Timeline for Influence of propeller blade shape and tip shape on its behaviour?
Current License: CC BY-SA 4.0
9 events
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| Sep 24, 2021 at 13:13 | comment | added | Sixtyfive | Awesome, thank you Robin, that was the last part of it that made me scratch my head. Hoping your answer will get some more upvotes! | |
| Sep 24, 2021 at 13:12 | vote | accept | Sixtyfive | ||
| Sep 24, 2021 at 12:28 | history | edited | Robin Bennett | CC BY-SA 4.0 |
Added a note about under-camber.
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| Sep 24, 2021 at 12:19 | comment | added | Robin Bennett | 'undercamber' refers to the cross section, specifically on the side of the prop that faces backwards (or the bottom, when the prop is sitting on a table, as in the photos). If the prop was a wing, it would be the lower surface. 'Undercambered' means the same as 'concave', but specifically for the lower surface or an aerofoil. It requires slightly more advanced manufacturing than a flat bottomed aerofoil, if you're carving it from wood. Undercamber doesn't really do anything specific, it's just something that happens when an aerofoil has a lot of camber and is also thin. | |
| Sep 24, 2021 at 10:31 | comment | added | Sixtyfive | Okay, so it's only about what you said with regard to "making more of the prop not its tip". Then perhaps the purpose of the undercamberedness (as I understand it, the "negative bulge" on the back side of the prop, but not a native speaker of English!) is to have increase the lift of the prop's airfoil, so to speak ... more air moved for each rotation? | |
| Sep 24, 2021 at 10:23 | comment | added | Robin Bennett | I was talking about the wide chord at about half span. It's not related to the aerofoil. I think part of the odd shape is that this extra width is mostly achieved by extending the trailing edge (compare with an APC 'slow fly' prop) but I think that is to keep the thickest part fairly straight. | |
| Sep 24, 2021 at 10:20 | history | edited | Robin Bennett | CC BY-SA 4.0 |
added 32 characters in body
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| Sep 24, 2021 at 10:16 | comment | added | Sixtyfive | Wow, thank you for addressing all the points! One question though: what you call "bulge" is the top-part of what the manufacturers call "undercambered", i.e. both refer to the same airfoil shape as it would appear in a cross-section? Or are "bulge" on the top and "undercamberedness" at the bottom features that need to be talked about separately? | |
| Sep 24, 2021 at 10:09 | history | answered | Robin Bennett | CC BY-SA 4.0 |