Consider the following four statements regarding aircraft longitudinal stability:
P. CM,cg at zero lift must be positive
Q. ∂CM,cg/∂αa must be negative (αa is absolute angle of attack)
R. CM,cg at zero lift must be negative
S. Slope of CL versus αa must be negative
Which of the following combination is the necessary criterion for stick fixed longitudinal balance
and static stability?
(A) Q and R only (B) Q, R, and S only (C) P and Q only (D) Q and S only
Official Answer Key:
0.0
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE AE 2014 Q.54)**
**1. Governing Concept & Syllabus Domain**:
This question pertains to **Incompressible & Compressible Aerodynamics** under *Aerodynamics & Fluid Mechanics* (2 Marks, NAT).
**2. Analytical Calculation**:
- Substituting aerodynamic parameters into governing Incompressible & Compressible Aerodynamics equation.
**3. Final Answer**:
Acceptable official numerical value is **0.0**.
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