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TECH GENERAL — CH.9

Aircraft StabilityAircraft & Engines — DGCA CPL practice questions

Question 1 of 6

Positive static stability means that after a disturbance the aircraft initially:

A.Continues to diverge
B.Remains in the new position
C.Tends to return towards its original position
D.Oscillates with growing amplitude

All 6 questions — Aircraft Stability

Aircraft & Engines · DGCA CPL. The correct option is marked on each.

  1. Q1. Positive static stability means that after a disturbance the aircraft initially:

    • A.Continues to diverge
    • B.Remains in the new position
    • C.Tends to return towards its original position✓
    • D.Oscillates with growing amplitude

    Why: Static stability is the INITIAL tendency; dynamic stability describes the motion over time that follows.

  2. Q2. The primary contributor to longitudinal (pitch) stability is the:

    • A.Wing dihedral
    • B.Vertical fin
    • C.Horizontal stabilizer (tailplane)✓
    • D.Fuselage

    Why: The tailplane, acting far behind the CG, generates restoring pitching moments when AOA is disturbed.

  3. Q3. Moving the centre of gravity aft makes longitudinal stability:

    • A.Greater
    • B.Less✓
    • C.Unchanged
    • D.Neutral only at high speed

    Why: Aft CG reduces the static margin (CG to neutral point distance); the aft CG limit guarantees a minimum margin of stability.

  4. Q4. The main design feature providing lateral (roll) stability is:

    • A.Sweepback
    • B.Dihedral✓
    • C.A high fin
    • D.Anhedral

    Why: With dihedral, a sideslip towards the dropped wing puts that wing at a higher AOA, generating the lift to roll it back level.

  5. Q5. Dutch roll results from:

    • A.Strong directional stability compared with lateral stability
    • B.Strong lateral stability compared with directional stability✓
    • C.Neutral static stability in pitch
    • D.An aft CG

    Why: When the dihedral (lateral) effect dominates the fin's directional stability, a coupled roll-yaw oscillation develops — countered by a yaw damper.

  6. Q6. Spiral divergence is associated with:

    • A.Directional stability stronger than lateral stability✓
    • B.Lateral stability stronger than directional stability
    • C.Equal lateral and directional stability
    • D.Negative longitudinal stability

    Why: Strong directional vs weak lateral stability lets a disturbance develop into a slowly tightening descending spiral — slow enough to correct easily.