Wing shapes and sizes of both birds and planes determine how they might perform or what they might be capable of (for example, gliding, sustained high speed and manoeuvrability). One way in which the shape of the wing can be described is through wing aspect ratio.
Wing aspect ratio
The ratio of the length of wings to their width is called aspect ratio. A high aspect ratio indicates long, narrow wings. A low aspect ratio indicates short, wide wings.
Aspect ratio = wing length (m)/wing width (m)
Generally, high aspect ratio wings give slightly more lift and enable sustained, endurance1 flight, while low aspect ratio wings are best for swift manoeuvrability.
High aspect ratio wings
Stability: Long narrow wings give a plane or bird more stability. (It’s a bit like a tightrope walker who holds a long pole across their body as they walk along the rope – the extra ‘arm’ lengths help to balance the body by adding more mass2 to either side of it.) The trade-off is that this type of plane won’t be very manoeuvrable.
Less induced drag Long, narrow wings also have less induced drag3 than shorter wider wings. Induced drag4 is created at the tips of the wings where the high pressure5 air from beneath the wing comes up over the wing tips into the low pressure6 zone. This meeting place of different air pressures becomes a turbulent area creating induced drag. Long narrow wings have less end edges (tips) and more stable wing area than shorter wider wings so they have less drag.
Less fuel consumption: Having less induced drag means there is less fuel7 consumption for planes and birds (fat consumption) so they can keep their speed for a longer time than short wide-winged fliers.
Low aspect ratio wings
Higher fuel consumption: Shorter wider-winged planes and birds have a bigger wing tip edge, which means more induced drag. This means they go slower unless they have extra power to counteract the drag. More fuel would be needed to keep them at a constant speed8.
More manoeuvrable: The less stable wing area means the low aspect ratio wing is more manoeuvrable than the high aspect ratio wing. The peregrine falcon, for example, tucks its wings in (producing a low aspect ratio) for swift manoeuvrability.
Aspects ratios and wing loading are combined for different flying capabilities. For example, high aspect ratio combined with low wing loading9 is used for slow flight such as gliding or soaring.
Wings for flight
Helicopter
Albatross
Airbus
Glider
Falcon
Spitfire
Hawk
Spy plane
Swing-wing bomber
King vulture
Hummingbird
GodwitSoaring
Speed
Gliding
Havering
Manoeuvering
Endurance
Unused items
- Helicopter
- Albatross
- Airbus
- Glider
- Falcon
- Spitfire
- Hawk
- Spy plane
- Swing-wing bomber
- King vulture
- Hummingbird
- Godwit
Activity ideas
Continue the learning with your students with one or more of these activities
- Birds and planes – explore the importance of wing shape and size and how this determines the flight capabilities of birds and planes.
- Aerofoils and paper planes – learn how to make an aerofoil10 and to make and fly paper planes.
- Making a glider – handcraft a glider from balsa wood and in the process learn about aerofoil wing shape, glider parts and terminology. Then experiment with flight using variables of wind and nose weight11.
- Observing wings for flight has suggestions on how to use the interactive Wings for flight graphic organiser. Wings for flight is useful as a pre-test or post-test for summative assessment.
- endurance: Ability of a muscle to produce force continually over a period of time.
- mass: The amount of matter an object has, measured in kilograms.
- induced drag: Resistance that is a consequence of lift. It is caused by airflow passing over a wing.
- drag: Sometimes called air resistance or fluid resistance, drag refers to forces that oppose the relative motion of an object through a fluid (a liquid or gas).
- pressure: The force per unit area that acts on the surface of an object.
- low pressure: In aerodynamics, low pressure is formed over the top of an aerofoil (wing) as it moves through the air because the air particles become 'stretched' out as they travel faster over the upper surface towards the wing.
- fuel: 1. A combustible substance that provides energy. 2. A body fuel such as fat, carbohydrates and protein that supplies energy for animals’ activities.
- constant speed: When the speed of an object such as a cyclist stays the same. If forces are balanced, the cyclist will travel at a constant speed.
- wing loading: The loaded weight of an aircraft or weight of a bird divided by the total surface area of the wings.
- aerofoil: A specially shaped structure designed to produce lift for flight. It usually refers to a wing that is curved and narrows to a sharp trailing edge.
- weight: Force due to gravity acting on an object, measured in newtons.
#/media/File:Dg800.jpg){kind=link}