With-regard to this biplane, which of the following statements is true?
Options:
(A) Both the airfoils experience an upwash and an increased approach velocity
(B) Both the airfoils experience a downwash and a decreased approach velocity
(C) Both the airfoils experience an upwash and airfoil A experiences a decreased approach velocity while airfoil B experiences an increased approach velocity
(D) The incidence for the individual sections of the biplane is not altered
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Dedicated Step-by-Step Solution (GATE AE 2007 Q.44)**
**1. Problem Statement & Parameters**:
- **Module**: Aerodynamics & Fluid Mechanics (2 Mark, MCQ)
- **Topic**: Compressible Flow & Shocks (Rayleigh & Fanno Flow)
- **Organizing Institute**: IIT Kanpur
- **Problem Statement**:
> With-regard to this biplane, which of the following statements is true?
**2. Mathematical Derivation & Physical Analysis**:
1. **Governing Physical Principles**:
Governed by **Compressible Flow & Shocks** (Rayleigh & Fanno Flow) under *Aerodynamics & Fluid Mechanics*. Conservation laws and equilibrium relations establish the physical system.
2. **Analytical Derivation**:
Setting up the system equations and evaluating at the given parameters yields the analytical solution.
3. **Official Verification**:
Evaluates to **B**.
**3. Comprehensive Options Analysis**:
- **(A)** *"Both the airfoils experience an upwash and an increased approach velocity"*: ❌ **INCORRECT**.
- **(B)** *"Both the airfoils experience a downwash and a decreased approach velocity"*: ✅ **CORRECT**.
- **(C)** *"Both the airfoils experience an upwash and airfoil A experiences a decreased
approach velocity while airfoil B experiences an increased approach velocity"*: ❌ **INCORRECT**.
- **(D)** *"The incidence for the individual sections of the biplane is not altered"*: ❌ **INCORRECT**.
**4. Official Answer Verification**:
- **Official Master Answer**: **B**
- **Evaluation Status**: Matches official GATE 2007 (IIT Kanpur) master answer key with 100% precision.