Balloon

Balloons are a type of aircraft that is supported in air by buoyancy, which in effect, makes the airship lighter than air.

During the American Civil War, the Union Army utilized observation balloons that were tendered at around six hundred feet high. 

According to a diagram drawn by Robert H. Goddard, the height limit for a balloon (on Earth) was 20 miles. (Star Trek: Enterprise)

Types of balloons

 * Dirigible
 * Hot-air balloon
 * Weather balloon

Background
The operated and/or built eight hydrogen-gas balloons from 1861 – 1863.
 * Small balloons: Enterprise, Eagle, Constitution, and Washington
 * Large balloons: Union, Excelsior, Intrepid, and United States

Ballon Ballon