Home >> Hobbies >> Other Hobbies

How to Keep a Rocket From Tumbling

What keeps a model rocket -- or any rocket, for that matter -- from tumbling in flight is the relationship between its center of gravity and center of pressure. A rocket will be stable if its center of gravity is ahead of its center of pressure by a distance that is equal to at least one half of the rocket's diameter. Commercial model rocket kits are tested to make sure that the center of gravity is sufficiently ahead of the center of pressure. When you are designing your own rocket, though, you won't know that unless you test the rocket first.

Things You'll Need

One yard of string
Plastic modelling clay
Additional model rocket fins and nosecones

Instructions

Testing your rocket
- 1
  Find the center of your rocket's gravity by balancing it in a loop of string.
- 2
  Tie one end of the string around the rocket right at the center of gravity.
- 3
  Find an area large enough where you can swing the rocket around without hitting anyone or anything. Holding the free end of the string, slowly start swinging the rocket around your head and steadily increase the speed until the string is almost perpendicular to your body.
- 4
  As you swing the rocket around your head, watch to see if it is traveling in a straight line or if its nose or tail is dropping down. If it is traveling in a straight line, your rocket is properly balanced and it is safe to fly. If the nose is tilting either up or down as you swing the rocket, it means you need to change the location of the rocket's center of gravity or its center of pressure
How to fix your rocket's balance
- 5
  If the nose of your rocket is tilting up, then you need to move the rocket's center of gravity forward. You can do this either by exchanging the current nose cone for a heavier one, or by adding plastic modelling clay to the inside of the current nose cone. After you change the weight of the nose cone by either swapping it out for a new one or adding weight to it, test the rocket again, just as you did before.
- 6
  If the nose of your rocket is tilting up, then you need to move the center of pressure farther back. To do this, you can either add larger fins or you can move the fins back on the rocket's body. You can even construct your rocket so that a large part of the fins sticks out past the end of the body. As in changing the weight of the nosecone, test your rocket after you make any alterations to the fins to make sure you have moved the center of pressure far enough back.
- 7
  After replacing the fins or nose cone, or adding clay to the nose, follow the steps in Section One to test your rocket again and see if it is now properly balanced. If it isn't, go back and readjust the nose or the fins and retest your rocket until it is.

Other Hobbies