Bright or invisible rocket exhaust

LOX and RP-1 never burn absolutely clean, and there is always a bit of free carbon in the exhaust, which produces a luminous flame. So when you’re looking at TV and see a liftoff from Cape Kennedy—or from Baikonur for that matter—and the exhaust flame is very bright, you can be sure the propellants are Lox and RP-1 or the equivalent. If the flame is nearly invisible, and you can see the shock diamonds in the exhaust, you’re probably watching a Titan II booster burning N₂O₄ and 50–50.

Clark, John D. Ignition! An Informal History of Liquid Rocket Propellants. Rutgers University Press Classics, 2017. p. 96

Author: Milan

In the spring of 2005, I graduated from the University of British Columbia with a degree in International Relations and a general focus in the area of environmental politics. Between 2005 and 2007 I completed an M.Phil in IR at Wadham College, Oxford. I worked for five years for the Canadian federal government, including completing the Accelerated Economist Training Program, and then completed a PhD in Political Science at the University of Toronto in 2023. View all posts by Milan