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This is a webpage with lots of facts about bird flight including mainly wing shapes.

http://www.earthlife.net/birds/flight.html

Edweard Muybridge

Examples of birds in flight is evident in the early work of Edwaerd Muybridge who took photogrphs of birds at different stages in the flight cycle. These could then be used to interpret into key frames for an animation and drawn studies.

Don Bluth Drawing Birds in Flight

Here is a video of Don Bluth drawing out the different key frames of a brid in flight and explaining certain aspects, which will be very useful when studying birds and getting round to doin a simialr exercise myself.

"How to make birds fly good...

"Here is another webpage explaining, in depth, the details of a bird in flight including the actual movement of the wings during flight, like how it rotates, and how the bone structure creates certain movements.

http://www.brendanbody.co.uk/flight_tutorial/index.html
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This is an interesting comparison of the bone stucture of the arm of a human and the wing of a bird, and the similar bones that they have. This could help in understanding why and how the way a wing would move, being able to compare it to an arm.

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There is also a lot of inforamtion on the taking off as well as videos which will be very useful when analysing movements in more depth.

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This is a diagram from the book 'The Animator's Survival Kit' by Richard Williams, explaing the "technique for  making stiff, straight limbs look fluid" .

Bird Flight

Here is a lonk for a great website which has a lot of source material on bird flight including, photos, diagrams and videos of many different kinds of birds and in flight movements.

http://www.youtube.com/watch?v=6UlsArvbTeo&feature=player_embedded

How Wings Work...

This is just an example of the sort of material available on the website, making the aspects of bird flight much easier to understand.

How Ornithopers Fly

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This is another good website on flight cycles, but this one goes into much more depth about the physics and why things happen during flight.

http://www.ornithopter.de/english/principle.htm

The image to the right shows where the different forces, acting on a bird in flight, are located on the actual body of the bird. 

The following is a section of text that I have copied from the site which explains several different aspects i should be aware of when analysing a bird's flight...

The basic moving components of a bird wing in addition to the forward motion
are:
  • Flapping motion at the shoulder joint. In cruising
    flight the axis lies almost parallel to the axis of fuselage. Stroke
    angle, flapping frequency and time flow are within wide limits.  
  • Pulling or dragging of the outboard wing section during
    upstroke by the inboard wing section. Depending on the bird species and the
    flight situation this motion is pronounced very differently.   
    Inclination of the stroke plane. It is determined by the
    inclination of the stroke axis. Birds have the possibility to lift the stroke
    axis at the front in comparison to the fuselage and additionally, the axis of
    the fuselage in comparison to the flight direction.  
  • Twisting of the wing. It increases towards the wing tip
    - mostly during upstroke in the direction of a positive and during downstroke
    in the direction of a negative angle of incidence.  
  • Turning of the wing root, especially when flying with
    thrust and mostly in direction of the wing twisting. Such a thing is rarely
    visible among big birds in cruising flight.  
  • Sweep, especially of the outboard wing section during
    upstroke with the backward motion of the wing tip. In general, multiple
    sweepings are applied within a half span at the same time. Especially small
    birds use them. They fold up the wing during upstroke partially or
    completely.
  •  
    In order to understand better why the rock would move at a certain point, I have tried to research a bit more into the idea of inertia and the effect this would have on the movement of the rock.
    Here is a website explaining clearly the idea of inertia...

    http://www.physicsclassroom.com/class/newtlaws/u2l1b.cfm
     
    After being given a workshop and brief on how to create the stopmotion animation of a puppet pulling a very heavy stone, I have gone back to some of the videos I found earlier and took stills from them to try and analyse the movement of the body when pulling an object on a rope.
    The next thing to do after this will be to analyse it in more depth, take my own videos which would be more appropriate to the action that I want to animate and draw some key frames for me to work from when shooting the final animation.
     

    BestAnimationBooks.com

    http://bestanimationbooks.com/general/action-analysis-for-animators-excerpt-analysis-of-push-and-pull-motions#comments


    This article has a review on a book by Chris Webster which has a lot of detail about the human form when pushing or pulling an object.

    Animated Push

    This is an already existing animation on YouTube of someone pushing a box, which is very useful for me to be able to see what kind of action I need to include.
    Here is a real life video of a man pushing a car. This video is very useful as he pushes the car in a number of different ways, for example firstly he uses his hands to push it and then he turns around and uses his back.
    This other video is quite a comical animation of a character pulling on the rope of a heavy object.
    This video shows a man testing out the strength of a camera by attaching it to a car and then trying to pull the car with it. The profile shots of him pulling on the rope is very useful with an interesting shape in the body.