Aerowerx
Well-Known Member
In the book "Tailless Aircraft in Theory and Practice", it says that Equation 6.3.8 describes the Horten bell shape lift distribution. Then on the same page (in my copy) is Figure 6.3.4 that shows the resulting curve.
I created a new spreadsheet that uses Equation 6.3.8 to calculate the twist. Just now got it working, and plugged the twist numbers into XFLR5. It turns out that it is NOT a sine^3 (cubed) distribution, but closer to a plain sine curve. The text in the book says that this eliminates adverse yaw and, in fact, creates proverse yaw. From what I have been reading I thought that you needed at least sine^2.5, and preferably sine^3 to create proverse yaw.
There is another equation, 6.3.6, that does give something that looks more like a sine^3, except that the region near the wing tips produces negative lift. The text says that it has vanishing adverse yaw. The problem with this equation, according to the text, is that it produces a lot more induced drag.
Can anyone clarify this?
I created a new spreadsheet that uses Equation 6.3.8 to calculate the twist. Just now got it working, and plugged the twist numbers into XFLR5. It turns out that it is NOT a sine^3 (cubed) distribution, but closer to a plain sine curve. The text in the book says that this eliminates adverse yaw and, in fact, creates proverse yaw. From what I have been reading I thought that you needed at least sine^2.5, and preferably sine^3 to create proverse yaw.
There is another equation, 6.3.6, that does give something that looks more like a sine^3, except that the region near the wing tips produces negative lift. The text says that it has vanishing adverse yaw. The problem with this equation, according to the text, is that it produces a lot more induced drag.
Can anyone clarify this?