Advantage of all flying tailplane?

[max nodifference]

Just wondering what the benefits of an all flying tailplane versus a horizontal stab?

[Oz_Pilot]

Reduced trim drag is a good start: can set (read: trim) the AoA of the tailplane to give required downforce, then fair the elevators to reduce drag.

[gaunty]

Except when it is on a Piper or Nomad

[Flight Safety]

If memory serves, the all flying tailplane was first used on the Bell X-1 when it was found that pitch stability could be maintained during the transition from sub to supersonic flight, caused by the massive center of lift change already mentioned. I also seem to remember that there's a blanketing effect of the tail surfaces during transonic flight that the all flying tailplane also overcomes. The major effect of the all flying tailplane is the ability to exert massive control forces in the pitch axis when its required.

I also understand that this "technology" was found to be a requirement for supersonic flight in fighters, and consequently the USAF kept this a secret for 5 years or so from the Soviets after this discovery. I understand that's why the F-86 has an all flying tail, while the Mig-15 has a regular horizontal stab with elevators. Nearly all supersonic aircraft today have all flying tailplanes (the Concorde being a notable exception), while subsonic aircraft don't really require it and use the horizantal stab for trim purposes instead. Some naval designs however use the all flying tailplane even in subsonic aircraft where the ability to exert massive control force in pitch is needed for flight safety in operations like carrier landings. The A-7 Corsair comes to mind as an example of this.

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Safe flying to you...

[This message has been edited by Flight Safety (edited 21 February 2001).]