1
$\begingroup$

Biplane wings interfere with each other, reducing the total lift often to about only 20% more than a mono wing of the same chord and span.

But at supersonic speeds - say, Mach 2, where Mach angle is 30 degrees, the wings (now provided with supersonic airfoils, before anyone asks) would have to be 0.5 chord-lengths apart for their shockwaves to interfere.

So, am I correct in saying that for a given chord-length separation, drag due to airfoil interference on vertically stacked multiplane wings interference decreases with Mach number?

Improve this question
$\endgroup$
1
$\begingroup$

Amazingly, at supersonic speeds it can work the other way. In the Busemann biplane the shock waves interfere in such a way as to actually reduce drag and also to reduce the sonic boom. Wide enough separation to avoid interference would actually increase supersonic drag.

See for example:

Improve this answer
$\endgroup$
7
  • $\begingroup$ Yeah I knw about that one. I like it, though I heard it had shockwave-swallowing problems that needed variable geometry. $\endgroup$ – Abdullah May 26 '20 at 7:55
  • 1
    $\begingroup$ @Abdullah Not sure why you are asking if you already know the answer. perhaps you could clarify your question to be more precise in what you do want to know. $\endgroup$ – Guy Inchbald May 26 '20 at 8:33
  • 1
    $\begingroup$ Well, I wasn't asking about a Busemann plane. More about 2 diamond airfoils stacked on top of one another. $\endgroup$ – Abdullah May 26 '20 at 9:38
  • 1
    $\begingroup$ Then I would suggest that yo edit your question accordingly. $\endgroup$ – Guy Inchbald May 26 '20 at 12:07
  • 3
    $\begingroup$ Busemann biplane - No shockwave, but no lift. Well, there's yer problem! $\endgroup$ – FreeMan May 26 '20 at 13:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.