Mechanical Engineering Capstone Project, University of Washington

8/13/2019 Mechanical Engineering Capstone Project, University of Washington

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ROCKET LAUNCH SYSTEM (RLS)ME495CAPSTONEPROJECT

DEPARTMENTOFMECHANICALENGINEERING

UNIVERSITYOFWASHINGTON

Advisor: Dr. Nathan Sniadecki, Associate Prof. of UW M.E. Dept.

Customer: Dr. Robert Winglee, Prof. and Chair of UW E.S.S. Dept.

Team Members: Mosh Berman, Garrison Burger, Trung Huynh, Walter Petersen


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EXECUTIVE SUMMARY AUGUST 21,2013Launching of high powered rockets in Black Rock Desert, Nevada over the Spring break is theannual project for the ESS 472 class. A reliable launch rail for the rockets is necessary for asuccessful launch. The launch rail used for past excursions had numerous flaws; a more reliableand functional alternative was needed.

In this project all the existing problems from the old designs were accounted for and eliminated.The largest problem was too many degrees of freedom in adjusting the rocket support rails,while the structure was over constrained in the methods in which they were secured. Thiscaused a lack in structural integrity and made preparing for each individual launch laborious andtime consuming. This projects goal was to build a better system that could be easily adjustedfor each individual launch, simple to set up after transport, and capable of attaining precisionaccuracy of the launching angle.

To accomplish easy loading of the rocket, the new design centers around being able to pivot therails about the base, enabling the rockets to be loaded in horizontally. This also allows forlaunching at precise angles other than straight up. The easy adjustment was handled by simplylowering the degrees of freedom, and having all adjustment points done with quick releasehandles rather than screws. This configuration can also be done while the assembly is in thehorizontal position, making it even easier. The whole assembly can be split up into sixsubassemblies that never need to be taken apart, and can be transported without taking upmuch space. Putting these subassemblies together after transport is simple, and takes little timeat all while being more secure and sturdy than the previous design. This security is lent by thetwo foot long stakes that secure the base of the structure. These stakes are also the mechanismfor attaining a perfectly level base.

The budget for this project as given by the customer was $500. Keeping the cost below thisfigure was challenging, especially with all the innovations planned. However, by employing costsaving measures such as recycling materials from the old design, and manufacturing someparts in house rather than buying them directly from the supplier, the overall cost of the design is

$469.13. For less than the maximum budget this design does more than just satisfy the basefunctional requirements. It goes above and beyond to make the whole process simple, elegant,and effective.

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TABLE OF CONTENTS

INTRODUCTION 6PROBLEM STATEMENT 6

Figure 1: Current launch rail system setup in the Black Rock Desert

6DESIGN OBJECTIVE 7

BACKGROUND 8HISTORY OF ROCKET LAUNCHES 8

Figure 2: Chinese soldier launching fire arrow 8Figure 3: Goddards first liquid rocket and launch stand 9Figure 4: German V-2 and Meillerwagen Transport Vehicle 9Figure 5: Tower Launcher 10

PREVIOUS DESIGN 10Extruded aluminum frame 10

Figure 6: Extruded Aluminum Frame 11Plywood Platform 11

Figure 7: Platform Diagram 11Launch Rails 11

Figure 8: Launch rail design. showing degrees of freedom, screws, L-bracket, and top-down view of rocket in the system. 12

DESIGN PROBLEMS 12Setting Up for a Rocket 12Loose rails 12Loading Rockets 13Degrees of Freedom and Constraints 13Interference 13Other Issues 13

ECONOMICS 13SUSTAINABILITY 14ENVIRONMENTAL ISSUES 14ETHICAL CONCERNS 14SOCIAL IMPACT 15

DESIGN 16PRELIMINARY CONCEPTS 16

Functional Requirements 16Primary 16

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Secondary 16Other Considerations 16

INITIAL DESIGN 17General Construction 17Backbone 17

Figure 9: Structural Backbone Diagram 17Backside Rails 18

Figure 10: Backside Rails Diagram 18Base 18

Figure 11: Base Structure Diagram 19Supports 19

Figure 12: RLS diagram showing supports and movement 20Details 20

Figure 13: Panel Holders (Left) and Tube Holders (Right) 21Figure 14: Rod Hook (Left) and End Tube Holder (Right) 21Figure 15: Initial design, top and isometric views 21

FINALIZEDDESIGN 22Figure 16: New backbone and side extensions (left hand version) 22Figure 17: New overlapping joints without panel holders. 23Figure 18: Dual Rod Holder (left), Nylon Sliders (right) 23Figure 19: Leveling Mechanism 24Figure 20: Sleeve bearing and new geometry 24Figure 21: Final Design 25

MATERIALCHOICES 25FEASIBILITY 26

DESIGNANALYSIS 26Hinge Support 26

Figure 22: Von Mises stress in the hinge support under structural weight 26Figure 23: End-Feed Fastener for T-Slotted Framing 26Table 1: Fastener Specifications 27Figure 24: Problem Geometry 27

Rod Sizing 28Total Mass 28Launch Forces 28Temperature and Fatigue 28

COST ANALYSIS 28SOIL ANALYSIS 29

Table 2: Typical particle size and distribution of Black Rock Playa [10] 30IMPLEMENTATION 31

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MANUFACTURING METHOD 31ASSEMBLY METHOD 31

Figure 25: Base Assembly Explode 32Figure 26: Left-hand Backbone Assembly Explode 32Figure 27: Backside Rails Assembly Explode 33Figure 28: Support Assembly Explode 33

TRANSPORTATION METHOD 34USER INSTRUCTIONS 34

Launch Site Assembly 34Figure 29: Launch and Loading Positions 35

Rocket Loading 35Care and Cleaning 35

SAFETY PRECAUTIONS 36FUTURE WORK 36

REPORT SUMMARY 37REFERENCES 39APPENDICES 41

APPENDIX A:MATERIAL PROPERTIES 41Aluminum 6061-T6 [16] 414140 Cold Drawn Steel [17] 41

APPENDIX B:ROD SIZING 41APPENDIX C:LAUNCH SPEED 43APPENDIX D:COST 44

Parts 44Stock 45

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INTRODUCTIONPROBLEM STATEMENTEach winter the ESS 472 class at the University of Washington makes their way to Black RockDesert, Nevada with high powered rockets in tow. These rockets measure two inches in

diameter for certification flights, and three to four inches in diameter for the twelve foot or longerM and N class rockets. Occasionally even larger rockets may be launched such as the six inchdiameter, fifteen foot tall rocket built for a NASA Innovative Advanced Concepts (NIAC) proposaldesigned for high speed impact. Such large rockets produce an incredible amount of thrust inorder to take flight. These forces must be controlled and directed during a launch in order toensure the rocket flies in the intended direction without failure, and does not lead to injury orsome other disaster.

For the Winter class of 2013, a new launch rail system was designed and built to accommodatethe rockets that would be launched that quarter (Figure 1). In order to maximize flexibility, asimple frame was designed from extruded aluminum rails. However, this flexibility caused thesystem to be extremely difficult to use and was lacking in functionality. After using the system for

a week of launches many failures and shortcomings were observed, and it became clear that animproved design was needed.

Figure 1: Current launch rail system setup in the Black Rock Desert

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DESIGN OBJECTIVEThe design of a new rocket launching system must improve on the failures of the previoussystem while adhering to several core necessities.

With the possibility for so many different combinations of diameter, height, weight, fin design,and thrust output, a system designed to control and direct these rockets during a launch mustbe both versatile and durable. The system must withstand the forces of many launches insuccession with little to no need for maintenance between launches. This system must have theability to accommodate rockets with diameters from two inches to six inches with minimaladjustment for switching between different diameters. The system must also be able toaccommodate rockets with either three or four fins with the need for little to no adjustment toswitch between the two.

An ideal launch system would be easy to assemble, and not terribly heavy. From time to time,rockets will be designed to have odd fin arrangements such a 6 motor cluster, or a glider rocket.Thus, the launch system would ideally be able to accommodate these rockets as well, thoughthe main requirement is to handle standard rockets. The ideal angle of launch may changedepending on the direction of the wind and the desired touchdown location. Thus, the ideal

system would be capable of launching from any arbitrary angle. The system should also bedesigned so that the rocket does not sit directly on a flat surface, as this would block the nozzleof the rocket.

During launch the rockets will produce an immense amount of thrust to propel the rocketupwards. The system should be designed such that the force on the frame is minimal, and forcefrom the exhaust is not directed straight into the frame.

Rocket Launch System (RLS) will be a new system to hold a rocket vertically and control itsdirection during launch. All problems of the previous system will be addressed and RLS will be amuch more reliable and durable solution for years to come.

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BACKGROUNDHISTORY OF ROCKET LAUNCHESThe first reported use of a true rocket was in 1232 [1]. The rocket was used by the Chinese torepel the Mongols during the battle of Kai-Keng. These were simple rockets made from a tube

capped at one end, containing gunpowder and attached to a stick to keep them heading in onedirection. These rockets were fired from very primitive launch rails which consisted of two Xconfigurations made of two sticks tied together and driven into the ground. The rocket wasmounted on these Xs and fired (Figure 2). This marked the beginning of rockets and launchsystems.

Figure 2: Chinese soldier launching fire arrow

The Mongols adopted this technology and eventually brought it to Europe [1]. During the 13thand 15th centuries, there were many experiments conducted with rockets. One of theseexperiments was carried out by a monk living in England who greatly increased the range ofrockets when he invented a new improved form of gunpowder. These new rockets required anew launch system. This led Jean Froissart of Italy to the discovery that greater accuracy couldbe achieved by firing the rockets from a tube [1].

In the 17th century, Isaac Newton (1642-1727) began to lay the groundwork for modern dayrockets. He formulated the three laws of motion which helped scientists around the worldunderstand the physics of motion. These three laws of motion explained how rockets work andallowed for major developments in rocket science to begin to take place [1].

With new knowledge of how rockets work, rockets began to increase in size and weight. In themid 1700s in Germany and Russia, rockets with masses in excess of 45 kilograms weresuccessfully launched [1]. These rockets produced so much thrust that they wound up blastingsizable holes in the ground prior to lift off. This is when experimenters began to recognize theneed for blast plates during launches.

In the Late 1700s and early 1800s, war revived the rocket as a weapon [1]. This meant the

rocket as well as its launch system underwent some further improvements. Theseimprovements increased the rockets range capabilities and gave greater accuracy.

During the 19th century, Sir William Congreve developed a launch system specifically designedto be mounted on ships. Originally the rockets launched from these ship mounted systems weremeant to set fire to enemy shorelines [2]. The rockets fired from these launch systems werelater termed Congreve rockets after their designer and were the most commonly used rockets inbattle until William Hale invented the Hale rocket in 1844 [3]. Hale also invented the Hale rocketlauncher which was a 6 foot iron tube with a bipod for setting the elevation and a movable

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restrictor plate for adjusting the range [3]. Hale rockets were more accurate than Congreverockets and had a slightly greater range as well [2].

In 1898, the idea of space exploration with rockets was introduced by a Russian school teachernamed Konstantin Tsiolkovsky (1857-1935) [1]. His suggestion for the use of liquid propellant toachieve greater range has led Tsiolkovsky to be called the father of astronautics [1].

On March 16, 1926, Robert Goddard achieved the first successful liquid propellant rocketlaunch, earning him the title of father of modern rocketry according to NASA. This rocket wasfired from a 7 foot tall semi-pyramidal frame which held the 10 foot rocket upright (Figure 3).Two fuel lines extended up the rocket to the motor from the bottom of the rocket; one line forgasoline and another for liquid oxygen. The gasoline tank and oxygen cylinder were underneaththe rocket on the ground protected by a cone shaped exhaust shield. [4].

Figure 3: Goddards first liquid rocket and launch stand

Following the realization that liquid fuels held far more range potential than solid fuels, was thedevelopment of the first long range rocket, the Vergeltungswaffe 2. The V-2 rocket was used byGermany against London during World War II (1939-1945). These rockets were originallylaunched from underground bunkers or fixed pads, but were later capable of being launchedfrom practically anywhere from a mobile system called a Meillerwagen transporter vehicle [5].The Meillerwagen was a six wheeled vehicle which had a rail system designed for raising andlowering of the V-2 rockets that sat on top of it (Figure 4).

Figure 4: German V-2 and Meillerwagen Transport Vehicle

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On July 16, 1969, the Apollo 11 landed the first humans on the moon. The Saturn V rocket waslaunched from Launch Complex 39 (LC-39) of the Kennedy Space Center [6]. This launchcomplex consists of a giant launch pad on which the shuttle is placed. The space shuttle isconnected to a massive launch tower. The tower contains a two-piece tower system; the FixedService Structure and the Rotating Service Structure [6]. Access to the space shuttle wasavailable via retractable mechanical swing arm systems that extended from the launch tower to

the Space Shuttle [6]. The Kennedy Space Center has 3 of these such structures. STS-135launched on July 8 2011 and marked the last Space Shuttle launch. However, future rocketlaunch technology such as the SLS [7] will still utilize a massivelaunch pad and tower system.

Within the model rocket community there are two main types oflaunch systems. One is a single rail system. In this type, a singleslotted extrusion is held upright by a base. Rail buttons areattached to the rocket that slide down the slots. This type of systemworks fine for smaller rockets, but the size and power of the rocketsused by the ESS 472 class would not work with such simple rails.The buttons on the side of the rocket also create aerodynamic drag

and turbulence, slowing the rockets down. The second type of railgenerally employed by the hobby community is a tower system. Insuch a system the rocket does not directly attach to the rails but isheld on multiple sides by long rails. This can hold even largerockets upright without adding any drag to the rocket. Most towersystems are custom built, only a few can be found for sale. Thesimplest of these only work for smaller diameters (one is ownedand used by the ESS 472 class already), and larger systems areprohibitively expensive. One system, called the Tower Launcher(Figure 5) [8],seemed to meet the needs of the class, but no pricewas available. It was estimated that the price would most likely beabove budget, and building it would require welding experience,

which none of the team members have. The features of this designwere considered and some were incorporated into the RLS.

Figure 5: Tower LauncherPREVIOUS DESIGNThe previous design of the launch rail system had many shortcomings. The design andproblems of the old system are detailed below.

EXTRUDED ALUMINUM FRAME

The frame was made of aluminum T-slotted extrusions. The frame consisted of four verticalextrusions in a square. Each side had three cross-beams, one each at the top, middle andbottom of the frame (See Figure 6). The vertical extrusions extended a bit below the bottomcross-beam and sat in holes in the plywood base. The structure was stabilized by ropesattached to each of the four corners at the top of the frame.

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Figure 6: Extruded Aluminum Frame

PLYWOOD PLATFORM

The platform base consisted of a frame made from 2x4s with a plywood sheet over the top. Inthe middle of the platform was a steel blast plate, held down with screws overlapping the edgesof the plate. (See Figure 7)

Steel PlateEdge Screws

Wood + Plywood Platform

Figure 7: Platform Diagram

LAUNCH RAILSThere were five launch rails also made from extruded aluminum. Each launch rail connected tothree horizontal supports that extended to the outer frame. The supports were connected to theframe by a single L bracket each. One screw loosened the supports from the L bracket to slidein and out, and another loosened the L bracket from the frame to rotate the rail and allow thesupports to slide side-to-side. Each rail had three degrees of freedom (blue arrows) and sixscrews (red arrows) constraining it. The rails were also extended above the frame by attachingtwo extrusions end-to-end. Two of the launch rails also had brackets to hold the end of the

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rocket off of the platform. Depending on how many rails were needed for a rocket, some couldbe put out of the way to the side. (See Figure 8)

Figure 8: Launch rail design. showing degrees of freedom, screws, L-bracket, and top-downview of rocket in the system.

DESIGN PROBLEMSWhile the launch rail did function in the most basic essence of the word, over the course of fourdays of using the system many issues with the design came to light.

SETTING UP FOR A ROCKET

Since both 3 and 4 fin rockets were being launched, the system had to be completelyreconfigured each time a rocket was loaded. Since each rail has 6 screws, setting up for a newrocket required adjusting 18-24 screws. This alone consumed a large amount of time.

LOOSE RAILS

The design of this rail system meant that the rails were located far away from the frame. Thisallowed a large moment to be applied to the screws holding the rails in place with just a smallhorizontal force on the rails. This caused problems when both launching rockets and whenloading them.

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LOADING ROCKETS

Since the launch rail - and many of the rockets - were so tall it was difficult to load them into thelaunch rail. For many rockets, sliding them in at an angle from the side proved very difficult. Itwas found easier to tilt the whole thing over. This required several people to lower the rail, andthe posts engaged with just holes in the plywood it was even more challenging. Additionally, the

tie down ropes had to be removed and the stakes had to be re-hammered into the ground eachtime.

To attempt to make the process easier, a couple of the rails were adjusted beforehand so thatthe rocket could simply slide down them when it was tilted downwards. However this did notwork well as the rails would simply shift out of place as soon as the weight of the rocket was puton them (the moment arm issue again). This required more readjustment when the rail wasvertical again.

DEGREES OF FREEDOM AND CONSTRAINTS

Each rail in this design had 3 degrees of freedom. They could rotate, slide side to side, and slidein and out. Each rail was constrained to these degrees of freedom by 6 screws (3 sets of 2).However each set of two screws on each support beam already constrained the rail to these 3degrees of freedom, meaning that each rail was two times over constrained. This is whatcaused the most problems when adjusting the system. It meant that there were too manyscrews and it was difficult to get each rail into place and tightened down.

INTERFERENCE

Another issue that compounded the problem was interference of various parts. The rails satagainst the platform, such that when one was attempting to slide one into place, it would catchon the blast plate and things would have to be forced around to shove it into place. Additionally,the two brackets that held the rockets off the ground would oftentimes interfere with each other,causing the rails to not be able to be placed in an optimal position along the rocket body.

OTHER ISSUES

There were other problems as well:

Support rails were sometimes too short, limiting the positions in which the rails could beplaced.

The constant loosening and tightening of the rails, and the fact that they needed to be verytight to have any sort of stability meant that screws started to strip.

The extensions of the rails were not attached well and not very straight.

There were several times when the L-brackets that held the support beams to the railsbent, ruining the rail.

The rails would not stay in place during a launch, and screws would loosen.

All in all, the design of the previous launch rail system, while very flexible, was also prone to

many problems. The goal is to fix these problems and design a system that is robust and easyto use.

ECONOMICSThe cost of the previous launch system was approximately $217.30 (Table A.1), not includingshipping costs. A budget of about $500 has been approved by the customer to develop andbuild the RLS. The selection of parts used in the design will be chosen with this budget in mind.The components used in extruded aluminum systems are typically expensive. Where possible,

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parts will be recycled from the last design. Additionally, if a part can be machined using availableresources, making the part rather than buying it will be considered.

SUSTAINABILITYThe new system should be expected to have at the very least a ten year lifespan. The parts andmaterials should be selected such that they can withstand degradation caused by the launches,as well as the harsh desert environment. Assembly, use, and transport of the system every yearshould not severely damage the parts. The parts that are most likely to undergo wear in anysystem are the fasteners, especially those that are repeatedly used. Moving parts should bedesigned with this in mind to maximize the life of the fasteners. However, eventual fastenerreplacement is affordable, and an acceptable prospect. All frame pieces on the other handshould not be expected to be replaced, although in the case of accident the option should beavailable.

ENVIRONMENTAL ISSUESWith the RLS design there should be extremely low impact to the environment. Due to theobjective of the design there is no need for any energy input to the system other than human

force in setup. The only possible environmental concern during operation is the exhaust of therocket causing a reaction with the materials used in the RLS. The parts that will encounter themost of the exhaust will be the baseplate and the rocket supports, which are solid metal anddesigned for the encounter. Any possible reaction is expected to be absolutely negligible as therocket exerts exhaust onto the structure for a period of no more than a few seconds. It shouldalso be noted that the while the aluminum parts may have melting temperatures lower than therocket exhaust, the transient heat will dissipate quickly as the past design showed.

Other environmental issues come from the making of the materials and product retirement.While the manufacturing of the raw materials cannot be controlled by the scope of this project,plans can be made for recycling of product parts. When the RLS has reached the end of itslifespan its parts will be recycled to the various student shops around campus, where they canbe put to use on other projects. On the subject of replacing parts should they fail, the failed partscan be recycled in the same manner.

ETHICAL CONCERNSThe ethical concern for this project deserving the most attention is that of simply delivering asuccessful product. The students of the ESS 472 class spend the entire quarter building thesemagnificent rockets; to have all their hard work thrown away due to a launch accident caused bythe RLS is completely unacceptable. This must be accounted for both in design, and in userinstruction. A design that simply does not deliver what is promised goes entirely against thecode of ethics engineers must hold themselves to. Even the finest design can utterly fail by usererror, with poor instructions to blame. The many degrees of freedom on the RLS and theunfamiliar design introduce these potential failures, but can be easily accounted for by proper

instruction. Users need to practice before operating the system for the actual launch.Besides the potential for ruining all the hard work put into the rockets, the nature of the task theRLS sets out to accomplish presents several possibilities for accidental cause of harm to theuser. These sources of potential harm must be well document such that they may be avoided.Carrying the RLS with negligence could cause such an accident. Sharp surfaces should have awarning label adhered to them, proper lifting instructions should be outlined, etc.

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SOCIAL IMPACTWithout a proper rocket launching system, the entire purpose of the ESS 472 class is defeated,that purpose being to launch the high powered rockets that they design. Taken from the coursedescription, Students launch science payloads to high altitude using high power amateurrockets, providing design, fabrication, test, integration, and management experience; covers

science motivation, engineering aspects, and delivery systems. This is an important hands onexperience for students in this field, and by providing them with helpful, easy to use solution forlaunching their rockets is extremely useful for their success.

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DESIGNPRELIMINARY CONCEPTSAfter examining the flaws of the previous launch rail system and researching launch railmethods, the imperative functional requirements for the project were determined. These are

listed below.

FUNCTIONAL REQUIREMENTS

Primary

Withstand forces of launch

Hold rocket in alignment until aerodynamic forces take over

Accommodate 2 - 6 diameter rockets

Accommodate rockets with 3 or 4 fins

Ease of loading the rocketSecondary

Easy to assemble

Able to level base

Accommodate rockets with odd fin arrangements (6 motor cluster, glider rocket) Launch at any arbitrary angle

Other Considerations

Windy conditions

Rockets cannot sit directly on flat surface

Fins should not catch on structure

Needs to be transported in a cargo van

To address the above requirements, several core design parameters were determined. To holda cylindrically shaped rocket in place, there must be at minimum three points of contact on therocket body. These points must be distributed somewhat evenly so that there is no direction in

which the rocket could simply fall out. These points of contact should be straight and continuousalong a significant portion of the rockets body so that it is held upright during launch. The pointsof contact must also be adjustable to the various sizes and configurations of rockets to belaunched. From previous experience, the easiest way to load the rocket was from a horizontalposition, so the rail should contain a method of easily tilting over for loading.

Based on these parameters, two primary paths were considered. One would improve on thecurrent design and the other would start a new design from scratch. The same large framewould be used with adjustable rails. The entire frame would sit on a level-able base and tilt forloading. The attachment of the rails would be reconsidered to address the previous issues.However, in fixing the old design there would be many significant challenges. Addressing all ofthe issues while keeping the same concept would be too difficult, if not impossible. It wasdetermined that a new design from scratch would be a more efficient means to a successfullaunch rail system.

This new design began with two right-triangle-shaped backbones, spaced apart such that therocket could slide along their edges, giving two points of contact for the rocket, with a spacebetween them for a fin. The width of the gap would be adjustable and would attach to a lowerhinge for rotating the system to horizontal. A third, and possibly fourth point of contact would belocated on the opposite side of the rocket and be adjustable radially from the rocket, toaccommodate different sizes. A base would attach to the ground that can be leveled to keep thesystem vertical.

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INITIAL DESIGN

GENERAL CONSTRUCTION

Using the above description, an initial design began to form. The launch rail system isconstructed of aluminum extrusions for vertical elements. Sheet metal holds the extrusionstogether with the use of panel holders. Rods are used to both hold the structure together and forelements that need to slide and/or rotate.

BACKBONE

The design centers around the triangle backbones, which consist of vertical aluminumextrusions making the corners of the triangles, with sheet metal holding them together. Thesealuminum extrusions create two contact lines along the length of the rail, which the rest of thedesign builds off of. To adjust the spacing of the backbone, two rods are attached horizontally.The bottom rod also provides the rotational axis for moving the system into loading position, andthe top rod provides an attachment for the supports.

Top SideFigure 9: Structural Backbone Diagram

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BACKSIDE RAILS

Two additional rails are located on the back side of the rocket. Bent sheet metal arms wraparound the rocket to provide attachments for the rails. Rods allow the rails to slide radially fromthe rocket, at a precise angle that provides clearance for three or four fin rockets of varyingdiameters. An issue that was discussed, but ultimately never solved before the final design, was

a method of securing the two arms together on the back side. It was not clear how flimsy theywould be and if an easy method of holding them steady was even possible.

Top SideFigure 10: Backside Rails Diagram

BASE

The base is constructed from aluminum extrusions in a square pattern. The square is heldtogether by triangular sheet metal braces in the corners. These braces each have a hole for atwo foot steel stake to hold the base to the ground. The base would be leveled by finding a

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relatively flat section of ground and shimming where necessary. The base would have twotriangular supports for holding the rod on which the backbone structure rotates upon.

Top SideFigure 11: Base Structure Diagram

SUPPORTS

To keep the structure upright, two more aluminum extrusions are attached at an angle to the toprod as well as an additional rod held to the ground several feet from the main structure. Theposition of this rod determines the angle of launch and can be positioned such that the rocketcan be launched at any arbitrary angle. The support also provides structural stability by creatinga wider footprint. If additional stability is required, tie lines can be connected to the top of thestructure, as before. However, should severe weather arise, the structure can be lowered

horizontally since rockets should not be launched in high winds.

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Figure 12: RLS diagram showing supports and movement

DETAILS

Since the design featured aluminum extrusions, McMaster-Carrs section of T-Slotted Framingparts was consulted for ideas of how to hold the frame together. Panel holders seemed to be thego-to solution for attaching sheet-like parts to extrusions (Figure 13). To attach rods, thestandard tube holders were used in the design (Figure 13). It was seen that some tube holderscould come with adjustable handles, which worked perfectly for the RLS. In some cases, it wasdetermined that alternate tube holders would be needed. At the base of the support a sort ofhook over the rod was required, so keeping the overall dimensions the same, a new part wasdesigned to meet the required functionality (Figure 14). Similarly, where the back rods attach to

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the back rails, a tube holder was needed that could hold a rod perpendicular to the rail. In thiscase instead of clamping the holder to the rod, holes are put through the rod and holder forfasteners (Figure 14). By using the above parts and standard T-Slot fasteners, the RLS can beassembled. The full initial design is shown in Figure 15.

Figure 13: Panel Holders (Left) and Tube Holders (Right)

Figure 14: Rod Hook (Left) and End Tube Holder (Right)

Figure 15: Initial design, top and isometric views

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FINALIZEDDESIGNAfter numerous design reviews, and receiving a multitude of suggestions and comments from avariety of audiences, necessary changes to the design began to make themselves clear. Themost noticeable change was to the frame holding the back rails. The bent pieces of sheet metalwere deemed both flimsy, and overly complicated. These were replaced with a square frame

made up of more one inch aluminum extrusions of various lengths, and aluminum rod (Figure16). The benefits of this change were widespread. There were leftover pieces of extrudedaluminum, which meant they could be recycled for this purpose as well. In fact the final designcan use recycled pieces of extruded aluminum for all but two of the eight foot long sections. Thesquare profile of the frame greatly simplified the design, while enabling the rod which connectsthe frame to be held in place by the same rod holders used elsewhere in the design.

Figure 16: New backbone and side extensions (left hand version)

This in turn caused two major changes. The triangle profile of the structural backbone needed tobe widened in order for the square profile to clear the fins. In doing so their translational spacewas increased, enabling them to engage the rocket sides farther away from the midplane. Thiswill keep the rocket from falling out of the rails in the direction perpendicular to the structuralbackbone angle of attack. The widening of the triangular profile also, along with some designreconsideration, allowed us to remove the need for the double extrusions, and replace themwith singles at half the cost. The panel holders attaching the sheet metal pieces making up thestructural backbone were removed and instead the sheet metal pieces would be attacheddirectly to the extruded aluminum. This completely cut out that part, saving substantial cost andmanufacturing time. The profiles were changed to overlap in order to reduce extraneous mate

features and their fasteners (Figure 17). With this new method of attachment and geometry, itwas decided that the sheet metal thickness could be changed from one fourth inch thick to oneeighth inch thick. This would again reduce the cost, and it would be easier to work with inbending.

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Figure 17: New overlapping joints without panel holders.

The second major change was to the method of securing the extendable rods holding the

extruded aluminum guide rails, as well as their angle of attack. It was realized that instead of aprecise angle, the rails would work equally well as parallel rails with a small separation. The twoclose rails still allow for a rocket with 4 fins but practically function as a single point of contact.Therefore the two backbone rails must now be significantly spaced so that there are 3 solidpoints of contact for the rocket.

The singular rod holders were replace by a custom double holder that was designed based offof the same concept employed by the single (Figure 18). It allows the extension rods to beproperly located should any alignment issues occur. By adding nylon lengths to the inside ofextrusions (Figure 18), it also ensures that the rocket cannot spin and catch one of the fins onany part of the structure by constraining the rotational axis of the rocket. These improvements tothe extension rails in conjunction with the change to the structural backbone of the designflipped the rockets orientation 180 degrees for some fin arrangements. It also reduced the costof the system and created a sturdier structure for the back rails to attach to.

Figure 18: Dual Rod Holder (left), Nylon Sliders (right)

The square base of the structure went under significant improvement. The ability to keep thebase level and in place via shims and stakes may be difficult due to the soft first couple inchesof soil. The redesign involved turning the stakes into partially threaded rods complete with staketip. These would be held against the sheet metal triangular plates facing flat to the ground with

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two nuts on either side (Figure 19). These can be adjusted in each of the four corners, to attaina perfectly level surface for the rest of the structure to build off of. However, the cost of thesethreaded stakes is significantly higher than the cost of simple stakes. Therefore, a budget optionusing the simple stakes will be provided to the customer.

Figure 19:Leveling Mechanism

The triangular pieces of sheet metal holding the aluminum rod on which the entire structurepivots were analyzed both for both direct load, and fatigue. The held up to load tests withimpressive safety factors, but a fatigue induced failure needed to be addressed. This wassolved by adding sleeve bearings (Figure 20)to the joint in which the rod is slid through. Theirgeometry was also changed to clear other change induced interferences.

Figure 20: Sleeve bearing and new geometry

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Finally, a summary of small changes can be noticed. The quick release was removed from halfof the rod holders, as they were superfluous, which was a helpful cost reduction. Theplacements of these rod holders were also changed in various locations to accommodate otherpart changes. A support bracket was added to the support rail assembly in order to keep italigned and protect against shear forces. The finalized design can be seen below in Figure 21.

Figure 21: Final Design

MATERIALCHOICESThe material making up the largest percentage of this projects parts as may already beapparent, is aluminum. Specifically, Multipurpose Alloy 6061 Aluminum, the specifications of

which are shown in Appendix A. The cheapest and most widespread T-slot extrusions aremade using aluminum, of which several pieces of various lengths from the previous rail systemcould be recycled for this construction. Aluminum was also an obvious choice for the sheetmetal pieces and the rods, as steel would be far more expensive, unnecessarily strong, and beheavier. The rod holder blocks will be made of aluminum as well, along with the extended railholders.

The material for the threaded stakes was chosen to be steel. The stakes must be able towithstand being driven into the ground approximately eighteen inches, and then wrenched outwith a pipe wrench many times throughout their lifespan. This requires a great deal of strength,resistance to elements, and durability, characteristics which could not be met by aluminum. Thetype of steel decided on was Multipurpose 4140 Alloy Cold Drawn Steel, detailed in AppendixA.

The rest of the materials are listed below.

The bearings for the base are made of brass SAE 863.

The nylon fin bracers are wear resistant nylon 6/6

End-Feed Fasteners for Aluminum T-Slotted framing and the hex nuts are made ofstandard zinc plated steel.

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FEASIBILITYDESIGN ANALYSISIn order to be sure the design performs as expected, several areas of analysis were applied tovarious parts.

HINGE SUPPORT

First and foremost was a strength test on the vertical triangular brackets on the base whichsupports the weight of the entire structure at the pivot point. The heaviest rocket can beexpected to weigh around sixty pounds, and the combined weight of the structure totals toaround fifty pounds. Based on this total of 110 pounds, a stress test was performed usingSolidworks SimulationXpress. Even at the highest stress location, the stress was close to onlyhalf of the yield strength of the material, giving a factor of safety close to 4.5. A plot of the vonMises stress is shown below in Figure 22.

Figure 22: Von Mises stress in the hinge support under structural weight

However, this assumes that the screw holes of this piece are fixed. To be absolutely sure thestructure can support itself, the forces induced on the screws themselves needed to beanalyzed for possible shear forces. Figure 23shows the type of screw being used for thisoperation. The triangular plate is 1/4 thick, which leaves 5/32 of threaded length past the endof the plate nut. The screw is made of standard zinc plated steel (AISI 1018). Table 1shows thefastener specifications for this problem and Figure 24shows the problem geometry.

Figure 23: End-Feed Fastener for T-Slotted Framing

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Tensile Strength

Yield Strength

Proof Strength

Cross Sectional Area

64 ksi

54 ksi

55 ksi

0.049 in2

Table 1: Fastener Specifications

Figure 24: Problem Geometry

Although there will be preload due to the torquing of the screws, the worst case situation withoutany preload was analyzed. The shear and moment can be calculated about the centroid of thetwo screws, which is found by symmetry, along with the distance to the centroid from each bolt

V = 55 lbs M =135 in-lbs r =1.25 inThe primary shear per bolt, where n is the number of bolts is:

F' =V

n= 22.5 lbs

By eq. 8-57 [21], the secondary shear is:

F'' =Mr

nr2 =

M

2r= 43.2 lbs

In this case both shear forces point along the same line; for the bolt on the right they areadditive, whereas those on the left bolt are in opposite directions. This means the maximumshear force is acting on the right bolt and is:

F = 65.7 lbs

! =

F

A=1.34 ksi

As this clearly shows, the maximum stress is far below the shear strength of the bolt.

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ROD SIZING

A rod size of 1 inch was selected since that was the size used for the standard tube holders. Toprove that this size was acceptable, a stress analysis was performed on the rod (Appendix B).The analysis used the von Mises method for plane stress. Using 1 inch as a starting point, thecalculations showed that a rod of 5/8 would meet the stress criteria. Therefore, the 1 inch rods

are completely valid and hold up to a safety factor of 9.4.TOTAL MASS

The total maximum weight of 110 lbs also needs to be taken into account for moving thelauncher from the loading horizontal position to the firing vertical position. It should not beunreasonable that two people alone should be able to lift the structure up from horizontal tovertical, and similarly lower it. The pivot point takes care of some of the weight (more and moreas the structure is raised). When the structure is horizontal, approximately half the weightshould be on the pivot, and half on the top of the frame. This means that one person couldreasonably lift the structure, and two could do it with ease. On average there are around fortypeople on the trip, most of them being students, people more than capable of lifting thestructure. While it is most likely that at least four people will aid in this process to keep

everything steady, it can be reasonably done with only two people.

LAUNCH FORCES

The forces of the rocket during launch also needed to taken account for. For a normal launch,no large forces should be put on the structure by the rocket body. Such a force would mean asevere loss of power behind the rocket. The rails should simply guide the rocket in the correctdirection. However, the exhaust of the rocket may have some significant force. This wasanalyzed at the point directly bearing that load, the rocket stop triangle pieces. The maximumthrust force of any rocket is around 10,000 N, created downward at the beginning of the launch.Realistically, much of this force will be either dissipated in the air, or flow around the structure.Just as a broad assumption, if half of this force being distributed over the two stops, with therest flowing around, there is a 2,500 N force per element. This is an extremely worst-case

estimate of force, and yet the support piece holds up to nearly a factor of safety of 2 at the moststressed portion. This force is also only applied for a tiny amount of time. For even the weakestrockets, in 1/10 of a second they are already .25 m above the stop and moving at 5 m/s(Appendix C). Additionally, since the same rocket stops worked in the previous system, it isfairly certain that they will work in the RLS as well.

TEMPERATURE AND FATIGUE

All parts were also considered in terms of a temperature and fatigue analysis, but no hardcalculations were made. The highest and lowest ever recorded temperature for the desert areboth vastly exceeded by the materials operating temperature ranges. As for fatigue, there areno parts that spin continuously, and only parts that need to be able to rotate in place whenneeded. All of these are accounted for by either bearings, or quick release clamping

mechanisms.

COST ANALYSISThe cost of the RLS was calculated using the prices of the raw stock and the purchasedcomponents. A detailed line-item list can be found in Appendix D. The total cost of the RLS is$469.13. This gives enough overhead for unforeseen costs such as additional fasteners andsmall components. Several measures have been taken to keep the cost low. First, 10 of the 12eight foot long rails have been recycled from the last design. If these were to be bought new

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they would cost $26.38 each for a total of $263.80. In addition a key component of our design,the rod holders, are being machined by the team rather than purchased. By doing this the costfor those parts is reduced from $545.60 to a mere $137.41. Throughout the design process thecost was minimized in several ways. One such way was in changing from the original plan ofusing panel holders (expensive or difficult to make), to directly attaching the sheet metal to therails. Another way the cost could be even cheaper is through the use of budget stakes. These

stakes would just be normal stakes and require no machining. While they are cheaper, theplatform will have to be shimmed to make it level, which may not be preferable to the customer.The budget option would save $59.71 making the total cost $409.42 which is well under budget.

The cost of manufacturing parts has not been analyzed, merely the stock material to be used.Since this is a single production product, the cost of the labor put in by the team is notassessed. Were this to be a continuing product, these costs would need to be reanalyzed.Doing this would certainly raise the price of the system, and the design would need to changedrastically to meet the same budget. Due to the nature of this project, free labor and recycledparts keeps the cost of the system much lower.

SOIL ANALYSIS

The Black Rock Desert in northwestern Nevada is one of the largest flattest surfaces on Earth[10]. The Black Rock Desert represents the dried up bed of the former Lake Lahontan whichoccupied the area approximately 15,000 years ago [11]. Being one of the flattest knownlandforms, the Black Rock Playa encounters numerous forces and is subjected to very harshtreatment by the elements. Despite the fact that the Black Rock Desert is just that, a desert, oneof the most important processes that the playa is affected by is flooding. Flooding of the playaoccurs every few years, and sometimes even more frequently. This flooding plays a key role inkeeping the playa surface flat and hard.

During the summer following a year of heavy rain, the playa surface is hard and relativelydurable thanks to the water which is slowly absorbed into the surface. Once this waterevaporates, it leaves behind salt, sand, and mud along the bottom of the playa which dries and

hardens. This hardness and durability is evidenced by the lack of vehicle track marks. Fewtracks visible on the playa surface means that the surface is being only slightly affected byvehicle traffic, suggesting the surface is strong. However, over time between storms and withincreased vehicle traffic, the playa surface becomes decreasingly compact and tends to formlooser layers of dust and ripples. These looser layers are also more susceptible to wind drivenerosion which in turn loosens the playa surface even more and worsening the surface quality ina snowballing effect.

According to study published by the Desert Research Institute (DRI), the Black Rock Playa iscomposed primarily of fine-grained sediments dominated by silt- and clay-sized particles.Typical particle size and distribution in soil samples analyzed by the DRI are summarized inTable 2. The dominant constituent in all samples was clay, accounting for 51.5% to 92.4 wt %.

Fine sand accounted for 0.8 to 10 wt % and soluble salts such as sodium chloride account foronly 0.64 to 1.94 wt %. The most common minerals found in the playa sediment are quartz,calcite, feldspar, and various types of clay, with far lower concentrations of vermiculite, illite, andkaolinite [10]. According to the DRI, some of these clays exhibit shrink-swell properties whendried and wetted, which may contribute to loosening of surface crusts that in turn may liberatesediment for wind transport. This high concentration of small clay, silt, and sand particles makefor a firm and sturdy surface which will offer good strength and stability for stakes driven into it.

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Particle Size Weight Percent

Sand

Silt

Silt

Clay

> 2.46 3.1

0.591 - 2.46 10.4

0.118 - 0.591 21.2

< 0.118 65.3

Table 2: Typical particle size and distribution of Black Rock Playa [10]

According to WeatherForYou.com, the Black Rock Desert Wilderness received a total of 9.57inches of precipitation during 2012 and had received a total of 5.88 inches during 2013 as ofJuly 31, 2013 [M5]. According to the Western Regional Climate Center (WRCC), the averagetotal precipitation over the period of record from 1/17/1948 to 11/8/2012 in the Black RockDesert area was 7.46 inches [14]. This is highly advantageous for the implementation of theRLS. The RLS, which has been designed for this project, incorporates six 0.75 inch diameter, 24inch long stakes that will be driven into the ground to give the launch rail system its stability.Thus, it is imperative that the playa surface be hard and durable during the launching of the high

powered rockets. While rainfall can be difficult to deal with during launch week due to a muddysurface, a few weeks of dry weather provides a durable surface with an abundance of hard,damp clay a few inches below the surface. From past experiences, objects driven into this clayare very sturdy and difficult to remove. The soil of Black Rock will provide excellent stability forRLS.

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IMPLEMENTATIONMANUFACTURING METHODMost of the parts for this assembly are fairly simple and require little to no manufacturing toproduce. We have access to the UW ME student machine shop, the UW physics machine shop,

and Garrison Burger has been given permission to access of his companys machine shop,which conveniently has a water jet cutter.

All fasteners, spacers, bearings, etc. will have been specced and will be bought directlyfrom suppliers.

All sheet metal pieces will be cut out of large sheets by water jet. Those that need to bebent will be done with a bend press and a jig set to the correct angle bend.

The aluminum extrusions will almost all be recycled with only two being bought. Severalpieces will need to be cut via band saw and many will need polishing with the belt sander.

The stakes will be made out of steel rod bought from the supplier. Threads will be cut vialathe, and the stake tip will be honed using a grinder.

The only parts of this operation that will need require sizable effort will be the rod holders. The

single rod holders are far too expensive to purchase individually; the body will be made on themill out of a solid block of aluminum, and the quick releases will be bought separately. Thedesign is based closely on that sold by the supplier, but in manufacturing them in this way thecost is reduced nearly tenfold. The double rod holders will be manufactured in a similar mannerto the singles, and it will simply use more resources.

ASSEMBLY METHODThe goal of this design is to leave as little assembly as possible to the end user. By planning foras many pieces as possible to stay together permanently, the likelihood of the structure beingproperly assembled is increased. The same subcategories outlined at the beginning of thedesign introduction will be assembled before delivery, and will stay that way.

The most straightforward starting point is the base. The four pieces of extruded aluminummaking up the square will be fastened together using McMaster-Carr part 47065T155. If it isaffordable some method of adhesive could be added as well. The triangular pieces whichengage the stakes will be bolted onto the T-Slots along with the vertical triangular pieces thatengage the rotating rod. The stakes and their nuts will need to be stored separately, andinstalled on site. The bearings will be added in this stage, and permanently fixed with a forcedfit.

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The backside rails can be assembled to the point where they have the extension rods attachedto them, and will be completely assembled with the main structure on site. Their rod holders willbe connected in the same way as all the others, and the extension rod will be inserted andbolted in place.

Figure 27: Backside Rails Assembly Explode

The support base and support rails will require most of their assembly on site, but it will beminimal, and once per trip granting only one angle of launch be necessary. The two support railswill have their rod holders attached permanently, and the choice can be made whether to keepthe support bar connected permanently or not. The support base can have the sleeve bearingsinstalled into the triangle supports, but the rest will be done on site.

Figure 28: Support Assembly Explode

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TRANSPORTATION METHODThe sub assemblies should all be relatively flat or small. This will allow them to compactly fit inthe back of a standard cargo van and allow for easy set up at the launch site. The followingitems should be loaded:

(1) Base plate assembly

(2) Backbones

(2) Side extensions

(2) Backside Rails

(5) Rods

(2) Support Extrusions

(1) Support Connector

(2) Support Stake Plates

All necessary screws, fasteners, and pinsSome tools will be necessary to assemble and disassemble the RLS. These tools are listedbelow:

Pipe Wrench

Hex Drivers Sledge Hammer

USER INSTRUCTIONS

LAUNCH SITE ASSEMBLY

First, a suitable launch location should be determined. The location should be at least 500 feetfrom the base camp, and on level ground. Most of the ground should already be fairly flat, sofinding a spot should not be difficult. The base assembly should be laid on the ground in thedesired location. The stakes should be partially driven into the ground through the holes in thebase assembly in order to determine their location. The assembly should then be removed andthe stakes driven the rest of the way until the threads are at the surface of the ground. Thebottom nuts should then be threaded onto the stakes, and the base assembly can once again

be lowered into position. The nuts should be adjusted until the platform is level and thensecured in place by the top nuts. When removing the stakes, they can be grasped at the topwith a pipe wrench and twisted free from the earth.

While the base assembly is being secured in place, the main frame can be assembled. Thebackbones should be attached by the two rods through the rod holders. The backbones shouldbe relatively symmetric on the rod, though the location does not need to be precise. The backrails can then be slid into the dual rod holders.

Once the main frame is assembled it can be attached to the base using the lower rod and thehinge plates. Once the frame is attached and the clevis pins are in place, the frame can be liftedto a vertical position. Once vertical, the support rails can be attached to the frame at the upperrod, and to the lower support rod. The rod should then be positioned such that the frame sitsvertical (or at the desired launch angle. Its stakes can then be driven and the rod secured in asimilar fashion to the base assembly. Examples of various launch angles and the loadingposition are shown below in Figure 29. Although a blast plate is not integrated in the RLSdesign, should it be determined that one is required the plate from the previous system can beplaced on the ground beneath the rocket.

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Figure 29: Launch and Loading Positions

ROCKET LOADING

To load a rocket for launching, first the system should be lowered to the horizontal loadingposition. The support rails should be detached from their rod, and the frame carefully lowered.

The backbone separation should then be adjusted such that the backbone rails contact therocket body at least 90 apart. This will ensure that the points of contact are evenly spacedenough hold the rocket securely. Care should be taken that the backbone rails are not spacedsuch that the fins may intersect with the sheet metal pieces. The rocket can then be slid downthe backbone rails. Rockets four inches wide and larger must be oriented with one fin vertical,between the back rails. The nylon sliders will constrain the fin and keep the rocket from rotatingwithin the frame, ensuring that no fins will collide with any section of the frame. Rockets twoinches in diameter must be oriented with one fin between the backbone rails. Collision with theframe should not be possible for rockets of this diameter in this orientation. Rockets that arethree inches in diameter may be oriented in either direction, depending on the users preference.Once the rocket has been loaded into the frame, the back rails can be extended until theycontact the rocket body, and then tightened. The rails should not clamp the rocket tightly but

hold it in place while maintaining the ability to slide freely.Once the rocket is in place, the frame can be raised to launch position, and the support railsreattached to their rod. The rocket can now be prepared for launch following standard rocketryprocedures.

CARE AND CLEANING

During assembly and operations of the RLS care should be taken to not over-tighten fastenersor strip the heads. Most fasteners that will be used on a regular basis will have adjustable

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handles so this should not be as much of a concern as the last design. Throughout the use ofthe RLS, the system will accumulate a lot of grime from rocket exhaust as did its predecessor.This is an unavoidable outcome, but can be accounted for by proper cleaning. All the surfacesshould be wiped down periodically during use, and at the very least before putting the system instorage for the rest of the year. It should be noted that the sooner after the launch the cleaningtakes place, the easier it will be.

SAFETY PRECAUTIONSBeyond standard rocketry safety, there are only a few safety precautions. Care should be takento not pinch fingers and skin when tightening components. Before launching a rocket, it shouldbe verified that the system is completely secure. All fasteners should be tight, and the systemshould be rigid and fixed. Should extreme winds pick up, the frame can be lowered to theloading position to minimize wind forces on the structure.

FUTURE WORKTo make the RLS a reality, several next steps must be taken. First, drawings for all machined ormodified parts must be made. Since the team will be making these parts and not an outside

shop, the drawings do not need to be to top-level standards, just good enough so that theperson making the part can get it right. Next, all materials and components must be purchased.The list of items to be purchased is shown along with the cost chart in Appendix D. Most rawstock will be purchased from OnlineMetals.com. This will save time and money since they havea warehouse in Seattle where orders can be picked up. There will be no shipping costs andmaterial will be in-hand faster. Other components will be ordered from McMaster-Carr which iswell renowned for speed and quality. Once all stock is in hand, the team will machine the partsaccording to the manufacturing plan. When all the parts are finished, the RLS subcomponentswill be assembled. The whole assembly will be put together for a test fit before delivering to thecustomer.

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REPORT SUMMARYAlthough the launch rail systems from previous years have fulfilled their functional requirements,they have done so at the cost of much wasted time and frustration. The previous launch railsystem used by the ESS 472 class during their trip to the Black Rock desert during the Winter of2013 served its intended functions, but did so with a multitude of issues. Throughout thiscapstone project, the design of a new launch rail system was guided by the intent to resolve theissues presented by the previous system.

The previous launch rail system presented problems when setting up the rockets. Due to therebeing rockets with either three or four fin arrangements, and diameters that ranged from two tosix inches, the launch rail needed to be easily adjustable when in fact it proved to be verydifficult to adjust. Too many degrees of freedom caused the process of getting the launch railinto the necessary configuration to be a gigantic hassle. As many as 24 screws need adjustingprior to each launch. The previous design incorporated structural members that were designedto be unnecessarily long. This allowed for the development of large bending moments on the

joints leading to slipping. The previous design was not designed with ease of loading the rocketsin mind. Tall, heavy rockets made for a very difficult and time consuming rocket loading process.

Field adjustments were attempted in order to make the process easier, but instead just creatednew problems. A poorly designed stabilizing and foundation system meant the launch rail wasboth unsteady and awkward to readjust. In one case, components interfered with each othermaking it difficult or impossible to get the system into the necessary configuration. Thecombination of all these issues gave rise to the need for a greatly improved system which iswhat this project was designed to accomplish.

The design process for the new launch rail system begun with the consideration of numerousissues presented by the previous design. Each individual issue was isolated and possiblesolutions were considered. Once each issue was identified and solutions presented the bestsolutions were selected based on a ranking criteria. This was done according to their simplicityand effectiveness in solving the problem, and how well they contributed to fulfilling the function

requirements. The possibility of reusing parts and features from the previous launch rail wasconsidered. Parts that had performed well, such as the square frame made of one inch T-slottedextrusions, were reincorporated into the new design. How well the individual improvementscontributed to improvement of the overall systems was one of the most important factors inconsidering which ideas to keep and which to reconsider. There were many proposed solutionsthat were later scrapped once deemed ineffective (e.g. bent sheet metal to act as the frame forthe system).

The newly designed launch rail system has made adjusting for different rocket sizes andconfigurations profoundly simpler and more convenient. The design is far more stable andsturdy. Loading the rockets into the system has been made far less difficult as well. All screwsrequiring loosening for adjustment of the system have been replaced with a quick release clamptightening mechanisms. The number of adjustment points needed to reconfigure the frame hasbeen reduced from twenty four to twelve, only four of which requiring adjustment when therocket is loaded. The entire frame has been redesigned so that the frame can be lowered into ahorizontal position. Once in this position, the rocket can be loaded easily. Then, utilizingleverage to assist with the lifting, the frame and rocket can be easily lifted back upright into avertical position. The rocket is held in place by adjustable arms that easily slide in and out toaccommodate different diameter rockets. Six, two foot steel stakes with threaded portions willbe slid through braces on the base of the rail frame and driven into the ground, secured to theframe by hex nuts. This ensures the frame is sturdy, level, and will not change position during a

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rocket launch. It should also be noted that if the next rocket is of the same size, minimaladjustment will be required, whereas the old design would have to be mostly undone, the rocketloaded, and all the adjustment points reconfigured.

The physical launch rail system has not been constructed as of yet, thus field test of the designperformance cannot be performed. However, structural analysis was performed on the systems

using SolidWorks SimulationXpress feature to predict the levels of stress and analyze areas ofconcern. The results of this analysis predicts that the total mass of the rocket and the systemapplied to the most crucial members of the structure, the factor of safety of the load bearingcomponents is close to 4.5. During a rocket launch large amounts of thrust are directeddownward by the rocket exhaust. However, past rocket launches and the conceptualization ofthrust dispersion in a fluids perspective show that nearly all of this force is directed on thesurrounding air, flowing around the structure rather than being directly applied. It is estimatedthat even the most powerful rockets launched by the ESS 472 class would only marginally lowerthe load bearing components factor of safety, if only for a fraction of a second.

The analysis results of Black Rock desert soil predict that soil conditions will be perfect forproviding stability and support for the rail system during launches. Thus far, during this year andlast, the Black Rock Desert playa has received above average precipitation. Past experienceshows that during the Spring, and several months to follow, following a year of heavy rain, theplaya surface is hard and relatively durable due to salt, sand and mud left behind by recentrainfall. Therefore the six steel stakes should provide ample support for the entire system.

A cost analysis of the entire system shows that the launch rail should cost only $469.13 tomanufacture. Costs have been cut down due to the use of recycled parts from the launch railsystem used in the previous year. Many of the parts required for the construction of this newsystem may very easily be manufactured in house rather than buying the parts pre-made. Thisalso contributes significantly to keeping the cost within the budget.

There were several lessons learned during the design process of this system. First, whenconsidering possible ideas, the decision must be made whether to start from scratch or to

attempt to utilize design concepts already in use and improve upon their functionality. Choosingthe latter is often preferred from an economic standpoint. Strong points of an existing designcan always be carried over into a new design. Existing parts can also be salvaged and recycledwhen starting from an existing design.

Another important lesson involves the care taken when making assumptions. This design reliesheavily on only two points to bear most of the systems weight. Although common sense oftenpredicts key structural points will provide enough support, much care should be taken to makeconservative assumptions. If there is any doubt, it would be wise to seek a second (moreexperienced) opinion. In fact a second opinion should be sought whenever possible. It can beeasy to become wrapped up in the design that certain flaws and oversights may be overlooked.Thus it is always advantageous to seek a fresh pair of eyes. These eyes may see somethingnew and may think of something only an outside perspective can see. This was taken to heart

with this project, and as much input from a diversity of backgrounds was consulted for designinput as possible. Putting these principles to use resulted in a stable, functional system that willlast for years to come.

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REFERENCES(1) Tom Benson. Brief History of Rockets.Grc.NASA.gov. FirstGov, Feb. 2, 2010. Web.

8/19/13. .

(2) Cliff Lethbridge. History of Rocketry. Spaceline. N.p. N.d. Web. 8/19/13.

(3) Mod.1847 2.25in.Hale Rocket Launcher. Confederatengineers.com. Confederate

Engineers, N.d. Web. 8/19/13.

(4) Rocket Principals. Abyss.uoregon.edu. Abyss, N.d. Web. 8/19/13.

(5) File:V-2 Rocket on Meillerwagen.jpg.Wikipedia.org. Wikipedia, N.d. Web. 8/19/13.

(6) Kennedy Space Center Launch Complex 39. Wikipedia.org. Wikipedia, N.d. Web.

8/19/13.

(7) Rod Pyle. NASAs Biggest Rocket Yet Aims for 2017 Test Flight. Space.com. Tech

Media Network, June 7, 2013. Web. 8/19/13.

(8) Tower Launcher. Caztek. Web. 8/21/13.

(9) Winglee, Robert. ESS 472/575: Rockets and Instrumentation. University of Washington,

n.d. Web. 8/8/13.

(10) Kenneth D. Adams, D. W. Sada. Black Rock Playa, Northwestern Nevada: Physical

Processes and Aquatic Life. Bureau of Land Management, May 24, 2010. Pg. 1.

Web. Aug. 8, 2013.

(11) About the Black Rock Desert Playa. Black Rock Desert. Friends of Black Rock High

Rock, n.d. Web. Aug. 8, 2013.

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http://blackrockdesert.org/about-the-black-rock-desert-playa/http://blackrockdesert.org/about-the-black-rock-desert-playa/http://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://courses.washington.edu/ess472/Lecture_Rocket_Dynamics.pdfhttp://courses.washington.edu/ess472/Lecture_Rocket_Dynamics.pdfhttp://www.space.com/21487-nasa-sls-biggest-rocket.htmlhttp://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39http://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39http://en.wikipedia.org/wiki/File:V-2_Rocket_On_Meillerwagen.jpghttp://abyss.uoregon.edu/~js/space/lectures/lec03.htmlhttp://www.confederateengineers.org/rocket-artillery.htmlhttp://www.confederateengineers.org/rocket-artillery.htmlhttp://www.spaceline.org/history/2.htmlhttp://www.spaceline.org/history/2.htmlhttp://www.grc.nasa.gov/WWW/k-12/TRC/Rockets/history_of_rockets.htmlhttp://www.grc.nasa.gov/WWW/k-12/TRC/Rockets/history_of_rockets.htmlhttp://blackrockdesert.org/about-the-black-rock-desert-playa/http://blackrockdesert.org/about-the-black-rock-desert-playa/http://blackrockdesert.org/about-the-black-rock-desert-playa/http://blackrockdesert.org/about-the-black-rock-desert-playa/http://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://www.blm.gov/pgdata/etc/medialib/blm/nv/field_offices/winnemucca_field_office/nca_pdfs.Par.30693.File.dat/Black%20Rock%20Playa%20DRI%20Report.pdfhttp://courses.washington.edu/ess472/Lecture_Rocket_Dynamics.pdfhttp://courses.washington.edu/ess472/Lecture_Rocket_Dynamics.pdfhttp://courses.washington.edu/ess472/Lecture_Rocket_Dynamics.pdfhttp://courses.washington.edu/ess472/Lecture_Rocket_Dynamics.pdfhttp://www.space.com/21487-nasa-sls-biggest-rocket.htmlhttp://www.space.com/21487-nasa-sls-biggest-rocket.htmlhttp://www.space.com/21487-nasa-sls-biggest-rocket.htmlhttp://www.space.com/21487-nasa-sls-biggest-rocket.htmlhttp://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39http://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39http://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39http://en.wikipedia.org/wiki/Kennedy_Space_Center_Launch_Complex_39http://en.wikipedia.org/wiki/File:V-2_Rocket_On_Meillerwagen.jpghttp://en.wikipedia.org/wiki/File:V-2_Rocket_On_Meillerwagen.jpghttp://abyss.uoregon.edu/~js/space/lectures/lec03.htmlhttp://abyss.uoregon.edu/~js/space/lectures/lec03.htmlhttp://abyss.uoregon.edu/~js/space/lectures/lec03.htmlhttp://abyss.uoregon.edu/~js/space/lectures/lec03.htmlhttp://www.confederateengineers.org/rocket-artillery.htmlhttp://www.confederateengineers.org/rocket-artillery.htmlhttp://www.confederateengineers.org/rocket-artillery.htmlhttp://www.confederateengineers.org/rocket-artillery.htmlhttp://www.spaceline.org/history/2.htmlhttp://www.spaceline.org/history/2.htmlhttp://www.spaceline.org/history/2.htmlhttp://www.spaceline.org/history/2.htmlhttp://www.grc.nasa.gov/WWW/k-12/TRC/Rockets/history_of_rockets.htmlhttp://www.grc.nasa.gov/WWW/k-12/TRC/Rockets/history_of_rockets.htmlhttp://www.grc.nasa.gov/WWW/k-12/TRC/Rockets/history_of_rockets.htmlhttp://www.grc.nasa.gov/WWW/k-12/TRC/Rockets/history_of_rockets.html


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(12) Playa. GeologyPage. Geology Page, July 2, 2013. Web. Aug. 8, 2013.

(13) N.a. WeatherForYou.com. WeatherForYou.com, LLC. Web. Aug. 8, 2013.

(14) N.a. wrcc.dri.edu. Western Regional Climate Center. Web. Aug8, 2013.

(15) Joe. Adjustable Launch Tower. Gianleaprocketry.com. Giant Leap Rocketry. Web. 2

Aug. 13.

(16) Aluminum 6061 T-651. Asm.matweb.com. Aerospace Specification Metals Inc. Web. 2

Aug. 13.

(17) 304 Stainless Steel. Asm.matweb.com. Aerospace Specification Metals Inc. Web. 2

Aug. 13.


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APPENDICESAPPENDIX A:MATERIAL PROPERTIES

ALUMINUM 6061-T6[16]

Tensile Strength

Yield Strength

Youngs Modulus

Shear Modulus

Shear Strength

45000 psi40000 psi

10000 ksi

3770 ksi

30000 psi

4140COLD DRAWN STEEL [17]

Tensile Strength

Yield Strength

Youngs Modulus

Shear Modulus

73200 psi

31200 psi

28000 ksi

12500 ksi

APPENDIX B:ROD SIZING37.5 lbf37.5 lbf37.5 lbf37.5 lbf

RA RB

4.56 in 8 in 8 in4.91 in 4.56 in

2.375 in 2.375 in25.25 in

30 in1in

A

Setup:

E =10.49 psi

! =0.3333

nd =2

Fy =150 lbf

Plane Stress Von-Mises method

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! ' =Sy

nd=

45000 psi

2= 22500 psi

22500 psi =4724.99

d3"#$

%&'

2

+ 3393.43

d3"#$

%&'

2

d= 0.596 in

From Table A-17 [21], next standard choice is 5/8 in. 1 in will work fine and fit the standard tubeholders.

!' =4724.99

13"#$

%&'

2

+ 3 393.43

13"#$

%&'

2

=4773.876 psi

!' =Sy

n(n =

Sy

!'=

45000

4773.876=9.4

The factor of safety is 9.4.

APPENDIX C:LAUNCH SPEEDKinematic Equations

x= x0+ v

0t+

1

2at

2

v = v0+ at

Assuming launch accelerations of at least 5G (rocket requirement)

x=0m + 0 ms(.1s)+ 12 (5*9.81

m

s2 )(.1s)

2

x=0.25m

v = (5*9.81ms2 )(.1s)

v = 4.9 ms

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STOCK

Stock Length Quantity Price Subtotal From

.125" x 2" Aluminum Bar 8 2 $7.40 $14.80

http://www.onlinemetals.com/merchant.cfm?pid=1145&step=4&showunits=inches&id=997&top_cat=60

2.5" x 3" Aluminum Bar 2 1 $71.97 $71.97

http://www.onlinemetals.com/merchant.cfm?pid=12769&step=4&showunits=inches&id=997&t

op_cat=60

1" Aluminum Rod 6 1 $19.57 $19.57


1" Aluminum Rod 8 1 $24.69 $24.69


.25" x 8" x 8" AluminumSheet 4 $9.18 $36.72


.75" Steel Rod 4 3 $27.61 $82.83


4" x 3" Aluminum Bar 3 in 1 $16.56 $16.56


.5" Hexagonal NylonRod 48" 4 4 $5.51 $22.04

http://www.mcmaster.com/#nylon-hex-bars/=nzotzq

Subtotal $289.18

Total 469.13

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Mechanical Engineering Capstone Project, University of Washington

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Transcript of Mechanical Engineering Capstone Project, University of Washington