Editing Stall (fluid dynamics) (section)

===Characteristics===
Different aircraft types have different stalling characteristics but they only have to be good enough to satisfy their particular Airworthiness authority. For example, the [[Short Belfast]] heavy freighter had a marginal nose drop which was acceptable to the [[Royal Air Force]]. When the aircraft were sold to a civil operator they had to be fitted with a stick pusher to meet the civil requirements.<ref>Tester Zero One – The making Of A Test Pilot, Wg. Cdr. J.A. "Robby" Robinson AFC, FRAeS, RAF (Retd) 2007, Old Forge Publishing, {{ISBN|978-1-906183-00-4}}, p.93</ref> Some aircraft may naturally have very good behaviour well beyond what is required. For example, first generation jet transports have been described as having an immaculate nose drop at the stall.<ref>Handling The Big Jets – Third Edition 1971, D.P.Davies, Civil Aviation Authority, p.113</ref> Loss of lift on one wing is acceptable as long as the roll, including during stall recovery, doesn't exceed about 20 degrees, or in turning flight the roll shall not exceed 90 degrees bank.<ref>Test Pilot, Brian Trubshaw With Sally Edmondson 1998, Sutton Publishing, {{ISBN|0 7509 1838 1}}, p.165</ref> If pre-stall warning followed by nose drop and limited wing drop are naturally not present or are deemed to be unacceptably marginal by an Airworthiness authority the stalling behaviour has to be made good enough with airframe modifications or devices such as a stick shaker and pusher. These are described in "Warning and safety devices".