flat riser

flat riser

A term used for vertical takeoff and landing (VTOL) aircraft—not helicopters or other rotorcraft—that rise from the ground with the fuselage horizontal by virtue of deflected slipstreams from the propellers and the flaps, by fans, or by vertical jet streams. See vertical takeoff and landing.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved