Here is a page from the F-104 flight manual. It shows the flight envelope for the F-104 Starfighter with the powerful J79-GE-19 turbojet engine:
I have a question regarding the shape of the afterburner envelope.
In Aerodynamics for Naval Aviators, published in 1965, the author, Hugh Harrison Hurt, Jr., states:
The thrust added by the afterburner of a turbojet engine is not affected so greatly by altitude as the basic engine thrust. The use of afterburner may provide a thrust increase of 50 percent at low altitude or as much as 100 percent at high altitude.
Why is military thrust (basic engine thrust) greatly impacted by altitude, and afterburner thrust is not?