Weapon Propulsion and Architecture

1. Weapon Propulsion and Architecture Naval Weapons Systems

2. Learning Objectives • Comprehend gravity, impulse, and reaction propulsion • Comprehend factors involved in impulse propulsion (explosive propellant train, burn rate, interior ballistics) • Know the different types of reaction propulsion systems • Comprehend basic principles of fluid dynamics • Comprehend basic weapons architecture

3. Why is this important? • Evolution of Warfare • Fists, sticks, and stones • Spears and Bow/Arrow • 20th Century brought guns • Before fought in big formations (out mass enemy) • Machine guns and cannons • Increased need for dispersion • Grenades and explosive shells

4. 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.

5. Introduction • Every weapon requires some form of propulsion to deliver it to its intended target. • Propulsion systems are based on Newton’s Third Law: For every action there is an equal and opposite reaction.

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

7. 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 Propulsion

8. Gravity Bombs • MK-20 Rockeye • Free fall cluster bomb • Over 27,000 dropped during Desert stormTanks and armored vehicles • AGM-62 Walleye • Television guided glide bomb • 2000’ version “Fat Albert” • Used during Vietnam • MK-46 Torpedo

9. Impulse LaunchingChemical Reaction

10. 3 2 1 Igniter Primer Propellant Powder Impulse Propulsion • Projectile is ejected from a container by means of an initial impulse. • Explosive Propellant Train:

11. Propellants • Smokeless Powders or Gunpowder's: • All are designed to produce large volumes of gases at a controlled rate. • Rate is based on the maximum pressure that can be withstood by the gun barrel, casing, etc.

12. Burn Rate Controlling Factors- controls the pressure generated by the propellant • 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.

13. Burning Rates • The Burn Rate increases as both the pressure and temperature rise. • Classification by variation in burn rate: • Degressive: As it burns, the burning surface area decreases • Neutral: The burning surface area remains constant • Progressive: Burning surface area increases as it burns.

14. 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

15. Propulsion Propellent Burning Grains • Degressive burning Grains: • Ball Pellet Sheet • Strip Cord

16. Propulsion Propellent Burning Grains • Neutral Burning Grains: • Single Perforated • Star Perforated *

17. Propulsion Propellant Burning Grains • Progressive Burning Grains: • Multi-Perforated • Rosette

18. Reaction LaunchCompression of Liquids/Gasses

19. Propellants • Compressed Air / Gas: • Used to eject missiles or torpedoes from submarines. • Easily controllable; doesn't harm weapons • Problem: Compressor machinery to maintain a supply of compressed gas.

20. Liquid Fuels • More powerful than solid fuels • High volatility • Can’t be stored for long periods

21. 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 • Cruise Missiles • Turbo-jet, and Ram Jet engines

22. Pressure is Balanced Burning Propellant along the inside of the casing exerts pressure in all directions at once, until a nozzle is fitted a one end. Pressure is Un-Balanced Forward Velocity Thrust Reaction Propulsion • Development of Thrust in a Rocket Motor:

23. Bernoulli’s Theory Convergent Divergent Pressure Increases Velocity Decreases Pressure Decreases Velocity Increases

24. Gas Turbine Engine

25. Turbojet LM2500 DC 10

26. Turboprop

27. Low-Supersonic Mach 3 to Mach 5 JP-4 Ramjet

28. Scramjet Hydrogen Hypersonic Mach 5 to Mach 20

30. Advantages Simple Reliable Unlimited Speed Any medium/vacuum Few moving parts Full thrust at takeoff Store fully fueled Ready to fire! Disadvantages No booster Not restartable SOLID FUEL

31. Advantages Restartable Practically unlimited speed Any medium/vacuum Full thrust on take-off Less need for booster than air breather Staged with liquid/solid rockets Disadvantages Many moving parts Complex Cost and Safety issues More Volatile LIQUID FUEL

32. Advantages Large static thrust Oxygen from air Common fuels (JP-4,5,&8) Thrust independent of speed Disadvantages Basic design lacks improvements in efficiency and power TURBOJET

33. Advantages Quieter than turbojet More efficient at subsonic airspeeds than turbojet (typically at higher altitudes) Disadvantages More complex Large diameter engine More blades=more susceptible to FOD TURBOFAN

34. Advantages Very high fuel efficiency at slow speeds High shaft power to weight ratio Disadvantages Limited top speeds Noisy Complex prop driveshaft TURBOPROP

35. Advantages Simple No wearing parts Oxygen from air Lightweight Inexpensive to build and operate Common fuels Efficient at high speeds/altitudes Supersonic Hydrogen fuel (for SCRAMJET) Disadvantages In Developmental stages Cooling/Intake difficulties No thrust at rest Must be combined with another type of engine to get up to speed. Minimum Mach Number Hydrogen fuel (for SCRAMJET) EXPENSIVE fuel source RAMJET/SCRAMJET

36. Questions?