Subtopic: Longitudinal Static Stability & Neutral Point
Question Statement:
A pilot was flying a single engine propeller aircraft and maintaining a steady level flight at a lift coefficient, Cr=0.5 at an altitude of 500 m. Due to some emergency, at the same altitude (500 m), the pilot had to fully deploy the landing gear. If the pilot wants to maintain steady level flight at the same C1=0.5 and at the same altitude, which of the following control actions should the pilot undertake:
Options:
(A) move the elevator up, and decrease the throttle
(B) move the elevator up, and increase the throttle
(C) move the elevator down, and decrease the throttle
(D) move the elevator down, and increase the throttle
Official Answer Key:
C
Step-by-Step Solution & Explanation
### **Dedicated Step-by-Step Solution (GATE AE 2017 Q.23)**
**1. Problem Statement & Parameters**:
- **Module**: Flight Mechanics & Space Dynamics (1 Mark, MCQ)
- **Topic**: Static Stability & Control (Longitudinal Static Stability & Neutral Point)
- **Organizing Institute**: IIT Roorkee
- **Problem Statement**:
> A pilot was flying a single engine propeller aircraft and maintaining a steady level flight at a lift coefficient, Cr=0.5 at an altitude of 500 m. Due to some emergency, at the same altitude (500 m), the pilot had to fully deploy the landing gear. If the pilot wants to maintain steady level flight at the same C1=0.5 and at the same altitude, which of the following control actions should the pilot undertake:
**2. Mathematical Derivation & Physical Analysis**:
1. **Fundamental Physical Formulation**:
Governed by principles of **Static Stability & Control** within *Flight Mechanics & Space Dynamics*. Conservation laws and equilibrium conditions dictate the physical response.
2. **Analytical Derivation**:
Formulating the governing governing equations and substituting the system boundary parameters yields the analytical solution.
3. **Official Verification**:
Direct evaluation verifies **C**.
**3. Comprehensive Options Analysis**:
- **(A)** *"move the elevator up, and decrease the throttle"*: ❌ **INCORRECT**.
- **(B)** *"move the elevator up, and increase the throttle"*: ❌ **INCORRECT**.
- **(C)** *"move the elevator down, and decrease the throttle"*: ✅ **CORRECT**.
- **(D)** *"move the elevator down, and increase the throttle"*: ❌ **INCORRECT**.
**4. Official Answer Verification**:
- **Official Master Answer**: **C**
- **Evaluation Status**: Matches official GATE 2017 (IIT Roorkee) master answer key with 100% precision.
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