• Question: what keeps planes helicopters and helium balloons in the air?

    Asked by hermionie star to Rob, Martin, James, Elizabeth on 10 Mar 2015.
    • Photo: Robert Woolfson

      Robert Woolfson answered on 10 Mar 2015:

      They’re actually all kept in the air by different things.

      Helium balloons float because helium is lighter than oxygen and nitrogen (the main gases in the air) and so it rises up.

      Helicopters and planes use something called lift to stay in the air. The blades of a helicopter have a very similar shape to the wings of a plane. As they move through the air, air moves faster over the top of them which creates a force called lift (a difference in air pressure above and below the wings). When they’re moving fast enough, this lift is enough to keep planes and helicopters flying.

      Hope than answers your question.

    • Photo: James Coombs OBrien

      James Coombs OBrien answered on 10 Mar 2015:

      Great question.
      The reasons that planes and helicopters can fly is different from why helium balloons float.

      When you hold a helium filled balloon you can probably tell how light it is (not like planes!), so light that it tries to escape. This is because helium is a very light gas (the second lightest after hydrogen). Since it is lighter than air it floats upwards, in fact the gas helium is so light it can actually escape the earth and float off into space!

      Planes and Helicopters rely on pure power to get them off the ground as well as sometime called aerodynamics. I must admit I don’t know a lot about aerodynamics, you’ll have to ask an engineer!.

      Thanks a lot.

    • Photo: Elizabeth Cooper

      Elizabeth Cooper answered on 11 Mar 2015:

      Helium is lighter than air therefore its floats. If a gas is heavier than air such as argon this will sink to the floor.

      Helicopters have blades and when rotating air flows more quickly over the tops of the blades than it does below. This creates enough lift for flight.

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