Timeline for What "designs" the dihedral angle in modern airliners?
Current License: CC BY-SA 4.0
14 events
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| Feb 24, 2022 at 17:59 | comment | added | Robert DiGiovanni | @quietflyer well, almost nixed my stability graphs for that thought! Probably a combination of speed and dihedral effect from swept leading edge. Really a great observation (from experience). Would that suggest hang glider turns are slips? | |
| Feb 24, 2022 at 15:13 | comment | added | quiet flyer | (Could be a new ASE question, I have a theory as to what the answer is but do not know for certain.) | |
| Feb 24, 2022 at 15:13 | comment | added | quiet flyer | You said "better for hang gliders"-- here's a mind-bender (which is probably best discussed in a chat room, I may delete this comment after a bit)-- when a hang glider is flying at high speed (low angle-of-attack) (control bar well pulled in) it shows strong spiral stability or roll stability (i.e. pilot must maintain a significant roll input toward inside of turn to prevent bank angle from decreasing)-- this is not the case at low speed (high angle-of-attack). Yet we know that the dihedral-like effect of sweep is most pronounced at high angle-of-attack. What on earth is going on here? | |
| Feb 24, 2022 at 14:14 | history | edited | Robert DiGiovanni | CC BY-SA 4.0 |
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| Feb 23, 2022 at 15:43 | history | edited | Robert DiGiovanni | CC BY-SA 4.0 |
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| Feb 23, 2022 at 15:38 | comment | added | Robert DiGiovanni | @quietflyer it seems you are questioning the need for dihedral at all, and this is a very valid design thought. My point is (we already have yaw dampers) why not have (safely) automated roll dampers on the wings, like birds | |
| Feb 23, 2022 at 15:36 | comment | added | Robert DiGiovanni | @quietflyer interestingly enough, when the gust passes the plane has absorbed some of its energy, rolling away and moving downwind. Now, it is slipping in the direction where dihedral helps it. Also (do the math), a rolled dihedral also produces less vertical lift, so the plane also sinks. | |
| Feb 23, 2022 at 14:56 | comment | added | quiet flyer | But, that's just the reaction to a gust. Doesn't mean that dihedral isn't generally stabilizing overall. And like you note, sideslip plays a critical role. (And note that the average condition of the atmosphere obviously can't be a steadily increasing gust from one direction!) | |
| Feb 23, 2022 at 14:53 | comment | added | quiet flyer | (Actually, didn't you say as much in your own answer here? aviation.stackexchange.com/questions/80882/… ) | |
| Feb 23, 2022 at 14:52 | comment | added | quiet flyer | Re "The roll from a crosswind gust applies force from drag, whereas the vertical lift differential and slip effectively counteract it with straight wings."-- are you saying that if aircraft with dihedral is struck with crosswind gust from left, the dihedral will help to prevent the aircraft from rolling to the right? If so, the truth or fallacy of that assertion could make a new ASE question. (I would say, "false". The crosswind gust interacts w/ dihedral to create an unwanted difference lift between the two wings.) | |
| Feb 23, 2022 at 14:29 | history | edited | Robert DiGiovanni | CC BY-SA 4.0 |
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| Feb 22, 2022 at 13:44 | history | edited | Robert DiGiovanni | CC BY-SA 4.0 |
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| Feb 22, 2022 at 13:08 | history | edited | Robert DiGiovanni | CC BY-SA 4.0 |
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| Feb 22, 2022 at 13:03 | history | answered | Robert DiGiovanni | CC BY-SA 4.0 |