10 Differences Between a ramjet and scramjet

Difference between a Ramjet and Scramjet

Difference between a Ramjet and Scramjet

What is a Ramjet

A ramjet is an air-breathing jet engine designed for high-speed flight. It operates on the principle of the air entering the engine being compressed before combustion without the need for a compressor. It is primarily used at high speeds, typically above Mach 2.

Examples of a Ramjet

Some examples of ramjet engines include the ramjet-powered missile engines used in military applications, such as the BrahMos supersonic cruise missile and the Meteor air-to-air missile.

What is a Scramjet

A scramjet, short for supersonic combustion ramjet, is a variant of the ramjet engine. The key difference is that a scramjet operates efficiently at hypersonic speeds, typically above Mach 5. It achieves combustion by compressing the incoming air using high vehicle speed rather than relying on a compressor.

Examples of Scramjet

Scramjets are still in the experimental stage and have not been deployed for commercial or military applications on a large scale. Some notable examples of scramjet tests include the X-51A Waverider and the HyShot projects.


Ramjet Scramjet
Difference Area Ramjet Scramjet
Operating Speed Typically above Mach 2 Typically above Mach 5
Type of Compression Compressed by internal components (compressor) Compressed by high vehicle speed
Combustion Method Subsonic combustion Supersonic combustion
Efficiency Limited efficiency at hypersonic speeds Efficient at hypersonic speeds
Applications Used in missiles and high-speed military aircraft Experimental stage; potential for space exploration and hypersonic aircraft
Altitude Range Operates at lower altitudes Potential for operation at higher altitudes
Complexity Relatively simpler design compared to scramjets More complex design due to supersonic combustion
Required Start Speed Requires external support (rocket or catapult) to reach operational speeds Requires higher starting speeds (~ Mach 4) for self-sustained operation
Stability More stable due to lower speed range Less stable due to higher speed range
Development Stage Developed and operational Still in the experimental stage


In summary, ramjets are primarily used in high-speed military applications and operate at speeds above Mach 2. On the other hand, scramjets are experimental and designed for hypersonic speeds, typically above Mach 5, for potential applications in space exploration and hypersonic aircraft.

Knowledge Check:

  1. True or False: Ramjets operate efficiently at hypersonic speeds.
  2. False

  3. Which type of compression is used in ramjets?
  4. Compressed by internal components (compressor)

  5. What are the potential applications of scramjet technology?
  6. Space exploration and hypersonic aircraft

  7. What is one difference in the altitude range between ramjets and scramjets?
  8. Ramjets operate at lower altitudes, while scramjets have potential for operation at higher altitudes.

  9. Which type of combustion method is used in scramjets?
  10. Supersonic combustion

  11. Which engine requires higher starting speeds for self-sustained operation?
  12. Scramjet (~ Mach 4)

  13. True or False: Scramjets are widely deployed for commercial purposes.
  14. False

  15. Which engine has a relatively simpler design?
  16. Ramjet

  17. True or False: Ramjets are more stable than scramjets.
  18. True

  19. What is the development stage of scramjets?
  20. Still in the experimental stage

Related Topics:

  • Difference between Turbojet and Ramjet Engines
  • Advantages and Disadvantages of Hypersonic Flight
  • Future of Supersonic and Hypersonic Travel

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