Low Shock Payload Separation System. Final Report. Team 2A: Amanda Crawford Christian Johnson Roberto Gonzalez Sage Pasternacki Garrett Wright

Transcription

1 Low Shock Payload Separation System Final Report Team 2A: Amanda Crawford Christian Johnson Roberto Gonzalez Sage Pasternacki Garrett Wright Project Sponsor: Orbital ATK Sponsor: Orbital ATK Client Contact: Steven Hengl Faculty Advisor: David Willy Instructor: David Wily DISCLAIMER This report was prepared by students as part of a university course requirement. While considerable effort has been put into the project, it is not the work of licensed engineers and has not undergone the extensive verification that is common in the profession. The information, data, conclusions, and content of this report should not be relied on or utilized without thorough, independent testing and verification. University faculty members may have been associated with this project as advisors, sponsors, or course instructors, but as such they are not responsible for the accuracy of results or conclusions.

2 Contents DISCLAIMER 1 1 Background Introduction Project Description Original System 4 2 Requirements Customer Requirements (CRs) Engineering Requirements (ERs) House of Quality (HoQ) 6 3 Existing Designs Design Research System Level Existing Design #1: Antares Existing Design #2: Pegasus Existing Design #3: Minotaur Subsystem Level Original Subsystem: Orbital ATK Subsystem #1: RUAG Subsystem #2: Planetary Systems Corporation Subsystem #3: NanoRacks Separation Systems 14 4 Considered Designs J-clamp design Polymagnet System Chosen Design: The Bolt Proposed Design 25 REFERENCES 28 2

3 Appendix A 30 Appendix B 37 K.E. 40 P.E. 40 E s 40 3

4 1 Background 1.1 Introduction Orbital ATK, a global leader in aerospace and defense technologies, builds and delivers space systems ranging from satellites to military defense systems. Their main products include launch vehicles and satellites. Orbital ATK was created when two companies, Orbital Sciences Corporation and ATK, merged to form Orbital ATK, employing approximately 12,000 employees worldwide [1]. Orbital ATK is divided into three main operating groups: Flight Systems Group, Defense Systems Group, and Space Systems Group [1]. This project focuses on Orbital ATK s three main launch vehicles: Antares, Pegasus, and Minotaur [2]. Currently, Orbital ATK purchase their low-shock payload separation systems to other companies. As there are many different systems on the market, the availability is not the problem. Our client would like to bring the production of these systems in-house in order to save money and have more control over the production process. This plan addresses the contemporary issue of manufacturing outsourcing. Orbital ATK has an ultimate goal of vertically integrating their company. 1.2 Project Description Orbital ATK has commissioned this capstone team to design a low-shock payload separation system that can be built in-house at a fraction of the cost compared to what their competitors manufacture. Orbital ATK has provided us with the following goals: [1] Work with Orbital ATK mechanical engineers to understand the needs and desires of the delivered project. [2] Survey commercially available separation systems. [3] Develop design concepts that meet all requirements. [4] Perform trade studies to down select to a single design. [5] Manufacture a prototype. [6] Provide Orbital ATK with PDR and CDR presentation; and Final product will include design, analysis and manufactured prototype. 1.3 Original System The three main launch vehicles, Antares, Pegasus, and Minotaur, are explained more in depth in section 3 of this paper. This team is designing a low impact separation mechanism. This team compared 4 different separation systems: Orbital ATK s 38 separation system, RUAG PAS 381S, Planetary Systems Corporation Motorized Lightband, and the NanoRack separation system. The structure, operation, performance, benefits, and deficiencies are explained in detail in section 3. 2 Requirements Orbital ATK has given our team a set of customer requirements discussed in section 2.1. The customer requirements were given weights based on how important they were to the customer. Engineering requirements, discussed in section 2.2, were then determined based on the customer requirements and given quantifiable values as goals for the design of our system. 2.1 Customer Requirements (CRs) Each customer requirement was assigned a value from 0 to 5 based on their level of importance. 4

5 Table 1: Customer Requirements Customer Requirements Weighting Justification Low Shock 5 One of the main objectives of this project requires that we create a system that will not impart excessive amounts of vibration to the payload being released. As such, low shock has been given a high priority and will be one of the main focuses throughout the project. Low relative cost 4 Orbital ATK s motivation for creating their own low shock payload separation system includes saving money, and because of this, the cost of the system must be kept to a minimum. In-House manufacturability 3 Orbital needs to be able to manufacture the chosen design at their facility. However, Orbital ATK has many manufacturing resources available to their use. As such, it has been given a lower priority. Compatible with existing payload systems 5 Compatibility has been given a weight of 5. The chosen design must be able to function with existing systems. Due to this face, a high priority has been given to compatibility. No debris upon separation 2 Debris upon separation, while important, allows for an easy design alteration, and because of this debris has been given a low priority. Withstand stresses during flight 5 As low shock is the ultimate goal, the ability of our design to withstand the forces encountered during flight directly relates to the success of the separation system. Electrical pulse to Signal Separation 3 The signal to initiate separation, as outlined by the client, requires an electrical pulse. This requirement has been given a medium priority because most systems benchmarked are actuated electrically, meaning that the initial signal would be electric. 2.2 Engineering Requirements (ERs) The engineering Requirements, drawn from our customer requirements, give quantifiable values as targets for the performance of our design. The requirements and their respective tolerances are outlined in the table below. 5

6 Table 2: Engineering Requirements Engineering Requirements Target/Tolerance Rational Can be stored and functional for up to 90 days 90 days This requirement is to allow for the separation system to be used if the original launch is delayed. Temperature range -10/75 C From the problem statement we were given, this was the minimum and the maximum expected range of temperatures that the separation system is going to reach. Immune to environmental conditions <90% humidity Immunity to environmental conditions is to ensure that the system will not rust when it is in stored in a container. Success rate 100% The desired success rate was determined through the benchmarking of comparable systems. Withstand bending load 28,085 in-lbf This requirement was given by the client to show the expected bending load Withstand shear loads 1,630 lbf This requirement was given by the client to show the expected shear loads. Withstand axial loads 2,315 lbf This requirement was given by the client to show the expected Axial loads. Variable separation force ft-lbf The Variable Separation Force is required by the client so they can change the force separating the systems depending on the payload Tipoff angle <1 degree/sec Tip-off angle is the rate at which the centerof-gravity of the payload rotates upon separation. Our goal is to keep it to a minimum. Existing system compatibility 15 in. diameter with 24 ¼ in fasteners This is to ensure that the systems will be able to be used by the client for its intended use. Factor of safety N = 1.25 This is to ensure that the payload will not break by the forces it experiences when being launched. 2.3 House of Quality (HoQ) This team has organized the customer requirements and the engineering requirements into a House of Quality in order to evaluate the absolute technical importance (ATI) and the relative technical importance (RTI). The ATI assigns a numerical importance value based off of how each engineering requirement affects or contributes to each individual customer requirement. The RTI simplifies these numbers and chronologically orders each need to signify the sequential importance. 6

7 Table 3: House of Quality 3 Existing Designs This capstone team has identified three launch vehicles that could implement our designed separation mechanism: Antares, Pegasus, and Minotaur [2]. 3.1 Design Research Design research was conducted using predominantly online resources, supplemented with information provided by our client contact. Exact performance characteristics are difficult to obtain given the competitive nature of the aerospace industry, however, any relevant information that could be obtained is presented in sections System Level Orbital ATK has three main launch vehicles. Two are for any company that needs to send up a small-medium sized payload. The third is strictly for government use. Figure 1 shows (from left to right) the Antares, Pegasus, and Minotaur Launch Vehicles on their launch pads [2]. 7

8 Figure 1: Antares, Pegasus, and Minotaur Launch Vehicles, respectively [2] Existing Design #1: Antares The Antares was designed to resupply the International Space Station (ISS) but has also been used in commercial, scientific, and defense applications [3]. There have been 5 total launches since April 2013 with 1 recordable failure [4]. Figure 2 shows the breakdown of how each component of the rocket separates during ascension into orbit [5]. Figure 2: Antares Separation Process [5] The Antares is a two stage rocket used to send medium payloads weighing 7,000-9,000 kilograms into orbit. It is 9.9 meters long by 3.9 meters in diameter, and weighs 290,000 kilograms [5]. Major components include the avionics assembly, Aerojet engines, payload fairing, payload interface system, and separation system [3]. 8

9 Figure 3: Antares Vehicle [5] A standard 62-inch bolted payload cone offers a wide variety of separation systems to be integrated into the vehicle. The most popular used for the Antares is the RUAG Marmon Clamp Separation System. Figure 3 illustrates where each component is on the launch vehicle [5] Existing Design #2: Pegasus In 1989, Orbital ATK unveiled the Pegasus. This was the first commercially developed launch vehicle, and provides an opportunity for companies to send their payloads into orbit. This is the only launch vehicle Orbital ATK has that is launched horizontally using a carrier aircraft [6]. There have been 42 total launches with 3 recorded failures [7]. Figure 4 shows how the rocket separates during each stage while launching into orbit [8]. Figure 4: Pegasus Separation Process [8] The Pegasus is a three stage rocket weighing 23,000 kilograms. It is 17 meters long with a diameter of 1.5 meters. It can carry payloads of up to 450 kilograms into low Earth orbit [8]. The 9

10 Pegasus has nine crucial components: avionics assembly, lifting wing, aft skirt, payload fairing, payload interface system, three motors, and the separation system [6]. Figure 5: Pegasus Vehicle [8] The Pegasus uses two different separation systems; one is 97 cm while the other is 56 cm in diameter. Both systems are manufactured in-house by Orbital ATK. Figure 5 illustrates where each component is on the launch vehicle [8] Existing Design #3: Minotaur The Minotaur family consists of 6 different rockets and is exclusively used by the United States Government [9]. The Minotaur, starting in 2001, has completed 25 missions with a success rate of 100% [10]. Figure 6 shows the breakdown of how each component of the rocket separates while launching into orbit [11]. Figure 6: Minotaur Separation Process [11] As the designs of the family progressed they got larger; the Minotaur I is the smallest and the 10

11 Minotaur VI is the largest. The Minotaur family is designed to launch payloads weighing up to 3,000 kilograms [11] Major components include the avionics structure, payload adapter cone, motors, motor adapter cone, payload fairing, and separation system [9]. 3.3 Subsystem Level This capstone team researched and evaluated a current subsystem used by Orbital ATK and three subsystems designed and manufactured by competitors. The subsystems evaluated are the Orbital ATK 38-inch separation system, the RUAG PAS 381S, the Planetary Systems Corporation Motorized Lightband, and the NanoRacks separation system. To further breakdown the systems that the team researched, a hierarchy functional decomposition was constructed to help understand the key functions of a separation system as provided below. Figure 7: Hierarchy Functional Decomposition The four main functions of a separation system are attachment, separation, incoming signals, and actuation. Once the team figured out what the key functions were of these systems, the team theorized methods to perform the four functions. For example, for attachment threads, magnets and friction some methods of attachment that could be used. As for the incoming signals, this branch was looking at the different methods at which the separation system will be able to take in information of the flight mission and know when to initiate the separation procedure Original Subsystem: Orbital ATK In researching for our project and upon the request of our client, we researched the companies whose products are similar to that which we set out to design. In our research we came across Orbital ATK s own records and found their own system. The Orbital ATK 38-inch separation system was designed for lighter payloads. The main separation system required the system to break the restraint for the payload to jettison Orbital ATK 38 Separation System Structure and Operation Orbital ATK s 38 separation system is a single stage, two-part system that uses a V-band clamp, also known as a Marman clamp, to secure the payload and the launch vehicle rings together [9]. In order for the system to initiate its separation process, two bolt cutters would cut the V-band clamp in two places allowing the payload to separation from the launch vehicle [9]. 11

12 The cut V-band sections would be caught in catches to reduce fly away debris from the system [9]. Figure 7 below shows a side view of Orbital ATK s system. Figure 8: Orbital ATK 38" Separation System [9] Orbital ATK 38 Separation System Performance and Benefits As of August 2015, this system has flown in over 40 successful flight missions [9]. For this design three benefits were pointed out by our client when the team inquired about the system two of which being simple and reliable. The main benefit is that the design can be manufactured inhouse where the other systems they use are made from other companies. However, with benefits come drawbacks and this system had some Orbital ATK 38 Separation System Deficiencies The Orbital ATK 38 separation system is has deficiencies that came with the system construction and operation. During a meeting with our client, head mechanical engineer Steven Hengl, about their company's system two main deficiencies were pointed out. First, the system is heavy compared to other systems added additional strain on the launch vehicle compared to their competitors. The goal for these systems is to have minimal shock generated during the separation process. Next, Orbital ATK s system generates high amounts of shock during the separation because of the bolt cutter cutting through the restraining clamp holding the two rings together. With this new knowledge, we began research into other companies separation systems that are generate little to no shock Subsystem #1: RUAG The first system that drew the attention of the team was the separation system from RUAG. From the systems we researched, a reoccurring trend was appearing. RUAG fits in this trend by using a V-band clamp to secure the payload. The V-band clamp commonly is a flexible metal band with a V shaped notched where the two parts of the system are secured together RUAG PAS 381S Structure and Operation The RUAG PAS 381S 15-inch single stage, two-part module separation system that uses a V- band clamp to hold a payload ring to a main vessel ring [12]. Once the vessel reaches the optimal separation height the system initiates. The motor loosens a circular lightband holding the payload ring and the hub ring together. Once the lightband is loosened for the payload to separate, springs at strategic positions on the hub ring push the payload away from the vessel thus, completing the separation. In 2012, the ring structure underwent refinement to reduce critical stress zone on the clamp and the rings [13]. As presented below in figure 8, a slight riser was added in the construction of the contact locations of the rings to reduce rotation and lateral movement prior to the systems separation [13]. 12

13 Figure 9: PAS 381S by RUAG [12] Figure 10: RUAG Modification [13] RUAG PAS 381S Performance According the RUAG, throughout this system's operation it has been used in 550 in-orbit separation. Of those, the system has had a success rate of 100% [13]. 13

14 3.3.3 Subsystem #2: Planetary Systems Corporation The second system that was analyzed is a system from Planetary Systems Corporation (PSC). This system is called the Planetary Systems Corporation Motorized Lightband and is represented in figure 9. This also fit the trend of using a V-band clamp to secure the payload to the launch vehicle and similar in structure as the RUAG system; however, there is on difference PSC Motorized Lightband Structure and Operation The Mark II Motorized Lightband (figure 9) is a single stage, two-part assembly that utilizes a V-band clamp similar to the PAS 381S; however, Planetary Systems Corporation refined the design to reduce the chance of debris upon separation. PSC inverted the V-band clamp so the clamp is on the inside of the system, increasing controllability of the ring upon separation [14]. The Mark II operates in the same manner, but instead of loosening the clamp the Mark II tightens the V-band clamp releasing the payload from the vessel [14]. Upon further research, no information was found about any subsequent refinements to this system. Figure 11: Mark II Motorized Lightband by Planetary Systems Corporation [14] PSC Motorized Lightband Performance According to the records of Planetary Systems Corporations out of 45 flights, this system has a success rate of 100% [14] Subsystem #3: NanoRacks Separation Systems The third system our team researched is called NanoRacks Separation System (NRSS). This system does not have V-band clamp in its system; however, even though this system does not have a V-band clamp and is currently in use on the International Space Station (ISS) there are still systems that the team feels could prove useful for our system NanoRacks Separation Systems Structure and Operation As represented in the figure 10, similar to the PAS 381S and the Mark II, the NRSS is a two-part separation system where one half remains with the payload after the separation. The key difference the NRSS has from the Mark II and the PAS 381S is the use of separation switches over the V-band clamp [15]. The NRSS has three sets of three springs that are compressed when the payload ring is attached to the launch platform [15]. When the separation switches are triggered the payload will release from the launch platform allowing the springs to stretch out, pushing the payload was away. 14

15 Figure 12: NanoRacks Separation System [15] NanoRacks Separation Systems Performance Since this was implement last year no data of the success of the system has been released to the public. 4 Considered Designs In order to narrow down our designs, we first put every design into a PUGH chart (as seen in Appendix B1). In the PUGH chart, entered three designs that are currently on the market already. We selected the Planetary Systems Corporation system as our datum because it is what Orbital ATK currently uses for most of their payload launches. We compared each of our designs the one Orbital ATK currently uses and gave a design a (+) sign if we felt the design exceeded our datum, a (-) if we felt that the datum was better, or a (same) if we felt it was equal to the datum for each of the engineering requirements. Based on our client s request, we eliminated the systems currently on the market based on weight, cost, or complexity. The designs that made it through our PUGH chart included the Polymagnets system, the Internal Locking Clamp System, the Bolts system, the Rubber Band Contracting System, and the J-Clamps system. We further evaluated these systems with a decision matrix. The client wanted us to analyze the systems from different directions to really understand the components and the importance and reliance each part has on the other. Instead of doing a typical decision matrix we did a chart comparing the different systems using criteria we could analyze based on Orbital ATK's expectations to narrow our decision down further to three potential final designs. For the criteria of this chart we chose material homogeny, material cost, in-house manufacturability, potential weight, system complexity, separation force modulation. We gave specific values to each system based on how much material each system uses, how many moving parts it has, and the feedback we received from our client. Orbital ATK's main focus for this was the system was simple and could be manufactured in house easily. For the next phase our client wants us to do calculations to analyze the forces, vibrations, actual weight, energy required, and EMF values to come up with a final design. 15

16 Criteria W. T. Internal Locking Clamp Bolt Table 4: Decision Matrix Rubber Band System J-Clamps Press Band Polymagnets Score W.S. Score W.S. Score W.S. Score W.S. Score W.S. Score W.S. Material Homogeny Material Cost In-House Manufacturability Potential Weight System Complexity Separation Force Modulation Total Orbital ATK Ranking 4.1 J-clamp design The J-clamp design was one of the 3 designs identified by the decision matrix. The J-clamp operates by using eight J-clamps mounted on the launch vehicle side of the system to secure a ring on the payload portion. To release the payload, a rotating plate with a linkage system attached to it, actuates the J-clamps. As the J-clamps rotate through their range of motion they unlatch the payload. After the payload is unlatched, the clamps continue to rotate until the long end of the J is in contact with the payload side of the mechanism, at which point the clamps become a lever and thrust the payload away. Figure 13: J-Clamp System Model The team has identified multiple advantages, first, the lever action of the clamps allows for the elimination of springs. Because of the use of the motor, it is possible to modulate the rate force 16

17 with which the payload is pushed away with. Another advantage to the system is that the clamps work simultaneously, meaning that the tip off angle can be easily controlled. The use of the central plate for actuation of the clamps mean that redundancy can easily be built into the system by adding a second motor at the plate. The Most important disadvantage to this system identified through meetings with the client is the complexity associated with the linkage system. With more moving parts, the likelihood of failure due to one of the parts malfunctioning increases. Another thing to keep in mind is the energy required to operate this system using the motor for both the separation and the push could mean that too much energy is required to operate this system. Future work on this system will be focused on decreasing part counts as well as analyzing how much energy will be required to operate the entire system. 4.2 Polymagnet System Polymagnets is a new approach in the field of magnetics. This technology, originally from Alabama, prints the two magnetic poles onto one face of the metal making a magnetic field focus on one side of the magnet. By printing the two different poles onto one side, the magnet utilizes more of the magnet field for attraction and repulsion. The Polymagnet system uses 12 matching rare earth metal (NdFeNi) magnets that are designed to attract when rotated to a specific orientation and release when rotated away from the latched orientation. Once the magnets release the springs will push the payload away. One of the advantages to the Polymagnet system is that the magnets could be, potentially, very strong. Rough calculations pointed to the magnets being much stronger than traditional magnets of comparable size. Another advantage to the Polymagnet system is that it the repulsion that comes from unlatching the magnets is slowly applied, potentially resulting in very low shock. Figure 14: Polymagnet System Model Orbital ATK is hesitant to use magnets as a means of securing payloads because it is an untested system, no other company uses magnets in this sort of application. Another concern Orbital ATK had for this design was the reliability of the linkage system used to rotate the magnets simultaneously. Orbital ATK was also concerned that the electromagnetic field produced by the magnets would interfere with the sensitive electronics in the payload. The magnets also collide together when first being mated which raises the question of safety that needs to be addressed. As of right now, tests on a latch Polymagnet demo set is in progress to check the validity of the 17

18 design to engineering requirements and Orbital ATK standards. 4.3 Bolt design The Bolt design utilizes threads to separate the payload from the launch vehicle. This design consists of three main components. There are two internally threaded rings, one mounting to the payload, the other mounting to the launch vehicle. The only difference between the two is that the one mounted to the launch vehicle is two inches long while the one mounted to the payload is an inch long (the silver parts in Figure 15). The third component is an externally threaded screw (red part in Figure 15), that is screwed down into the bottom base one inch. The top payload side of the system is then torqued onto the screw until the faces of the two rings meet. To separate, a motor will rotate the screw counterclockwise completely down into the launch vehicle side of the system. Once the screw is in the launch vehicle portion, this will allow the springs to take control and push the payload away safely and uniformly. Figure 15: Bolt Design Model This design was ranked first by our client based on the simplicity of the design. The major advantage to this design that our client identified was it only has three components and one moving part. Less things moving means that there is less to go wrong. Our client identified three disadvantages: the threads potentially binding when a shear force from the launch is applied to the system, the potential of the payload rotating with the screw, and the payload having a high tip off rate caused by the moment created when the last thread disengages. Moving forward, the focus will be to address these disadvantages. One way proposed to make the system stronger and prevent the threads from binding was by adding six small half inch cones along the ring of the internally threaded components. These cones are tapered by 15 for added strength. They also serve as a fastening tool to keep the payload from spinning when the screw rotates counterclockwise. To solve the large tip off angle we will make the threaded component have four to six threaded sections to eliminate the moment caused by the disengagement of the final thread. 5. Chosen Design: The Bolt After the down selection process the team chose the bolt design as the final design to develop into a prototype. To find which design was more feasible, we calculated the potential performance of each system. The results of the performance test indicated that the bolt design 18

19 was the most feasible. 5.1 Down Selection Process To select a final design, the three designs needed to be analyzed to see if there is one that meets the needs of Orbital ATK. Upon our Primary Design Review (PDR), Orbital ATK presented to the team their fears about each system and asked for tests and calculations to be done which could help narrow down to a final design. Each design had performance characteristics that needed to be determined before the team was able to make a decision. For the Polymagnet system, the most important questions in need of answering were whether or not the magnets could provide the locking force necessary to withstand the loads encountered during flight and if the EMF would harm the equipment onboard. With the J-clamp and the Bolt designs, the most important characteristic in question between the two was the potential reliability. In order to determine the most reliable, a reliability analysis was conducted Polymagnet Tests One of Orbital ATK s concerns with the Polymagnet design was induced magnetic field (IMF). Due to the fact that their cables and devices are extremely sensitive to the magnetic field, Orbital ATK requested the team to consider the Polymagnet s IMF. They wanted to see if it could meet their company tolerance of 10 V/m limit and how far the reach of the magnetic field is. To check the Polymagnet s validity for the design, a compass test was conducted which showed the magnetic field has a reach of three-inches from the center of the magnet. The team took the test one step further by asking Dr. Ciocanel to use his Gaussmeter to measure the Tesla of the magnet s center and edge. In addition, the team, with the assistance of Mr. Wood, took readings at increments of a half an inch from the magnets center to three inches away to confirm the results of the compass test. The results of the experiment are provided in Figure 16. Figure 16: Contour Plot of the Tesla Experiment The next test was to subject the magnets to torque and axial loads to determine the force required to pull them away. The magnets were secured in a vice with string wrapped around the outside of the magnet at their cardinal directions. For the torque and axial tests, the magnets were subjected to each test ten times. The data is displayed in Appendix B Table B2. With the torque and axial tests complete, the team conducted a ratio calculation (Equation 1) on the magnets to get the force a three-inch diameter magnet could hold. 19

20 Equation 1 Force 1 and Force 3 are the forces that the one inch and three-inch diameter magnets are expected to experience respectively. Area 1 and Area 3 are the contact areas that the magnets need to have to hold the forces respectively. From the data collected, the average axial load was calculated to be 4.87 lbf. This force was used as Force 1 in the equation above with its corresponding area of ft 2 to aid in finding the force that a three-inch diameter Polymagnet is projected to hold. The team agreed that assuming if the print density remained constant between the one inch and three-inch diameter magnets, resulting in a linear relationship, the expected force should be lbf. Multiplying the expected force by six magnets results in a projected clamping force is lbf, resulting in a system that is unable meet the axial load requirement Reliability Engineering and System Engineering for Bolt and J-Clamp After eliminating the Polymagnet design, the J-Clamp and Bolt design remained. Prior to beginning the analysis, the team remembered what Orbital ATK was concerned about with both the designs. The concept the Orbital ATK engineers were concerned about was the complexity. The team decided to consider the complexity of the two designs and connect that to the reliability of success for each of the systems Assumptions For the team to even begin on the reliability study, assumptions were required. The team decided to focus on the actual mechanism that was doing the separating of the system (all the components of the separation system excluding the payload and vessel rings.) The reason for this assumption is so both systems are analyzed on just their actuation components alone. The second assumption is the motor that will be used is the Mark II Motorized Lightband motor assembly. The reason for this is because Orbital ATK presently uses this system for most of their launches and has built a redundant system to make the reliability high (99.8% and 97.5% respectively) [16]. The third assumption is both systems are directly connected to the motor assembly to increase reliability. The final assumption is the power source is 100% reliable. The reasoning is for the separation system to operate, a program is created for this purpose and the team is only required to provide a mechanical system. With this assumption, when the program begins for separation, the system will get power to actuate Researched Reliability Percentages Table 5 elaborates on the main analyzed parts during this reliability study. Once these parts were selected by the team, an equation was determined that was appropriate for this study. To do this, an intense analysis was needed to look at the system method of actuation to separate. 20

21 Table 5: Reliability Values of the Analyzed Parts [16,17] Analyzed Parts Value Motor Assembly [17] Power Source 1.0 Linkages [16] After looking at the designs, the team determined that the linkage components for both systems were operating in series. The following equations were used to determine the total reliability. Equation 2 [18] Equation 2 works for the Bolt design; however, it needed to be modified to work for the J-Clamp design. Equation 3 is used for the J-Clamp system. The reason for the modification was to include the six-piece linkage system. With these equations in the team s toolbox, they began the study Series Calculation Results Equation 3 [18] The reliability was a successful way to evaluate both the J-Clamp and Bolt designs. In Table 6, the values of the two system are expressed. Note that the J-Clamp was evaluated upon a system with three and eight clamps versus the Bolt s single linkage system. The rationale behind this is because the J-Clamp system has the freedom to reduce the number of clamps needed to operate. Table 6 shows the three-clamp system has a high reliability for success percentage over the eight-clamp system. This is because the eight-clamp system has five times more moving parts. System Table 6: Reliability Analysis Results Reliability Percentage Bolt 99.7% J-Clamp (3 clamps) 98.0% J-Clamp (8 clamps) 95.1% Down Select Results With these results, it allowed the team to settle on a final design, with confidence, that the team decided on the correct design to begin the next stages of this project. The team s final decision for the separation system that will be moving on to the prototype phase is the Bolt design. The next step in the design is to work out the next iteration of the design that could meet the performance goals of the project. 5.2 Final Design Details After making the decision to move forward with the Bolt system, the team turned its attention 21

22 toward defining the specifications of the design. An analysis was conducted to determine the exact dimensions of the critical parts. Soon after moving forward with the Bolt design, the original concept was altered to address concerns about the energy required to actuate the center threaded part. The diameter of the threaded portion of the mechanism was reduced to decrease the actuation energy by a reduction in friction. This led to the creation of an inner threaded column that acts as a screw to secure the two halves of the system together. The main portions of the design can be seen in Figure The Inner Column Figure 17: Final Design Main Components The inner column is the most important portion of the design. It needs to be strong enough to withstand both the axial and bending loads encountered from both the launch and the other system components. To minimize the energy required to actuate the system, the outer diameter of the column is reduced to 4 inch. This will cut down the weight of the system significantly. Figure 18 shows the critical dimensions determined for the inner column. Figure 18: Critical Dimensions for the Inner Column The axial loads are based upon both the given values from Orbital ATK from the launch and the separation springs within the system [19]. A series of equations (Equation 4-11) were used to find the total axial loads the separation system would have to endure. 22

23 Spring Constant Annotation, Equation, Assumptions, and Solution Equation 4 is used to determine the total length of the spring by multiplying the diameter by π and then multiplying that by how many coils are in the spring [20]. L = π d s C Equation 4 [20] L= Length of spring d s= Diameter of Spring (Assuming a Diameter between 0.2 and 1 in.) C= Number of Coils (Assuming 6 complete turns) Equation 5 is used to estimate a certain spring constant based on a variety of areas, a spring with six coils, and a Modulus of Elasticity of a common high carbon steel at Orbital ATK's preference of 20 C [21]. k = A T L Equation 5 [21] k= Spring Constant A= Area of spring (Assuming a Diameter between 0.2 and 1 in.) T= Modulus of elasticity of spring material (Assuming a Standard High Carbon Steel at 20 C) [22] L= Length of spring Table B3 in Appendix B shows the values that were calculated for the spring constants for different areas. To make things easier for Orbital ATK, the spring constant from the Planetary System was used for the remainder of the calculations Spring Force Annotation, Equation, Assumptions, and Solution Equation 6 is to determine the force the springs will be applying to the payload when compressed [21]. Constant k would be the value calculated in Equation 5, but since this was calculated for multiple areas the k value from the current separation system already on the market (the Mark II Band) was used. The team was told by Orbital ATK to plug in a value for x that came from the existing Mark II Band [23]. F = k x Equation 6 [21] F= Force the Spring will Apply to the Payload k= Spring Constant (used lbf/in based on the Mark II Band Separation Springs have) [23] x= Distance the Spring will Travel (used 0.6 in. based on the Mark II Band Separation Springs) [23] Table B4 in Appendix B shows the values that were calculated for the spring forces Axial Force Annotation, Equation, Assumptions, and Solution Equation 7-9 calculates the maximum axial loads the separation system will see during the entire flight [20]. The sigmat is the maximum axial load the separation system will have to survive when in tension. The sigmac is the maximum load the separation system will have to survive when in compression. Both axial loads take into consideration the forces provided to us by Orbital ATK as well as the forces the springs will have on the system [19]. σ = F = 4 (F G+F s ) A π d2 r Equation 7 [21] σ T = Applied Load + Spring Load Equation 8 23

24 σ C = Applied Load Spring Load Equation 9 σ= Axial Load (T= Tension) (C= Compression) F G= Force Applied to Payload (Value given by Orbital ATK) [19] F s=force Applied to Payload by Separation Springs (Calculated in Equation 3) d r =Minimum Diameter of Collar (3.63 in. based on our design in Figure 2) Table B5 in Appendix B shows the values that were calculated for total axial loads Velocity/Energy Annotation, Equation, Assumptions, and Solution The variable separation force Orbital ATK wants to see from the separation was given to us in units of energy [19]. The energy values were provided and the team converted them to velocity to determine the appropriate separation over time duration our client would like to have. By taking the units of energy in U.S. units (lbf*ft), it was divided by lbf*s to get ft/s [24]. The appropriate equation that the team derived was to take the energy of the springs (EF) and multiply it by 1/(spring constant (k) * distance the spring will travel (x) * the time duration of separation (t)). This will ultimately get us velocity in units of ft/s by using all the necessary variables the springs would have to affect the velocity of the payload separation. Velocity = lbf ft lbf s = E F 1 = ft k x t s Equation 10 E F= Variable Force Energy Required to Launch Payload k= Spring Constant (used lbf/ft based on the Mark II Band Separation Springs have) [23] x= Distance the Spring will Travel (used 0.05 ft. based on the Mark II Band Separation Springs)[23] t= Time wanted to separate (Assuming 20 seconds) E s = K. E. +U. E. = 1 2 m v2 1 2 k x2 Equation 11 [25] E s= Energy of the Spring m=mass of payload (Assuming 15 lb) v=velocity (Calculated in Equation 7) k= Spring Constant (used lbf/ft based on the Mark II Band Separation Springs have) [23] x= Distance the Spring will Travel (used 0.05 ft. based on the Mark II Band Separation Springs)[23] Table B6 and B7 in Appendix B shows the values that were calculated for the velocity conversion and spring energy Moment Annotation, Equation, Assumptions, and Solution A bending moment calculation (Equation 12) was used to determine a wall thickness of 3/16 inch for the inner column [26]. The thickness of the column was determined by using a factor of safety of 3. This was to ensure that deformations of the column during flight would remain small to prevent binding of the threaded portion as well as making this part easier to manufacture. σ = M y I Equation 12 [26] σ = stress due to bending moment (psi) M = moment encountered during ascent (ft-lbs) y = distance from center (in) 24

25 I= area moment of inertia (in^4) After determining the thickness of the column, attention turned towards the threads. One concern from Orbital ATK was having only one starting thread would cause the payload to tip upon separation. To remedy this, 3 starting threads were added to ensure the system separated symmetrically. A pitch of 0.5 threads/inch was chosen to minimize the number of rotations necessary to detach the two halves of the system. 6. Proposed Design The proposed design uses two, inner threaded columns to secure the two halves of the mechanism together. The threaded columns will be secured together using a collar that moves up the two columns to connect them. The collar will be actuated using a cable attached to it and wrapped around, much like the pull starter on a lawnmower. To provide the force necessary to push the payload away from the launch vehicle six springs have been placed around an outer ring to provide a symmetric push to ensure that the payload remains normal to the launch vehicle during separation. In addition to housing the springs, the outer ring will also house alignment pins that serve a dual purpose of withstanding any shear force that the mechanism may encounter during ascent. Like the springs, there are six pins. 6.1 Implementation Plan The team will order materials necessary over winter break (December through January) so that all materials will be in by the time that spring semester starts. A complete bill of materials can be seen in Table 7. For parts that have dashes (--) in their specifications, this information for current systems is proprietary and we are unable to get these values. Table 7: Bill of Materials [14,19] Item Number Part Name Weight (lbs) Dimensions (in) Volume (in^3) Quantity Vendor 1 Fuel Cell Plate Diameter Industrial metal supply company 2 Payload Plate Diameter Industrial metal supply company 3 Threaded Collar Outer Diameter Industrial metal supply company 4 [19] 1/4 in bolts x1 Hex bolt with 0.5 Threads N/A 24 5 [14] Separation Spring (Possible Vendor Orbital ATK) 6 [14] Motor Maxon 25

26 Once back from break, the team will write the CNC code to machine the components of the system. The team will spend February manufacturing our selected design in the fabrication shop on campus. At this time, the only manufacturing that is required is for the machining of the threads. This will be done with the assistance of Orbital ATK. During the month of March, (based off the availability at Orbital ATK) this team plans to test our design at Orbital ATK using a shaker table and other resources from Orbital ATK. If needed, based on the results of our tests, this capstone team will reevaluate the selected design and propose any areas of improvement. Any design modifications will be documented by the second week of April. A complete breakdown of our schedule can be seen in the Gantt chart in Appendix B Figure B Required Resources To produce the final prototype the team will enlist the help of several resources to produce the final prototype. The first resource will be NAU building 98c, the machine shop will provide the tools necessary to machine the top and bottom plate of the mechanism. The production of the threads on the inner column will be outsourced to Orbital ATK, the team is uncertain whether they are capable of machining the threads themselves, as a result they opted to seek the help of Orbital ATK. The team will also seek the help of Dr. Perry Wood and Dr. John Tester for any unforeseen complications that may arise during production of the final prototype. 6.3 Resourcing, Costs, and Budget This capstone was granted a budget of $5,000 from Orbital ATK. Currently, $100 has been used on transportation and $40 has been used on a trial set of Polymagnets. The cost of a subsystem 3D printed by Cline library was $9.40. Our remaining budget is $4, This group has also planned out future expenses. The total cost of materials (purchased from Industrial Metal Supply Company will be $ An additional full-scale prototype that will be 3-d printed is expected to cost $50. The cost of 2 motors is expected to be $100. Additional travel expenses are expected to be $300. A full breakdown can be seen in tables 8 and 9 below. Incurred Expenses Table 8 Incurred Expenses Merchant Amount Reaming Budget Transportation -$ $4, Polymagnets Testing Kit -$30.00 $4,860 3D Printed Subsystem -$9.40 $4,

27 Predicted Expenses Table 9 Expected Expenses Merchant Amount Remaining Budget Future Travel Expenses $ $4, Materials-Industrial Supply Company $ $5, Full Scale Prototype $50.00 $4, Motors $ $3,

28 REFERENCES [1] Company Overview, in Orbital ATK, [Online]. Available: [2] Accessed: Sep. 09, Flight Systems, in Orbital ATK, [Online]. Available: Accessed: Sep. 09, [3] Orbital ATK, Antares Fact Sheet, Orbital ATK, [Online]. Available: Accessed: Sep. 20, [4] Orbital ATK, Antares Mission History, Orbital ATK,2014. [Online]. Available: Accessed: Sep. 18, [5] Orbital ATK, "Antares User s Guide," Orbital ATK, [Online]. Available: Accessed: Sep. 18, [6] Orbital ATK, "Pegasus Fact Sheet," Orbital ATK, [Online]. Available: Accessed: Sep. 10, [7] Orbital ATK, "Pegasus Mission History," [Online]. Available: Accessed: Sep. 10, [8] Orbital ATK, Pegasus User s Guide, Orbital ATK, [Online]. Available: Accessed: Sep. 16, [9] Orbital ATK, "Minotaur VI Fact Sheet," Orbital ATK, [Online]. Available: Accessed: Sep. 14, [10] Orbital ATK, "Minotaur Mission History," Orbital ATK, [Online]. Available: Accessed: Sep. 12, [11] Orbital ATK, Minotaur IV, V, VI User s Guide, Orbital ATK, [Online]. Available: Accessed: Sep. 11, 2016 [12] RUAG, PAS 381S Separation System, RUAG. [Online]. Available: _381S_Separation_System.indd.pdf [13] C. Lazan sky, "Refinement of a Low-Shock Separation System," 41st Aerospace Mechanisms Symposium, pp , May [14] Planetary Systems Corporation. (2014 July 30) MkII MLB User Manual. [Online] URL: [15] NanoRack ISS Workshop. (2015 Feb. 17). Kabar Small Satellite Deployment System. [Online] URL: Deployment-System-Presentation.pdf 28

29 [16] A. Stadtner, EMF and EMR conversion formulas, Healthy Building Science, Healthy Building Science, [Online]. Available: Accessed: Nov. 7, [17] F MkII MLB User Manual, Planetary Systems Corporation, [Online]. Available: Accessed Nov. 15, 2016 [18] B.S. Blanchard and W. J. Fabrycky, Systems Engineering and Analysis. 4e. United States: Prentice-Hall [u.a.], 2005 [19] Steven Hengl, "Separation System Requirements," Orbital ATK, [20] A. S. Website, "Calculate length of coiled spring wire," [Online]. Available: Accessed: Nov. 19, [21] J. E. E. Shigley, Mechanical engineering design: Metric edition, 9th Edition ed. New York: McGraw-Hill Inc.,US, [22] "Young Modulus of elasticity for metals and alloys," in The Engineering Toolbox. [Online]. Available: Accessed: Nov. 19, [23] Planetary Systems Corporation, " F MkII MLB User Manual," [Online]. Available: MLB-User-Manual.pdf. Accessed: Nov. 19, [24] Tom Gaylord, "What is energy?," [Online]. Available: Accessed: Nov. 19, [25] Pearson Education Inc., "Energy in Simple Harmonic Motion," [Online]. Available: Accessed: Nov. 19, [26] F. P. Beer, R. E. Johnston, J. T. DeWolf, and F. Beer, Mechanics of materials, 3rd ed. Boston: McGraw-Hill Inc.,US,

30 Appendix A Figure A1: Bio-Inspired-Riffle Beetle Legs Figure A2: Bio-Inspired-Plant Tendrils Figure A3: Bio-Inspired-Jawless Mouth of Lamprey 30

31 Figure A4: Internal Locking Clamps System 31

32 Figure A6: Rubber Band Contracting System 32

33 Figure A7: J-clamp System 33

34 Figure A8: Polymagnet System 34

35 Figure A9: Wedge System 35

36 Figure A10: Bolt System 36

37 Appendix B Table B1: Pugh Chart 37

38 Torque Test Axial Test Force (lbf) Distance (ft) Torque (lbf-ft) Force (lbf) Table B2: Torque and Axial Test Results Spring Area (A) (in 2 ) Spring Length (L) (in) Spring Constant (k) (lbf/in) Mark II Bank k Value lbf/ft Table B3: Spring Constant Calculations Spring Constant Spring Distance Spring Force (F) (k) (lbf/ft) (x) (ft) (lbf) Table B4: Spring Axial Force (F) (lbs) Min Diameter (dr) (in) σ T σ C Compressed Force Calculations Table B5: Total Axial Load Calculations 38

39

40 Table B6: Velocity Calculations Velocity (ft/s) Table B7: Spring Energy Calculations K.E. P.E. Es

41 Table B8: Gantt Chart 41