Propulsion on craft

So I noticed a lot of craft have 3 bright glowing spots (or more like the Phoenix sighting) on the underside. Glowing orbs seem to be the most common type of UFOs seen. Anyone else think they are just orbs that we found and retrofitted to the underside of a craft body? I think that would explain a lot. There seem to be two different kinds of orbs. Some seem almost sentient moving very fluidly and other seem programmed to do a specific thing. Cough mh370 cough