Earlier quoted context omitted.
Even 70+ minutes is dubious for a small liquid fuelled quad-copter. It's more likely there were multiple drones swapping in and out.
They specifically said it was not a quadcopter. It was probably a fixed wing craft.
In the report[1] they explicitly list it has as a rotocraft with an unknown (-1) number of rotors. They also list the UAS type as "quadcopter". At one point in the article they describe it as "hovering"
[1] https://s3-us-west-2.amazonaws.com/the-drive-cms-content-sta...