Recent Russian air strikes against Ukrainian cities using Iranian Shahed-136s resulted in one of the UAVs having engine trouble and landing intact. This enabled Ukrainian and foreign investigators to scrutinize the construction of the Shahed-136. Most of these that run into engine problems crash and explode. This one had been given contaminated fuel that caused the UAV to gradually descend and hit the ground without enough impact to set off the warhead contact fuze.
Obtaining an intact aircraft allowed for a more thorough inspection to be done. The MD-550 engine was built in Iran and it was confirmed that this was indeed an illegal copy of the German L-550 engine. Iran had obtained one of these engines in 2006 and used it in several UAVs, including Shahed-136. The L-550 entered production in the 1980s and was a popular engine for ultralight aircraft and UAVs. Legal copies of the L-550 cost about $15,000 each. That means a Shahed-136 costs about twice the original estimate of $20,000 each. A Shahed-136 weighs 200 kg (440 pounds) and is armed with a warhead containing 30 to 50 kg, most of it explosives. That’s not a lot because most cruise missiles carry warheads weighing half a ton (500 kg) or more. The Shahed-136 warhead will damage, not destroy, most structures it hits. Shahed-136 is launched using a rocket motor that gets it into the air and then detaches and falls away.
Iran provides several different warheads, including an anti-tank version. Navigation is via GPS or a remote operator that can be up to 150 kilometers away from the Shahed-136. Top speed is 185 kilometers an hour but using a lower cruising speed range can be over a thousand kilometers. Shahed-136 is reactively slow for a cruise missile and normally flies low and is loud. You can hear it coming and Ukraine developed a cell phone app that allowed people to point their phone at a Shahed-136 and automatically transmit the UAV location to a central command center that was tracking aerial attacks and alerting anti-aircraft units, especially those that used heavy machine-guns, to shoot down the Shahed-136s. Without the element of surprise, Shahed-136 is a very ineffective weapon.
In late 2022 Ukraine accused Iran of supplying Russia with 1,700 Shahed-136s for use as cruise missiles, especially during covert surprise attacks. Ukrainian air defenses have improved to the point where most of the Shahed-136s Russia launches against them are shot down. In one case all the Shahed-136s launched were shot down. This attack was made at night to hit Ukrainian urban electrical distribution systems. Officially, Iran says it is not supplying Russia with Shahed-136s but they continue to be used to the present.