# 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

## Audiovisual Resources

It is recommended that teachers should view any video before purchase.

• Marcom Projects: How an Aeroplane Works

## Practical Activities

Wind Tunnels Plans