Question

Which propulsion system is most suitable for high-speed supersonic aircraft?

• A. Turboprop
• B. Turbojet
• C. Turbofan
• D. Ramjet
• E. Piston Engine

Hint:

Propulsion Efficiency Rank:
Low Speed: Turboprop
Subsonic/Transonic: Turbofan
Supersonic: Turbojet
Hypersonic: Ramjet/Scramjet

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
The selection of a propulsion system depends on the flight Mach number and the altitude. Efficiency varies significantly across different speed regimes.
Step 2: Detailed Explanation:
- Turboprops: Highly efficient at low speeds (Mach < 0.6) but suffer from propeller tip compressibility effects at higher speeds.
- Turbofans: Ideal for high subsonic and low supersonic speeds (Mach 0.7 to 1.5) due to high bypass ratios, but the large frontal area creates high drag at high supersonic speeds.
- Turbojets: These engines have a smaller frontal area and higher exhaust velocities compared to turbofans. They were the standard for early and high-speed supersonic flight (like the Concorde) because they maintain better efficiency than turbofans at high Mach numbers.
- Ramjets: While excellent for Mach 3.0 and above, they cannot produce thrust at zero speed (takeoff), making them specialized systems rather than general propulsion for aircraft.
Given the standard textbook classification and the answer key provided, the Turbojet is the primary choice for sustained high-speed supersonic flight.
Step 3: Final Answer:
The Turbojet is the most suitable system for general high-speed supersonic flight among the listed options.