Timeline for Why does a rectangular wing stall at the root first?
Current License: CC BY-SA 4.0
7 events
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| Aug 17, 2023 at 20:22 | comment | added | Rob McDonald | Another option is to play with a tool like OpenVSP / VSPAERO -- or XFLR5 or AVL or Tornado etc. These tools will show you the lift distribution for a given wing planform. You can make changes to the wing and see what it does to the lift and lift coefficient distribution. | |
| Aug 17, 2023 at 20:21 | comment | added | Rob McDonald | When you talk about a 3D wing, it can be difficult to define the stall AoA. Is it when the first sign of stall happens? Is it when you reach CLmax? The stall curve for a wing can be a sharp point, or it can be a gradual curve. For some wings, it reaches CLmax and pretty much stays there for a long way, not really coming back down. To figure out all the details, you need to get into quite a bit of 3D aerodynamic theory. Start with lifting line theory, move to VLM theory. It is complex and perhaps not worth your time when you can understand the end effect more readily. | |
| Aug 17, 2023 at 20:17 | comment | added | Rob McDonald | In another case (elliptical), the stall happens across the whole wing at the same time. Stall is more abrupt and has little warning. You lose roll control at the same time. In a third case (strong taper D or E), stall starts at the tip. It is somewhat gradual -- the inboard wing with lots of area keeps lifting. However, you lose roll control. In addition, if you're in a turn, one tip will stall first, causing a strong rolling moment where that wing will 'fall out' from under you. We can understand the implications of lift distribution on handling qualities without a lot of details. | |
| Aug 17, 2023 at 20:13 | comment | added | Rob McDonald | I don't think anybody said anything about increasing stall AoA. There might be some slight changes, but those get complicated. Lets pretend for a moment that part of the wing will start stalling at 10deg. In one case (rectangular wing) that happens inboard. Since it starts in one place and spreads, it will happen gradually -- the airplane will feel mushy. The tips will remain attached, which means the ailerons will be happy and roll control will be good. | |
| Aug 17, 2023 at 17:51 | comment | added | EquipmentOperator | Basically, how does this exchange in pressure across the top and bottom of the wing tips cause an increase in stall AOA? Would adding additional pressure to the top of the wing not exacerbate the adverse pressure gradient that causes the stall in the first place? | |
| Aug 17, 2023 at 17:49 | comment | added | EquipmentOperator | Excellent explanation for both the elliptical and rectangular wing and how they both must naturally achieve zero lift at the wing tip. It sounds like you are saying that the reduction of CL near the tips of the rectangular wing is aerodynamically caused by air pressure "bleeding over" from under the wing to the top of the wing. This sounds like a similar explanation to the excerpt from ANA I posted in the original question. So my secondary question is this: How does this all cause the stall to be delayed near the tips of the rectangular wing? Are the tips not at the same AOA as the root? | |
| Aug 17, 2023 at 3:27 | history | answered | Rob McDonald | CC BY-SA 4.0 |