Weapon Propulsion and Weapon Propulsion and ArchitectureArchitecture

Naval Weapons SystemsNaval Weapons Systems

Learning ObjectivesLearning Objectives

Comprehend gravity, impulse, and Comprehend gravity, impulse, and reaction propulsionreaction propulsionComprehend factors involved in impulse Comprehend factors involved in impulse propulsion (explosive propellant train, burn propulsion (explosive propellant train, burn rate, interior ballistics)rate, interior ballistics)Know the different types of reaction Know the different types of reaction propulsion systemspropulsion systemsComprehend basic principles of fluid Comprehend basic principles of fluid dynamicsdynamicsComprehend basic weapons architectureComprehend basic weapons architecture

Why is this important?Why is this important?

Evolution of WarfareEvolution of Warfare– Fists, sticks, and stonesFists, sticks, and stones– Spears and Bow/ArrowSpears and Bow/Arrow– 2020thth Century brought guns Century brought guns

Before fought in big formations (out mass enemy)Before fought in big formations (out mass enemy)

– Machine guns and cannonsMachine guns and cannonsIncreased need for dispersionIncreased need for dispersion

– Grenades and explosive shellsGrenades and explosive shells

In Desert Storm the allies decimated the Iraqi ranks and infrastructure from the air and sea before the troops ever entered the scene. When troops did move in, the Iraqi's were confused, hungry and demoralized. Many surrendered and those few that didn't were quickly killed.

IntroductionIntroduction

Every weapon requires some form of Every weapon requires some form of propulsion to deliver it to its intended propulsion to deliver it to its intended target.target.

Propulsion systems are based on Propulsion systems are based on Newton’s Third Law: Newton’s Third Law: For every action For every action there is an equal and opposite reaction.there is an equal and opposite reaction.

Types of PropulsionTypes of Propulsion

Propulsion Types can be divided into two Propulsion Types can be divided into two categories:categories:– 1) Energy Source1) Energy Source

Compression of Liquids/GassesCompression of Liquids/GassesChemical ReactionChemical ReactionEffect of GravityEffect of Gravity

– 2) Method of Launch2) Method of LaunchGravity - a bombGravity - a bombImpulse - a projectileImpulse - a projectileReaction - a missileReaction - a missile

Gravity PropulsionGravity Propulsion

Simple: Uses the force of gravity to get the weapon to the target.

Used in: - All free fall and glide bombs - Torpedoes launched from aircraft (until it submerges)

Gravity BombsGravity Bombs

MK-20 RockeyeMK-20 Rockeye– Free fall cluster bombFree fall cluster bomb– Over 27,000 dropped during Over 27,000 dropped during Desert stormTanks and Desert stormTanks and armored vehiclesarmored vehicles

AGM-62 WalleyeAGM-62 Walleye– Television guided glide bombTelevision guided glide bomb– 2000’ version “Fat Albert”2000’ version “Fat Albert”– Used during VietnamUsed during Vietnam

MK-46 TorpedoMK-46 Torpedo

Impulse LaunchingImpulse LaunchingChemical ReactionChemical Reaction

Impulse PropulsionImpulse Propulsion

Projectile is ejected from a container by Projectile is ejected from a container by means of an initial impulse.means of an initial impulse.

Explosive Propellant Train:Explosive Propellant Train:

PrimerPrimer

1

IgniterIgniter

2

Propellant PowderPropellant Powder

3

PropellantsPropellants

Smokeless Powders or Gunpowder's:Smokeless Powders or Gunpowder's:

– All are designed to produce large volumes All are designed to produce large volumes of gases at a controlled rate. of gases at a controlled rate.

– Rate is based on the maximum pressure Rate is based on the maximum pressure that can be withstood by the gun barrel, that can be withstood by the gun barrel, casing, etc.casing, etc.

Burn Rate Controlling FactorsBurn Rate Controlling Factors- - controls the pressure generated by controls the pressure generated by

the propellantthe propellant

Size and shape of the powder grainSize and shape of the powder grain

Web thickness; amount of propellant Web thickness; amount of propellant between burning surfaces of the grain.between burning surfaces of the grain.

Chemical burn rate constant of the Chemical burn rate constant of the propellant materialpropellant material

Percentage of volatile material present.Percentage of volatile material present.

Burning RatesBurning Rates

The Burn Rate increases as both the The Burn Rate increases as both the pressure and temperature rise.pressure and temperature rise.Classification by variation in burn rate:Classification by variation in burn rate:– DegressiveDegressive: As it burns, the burning surface area : As it burns, the burning surface area

decreasesdecreases– NeutralNeutral:: The burning surface area remains The burning surface area remains

constantconstant– ProgressiveProgressive: Burning surface area increases as : Burning surface area increases as

it burns.it burns.

Interior BallisticsInterior Ballistics

Action Inside a Gun.Action Inside a Gun.– Ignited propellant creates pressure within the Ignited propellant creates pressure within the

chamber that forces the projectile down the chamber that forces the projectile down the barrel.barrel.

Gun BarrelGun Barrel

ProgressiveProgressive

NeutralNeutralDegressiveDegressive

PressurePressure

Propulsion Propellent Burning GrainsPropulsion Propellent Burning Grains

Degressive burning Grains: Degressive burning Grains:

BallBall PelletPellet SheetSheet

– StripStrip CordCord

Propulsion Propellent Burning GrainsPropulsion Propellent Burning Grains

Neutral Burning Grains:Neutral Burning Grains:– Single PerforatedSingle Perforated

– Star PerforatedStar Perforated

**

Propulsion Propellant Burning GrainsPropulsion Propellant Burning Grains

Progressive Burning Grains:Progressive Burning Grains:– Multi-PerforatedMulti-Perforated

– RosetteRosette

Reaction LaunchReaction LaunchCompression of Compression of Liquids/GassesLiquids/Gasses

PropellantsPropellants

Compressed Air / Gas:Compressed Air / Gas:– Used to eject missiles or torpedoes from Used to eject missiles or torpedoes from

submarines.submarines.– Easily controllable; doesn't harm weaponsEasily controllable; doesn't harm weapons– Problem: Problem: Compressor machinery to maintain Compressor machinery to maintain

a supply of compressed gas.a supply of compressed gas.

Liquid FuelsLiquid Fuels

More powerful than solid fuelsMore powerful than solid fuels

High volatilityHigh volatility

Can’t be stored for long periodsCan’t be stored for long periods

Reaction PropulsionReaction Propulsion

Weapons employing reaction-type Weapons employing reaction-type propulsion obtain thrust by creating a propulsion obtain thrust by creating a pressure differential in the medium they pressure differential in the medium they operate in, i.e. air or water.operate in, i.e. air or water.

Examples include:Examples include:– Rockets, MissilesRockets, Missiles– Cruise MissilesCruise Missiles– Turbo-jet, and Ram Jet enginesTurbo-jet, and Ram Jet engines

Reaction PropulsionReaction Propulsion

Development of Thrust in a Rocket Development of Thrust in a Rocket Motor:Motor:

Pressure is BalancedPressure is Balanced Burning Propellant along the insideBurning Propellant along the insideof the casing exerts pressure in allof the casing exerts pressure in alldirections at once, until a nozzle isdirections at once, until a nozzle isfitted a one end.fitted a one end.

Pressure is Un-BalancedPressure is Un-BalancedForward VelocityForward Velocity

ThrustThrust

Bernoulli’s TheoryBernoulli’s Theory

ConvergentConvergent DivergentDivergent

Pressure IncreasesPressure IncreasesVelocity DecreasesVelocity Decreases

Pressure DecreasesPressure DecreasesVelocity IncreasesVelocity Increases

Gas Turbine EngineGas Turbine Engine

TurbojetTurbojet

LM2500LM2500

DC 10DC 10

TurbopropTurboprop

RamjetRamjet

Low-Supersonic Mach 3 to Mach 5Low-Supersonic Mach 3 to Mach 5

JP-4JP-4

ScramjetScramjet

Hypersonic Mach 5 to Mach 20Hypersonic Mach 5 to Mach 20

HydrogenHydrogen

SOLID FUELSOLID FUEL

AdvantagesAdvantages– SimpleSimple– ReliableReliable– Unlimited SpeedUnlimited Speed– Any medium/vacuumAny medium/vacuum– Few moving partsFew moving parts– Full thrust at takeoffFull thrust at takeoff– Store fully fueledStore fully fueled– Ready to fire!Ready to fire!

DisadvantagesDisadvantages– No boosterNo booster– Not restartableNot restartable

LIQUID FUELLIQUID FUEL

AdvantagesAdvantages– RestartableRestartable– Practically unlimited Practically unlimited

speedspeed– Any medium/vacuumAny medium/vacuum– Full thrust on take-offFull thrust on take-off– Less need for booster Less need for booster

than air breatherthan air breather– Staged with liquid/solid Staged with liquid/solid

rocketsrockets

DisadvantagesDisadvantages– Many moving partsMany moving parts– ComplexComplex– Cost and Safety Cost and Safety

issuesissues– More VolatileMore Volatile

TURBOJETTURBOJET

AdvantagesAdvantages– Large static thrustLarge static thrust– Oxygen from airOxygen from air– Common fuels (JP-Common fuels (JP-

4,5,&8)4,5,&8)– Thrust independent of Thrust independent of

speedspeed

DisadvantagesDisadvantages– Basic design lacks Basic design lacks

improvements in improvements in efficiency and powerefficiency and power

TURBOFANTURBOFAN

AdvantagesAdvantages– Quieter than turbojetQuieter than turbojet– More efficient at More efficient at

subsonic airspeeds subsonic airspeeds than turbojet (typically than turbojet (typically at higher altitudes)at higher altitudes)

DisadvantagesDisadvantages– More complexMore complex– Large diameter engineLarge diameter engine– More blades=more More blades=more

susceptible to FODsusceptible to FOD

TURBOPROPTURBOPROP

AdvantagesAdvantages– Very high fuel Very high fuel

efficiency at slow efficiency at slow speedsspeeds

– High shaft power to High shaft power to weight ratioweight ratio

DisadvantagesDisadvantages– Limited top speedsLimited top speeds– NoisyNoisy– Complex prop Complex prop

driveshaftdriveshaft

RAMJET/SCRAMJETRAMJET/SCRAMJET

AdvantagesAdvantages– SimpleSimple– No wearing partsNo wearing parts– Oxygen from airOxygen from air– LightweightLightweight– Inexpensive to build and Inexpensive to build and

operateoperate– Common fuelsCommon fuels– Efficient at high Efficient at high

speeds/altitudesspeeds/altitudes– SupersonicSupersonic– Hydrogen fuel (for Hydrogen fuel (for

SCRAMJET)SCRAMJET)

DisadvantagesDisadvantages– In Developmental stagesIn Developmental stages– Cooling/Intake difficultiesCooling/Intake difficulties– No thrust at restNo thrust at rest– Must be combined with Must be combined with

another type of engine to another type of engine to get up to speed.get up to speed.

– Minimum Mach NumberMinimum Mach Number– Hydrogen fuel (for Hydrogen fuel (for

SCRAMJET)SCRAMJET)– EXPENSIVE fuel sourceEXPENSIVE fuel source

Questions?Questions?