GATE 2014 Aerospace Engineering Syllabus – Flight Mechanics

Flight Mechanics

Atmosphere

  • Properties,
  • Standard atmosphere,
  • Classification of aircraft,
  • Airplane configurations and various parts

Airplane Performance

  • Pressure Altitude;
  • Equivalent, calibrated, indicated air speeds;
  • Primary flight instruments: Altimeter, ASI, VSI, Turn-bank indicator,
  • Drag polar;
  • Takeoff and landing;
  • Steady climb & descent;
  • Absolute and service ceiling;
  • Cruise, climb, endurance or loiter;
  • Load factor,
  • Turning flight,
  • V-n diagram;
  • Winds: head, tail & cross winds.

Static Stability

  • Angle of attack,
  • Sideslip;
  • Roll, pitch &yaw control;
  • Longitudinal stick fixed & free stability,
  • Horizontal tail position and size;
  • Directional stability,
  • Vertical tail position and size;
  • Dihedral stability.
  • Wing dihedral, sweep position; hinge movements, stick forces.

Dynamic Stability

  • Euler angles;
  • Equations of motion;
  • Aerodynamic forces and moments,
  • Stability & control derivatives;
  • Decoupling of longitudinal and lateral directional dynamics;
  • Longitudinal and lateral directional modes.

GATE 2014 Aerospace Engineering Syllabus – Mathematics

Engineering Mathematics

Linear Algebra

  • Matrix algebra,
  • Systems of linear equation,
  • eigen values and eigen vectors.

Calculus

  • Functions of single variable, limit, continuity and differentiability,
  • Mean value theorems,
  • Evaluation of definite and improper integral,
  • Partial derivatives,
  • Total derivatives,
  • Maxima and minima,
  • Gradient, divergence and curl,
  • Vector identities,
  • Directional derivatives, line, surface and volume integrals,
  • Theorems of Stokes, Gauss and Green.

Differential calculus

  • Frist order linear and nonlinear equations,
  • Higher order linear ODEs with constant coefficients,
  • Cauchy and Euler equations,
  • Initial and boundary value problems,
  • Laplace transforms.
  • Partial differential equations and separation of variables methods.

Numerical Methods

  • Numerical solution of linear and nonlinear algebraic equations,
  • Integration by trapezoidal and Simpson rule,
  • Single and Multi-step methods for differential equations.

Nikolaus Otto’s four stroke engine process

Nikolaus Otto was born in Holzhausen, Germany on 10th June 1832. In his early years he began experimenting with gas engines and completed his first atmospheric engine in 1867. In 1872 he joined with Gottlieb Daimler and Wilhelm Maybach and in 1876 developed the first 4-stroke cycle internal combustion engine based on principles patented in 1862 by Alphonse Beau de Rochas. Although Otto’s patent claim for the’Otto Cycle’ was invalidated in 1886, his engineering work led to the first practical use of the 4stroke cycle which was to provide the driving force for transportation for over a century. Nikolaus Otto died on 26th January 1891.

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Induction Stroke
The induction stroke is generally considered to be the first stroke of the Otto 4-Stroke Cycle. At this point in the cycle, the inlet valve is open and the exhaust valve is closed. As the piston travels down the cylinder, a new charge of fuel/air mixture is drawn through the inlet port into the cylinder. The adjacent figure shows the engine crankshaft rotating in a clockwise direction. Fuel is injected through a sequentially controlled port injector just behind the inlet valve.
From a theoretical perspective, each of the strokes in the cycle complete at Top DeadCentre (TDC) or Bottom Dead Centre (BDC), but
in practicality, in order to overcome mechanical valve delays and the inertia of the new fuel/air
mixture, and to take advantage of the momentum of the exhaust gases, each of the strokes invariably begin and end outside the 0,180, 360, 540 and 720 (0) degree crank positions
see the Otto valve timing chart

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Compression Stroke
The compression stroke begins as the inlet valve closes and the piston is driven upwards in the
cylinder bore by the momentum of the crankshaft and flywheel.
Compression in a spark ignition engine is used to force the oxygen and hydrocarbon molecules of the fuel/air mixture into close proximity with each other. This not only raises the temperature
significantly (the work of compression is converted into heat), but the action transforms
the mixture from something that is extremely difficult to ignite under normal atmospheric conditions into something that will burn rapidly after being ignited with just a spark Unfortunately, with lower (unleaded) octane fuels and high compression ratios, it is possible
to generate sufficient heat during compression for the mixture to auto-ignite, thereby effectively limiting the practical volumetric
efficiency of the Otto cycle.

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Spark Ignition
Spark ignition is the point at which the spark is generated at the sparking plug and is an essential difference between the Otto and Diesel cycles. It may also be considered as the beginning of the power stroke. It is shown here
to illustrate that due to flame propagation delays, spark ignition timing commonly takes place 10 degress before TDC during idle and will advance to some 30 or so degrees under normal running conditions.

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Power Stroke
The power stroke begins as the fuel/air mixture is ignited by the spark. The rapidly burning mixture attempting to expand within the cylinder walls, generates a high pressure which
forces the piston down the cylinder bore. The linear motion of the piston is converted into
rotary motion through the crankshaft. The rotational energy is imparted as momentum to the flywheel which not only provides power for the end use, but also overcomes the work of compression and mechanical losses incurred in the cycle (valve opening and closing, alternator,
fuel pump, water pump, etc.).

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Exhaust Stroke
The exhaust stroke is as critical to the smooth and efficient operation of the engine as that of
induction. As the name suggests, it’s the stroke during which the gases formed during combustion are ejected from the cylinder. This
needs to be as complete a process as possible, as any remaining gases displace an equivalent
volume of the new charge of fuel/air mixture and leads to a reduction in the maximum
possible power.Tuned exhaust manifolds help to maintain the
momentum of the gas during the stroke to assist in the removal of the exhaust gases. They can
also be tuned within the maximum power rev range to create reflections or standing waves at the exhaust port to prevent some of the new fuel/air mixture from disappearing through the exhaust port during valve overlap (see below).

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Exhaust and Inlet Valve Overlap
Exhaust and inlet valve overlap is the transition between the exhaust and inlet strokes and is a
practical necessity for the efficient running of any internal combustion engine. Given the
constraints imposed by the operation of mechanical valves and the inertia of the air in the inlet manifold, it is necessary to begin opening the inlet valve before the piston reaches
Top Dead Centre (TDC) on the exhaust stroke. Likewise, in order to effectively remove all of the combustion gases, the exhaust valve remains open until after TDC. Thus, there is a point in each full cycle when both exhaust and
inlet valves are open. The number of degrees over which this occurs and the proportional split across TDC is very much dependent on the engine design and the speed at which it operates.

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source:www.kruse-ltc.com

Comet ISON ( C/2012 S1 )

Img Source: Wikipedia
Img Source: Wikipedia

C/2012 S1 AKA Comet ISON or Comet Nevski-Novichonok, is a latest comet discovered and confirmed on Sep 21 2012 by two Russian astronomers Vitali Nevski and Artyom Novichonok.  The discovery made using the 0.4 reflector of the International Scientific Optical Network near Kislovodsk, Russia and the Automated asteroid program CoLiTec.

It was actually on 28 Dec 2011 by Mount Lemmon Survey and by Pan-STARRS from 28 Jan 2012 were quickly located. Later on after the discovery some observations are made by SWFIT and suggests that the comet’s nucleus is around 5 kilometers (3.1 miles) in diameter.

Now let’s talk about it’s orbit. This comet is coming from the Oort cloud which is beyond the Kuiper belt surrounding our solar system outside Pluto’s orbit. It will come to the perihelion ( which is the closest point to the sun in it’s orbit ) on 28 Nov 2013 at a distance of 0.0124 AU (18, 60,000 km) from the centre point of the sun, which makes it 11,65,000 km from the surface of the sun. The trajectory is found to be hyperbolic, which means this comet never came before and will never come again. It has passed the Mars at a distance of 0.07248 AU on Oct 1 2013 and it also been captured by the Mars Reconnaissance orbiter (MRO). It has been given below. It will pass near Earth on Dec 26 2013 at a distance of 0.4292 AU (6,42,10,000 km).

ison-montage-jpg
Img Source : uahirise.org

Are you asking will it visible on earth….???

The answer is yes. Initially it is predicted to reach an apparent magnitude greater then full moon, but later observations predicted that it only will reach a magnitude just greater than Venus. However it will be only visible to the naked eye from the first week of the Nov 2013. It will get brighter and brighter when it closes on Sun and it will be visible even after it survives the perihelion until the first week of Jan 2014.

There is debate going on on whether the comet will survive it’s closest approach to the Sun or it will disintegrated by our Sun’s immense gravitational field. Because there is something called “Roche limit”, it will determine the comet’s survival. We will see about Roche limit about later

Img Source : Wikipedia
Img Source : Wikipedia

The above image is the prediction of the trajectory of the comet ISON. Hubble’s capture of ISON near Jupiter orbit, it is given below

IMG Source : Wikipedia
IMG Source : Wikipedia

Our site will post further updates and images captured us using our telescope………

Please Stay Tuned………….