In the field of aerodynamics, dynamic pressure, a combination of air density and speed, is called "Q". When a rocket is launched, the rocket accelerates and Q increases. As the rocket ascends though the atmosphere, air
density decreases, and there is a point where the combination of increasing speed and
decreasing density is a maximum. This point is called "Max Q." From this point on, the rocket continues to accelerate as it ascends through the atmosphere, but also air density continues to decrease, so that the increasing velocity of the rocket does not contribute to an increase in dynamic pressure. This is neatly illustrated in the following graph showing the dynamic pressure and velocity of a simulated Saturn Five passing through the atmosphere. HereMax Q is achieved eighty seconds after launch, approximately fifteen seconds after the simulated rocket has passed through the sound barrier.
In the following photograph of a Saturn Five, the condensation cloud forming around the lower half of the rocket indicates that it is passing through the sound barrier, and that it will soon reach Max Q.
Carter Kaplan has taught in Montana, North Dakota, Ohio, West Virginia, Pennsylvania, New Jersey, New York City, and Scotland. His work includes a book on Wittgenstein and literary theory, Critical Synoptics: Menippean Satire and the Analysis of Intellectual Mythology. Articles on “Karel Čapek,” “Menippean Satire” and “Dystopian Literature” appear in The Encyclopedia of Literature and Politics. He has contributed a chapter on William Blake and Michael Moorcock to New Boundaries in Political Science Fiction. Author of the novel Tally-Ho, Cornelius! and the Aristophanic comedy Diogenes. Editor of Emanations, Emanations: Second Sight, Emanations: Third Eye, Emanations: Foray into Forever, Emanations: 2 + 2 = 5, the IA edition of The Scarlet Letter, which includes his afterword, "A" is for Antinomian: Theology and Politics in The Scarlet Letter. He is editor of the anthology Fantasy Worlds. He is co-translator and editor of the IA edition of Creation of the World by Torquato Tasso.