Kawaida ili ndege ipae angani inahitaji mafuta "fuel" na kisaidizi cha kuunguza mafuta"oxidizer",kwa ndege zinazoruka karibu na uso wa Dunia hubeba "fuel" tu,oygen iliyopo angani hutumika kama "oxidizer",ila anga za juu(high altitude) hakuna oxygen,hivyo basi ndege zilukazo anga za juu hulazimika kubeba "fuel" pamoja na "oxidizer"(note that fuel may be in the form of solid or liquid form,thus the internal combustion within a rocket engine of fuel together with the carried oxidizer accompanied together with the mist formed in high altitude is what we see as a thick smoke)