AboutPaul Soderman Expertise Aeronautics, Fluid Mechanics, Aeroacoustics, Noise Control, Muffler Design, Wind Tunnel Research.... I know nothing about India - do not ask about schools, jobs, application requirements, career choices, etc. for India. Please, no text message verbiage; I prefer full words in full sentences. Thanks.
Experience 37+ years with NASA as Aeronautical Engineer in research lab (retired). Specialty in aerodynamics, aeroacoustics and wind tunnel research. Publications 95+ technical papers and book chapters. Education/Credentials: BS/MS Aero Engineering - U. of Washington. Graduate studies - Stanford U. Awards and Honors AIAA Associate Fellow (American Institute of Aeronautics and Astronautics
Expert: Paul Soderman Date: 6/10/2008 Subject: wings
Question hello and thanks Paul. Ive been struggling with the math for lift for wings. Id like to build something like a dirigible motorglider using helium. Are there any simple guidlines for wing aspect ratio vs the weight of the craft?
Am I even going about this the right way? Thanks again.
tanner
Answer Hi Tanner
I'm curious about the design of your aircraft because conventional dirigibles don't depend on wing lift, but I assume you have something different in mind. Wing lift, L, can be calculated as follows:
L = Cl q S
where Cl = integrated wing lift coefficient, a dimensionless number that depends on wing shape and angle of attack
q = dynamic pressure = rho * V^2 / 2
rho = air density
V = flight speed
S = wing area
Of course all units have to be consistent. In cruise, the lift must equal aircraft weight for level flight. (I am not counting lift due to helium of course.)
Aspect ratio does not enter directly into lift as long as the span is long compared to the chord. Aspect ratio does enter into induced drag (drag due to lift) - high aspect ratio wings create less drag than low aspect ratio wings.
If you tell me more about your design and mission, I might be able to calculate some numbers for you.
Paul
