Timeline for Can yaw develop a spiral dive?
Current License: CC BY-SA 4.0
11 events
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| Jun 25, 2021 at 17:04 | comment | added | Robert DiGiovanni | @quietflyer you are correct that trying to generalize "high or low wing" is not the best way to describe it. More accurate is side area in relation to CG, which can be used to create an "anhedral or dihedral effect" which either prevents or couples a roll into a yaw input. Ironically, the more it rolls, to less it is skidding. Years ago an instructor showed me how to turn a R/C plane with rudder. Before that I just banked and yanked. It was a high wing trainer with a lot of dihedral, so I see what you are saying. | |
| Jun 25, 2021 at 15:07 | comment | added | quiet flyer | I'm also having trouble reconciling your suggestion that high-wing aircraft tend to roll out of turns, w/ your suggestion that low-wing aircraft tend to exhibit a stronger roll response to rudder inputs. In truth, enhanced roll stabilty and enhanced coupling between slip and roll are both consequences of "effective dihedral". "Effective dihedral" can be created by a high-wing geometry, or by sweep, as well as by actual dihedral. Anyway I can't agree w/ the suggestion that it is easier to use the rudder to control roll in low-wing planes than in high-wing planes. | |
| Jun 25, 2021 at 13:44 | comment | added | quiet flyer | I guess it all depends on what variables we hold constant. In the real world, for manned aircraft (as opposed to model airplanes), seems to me a spiral dive is normally only a hazard encountered when instrument flying, and I'm having a hard time imaging a scenario where a tendency to allow sideslip while turning would make a spiral dive more likely to develop. Because of the rolling-out torque that is normally created by a sideslip. But yes you are right, for a given turn rate, more bank is required if the plane is slipping than if it is not. On the other hand, for a given bank angle.. | |
| Jun 25, 2021 at 12:51 | comment | added | Robert DiGiovanni | @quiet flyer A turn at a given rate will have a steeper bank on the slip. Vertical CG (in relation to side area) does play a role in roll rate from rudder application (a dihedral "effect"). While coordinated is best, a spiral with wings unstalled would be "safer", than a skid induced tip stall, which can be sudden, especially low. The tip stall recovery technique for the DC3 involved reverse ailerons, which would not be good if the tip wasn't stalled. These thoughts made me very interested in slats. | |
| Jun 25, 2021 at 12:40 | comment | added | quiet flyer | But in general, skidding turns are considered an invitation to a stall-spin accident. Accidentally allowing some slip in a turn is generally not considered dangerous, though your answer is suggesting that it is an invitation to a spiral dive--?? | |
| Jun 25, 2021 at 12:38 | comment | added | quiet flyer | Your statements about the effects of high-wing or low-wing configurations don't seem accurate to me either. Oh well, the topics of slips and skids have proven fertile ground for many competing answers in the past as well-- | |
| Jun 25, 2021 at 12:29 | comment | added | quiet flyer | (Also, for a given bank angle, the wing's lift vector is larger when the plane is skidding than when it is coordinated, and larger when it is coordinated than when it is slipping. For a given turn rate at a given airspeed, on the other hand, the bank angle and the wing's lift vector are both least in the skidding turn and greatest in the slipping turn.) | |
| Jun 25, 2021 at 12:24 | comment | added | quiet flyer | Re "Slipping turns are much more prone to create a spiral dive because the critical ingredients are already there: loss of lift from the steeper bank and a stronger force pulling the plane sideways."-- I question this. Either a slipping turn or a skidding turn can be flown at any bank angle. In a slipping turn, dihedral will generate a roll torque towards wings-level, while in a skidding turn, dihedral will generate a roll torque away from wings-level. | |
| Jun 25, 2021 at 0:12 | history | edited | Robert DiGiovanni | CC BY-SA 4.0 |
Better answer
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| Jun 25, 2021 at 0:04 | history | edited | Robert DiGiovanni | CC BY-SA 4.0 |
grammer
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| Jun 24, 2021 at 23:26 | history | answered | Robert DiGiovanni | CC BY-SA 4.0 |