Science Buddies: "Ask an Expert"

Hi, I am trying to attempt the science fair project, Winglets in Windtunnels https://www.sciencebuddies.org/science- ... p012.shtml
but am having trouble understanding how wind tunnels work. When I test the wings in the wind tunnel, how would i know how good the wing is in comparison to others. Basically, my question is, how can I measure how effective the wings are when measuring it in the wind tunnel. Please answer soon! Thanks!

ChallengerS1 - There are a couple references in the Science Buddies website that you should review. The first is a site within the Forums that you can find at this link.

https://www.sciencebuddies.org/science- ... m.php?f=47

The second is actually a post from Amy Cowen relating to the wind tunnel experiment.

https://www.sciencebuddies.org/science- ... -toc.shtml

See if these answer your questions, if not, come back to the expert forum so we can try to assist you with specific issues.

Rick Marz

Hi, challengers1,

Some plausible methods i would consider it timing it with a stopwatch from when you turn it on the when the plane leaves the tunnel, or using a (slomo) camera - like from a smartphone. A regular camera works fine also, but will have less frames. You could do a side by side and measure the number of frames rather than the stopwatch. This method would be more effective as it reduced human error.

-Chris

I saw a project done along these lines several years ago.

The individual was testing different miniature kite designs in a wind tunnel.

His approach was to measure how fast he had to run the fan to get the kite to fly - flying with "less wind" was considered superior.
Another way to do it would be to see how much weight an airfoil could "lift" for a given wind strength.

The linked-to experiment gives three possible things to measure.

1. lift - see how much weight you can put on the airfoil for a given wind strength before it does not fly
2. drag - probably you attach the airfoil to a scale and see how much it "pulls" when it is flying at a given wind strength (less drag will pull less hard on the scale)
3. airflow "visualization" - blowing smoke or some other visible effect over your airfoil to see what the wind is doing.

I'd add a fourth - stability. A good airfoil doesn't vibrate, flip over or come apart when put under expected wind strength. The smaller structures on a wing tend to be designed to help with this, where the main wing shape tends to affect lift and drag (or can move, allow the pilot to adjust lift or drag on each wing to allow for turning, braking, etc)