Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Aerospace Falling from an aircraft effects?

  1. Jun 29, 2004 #1
    Falling from an aircraft....effects???

    Deploying something from an aircraft or helo.....what are the different forces that are going to act on that object, or rather, where would I find information about that. Say a relatively light box is dropped out of a moving helo, how would I go about figuring out what happens to the box if the helo is moving at V knots and the box is LxWxH and its mass is M? I figured that it the box is too light, some sort of air displacement could cause it to act "odd" and could cause a serious accident or injury to the flight crew.

    Any help would be greatly appreciated.

    ***never stop learning***
  2. jcsd
  3. Aug 5, 2004 #2
    Not sure what you mean by "act "odd"... I don't see how dropping a box that is "too light" could cause a "serious accident". The forces on a dropped object I know about are gravity, air friction, and perhaps the push of a rotor, all of which push things from an aircraft away from the aircraft.
  4. Aug 8, 2004 #3


    User Avatar

    Well, if you're throwing something out of an airplane, it's going to slow down because of air resistance, and may hit other parts of the exterior as it does so...possibly including jet intakes/props, depending on where it's ejected from the fuselage. This might harm the crew...not directly, of course, but the results may not be pretty.

    In terms of a general effect on the box...it will accelerate towards the ground at 9.8m/s^2, less air resistance, until it hits critical velocity. It's initial forward speed relative to the ground will be the velocity of the aircraft it's thrown from for a very short time, until it slows down because air resistance.

    Perhaps what you are thinking about in your reference to a "light box" is some form of turbulence along the hull that would throw it back in. If so...that is theoretically possible, but incredibly difficult to calculate...and you'd need a CRAY on hand to do it.
  5. Aug 8, 2004 #4


    User Avatar
    Science Advisor

    Greetings !

    Could it be that you wanted to imply low mass density ?
    Well, abviously if the mass density of the object is lesser
    than that of the air at the drop altitude it will go up.
    If its greater than it will go down. I believe, that if the mass density is considrably greater than that of the surrounding air, this
    effect will be neglagible compared to gravity and air resistence.

    As others here said with a jet engine its pretty simple to figure out
    the effect, but with a rotor it could be a lot more difficult.

    Live long and prosper.
  6. Aug 10, 2004 #5
    Turbulence I guess.

    I think what I was looking for was if any upward turbulance, towards the rotor, was generated by the rotor. I wouldn't want the package to somehow be sucked, or blown back up into the general vicinity of the rotor.

    Thanks for all the input.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook