Consider the following statements:
1. Ramjets operate efficiently at hypersonic speeds.
2. Dual Mode Ramjets can work in both subsonic and supersonic modes. Which of the statements given above is/are correct
Show answer & explanation
Correct answer: D
Explanation
Answer: 1 only
Explanation: The correct answer is 1 only.
Statement 1 is correct: A Ramjet is an air-breathing jet engine that works most efficiently at supersonic to hypersonic speeds (typically above Mach 2). It has no moving parts and relies on the aircraft’s forward speed to compress incoming air.
Statement 2 is incorrect: A Dual Mode Ramjet (DMRJ) can operate in subsonic combustion (ramjet mode) and supersonic combustion (scramjet mode), but it does not operate in both subsonic and supersonic airflow modes in the way stated. The statement is misleading because it confuses flow regimes with combustion modes.
Additional Key Facts
Ramjets become efficient only after reaching high speeds; they cannot produce thrust at zero velocity.
At very high speeds (above Mach 5), ramjets transition into scramjets (supersonic combustion ramjets).
Used in missiles and experimental hypersonic vehicles.
No compressors or turbines are used in ramjet engines.
Examples of related technologies:
BrahMos missile uses ramjet propulsion in some variants.
Potential Exam-Oriented Questions & Answers
Question: What is the full form of scramjet?
Answer: Supersonic Combustion Ramjet
Question: Why can't ramjets work at zero speed?
Answer: Because they require high-speed airflow for compression