamaran "destroyer," which is in fact a copy of a copy of a decades-old British light frigate, albeit with relatively modern weapons based on U.S. designs. Tehran's Zulfiqar tanks and Dehlaviyeh missiles are likewise knock-offs.

Iran also copies American Unmanned Aerial Vehicles – or so Tehran claims. Iran's homemade drones (there are lots of them) could combine broad design elements taken from U.S. UAVs that have crashed, with surprising frequency, in or near Iranian territory in recent years. Fitted with electronics built at home or sourced from Iran's few remaining allies, new hybrid drones might look like knock-offs but boast unique abilities. Unexpected sensor combinations, for instance.

Iranian lawmaker Avaz Heidarpour said last month that his country had figured out how to build its own versions of a U.S. stealth spy drone that crashed on the Iran-Afghanistan border in December 2011. There are good reasons to doubt that, even with the RQ-170 Sentinel's wreckage to study, Tehran's engineers possess the technical know-how to perfectly duplicate the radar-absorbing materials that are one key to American stealth warplanes.

But considering Iran's decades of experience tearing down, copying, manufacturing and upgrading old designs of foreign origin, it's not inconceivable that a rough approximation of the Sentinel – emphasis on "rough" – could soon appear in the skies over Iran and its neighbors. If history is any guide, the Iranian done-clone could add customized systems to an airframe modeled on the lines of the crashed RQ-170.

Meanwhile, Iran is also enhancing old U.S.-built F-4D Phantom fighters. Originally acquired from the American plane-maker McDonnell Douglas in the early 1970s, the twin-engine jets quickly fell behind the latest F-15s, F-16s and other U.S. warplanes that entered service in subsequent decades. Blocked from buying new jets, Iran has begun upgrading around 10 of its remaining F-4Ds plus dozens of newer F-4Es with new radars, radios, cockpit displays and missiles sourced from China.

The F-4s aren't terribly maneuverable and they're anything but stealthy, but with new sensors and weapons they could still put up a fight. Germany, Turkey and Japan certainly think so: they, too, still use F-4s fitted with new gear. And Iran's lack of cutting-edge equipment means its pilots must adapt, improvise and emphasize skill and tactics over technology.

"It's been said the greatest swordsman in the world has nothing to fear from the second greatest swordsman," Ward notes. "He should be worried about some idiot who's never picked up a sword before and acts in a completely unpredictable manner. Iranians flying refurbished and upgraded F-4s will, out of necessity, fly them differently than a pilot in a more advanced fighter."

"We'll learn and adapt, of course," Ward adds, "but that first hit could hurt more than we think."