Why can't an aircraft maneuver like a bird?

[horseguards]

In simple terms (if possible), why is an aircraft unable to achieve the manoeuvrability of a bird, eg, immediate stop, rapid acceleration, sudden change of direction? I'm guessing it relates to necessary strength and rigidity of the plane's structure, engine power/weight ratio.

 

[Pkruse]

This should be an interesting discussion. I look forward to following it.

But one thing to consider is that with airplanes, the speeds are much higher. That means that sudden changes in direction or speed are seriously limited by physical considerations of F=ma. Some aircraft will routinely see more acceleration than any bird can survive, so one may argue from that perspective that they are more maneuverable than birds.

 

[rcgldr]

Most aerobatic radio control helicopters can outmaneuver birds, due to relatively high thrust to weight ratios. Example video:

 

[russ_watters]

Fixed wing aircraft only travel and thrust forward, with limited ability to alter that. Birds can do different things due to the fact that it is wing flapping causing the lift and thrust.

 

[someGorilla]

The main reason is sheer size. (And the second reason is: passenger comfort )
Wing-flapping becomes very inefficient when wing area gets large. Think how much air resistance you have if you try to flap very large wings. It's the same for natural or human-made flyers: wings flapping is very good for small sizes like the hummingbird - and see this http://www.youtube.com/watch?v=Cov7-XWUa18 - while condors and albatrosses are good at gliding but not at aerobatics.

 

[CWatters]

In simple terms (if possible), why is an aircraft unable to achieve the manoeuvrability of a bird, eg, immediate stop..

Birds have had a lot longer to figure out how to do it? We've only had about 100 years and already a small model plane or helicopter can out manouver a bird.

Birds rarely do aerobatics. Many times birds have formed up on model glider and will happily follow them around the sky... until the model pulls a loop.

 

[A.T.]

Birds rarely do aerobatics.

An neither it is a top priority for most planes. Birds developed what they need, and aircraft designers design what is most useful for humans.

 

[AJ Bentley]

Simple answer : mass : inertia.

Mass scales as volume which is a cubic on the size.

A small model aeroplane is every bit as manoeuvrable as a bird and more.

 

[Vadar2012]

You are pretty much right. Different aircraft are designed for diffrent things. Rotary winged aircraft are designed for maneuvability and fixed are designed for speed and range. For example, typical ranges are 1200 kms to 2400 km respectively, with the obivous differences in maximum speed.

In terms of fixed wing, due to the speed the aircraft is limited by the materials strength. When you reach these speeds you start to create shock waves on the wings, which if you turn sharp enough can create one stong enough to cut the wing off. Interestingly, this can occur even before reaching the speed of sound, as turning can increase the speed of the flow over the wing to the required level. This is the main reason for fast aircraft having swept wings, to reduce the onset of this affect. Whereas, aircraft that need to achieve distance have straight wings.