I fly model jets that utilize miniature gas turbine engines. If one wishes to introduce a smoke system, A smoke oil tank is installed on board, The smoke oil fluid is then pumped from the tank to a spray nozzle located at the exhaust outlet of the turbine (thrust nozzle). The smoke oil is then introduced to a 1200+ Degree stream of exhaust gas from the turbine and reacts to form a very dense white smoke trail. I am interested in making a "black" smoke trail. What could be used to yield this result? Thanks!