It’s the deepest Ukrainian drone strike of the war, so far
A month after Ukraine began bombarding targets inside Russia with explosives-laden sports planes modified for remote flight, one of the do-it-yourself drones has struck an oil refinery in the city of Salavat, more than 800 miles from the front line of Russia’s wider war on Ukraine.
It is, by far, Ukraine’s longest-range raid—and an escalation of Ukraine’s deep-strike campaign targeting Russian refineries, factories and strategic military sites.
And it’s at least the fourth attempted deep strike involving Ukraine’s sport-plane drones. Videos shot by people on the ground in Salavat clearly depict the wide straight wings, fixed wheels and propeller that are typical of an inexpensive sport plane, the kind a middle-class pilot can build at home from a kit costing as little as $90,000.
Total weight is crucial for how far a plane can fly. So - Pilot weight + Payload weight needs to be considered.
In terms of damage, if you hit the right spot without redundancies you can shut down or severely limit operations of a plant even with only a small material damage. Even if there is no visible damage, reducing the structural integrity of pressure pipes and the like can force a shutdown of that equipment until the damage is properly investigated.
In 2019 Houthis successfully attacked two Saudi refineries with a small swarm of drones, forcing a shutdown.
https://en.wikipedia.org/wiki/Abqaiq–Khurais_attack