Recent content by Retiree

1. Airfoils

A lot of people flying high performance gliders would disagree with you.
2. Systems Reliability - Need Component Failure Probability Estimates

I am glad someone replied who knows something about statistical analysis. This a very complicated field.
3. EAA No Longer Has Free SolidWorks

I didn't see anything about intellectual property in the link. But it seems they go out of their way to keep your info secure...
4. "SkyWing" hybrid wing body ultralight

In general as the camber of an airfoil increases the negative pitching moment, nose down, increases. I assume bending the nose up, like reflexing the trailing edge up, would act to decrease the camber and decrease the negative pitching moment. But like a previous comment, it would be a good idea...
5. Airfoil Circumference and Area

Hi rtfm, Do you know how the weight is calculated in the program? Also, how are the areas calculated, planform or surface? Thanks, Doug
6. Airfoil Circumference and Area

This is the correct formula to calculate the approximate area under the airfoil coordinates, not the formula in the spreadsheet. The formula should be in column G.
7. Minimum drag just prior to flow separation?

Bob Liebeck already figured this out, 40 some years ago! https://en.wikipedia.org/wiki/Robert_H._Liebeck https://uofi150.news-gazette.com/people/bob-liebeck
8. Eppler Airfoils

As a point of information, why do you want to use an aerobatic airfoil for a horizontal or vertical tail?
9. Eppler Airfoils

You can't be sure that after you "tweak " it, the airfoil will have the same characteristics you want. It will not be an Eppler airfoil anymore. If you do tweak it, please don't post the airfoil coordinates as an Eppler airfoil. Doug
10. Eppler Airfoils

Eppler numbers his airfoils in series. So a type of airfoil might start at E600. Then the next airfoil in the series would be E601, he might be changing thickness or pitching moment. He wrote a book with all his airfoils, up to that point. He even put in the parameters he used for the designs...
11. MotoBird - 2 seat aircraft with Rotax 503

Looks really good especially if you get the same results with both meshes. Thanks again. Doug
12. MotoBird - 2 seat aircraft with Rotax 503

What airfoil section are you thinking about using for your project? How many points did you use in your CFD calculation, how many points did you try to get into the boundary layer? Thanks, Doug
13. The new project aircraft VP 12. Ukraine

Hi George, Your wing looks very thin. What is the thickness to chord ratio of the airfoil section? Thanks again. Doug
14. The new project aircraft VP 12. Ukraine

What airfoil section are using for the wing? Thanks. Doug
15. Suitable airfoil large thickness, high RE

Hi Berridos, Did you find a good airfoil? If so what is its characteristics? Doug