# Search results

Thank you.
2. ### Move to Xenforo

There should be a way to object to certain ads. I am really tired of seeing a women's a in every ad while reading a thread.
3. ### BBC report on HPA Icarus Cup competition 2019

Thank you for posting this. When I was in college I was on a senior design project to design a man powered airplane. It looks like students are still having fun with this! Doug
4. ### Move along - nothing to see here

I look forward to the progress of your project. If you do not provide basic dimensions and performance targets, how can we judge what you are doing is reasonable? Doug
5. ### NACA 6-series cusp

This points up the weakness and strength of these empirical methods. They only do a fair job of predicting actual numbers. Their strength is comparing similar airfoils. So if you have a good set of data on an airfoil similar to the one you want some numbers for, you can estimate the numbers of...
6. ### NACA 6-series cusp

Thanks for airfoil coordinate plot. If you are interested in other NACA 6A series airfoil coordinates here is a link http://pdas.com/sections6a.html The PDAS.com website has a lot of cool programs.
7. ### NACA 6-series cusp

Show us a picture please. If you want to, please tell us the U/L performance characteristics you used for the design of the airfoil. Doug
8. ### NACA 6-series cusp

Actually not quite the same. NACA added the camber to the symmetric airfoil perpendicular to the camber line. Riblett just added the camber to the y coordinate of the symmetric section. So Riblett's airfoils have somewhat more camber than the equivalent NACA sections. Doug
9. ### NACA 6-series cusp

Riblett did publish cusp as well as non-cusp airfoils (GA Airfoils book). The cusp is the effect of aft loading of the airfoil. Aft loading gives higher lift coefficients, but with higher negative pitching moments. The NACA airfoils (Theory of Wing Sections book) provide a great set of airfoils...
10. ### Low Speed Airfoil Design Paper

Thanks for posting this reference, it looks like it has a lot of interesting info. Doug
11. ### A complete report on the aerodynamic and strength design of an ul aircraft

Hi Christos, Thanks for all the information. I hope you will also share with us the minimum predicted drag coefficient of your airplane. Thanks again, Doug.
12. ### A complete report on the aerodynamic and strength design of an ul aircraft

Hi Cristos, What is your strategy for the boundary layer control? Are you planning on vacuuming off all the boundary layer? Doug
13. ### A complete report on the aerodynamic and strength design of an ul aircraft

I had a close look at the lift vs drag curve. The base airfoil you are using looks pretty good with a Cd,min of about .003. What airfoil are you using?
14. ### A complete report on the aerodynamic and strength design of an ul aircraft

Hi Christos, What boundary layer control method are you using, sorry if I missed it in your posts. And, have you validated your CFD method for the boundary layer control method you are using?
15. ### A complete report on the aerodynamic and strength design of an ul aircraft

Hi Christos, What I was interested in for specs: design lift coefficient and Reynolds number at cruise, climb; design thickness, zero lift pitching moment. If you have a plot of the lift vs drag at the cruise Reynolds number that would be good too. Thanks!, Doug
16. ### A complete report on the aerodynamic and strength design of an ul aircraft

Could you share the design specifications (Reynolds number, Cl, …) and performance characteristics of your airfoil? Thanks, Doug
17. ### Drag and prop efficiency real-world examples?

Hi cluttenfred, What Reynolds number are you running the ARA airfoil? I tried 1,000,000 and got a Clmax of about 1.1 using the Eppler code. Doug
18. ### A complete report on the aerodynamic and strength design of an ul aircraft

Technology has progressed a lot in 20 years. Back then a coworker of mine got a 16 node (16 pc's connected in parallel) Linux cluster. He was able to do similar solutions to what you are doing. I was doing similar calculations on remote Linux clusters requesting 48 processors. Time marches on...
19. ### A complete report on the aerodynamic and strength design of an ul aircraft

Thanks for the info. My next question is what kind of a computer are you using to make the calculations and how long does it take?
20. ### A complete report on the aerodynamic and strength design of an ul aircraft

Hi christos, How many points are you using in your CFD grid and how many points do you use to resolve the boundary layer? Thanks for sharing your results. Doug