Question Bank Rockets and missiles

JEPPIAAR ENGINEERING COLLEGE DEPARTMENT OF AERONAUTICAL ENGINEERING ANNA ANN A UNIVERSI UNIVERSITY TY QUE QUESTIO STION N BANK BANK AE2033 AE2 033 ROC ROCKET KET AND MIS MISSILE SILE

PART A MAY/JUNE 2013 1.Explain homogeneous gravitational field

In a homogeneous gravitational field, the field strength ‘g’ is assumed to be constant. If we consider the earth locally as being flat, the local gravitational field may be considered homogeneous. Actually the earth is nearly spherical and its gravitational field can be approximated very well by a central inverse square field. As long as the altitude and range are small relative to the mean earth’s radius, the earth may be considered flat and the field strength can approximated very well by a constant. 2.What is the effect of assuming that flight is in vacuum.

The motion of rocket in the absence of the gravitational and aerodynamics forces. 3.What is rocket dispersion

If the rocket deviate from its original nominal trajectory then it is called as rocket dispersion dispersion 4.What are the method of stage separation

Stage separation in atmosphere Firing in the hole technique. Helical compression spring technique Stage separation in space Ullage rocket 5.What is base pressure

The pressure exerted on the base or extreme aft end of a body, as of a cylindrical or boat-tailed body or of a blunt-trailing-edge wing in fluid flow. 6.What is fineness ratio

Fineness ratio is a term used in naval architecture and aerospace engineering to describe the

overall shape of a streamlined body. Specifically, it is the ratio of the length of a body to its maximum width; shapes that are "short and fat" have a low fineness ratio, those that are "long and skinny" have high fineness ratios. 7. What is meant by propellant hammer

Propellant hammer is nothing but the pressure surging present in the liquid propellant feed line. Basically the feed line walls are very thin, on sudden closure of valves; a pressure pulse is generated at the neighborhood of valve. It travels back to the tank at some velocity and keeps the liquid static pressure increasing.

8.Draw the sketch of pyrogen igniter

9.Specify the location of rocket where extremely high temperature will occur.

Nose cone, combustion chamber and nozzle. 10.How to eliminate geysering effect

NOV/DEC 2013 1.Define total thrust and specific thrust of a rocket unit.

The total thrust is the total force produced by a rocket propulsion system acting upon a vehicle. Specific thrust is a ratio of thrust to the mass flow rate of propellant. 2.Write short notes on ignition process of liquid propellant

Ignition can be performed in many ways, but perhaps more so with liquid propellants than other rockets a consistent and significant ignitions source is required; a delay of ignition (in some cases as small as) a few tens of milliseconds can cause overpressure of the chamber due to excess propellant. A hard start can even cause an engine to explode. Generally, ignition systems try to apply flames across the injector surface, with a mass flow of approximately 1% of the full mass flow of the chamber. Safety interlocks are sometimes used to ensure the presence of an ignition source before the main valves open; however reliability of the interlocks can in some cases be lower than the ignition system. Thus it depends on whether the system must fail safe, or whether overall mission success is more important. Interlocks are rarely used for upper, unmanned stages where failure of the interlock would cause loss of mission, but are present on the SSME, to shut the engines down prior to liftoff of the Space Shuttle. In addition, detection of successful ignition of the igniter is surprisingly difficult, some systems use thin wires that are cut by the flames, pressure sensors have also seen some use. Methods of ignition include pyrotechnic, electrical (spark or hot wire), and chemical. Hypergolic propellants have the advantage of self igniting, reliably and with less chance of hard starts. In the 1940s, the Russians began to start engines with hypergolic fuel, then switch over to the primary propellants after ignition. This was also used on the American F-1 rocket engine on the Apollo program. 3.Mention the types of the aerodynamics forces and moment on a missile

Lift, drag, weight and thrust---------aerodynamic forces Pitching moment , yawing moment and rolling moment----------moment

4.Write the rocket principle and rocket equation Newton's First Law

Newton's first law can be stated as: An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force. Newton's Second Law

This law of motion is essentially a statement of a mathematical equation. The three parts of the equation are mass (m), acceleration (a), and force (f). Using letters to symbolize each part, the equation can be written as follows: F = ma

Let's apply this principle to a rocket. The pressure created by the controlled explosion taking place inside the rocket's engines is a force called thrust. That pressure accelerates the gas one way and the rocket the other. Newton's Third Law

Newton's third law can be stated as: Every action has an equal and opposite reaction. If you have ever stepped off a small boat that has not been properly tied to a pier, you will know exactly what this law means. The boat goes forward, you go backward! Rocket thrust equation

Ideal rocket equation

5.Write at least four performance parameters of rocket

In using values of thrust, specific impulse, propellant flow, and other performance parameters, one must be careful to specify or qualify the conditions under which a specific number is presented. There are at least four sets of performance parameters and they are often

quite different in concept and value, even when referring to the same rocket propulsion system. Each performance parameter, such as F, Is, c, ~U 2 and/or rh, should be accompanied by a clear definition of the conditions under which it applies, namely: a. Chamber pressure; also, for slender chambers, the location where this pressure prevails (e.g., at nozzle entrance). b. Ambient pressure or altitude or space (vacuum). c. Nozzle expansion area ratio and whether this is an optimum. d. Nozzle shape and exit angle (see Table 3-3). e. Propellants, their composition or mixture ratio. f. Key assumptions and corrections made in the calculations of the theoretical performance g. Initial temperature of propellants.

6.What is escape velocity? Write the equation for escape velocity

In physics, escape velocity is the speed at which the kinetic energy plus the gravitational potential energy of an object is zero. It is the speed needed to "break free" from the gravitational attraction of a massive body, without further propulsion. For a spherically symmetric body, the escape velocity at a given distance is calculated by the formula[1]

where G is the universal gravitational constant (G = 6.67×10−11 m3 kg−1 s−2), M the mass of the planet, star or other body, and r the distance from the center of gravity

7.What is the need for rocket staging

Multistage rockets allow improved payload capability for vehicles with a high V requirement such as launch vehicles or interplanetary spacecraft. In a multistage rocket, propellant is stored in smaller, separate tanks rather than a larger single tank as in a single-stage rocket. Since each tank is discarded when empty, energy is not expended to accelerate the empty tanks, so a higher total V is obtained. Alternatively, a larger payload mass can be accelerated to the same total V. For convenience, the separate tanks are usually bundled with their own engines, with each discardable unit called a stage. 1. Stages with higher Isp should be above stages with lower Isp. 2. More V should be provided by the stages with the higher Isp. 3. Each succeeding stage should be smaller than its predecessor. 4. Similar stages should provide the same V.

8.How are rocket classified?

Solid propellant rocket Liquid propellant rocket Hybrid rocket 9.What are the methods available to find the rocket vector control

Jetavatar Gimbal engine SITVC Jet control 10.Write short notes on material properties which are used in rockets and missiles

Material should with stand high temperature Material have less weight

PART B MAY/JUNE2013 1. Derive an expression for rocket motion in homogenous gravitation field with constant pitch angle.

Refer rocket propulsion and space dynamics book by cornelisse page no: 250-254 2. Derive an expression for burnout range of a rocket motion in vacuum.

Refer rocket propulsion and space dynamics book by cornelisse page no: 242-246

3.Explain various method of thrust vector control. Explain with neat sketches.

Refer rocket propulsion by sutton page no:608-612 Or Refer hardcopy notes unit -IV page no: 2-7

4.Derive the expression for the culmination altitude of a two stage rocket .Explain all assumption clearly.

Refer rocket propulsion and space dynamics book by cornelisse page no: 250-254 5.Explain the lateral aerodynamics force and lateral damping forces.

Refer hardcopy notes unit -2 page no: 34-38

6. Discuss the design feature of wing, canard and tail control qualitatively.

Refer hardcopy notes unit- 4 page no: 31-34

7.Expalin with neat sketches i) upwash

Refer hardcopy notes unit -2 page no: 44-45 ii) Downwash

Refer hardcopy notes unit -2page no: 45 iii) Longitudinal stability of rocket

Refer rocket propulsion and space dynamics book by cornelisse page no:325-326 iv) classification of missile


8. Explain with neat sketches about turbine feed system


9. Explain combustion system of solid rocket motor


10. What is the igniter design consideration? Explain

Refer hardcopy notes unit -1 page no: 14-15 11. Explain about different types of injector with neat sketches


12. what are the special requirements of materials to perform under adverse pressure consideration


13. Discuss about various propellant tank design used for rockets with neat sketches.


NOV/DEC 2013 1. Explain the physical and chemical process of solid propellants combustion


2. Explain with neat diagram the two liquid propellant feed system?


3.Explain the use of rocket engines for maneuvering orbit adjustment or altitude control

Refer Rocket propulsion by Sutton book page no: 228-230

4. What are the desirable liquid propellant properties?

Refer Rocket propulsion by Sutton book page no:248-251

5.Derive the basic equation of rocket with neat diagram

Refer hardcopy notes unit -3 page no:2-5

6.Explain the forces action on a vehicle in the atmosphere w.r.t gravity free, drag free flight

Refer Rocket propulsion by Sutton book page no: 102-106

7. Explain the concept of lateral damping moment and longitudinal damping moment of rocket.

Refer hardcopy notes unit -2 page no:34-36&39-40

8. Explain clearly with neat diagram of staging and clustering of rockets? Hint : parallel staging and serial staging

9. Explain the following freely falling bodies of rockets:

i) orbital or sub orbital flights ii) State of weightlessness under free fall Refer hardcopy notes 10. Explain with neat diagrams any four four rocket jet control method.


11.What is vehicle optimization? Explain the optimization techniques in rockets and missile with neat diagram.


12. Mention any eight components of rockets. Suggest and justify the materials for these components


13.Give any two examples of adverse condition faced by aerospace materials with sketches . Explain hoe materials system can be designed to perform under these adverse conditions.


Question Bank Rockets and missiles

Recommend Documents