Product: Toy: Ball
spear sphere   (+1)  [vote for, against]
like a Hoberman sphere but different

This is a toy that changes from a cylindrical shape into a spherical shape.

The toy comprises a small inner sphere with a number of pivotally mounted arms covering its surface. When two opposed outer shells move towards the inner sphere, the arms pivot from a longitudinal direction to a radial direction. (see illustration)

The two opposed outer shells are connected with a spring which pulls them together. The outer shells can be pulled apart by the user and locked into the cylindrical configuration.

This toy can be used for many different applications.

If the device were covered with a flexible sheet it could be used as a collapsible ball.

One hemisphere covered with a flexible sheet could be used as an umbrella.

I initially thought of it as a cool firework: a mortar fires the device into the sky in its cylindrical (or spear) configuration. At the apex of its trajectory the device then pops into its spherical configuration. Fireworks are attached tangentially to the sphere so that the sphere rotates as it falls to Earth.
-- xaviergisz, Jun 13 2007

This subject was in a book I read, recently, about Nano design in nature. Can't quite remember the relationship. [Ling, Jun 14 2007]

Somehow, I am reminded of Sputnik. Regarding your concept of collapsing/expanding structures, I wonder if tensegrity stuctures could be utilised, where the tension parts are elasticated? Tensegrity structures have compression members which do not touch each other, but are linked by tension members. Somehow, all the tensions keep everything rigid.
-- Ling, Jun 14 2007

A queer spear sphere fear? Steer clear!
-- Ling, Jun 14 2007

random, halfbakery