So I am designing a biplane,I know the weight.I want to know what is the lift formula , volume ratio and aspect ratio for a biplane? I know the formulas for monoplane


closed as unclear what you're asking by Dan Hulme, Ralph J, fooot, SMS von der Tann, David Richerby Sep 2 '18 at 21:38

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ What calculations in particular are you asking about? Are you trying to design a biplane, or to measure the wing and tail area of an existing one? Please edit your question with more details. $\endgroup$ – Dan Hulme Sep 2 '18 at 9:31
  • $\begingroup$ Yes sir,I am designing a new biplane. I want to know how is the lift formula, volume ratio and aspect ratio different from the conventional one....so I know the weight of my plane ,I have to calculate the wing dimensions and tail dimensions...I know the method for conventional plane. . $\endgroup$ – sai teja Sep 2 '18 at 11:59
  • $\begingroup$ You need to do a few research on the internet,there are articles on google that'll help you understand these basics....Lift formula,aspect ratio,reynolds number etc.....mostly on the net,just do your research.Goodluck man.@sai teja $\endgroup$ – David Teahay Sep 2 '18 at 17:53
  • $\begingroup$ So I have actually gone through the basics. So the thing is in the net I wasn't able to find any calculations for biplane,so I thought stack exchange was the place ! $\endgroup$ – sai teja Sep 2 '18 at 18:08
  • $\begingroup$ Hi Sai, welcome to aviation.SE. Unfortunately I feel that despite your edits your question is not really answerable as it is now. It would either require an overly long answer, or assume that you know things that you might not know. It would be better if you could focus on a specific point (for example, "given wing load factor, MTOW, and top speed, what is the formula to dimension the main wing of a biplane?") and ask other specific questions separately, this will help both you and us. You can also look here for guidance on how to ask: aviation.stackexchange.com/help/how-to-ask $\endgroup$ – Federico Sep 4 '18 at 8:03

They are the same, but you have to use the total area of both wings multiplied by an interference factor that will be $<1$ to represent the loss of efficiency due to interference between both wing planes.

  • $\begingroup$ Oh ok thank you sir!...how do I get the interference factor.. also I have edited my question.so I want to know from the design point of view how is it different from a monoplane $\endgroup$ – sai teja Sep 2 '18 at 12:04
  • $\begingroup$ There is a wealth of information from existing designs. Generally, the horizontal stabilizer needs to be large enough to counteract the nose up pitching tendency of the wing at higher angles of attack. Also it should be of a lower aspect ratio so the wing stalls first. Building models and flying them is hugely helpful in gaining expertise in design. Interference between wings can be improved by putting one ahead of the other, and by increasing space between them. $\endgroup$ – Robert DiGiovanni Sep 30 '18 at 9:08

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