GATE Aerospace Engineering Flight Mechanics Syllabus

Flight Mechanics syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Flight Mechanics in GATE Aerospace Engineering, not a summary of it.

1. 1

   Atmosphere

   6 topics

   • Properties of Atmosphere
   • Standard Atmosphere
   • Classification of Aircraft
   • Airplane Configuration and Parts
     • Fixed Wing Aircraft
   • Flight Instruments
     • Altimeter
     • ASI (Air Speed Indicator)
     • VSI (Vertical Speed Indicator)
     • Turn-bank Indicator
   • Aerodynamic Concepts
     • Angle of Attack
     • Sideslip
     • Roll Control
     • Pitch Control
     • Yaw Control
     • Aerodynamic Forces
     • Aerodynamic Moments
2. 2

   Airplane Performance

   9 topics

   • Drag Polar
   • Take-off and Landing
   • Climb and Descent
     • Steady Climb
     • Steady Descent
   • Ceiling
     • Absolute Ceiling
     • Service Ceiling
   • Range and Endurance
   • Load Factor
   • Turning Flight
   • V-n Diagram
   • Winds
     • Headwinds
     • Tailwinds
     • Crosswinds
3. 3

   Static Stability

   5 topics

   • Stability and Control Derivatives
   • Longitudinal Stability
     • Stick Fixed Stability
     • Stick Free Stability
   • Horizontal Tail
     • Position
     • Size
   • Directional Stability
     • Vertical Tail Position
     • Vertical Tail Size
   • Lateral Stability
     • Wing Dihedral
     • Wing Sweep
     • Wing Position
     • Hinge Moments
     • Stick Forces
4. 4

   Special Topics

   6 topics

   • Dynamic Stability
   • Euler Angles
   • Equations of Motion
   • Decoupling of Dynamics
     • Longitudinal Dynamics
     • Lateral-Directional Dynamics
   • Longitudinal Modes
   • Lateral-Directional Modes

Flight Mechanics flashcards for GATE Aerospace Engineering

25 of 51 cards from the Flight Mechanics deck — real questions with worked answers.

1. What is the standard sea-level pressure, temperature, and density used in the International Standard Atmosphere (ISA)?

   Pressure $p_0 = 101325\ \text{Pa}$ (101.325 kPa), temperature $T_0 = 288.15\ \text{K}$ ($15^\circ\text{C}$), and density $\rho_0 = 1.225\ \text{kg/m}^3$.

2. In the ISA troposphere (0–11 km), what is the temperature lapse rate and the temperature variation with altitude?

   The lapse rate is $a = -6.5\ \text{K/km} = -0.0065\ \text{K/m}$, giving $T = T_0 + a\,h = 288.15 - 0.0065\,h$ (with $h$ in metres).

3. What characterizes the ISA stratosphere from 11 km to 20 km?

   It is isothermal: temperature is constant at $T = 216.65\ \text{K}$ ($-56.5^\circ\text{C}$), so pressure and density decay exponentially with altitude rather than as power laws.

4. State the hydrostatic equation that governs the variation of atmospheric pressure with altitude.

   $$\frac{dp}{dh} = -\rho g$$ where $\rho$ is air density and $g$ is gravitational acceleration; pressure decreases as altitude increases.

5. In a gradient (lapse-rate) layer of the standard atmosphere, how does pressure vary with temperature?

   $$\frac{p}{p_1} = \left(\frac{T}{T_1}\right)^{-\frac{g}{aR}}$$ and density follows $\dfrac{\rho}{\rho_1} = \left(\dfrac{T}{T_1}\right)^{-\left(\frac{g}{aR}+1\right)}$, where $a$ is the lapse rate and $R$ the gas constant.

6. In the isothermal layer of the standard atmosphere, how do pressure and density vary with altitude?

   $$\frac{p}{p_1} = \frac{\rho}{\rho_1} = \exp\!\left[-\frac{g\,(h-h_1)}{R\,T}\right]$$ an exponential decay since $T$ is constant.

7. What is the equation of state (ideal gas law) used for atmospheric air, and the value of the specific gas constant $R$?

   $$p = \rho R T$$ with $R = 287\ \text{J/(kg·K)}$ for air.

8. Distinguish between geometric altitude and geopotential altitude in atmosphere modelling.

   Geometric altitude is the true vertical distance above sea level; geopotential altitude assumes a constant $g$ (uses $g_0$) and is the value tabulated in standard-atmosphere relations. They are related via $h_{geopotential} = \dfrac{r\,h_{geometric}}{r + h_{geometric}}$, where $r$ is Earth's radius.

9. Define pressure altitude, density altitude, and temperature.

   Pressure altitude is the ISA altitude corresponding to the measured ambient pressure; density altitude is the ISA altitude corresponding to the measured ambient density. Density altitude strongly affects engine and aerodynamic performance.

10. How are aircraft broadly classified by their means of generating lift (lighter-than-air vs heavier-than-air)?

    Aircraft are classed as aerostats (lighter-than-air, e.g. balloons and airships, using buoyancy) and aerodynes (heavier-than-air, e.g. airplanes, gliders, helicopters, using aerodynamic lift).

11. How are heavier-than-air aircraft (aerodynes) subdivided?

    Into fixed-wing aircraft (airplanes, gliders), rotary-wing aircraft (helicopters, autogyros), and others such as ornithopters; lift comes from relative motion of wings/rotors through the air.

12. Name the major external parts of a fixed-wing airplane.

    Fuselage (body), wings, empennage (tail) comprising horizontal and vertical stabilizers, landing gear, and the powerplant/propulsion system.

13. What are the three primary control surfaces of a fixed-wing aircraft and the rotational axis each controls?

    Ailerons control roll (about the longitudinal axis), elevators control pitch (about the lateral axis), and the rudder controls yaw (about the vertical/normal axis).

14. Define the three body axes of an aircraft and the moments associated with them.

    Longitudinal (roll, $x$-axis, moment $L$), lateral (pitch, $y$-axis, moment $M$), and normal/vertical (yaw, $z$-axis, moment $N$). They intersect at the centre of gravity.

15. What is the function of flaps and slats as high-lift devices?

    They increase the wing's effective camber/area and maximum lift coefficient $C_{L,max}$ to allow lower stall and approach speeds; flaps are on the trailing edge, slats on the leading edge.

16. On what physical principle does the altimeter operate?

    It is an aneroid barometer that measures static (ambient) pressure and, using the standard-atmosphere pressure–altitude relation, displays altitude; pressure decreases with height so the instrument reads higher altitude for lower pressure.

17. What is the purpose of the Kollsman window (pressure setting) on an altimeter?

    It lets the pilot set the local sea-level reference pressure (e.g. QNH) so the altimeter reads correct altitude above mean sea level, correcting for non-standard surface pressure.

18. What does the Air Speed Indicator (ASI) measure, and from which pressure source?

    It measures dynamic pressure $q = p_{total} - p_{static}$ from the difference between pitot (total) and static pressures, displaying indicated airspeed (IAS).

19. Give the incompressible relation between dynamic pressure and airspeed used by the ASI.

    $$q = p_t - p_s = \tfrac{1}{2}\rho V^2 \quad\Rightarrow\quad V = \sqrt{\frac{2(p_t - p_s)}{\rho}}$$

20. Differentiate indicated, calibrated, equivalent, and true airspeed (IAS, CAS, EAS, TAS).

    IAS is raw ASI reading; CAS corrects for instrument/position error; EAS corrects CAS for compressibility; TAS corrects EAS for density via $V_{TAS} = V_{EAS}\sqrt{\rho_0/\rho}$. TAS exceeds IAS at altitude because density is lower.

21. What does the Vertical Speed Indicator (VSI) measure and how?

    It measures rate of climb or descent by sensing the rate of change of static pressure, using a calibrated leak (capillary/metering orifice) so the diaphragm responds to how fast static pressure changes; reading is in feet per minute (or m/s).

22. Why does a VSI exhibit lag, and what is instantaneous VSI (IVSI)?

    The calibrated leak takes time to equalize pressures, causing a few seconds' lag after a pitch change. An IVSI adds accelerometer-driven (dashpot) pumps that immediately respond to vertical acceleration, reducing lag.

23. What two pieces of information does the turn-and-bank (turn coordinator) indicator provide?

    The turn needle/aircraft symbol shows rate (and direction) of turn (driven by a gyroscope via precession), and the inclinometer ball shows whether the turn is coordinated (slip or skid).

24. In the turn-and-bank indicator, what do ball-to-the-inside and ball-to-the-outside indicate?

    Ball to the inside indicates a slip (too little rate of turn / too much bank, insufficient rudder); ball to the outside indicates a skid (too much rate of turn / too little bank, excess rudder). A centred ball means coordinated flight.

25. Define a standard-rate turn and the turn rate it corresponds to.

    A standard-rate (rate-one) turn is $3^\circ$ per second, completing a $360^\circ$ turn in 2 minutes; the turn coordinator's index marks are calibrated to it.

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