Lets talk about maneuvering speed

[denverpilot]

To be accurate, your example would have to reference underwater currents on a submarine or something else submerged, not wave action on the surface. The point is, gust forces will be reduced to a resultant vector acting upon the wing structure. That vector can shift, but when considering wing loading and structural limits the vertical component is what will significantly impact the aircraft. Any other direction will not increase lift significantly, which in turn will not increase load factor significantly.



Edit: I get what CBS is saying, and the difference is theoretical/practical. The bigger issue though, would be asymmetric wing loading. Maneuvering speed is built off of symmetric when loading, whereas turbulence penetration speed should consider asymmetric forces.

Asymmetric forces acting on different parts of the aircraft at the same time is all I was getting at. The analogy is weak, agreed. But aircraft aren't (usually) ripped apart by single one direction forces.

 

[Cooter]

No, he has a valid point. However, you cannot design for every eventuality and you do want to fly at a speed that will get you through the turbulence expeditiously without stalling the wing at every vertical gust.

I concede he has a valid point, theoretically. I wanted to better understand what he was saying. In considering gust factors, horizontal component is negligible. Design considers what is likely to be encountered, not what is theoretically possible to encounter. If the point is that an aircraft is not absolutely protected from gust factors at maneuvering speed, I agree. That is why there is a turbulent air penetration speed. But, the most significant factor would not likely be the horizontal component of a gust, it would be the asymmetric force applied for the airframe. Asymmetric limits are significantly lower than symmetric limits, and will result in an airspeed slower than Va.
Practically, a gust isn't "likely" to raise airspeed and impart vertical velocity sufficient to over stress the aircraft at maneuver speed.

 

[coloradobluesky]

If you want to understand it you need to look at videos of model airplanes in wind tunnels and watch what happens. They put smoke in the wind tunnels.

Mathmatically, its really complicated. Just read the course descriptions on some graduate courses in Aeronautical Engineering Univ of Colo course catalog. Yike! Prerequistite 20 hours of advanced calculus and diff eq and probability theory and linear systems with a bunch of hard mathmatical computer programming. You have to be a genius to take all that stuff and understand it.

 

[denverpilot]

Mathmatically, its really complicated. Just read the course descriptions on some graduate courses in Aeronautical Engineering Univ of Colo course catalog. Yike! Prerequistite 20 hours of advanced calculus and diff eq and probability theory and linear systems with a bunch of hard mathmatical computer programming. You have to be a genius to take all that stuff and understand it.

Fluid dynamics physics math is a *****. The worst grade I've ever gotten in a class but it still taught me a ton. Also gives me an irrational and completely emotional but reasonable hatred of calculus. Ha.

 

[alfadog]

Fluid dynamics physics math is a *****. The worst grade I've ever gotten in a class but it still taught me a ton. Also gives me an irrational and completely emotional but reasonable hatred of calculus. Ha.

I enjoy basic calculus, started taking it in high school. More advanced math like linear equations and the like, I just learned them to get through them. Basic calculus is useful and gives you an understanding of and feel for everyday physical phenomena that have a mathematical basis, i.e. all of them, LOL. I'm not so sure if that is true of the more advanced maths.

 

[Cooter]

Fortunately, many of the aerodynamic concepts are reducible to very understandable math for those of us who are mathematically challenged.

 

[WarrenG]

I've been reading this forum for the last week or so and learning a ton. I'm just starting my PPL and have been studying quite a bit. I had to chime in on this topic. So here's my brand new 2 cents...

My understanding is that VA occurs at the point where stall speed intersects the Positive Limit Load Factor (amount of "weight" loaded on the wings while in a turn, upward gust, etc. before damage occurs). Since stall speed increases with the amount of force ("weight") placed on the wings, you will typically stall before you pull enough G's to cause any damage. However, if you are flying faster than VA, you are able to pull more G's than the Limit Load Factor before the plane will stall and thus damage can now occur.

So basically if you fly under VA your wing will stall before anything breaks while maneuvering. But now my questing is this.... Will the wing stall and prevent damage from an upward gust of air while flying straight and level?

 

[Cooter]

I've been reading this forum for the last week or so and learning a ton. I'm just starting my PPL and have been studying quite a bit. I had to chime in on this topic. So here's my brand new 2 cents...

My understanding is that VA occurs at the point where stall speed intersects the Positive Limit Load Factor (amount of "weight" loaded on the wings while in a turn, upward gust, etc. before damage occurs). Since stall speed increases with the amount of force ("weight") placed on the wings, you will typically stall before you pull enough G's to cause any damage. However, if you are flying faster than VA, you are able to pull more G's than the Limit Load Factor before the plane will stall and thus damage can now occur.

So basically if you fly under VA your wing will stall before anything breaks while maneuvering. But now my questing is this.... Will the wing stall and prevent damage from an upward gust of air while flying straight and level?

It should, assuming no asymmetric forces. A vertical gust encountered by the aircraft will essentially hit that gust at an angle since it is moving into and through it. The relative wind will not be parallel to the aircraft flight path but will shift down. So, the effect will be that AOA increases beyond the critical angle of attack before maximum wing loading is encountered. Structural design considers the maximum vertical gust that is likely to be encountered.