Crescent wing
The planform attempts to reduce several unpleasant side-effects of the swept wing design, notably its tendency to "pitch-up", sometimes violently, when it nears a stall.
As an aircraft enters the transonic region close to the speed of sound, the acceleration of air over curved areas can cause the flow to go supersonic.
Most transonic designs use sweep for this reason, allowing them to use a wing that is thick enough for practical internal storage without incurring a heavy wave drag penalty.
If one desires to keep the critical Mach number close to constant on such a design, the thinner outboard sections of the wing should have less sweep than the thicker root.
When considered over the entire width of the wing, this can greatly reduce the spanwise flow, and thereby lower the speeds where the tips stall.
This means the loss of lift occurs closer to the center of gravity, and thereby reduces the magnitude of the pitching forces.
In the case of a swept wing, because these loads are rear of the mean chord, this upward force becomes a torque around the spar, causing the tips to rotate tips-down.
However, it does set a minimum torsional strength requirement which may be higher than would otherwise be needed due to the crescent shape's lowering of the maneuvering loads, thus potentially offsetting this advantage.
During its brief career it showed a tendency to pitching oscillations and, on 26 August 1951, this was observed to occur increasingly violently before the aircraft broke up in the air.
Early versions of the Avro Vulcan had straight leading edges, and these displays problems at high transonic speeds.
The profile and shaping of the crescent wing was subject to considerable fine-tuning and alterations throughout the early development stages, particularly to counter unfavourable pitching behavior in flight.
One unusual flight characteristic of the early Victor was its self-landing capability; once lined up with the runway, the aircraft would naturally flare as the wing entered into ground effect while the tail continued to sink, giving a cushioned landing without any command or intervention by the pilot.
[4][5] The Victor had good handling and excellent performance, along with favourable slow speed flight characteristics and has been described as an agile aircraft, atypical for a large bomber aircraft; in 1958, a Victor had performed several loops and a barrel roll during practices for a display flight at Farnborough Airshow.
[6] The Victor was designed for flight at high subsonic speeds, although multiple instances have occurred in which the sound barrier was broken.
