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B-1B Lancer elevator activated individually

control axes

This B-1B Lancer's picture I captured from this Youtube video. The control axes is from Wikipedia.

As we know, the three "conventional" axes are as follows:

  • Roll axis controlled by aileron,
  • Pitch axis controlled by elevators (both at the same time),
  • Yaw axis controlled by rudder.

Then my questions are:

  • What is exactly that purpose (the single elevator activation), and
  • How it work? Is there new axis of it?
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That would be the correct control response for a combined roll to the right and nose up pitch command from the pilot. It looks like that photograph was taken while the pilot was in the middle of doing a check of their control services prior to taxi.

You can see similar results in the tower buzz sequence out of Top Gun. The final bit shows an F-14 from the tail which rolls to the right and pitches nose up with a similar control response from a combination of the tailplane and starboard wing spoilers.

enter image description here

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  • $\begingroup$ For completeness, that surface in question is a stabilator, not an elevator. $\endgroup$ – ymb1 Sep 5 at 12:03
  • $\begingroup$ Is it more efficient to use differential elevator deflection for roll (in addition to the normal use of elevators and ailerons) than to use the elevators only for pitch and the ailerons only for roll? $\endgroup$ – Terran Swett Sep 5 at 12:04
  • $\begingroup$ @Tanner Swett It depends on the speed and flight profile. Ailerons offer good roll authority in Low subsonic flight while differential spoilers and all moving tailplane work better in high subsonic and supersonic flight regimes. I’d say differential spoilers offer the best roll authority but combinations of control surfaces are frequently used to increase maneuverability and maximize control authority. $\endgroup$ – Carlo Felicione Sep 5 at 13:00
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    $\begingroup$ @ymb1 I prefer the term all moving tailplane in these kinds of applications because it offers both control in roll and pitch. Stabilator is also common but there is a considerable difference in operation between a PA-28 or C-177 stabilator and that found on say an F-16. $\endgroup$ – Carlo Felicione Sep 5 at 13:04
  • $\begingroup$ @Tanner - ailerons have move leverage than elevons, but fighters generally have fairly short wings so the difference is small, and the designers wanted to use the whole trailing edge of the wing for flaps. $\endgroup$ – Robin Bennett Sep 5 at 13:57

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