Rocket engines — basic characteristics: Which statements correctly describe rocket combustion chambers and exhaust compared with air-breathing jet engines?

Introduction / Context:
Rocket propulsion differs fundamentally from air-breathing jets because the oxidizer is carried onboard. Recognizing chamber conditions and exhaust characteristics is key to nozzle design and mission performance estimates.

Given Data / Assumptions:

• Steady operation of a chemical rocket with a converging–diverging nozzle.
• Combustion completes in the chamber before the nozzle throat.
• Nozzle expands flow from high chamber stagnation conditions to near-ambient or vacuum pressure.

Concept / Approach:

The chamber behaves as a high-pressure plenum with near-stagnation velocity, analogous to a supersonic tunnel reservoir. The nozzle then accelerates the gases to very high supersonic speeds, typically exceeding air-breathing turbojet exhaust velocities because chamber temperatures and pressure ratios are much higher and no intake losses occur from atmospheric compression systems.

Step-by-Step Solution:

Verification / Alternative check:

Rocket nozzle theory shows exit Mach numbers and velocities determined by pressure ratio and chamber temperature; flight data confirm much higher exhaust speeds than jets which are limited by turbine inlet temperature and intake compression ratios.

Why Other Options Are Wrong:

Choosing any subset omits true statements; “None” contradicts standard gas-dynamics.

Common Pitfalls:

Confusing rocket nozzles with ram/scramjet intakes; overlooking that jets entrain ambient air and are constrained by Brayton cycle components.

Final Answer:

All of the above