rtfm
Well-Known Member
Hi guys,
Yes, I know I should wait for my aircraft design books to arrive, when All Will Be Revealed, but I can't wait. So here is a quick outline of my approach, a statement of my confusion, and a plea for help...
I have a copy of Profili. Two copies, actually - an older version and the current version. Using this software I make a decision such as: I want to cruise at 120kts. I then select an airfoil, generate drag polars, and using the provided L/D tangent line, determine that the best L/D ratio occurs at (say) 4 deg AoA.
Armed with this information, I then run the virtual wind tunnel and transfer the results to the Wing Crafter.
Here, I set a number of wing sizes and check what the total lift is at 120kts, zeroing in on the wing size which provides the MAUW amount of lift at 120kts.
So much for S&L flight. Now on to takeoff and landing:
Working on the principle that since my project will employ a freewing design, and because of this, I'll be able to increase the AoA of the entire wing at takeoff and landing, I calculate this wing's lift at 12 degrees AoA.
And now for the problem:
The amount of lift generated by this wing at max AoA is way less than I'd expect. My takeoff speed is going to be way too high.
What have I done wrong?
Regards,
Duncan
Yes, I know I should wait for my aircraft design books to arrive, when All Will Be Revealed, but I can't wait. So here is a quick outline of my approach, a statement of my confusion, and a plea for help...
I have a copy of Profili. Two copies, actually - an older version and the current version. Using this software I make a decision such as: I want to cruise at 120kts. I then select an airfoil, generate drag polars, and using the provided L/D tangent line, determine that the best L/D ratio occurs at (say) 4 deg AoA.
Armed with this information, I then run the virtual wind tunnel and transfer the results to the Wing Crafter.
Here, I set a number of wing sizes and check what the total lift is at 120kts, zeroing in on the wing size which provides the MAUW amount of lift at 120kts.
So much for S&L flight. Now on to takeoff and landing:
Working on the principle that since my project will employ a freewing design, and because of this, I'll be able to increase the AoA of the entire wing at takeoff and landing, I calculate this wing's lift at 12 degrees AoA.
And now for the problem:
The amount of lift generated by this wing at max AoA is way less than I'd expect. My takeoff speed is going to be way too high.
What have I done wrong?
Regards,
Duncan
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