NANOLAUNCH REACTION CONTROL SYSTEM Final Report

EML 4905 Senior Design Project

A B.S. THESIS PREPARED IN PARTIAL FULFILLMENT OF THE REQUIREMENT FOR THE DEGREE OF BACHELOR OF SCIENCE IN MECHANICAL ENGINEERING

David Dominguez Gianni Jimenez Genesis Vasquez

Advisor: Professor George Dulikravich

November 24, 2014

This B.S. thesis is written in partial fulfillment of the requirements in EML 4905. The contents represent the opinion of the authors and not the Department of Mechanical and Materials Engineering.

ETHICS STATEMENT AND SIGNATURES

The work submitted in this B.S. thesis is solely prepared by a team consisting of David Dominguez, Gianni Jimenez, and Genesis Vasquez and it is original. Excerpts from others’ work have been clearly identified, their work acknowledged within the text and listed in the list of references. All of the engineering drawings, computer programs, formulations, design work, prototype development and testing reported in this document are also original and prepared by the same team of students.

David Dominguez Gianni Jimenez Genesis Vasquez Team Leader Team Member Team Member

Dr. George Dulikravich Faculty Advisor

TABLE OF CONTENTS

ETHICS STATEMENT AND SIGNATURES ...... 1 TABLE OF CONTENTS ...... 2 LIST OF FIGURES ...... 4 LIST OF TABLES ...... 5 ABSTRACT ...... 6 1. INTRODUCTION ...... 7 1.1 PROBLEM STATEMENT ...... 7 1.2 MOTIVATION ...... 9 1.3 LITERATURE SURVEY ...... 10 1.3.1 CUBE SAT ...... 10 1.3.2 NASA’ S NANOLAUNCH PROGRAM ...... 10 1.3.3 ATTITUDE CONTROL ...... 13 1.3.4 TYPES OF ACTUATORS ...... 14 1.3.4.1 MOVEABLE FINS ...... 14 1.3.4.2 THRUST VANES ...... 15 1.3.4.3 GIMBALS ...... 16 1.3.4.4 VERNIER ROCKETS ...... 17 1.3.5 ROTARY VALVES ...... 18 2. PROJECT FORMULATION ...... 19 2.1 PROJECT OBJECTIVES ...... 19 2.2 DESIGN SPECIFICATIONS ...... 20 2.3 ADDRESSING GLOBAL DESIGN ...... 23 2.4 CONSTRAINTS AND OTHER CONSIDERATIONS ...... 24 3. DESIGN ALTERNATIVES...... 26 3.1 OVERVIEW OF CONCEPTUAL DESIGN ...... 26 3.2 DESIGN ALTERNATE 1 ...... 28 3.3 DESIGN ALTERNATE 2 ...... 30 3.4 FINAL PROPOSED DESIGN ...... 32 3.4.1 MANIFOLD ...... 32 3.4.2 VALVE ...... 33 3.4.3 STEPPER MOTOR ...... 35 3.4.4 ON/O FF VALVE ...... 36 3.4.5 RCS CONTROLLER ...... 36 3.4.6 ASSEMBLY ...... 37 3.5 PRODUCTION OPTIONS ...... 38 3.5.1 TRADITIONAL MACHINING ...... 38 3.5.2 3D PRINTING ...... 38 4. PROJECT MANAGEMENT ...... 41 4.1 OVERVIEW ...... 41 4.2 GANTT CHART FOR THE ORGANIZATION OF WORK AND TIMELINE ...... 41 4.3 BREAKDOWN OF RESPONSIBILITIES AMONG TEAM MEMBERS ...... 41 4.4 POTENTIAL FOR COMPETITION ...... 42 5. ENGINEERING DESIGN AND ANALYSIS ...... 43 5.1 OVERVIEW ...... 43

5.2 ENGINEERING CALCULATIONS ...... 43 5.3 STRESS AND PRESSURE SIMULATIONS ...... 46 5.4 COST ANALYSIS ...... 48 6. PROTOTYPE CONSTRUCTION ...... 49 6.1 PROTOTYPE SYSTEM DESCRIPTION ...... 49 6.2 COMPLETED PROTOTYPE DESIGN ...... 50 6.2.1 VALVE AND MANIFOLD ...... 51 6.2.2 PIPING ARANGEMENT ...... 51 6.2.3 TESTING APPARATUS ...... 52 6.3 PARTS LIST ...... 55 6.4 PROTOTYPE COST ANALYSIS ...... 56 7. TESTING AND EVALUATION ...... 58 7.1 OVERVIEW ...... 58 7.2 DESIGN OF EXPERIMENTS ...... 60 7.3 TEST RESULTS AND DATA ...... 61 8. DESIGN CONSIDERATIONS ...... 62 8.1 ASSEMBLY ...... 62 8.2 DISASSEMBLY AND MAINTENANCE ...... 62 8.3 ENVIRONMENTAL IMPACT ...... 63 8.4 RISK ASSESSMENT ...... 64 9. DESIGN EXPERIENCE ...... 65 9.1 OVERVIEW ...... 65 9.2 STANDARDS USED IN THE PROJECT ...... 65 9.3 IMPACT OF DESIGN IN A GLOBAL AND SOCIETAL CONTEXT ...... 66 9.4 PROFESSIONAL AND ETHICAL RESPONSIBILITY ...... 66 9.5 LIFE -LONG LEARNING EXPERIENCE ...... 67 10. CONCLUSION ...... 68 10.1 CONCLUSION AND DISCUSSION ...... 68 10.2 COMMERCIALIZATION PROSPECTS OF THE PRODUCT ...... 68 10.3 FUTURE WORK ...... 69 11. REFERENCES ...... 71 12. IMAGE CREDITS ...... 73 13. APPENDICES ...... 74 13.1 APPENDIX A: DRAWINGS ...... 74 13.2 APPENDIX B: PROOF OF PROJECT PRODUCTION STATUS ...... 76 13.3 APPENDIX C: ORIGINAL SWAGELOK QUOTE ...... 77 13.4 APPENDIX D: STANDARDS , CODES , SPECIFICATIONS AND TECHNICAL REGULATIONS ...... 79 13.5 APPENDIX E: RAW DATA FROM VOLUMETRIC FLOW EXPERIMENT ...... 80

LIST OF FIGURES

Figure 1 – Picture of the 3U Gene Sat 1 and the Mark II P-POD (17) ...... 10 Figure 2 – Comparison of Traditional Launch Vehicle with the Nanolaunch Vehicle ...... 12 Figure 3 – Movable Fin Illustration ...... 14 Figure 4 – Thrust Vane Illustration ...... 15 Figure 5 – Gimbaled Thrust Illustration ...... 16 Figure 6 – Vernier Rocket Illustration ...... 17 Figure 7 – Diagram of a rotary valve commonly used in brass instruments (19) ...... 18 Figure 8 – Nanolaunch Program Expected RCS Activation Points ...... 19 Figure 9 – RCS location within Nanolaunch vehicle ...... 20 Figure 10 – RCS location and space under shroud for propellant tanks ...... 21 Figure 11 – Mockup of rocket stages ...... 21 Figure 12 – NASA-Proposed RCS Version 1 ...... 24 Figure 13 – NASA-Proposed RCS Version 2 (Roll Test) ...... 25 Figure 14 – Rotating Valve System (Manifold) ...... 26 Figure 15 – Rotary valve (solid grey) that provides 4 different exit combinations ...... 27 Figure 16 – Rocket cross section showing required firing combinations ...... 27 Figure 17 – Exploded view of the parts ...... 28 Figure 18 – Rendered model shown in 3D printed enclosure ...... 29 Figure 19 – 3D print of the valve made at NASA ...... 29 Figure 20 – Second design ...... 30 Figure 21 – Flow analysis in SolidWorks ...... 31 Figure 22 – Current RCS Manifold Design ...... 32 Figure 23 – Current RCS Valve Design ...... 33 Figure 24 – Current RCS Assembly Design ...... 34 Figure 25 – Current Stepper Motor Model ...... 35 Figure 26 – Current RCS Switch Valve ...... 36 Figure 27 – Complete RCS Assembly Design ...... 37 Figure 28 – Prototype Tolerances ...... 39 Figure 29 – Manifold showing 0.015" step for valve seal ...... 40 Figure 30 – Projected project timeline chart ...... 41 Figure 31 – Stress analysis on rotary valve ...... 46 Figure 32 – Pressure simulation for valve channel ...... 47 Figure 33 – The three prototypes together ...... 50 Figure 34 – Assembled Prototype ...... 50 Figure 35 – Final Test Setup ...... 53 Figure 36 – Testing with tank and servo control ...... 54 Figure 37 – Current NASA RCS Prototype ...... 59 Figure 38 – Compressed Air Tank Warning Label ...... 64 Figure 39 – Weld-ready valve on the left ...... 69 Figure 40 – Various types of on/off valves that could be used ...... 70 Figure 41 – Shapeways Receipt ...... 76

LIST OF TABLES

Table 1 – Minor Loss Coefficients ...... 45 Table 2 – Complete List of Parts Used ...... 55 Table 3 – Complete List of Parts Purchased ...... 57 Table 4 – Volumetric Flow Rate Experimental Data...... 80

ABSTRACT

This project involves the design, analysis, manufacture, and testing of a reaction control system (RCS) for an orbital launch vehicle suitable for NASA’s Nanolaunch program. The goal of the project is a cheap, reliable RCS that will help lower the cost of entry into space experimentation for universities. Our design reduces the number of failure modes of the baseline

NASA RCS design, and is half the weight at one-third the cost.

1. INTRODUCTION

1.1 PROBLEM STATEMENT

The goal of our project is to develop a reaction control system (RCS) that reduces cost, mass, volume, and complexity as compared with existing designs, in order to open up space experimentation to a larger number of universities. NASA’s baseline RCS design for launch vehicles developed under the Nanolaunch program uses four on/off solenoid switches with various pipe adapters to control four cold gas (CO 2) thrusters. The proposed design uses a single selector valve and one solenoid switch. The selector valve will be controlled by a stepper motor, which will align the ports needed for proper RCS operation. Pitch, yaw, and bi-directional rotation will be possible with the current port combination. The RCS was designed with

SolidWorks and will be analyzed with SolidWorks Flow Simulator, ANSYS, and other software as resources become available.

A prototype was 3D printed out of 540 stainless steel and tested with compressed air.

Once the concept has been proven, the RCS manifold and valve will be 3D printed in titanium using fabrication resources at NASA Marwill Space Flight Center (MSFC) to be used with a carbon fiber 4500 PSI tank regulated down to 1150 PSI (31 MPa to 8 MPa). The required force per RCS activation is currently set at 2.25-3.37 lbf (10-15 N). The theoretical calculations for our design estimate 28 lbf (125 N) with an 1150 PSI (7.6 MPa) regulator using ¼” ID tubing, and

18.4 lbf (82 N) using our 750 PSI (5 MPa) test tank. Our estimation assumes half the regulator pressure at the nozzles. This allows flexibility in the event of requirement changes, flow losses, and other unknown effects.

Our concept eliminates the heavy pipe adapter fittings, reduces the failure points due to the elimination of pipe connection points and solenoid switches, and reduces the cost of parts.

The incorporation of our design into a future Nanolaunch vehicle will enable NASA to meet their budget requirements and offer universities affordable access to space for their orbital experiments.

1.2 MOTIVATION

Conceived as a skunkworks project at MSFC, interest in the Nanolaunch program has grown among center management as well as NASA engineers, gaining the program more funding and manpower over the last year. Recently, NASA has made Nanolaunch an official, fully funded technology development program with dedicated full-time employees. As part of the Nanolaunch program, NASA encourages collaboration with academia by allowing universities to submit ideas for various launch vehicle subsystems, which may be incorporated into the system design if proven to meet vehicle requirements at minimal cost.

In order to design an effective low-cost RCS, it is first essential to become familiar with the program requirements for which the system will be designed. In addition, it is necessary to analyze current and historical methods of controlling the translation and attitude of spacecraft.

Finally, different technologies will be analyzed for potential use in this application.

1.3 LITERATURE SURVEY

1.3.1 CUBE SAT

The CubeSat standard was designed to standardize the size and shape of nanosatellites sent into orbit for ease of cargo bay space allotments and launch mechanism design. (1) A standard CubeSat measures 10x10x10 cm (3.93 in 3), weighs no more than 1.33 kg (2.93 lbs) and

is called a “1U” CubeSat. CubeSats dimensions can be increased in 1U increments, allowing for

the launch of 2U (20x10x10 cm) and 3U (30x10x10 cm) modules.

The Poly-Picosatellite Orbital Deployer (P-POD) was designed to carry and launch 3U or

6U CubeSat units from a spacecraft. Any CubeSat project will require that the launch craft be

fitted with a P-POD.

Figure 1 – Picture of the 3U Gene Sat 1 and the Mark II P-POD (17)

1.3.2 NASA’ S NANOLAUNCH PROGRAM

NASA’s Nanolaunch program is designed to make space more accessible to governmental, commercial, academic, and research entities by lowering the cost of launches.

(NASA, n.d.) Currently, sending an experiment module into space requires finding a spacecraft scheduled for future launch that has enough payload space and has the right components to launch the module at the correct altitude (usually with the P-POD system). Finding a launch vehicle that meets these requirements is difficult, and is further complicated by the high costs of launching. For example, the current average cost to launch a 1U CubeSat with an independent launch agency is $100,000 to $125,000. (1)

For the academic community, timing is a critical issue since the delay of an experiment launch can delay the graduation of students whose research thesis depends on the results. For this reason, NASA initiatives dedicated solely to the launching of CubeSats are considered preferable to cheaper, less reliable commercial alternatives. The Educational Launch of Nanosatellites

(ELaNa) project, for example, is tailored primarily for the delivery of academic CubeSATS. (3)

However, the high price of the launches means that relatively few of them are sent off each year.

The Nanolaunch initiative seeks to increase the number of launches available for CubeSats by reducing this prohibitively high cost.

Figure 2 – Comparison of Traditional Launch Vehicle with the Nanolaunch Vehicle

1.3.3 ATTITUDE CONTROL

When discussing spacecraft, the word “attitude” refers to the vehicle’s orientation in space. In order to control attitude, the craft first requires sensors that can be used to determine the current orientation. Once it has determined its current position and the position it needs to attain for the next part of the mission, computer algorithms can then calculate how to effectuate this change in attitude. This is then carried out by the use of actuators, which apply force and/or torque to move the vehicle. Together, these components make up the guidance, navigation and control system (GN&C) of a spacecraft. (5) The scope of our project concentrates on the actuator portion of this system, to be designed specifically for the requirements of NASA’s Nanolaunch program.

1.3.4 TYPES OF ACTUATORS

The development of rockets in the 20th century led to many innovations in improving rocket stability and in reducing its weight. Previous methods of ensuring a rocket’s stability, such as bent fins that caused rockets to spin rapidly and stabilize (thereby increasing drag), were abandoned in favor of active controls, which use the intelligence of a computer to actuate a vehicle in a precise and efficient manner. (7)

1.3.4.1 MOVEABLE FINS

In order to redirect a rocket or air-to-air missile, moveable fins can change the amount of aerodynamic force by deflecting in the desired direction. The resultant opposing torque around the rocket’s center of pressure will cause it to turn in the desired way, similar to a rudder. (18)

Figure 3 – Movable Fin Illustration

1.3.4.2 THRUST VANES

Thrust vanes are mobile fins placed in the engine that can tilt to deflect the exhaust leaving the rocket’s engine, and this action causes its nose to turn the opposite way, redirecting the rocket’s flight path. This was used on the V2 and Redstone rockets, but is not currently in use. (18)

Figure 4 – Thrust Vane Illustration

1.3.4.3 GIMBALS

Rockets using gimbals for reaction control have the exit nozzle from the engine free to rotate, allowing it to redirect the engine’s thrust as needed. Most modern full-size rockets utilize this method to control and stabilize their course. (18) This system is extremely complex and expensive.

Figure 5 – Gimbaled Thrust Illustration

1.3.4.4 VERNIER ROCKETS

Vernier rockets are small rockets attached to the outside or bottom of the spacecraft and angled to produce torque. They fire to change the course of the vehicle- firing one will change the direction by rotating the craft while firing two at a time will cause translation. This is mostly in use only on older craft, as this requires plenty of additional fuel and plumbing in order to function, and therefore plenty of additional weight is required. (18)

Figure 6 – Vernier Rocket Illustration

For this technology to be viable for use in a smaller craft, the plumbing required would have to be severely reduced.

1.3.5 ROTARY VALVES

Rotary valves change the paths of fluid flow that traverse them by rotating to close or open passageways. This allows one part to stop, reduce, and change the path of airflow or fluid flow, depending on the position of the transverse plug. Rotary valves are commonly used to change the pitch of brass instruments, to control the steam and exhaust of a steam engine, to move fluids in two chambers at different pressure levels, and to function as a measuring or metering device for the distribution of drugs or other materials. (10)

Figure 7 – Diagram of a rotary valve commonly used in brass instruments (19)

The simple rotational motion of the rotary valve allows for its operation via stepper motor, permitting very accurate and quick transitions. This would be ideal for the redirection of gas into Vernier rockets for the attitude control of a small spacecraft due to its versatility and durability.

2. PROJECT FORMULATION

2.1 PROJECT OBJECTIVES

Requirements for the RCS system are as follows:

a. The reaction control system will fit in a cylindrical body with the following

measurements: Diameter of 8 inches (20.3 cm) and length of 24 inches (60.9 cm).

b. Logos: NASA’s official logo will be used when presenting posters, papers, and on the

final build. No written permission was granted, but the project was advised and approved

by David Dominguez’s internship advisor in 2013 to proceed with David’s idea of a

rotary valve system for the senior design course.

c. Testing: The working prototype will be completed within two months of the start of the

semester, at which point we will begin testing, complying with NASA testing codes for

safety.

Figure 8 – Nanolaunch Program Expected RCS Activation Points

2.2 DESIGN SPECIFICATIONS

The RCS must fit within the designated space in the vehicle, and all components must be able to withstand the force of the pressurized gas. The RCS must also be securely anchored to the craft in order to rotate it as needed. The current planned location for the RCS can be seen below in Figure 9. The figure shows the third, fourth, and fifth stages, along with the payload. It will be in this configuration that the RCS will first activate. The weight of the vehicle at this stage is approximately 1100 pounds (500 kg).

Figure 9 – RCS location within Nanolaunch vehicle

Figure 10 shows the vehicle with the shroud in place. Transparency has been applied to the shroud to gauge the volume allotment for the RCS system. The tanks containing the pressurized gas will fit between the upper stages and the shroud. The diameters of the shroud and

fourth stage are 18 and 10 inches respectively (45.7 and 25.4 cm). This provides for approximately 3.5 inch (8.9 cm) wide ring around the fourth stage for tanks.

Figure 10 – RCS location and space under shroud for propellant tanks

Figure 11 shows a full-scale mock-up of the last two stages. The stands for the stages are measured for the purpose of showing the distance to the shroud.

Figure 11 – Mockup of rocket stages

The specific placement of the RCS valve and associated tubing is still to be determined by NASA. The exhaust nozzles will be placed as close to the shroud as allowable for a larger moment arm and thus more effective control. An extendable system is also possible. Once the shroud is ejected, arms can extend to rotate the RCS tubing to a wider position and lock in place, thereby increasing the torque even more.

2.3 ADDRESSING GLOBAL DESIGN

Due to the economical nature of the proposed RCS, the successful use of this design in

Nanolaunch missions may lead to future use on similar initiatives by foreign space agencies.

Apart from NASA, there are twelve other space agencies currently capable of launches, including the European Space Agency (ESA), the French National Center of Space Research

(CNES), the Russian Federal Space Agency (RFSA), and the China National Space

Administration (CNSA). Recognizing this, all dimensions in this report have been given in both imperial and metric units for the convenience of the reader.

2.4 CONSTRAINTS AND OTHER CONSIDERATIONS

The goal of this project is to create a more economical RCS than the current prototype

that has been developed at NASA while maintaining the same level of functionality and

reliability. For the project to be considered successful, the completed prototype must be able to

perform the same roll, pitch, and yaw functions at a fraction of the current cost.

NASA engineers are currently using one on/off valve for each of the four thrusters on

their RCS design. This design is heavier due to the tube interfaces; is more prone to failure with

four times the chance of a valve failing, (not including the additional chances of failure due to

the extra interfaces); and costs four times as much as our proposed design. Each on/off valve

costs $363 on its own.

Figure 12 – NASA-Proposed RCS Version 1

Figure 13 – NASA-Proposed RCS Version 2 (Roll Test)

3. DESIGN ALTERNATIVES

3.1 OVERVIEW OF CONCEPTUAL DESIGN

Our proposed system consists of a rotating valve (shown in solid yellow in Figure 14) within a manifold. The valve will be rotated by a stepper motor to align the ports according to the desired thrust mechanics. An on/off valve will then open briefly to pulse the high-pressure cold gas through the nozzles to roll or pitch the vehicle. The rotary valve was designed to have four different combinations for the exit nozzles that will control the rocket after Phase 1 of the launch. This can be seen in Figures 11-13.

Out Out

Figure 14 – Rotating Valve System (Manifold)

Figure 15 – Rotary valve (solid grey) that provides 4 different exit combinations

Figure 16 shows the combinations of thruster firing (numbered arrows outside the circles) and the effect of the firing (orange arrows inside circles). The left two are the two possible roll directions and the right two are the pitch directions. For yaw, the vehicle rolls to one side and then a pitch combination is used.

Figure 16 – Rocket cross section showing required firing combinations

3.2 DESIGN ALTERNATE 1

Our first design of the RCS valve itself consisted of 19 parts, as seen in Figure 17 below.

Gas would flow into the manifold through an off-center port on the top. Channels in the rotating valve would funnel the gas into two orifices that would expel the gas through the desired exit ports. The flow diameter was only 1/8”.

Figure 17 – Exploded view of the parts

Figure 18 shows this first design of the RCS valve system installed in an 8-inch (20.3 cm)

3D-printed fuselage with built in nozzles, for mounting on a test vehicle consisting of a Wildman

Ultimate Class III amateur rocket.

Figure 18 – Rendered model shown in 3D printed enclosure

The valve was 3D printed by NASA in March 2014 to have a physical prototype to help analyze the design. The print was not high resolution enough to allow for proper fit and seal of the parts.

Figure 19 – 3D print of the valve made at NASA

3.3 DESIGN ALTERNATE 2

Our second design increased the flow diameter to 1/4” (.635 cm) which greatly increased the force of the RCS. It was 3D-printed by a Makerbot at Florida International University’s

Engineering Manufacturing Center (FIU EMC). This valve was 2.9” (7.4 cm) in diameter and

1.75” (4.4 cm) tall.

Figure 20 – Second design

An initial simple flow analysis was done with the second design in SolidWorks to ensure the gas would flow out of both ports equally in a vacuum. This flow simulation can be seen in

Figure 18.

Figure 21 – Flow analysis in SolidWorks

3.4 FINAL PROPOSED DESIGN

3.4.1 MANIFOLD

The purpose of the manifold is to hold the valve system in position (four-bolt mount) and to provide a point of entry for the compressed cold gas and multiple points of exit for proper nozzle firing.

Figure 22 – Current RCS Manifold Design

The final manifold will be 3D printed in titanium using the laser sintering method at

NASA’s Marwill Space Flight Center. The ports and walls of the manifold will withstand a 1600

PSI cold gas pressure which includes a 1.5 safety factor. It will be anchored to the inner fuselage of the rocket with four #4-40 steel hex bolts. The baseline manifold is 1.9 inches (4.8 cm) in diameter and 1.375 inches (3.5 cm) tall and weighs 1.3 pounds (.58 kg).

3.4.2 VALVE

Figure 23 – Current RCS Valve Design

The valve will provide one entry and two exit points for the cold gas. It will move freely within the manifold and direct the pressure to the proper nozzle ports. It will be oriented within the manifold by means of a shaft attached to a stepper motor when unpressurized. The valve will also be 3D printed in titanium.

The valve will be held onto the manifold with a stainless steel thrust bearing and a CNC milled G10 plate as shown in Figure 24.

Figure 24 – Current RCS Assembly Design

3.4.3 STEPPER MOTOR

The stepper motor will be a standard NEMA 17 motor. It will be directly connected to the valve with set screws. The stepper motor will receive power from a

12-volt regulator and stepping controls from a stepper motor driver purchased from Pololu. Input from the flight controller will be used to control the motor driver to align the valve with the proper ports.

Figure 25 – Current Stepper Motor Model

3.4.4 ON/OFF VALVE

The on/off valve will open to enable the flow of 750 PSI (5.171 MPa) of cold gas once

given the signal from the flight controller. A Parker Series 9 solenoid valve is used with a

maximum operating pressure of 1250 PSI (8.618 MPa) and a cycling speed of less than 5 ms.

Figure 26 – Current RCS Switch Valve

3.4.5 RCS CONTROLLER

The RCS controller is a circuit that will control both the stepper motor and the on/off valve. It will receive input from the inertial measurement unit and decide the proper outputs based on the flight profile programmed before flight. This aspect is beyond the scope of this project as NASA has not finalized the details of the flight profile and RCS activations.

3.4.6 ASSEMBLY

The assembly of the RCS mechanism is shown below. 3/8 inch OD, 1/4 inch ID stainless steel tubing will be used to connect the Swagelok fittings to the ports.

Figure 27 – Complete RCS Assembly Design

3.5 PRODUCTION OPTIONS

3.5.1 TRADITIONAL MACHINING

Initial plans centered on machining the valve and manifold. The purpose was to achieve the most accurate construction with the tight tolerance control available through the use of lathes and mills. Transparent acrylic was chosen for the manifold’s material in order to troubleshoot the valve movement if needed. The valve itself would be carved out of Delrin for improved structural integrity.

The CAD models were designed for this method of construction, converted into drawings and sent to FIU’s Engineering Manufacturing Center for a quote. The quote for both parts came in at 12 hours of labor for $475 for both the manifold and valve. While this is a great price for the amount of labor required, the team sought to find a more economical solution.

3.5.2 3D PRINTING

Sending the same CAD models to the 3D printing company, Shapeways, yielded a more agreeable $171 price for the set printed in stainless steel. However, while cheaper, the parts require finishing. The accuracy the 3D printer is high, but still far lower than that of mills and lathes. This means that some additional work is required to get the parts to fit properly. The tapping of all screw holes is also required.

FIU’s Engineering Manufacturing Center was consulted to ascertain the viability of a 3D printed set. A favorable recommendation was given for 3D printing in stainless steel and the part was ordered. Although the part was received within 2 weeks of the order (which is the same turn- around time as the milling), the required finishing will add to the time and cost. Once the part

was received, lathe work was done at FIU’s Engineering Manufacturing Center which ensured the proper fit and function of the rotary valve system.

Tolerancing was mentioned in the previous traditional machining section as a benefit associated with that method. 3D-printing doesn’t have the accuracy of milling and so the tolerances are of particular concern. To visualize this concept, Figure 23 shows the tight tolerance required for the valve seals to function correctly. The difference between the diameters of A and B as shown in the figure is only 0.014” (0.36 mm). This is to allow the O-ring to fit and seal the bottom portion of the valve. Our tolerance values for the two diameters are

+0.005/-0.000” (+0.127 mm) for the upper portion and +0.000/-0.005”

(-0.127 mm) for the lower portion. Point C shows the small tolerance allowed for O-ring clearance with the smaller diameter of the manifold. If the O-ring hits the edge, it could possibly tear.

Figure 28 – Prototype Tolerances

Figure 29 shows the end result of the tight tolerance milled out for the O-ring seal. The picture shows an exact 0.715” diameter and an exact 0.700” diameter milled with a lathe. The

0.700” section is the seat for the top of the valve and allows it to spin freely while maintaining its axial position. The 0.715” portion allows room for the O-ring to be inserted.

Figure 29 – Manifold showing 0.015" step for valve seal

It is important to note that 3D printed parts that require tight tolerances should be designed with enough extra material to allow for material removal on a mill and/or lathe in order to bring it into proper tolerances. For 3D printing in steel, a minimum of 0.03” should be added to all surfaces requiring tight tolerances to allow for machining to those tolerances.

4. PROJECT MANAGEMENT

4.1 OVERVIEW

Performing all the analysis, procuring all of the necessary parts, assembling the RCS prototype and testing it will all take time, therefore, it is essential to divide up the time available and the tasks required effectively.

4.2 GANTT CHART FOR THE ORGANIZATION OF WORK AND TIMELINE

January February March April May June July August September October November December Project Discussion Research Computer Modeling Cost Analysis Poster Design Material Selection Manufacturing Testing Analyze Data Final Presentation Figure 30 – Projected project timeline chart

4.3 BREAKDOWN OF RESPONSIBILITIES AMONG TEAM MEMBERS

• David Dominguez: CAD design, manufacturing, testing, NASA contact

• Gianni Jimenez: CAD design, manufacturing, testing, dynamic analysis

• Genesis Vasquez: Manufacturing, flow simulations, dynamic analysis

4.4 POTENTIAL FOR COMPETITION

This design is new and unique. While rotary feeders exist that use rotary valves to

transport gases, there has not yet been any documented use of a rotary valve for use in an

actuation control mechanism. (11)(12) There is no need to compete with other universities, as

our only task is to prove whether such system will be feasible for NASA’s Nanolaunch program.

5. ENGINEERING DESIGN AND ANALYSIS

5.1 OVERVIEW

For the RCS to be functional, it needs to effectively direct the pressurized gas to rotate the rocket. This means that the gas pressure and velocity at the end of the piping system should be calculated in order to find whether or not this will fulfill the requirements. However, these values cannot be found without the necessary initial values, which can only be found experimentally. Therefore, the following engineering calculations use the test data from Section

7.3 - Test Results and Data. The equations used in these calculations were found in

Fundamentals of Fluid Mechanics 7 th Edition . (13)

5.2 ENGINEERING CALCULATIONS

The start of any fluid dynamics calculation first requires the calculation of the flow’s

Reynolds number in order to determine whether the flow is laminar, turbulent, or in between.

The properties of air are as follows:

kg ρ = 1.22 m

kgS μ = 1.85x10 m The inlet velocity was calculated as described in Section 7.3 - Test Results and Data by comparing the volumetric flow rate with time and the volume of air.

m V = 154.22 s

The cross-sectional area of the inlet pipe is D = 0.00635 m, which means that the area,

A = 0.00635 m 2. With these values, the Reynolds number can now be calculated.

ρVD . ∗ . ∗ . Re = = = 64,580.7 μ . The next step is to find the inlet pressure:

. ∗. = P = = 14507.6 = 14.5 In order to find the outlet velocity, the major and minor losses are first ignored.

Q1 = Q 2 + Q 3

Q1 = A 2V2 + A 3V3

V3 = V 2 = = 77.109 m/s ∗ Now the major and minor losses can be taken into account in order to find a more realistic value for the outlet velocity.

p V p V l V + + Z = + + Z + f + ΣK γ 2g γ 2g D 2g First, the major losses were found. Major losses are due to friction in the pipe, though this factor is expected to be small compared to the minor losses due to the relative shortness of the piping involved.

(Eq. 8.34) (13) h = f

= 0.6096m D = 0.00635 m The equivalent roughness value used was that of a commercial steel pipe: ε = 4.5e-5 m.

(Table 8.1) (13)

The Re & relative roughness on Moody’s Chart (Figure 8.20) (13) were used to approximate the friction factor, = 0.035 . The minor losses were then calculated.

(Eq. 8.36) (13) h = ΣK The following parts and their associated loss factor coefficients were found in Table 8.2:

Table 1 – Minor Loss Coefficients Part Quantity Associated Loss

90˚ Threaded Elbows 3 = 3 ∗ 1.5 = 4.5 Tee Branched Flow, Threaded 1 = 2.0 45˚ Flanged Elbows 2 = 2 ∗ 0.2 = 0.4

Afterwards, Bernoulli’s equation can be used to find the major and minor head loss, as long as we assume that there is no significant change in height and that the compressed air exits into the atmosphere:

Z1 = Z 2 = 0 P2 = 0 γ = 11.81

p V V l V + = + f + ΣK γ 2g 2g D 2g

. . + = [ + .∗. + . ]* V . ∗. ∗. .∗∗. ∗.

= 65.20/ Therefore, the exit velocity was found to be 65.50 m/s.

5.3 STRESS AND PRESSURE SIMULATIONS

Part of the manufacturing process involves testing the materials for the custom RCS.

Before any physical testing was performed, simulations were done to ensure that the critical

components of the RCS would not fail during operation. An additional pressure change analysis

is currently underway.

The figure below shows the stress analysis conducted on the valve, and the results show

that the desired pressure for successful control, 300 psi, will not affect the strength of the

material (Delrin 100) while in action.

Figure 31 – Stress analysis on rotary valve

Because our valve was designed with a 90° bend to supply the exit ports, some loss in pressure will be inevitable. Our initial assumption of 300 PSI will not satisfy the required force per exit nozzle to orient the rocket at the desired attitude. According to our simulations, higher inlet pressures will need to be calculated to satisfy the mission requirements of 9 lbf (40 N) per nozzle.

Figure 32 – Pressure simulation for valve channel

5.4 COST ANALYSIS

Rapid prototyping the RCS in titanium by selective laser melting (SLM) was estimated by NASA to cost $413.74. The NEMA 17 stepper motor required to turn the rotary valve will cost $24.95. The input valve, as previously mentioned, will cost $363. The Swagelok piping is estimated to cost around $150. A scuba tank system is currently owned by one of the team members, saving the cost of purchasing a new one. This leaves the current running total as

$951.69 at the current design iteration. Future changes to the design, however, will increase the cost, since the new pieces will have to be produced.

6. PROTOTYPE CONSTRUCTION

6.1 PROTOTYPE SYSTEM DESCRIPTION

The prototype system will consist of:

• 540 Steel 3D printed valve and manifold assembly

• Swagelok pipe fittings

• Swagelok 0.245 inch ID pipes

• 750 PSI supply from paintball gun tank system

• NEMA 17 motor for turning the valve

The system will be connected to a 3D printed shroud to provide support and ports for the tubes coming out of the manifold. This system will then be hung vertically to test the translational and rotational effects of the RCS. Thrust capacity will be measured while the system is fixed on a scale and compared to the angular maximum reached during the vertical hang testing.

6.2 COMPLETED PROTOTYPE DESIGN

Figure 33 shows all three prototypes of the valve; the right-most being the current one.

The current design maintains the ¼” flow diameter but decreases the diameter to 1.9” and height to 1.375”. The current prototype is 3D printed in 540 steel.

Figure 33 – The three prototypes together

The current prototype setup can be seen below.

Figure 34 – Assembled Prototype

6.2.1 VALVE AND MANIFOLD

Two gas delivery systems are tested. The first uses ¼” OD piping from the tank to the

Parker Series 9 on/off solenoid valve. Although the ID of the pipe is 0.142” (half our desired size), it has to pass through the 1/32” orifice of the Parker valve which becomes a bottleneck.

The second gas delivery system consists of ¼” ID tubing throughout, but without an on/off valve, thereby eliminating the 1/32” orifice bottleneck. The tank will be turned on and off manually for this test. This is to measure the output capable when suitable flow control is acquired, since valves capable of controlling this volume are priced beyond the funding limit of this project.

6.2.2 PIPING ARANGEMENT

The pipes purpose is to get the air pressure from the tank to the on/off valve, from the on/off valve to the RCS valve, and then from the RCS valve to the exterior of the craft. For our tests, the pipe routing is as simple as possible with the simple purpose of allowing us to test air flow through the RCS valve. The actual routing system on the Nanolaunch will be determined once the vehicle is further along in the design process.

6.2.3 TESTING APPARATUS

Our current testing device consists of a direct flow of air from the tank to the RCS valve.

The RCS valve, air tank, stepper motor, and a potentiometer are mounted on aluminum

C-channel which is, in turn, mounted on an aluminum shaft with pillow bearings to allow rotation. When the tank is opened, the RCS system rotates on the shaft. The potentiometer is included to provide a feedback loop signal on the position of the valve.

An Arduino Uno controls the position of the valve using the potentiometer value. It then sends a control signal to a stepper motor driver to turn the valve until the potentiometer signal returns the desired value. The stepper motor is powered by a 12V regulator, and both the

Arduino and the stepper driver are powered by a 5V regulator. This testing device is being further developed to include the on/off valve, steel piping, tank straps, on-board electronics, and a battery.

Figure 35 – Final Test Setup

Figure 36 – Testing with tank and servo control

6.3 PARTS LIST

Table 2 – Complete List of Parts Used

Quantity Part Supplier Cost 1 DRV8825 Stepper Motor Driver Pololu $ 8.95 2 Pololu Stamped Aluminum L-Bracket Pololu $ 7.90 1 NEMA 17 Stepper Motor Amazon $ 16.70 1 DC-DC 12v Step down converter Amazon $ 7.95 1 3/8-24 to 1/4" NPT SS Adapter Amazon $ 19.95 1 3/8" Tube x 1/4" NPT Ebay $ 8.25 1 1/4" Tube x 1/8" NPT Ebay $ 7.95 1 3/8" OD Steel Tube Ebay $ 12.86 1 3/8" Tube x 1/4" NPT Ebay $ 7.95 1 1/4" OD Steel Tube Ebay $ 4.98 4 3/8" Tube x 1/4" NPT 90 Bend Ebay $ 35.80 1 3/8" Tube x 1/4" NPT Ebay $ 8.25 1 1/4-18 NPT Tap Ebay $ 27.00 1 12mm OD 6mm ID Steel Thrust Bearing McMaster-Carr $ 16.01 1 1/4 inch x 2.00 inch D-Shaft Servocity $ 1.49 1 1 inch Smooth Hub Servocity $ 5.99 1 3/8 inch Bore Parallel Tube Clamp Servocity $ 5.99 1 Surface Mount Adaptor A Servocity $ 3.99 1 3 inch ID x 1/8 inch Smooth Belt Servocity $ 0.59 1 2.5 inch ID x 1/8 inch Smooth Belt Servocity $ 0.49 1 3.5 inch ID x 1/8 inch Smooth Belt Servocity $ 0.69 1 Single Header Row Pins Servocity $ 1.49 1 Dual Screw Plate (2 pack) Servocity $ 2.99 4 4-40x1/4 inch Flat Head Screws Servocity $ 0.12 4 6-32x1/4 inch Flat Head Screws Servocity $ 0.15 4 4-40x5/16 inch Socket Head Screws Servocity $ 0.35 4 4-40x3/8 inch Socket Head Screws Servocity $ 0.35 1 Crossover Plate A Servocity $ 5.99 1 1/4 inch to 5mm Set Screw Shaft Coupler Servocity $ 4.99 2 Rubber Edge Trim Servocity $ 0.89 1 Shipping Servocity $ 6.99 1 48 CU Compressed Air Tank Splat Attack $ 50.00 1 Manual Valve & Hose Splat Attack $ 45.00 1 Acrylic Rod Ebay $ 26.00 1 3D SS Valve & Manifold Shapeways $ 171.09

Total $526.13

6.4 PROTOTYPE COST ANALYSIS

Some of the parts purchased did not end up being used, adding to the total cost of first prototype. The cost of the Senior Design I poster was also included in Table 3 in order to tally the total amount spent on this project, which was $674.60. Considering that the four valves required for NASA’s version of the RCS cost $1452, even with the additional costs our project still turned out at less than half the price, especially since NASA’s RCS price must be still higher when including the piping and other components. Therefore, this project can be considered a great success in terms of reducing the price of the system, as even 3D-printing in titanium rather than stainless steel should still keep the cost of our product below that of NASA’s original prototype.

Table 3 – Complete List of Parts Purchased

Quantity Part Supplier Cost 1 DRV8825 Stepper Motor Driver Pololu $ 8.95 2 Pololu Stamped Aluminum L-Bracket Pololu $ 7.90 1 NEMA 17 Stepper Motor Amazon $ 16.70 1 DC-DC 12v Step down converter Amazon $ 7.95 1 3/8-24 to 1/4" NPT SS Adapter Amazon $ 19.95 1 3/8" Tube x 1/4" NPT Ebay $ 8.25 1 1/4" Tube x 1/8" NPT Ebay $ 7.95 1 3/8" OD Steel Tube Ebay $ 12.86 1 3/8" Tube x 1/4" NPT Ebay $ 7.95 1 1/4" OD Steel Tube Ebay $ 4.98 4 3/8" Tube x 1/4" NPT 90 Bend Ebay $ 35.80 1 3/8" Tube x 1/4" NPT Ebay $ 8.25 1 1/4-18 NPT Tap Ebay $ 27.00 1 2" Clear acrylic rod Ebay $ 14.00 1 1-1/4" Delrin Rod Ebay $ 8.04 1 Parker 9-series Valve Ebay $ 50.00 1 12mm OD 6mm ID Steel Thrust Bearing McMaster-Carr $ 16.01 1 1/4 inch x 2.00 inch D-Shaft Servocity $ 1.49 1 1 inch Smooth Hub Servocity $ 5.99 1 3/8 inch Bore Parallel Tube Clamp Servocity $ 5.99 1 Surface Mount Adaptor A Servocity $ 3.99 1 3 inch ID x 1/8 inch Smooth Belt Servocity $ 0.59 1 2.5 inch ID x 1/8 inch Smooth Belt Servocity $ 0.49 1 3.5 inch ID x 1/8 inch Smooth Belt Servocity $ 0.69 1 Single Header Row Pins Servocity $ 1.49 1 Dual Screw Plate (2 pack) Servocity $ 2.99 4 4-40x1/4 inch Flat Head Screws Servocity $ 0.12 4 6-32x1/4 inch ; Flat Head Screws Servocity $ 0.15 4 4-40x5/16 inch Socket Head Screws Servocity $ 0.35 4 4-40x3/8 inch Socket Head Screws Servocity $ 0.35 1 Crossover Plate A Servocity $ 5.99 1 1/4 inch to 5mm Set Screw Shaft Coupler Servocity $ 4.99 2 Rubber Edge Trim Servocity $ 0.89 1 Shipping Servocity $ 6.99 1 48 CU Compressed Air Tank Splat Attack $ 50.00 1 Manual Valve & Hose Splat Attack $ 45.00 1 Acrylic Rod Ebay $ 26.00 1 3D SS Valve & Manifold Shapeways $ 171.09 1 Senior Poster FIU $ 60.00

Total $ 674.60

7. TESTING AND EVALUATION

7.1 OVERVIEW

Extensive ground tests will be carried out on the RCS before subjecting it to a flight test on an amateur rocket. The valve, manifold, and fittings will first be assembled and tested to ensure the required minimum force of 10 N is produced. Our calculations estimate a theoretical force of 82 N with 375 PSI at the nozzle. Using commercial hobby valves, a maximum nozzle pressure of 575 PSI is possible should more force be needed, equating to 125 N. The required longevity of the RCS system in terms of actuations is not yet established in the requirements.

Once those guidelines are available, the maximum pressure to meet the requirements can be estimated, and then tested. The governing limitation will be gas supply. The estimated life of the system is approximately 10 minutes. After this elapsed time the payload will have separated and the rest of the vehicle will burn up in the atmosphere.

The second stage of prototype testing will then commence, consisting of mounting the

prototype in an amateur rocket with an internal 6 inch (15.2 cm) diameter.

The amateur rocket, designated “Nanolaunch 1D,” will be flown by NASA once the

valve has proven successful in ground tests. The tank used will be a similar setup to the NASA

test rig shown in Figure 37.

Figure 37 – Current NASA RCS Prototype

7.2 DESIGN OF EXPERIMENTS

Several experiments were set up in order to test the following:

• The rotation of the inner valve inside the manifold

• The stepper motor’s control of the rotating valve

• The air flow through the valve

• The positive rotation of testing apparatus with activation of flow

The rotation of the inner valve within the manifold required high tolerance machining of the 3D printed parts. If the tolerances were off, the inner valve would freeze, wobble, or leak out air. The fit was continuously tested and machined, until the desired tolerances and performance were achieved.

The RCS valve was then mounted along with a stepper motor to ensure the stepper had enough torque to rotate the valve and that the shafts were aligned. This testing showed there was little tolerance in the positioning of the stepper and RCS valve. If slightly the measurements were off, the inner valve would seize in place. One way to ameliorate this issue would be to add a universal joint so that vibrations in the vehicle wouldn’t cause temporary seizure of the inner valve.

The air flow was then tested by connecting the tank directly to the RCS valve. This test showed the system was air-tight. The O-rings inside the RCS valve worked as expected. The tolerances for their fit are accurate and allow the O-rings to withstand the pressure.

The rotation of the apparatus was then tested by allowing the air flow to rotate the apparatus. This test ensured the system was free to move and that the RCS valve produced thrust.

Further development of the system will have all associated elements on the rotating structure, such as an on/off valve, control electronics, and a power supply.

7.3 TEST RESULTS AND DATA

The rotation of the RCS during testing showed that the machining was accurate and the assembly worked, as the stepper motor was able to smoothly rotate the valve between positions, which would allow it to switch which channels were open and thereby perform the desired maneuvers once mounted on a craft. These demonstrations were recorded for use in the product presentation and can unfortunately not be shown in the static medium of this report.

In order to calculate the expected pressure and air velocity at the outlet of the RCS, after all of the minor and major losses due to the piping, a simple test was conceived and executed to determine the volumetric output of the pressurized tank. Balloons were attached to the outlet of the pressurized tank, and a short burst of gas was allowed to fill the balloon. The time allowed for the burst was measured with a stopwatch, and the volume of the air captured in the balloon was then calculated by submerging the balloon in a tank and calculating the displacement of the water. Three trials were performed to minimize the experimental error due to the human factors, including reaction time and measurement errors. The volumetric flow rate of the tank was estimated to be 0.172 ft 3/s (4883.9 cm 3/s, ~ .005 m 3/s).

While not extremely precise, these measurements are enough to give a good idea of what

values to use for Section 5.2 - Engineering Calculations. A Pitot tube could not be used in this

case because of the turbulent nature of the high-pressure flow, and other measurement tools, such

as rotating vane anemometers, are more suited to smaller airflows, and therefore inappropriate

for this type of measurement.

8. DESIGN CONSIDERATIONS

8.1 ASSEMBLY

The assembly of the RCS system is a fairly simple process once all the parts have been

obtained and the valve and manifold are complete. All that is required then is to attach the tubes

and pipe fittings correctly in order to have a fully functional system.

8.2 DISASSEMBLY AND MAINTENANCE

The nature of the missions for which the Nanolaunch initiative is designated means that the rocket launches are one-way only. Once the P-POD cargo has been jettisoned from the craft, the RCS will join the rest of the rocket and the previous rocket stages in disintegrating into the atmosphere. Therefore, no disassembly or maintenance would need to be taken into consideration for the design of the RCS.

8.3 ENVIRONMENTAL IMPACT

Rockets, whether they use solid or liquid fuel, inevitably discharge ozone-depleting substances into Earth’s atmospheres, though liquid fuel may be less damaging. (14) However, the amount of greenhouse gases released by rocket launches is still almost negligible compared to that of aircraft, which actually only makes up a whopping 2-5% of the world’s CO 2 emissions.

(15) Therefore, this source of greenhouse gases can be ignored in favor of concentrating on bigger offenders, though the projected increases in rocket launches may require more attention in the future. (14) The proposed RCS design helps prevent the use of alternate RCS designs (such as Vernier rockets) that require additional fuel (and therefore pollution) in order to turn the vehicle.

The aforementioned atmospheric disintegration of the RCS will contribute to the collection of orbital debris circling the Earth’s atmosphere. (16) However, this is an unfortunate and currently unavoidable consequence of this type of mission.

8.4 RISK ASSESSMENT

Luckily, the RCS prototype construction and testing is fairly low risk. The largest liabilities are the compressed air tank and the associated dangers of using machines like lathes and mills. Anyone working with highly pressurized air must be cautious to avoid any possible explosion or uncontrolled release of air. This means ensuring that the tank does not experience any large temperature changes, and making sure not to puncture the casing.

Figure 38 – Compressed Air Tank Warning Label

Working with high-power machines like lathes and mills is to be avoided unless the user is already skilled in working with the machinery. The expertise of FIU’s Engineering

Manufacturing Center was utilized in this case, and future iterations of this RCS design will take place at a NASA center, all of which are well-equipped with expert machinists.

9. DESIGN EXPERIENCE

9.1 OVERVIEW

This project was a learning experience for all of the team members involved. There were several unanticipated delays that impacted the development of the project, including the extension of the 3D-printing production time by a week. This was a cascading issue, since all of the assembly and testing depended on the valve and manifold being complete. The team members also developed new appreciation for the safety, standards, and global considerations during the conception, assembly and testing of the RCS. These practical lessons will be invaluable experiences for our future careers as professional mechanical engineers.

9.2 STANDARDS USED IN THE PROJECT

Standards, codes, specifications, and technical regulations must be an essential part of every engineering project in order to ensure the safety and reliability of the final product. At the component level, the Nanolaunch rocket must conform to the Tripoli Rocketry Association

(TRA) and National Association of Rocketry (NAR) regulations. (1)(2)(3) At the component level, all the pipes and fittings used have to conform to the National Pipe Thread Taper (NPT) standards (4), which are defined by ANSI/ASME Standard B1.20.1. The motor driver must follow American National Standards Institute (ANSI) and National Electrical Manufacturers

Association (NEMA) standards (5), and the cap screws must conform to American Society for

Testing and Materials (ASTM) standards (6). The paint-ball tank must also follow the

Committee of Federal Register’s (CFR) requirements for portable tanks in order to allow for safe transportation (7).

9.3 IMPACT OF DESIGN IN A GLOBAL AND SOCIETAL CONTEXT

The development of an economical RCS for small rockets will have a tremendous impact on the advancement of space and earth sciences worldwide. The Nanolaunch will allow more universities and research institutions to launch experiments and observational satellites into Earth orbit. Many earth sciences and conservation efforts, including geology, water management, and forest conservation, rely on imaging and readings from orbit in order to obtain the large-scale datasets needed. Initiatives like the Nanolaunch will allow for more research of this type, which can lead to the development of efforts to improve and restore the Earth’s environment.

9.4 PROFESSIONAL AND ETHICAL RESPONSIBILITY

As engineers, it is essential to recognize our duties to the global community and ensure the public good to the best of our abilities. It is our hope that our RCS can lead to an increase in research in the aerospace and earth sciences, and that our system can open the doors to orbital research to smaller universities and institutions that have not historically had the opportunity to participate in these expense-heavy topics. We have also made sure that the system has little risk of causing injury, aside from the natural risk of working with compressed gases.

9.5 LIFE -LONG LEARNING EXPERIENCE

Designing and producing this reaction control system has been a highly interesting

experience that has cemented our love of engineering. This process has shown us the intricacies

of taking a concept, however simple it may be at its core, to functionality, and the many

challenges that arise in doing so. The team members have definitely developed respect for the

amount of effort required for such endeavors and for the real-world factors that can intrude,

including shipping delays, ordering wrong parts, and tight tolerances to meet.

At the same time, the process was invigorating, because the final product is one that can

be used by others in the real world. This is a taste of the real engineering work life, where

products need not only to be designed, but also tested, troubleshot, presented, corrected and

improved. 3D printing also turned out to be a major advantage in the construction of the part, and

it is exciting to think about which future technologies may impact the manufacturing process in

the future. To be a successful engineer, it is essential to remain abreast of new developments in

the field, especially those that will affect the design and production of your projects. This is no

chore, however, as it is a pleasure to see how technology improves and facilitates the

development of increasingly intricate, tiny and complex machinery.

10. CONCLUSION

10.1 CONCLUSION AND DISCUSSION

The proposed RCS design under development for use in NASA’s Nanolaunch initiative is very promising. It should turn out to be cheaper and more reliable than the current mechanism in testing, primarily due to its reduction of necessary input valves. Further work is needed to produce a working physical prototype for testing so that the results can be used in the next iteration of the design until the product has reached all of its objectives in terms of reliability, performance, and low cost. If successful, this project will make space more accessible for the academic and scientific community for learning and experimentation purposes.

10.2 COMMERCIALIZATION PROSPECTS OF THE PRODUCT

Due to the scalability of this rotary valve system, it can be applied to a plethora of applications. Other uses of the valve can include pharmaceutical production or any other industry where distribution of a fluid (including gases) is required. This rotary valve can be modified to include more port combinations (including multiple inputs) instead of just the four outlined in this report.

10.3 FUTURE WORK

Further development of the RCS valve system will reduce volume and mass to allow for

more versatile allocation within the Nanolaunch shroud. The current design has a wide base

required for installation of the 1/4” NPT to 3/8” tube fittings. The final version, however, could

have the tubes welded directly onto the manifold, reducing the maximum diameter of the

manifold from 1.9” to 1” (4.8 cm to 2.5 cm) and the height from 1.375” to 0.97” (3.5 cm to 2.5

cm) as shown below in Figure 39.

The 420 stainless steel 3D printing cost of the weld-ready manifold is only $35 versus

$159 for the fittings version. This also eliminates over $45 worth of fittings. Torque testing of

the valve could also lead to a smaller stepper motor such as a NEMA 8 rather than a 17.

Figure 39 – Weld-ready valve on the left

The valve is the limiting factor of RCS thrust capability. The type of on/off valve system for the gas propellant supply can also be further investigated to find a solenoid valve capable of a much larger volume (larger orifice) or a linear valve controlled by a stepper motor that can exert fine control over the gas release and hence, the vehicle response.

Figure 40 – Various types of on/off valves that could be used

11. REFERENCES

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http://www.nasa.gov/directorates/heo/home/CubeSats_initiative.html

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e/nano_overview_prt.htm

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http://www.nasa.gov/mission_pages/smallsats/elana/

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competition challenge . Retrieved from http://www.uah.edu/news/research/7317-charger-

rocket-works-designing-new-rocket-for-nasa-competition

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http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-rcs.html

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of fluid mechanics. Seventh Edition . Wiley.

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12. IMAGE CREDITS

17. Dunbar, B. (2006, July 19). Bigelow Spacecraft Carries NASA 'GeneBox' to Orbit. Retrieved

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2014, from http://newt.phys.unsw.edu.au/jw/brassacoustics.html

13. APPENDICES

13.1 APPENDIX A: DRAWINGS

13.2 APPENDIX B: PROOF OF PROJECT PRODUCTION STATUS

Figure 41 – Shapeways Receipt

13.3 APPENDIX C: ORIGINAL SWAGELOK QUOTE

13.4 APPENDIX D: STANDARDS , CODES , SPECIFICATIONS AND TECHNICAL REGULATIONS

1. "TRA High Power Safety Code". Tripoli Rocketry Association.

2. “NAR High-Power Certification Procedure". National Association of Rocketry.

3. "CAR Certification". Canadian Association of Rocketry.

4. “ASME Standards”. American Society of Mechanical Engineers.

5. “ANSI Standards”. American National Standards Institute.

6. “ASTM Standards”. American Society for Testing and Materials.

7. “CFR Standards”. Committee of Federal Register.

13.5 APPENDIX E: RAW DATA FROM VOLUMETRIC FLOW EXPERIMENT

Table 4 – Volumetric Flow Rate Experimental Data Start Trial 1 Trial 2 Trial 3 Average Time of Gas Release(s) 0.35 0.36 0.31 0.34 Water Depth (cm) 10.1 12.85 13.45 12.65 13.0 Radius of Bucket @Water Height (cm) 12.6 12.7 12.6 12.6 Total Volume (cm 3) 3543.3 5142.5 5417.3 5051.8 5203.9 Air Volume (cm 3) 0 1599.2 1874.0 1508.5 1660.5 Volumetric Flow Rate of Tank (cm 3/s) 4569.1 5205.5 4866.0 4883.9