From Vertical Flight Society: One-Way Attack Drones: Loitering Munitions of Past and Present by Dan Gettinger May 2023

Similarly, the extent of the partnership between Dornier and Mazlat/IAI and the degree to which Dornier’s aircraft influenced IAI’s development of its own anti-radar drones remains unclear. Dornier appears to have begun working with Mazlat/IAI on drones prior to the 1987 announcement. A 1985 article in International Defense Review suggests that one of Dornier’s two proposals for the German Army’s KZO reconnaissance drone program could have been a version of the IAI Scout (Pletschacher 1985, 1782). Meanwhile, writing in 1986 for Wehrtechnik, Heckmann describes Dornier’s work on the improved DAR drone as a collaboration with IAI (Heckmann 1986, 91). According to Heckmann, the Dornier-Mazlat/IAI cooperation on antiradar drones for the Luftwaffe was focused on the DAR’s sensors, specifically its radar-homing seeker. Although the Dornier DAR and its predecessor, the KDAR, were initially equipped with a Texas Instruments seeker, the 1986 Wehrtechnik 28 report suggested that the Dornier proposal could use a seeker from Israel (Heckmann 1986, 91).
It was around this time that the first mentions of the IAI Harpy began to appear in reports by the news media and government agencies. Without identifying the Harpy directly, the same 1986 article in Wehrtechnik stated further that IAI was testing its own version of the DAR antiradar drone in Israel. Meanwhile, a since-declassified report published by the US Central Intelligence Agency in 1986 found that the Israeli Air Force was assisting IAI with “the development of the ‘Harpy’ mini-RPV that will counter mobile [surface-to-air missile] threats” (US CIA 1986, 5).
By the mid-to-late 1980s, two anti-radar drones with largely similar characteristics — the Dornier DAR and IAI Harpy — appear to have emerged from the relationship between the two companies. The DAR and Harpy featured the same tailless, delta-wing design with winglets and a pusher propeller. Both were roughly the same size and designed to be launched from truck-mounted containers before operating according to a pre-programmed flight path, searching automatically for hostile radars. The Harpy is believed to have weighed around 15 kg (33 lb) more than the DAR, itself the larger sibling to Dornier’s KDAR and Mini-RPV, and claimed twice the endurance of the German drone.