These were used in the Weir W2, W3 and W4 autogiros. Others feature unusual flight configurations, such as ornithopters, helicopters or autogiros. Brooks, Peter W. Cierva Autogiros&colon; the Development of Rotary-Wing Flight. From this point on, Pitcairn focused on autogiros. Helicopters and Autogiros; A History of Rotating-wing and V/STOL Aviation.