# Tag Info

Accepted

### Why force the nose of 737 Max down in the first place?

The main thing to avoid in aeroplane stability & control, is an aerodynamic nose up moment that is not commanded by the pilot. The uncommanded nose-up moment would not auto-stabilise, but rapidly ...
• 57.8k

### Why do most biplanes have their top wing slightly forward of the lower wing?

Placing the top wing ahead of the bottom wing in biplanes is called (positive) stagger. It is mostly used in small biplanes and improves pilot vision. In order to accommodate a variation of pilot ...
• 218k
Accepted

### Are helicopters aerodynamically stable?

It's complicated ;) There are two types of stability; dynamic and static. If an aircraft is disturbed by, say, a gust of wind, it will deviate from its attitude but then will immediately and without ...
• 30.8k

### Would a helicopter with the blades on the bottom fly the same, if at all?

Yes that is possible, like the Hiller flying platform demonstrated. It had two counter-rotating propellers inside a shroud and the pilot controlled his craft by shifting his body weight, like on a ...
• 57.8k
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### Why do aircraft need a vertical tailfin, but birds don't? (and lots of fish do?)

Not all of them need a fin: This is the Horten IV, a flying wing glider that did not need a fin (picture source). Instead, it used spoilers at the wingtips to create yawing moments, and the swept ...
• 218k
Accepted

### Why do blimps have fins?

What if the engines fail? In early airships this happened frequently, and many ships limped home on a reduced number of engines. Note that all airships were both vertically and laterally unstable. ...
• 218k

### What does it mean when an aircraft is statically stable but dynamically unstable?

Static stability means that a deviation from a trimmed state produces forces which return the system to this trimmed state. If these forces produce an overshoot which increases over time, such that ...
• 218k
Accepted

### What does it mean for a plane to be aerodynamically stable?

Static stability is the tendency of a system to return to its initial state after a disturbance. Typical disturbances in case of airplanes are: Flying into a vertical or horizontal gust A jerk on ...
• 218k

### Would a helicopter with the blades on the bottom fly the same, if at all?

We spend all our weekends mowing lawn with these guys. Courtesy: Helifreak.com You can find thousands of Youtube videos showing how comfortably they can do that
• 5,951
Accepted

### How does wing sweep increase aircraft stability?

Directional stability When a swept wing is flying in a sideslip, the windward side behaves like a wing with less effective sweep $\varphi_{eff}$ and the leeward side like one with more effective ...
• 218k

### Why force the nose of 737 Max down in the first place?

Counter-intuitively, lowering the nose of an aircraft is not done for the purpose of "going down". Climb/descent is managed with throttle, and speed is managed with the control column/stick. The logic ...
• 3,150
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• 218k

### Are there any fly-by-wire airliners with negative or near-neutral pitch stability?

No. Modern FBW airliners use less static stability than what the early jets were used to, but stability is still positive. The negative camber at the root airfoil of sweptback horizontal tails might ...
• 218k