A plane question?

[Sue Durnim]

As a matter of interest, I have a question for all aircraft and physics experts, take a typical Jumbo Jet or similar plane with a typical amount of passengers, normal fuel on board, on a typical journey, say America, my query is :

 

At what speed does a plane have to fly

before it plummets out of the sky?

[Dizzy]

Oooh I'd rather not think about that thanks

 

Guess the speed would depend on the aerodynamics of the plane in question and maybe the surrounding air pressure too etc

 

I really have no idea though.

 

Another thought... what happens if a plane flies too fast

[Evil Sid]

160 mph

[Sue Durnim]

Evil Sid, is 160 mph, a guess?

[LymmParent]

There's a stall speed for every aircraft, at which point it will fall out of the sky, but the calculations are complicated and things like angle of flight come into it. Somewhere in the pilots' handbook for jumbos there must be a general guideline, but they don't tend to tell passengers things like that.....

[asperity]

Apparently it depends on the weight of the plane (i.e. is it loaded or empty) and the disposition of the flaps. One site I looked at gave 85 knots for an unladen 747-400.

[Sue Durnim]

Thanks LymmParent, it's just a question that's baffled me for a while,

sounds like there is no obvious answer.

[observer]

Lift is provided by the movement of air flow over and under the wings; at slower speeds (EG when landing) a slower speed is achieved by exagerating the bow in the wing by use of the flaps. At normal flight speeds, use of the flaps would create additional drag, thus slowing the aircraft down.