Sabre dance (aerodynamics)

The Sabre dance is the name given to pitch-up, a particularly dangerous behaviour of swept wings, which became apparent during the development of the USAF F-100 Super Sabre. When a swept wing starts to stall, the outermost portions tend to stall first. Since these portions are behind the center of lift, the overall lift force moves forward, pitching the nose of the aircraft upwards. This leads to a higher angle of attack and causes more of the wing to stall, which exacerbates the problem. The pilot often loses control, with fatal results at low altitude because there was insufficient time for the pilot to regain control or eject before hitting the ground. A large number of aircraft were lost to this phenomenon during landing, which left aircraft tumbling onto the runway, often in flames.

One of the most notorious incidents was the loss of F-100C-20-NA Super Sabre 54-1907 and its pilot during an attempted emergency landing at Edwards AFB, California on January 10, 1956. By chance, this particular incident was recorded in detail on 16 mm film by cameras set up to cover an unrelated test. The pilot fought desperately to regain control during a faulty landing technique,[1] finally rolling and yawing to the right before striking the ground with the fuselage turned approximately 90 degrees to the line of flight. Anderson,1993[2] states the F-100 was noticeably underpowered for its day and had very pronounced "backside" tendencies if airspeed was allowed to decay too much.

The brand new F-100C was flown by Lt. Barty R. Brooks, a native of Martha, Oklahoma and a Texas A&M graduate, of the 1708th Ferrying Wing, Detachment 12, Kelly AFB, Texas. The aircraft was one of three being delivered from North American's Palmdale plant to George AFB, California, but the nose gear pivot pin worked loose, allowing the wheel to swivel at random, so he diverted to Edwards, which had a longer runway.[3] On approach, at a high angle of attack, the fighter exceeded its flight envelope, and, too far into stall condition, lost directional control with fatal results. These scenes were inserted in the movie The Hunters, starring Robert Mitchum and Robert Wagner, in the movie X-15 with actor Charles Bronson playing the unlucky pilot, and in the Made for TV film Red Flag: The Ultimate Game, although in The Hunters and in Red Flag: The Ultimate Game, the aircraft supposedly represented were respectively an F-86 and an F-5E.[4] The incident was also commemorated in the fighter pilot song "Give Me Operations" (set to the tune of the California Gold Rush song "What Was Your Name in the States?"):[5]

"Don't give me a One-Double-Oh
To fight against friendly or foe
That old Sabre Dance
Made me crap in my pants
Don't give me a One-Double-Oh."[3][6][7]

References

  1. ↑ http://www.sabredance.net/officialaccidentreport.htm
  2. ↑ http://ftp.rta.nato.int/public//PubFulltext/RTO/TR/RTO-TR-029///TR-029-$$ALL.pdf
  3. 1 2 Deadly Sabre Dance
  4. ↑ The Sabre Dance
  5. ↑ Ives, Burl, "Burl Ives Song Book", Ballantine Books, Inc., New York, November 1953, page 240.
  6. ↑ mudcat.org lyrics: WHAT WAS YOUR NAME IN THE STATES
  7. ↑ The Unhymnal - Unofficial songbook of the Clemson University bands, edit circa 1967, Clemson University, Clemson, South Carolina.


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