For an airship to remain stable while shedding weight, it must be able to compensate for this delivery by taking on an identical weight in a very short time. Barry Prentice, a Canadian academic who heads the Isopolar Institute, which brings together North American airship companies, believes that "it's a bit like trying to put both legs into your pants at the same time, while remaining upright. Dropping a load on the ground and compensating for it by bringing up ballast, I don't know how Flying Whales intends to do that . "