Did you know that the Wright brothers figured out one of the biggest leaps in propeller technology?  Prop blades had basically stayed the same for about 2,500 years until they figured out to take an airplane wing, turn it sideways and rotate it to create thrust.  The main idea being a wing is that it needs to have a half-twist and the thickness needs to vary along its length (this is because you want to get the same amount of thrust at each point along its length, or one part of the propeller will generate more thrust and rip itself apart).

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4 Responses to “Roto-Helicopters”

  1. The paper helicopter spins because as it falls, air pushes up against the bottom of the blades, twisting them slightly out of shape (bending one side of the blade up more than the other) which makes the copter spin. Did you notice if your helicopter spins clockwise or counter-clockwise? You can change the spin direction by bending the ‘ears’ (blades) in the opposite direction. Try making a copter with only one blade and see what happens!

  2. I am experimenting with the roto-copter. Why does it spin and why does it spins the other way when I flip the ears?

    Thank you.

    Jacob, age 10

  3. Cindy Martin says:

    My kids had a great time making roto-helicopters of all sizes and using different papers (construction, copy paper and card stock). They took note of the differences (size, weight, speed of drop and twill speed) and drew their own conclusions.

    Definitely a hit in our house. Thanks!

  4. Logged in for the first time last night and now there are a whole fleet of roto-copters flying down my stairwells.

    Thank you for the fun!