Capt. Geoffrey Thorpe
Touchdown! Greaser!
- Joined
- Jun 7, 2008
- Messages
- 15,637
- Location
- DXO124009
- Display Name
Display name:
Light and Sporty Guy
In the past I have created some videos on the topic of lift and some of the nonsense that is taught to pilots – but those tended to be on the long side – sorry, once I get going, it’s hard to stop before I’ve tried to explain the origin of the universe. Anyhow, it was suggested that I make some shorter, more focused videos – OK, fine. First one is recorded, but not yet listed on YouTube.
What I would like, if you don’t mind, is watch it (below) and offer up comments / suggestions. I may consider re-recording. There are some things I am not happy about – the screen captures from the NACA video are pretty busy and the live markings don’t show up well for one. But then again, for a video that is going to earn 25 cents a month…
Tentative series plan (suggestions welcome about this also)
1: Fundamentals of how lift is generated. Intuitive, no math, not wrong.(below)
2: What about Bernoulli? The actual B’s equation, how it is useful, does not explain velocity differences top vs. bottom. Requires theory such as circulation to really work. This is where the wheels fall off popular explanations – example – if you apply the popular “venturi” theory, lowering flaps on final should cause an airplane to crash into the ground. Hard. Some of the “Bernoulli” demonstrations also have nothing to do with Bernoulli.
3: Airfoil shapes – Camber lines – lift vs drag. Thickness profiles – changes flow on both top and bottom. Compare camber lines, about 3 thickness values with Xfoil simulation. Other benefits of thickness somewhere in there.
4: “Venturi” theory – Real airfoils do not look like the cartoon airfoils. Venturi flow does not correlate to flow around real airfoil (as shown by FAA video pushing this theory – that cracks me up.) Predictions using this so called theory are totally wrong.
5: Circulation – should I tackle this? It’s a real theory. Whidden “Art and Science of Sails” does a nice job – I could crib some of that if I could find my book.
6ish: At some point I should be able to get into the wind tunnel here at school – I have fabricated a set of wing models – flat plate, thin cambered, a couple NACA foils with different thickness. Not sure of details, but I have time to sort it out – right now there is a grad student in there working on his thesis – that’s gonna take a while.
7: Dunno, might think of other things… open for suggestions.
What I would like, if you don’t mind, is watch it (below) and offer up comments / suggestions. I may consider re-recording. There are some things I am not happy about – the screen captures from the NACA video are pretty busy and the live markings don’t show up well for one. But then again, for a video that is going to earn 25 cents a month…
Tentative series plan (suggestions welcome about this also)
1: Fundamentals of how lift is generated. Intuitive, no math, not wrong.(below)
2: What about Bernoulli? The actual B’s equation, how it is useful, does not explain velocity differences top vs. bottom. Requires theory such as circulation to really work. This is where the wheels fall off popular explanations – example – if you apply the popular “venturi” theory, lowering flaps on final should cause an airplane to crash into the ground. Hard. Some of the “Bernoulli” demonstrations also have nothing to do with Bernoulli.
3: Airfoil shapes – Camber lines – lift vs drag. Thickness profiles – changes flow on both top and bottom. Compare camber lines, about 3 thickness values with Xfoil simulation. Other benefits of thickness somewhere in there.
4: “Venturi” theory – Real airfoils do not look like the cartoon airfoils. Venturi flow does not correlate to flow around real airfoil (as shown by FAA video pushing this theory – that cracks me up.) Predictions using this so called theory are totally wrong.
5: Circulation – should I tackle this? It’s a real theory. Whidden “Art and Science of Sails” does a nice job – I could crib some of that if I could find my book.
6ish: At some point I should be able to get into the wind tunnel here at school – I have fabricated a set of wing models – flat plate, thin cambered, a couple NACA foils with different thickness. Not sure of details, but I have time to sort it out – right now there is a grad student in there working on his thesis – that’s gonna take a while.
7: Dunno, might think of other things… open for suggestions.