APU - Auxiliary Power Unit
One sign of the military origin of the Breitling Super Constellation are the big openings in the right side tail section. That's the place where the APU - The Auxiliary Power Unit - is installed. It makes the necessary electric energy to start the engines. The APU itself is started from battery power.

Non-military Connies needed some external "help" from outside to start the engines. A small cart with a generator or transformer was connected to the plane and supplied the necessary energy. Military Connies sometimes had to fly to remote airfields with not much more than a runway. They had to produce their own energy.

For the Super Constellation Flyers this additional equipment is very useful. Without it, it would be impossible or very difficult to fly home from small airports. The necessary devices are not available everywhere.

This big gray metal box is the APU in the tail of the airplane. The rectangular tube on the right side is the air intake, the big round tube going downwards is the exhaust.

Through the round opening you can see the toilets behind them the APU is located. The many wires that go across move the elevators and rudders.

The APU controlpanel is on the right side high above the head of the Flight Engineer.

On civil Connies there is only an empty space...

Starting of the APU is very simple - Push the starter switch until the temperature starts to rise. Then watch if everything is in the green area.