A kind of sail
used in kite
s and paraglider
s which needs no spar
s to produce a stable lift generating surface.
Ram-air canopies were invented and first flown by kite designer Domina Jalbert. They have a wing shaped 'envelope' of cloth, which is kept inflated and in shape when flying by the bridling (lines attached to the undersurface), vertical ribs (extra surfaces which are are stetched between the upper and lower surfaces and divide the envelope into cells) and holes along the leading edge.