Teaching basic aerodynamics with a file card, ruler, and a penny

[StefanJ]

Sometimes I write things in my head on long car trips.

On the way down to Eugene, OR for the Mini Maker Faire on Saturday, I worked through a lesson plan that teaches the background to stability with a filing card, a ruler, a penny, and some tape.

You can demonstrate the concept of center of gravity with the ruler. Same amount of mass on either side of the 6" line, and that's where it balances.

Center of pressure, you can show with the index card. Same amount of resistance to air on either side of the center line, and when you drop it, it tends to flutter down around this center.

From there, you modify your instruments. Tape a penny to various points of the ruler. Bend back flat the corners of the index card, reducing the air resistance on one end. Show how this changes the mass balance point of the ruler, and the aerodynamic balance point of the card . . . you can now throw the card!

Then combine things. Tape the penny to the center of the card and throw it. Move it up toward the folded-over ends (changing the center of mass) and throw it again.

I think you get the picture. If anyone is itnerested I could write this up more formally.

 

[Marc_G]

The kids would say, "What's a filing card? You mean, like a memory stick?"

:roll:

 

[RadManCF]

That's a good idea, it emphasises to the kids that rocketry isn't all propulsion, the areodynamics are important also.

 

[fyrwrxz]

Stef- I'd go ahead and fully develop this. It's a great lesson plan a teacher could use as a precursor to 'one of us' coming in for a 'rocket class'. It's perfect! With minimal investment the lesson demonstrates the basics in a very understandable way and it won't turn off the science impaired youth with all the 'physics jargon' that makes them tune out so fast. I used to break yardsticks using 'air pressure' on a sheet of typing paper after betting the class I could break the stick with a piece of paper.
lay the yardstick on the desk hanging over just under a half length, cover with the paper and hit the overhanging part with your hand sharply=broken yard stick. Air pressure? 14.7 PSI It was a start to a lively class (most of time...)