I think that they are some kind of help engines for take off from your aircraft.
Yes exactly. They are rocket engines who you need to take off and after the take off you drop they.
They are German R.A.T.O. pods or Rocket assisted take off pods. They are automatically on your aircraft when you airstart and drop immediatly. Try a mission from the ground with a full bomb load and you will get them. They help the Jet get up to speed so the engines can have enough airspeed to produce thrust.
They also used them on 110's pulling gliders and ME-323 Gigant gliders loaded to help them get airborn.
Makes much more sense now. Thanks Guys.