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Final Proposal: Enhanced Counter Air Projectile (ECAP) IPT 3 Submitted By: Progressive Ammunition April 22, 2004

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Crew Escape Mission Contest

Final Proposal:Enhanced Counter Air Projectile

(ECAP)

IPT 3

Submitted By:

Progressive Ammunition

r

April 22, 2004

Submitted To:

Dr. Robert A. Frederick, Jr.

Associate Professor

Technology Hall N231

Department of Mechanical and Aerospace Engineering

University of Alabama in Huntsville

Huntsville, AL 35899

[email protected]

Class Web Page: http://www.eb.uah.edu/ipt/

r

Contributors

Project Office:

Wesley Gladden

Systems Engineering

Michael Ray, Wayna Esquibel, Byron Phillips

Seekers and Guidance

Michael Youngblood

Control

Stuart Johnson, Tracey Smith

Navigation and Power

Eulice Chapman

Modeling and Simulation

Amanda Brewer, Cheryl Steely

Advanced Analysis

ESTACA (Clement Ducasse, Romain Monery)

Launch Platform/ Prototyping

Ruben Hall, Terry Lingenfelter

Industrial Mentors

Participating Agencies

U.S. Army Aviation and Missile research, Development and Engineering Center

The University of Alabama in Huntsville

General Dynamics Armament and Technical Products

Ecole Superieure des Techniques Aeronautiques et de Construction

Sigma Services of America

ONERA

The University of Alabama in Huntsville

April 22, 2004

Executive Summary [T. Smith]

English

The following report provides detailed information about the design and development of the Super Moth ECAP system by Progressive Ammunition. The report not only identifies the process and technical aspects of the ECAP system, the need for the product, manufacturing considerations, and future development issues. The first section of the report deals with the need for the ECAP system and the requirements that must be met as laid out by the customer. The main purpose of the system is to protect U.S. military troops from incoming projectile attacks, by destroying the threat before it can cause damage. The technical aspects of this system are laid out in the second part of the report. This section includes information on guidance, control, sensors, power, structural analysis, and launch platforms. The guidance system employs a dynamic control algorithm to provide output to the control system. The control system consists of a set of thrusters powered by solid rocket propellant, which apply up to 38 N of force. A CAP-12087 thermal battery powers the bullet and the launch platform is the MK3. This section also includes analysis performed using simulations in both six and three degrees of freedom. The main points of each of these systems and how they interact are given, but more specific information can be found in the appendices of the report. The final section of the report addresses manufacturing processes, summary of the technical information, and also lays out Progressive Ammunitions recommendations and plans for future development of the Super Moth ECAP system.

French [ESTACA]

Le rapport suivant fournit l'information dtaille de la conception et le dveloppement du systme de ECAP de Papillon Super par les Munitions Progressives. Le rapport identifie non seulement le procd et les aspects techniques du systme de ECAP, le besoin pour le produit, fabriquant des considrations, et les problmes de dveloppement futurs. La premire section du rapport traite le besoin pour le systme de ECAP et les conditions qui doit tre rencontr comme a fait la mise en page de par le client. Le but principal du systme sera oblig protger des troupes militaires amricaines des assauts de projectile reus, en dtruisant la menace avant qu'il peut ait caus des dommages. Les aspects techniques de ce systme sont faits la mise en page de dans la deuxime partie du rapport. Cette section inclut l'information sur la direction, le contrle, les dtecteurs, le pouvoir, l'analyse structurale et lance des plate-formes. Le systme de direction emploie un algorithme de contrle dynamique pour fournir la production au systme de contrle. Le systme de contrle consiste en une srie de thrusters a aliment par le propulseur de fuse solide, qui applique jusqu' 38 N de force. Une CASQUETTE-12087 pouvoirs de pile thermiques la balle et le lance la plate-forme est le MK3. Cette section inclut aussi l'analyse excute utilisant simulations dans les deux six et trois degrs de libert. Les points principaux de chacun de ces systmes et comment ils ragissent rciproquement sont donns, mais l'information plus spcifique peut tre trouve dans les annexes du rapport. La section finale des adresses de rapport fabriquant des procds, le rsum de l'information technique, et fait la mise en page d'aussi des Munitions Progressivesles recommandations de s et les projets pour le dveloppement futur du systme de ECAP de Papillon Super.

ECAP Compliance List

Specification:

CDD location: Report location:

Maximum range of 4 km

2.1.4

1.2.2

Mimim Range of .5 km

2.1.4

1.2.2

System must hit 12 Targets @ 4

2.1.4

1.3.3

Second intervals

Accuracy

2.3.1.2

1.2.2

Maximum burst of 15 shells per target

2.3.1.2

1.2.3

Maximum crosswind of 65 kph sustained and

2.3.1.3

1.2.4

85 kph gusts.

Weather conditions

2.3.1.3

1.2.3

Maximum Outer Diameter of 40 mm

2.4.2

1.2.2

Maintenance

2.4.4.1

1.2.4

Compatible with current 40mm gun systems

2.4.4.1

1.2.4

Reliability

2.4.5.1

1.4

20 year minimum shelf life

2.4.5.2

1.2.4

System safety

2.4.7

1.2.4

Launch platform: MK44 or better

3.1.4

2.8

Kill mechanism: Hit-to-kill

3.1.5

2.2

Table of Contents

viiiList of Figures

List of Tablesix

IPT 3: Feasibility of Enhanced Counter Air Projectile (ECAP)1

3.01.0 ECAP-Enhanced Counter Air Projectile1

1.1 The Need [W. Gladden]1

1.2 The Requirements [E. Chapman]1

1.2.1 Requirements List1

1.2.2 Functional Requirements2

1.2.3 Environmental Requirements2

1.2.4 Interface and Safety Requirements3

1.3The Solution [S. Johnson]3

1.3.1Concept Overview3

1.3.2Dimensional Properties4

1.3.3 Operations Scenario7

1.4 The Performance [W. Esquibel]8

1.5The Implementation [B. Phillips]9

1.5.1 Design and Research Phase9

1.5.2 Testing Phase9

1.5.3 Implementation10

4.02.0 Technical Description of Methods Used10

2.1 Project Office [W. Gladden]10

2.2 Systems Engineering [B. Phillips]11

2.3 Seekers and Guidance [M. Youngblood]14

2.3.1 Methods and Assumptions14

2.3.2 Results and Discussion16

2.3.2 Possible Drawbacks17

2.4 Control [T. Smith]17

2.4.1 Methods and Assumptions17

2.4.2 Results and Discussion19

2.4.3 Spin Considerations22

2.5 Navigation and Power [E. Chapman]23

2.5.1 Methods and Assumptions23

2.5.2 Results and Discussion23

2.6 Modeling and Simulation [A. Brewer]24

2.6.1 Methods and Assumptions24

2.6.2 Results and Discussion25

2.7 Advanced Analysis [C. Ducasse and R. Monery]27

2.7.1 Methods and Assumptions27

2.7.2 Results and Discussion28

2.7.3 User Defined28

2.8 Launch Platform/ Prototyping [R. Hall]28

2.8.1 Methods and Assumptions28

2.8.2 Results and Discussion28

2.9 Trade Studies and Interactions of Subsystems [M. Ray]29

2.9.1 Examples of Trade Study Affects on Overall System29

2.9.2 System Integration30

5.0Implementation Issues33

3.1 Production Cost [T. Lingenfelter]33

3.2 Manufacturability [C. Steely]33

3.3 Test Schedule [M. Youngblood]35

3.4 Discussion of Application and Feasibility [R. Hall]36

4.0 Company Capabilities36

4.1 Company Overview [T. Smith]36

4.2 Personnel Description [W. Gladden]38

5.0 Summary and Conclusions [M. Ray]40

5.1 Summary of Design Process40

5.2 Conclusions as to Functionality, Manufacturability, and Cost Efficiency40

5.3 Feasibility and Choice Rational40

6.0 Recommendations [T. Lingenfelter]41

6.1 Recommendations for the search of new types of technologies41

6.2 Recommendations for the launch platform41

6.3 Recommendations for the guidance systems42

6.4 Recommendations for Controls42

References [W. Gladden]43

Appendix A -Concept Description Document1

Appendix B -Electronic File Index [W. Gladden]2

Appendix C -Project Office (W. Gladden)1

Appendix D Systems Engineering (W. Esquibel, M. Ray, B. Phillips)1

Appendix E Seekers and Guidance (M. Youngblood)1

Appendix F- Control (S. Johnson, T. Smith)2

Appendix G- Navigation and Power (E. Chapman)3

Appendix H - Modeling and Simulation (A. Brewer, C. Steely)4

Appendix I - Advanced Analysis (C. Ducasse, R. Monery)5

Appendix J - Launch Platform/ Prototyping (T. Lingenfelter, R. Hall)6

Appendix K PRODAS Documentation on Benchmark Trajectories (A. Brewer, C. Steely)7

Appendix L Other Ideas/Concepts (M. Ray)8

List of Figures

4Figure 1: Concept Drawing

Figure 2: Three-View Drawing5

Figure 3: Internal Geometry6

Figure 4: PRODAS Stability Model6

Figure 5: Operations Scenario7

Figure 6: Cross Sectional Drawing of the ECAP12

Figure 7: Bullet Control Features18

Figure 8: Diagram of Nozzle20

Figure 9: Fin Design22

Figure 10: Z vs Time graph26

Figure 11: Y vs Time graph27

Figure 12: CFD Model of Thrusters firing28

Figure 13: Stress model of bullet28

Figure 14: CFD model of flow with Thrusters firing28

Figure 15: Bofors MK329

Figure 16: Overall Systems Interaction flowchart30

Figure 17: Interior Bullet Systems Interaction Flowchart32

List of Tables

2Table 1: Overall Configuration of the ECAP Weapon System

Table 2: ECAP geometries (measurements in mm)5

Table 3: Values for PRODAS stability Model6

Table 4: Final Concept Evaluation9

Table 5: Summary of Technical Parameters Calculations12

Table 6: ECAP Engineering Summary13

Table 7: Propellant Evaluation Table20

Table 8: Propellant Properties21

Table 9: PRODAS Results26

Table 10: cRocket Results27

Table 11: Dimensions and performance data28

Table 12: Component Price List for the Super Moth33

Table 13: ECAP Test and Development Schedule35

Common Terms and Acronyms List

Word or symbol

Comments

AMRDEC

Army Aviation and Missile Research, Development, and Engineering Center

MAP

Mortar or Artillery Projectile

ECAP

Enhanced Counter Air Projectile

CDD

Concept Description Document

MMW

Millimeter Wave

Ogive

The nose of the bullet

CP

Center of Pressure (Aerodynamic Center)

CG

Center of Gravity

Cd

Coefficient of Drag

ASL

Above Sea Level

MEMS

Micro-Electro-Mechanical Systems

CL

Center Line

IR

Infared

Section 2.3 Variables, ordered by occurance

S

Target Signal Power

P

Transmitted Pulse Power

AD

Aperture Area of Designating Laser

Adel

Aperture Area of Laser Seeker Onboard Missile

Target Cross-section Area

Target Back Scattering Coefficient

Laser Wavelength

RD

Range from Designator to Target

Rdel

Range from Target to missile

Xi

x-coordinate of the center of one element

Xbar

x-coordinate of the centroid

Ai

Surface area of one element

Yi

y-coordinate of the center of one element

Ybar

y-coordinate of the centroid

ft

Focal Length

x1

Distance from Lens to the Array

x2

Distance from Lens to the Target

n

Index of Refraction for Lens

FOV

Field of View

S

Linear Dimension of Array

R

Range to Target

J

Target Radiant Intensity

A

Atmospheric Transmittance

Do

Entrance Diameter of Optics

NA

Numerical Aperture

D*

Detector Sensitivity

o

Optics Transmittance

W

Instantaneous FOV of the Seeker

F

Noise Bandwidth

S/N

Minimum Signal to Noise Ratio for Target Detection

n1

Index of Refraction of Air

n2

Index of Refraction of the Nose material

(1

Angle of Incidence

(2

Angle of Refraction

End Section 2.3 Variables

3-DOF

Three Degrees of Freedom

MathCAD

A Mathematical Analysis/Simulation Software Package

PRODAS

A Powerful Projectile Simulation Software Package

GAS 2.0

A Propulsion Analysis Excel Spreadsheet by Dr. Robert A. Frederick

Section 2.4 Variables

T

Thrust

CT

Thrust Coefficient

A*

Area Ratio

Po

Chamber Pressure

r

Burn Rate

a

Burn Rate Coefficient

n

Burn Rate Exponent

End Section 2.4 Variables

AMCOM

Aviation and Missile Command

DC

Direct Current

LLC

Limited Liability Corporation

cRocket

A Trajectory Analysis Program

FINNER

PRODAS Fin Analysis Module

CONTRAJ

PRODAS Thruster Analysis Module

Cma

Pitching Moment

Z

Vertical Displacement

Y

Horizontal Displacement

CFD

Computational Fluid Dynamics

CMOS

Complementary Metal Oxide Semiconductor

CAD

Computer Aided Design

ESTACA

cole d'Ingnieur du Transport

BOOST

Barbie Outfit Organizer Slider Thing

AIAA

American Institute of Astronautics and Aeronautics

PSC

Project Standard Conditions

UAH

University of Alabama in Huntsville

IPT 3: Feasibility of Enhanced Counter Air Projectile (ECAP)

3.0 1.0 ECAP-Enhanced Counter Air Projectile

1.1 The Need [W. Gladden]

In the age of smart bombs that can destroy a building with heretofore-unknown accuracy and safety for the bomber, it is one of the great ironies that the single greatest killer of American soldiers is the simple mortar. In face-to-face fighting, the soldier on the battlefield is totally unprotected from this sort of relatively unsophisticated threat. To date, there is no system capable of protecting a squad-sized and up unit from this form of attack.

New reports from Iraq and Afghanistan give witness to the toll that this lack of protection takes on Americas fighting men. Therefore, Progressive Ammunition is developing a solution to this problem for the US Army Aviation and Missile Research, Development and Engineering Center (AMRDEC). AMRDEC has identified the need for an anti-MAP (Mortar or Artillery Projectile) system, and has been determined to be the best possible organization to further develop and test such a system, due to their present assignment as a US Army missile development center.

As was stated before, an America soldier, under mortar or artillery attack, is basically helpless. He or she can only hunker down and wait with the rest of the unit and hope the incoming shell does not hit their position. The Enhanced Counter Air Projectile (ECAP) can change all of that. As will be seen in this report, the ECAP system has the capacity to kill an incoming target (as defined by the CDD, see Appendix A) at distances ranging from 500 meters to four kilometers distant from the gun position. In other words, this system has the capacity to eliminate the threat of a mortar/artillery/rocket attack on an American position, and to do so far enough away that the troops are not exposed to threats of shrapnel.

America, in the current environment of the War on Terror and in the possible realities of other, future conflicts heretofore unimagined, will require a reliable anti-MAP system. Our men will continue to fall under attack from mortar shells, and larger, in the two current theatres of operation (Iraq and Afghanistan). We owe it to them, our soldiers who are placed in harms way for our sake and the sake of the country as a whole, to do whatever is humanly possible to preserve their lives in the face of the enemy. Our current enemy is ruthless, determined, and dependent on attacks and technologies that smart bombs are simply unable to counter. The ECAP can counter and remove at least one of those attacks, the mortar round, from the enemys options. It will protect our troops; that alone is worth development.

1.2 The Requirements [E. Chapman]

1.2.1 Requirements List

AMRDEC, our customer, has presented UAH with requirements that would meet the need described above and ultimately provide a solution to the problem. Table 1 lists the CDD system configuration, with some company-defined specifications.

DESIGN ELEMENT

Concept Name

Gun Platform

NA

Acquisition Sensor

IR

Projectile

40mm

Shell

NA

Projectile Rotational Velocity

40 Hz

Guidance Concepts

Homing Configurations

Semi-Active

Homing Sensors

Radar

Actuators & Controls

Bent Nose

Computer & Electronics

Both

Power

Thermal Batteries

Structures & Packaging

NA

Warhead

Fragment

Table 1: Overall Configuration of the ECAP Weapon System

1.2.2 Functional Requirements

The ECAP projectile must be 40mm in diameter, with a length that is compatible with the gun system that is chosen. The ECAP projectile must guide to intercept the primary threat and destroy it by a method of hit to kill. The primary threat includes rockets, artillery, and mortars, which can range in sizes from 80mm to 300mm. The ECAP projectile must meet have and effective range of 500 meters to a maximum threshold range of 2000 meters and maximum objective range of 4000 meters in all weather conditions. The ECAP must achieve a greater than 90 % probability of hit against a moving threat target. The ECAP must be able to handle a threat target moving at a velocity of up to 1800 kilometer/hour. The ECAP system must maintain a maximum threshold burst of fifteen rounds and maximum objective burst of ten rounds of ECAP projectiles.

1.2.3 Environmental Requirements

The ECAP must be capable of performance in the same environment as the host platform and accuracy requirements must be over the effective range during daylight as well as darkness. The ECAP must withstand temperatures from +71o C to -45 o C at altitudes from 0 to 12, 190 meters above sea level. ECAP must operate before and after exposure to temperature from +63o C to -43 o C at altitudes from 0 to 4570 meters above sea level. The ECAP must be able to operate in wind conditions up to 65 kilometer/hour sustained wind speed with gusts of up to 83 kilometers/hour.

1.2.4 Interface and Safety Requirements

The ECAP must provide operational interface and integration with other elements comprising the ECAP weapon system and with the acquisition sensor chosen. The ECAP system must be safely transportable and must not develop new or unique packaging, handling or transportation requirements. The ECAP projectile must be designed such that an onboard guidance failure must not affect the ability of the ECAP projectile to launch, fly, and detonate as an unguided 40 mm projectile. The ECAP must require no maintenance and must produce no harmful or unusual chemicals, gasses or vapors and must have a shelf life of 20 years. The materials chosen must do so on the basis of suitability and availability in this country. The ECAP must remain safe after being subjected to a 12.2meter drop onto a 76.2 mm thick steel plate, which is backed by reinforcement concrete 0.61 meters thick. Finally the ECAP must not require maintenance and operational checks of the components during their stated lives.

1.3 The Solution [S. Johnson]

1.3.1 Concept Overview

The Super Moth is a highly innovative interceptor that combines high maneuverability, superior aerodynamic attributes, and small packaging to provide a real world solution for force protection from incoming artillery/missile threats. Every component and technology that is required for the Super Moth to become an operational entity is available or achievable right now. This solution could provide the military with a force protection system in the very near future. The design of the Super Moth relies on simplicity and few moving parts to meet or exceed the operational capabilities set forth by the CDD.

The most critical features of the Super Moth are the solid fuel control system, the thermal battery, and the guidance/navigation system. The solid fuel control system incorporates a solid rocket propellant that acts as a gas generator, a complex flow control system comprised of a four valve manifold, and nozzles that accelerate the flow of exhaust gases to provide maneuverability in the form of pitch and yaw control. A thermal battery provides power for the ignition of the solid rocket motor, operation of the guidance computer/sensors, and actuation of the valves in the manifold. Guidance and navigation of the ECAP is accomplished by a system that incorporates a clear lens placed on the nose of the ECAP for focusing laser energy, a photo sensor array for sensing the laser as focused by the lens, and a guidance/navigation computer that processes the information relayed by the photo array to generate commands for controlling valves in the manifold for aerodynamic control. Ground based systems that are critical to the operation of include a laser emitter and MMW radar, which provide painting of the target and target acquisition, respectively.

The Phase II concept that was selected by the team to pursue in Phase III was thrown out. After more careful inspection, the vectored thrust concept proved to be a serious packaging problem. However, the team decided to pursue the concept of using a solid rocket motor for control. The only other way to use the solid rocket motor for control was to place a number of nozzles around the perimeter of the ECAP at some axial location and direct exhaust gas to these nozzles to provide attitude control. This did not solve all packaging issues because of the size of the projectile that the team had to begin with and the considerable amount of space required by the control system. As a result of this, the guidance/navigation system had to be a design that was simple and elegant. It does not require any space outside of the nose of the projectile, which leaves the rest of the internal volume for the battery and control system. An additional factor that allowed more room for the control system was the decision to use of thermal battery to meet power requirements. The thermal battery has a high energy density, which provides for excellent packaging characteristics.

Figure 1: Concept Drawing

1.3.2 Dimensional Properties

Figure 2 shows a three-view drawing of the ECAP. It contains a side view, front view, and isometric view. Geometries for the ECAP are listed in Table 2. Figure 3 shows the internal geometry values for each of the ECAP systems. The system locations are defined by overall space allocation; exact measurements can be found in section 2.

Figure 2: Three-View Drawing

Total Length

220

Band Width

10

Outer Diameter

40

Band Thickness

2

Inner Diameter

30

Thrust System Length

60

Ogive Length

75

Thermal Battery Length

40

Ogive Radius

250

Seekers & Guidance Length

60

Boattail Length

40

Bulkhead Widths

2.5

Boattail Radius

260

Manifold Length

35

Boattail Left Diameter

32

Manifold Left Diameter

22

Fin Length

40

Manifold Right Diameter

30

Outer Fin Diameter

90

Manifold Reference Position

5

Cylindrical Body Length

105

Thruster Array Reference Position

210

Table 2: ECAP geometries (measurements in mm)

Figure 3: Internal Geometry

Figure 4: PRODAS Stability Model

Figure 4 shows the relative locations of the CP and CG. Table 3 gives the dimensional values used by the model. Measurements of the CG and CP are taken from the tip of the nose.

Muzzle Velocity

1100.0 m/s

Aircraft Velocity

0.0 m/s

Air Density

1.22500 kg/m^3

Air Temperature

15.0C

Muzzle Spin Rate

0 deg/min

Gun Muzzle Twist

-

CP from Nose

13.56 cm

CP from Nose

3.39 Calibers

CG from Nose

12.39 cm

CG from Nose

3.10 Calibers

Mach Number

3.23

Gyro Stab Factor

0.000

Static Margin

.29 Calibers

Cd at Muzzle

0.353

Deceleration

277.36 m/s/1000 m

Muzzle Jump Factor

0.206 mils/rad/sec

Table 3: Values for PRODAS stability Model

1.3.3 Operations Scenario

The mission profile that is required for evaluation is to intercept 12 incoming targets traveling at 300 meters per second that are spaced apart by 4 second intervals along the same trajectory. Standard temperature and pressure conditions apply to operations scenario. There is assumed to be electronic or environmental interference with the systems on board the ECAP or the ground-base systems. Target acquisition is achieved at 8000 meters and the attempt to intercept the targets is occurring at an altitude of 500 meters and a downrange distance of 2000 meters. The results of the ECAPs trajectory and a target trajectory spreadsheet are compared to see if both projectiles arrive at the same point in space at the exact same time.

The incoming target is acquired by the MMW radar on the ground and directs the laser designator to paint the target with two individual lasers. Laser designators must paint each individual target for the entire time until the target is intercepted. The two MK3 cannons will launch a salvo of 12 shells in 1 second and then the ECAP will begin the target acquisition process. Power comes on line at this point as the thermal battery becomes active at launch. A lens on the front of the ECAP focuses the laser energy that is reflected from the target on the photo sensor array located inside the nose of the bullet. This information is passed to the navigation computer, which conditions the data for use by the guidance computer. A control model contained in the guidance computer will analyze incoming data and provide output in the form of commands for the valve manifold. These commands are processed through an array of relays that convert the commands from the guidance computer into power that energizes individual valves. At some point during this process, the solid rocket motor is ignited to start the generation of exhaust gases. The necessary valve is actuated and exhaust gases are directed through the corresponding nozzle to produce thrust in the direction it is needed. When a target is destroyed, the ECAP will begin searching for a new target to try to intercept.

500m 2km 4km

Variety of Sensors

Launch Platform/

Gun System

UAV

RW

Guided

Projectile

Artillery/Mortars

Rockets

Fire Control Radar

ECAP Concept of Operation

ECAP Concept of Operation

Figure 5: Operations Scenario

1.4 The Performance [W. Esquibel]

The ECAP (Super Moth variant) intercepts and destroys the primary threat, which includes rockets, artillery and mortars (80mm to 300mm in diameter). It has an effective range from 500 meters to a maximum threshold of 2000 meters and maximum objective of 4000 meters. The Super Moth has exceeded several of the CDD requirement with an accuracy of 95% probability of hit against a threat moving up to 1800 km/hr in wind conditions of 65+ km/hr (evaluated at 85 km/hr) with gusts up to 85 km/hr, utilizing a maximum threshold burst of 12 rounds and maximum objective burst of 10 rounds of ECAP projectiles. It will perform in the same environment as the launch platform, day or night. Further testing will be required to verify the ECAP operates after exposure of 71 C to 45 C and altitude from 0 to 12,190 m ASL, and operates during and after exposure of 63 C to 43 C and altitude from 0 to 4,570 m ASL.

The Super Moth has a 40 mm diameter and a length of 220 mm. It does not exceed the maximum transportable weight of wheeled or common carrier, rail, ship or fixed or rotary wing aircraft and it does not require a unique or newly developed transport/carrier system.

It does not require any additional tooling during installation and removal. It does not emit anything toxic during storage and it has a shelf life of 20 years. Further testing will be required to verify its weapon system has a .97 reliability during tactical missions and it does not require maintenance or checks. Field-testing must be performed to insure the safety of the ECAP after being dropped 12.2 m onto a 76.2 mm thick steel plate, which is backed by reinforced concrete 0.61 m thick and if it complies with all safety requirements.

The table below shows how the performance of the ECAP matches with the requirements of the CDD. The performance evaluation was based on the assumptions and procedures detailed in Section 2.

CDD Attribute

Concept Name

Evaluation

CDD Requirement

Maximum Range of Threat

4 km

Meets

2 km Threshold;

4 km Objective;

Minimum Range of Threat

0.5 km

Meets

0.5 km

Altitude of Threat

500m

Meets

100 m to 1000 m

Projectile Dia.

40 mm

Meets

40 mm

90 % Probability of kill Accuracy

12 Shots Threshold;

10 Shots Objective;

95% Probability

Exceeds

15 Shots Threshold;

10 Shots Objective

Total Targets

112 Targets;

4 s. Intervals

Meets

12 Targets;

4 s. Intervals

Closest approach

0 mm

Exceeds

Hit-to-Kill (140 mm)

Crosswind

85 km/hr sustained

Exceeds

65 km/hr sustained;

83 km/hr gust

Gun System

MK 3

Does not Meet

MK 44 or Alt

Environmental

Standard Environments

Partially Meets

Military Environments

Storage/ Trans.

Military Environments

Meets

Military Environments

Reliability/ Safety

Military Environments

Meets

Military Environments

Table 4: Final Concept Evaluation

1.5 The Implementation [B. Phillips]

The ECAP will be easy implemented into current arsenals. The basis for the system is the MK-3, which the Army is already familiar with. The gun itself should need little to no modification. Also the Super Moth round will be capable of being fired in sequence with any current conventional round that the MK-3 is able to fire. The system will be very user friendly, only requiring a soldier to arm the gun and turn on the radar acquisition and laser tracking systems. Computers and the bullet will do the rest of the job and take down a 240mm rocket using only 12 ECAP rounds. All of this capability without user intervention or even pushing a firing button if desired.

Although the team has designed a bullet that is believed to be producible and have researched as in-depth as possible on the aspects of making the system a reality there are some areas that will need further research. The ECAP should be implemented to a 12-year deployment schedule. This period will be divided into three sections, the design and research phase, the testing phase, and field-testing phase. The design and research phase will require 7 years and the testing phase will require 3 years, thus allowing 2 years for field testing.

1.5.1 Design and Research Phase

Initially we expect the biggest obstacle of the development period will be designing the control system for the thrusters, the thrusters themselves, and the solid propellant. This should be the first area to be looked into and will be allotted 4 years of development time. Next, the seekers and guidance sections need to be perfected requiring another 2 years. Some improvement will also be required on the electrical power supply. Although we believe the thermal battery to be a very good fit here, there should be a specific battery designed to fit the particularly demanding needs of this project. Set aside 1 year for investigation in this area after the other systems have been designated and requirements are known. Finally, the MK3 platform base and vehicle enhancements to carry the system should be made. This can be accomplished congruently with the previous development.

1.5.2 Testing Phase

The testing phase will consist of static and dynamic test to verify the operation of the Super Moth. The first testing will be to test the structure, fins, and electronics under the firing and flight loads. Second, wind tunnel testing to verify the aerodynamic properties of the ECAP with both the fins tucked and deployed. Also multiple firings of the bullet structure will be done without arming the guidance and control systems to achieve a baseline for future tests. Next firing the round with all electronics operating but without the thrusters operating to verify the control algorithms of the guidance system and proper operation of the sensors. This will also be the initial set of tests for the radar acquisition and laser tracking systems. Finally, a set of full systems tests will be done to verify complete operability of the Super Moth.

After the testing phase is complete the system will be field tested by soldiers to verify firing parameters and safety procedures. After this two-year phase the unit will be ready for deployment into the general infantry and armored divisions of the Army.

1.5.3 Implementation

The number of lives that will be saved by developing this system easily offsets the cost and time required for implementing the Super Moth. After the initial expense of design and testing the bullet will be cheaply built for its capability allowing for multiple systems to be deployed to cover larger areas of engagement. The ECAP will be easily integrated into existing tactical schemes of the military so that it can be immediately deployed to any theater of hostility. With the capability of utilizing both conventional rounds and the ECAP round, the Super Moth will also be capable of engaging multiple targets types by soldier selection of manual or automatic operation, thus changing roles as the battlefield changes.

4.0 2.0 Technical Description of Methods Used

2.1 Project Office [W. Gladden]

This is the second section of the report, wherein we will present details of the technical capacity of the ECAP round. It is arranged in nine sections: Project Office, Systems Engineering, Seekers and Guidance, Control, Navigation and Power, Modeling and Simulation, Advanced Analysis, Launch Platform and Prototyping, finalized by Trade Studies and Interaction of Subsystems. Each of these sections details the methodologies and assumptions employed by each sector of the company, as well as the conclusions and design implementations reached and utilized by the company sections. Combined, this section provides a detailed overview of the Super Moth ECAP variant, and the steps taken to reach this final design.

The purpose of the Project Office was to coordinate the activities of the various disciplines (beyond that coordination tasked to the System Engineers) and to coordinate with AMRDEC to ensure that the final design met the requirements of the CDD. The Project Office was also responsible for implementing and enforcing the overall team strategy. This strategy was more of a code of interpersonal conduct than of a directed research and development plan, but it did delve into that area as well. The primary focus of the strategy, that being the code of conduct, simply stated that the members of the team would respect each other and would not digress into personal attacks in the course of discussion. Development coordination evolved throughout the course of the design process, generally consisting of the various design disciplines concentrating on their tasks and parts, but kept mindful of the over-all requirements of power and packaging with the aid of the systems engineers.

Several critical issues were encountered over the course of the design phase. The first and almost disastrous issue was that it was discovered, mid-development, that the initial control concept, that of a rocket engine within the bullet with a controllable thrust vector, would require more propellant than there was bullet and shell space to work with. Consequentially, the design was changed mid-stream from the rocket concept to a thruster concept. This raised its own set of issues, as further analysis of the MEMS-type thrusters used in the initial thruster concept revealed that they would neither burn long enough nor with enough force to give the control authority required.

Aside from the control problem, there was one other issue that held sway as a proverbial thorn throughout most of the development: power. It was noted as an issue from the start when the initial baseline design team reported that their concept drained the power system dry in less than a second. This issue was finally overcome, but it was one that affected the entirety of the design process. The issue of a power budget was on the back of everyones minds in the course of choosing systems, and it had a great effect on what could and could not be done.

2.2 Systems Engineering [B. Phillips]

The design process for Team 3 final concept centered on modifying design selections to meet unforeseen limitations and making the final concept as feasible and cost effective as possible. The originally selected concept was based on a vectored thrust idea for maneuvering and controlling the bullet. Shortly after the Phase 2 review further analysis of this idea revealed that the amount of propellant required to achieve the set goals greatly exceeded the volume bounded by the bullets geometry. The following brainstorming sessions resulted in selection of a system utilizing the solid propellant, but only for guidance thrusters. The idea of using a small end game thrust burst to increase the final kinetic energy was considered but dropped due to the increased complexity of adding range finding capability to the sensors and guidance electronics. The team also contemplated inserting a turbine based electrical power system, but because of cost, complexity, and power consumed for the thruster system this idea was declined in favor of a traditional thermal battery. Therefore, the final design is a bullet without a vectored thrust propulsion system, but using solid propellant for guidance thrusters, a thermal battery, with a laser based guidance and sensing system.

In order to achieve the most creative ideas and foster a freethinking environment the design process was very loosely controlled. By allowing the team members to voice opinions and ideas to the group as a whole many ideas were found that might have otherwise not come to the table if the team was constricted to single-minded ideas. This method worked very well for the team because of the respect it created for others ideas. By putting to vote any controversial topics a design was achieved that brings out the best of every aspect of the team. By the mid part of Phase 3 the far reaching minds of the team did have to be reined in to focus on one single design and produce quantifiable results for the competition.

Figure 6: Cross Sectional Drawing of the ECAP

Guidelines

Reason

240 mm Threat Diameter

Baseline Threat Specification

500 m/s Threat Horizontal Velocity

Baseline Threat Specification

Head-on Engagement

Baseline Threat Specification

2 km Range; 500 m Altitude

Threshold Maximum Range Requirement;

Intermediate Altitude Requirement

(-) 1 deg. Launcher Elevation Error

Evaluate Guidance, Low angle error most difficult

0 m/s Crosswinds, Standard Day Air

Simplification and Consistency

Assumptions

Hit-to-Kill is Volumetric Intersection of

Threat and Projectile

Evaluate Guidance

Volumetric Intersection is a closest approach

distance of no more that 140 mm

The distance between the centerline of a 240 mm rocket and a 40 mm round.

Table 5: Summary of Technical Parameters Calculations

Parameter

Units

Team 3 Concept

1. Gun Data

a) Gun Barrel Twist

cal/revRev/cal

15

b) Gun Barrel Length

m

3

c) Average Axial Acceleration in Barrel

gs

13,700

d) Maximum Firing Rate

Hz

11

2. Projectile Data

a) Diameter

mm

40

b) Length

mm

220

c) Mass

kg

1.077

d) Axial Distance to CG

mm

123.9

e) Average Density

kg/m3

4059.7

f) Spin Moment of Inertia

kg m2

0.003

3. Cartridge Data

a) Length

mm

534.4

b) Diameter

mm

60

c) Mass of Powder

kg

0.12

d) Total Mass

kg

0.975

4. Flight Data (Launch)

a) Distance to Center of Pressure

mm

135.6

b) Spin Rate

Hz

0

c) Velocity

m/s

1100

d) Mach Number

-

3.23

5. Flight Data for 2km Intercept

(PSC)

a) Launch Elevation Angle

deg

10.3

b) Maximum Lateral Acceleration

m/s2

225.6

c) Maximum Drag Coefficient

-

15.72

d) Maximum Axial Acceleration

m/s2

294.3

e) Mach Number at Impact

-

1.816

f) Impact Velocity Relative to Target

m/s

1115

g) Kinetic Energy at Impact

kJ

203.3

h) Spin Rate at Impact

Hz

0

i) Time of Impact

s

2.52

j) Closest Approach (CL to CL)

mm

0

6. Projectile Electronics Data

a) Sensor Wavelength

Hz

IR

b) Sensor Field of View

deg

20

c) Supply Voltage

V

5

d) Peak Power Required

W

0.01

Table 6: ECAP Engineering Summary

2.3 Seekers and Guidance [M. Youngblood]

2.3.1 Methods and Assumptions

The guidance system used for the Super Moth ECAP system is a semi-active homing guidance system. A ground-based IR laser illuminator is used to provide reflective energy. Two wavelengths of light will be projected via laser from the ground system to the target. The light is then reflected off the target and sensed by the onboard ECAP sensor. Two lasers provide the guidance system with a simple mechanism to determine its orientation with respect to the ground. As the light passes through the lens, the two beams are inverted. The position of the beams provides ample data to determine the bullets orientation and even roll rate. MMW radar is used in conjunction with the IR laser for target identification.

For the guidance calculations, some assumptions are needed. First, the targets surfaces were assumed to have a target back scattering coefficient of 0.7 and be diffuse. This allows for the calculation of the power needed for the ground-based lasers. Second, the target was assumed to be at a maximum distance of 4000m for the area calculations, which are also needed for power calculations. The calculations for the power are dependent on the magnitude of the energy placed on the target, the area of the lens, and the area of the reflected energy (Equation 1). The light intensity required by the sensor is calculated by Equation 2.

M

D

A

A

S

P

/

*

@

(1)

2

2

2

3

8

M

D

O

M

D

R

R

A

PA

S

l

p

srt

=

(2)

where:

S = Target signal power

P = transmitted pulsed power

AD = aperture area of designating laser

AM = aperture area of laser seeker onboard missile

= target cross-section area

= target back scattering coefficient

= laser wavelength

RD = range from designator to target

RM = range from target to missile

The laser projections are assumed to be 1 in. in diameter. Also, the recoil of the launch system was assumed to cause little interference with the ground-based system.

The IR sensor located in the nose of the Super Moth (see Figure 6) is a CMOS integrated IR sensor. The CMOS transfers the data to a microprocessor that then uses proportional navigation to calculate needed maneuvering for interception of the target through the controls. A CMOS IR sensor is much like the sensor used in most digital cameras. The major difference is in the filters used. Digital cameras use filters to reduce the amount of IR photons that pass onto the array. For the ECAP, just the opposite is done. Two filters are used to detect the specific wavelengths provided by the ground-based system. A CMOS sensor arrays columns are alternated between the two filters: one for the higher frequency and the other for the lower frequency. This allows the guidance system to detect both frequencies without the need for two separate arrays. A new silicon-compatible, sol-gel lead calcium titanate material can be used to attached the array to the microprocessor. The targeting calculations performed by the microprocessor are simple centroid calculations. The processor determines the distance of the two light beams with respect to the center of the array. Then, the controls are maneuvered so that the beams are as close to the centroid as possible. The formulas for calculating a centroid are provided below (Equations 2 & 3).

total

i

i

bar

A

A

x

X

=

*

(3)

total

i

i

bar

A

A

y

Y

=

*

(4)

The sensor was assumed to have an operating voltage of 5V at 2mA current. The sensor array was assumed to have an area of 450mm2 and the lens was assumed to have a diameter of 28.53 mm. The intensity of the light needed by the array was assumed to 1.2V/lux-sec. Finally, the focal length of the lens is dependent on the distance from the lens to the target (otherwise known as working distance), the size of the image sensor, and the size of the laser reflected off the target (Equation 5). The FOV of the lense is dependent upon the focal length, and the image size (Equation 6). The detection range can be calculated by Equation 7 below.

))

1

1

(

*

)

1

((

1

2

1

x

x

n

f

l

-

-

=

(5)

where:

fl = focal length

x1=distance from lens to the array

x2=distance from lens to the target

n=index of refraction for lens

l

f

x

S

FOV

2

*

=

(6)

where:

S = linear dimension of array

fl = focal length

[

]

[

]

[

]

2

/

1

2

/

1

2

/

1

2

/

1

2

2

/

1

)

/

(

)

(

1

)

(

D

=

*

N

S

F

W

D

NA

D

J

R

O

O

A

t

t

p

(7)

where:

R = range to target

J = target radiant intensity

A = atmospheric transmittance

DO = entrance diameter of optics

NA = numerical aperture (focal length/diameter)

D* = detector sensitivity

O = optics transmittance

W = instantaneous FoV of the seeker

F = noise bandwidth

S/N = minimum signal to noise ratio for target detection

In order to keep the shape of the nose aerodynamically efficient and satisfy the optical requirements, the end of the nose in front of the lens would need to be made from some transparent engineering material. This material would cause some refraction of the light. The amount of refraction can be calculated using Equation 8.

1

2

1

2

sin

*

sin

Q

=

Q

n

n

(8)

where:

n1=index of refraction of air (approx. 1)

n2=index of refraction of the nose material

(1=angle of incidence

(2=angle of refraction

With this angle calculated, it can be easily integrated into the control algorithms so that a kill might still be accomplished.

2.3.2 Results and Discussion

Most of the calculations were simplified and some values were taken from research of CMOS sensors and various lenses. With a focal length of 5 mm (this is a constraint due to the dimensions of the Super Moth), the equivalent FOV is approximately 63. The power needed for the laser ground based system was not calculated but assumed to be large. The centroid and orientation algorithms provided above will work well for small roll rates, but the rate of recording and processing might be too slow for large roll rates. The power usage, size, and low cost of CMOS sensors makes them the optimal choice for the ECAP system. A CMOS sensor was chosen as apposed to a CCD sensor due to the significant savings in power uses. The resolution lost in the trade-off is acceptable in this situation because the sensor is not producing an image. The main objective of the system is to detect the two frequencies in the IR range and determine their centroid and its location in relation to the sensors centroid. A pinhole could have been used rather than the lens, but the power and resolution of the sensor would have been worse. The pinhole would provide a more accurate distance calculation though. Many tables and figures are provided in the appendix to better explain the concepts taken into consideration for the seeker and guidance system.

2.3.2 Possible Drawbacks

As with any system, there are some misgivings, the use of IR in some weather conditions is almost impossible. To deal with this problem, a MMW sensor or GPS system would need to be coupled with the IR sensor. This would provide visibility in almost all weather conditions, but the size constraints may not permit it. Another potential drawback is the incident noise provided by the sun and other light sources. The filtering system mentioned above may not be sensitive enough to filter this noise out. Finally, this system would call for the use of more than one ground-based system to detect and destroy multiple targets due to the fact that the laser must be trained on the target until the target is destroyed. Cost and logistics may be a limiting factor in this area.

2.4 Control [T. Smith]

2.4.1 Methods and Assumptions

The proposed control system for the ECAP consists of a gas generator fueled by solid rocket propellant. An electric squib ignites the propellant, and a valve system directs the exhaust to four nozzles that are arranged around the circumference of the bullet. Thrust can be directed to one nozzle to provide maneuverability while the other three nozzles are not operating, or thrust can be directed out of all four nozzles at the same time to allow the ECAP to hold its course. The ECAP also has a set of four fins for stability and the shape of the exterior was modeled after a 50-caliber bullet. The shape consisted of three basic parts: an ogive nose cone for streamlining the front of the ECAP and reducing the incidence of shockwaves, a straight body cylinder for maximizing the volume of the bullet for the internal components, and a boattail end to reduce the base drag. The boattail also provides a hub for the fins and thrusters. Wrap-around fins were added for stability, as the bullet will be de-spun in its final configuration. These fins also provide advantages in the way of packaging.

Figure 7: Bullet Control Features

The approach used to design the control system for the ECAP involved a four-step process. The first step was to choose an initial design idea for the ECAP. The second step was a feasibility study using a 3-DOF MathCAD control algorithm (see Appendix F), which implemented the general equations of motion and a filter to provide stability augmentation. This showed the team whether the proposed design would be possible. The third step was to simulate the proposed system in PRODAS in order to get an idea of the thrust and size of the components that would be needed to meet the requirements set forth in the CDD. The final step was to design the control system components to be within the parameters determined by the analysis.

The assumptions made for the feasibility study, using the MathCAD control algorithm, were that the bullet is not spinning, that only maneuverability in the vertical direction will be evaluated, all of the aerodynamic coefficients used in the feasibility study were rough estimates based on interviews with an experienced professional, and finally if the required maneuverability could be achieved in the vertical plane then the same result would apply to the horizontal plane. For the PRODAS simulation the primary assumption was that the bullet was not spinning, and to this affect the controls team modeled the ECAP without wrap-around fins, as they would induce spinning. To compensate for the spinning, a complex control model would have to have been implemented in PRODAS and sufficient time did not exist to be instructed in this matter. Provisions for stopping the spinning of the projectile are discussed in Section 2.4.3. The primary objective for using PRODAS was to evaluate the overall maneuverability afforded by the thrusters and to show that incoming targets could be intercepted. Also it is important to note that the results reported are assuming that the temperature is at 60(F.

Once the analysis was complete propellant properties n, a, and p where determined from a plot of the burning rate versus chamber pressure. The propellant properties were input into an excel program GAS 2.0 (see Appendix F), which was provided by Dr. Robert Frederick, an Associate Professor at UAH. The program is specifically designed for evaluating a solid fuel, end burning gas generators. Propellant properties, interior ballistics of the thrust chamber, throat diameter, and area ratio are input into the GAS 2.0 program. It provides outputs of how chamber pressure, thrust and mass flow rate. The thrust was determined from the equation:

o

T

P

A

C

T

*

=

(9)

In this equation T is the thrust, CT is the dimensionless thrust coefficient, A* is the area ratio between the throat area and the exit area, and Po is the thrust chamber pressure.

The burn rate was determined by the equation:

n

o

aP

r

=

(10)

The burn rate, r, is defined by the chamber pressure Po, the burn rate coefficient, a, and the burn rate exponent, n. Both a and n are defined by the propellant chosen. The burn rate equation was used to determine the amount of time that the thrusters would be able to provide control during both non-maneuvering mode and maneuvering mode. The thrust equation would indicate how much thrust could be used in the PRODAS simulation. A propellant had to be selected that burned at a high enough chamber pressure to produce significant thrust and possessed an optimum burn rate exponent so that the chamber pressure would not be reduced so greatly in the non-maneuvering mode of the ECAP that the solid motor would extinguish itself. Chamber pressure is reduced significantly in the non-maneuvering mode of the ECAP due to the exhaust gases being directed out of four nozzles, which increases the effective throat area of the nozzle by a factor of four. This in turn causes a significant reduction in the burn rate of the propellant, which has advantages that are discussed in Section 2.4.2.

2.4.2 Results and Discussion

It is important to note that the results reported are assuming that the external temperature is 60(F. The amount of maneuverability changes with ambient temperature. A table of the results at the maximum and minimum temperatures in the range can be found in Appendix F.

The nozzles are arranged at 90 intervals around the circumference of the bullet and their axial location is 210mm from the nose of the ECAP. Placing the thrusters at this location maximizes the pitch and yaw control afforded to the ECAP. This will also lessen the effects of the thrusters firing on key aerodynamic properties such as lift and drag. The nozzles themselves are made out of aluminum, which prevents the center of gravity from moving farther back and decreasing the maneuverability. The amount of space allotted for the propellant itself is 60 mm long and 30 mm in diameter. A squib will be placed at the open end of the propellant to initiate ignition of the solid rocket motor. Specific information about the squib can be found in Appendix F. The thrust required to meet the maneuverability requirements for the ECAP was found to be 38.3 N. This thrust will provide enough control to hit the closest incoming target. This target requires the most thrust therefore, the control system was designed to meet this maximum requirement. The thrust acquisition in PRODAS accounted for the mass of the bullet, aerodynamics of the bullet, rotational inertia, and dynamic characteristics of the flight in a 6 DOF simulation.

A parametric analysis was performed with GAS 2.0 to acquire the exit to throat area ratio for the nozzle and the diameter of the nozzles throat. A nozzle throat diameter of 1.524 mm, an area ratio of 6, and an exit diameter of 3.7338 mm was selected to achieve the thrust shown to be required from simulation for adequate control authority.

Figure 8: Diagram of Nozzle

Three propellants were evaluated and the results of these evaluations are listed in Table 6

Propellant

--

1

2

3

Type

--

JPN

AP

Double Base

[1/K]

255.3736

255.3732

255.3730

n

--

0.7417

0.1787

0.3744

a

[in psi-n/s]

0.00355

0.0889

0.0344

[kg/m3]

1,660.8

1,660.8

1,660.8

max

m

[kg/s]

0.0807

0.0090

0.0162

burn time

[s]

0.8

7.5

4.12

max thrust

[N]

190.38

19.572

38.34

max Po

[MPa]

53.303

5.861

13.114

Table 7: Propellant Evaluation Table

* Highlighted area denotes selected propellant.

**Propellant and thrust chamber performance evaluated at 60F.

***Propellant burn time accounts for operational time of gas generator at full capacity.

Propellant Type 3 was chosen for the gas generator solid fuel. It provided the right balance between chamber pressure, maximum thrust, and burn time. This propellants exact composition is unknown as it is classified material. Chemists from AMCOM were consulted on the required characteristics for the propellant and they indicated these parameters were obtainable and fit into the typical value range for a double-base propellant. Propellant Type 3 provides approximately 4.12 seconds of maximum maneuver time for the ECAP based on the size of the propellant grain. It takes approximately 8 seconds for the ECAP to reach the farthest intercept point. Obviously, the gas generator cannot operate for this length of time. However, when the ECAP is in a non-maneuvering mode the propellant burns 2.3 times slower at a burn rate of 6.324 mm/s. For instance, if the ECAP needed to use 3.75 seconds of maneuvering time then only 0.9 seconds of non-maneuvering time would be available. Since the total flight time is greater than 4 seconds for the 4 km intercept point the propellant can not be ignited at launch, but will need to be ignited at some point during the flight to ensure that maneuverability is available when it is needed. Specific propellant properties can be found in Table 7.

Propellant Properties [T = 70F unless otherwise noted]

Symbol

Parameter

Value

Isp(ideal)

Specific Impulse

229.15 s

It

Total Impulse

159 N-s

a

Burning Rate Coefficient

0.034428 in/s/psi-n

n

Burning Rate Exponent

0.374

Average Thrust (assuming no change in Chamber Pressure)

38.34 N

Average Chamber Pressure

13.12 Mpa

Non-maneuvering Chamber Pressure

Fmax

Max Thrust

38.34 N

Pmax

Max Pressure

13.12 Mpa

p

Density

1660.8 kg/m3

C*

Characteristic Velocity

4603.1 m/s

p

Propellant Temperature Sensitivity

255.37 /K

L

Length

60 mm

dprop

Diameter

30 mm

Specific Heat Ratio of Combustion Products

1.26

Number of Burning Ends

1

Table 8: Propellant Properties

The fins are added to the rear of the ECAP to provide stability, as the bullet cannot be controlled effectively unless the bullet is de-spun to the point where gyroscopic stability is non-existent. Wrap-around fins were fitted around the boattail section of the ECAP and they shall be deployed by a spring mechanism that locks them into place. It is important to note again that the simulation model did not have wrap-around fins in place. This is a reflection of the intended design. These fins provide for superior packaging characteristics, but have a one disadvantage. When the fins are deployed, a roll will be induced in the ECAP by the force with which the fins are deployed and by differences in pressure distributions over the surface of the fins. A mechanism will have to be introduced to counteract this roll for the control system to work efficiently. The fin design can be seen in Figure 7.

Figure 9: Fin Design

One of the final components of the control system is the valves. The space allotted for the valves is 20 mm in diameter and 30 mm in length. All four valves and any relays or piping must fit within this space. The valve requirements are that they can withstand a maximum chamber pressure of 13.79 MPa (2000 psi), a temperature of 1500(C, and an initial acceleration loading of 2600 gs at launch. The current valve diameter is 3.524 mm, which corresponds to the diameter of the nozzle before it begins to converge. More information can be found in Appendix F.

2.4.3 Spin Considerations

The spin of the bullet is one of the major problems with the control of the bullet. It is much easier to fire a thruster that is on the bottom of the bullet to make it move up when the same thruster is always on the bottom of the bullet. For this reason the team decided that it was important to have the bullet de-spun. This simplified the analysis and the simulation and allowed the team to show that the control system has the maneuverability and stability to reach the targets. Having the control authority to hit the targets was the teams first priority; therefore the assumption was made that the bullet could and would be de-spun by the combination of a slip ring, bent fins, and specialized autopilot software installed in the guidance system.

The method used to de-spin the bullet was not analyzed as thoroughly as the team had hoped and it was assumed that the method would work. A slip band was used to slow or stop the spin all together within the rifled barrel. The slip band engages the rifling of the barrel, which causes a small torque on the bullet that decreases the spin rate. The band was learned about in the PRODAS course as a possible solution to the spin problem. However, the assumption made that this would solely stop the spin is not realistic. Also it was assumed that the band did not decrease the bullet diameter, which in reality it would. Another method of slowing the spin is to have the wrap around fins pop out in the opposite direction of the bullets spin. This will counter act the spin from the barrel; however, this also does not stop the spin. Finally, another option is to use squibs that would fire shortly after the ECAP leaves the barrel. These squibs would be positioned tangentially around the bullet and would use information from the guidance system to fire in an order that would stop the spin.

2.5 Navigation and Power [E. Chapman]

2.5.1 Methods and Assumptions

It was very important when choosing a device to power the bullet to choose something that would maximize power production using the shortest activation time and a constant power flow rate during the entire time of flight. The size of the device was also very important and eventually became the predominant deciding factor. Therefore, because of the a-fore mentioned factors, thermal batteries were chosen to power the battery. When compared with other ideas such as the use of capacitors or the use a unique DC generator, thermal batteries were best suited to meet power requirements of the bullet within the necessary time frame.

A thermal battery consists of a stack of series cells, in which each cell uses iron disulfide cathodes and lithium alloy cathode. A typical battery has a shelf life of over 20years. The three main mechanisms used to ignite the heat source in a thermal battery are electrical using a squib or match, mechanically using a primer and dynamically using an inertial igniter. Activation can take from 100 milliseconds to a few seconds, delivering watts to kilowatts for periods ranging from minutes to hours depending on battery size. Once activated the battery will rapidly climb to its maximum voltage, which would gradually decline during the remainder of its active life.

It is assumed that the time it will take to ignite the battery and for it to start producing power would coincide with the time the bullet would take to leave the gun barrel.

2.5.2 Results and Discussion

Eagle Picher LLC, one of the leading suppliers of batteries to the military was contacted in order to view their thermal battery catalogs and ultimately to choose a battery. After carefully going through the catalog and looking at the spec sheets of each battery listed there, the CAP-12087 thermal battery was chosen. This battery has a diameter of 34.29 millimeters and a maximum length of 45 millimeters. It has an activation or rise time of 150 milliseconds and a life after ignition of 15 seconds. More importantly, the CAP-12807 can produce 12 volts with a steady current flow of 6 amps, which gives a maximum power available of 72 watts. This battery will operate given it is with a temperature range of 40oF to 131oF and can withstand shock of 10,000g. It has a nominal weight of 71 grams and nominal volume of 1.39 cubed-inches. This battery is ignited mechanically using a primer.

Of all the thermal batteries looked at, the CAP-12087 is best suited to meet the power requirements of the bullet. This battery will provide a fast and efficient way of powering the bullet for the required time of flight. It was quite important to us as a team to choose a method of powering this bullet that could be taken straight off the shelf.

Looking through the Eagle Pichers catalog there were only a few recently dated thermal batteries that could have been possible selections, yet only one, the CAP-12087, that met our requirements. Representatives of Eagle Picher, has said that they do custom make batteries to meet their customers need. Therefore it must be noted that even though it was possible to select a battery from their catalog that met our power requirements, the CAP-12087, is not the only thermal battery that would power this bullet.

2.6 Modeling and Simulation [A. Brewer]

2.6.1 Methods and Assumptions

A major phase of any project is modeling and simulation and the ECAP is no exception. During this phase, the Super Moth was geometrically built and then subjected to rigorous testing in a computer environment to ensure that it would meet the requirements of the CDD. There were two different programs used to simulate the performance of the Super Moth. The primary software package used was PRODAS, which is a 6-degree-of-freedom, high fidelity simulation. All mass properties, aerodynamic coefficients, stability factors and the trajectory data were found using PRODAS. The secondary program, known as cRocket, was used to do further analysis on the trajectory of the Super Moth to ensure that it would hit the target at the three specified points. The cRocket program is only a 3-degree-of-freedom simulation and therefore was only used for trajectory.

Bringing the Super Moth to life in PRODAS started off with building it geometrically. The dimensions of each component were laid out along with their positions in the projectile. Then each component was assigned a material to be made out of so that the total mass and density of the Super Moth could be found using the Mass Properties module of PRODAS. Next the aerodynamics of the Super Moth was found. The FINNER module of PRODAS was used to evaluate the aerodynamics since the Super Moth uses wrap around fins. Once the aerodynamics was found, the stability of the Super Moth was evaluated. A positive static margin was needed in order for the Super Moth to be considered stable. Had the static margin been negative, the Super Moth would not have been dynamically stable enough to make it out of the gun. After the stability was achieved, the trajectory was run to make sure the Super Moth could hit its intended target. The CONTRAJ module of PRODAS was used to set the position, firing time, duration, and thrust of the squibs (thrusters) that the Super Moth uses. The thrust, firing times, and durations for the squibs were manipulated in this phase of simulation, so that the Super Moth would hit its target at the three ranges and altitudes. Acceleration and velocity as well as kinetic energy were studied in this section. Finally the Super Moth was put into the 3-D Visualizer so that an actual flight of the projectile could be evaluated to check the results obtained during the analysis.

The data obtained from the PRODAS simulations were then input into cRocket. The data included mass, Mach number, and coefficient of drag. Then the three specified points were put in and separate runs of the code at each point were made. This was done to check the data from PRODAS and to make sure the Super Moth could hit all three points. The thrust and firing of the squibs could not be input into cRocket, causing a variation in the data.

The major assumption made during the modeling and simulation phase was that the Super Moth was being shot from the Bofors L-70 gun. PRODAS does not have the gun data (rifling, twist, bore) for the MK-3. The gun data was needed for the stability and the trajectory analysis. The L-70 gun data is almost identical to that of the MK-3, which is why it was selected.

2.6.2 Results and Discussion

PRODAS requires several simulations to be performed on the bullet. The first simulation is the mass properties calculations. The total mass of the Super Moth bullet is approximately 1.077 kg. The Super Moth weighs twenty-two percent less than the baseline design.

The second simulation PRODAS performed on the bullet is the aerodynamic analysis. The two most important outputs required from the aerodynamic analysis are the drag and pitching moment of the bullet. The drag (Cx0) is a function of the Mach number and is shown in Figure 1 of Appendix H. The pitching moment (Cma) of a fin is also a function of the Mach number, must be below zero and is shown in Figure 2 of Appendix H. The results obtained for the Super Moth showed an aerodynamically stable bullet.

The third simulation performed on the bullet is the stability analysis. In order for the bullet to make it out of the gun, it must be dynamically stable which means that the static margin must be above zero. The static margin shows whether the center of gravity is in front or behind the center of pressure. The desired position of the center of gravity is in front of the center of pressure. The results from this analysis showed that the Super Moth met the static stability requirements.

The final analysis performed on the bullet is the trajectory analysis known as CONTRAJ in PRODAS. The initial conditions of the temperature, wind and gun error are input here as well as the thruster parameters. Then CONTRAJ is run, outputting a data file at incremented time values. This table includes among others the trajectory, velocity, acceleration, spin, and kinetic energy data. The trajectory coordinates in PRODAS are set as x being downrange position, y being lateral position, and z being vertical position. Positive values for x point downrange, positive values for y point to the left of the bullet, and positive values for z point upwards. The coordinates of the target at the specified downrange positions were obtained from a trajectory file written by Mr. John M. Whyte, a systems engineer at Arrow Tech Associates where PRODAS was developed. Comparing the bullet trajectory data to the target trajectory data showed if the two would intersect at the same time. The CONTRAJ analysis was performed for several combinations of the temperature, wind, and gun error conditions. The three impacts at 500m, 2000m, and 4000m were also analyzed. The Super Moth bullet succeeded in hitting the target at all three positions and all conditions except for one. The bullet could not hit the 500m target at the cold conditions. The bullet came very close, but needed just a little more time to hit the target than was allowed. Further improvement of the bullet design could most likely achieve the 500m target goal at the cold conditions. Overall, the PRODAS results show a successful bullet. The results are included in Table 7, and plots of the trajectory data are included in Figures 8 and 9 as well as Appendix H.

PRODAS Table: 2000 meters at Standard Atmosphere

Initial Conditions

Final

Total Mass

1.077 kg

Total Length

220 mm

Diameter

40 mm

Muzzle Spin Rate

0

CP from Nose

135.6 mm

CG from Nose

123.9 mm

Static Margin

0.29 calibers

Muzzle Jump Factor

0.206 mills/rad/sec

Velocity

1100.0 m/s

614.6 m/s

Kinetic Energy

651.3 kJ

203.3 kJ

Trajectory Angle

10.3 deg

14.2 deg

Time

0 sec

2.52 sec

Total Non-impact Range

0.0 m

2000 m

Altitude

0.00 m

500 m

Slant Range

0.0 m

2063 m

Mach Number

3.23

1.816

Angle of Attack

1.00 deg

0.00 deg

Table 9: PRODAS Results

Figure 10: Z vs Time graph

Figure 11: Y vs Time graph

To verify that the Super Moth would hit the 2000m downrange position, the aerodynamic drag coefficients versus the Mach number were taken from the PRODAS analysis and put into the cRocket code. The cRocket code agreed with the PRODAS results that the bullet would indeed hit the target. The time of flight until impact was different from the PRODAS results. This error is most likely due to the programs use of only three degrees of freedom. The cRocket results are reported in Table 10.

cRocket Table: 2000 m at Standard Conditions

Total Mass

1.0770 kg

Initial Velocity

1100 m/s

Launcher Length

3 m

Launch Angle (los + lead + error) theta

38.284 deg

Time of Flight

1.467 m

Closest Total Approach

0.00 m

Closest Approach in the X Direction

0.00 m

Closest Approach in the Y Direction

0.00 m

Closest Approach in the Z Direction

0.00 m

Table 10: cRocket Results

2.7 Advanced Analysis [C. Ducasse and R. Monery]

2.7.1 Methods and Assumptions

I. Listing of information given

Table 11: Dimensions and performance data

II. Listing of required analysis

2.7.2 Results and Discussion

Figure 12: CFD Model of Thrusters firing

Figure 13: Stress model of bullet

Figure 14: CFD model of flow with Thrusters firing

2.7.3 User Defined

2.8 Launch Platform/ Prototyping [R. Hall]

2.8.1 Methods and Assumptions

The CDD set forth the MK44 weapon system as the baseline gun platform for the ECAP. The launch platform team conducted an extensive internet-based search for other possible 40mm gun systems. Along with the MK44, semi-limited information was obtained on the Bofors L/70 and MK3 weapon systems. The Bofors L/70, MK3, and MK44 systems were each considered as possible launch platforms. After pertinent information was gathered, the three systems were compared in relation to their ability to meet the CDD specifications and the overall best system was selected.

2.8.2 Results and Discussion

The MK3 gun system was selected as the overall best launch platform for the Super Moth. The MK3 is built around a single Bofors L/70 40mm cannon providing a muzzle velocity of 1100m/s and a range of up to 10km. The MK3 can rotate 360o unlimitedly at a velocity of 92 o/sec and can be elevated from 20 o to +80 o at a velocity of 57 o/sec. It is capable of being operated unmanned or being locally controlled from an on-mount operators console.

Figure 15: Bofors MK3

The MK3 is completely covered by a cupola to deflect radar signals and protect it from environmental conditions. The MK3 weapon system has an ammunition magazine capable of holding 101 rounds allowing engagement of a minimum of 10 targets before reloading. It boasts a fire rate of 330rounds/min. It was found that none of the three potential platforms examined provided sufficient rate of fire to meet the maximum objective burst and maximum threshold burst as outlined in the CDD. Hence, two or more cannons must be used in unison to meet fire rate requirements regardless of the particular gun system selected. Two MK3 cannons could provide approximately 10 to 12 rps thus meeting CDD specifications. This will, however, require some modification of the current MK3 system to support two 40mm canons. The only apparent drawback to the MK3 appears to be weight (approximately 3850kg). Due to the systems large size and weight it was decided that mounting the gun system on a trailer would be the most feasible and versatile transportation option. Along with the trailer containing the actual gun system, a separate trailer or vehicle would need to be equipped with the detection radar system and two lasers used for painting the target. The radar and lasers would be powered from the main power supply on the main gun system trailer.

2.9 Trade Studies and Interactions of Subsystems [M. Ray]

2.9.1 Examples of Trade Study Affects on Overall System

Changing one feature of the ECAP system affects the whole of the design. For example, the thruster nozzles must be spatially adjacent to the manifold to maintain efficiency of flow of the exhaust gas. Additionally, the manifold must be adjacent to the exhaust port of the thrust chamber for the same reason. Therefore, there is a sequential nature of the subsystems in the ECAP. Therefore by changing design parameters such as the axial location of the thrust chamber it becomes necessary to change the axial location of the manifold and thruster nozzles. However, the thruster nozzles must be as far to the rear of the bullet as possible in order to maximize the torque they exert on ECAP and minimize interference with the aerodynamics from the flow over the bullet. Also, if the thrusters are moved, they may interfere with the pop out wrap around fins such that they induce roll from the exhaust flow bending around the curved fin. Clearly the features of ECAP are highly dependant on each other.

Another example of how the subsystems of the bullet are dependent is with the lasers used for guidance and the pitch required to intercept the target. The lasers provide the ECAP system with vital information, such as which direction is up. If the pitch is too great the lasers can not illuminate the target and the control system will have no way of orienting itself in order to account for gravity. Therefore the bullet will pitch too low and try to converge on the target through a straight path instead of efficiently modifying its natural ballistic trajectory. By pitching low the actual trajectory would always be low and the ECAP would expend all of its fuel too early so that it will have no fuel left for maneuvering in the end game.

Figure 16: Overall Systems Interaction flowchart

2.9.2 System Integration

Each of the subsystems of the ECAP needs to be incorporated together in order for the system as a whole to work. For example, the ECAP must keep track of the target by inputting the IR laser energy through the pinhole and lens on the nose cone. The photo array senses the IR energy and digitizes it into a matrix, which is sent to the navigation computer. The navigation computer calculates necessary angles, distances, etc. by using known dimensions of the nose cone and photo array specs, as well as theory dealing with centroids, trigonometry, etc. and passes the resulting information in real time to the guidance computer. The guidance computer runs the dynamic control algorithm to ascertain the desired valve states (or proportions). These digital (or analog) data signals are sent to relays (or voltage regulators) as control inputs. The relays control the flow of power from the thermal battery to the manifold. The manifold manipulates the distribution of flow of exhaust gas from the thrust chamber either proportionally or digitally to the four thruster nozzles so that they influence the trajectory of ECAP as desired by the guidance computer. This will hopefully allow the ECAP to hit the target with maximum precision and kinetic energy.

Since ECAP needs to see where the target is, IR laser light must be emitted or reflected off of the target. This IR energy is provided by two lasers in the ground based illumination system. The ground based illumination system needs to know where to direct the mirrors, which directs the laser light, so the ground based target acquisition system can identify the target and calculate the angles from the ground based target acquisition system to the incoming threat. Then the target acquisition system can send the angles to the ground illumination system so it can direct the lasers dynamically so they track on the target. ECAP also needs kinetic energy to reach the target. This kinetic energy is provided and directed by the launch platform. The launch platform also needs to know what direction to point the ECAP initially so it must also receive information (wireless) from the ground based target acquisition system.

Figure 17: Interior Bullet Systems Interaction Flowchart

5.0 Implementation Issues

3.1 Production Cost [T. Lingenfelter]

Component

Estimated Cost ($)

Valve System

50.00

Propellant

10.00

Thermal Battery

100.00

De-spin Ring

25.00

Miscellaneous Wiring

5.00

Fins and Deployment System

120.00

Guidance System

250.00

Manufacturing Costs for Bullet

800.00

Total Cost Per Bullet

1360.00

Table 12: Component Price List for the Super Moth

The major assumption for these prices is that the ECAP bullet will cost above and beyond the cost of a normal bullet for the MK3. Finding individual prices of these items was quite difficult. Most of the companies that were contacted said that they were unable to give the cost of just one part. Most of them bill accordingly as to the quantity that is ordered. For this reason, the numbers in the table are only an estimated cost per item. The Valve System contains all the components for the exiting of the propellant. The Fins and Deployment include the actual material and manufacturing of the fins for the bullet as well as the springs that are used to deploy the fins. The Guidance System price includes the microchip, lens, and clear piece for the nose of the bullet. The Manufacturing Costs are based on the estimate of machining and assembly of all the other components for the bullet. This figure was conceived by allowing eight hours for the machining and assembly at an average cost of $100 per hour. The Total Cost per Bullet is the cost to deliver one bullet for use.

3.2 Manufacturability [C. Steely]

The technology required to manufacture the Super Moth bullet is currently available. The components that have been selected and the materials that have been chosen can easily be purchased and assembled. However, the off-the-shelf components are not the best-fit options, but are the closest options available. Custom built components, including the thermal battery and valves, would need to be made to optimize functionality of the ECAP. The launch system chosen for the bullet is currently available, but will need to be partially modified with the addition of a second barrel and breech. The most difficult part of the manufacturing process for the bullet will be the assembly of the small parts into the small diameter case.

The first step in the manufacturing of the bullet is the fabrication of individual parts. The case of the bullet will start off as a cylindrical piece of steel, which will then be put on a lathe and machined to the final outer diameter and shape. The inside diameters of the case can then be drilled out as well as any holes in the case. The nose of the bullet will start off as a cylindrical piece of tungsten and be placed on a lathe and machined to the desired shape. A slip band made of nylon will be bonded to the outer diameter of the bullet case. The slip band will be made using a molding process. Mounting brackets for attaching the inner parts inside the bullet will also need to be designed and fabricated. All of these parts should be easily and quickly fabricated.

The other parts of the bullet include the seeker system, the guidance computer, the thermal battery, the valves and the thrust nozzles. These parts can all be ordered from an existing manufacturer. The seeker system will consist of several small parts that will need to be assembled into the hollowed section inside of the nose. The thermal battery, valves, thrust nozzles, propellant case, and any other small parts that go inside the bullet, will need to be properly mounted to the case. This will be very difficult considering the small inner diameter of the bullet. Most likely, the best solution for this would be to pre-assemble these parts onto a mounting bracket, connect the wires from the guidance computer, and assemble the entire piece into the bullet as a whole. Once these parts are in place, the nose will need to be attached to the case. The final step in the assembly process will be the attachment of the shell to the rear of the bullet.

The purchase and manufacturing of the individual parts will be relatively easy, considering the required development of the valve system and the customization of a thermal battery, and can be easily and quickly accomplished. However, the assembly of those parts into the bullet will be difficult. The design of the mounts will be very crucial to the proper performance of the bullet. The mounts will need to be very small but will also need to be able to withstand the high g-loads placed on the bullet during firing and maneuvers. Proper seals will need to be achieved between the propellant, thrust nozzles, valves, and case. The surface-finish of the bullet will need to be very smooth and the shape of the bullet very precise in order to minimize drag. Once an assembly process is set up, the manufacturing of the bullet should be relatively quick, easy, and inexpensive.

3.3 Test Schedule [M. Youngblood]

Test Schedule

Year*

1

2

3

4

5

6

7

8

9

10

11

12

Initial Development

Power (battery)

Directional thrust micro-valves

High acc