2.5 How do heavy things fly?
This study relies on the ability to take measurements during an investigation. Preparation of a form of wind machine or wind tunnel will need to take place prior to beginning this study. The purpose of the study is NOT to construct a wind tunnel. Plans for simple wind tunnels are available online. Simple tests of variables are able to be made with balanced wing sections. By measuring the effect for one set of variables, then comparing with another test by changing one factor is the purpose of this investigation. Simple variables are wing cross-section, wind speed, angle of attack, wing surface quality.
Difficult theory area- many text books are wrong!!
Note: The apparent disagreement between Bernoulli and Newton stems from the ‘equal time’ explanation given to Bernoulli. This is an incorrect interpretation of Bernoulli’s Theory. The two theories are in complete agreement, Newton uses the change of momentum, Bernoulli uses the difference in pressure. The measurement regimes provide that pressure is simpler to measure and compare between top surface and bottom surface of the wing. The momentum of the air before the wing and the momentum of the air after the wing is very difficult to assess. (called downwash effect)
Suitable Learning Activities are provided on page 61 of the 2013 - 2016 VCE Physics Study Design. These are also included here.
- suspend a model aircraft from a spring; balance in the airstream from a fan and investigate the forces.
- place a light ball in the stream of air from a vacuum cleaner hose and demonstrate the Bernoulli effect.
- discuss the effect of the various aerofoil surfaces of an aeroplane and their purposes.
- operate an electrically driven propeller on a varying voltage and measure the thrust–power relationship.
- discuss the various forces operating on an aircraft in flight and the effect of each of them.
Text Resources
- Shovel Fundamentals of Flight, Wiley Publications.
Material from the 2011 Physics Teachers Conference Proceedings by Dr Murray Anderson from Camberwell Grammar school and Peter Cheung from Nagle College
Basic Flight Dynamics 33.6 kB
Notes prepared by Peter Cheung, Nagle College
Wind Tunnel 25.2 kB
Three pages of notes on types and uses of wind tunnels prepared by Peter Cheung, Nagle College
Wind Tunnel Experiment: Results 88.6 kB
Three pages of notes on types and uses of wind tunnels prepared by Peter Cheung, Nagle College
Spreadsheet on Wind Turbine Efficiency 46.1 kB
Spreadsheet of results with graphs
Image of Wind Tunnel 939 kB
Another Image of Wind Tunnel 993 kB
Another Image of Wind Tunnel 1.04 MB
Audiovisual Resources
It is recommended that teachers should view any video before purchase.
- Marcom Projects: How an Aeroplane Works
Aerodynamics of Flight
Youtube video on the Aerodynamics of Flight, Uses Flash animation
Practical Activities
Wind Tunnels Plans
Wind Tunnel Plan No 1
5 page description from the US. A pdf file.
Wind Tunnel Plan No 2
Plans to construct your own professional wind tunnel. Designed by NASA Low cost project (can be built for less then US$250.00) This was designed to produce a steady airflow with no turbulence in the testing area. Designed to test scale model/s of your airfoil, fuselage, canopy etc.
Wind Tunnel Plan No 3
Ideal for model clubs, this practical testing apparatus gives good results. If you have the motor, building cost is small.
Useful Websites
NASA Dryden PDF document 'Flight Testing Newton's Laws'
Available free online.
Bernoulii or Newton's Laws for Lift?
Hyperphysics explanation of Lift. Both descriptions of airfoil lift are correct. Pressure differences are simpler to measure on a model wing than the ‘downwash’ forces flowing past the wing.
NASA: A Beginner's Guide to Aeronautics
Everything you would want to know, the website includes pages on "How do airplanes work? Why does a wing change shape on takeoff and landing?" and "What is a wind tunnel? How do engineers use wind tunnels". A large number of interactive simulators and movies are also available.