Sky-engines were a type of flying machine built by the gnomes before the First War. Both sky-engines and whirligigs were considered suitable for scouting.
This article or section includes speculation, observations or opinions possibly supported by lore or by Blizzard officials. It should not be taken as representing official lore.
Judging by the name, "sky-engines", and the fact they are considered separate from whirligigs, they seem to be implied to be airplanes rather than helicopters. Some unnamed flying machine models seen during the second warmay be sky-engines. They appear to have weapons.