Aerowerx
Well-Known Member
I have been studying R&M #2935. It appears to answer all of my questions regarding how to calculate span loading of a wing, AKA lift distribution.
The math seems pretty easy, at least for me, but not being an aero engineer there are a few things that are not clear to me, and I am still trying to put the pieces in order.
For example, on page 25 just below equation 62 for lambda (interpolation function), it says that parameter y (span wise dimension) is "measured in terms of the wing chord". Just what does that mean? Divide by the local chord? Root chord? Tip Chord? Mean chord?:ermm:
Then on page 31, just above equation 92 it says that lambda is +1 at the center of the wing and -1 at the tips (and 0 somewhere inbetween). I don't get that at all. I tried playing around with equation 62, which defines lambda and get nothing at all like this. Equation 62 is plotted in Figure 23, and it has values from 1.0 at the center to approaching 0.0 at the tips, similar to what I am getting. What am I missing here?
[Edit] The way I mathimaticaly interpret Equation 62 is that, no matter how you interpret parameter 'y', lambda will be +1.0 at the center of the wing and approaching 0.0 at the tips (=0.0 with an infinite span)
Are there any better papers than this one? Yes, I have seen the various spreadsheets, but I want to understand the math involved. Besides, I have not seen anything that clearly says "this calculates a sine-cubed bell shaped distribution".
Better stop now and get to bed before I start embarrasing myself. It is 1:30 am now (work 2nd shift) and I am tired and can't think any more.
Jim
The math seems pretty easy, at least for me, but not being an aero engineer there are a few things that are not clear to me, and I am still trying to put the pieces in order.
For example, on page 25 just below equation 62 for lambda (interpolation function), it says that parameter y (span wise dimension) is "measured in terms of the wing chord". Just what does that mean? Divide by the local chord? Root chord? Tip Chord? Mean chord?:ermm:
Then on page 31, just above equation 92 it says that lambda is +1 at the center of the wing and -1 at the tips (and 0 somewhere inbetween). I don't get that at all. I tried playing around with equation 62, which defines lambda and get nothing at all like this. Equation 62 is plotted in Figure 23, and it has values from 1.0 at the center to approaching 0.0 at the tips, similar to what I am getting. What am I missing here?
[Edit] The way I mathimaticaly interpret Equation 62 is that, no matter how you interpret parameter 'y', lambda will be +1.0 at the center of the wing and approaching 0.0 at the tips (=0.0 with an infinite span)
Are there any better papers than this one? Yes, I have seen the various spreadsheets, but I want to understand the math involved. Besides, I have not seen anything that clearly says "this calculates a sine-cubed bell shaped distribution".
Better stop now and get to bed before I start embarrasing myself. It is 1:30 am now (work 2nd shift) and I am tired and can't think any more.
Jim
Last edited:
