Any thoughts on why the delta wings are naturally more stable in pitch, so they don't require any tail surface? What's the physics behind this?

  • 2
    $\begingroup$ "What's the physics behind this problem?" Problem? Why is this a problem? $\endgroup$
    – MichaelK
    Sep 28 '18 at 16:32
  • $\begingroup$ Never seen a Flying Plank? Rectangular wing with a vertical tail and cockpit pod. Very stable in pitch. Neither taper nor sweep. $\endgroup$
    – Zeiss Ikon
    Sep 28 '18 at 17:15
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    $\begingroup$ @ZeissIkon whether or not Darjan has seen a Flying Plank, the issue remains as unclear as before your comment. He's asking about the physics and what makes it inherently stable, not what delta planes exhibit such characteristics. $\endgroup$
    – Jihyun
    Sep 28 '18 at 23:39

This is a very good question, as it shows some of the misunderstandings regarding "tailless" aircraft. With deltas, one can consider them as blended wing/tails.

The function of a horizontal tail surface is pitch control. The back of a delta is certainly large enough to do this. So much so, that now one can design a forward canard to go with it. This plane should pass the horizontal drop test (nose must go down).

Notice that birds, wanting more straight wing lift, "unblend" a little and also have a fan tail. Delta's do not generate as much lift as a comparable straight wing.

So designers can work with what they need, particularly with desired speed range. Faster, the wings can pull in a little, as with the FB-111 swing wing.


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