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Weapon Propulsion and Architecture

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Title: Weapon Propulsion and Architecture


1
Weapon Propulsion and Architecture
  • Naval Weapons Systems

2
Learning Objectives
  • Comprehend gravity, impulse, and reaction
    propulsion.
  • Comprehend the factors involved in impulse
    propulsion, including the explosive propellant
    train, the factors controlling burn rate, and
    interior ballistics.
  • Know the different types of reaction propulsion
    systems.

3
Learning Objectives
  • Comprehend the basic principles of fluid dynamics
    and be able to apply them in shipboard
    situations.
  • Know the concepts of lift and drag, atmospheric
    properties and effect, subsonic and supersonic
    flow characteristics, and high speed
    aerodynamics.
  • Know aerodynamic and hydrodynamic controls.
  • Comprehend basic weapons architecture.

4
Introduction
  • Every weapon requires some form of propulsion to
    deliver it to its intended target.
  • Propulsion systems are based on Newtons Third
    Law To every action there is an equal and
    opposite reaction.

5
I. Types of Propulsion
  • A) Propulsion Types can be divided into two
    categories
  • 1) Energy Source
  • Chemical Reaction
  • Compression of Liquids
  • Effect of Gravity
  • 2) Method of Launch
  • Impulse - a projectile
  • Reaction- a missile
  • Gravity - a bomb

6
B. Gravity Propulsion
7
C. Impulse Propulsion
  • Impulse propulsion systems include all weapons
    systems in which a projectile is ejected from a
    container by means of an initial impulse.
  • Explosive Propellant Train1) 2) 3)

Igniter
Primer
Propellant Powder
8
C.1 . Propellants(2 types)
  • a. Smokeless Powders or Gunpowders
  • Can be single or multi-based, depending on the
    number of components used to make it up. Powders
    are produced in a granular form.
  • All are designed to produce large volumes of
    gases at a controlled rate. This rate is based
    on the maximum pressure that can be withstood by
    the gun barrel, rocket casing, etc.

9
(a.1) Burn Rate Controlling FactorsThe burn
rate, which controls the pressure generated by
the propellant is controlled by variances in the
following factors
  • Size and shape of the powder grain
  • Web thickness amount of propellant between
    burning surfaces of the grain.
  • Chemical burn rate constant of the propellant
    material
  • Percentage of volatile material present.

10
(a.2) Burning Rates
  • The Burn Rate increases as both the pressure and
    temperature rise.
  • Propellants can also be classified by variations
    in their burning rates
  • Degressive As it burns, the burning surface area
    decreases
  • Neutral The burning surface area remains
    constant
  • Progressive Burning surface area increases as
    it burns.

11
Propulsion Propellent Burning Grains
  • Degressive burning Grains
  • Ball Pellet Sheet
  • Strip Cord

12
Propulsion Propellent Burning Grains
  • Neutral Burning Grains
  • Single Perforated
  • Star Perforated


13
Propulsion Propellant Burning Grains
  • Progressive Burning Grains
  • Multi-Perforated
  • Rosette

14
Propellants(2 types)
  • b. Compressed Air / Gas
  • Used to eject missiles or torpedoes from
    submarines.
  • Easily controllable doesn't harm weapons
  • However, requires loud compressor machinery to
    maintain a supply of compressed gas.

15
C.2. Interior Ballistics
  • Action Inside a Gun.
  • Ignited propellant creates pressure within the
    chamber that forces the projectile down the
    barrel.

Degressive
Neutral
Pressure
Progressive
Gun Barrel
16
D. Reaction Propulsion
  • Weapons employing reaction-type propulsion obtain
    thrust by creating a pressure differential in the
    medium they operate in, i.e. air or water.
  • Examples include
  • Rockets, Missiles
  • Turbo-jet, and Ram Jet engined Cruise Missiles

17
D.1. Development of Thrust in a Rocket Motor

Burning Propellant along the inside of the casing
exerts pressure in all directions at once, until
a nozzle is fitted a one end.
US weapons use solid fuel Russian Liquid- Loss of
subs
18
D.2. Types of Jets
  • Ramjet
  • Scramjet
  • Turbojet
  • Turbofan
  • Turboprop

19
Jets
D.2.a. Bernoullis Theory
Divergent
Convergent
Pressure lt Velocity gt
Pressure gt Velocity lt
20
D.2.b. Ramjet / Scramjet
Low-Supersonic Mach 3 to Mach 5
JP-4
Hydrogen
Hypersonic Mach 5 to Mach 20
21
D.2.c. Turbojet / Turbofan
22
D.2.d. Turboprop
23
II. Fluid dynamics
  • Aerodynamics The study of the motion of gaseous
    fluid flows, and of their actions against and
    around bodies in motion in that fluid.
  • There are four forces that act upon a missile in
    flight.
  • Thrust Due to the force from the engine
  • Weight Due to the force of gravity
  • Lift Due to the difference of air pressure
    above and below the airfoils, perpendicular to
    the direction of flight
  • Drag Due to the friction caused by air in front
    of and along the missile, opposes missile motion

24
Fluid dynamics
25
Fluid dynamics
  • Bernoulli's Principle Air flow on the top of an
    airfoil is faster than that on the bottom, thus
    the density of the air is less on the top of the
    airfoil, causing the missile to rise.

26
Fluid dynamics
  • Aerodynamic forces are greatly due to atmospheric
    properties.
  • Static pressure
  • Caused by the weight of the air upon an object
  • Static pressure decreases with an increase in
    altitude.
  • Density
  • Mass of air per unit volume
  • Density decreases with an increase in altitude.
  • Temperature Temperature decreases with an
    increase in altitude.
  • Humidity As humidity increases, air density
    decreases (less air molecules and more water
    molecules per unit volume).
  • Viscosity
  • Air's resistance to flow
  • Viscosity increases as temperature increases.

27
Fluid dynamics
  • Atmospheric conditions change with altitude,
    season, weather, location, and time of day.
  • Lift is directly related to the density of the
    air and the missile's velocity and angle of
    attack.
  • As static pressure decreases, lift decreases.
  • As density decreases, lift decreases.
  • As humidity increases, lift decreases.
  • As altitude increases, the combination of
    atmospheric effects reduces lift and the angle of
    attack must be adjusted.

28
Fluid dynamics
  • Drag is affected by atmospheric conditions.
  • As temperature increases, viscosity increases.
  • As viscosity increases, friction and drag
    increase.
  • At high speeds, the effects of aerodynamic forces
    and atmospheric forces are amplified.
  • Subsonic and supersonic flow characteristics
  • At supersonic speeds, air is compressed and the
    density of the air changes.
  • At subsonic speeds, density changes are minimal
    and can be ignored. As area decreases, velocity
    increases.

29
Fluid dynamics
  • Hydrodynamics The study of the motion of
    fluids, and of their actions against and around
    bodies in motion in that fluid.
  • Air and water are both fluids and act similarly.
  • There are differences due to differences in
    density and mass, and the lack of compressibility
    of water.
  • Torpedoes, like missiles, are affected by lift
    and drag, and pitch, roll, and yaw.
  • Torpedoes, unlike missiles, are affected by
    buoyancy.

30
III. Control surfaces
  • Missiles
  • Canard control
  • Small control surfaces are forward.
  • Lifting surfaces are aft.
  • Wing control
  • Control surfaces are near the center of the
    airframe.
  • Control surfaces also provide lift.
  • Tail control
  • Control surfaces are aft.
  • Lift surfaces are near the center of the airframe.

31
Control surfaces
  • Torpedoes
  • Upper and lower fins control roll and pitch.
  • Port and starboard fins control pitch.

32
IV. Basic missile architecture
  • Guidance system
  • Warhead and fuze
  • Autopilot
  • Propulsion system
  • Control surfaces

33
Basic torpedo architecture
  • Propulsion system
  • Control and guidance system
  • Warhead and fuze

34
Gun ammunition architecture
  • Penetrating

35
Gun ammunition architecture
Gun ammunition architecture
  • Penetrating
  • Fragmentation

36
Gun ammunition architecture
  • Penetrating
  • Fragmentation
  • Special purpose

37
Assignment 12
  • Workbook
  • Ch. 16 2,4,5,12,13,14,15
  • Describe how thrust in a rocket motor is
    developed
  • Descibe how a subsonic nozzel works.
  • What are the 4 forces acting on a missile during
    flight?
  • Read Ch. 17 Launching Systems
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