Introduction / Context:
Understanding propulsion naming—propeller (airscrew), turboprop, turbojet, and turbofan—is essential in aerospace engineering. This question tests precise definitions rather than casual phrasing.
Given Data / Assumptions:
- A propeller converts engine power into aerodynamic thrust, not “speed”.
- Turboprops: turbine engine drives a propeller.
- Turbojets: thrust comes directly from the turbine engine exhaust flow.
- Turbofan: a ducted fan mounted ahead of the core (turbojet-like) engine provides most thrust.
Concept / Approach:
Terminology hinges on what produces thrust: a propeller disc (turboprop), jet exhaust (turbojet), or a large fan plus core exhaust (turbofan). Precise words matter for correctness.
Step-by-Step Solution:
1) Statement 1 is incorrect: an airscrew converts engine output into thrust (a force), which then produces speed depending on drag and power available.2) Statement 2 is correct: turboprops are propellers driven by turbine engines.3) Statement 3 is correct: turbojets derive thrust directly from high-velocity jet exhaust produced by the turbine engine core.4) Statement 4 is correct: turbofan aircraft have a fan in front of the core; most modern transports are high-bypass turbofans.
Verification / Alternative check:
Check standard propulsion taxonomy—thrust source differentiates the types.
Why Other Options Are Wrong:
Any option including Statement 1 as correct is invalid because “thrust” is the correct output, not “speed”.“All of the statements” is wrong due to Statement 1.
Common Pitfalls:
Equating thrust directly with speed; ignoring that speed depends on thrust vs drag balance.
Final Answer:
Only statements 2, 3, and 4 are correct.
Discussion & Comments