The HESA Qasef-1 is an offshoot of the established Ababil line of Iranian developed and produced Unmanned Aerial Vehicles (UAVs) detailed elsewhere on this site. Iran has deliberately moved to strengthen its expertise in the field of military-level drones and the Ababil is a product of this initiative. It has been in service since the volatile 1980s and has been consistently evolved into more capable, potent forms. One byproduct of this undeterred work is the "Qasef-1" which is believed to have been in operational service since sometime in 2016.
NOTE: It is actively debated whether the Qasef-1 is the direct product of local Iranian industry or the product of in-the-field modification of the Ababil-2 production form by Houthi rebels operating actively in Yemen. For the purposes of this article, it is assumed that local Iranian industry has driven this development.
Unlike other Ababil forms, the Qasef-1 is an expendable "loitering munition", tracking for ground targets (ground-based control is via GPS), engaging on-command, and expending itself in a suicidal action. The air vehicle adds a 66lb 30kg) explosive warhead to the mix which provides the detonation / damage capabilities of a conventional drop bomb at much reduced cost - making the Qasef-1 an excellent budget attack weapon and perfect for rebel-types seeking to make some noise. To this quality add the fact that drones are small and slow enough to evade traditional radar, giving them an inherent "stealth" quality.
The physical characteristics of the aircraft, based on captured specimens and displayed by Saudi officials, include a centralized, tubular fuselage, rear-set mainplanes (featuring little sweepback), and foreplanes for added control. Vertical fins are seated at the mainplanes at the rear of the aircraft. The fuselage holds all of the pertinent operational equipment included the engine, optics set, fuel stores, and avionics. The engine is installed at the extreme end of the fuselage and drives a multi-bladed propeller unit in "pusher" fashion. Since these air vehicles are designed to be expendable (i.e. no return trip), no undercarriage is necessary, further simplifying construction and reducing cost. Launching of the air vehicle is by ground-assistance, either pneumatic catapult (stand-alone or vehicle-mounted) or jet- / rocket-assisted.
Houthi rebels have been known to use their Qasef-1 drones to directly attack "Patriot" missile station components, mainly the critical radar sections of the arrangement. This represents a considerably enhanced capability for the rebels and a new type of escalation in the long-running Yemeni war. Houthi-directed armed drones have also attacked UAE and Saudi airports as well as key Saudi sections of oil pipeline.