Flight Termination Unit (FTU)

In order to have a better control of a real flight one would like to have a flight termination unit attached to his balloon line. This element is very useful because it helps detach a payload from balloons at a desirable set altitude or specific time. This is also very handy when one has to avoid a restricted airspace or an unwanted landing location (like a populated area, a lake or a sea).

The flight termination unit must be located above the parachute. The designs that have been proven more useful are the following:

  • Heating a ni-chrome wire with a power source to burn the nylon line through a string (also known as a hot wire cutdown).
  • Using a solenoid to release a knot.


Example of a cutdown circuit diagram. Source: bovineaerospace


Radar Reflector

The three perpendicular planes of a radar reflector ensure radar reflection from all directions making it visible to an aircraft radar at high altitudes and even in conditions of poor visibility. Although the usage of a radar reflector is not mandatory in many countries such as Spain, we recommend its usage to help avoid unlikable but avoidable and unnecessary collisions.

A radar reflector can be bought commercially or may be built by yourself. Although making a radar reflector is easy (all we need is some cardboard as a support surface and aluminum foil) we recommend buying it. A professional maker/manufacturer gives a guarantee that everything will work as planned and just in case of colliding, we will have the security that the radar worked properly because it was perfectly built.


An emergency radar reflector designed to be used for small boats that is also an ideal choice for high altitude balloonists. Source: davisnet