Wyo Galactic Final Report

Conceptual Design Review | 1

WYO GALACTIC 2009-2010 /
Wyo Galactic Final Report /
Final Draft /
Charles Galey;Nicholas Roder;Peter J. Jay;William Ryan /
4/29/2010 /

Abstract

Colorado Space Grant Consortium (COSGC) and NASA offer Universities in the United States affordable access to sub-orbital space flights. Wyo Galactic, composed of four Mechanical Engineering students, will continue UW involvement for a second year. The goal of Wyo Galactic was to develop technologies and components for future UW experimenters to use as part of their test packages. These experiment sub-systems included, a rotationally stabilized camera plate, GPS tracking and logging of flight data, wireless recovery of test data.

Final Design Report | 1

Table of Contents

1. INTRODUCTION

BACKGROUND

PROJECT DESCRIPTION

Overview

Goals

II.DESIGN

ENGINEERING SPECIFICATIONS

Terrier-Improved Orion Rocket

Stabilized Plate

Instrumentation / Experiments

Wireless Data Transmission

MORPHOLOGY

GPS Tracking

Substructure

Power System

Batteries

Plate Stabilization

Plate Assembly

Instrumentation and Experiments

Camera

Accelerometers

Wireless Transmission

FINAL DESIGN

Structural Support

Drive Train

Command and Control

Main Board

Camera Control System

Sensors

Power

BROADER SOCIATAL IMPACT

III. FABRICATION

Substructure

Standoffs

Support Platters/Experiment Platters/Rotating Plate

Support/Power Transmission Shaft

IV.TESTING

TESTING

V.MANAGEMENT

BUDGET

SCHEDULE

COLLABORATION AND LOGISTICS

VI. CONCLUSION

VII. APPENDICIES

Appendix A: Detailed GPS Morphology

Appendix B: Power Generation System

Appendix C: Detailed Instrumentation Morphology

Atmospheric Science

Composite Materials

Relativity

Crystal Oscillator

Biological Experimentation

Appendix D: Detailed Wireless Transmission Morphology

Satellite Modem

Infrared (IrDA)

Other Wireless Methods

Appendix E: Full Electrical Schematics

Main Board

Camera

Accelerometer

Power

Appendix F: Technical Drawings

Appendix G: Flow Chart and Process Diagram

Appendix H: Budget

Budget for Senior Design Salaries

Parts List

Final Design Report | 1

1. Introduction

BACKGROUND

The purpose of the RockSat program is to provide a low cost means for student and university access to space. RockSat rocket and payload requirements were designed specifically to make this process as straightforward andsimple as possible. The inaugural year of the RockSat program was 2008. Students from universities across the country designed payloads that were launched June 26, 2009. A Terrier Improved-Orion rocket catapulted four RockSat customer canisters with 10 experiments from Wallops Flight Facility (WFF) to an altitude of over 75 miles.

In ’08-‘09, two teams from the University of Wyoming successfully designed, built, and flew two experiments. The projects were designed in conjunction with the University of Minnesota, who shared a canister with UW. Experiments flown by UW included testing effects of extreme G-forces upon crystal oscillators (in excess of 20 G), a multi-sensor package including: temperature, humidity, and an extensive processing and data storage system for payloads. This system was developed by the Electrical Engineering team members and contains an open ended operating system, which was designed to be easy to use, and offer a streamlined approach to integrating a variety of experiments.

Great importance was placed on developing systems which may be used for future projects. This would enable future design teams to place more of an emphasis on developing actual experiments as all of the acceleration recording, power, processing, and data storage systems will have already been developed. All of these systems are essential for any successful experiment. With this in mind Wyo Galactic developed a payload that would provide a solid, easy to integrate base to future group projects.

Wyo Galactic was committed to creating flexible, task oriented, and advanced payload subsystems for future teams who require high quality products for their forward-thinking applications. We accomplished this by: Creating a payload providing a stabilized platform which will be utilized to deliver images for analysis by University of Wyoming and the new University of Minnesota team (MinnSpec); Tracking the flight of the rocket using a GPS module; Wirelessly retrieving payload data post flight before obtaining the physical payload; While ensuring all systems are easy to use, understand and integrate into any future payload system or application.

PROJECT DESCRIPTION

Overview

UW RockSat team, Wyo Galactic, designed, built, and will test a rocket payload for the NASA RockSat Program. NASA requires that the payload fit inside the NASA designed RockSat canister. Wyo Galactic will split the canister with a University of Minnesota based payload group, MinnSpec. RockSat canisters must meet stringent requirements to be qualified for launch in June 2010. NASA’s criteria are discussed below in the Engineering Specification section. The first goal of the group was therefore, to design a payload that will meet or exceed each of these requirements. To achieve this goal Wyo Galactic designed a robust package that also met several experimental objectives. The payload will address 6 major areas of interest identified by the design group:

• Experimental Instrumentation
• GPS Tracking
• Data Storage/Processing
• Data Transmission
• Rotationally Stable Platform
• High Quality Photography

Goals

There were several goals that Wyo Galactic set in addition to the completion of each system. The payload was to properly integrate with the experiment developed by UW partner group MinnSpec. Experiment needed to meet COSGC and NASA provided deadline requirements. The payload was selectedfor flight on the June 24thlaunch date, and must survive the flight, and provide retrievable data. UW also hopes to analyze the data before returning home from WFF.

ENGINEERING SPECIFICATIONS

Terrier-Improved Orion Rocket

The RockSat payload canister has specific dimensions, weight, center of gravity and ports. The summary of key constraints can be viewed in Table 1 as seen below. An important consideration when viewing the constraints is Wyo Galactic’s fraction of original values (half) due to sharing a canister with MinnSpec.

Table 1: Summary of Key Constraints

Type / Quantitative Constraint
Physical Envelope / Cylindrical:
Diameter: 9.3 inches
Height: 4.75 inches
Mass / UW Payload = 6.5 lbm
Canister + Payloads = 20 ± 0.2 lbm
Center of Gravity / Lies within a 1x1x1 inch envelope of the RockSat payload canister’s geometric centroid.
Ports / Customer shall provide drop down tubing for atmospheric plumbing. Plumbing must terminate with a male ¼” NPT connector. Additionally, the customer shall design in a redundant valve to protect the payload at splash down.

(Source: RockSat Payload Canister User’s Guide 2010)

Electrical specifications for the rocket payload include the payload access window and wire-way, optical and atmospheric ports, power, telemetry tracking and control, finally harassing and stacking. The window alongside the canister has dimensions of 3.5 inches wide by 4.5 inches tall, and MinnSpec has agreed to give Wyo Galactic access to the whole window. Each payload must be completely self-contained with a hookup for an early activation relay so that Wallops has complete control of payload current at all times. It is highly recommended that experiments have rechargeable batteries, but the use of rechargeable lithium ion batteries is prohibited.

All data must be stored on internal memory as experiments will not be allowed to transmit data while the rocket is in flight. All payloads shall harness wires with a nylon lacing tape or the equivalent. It is also recommended that all connectors and IC sockets be tied and staked in place using aerospace grade RTV.

Table 2: Key Performance Parameters

Key Performance Parameter / Value
Altitude (km) / ≈115 km
Spin Rate (Hz) / ≈1.3 Hz at Terrier burn out;
≈4.8 Hz at Orion burn out
Maximum Ascent G-Load / 25 G
Rocket Sequence (Burn Timing) / 5.2 s Terrier burn—9.8 s
coast—25.4 s Orion burn
Chute Deploy (seconds) / 489.2 s
Splash Down (seconds) / 933 s

(Source: RockSat Payload Canister User’s Guide 2010)

Wyo Galactic’s canister will undergo tests to verify its ability to withstand G-load requirements (Table 2). As one of the biggest environmental conditions to account for is the G-load the payload will undergo. During the flight the specifications the payload has to be able to withstand 25 G’s of quasi-static loading thrust axis, a possible 35 G impulse in along the thrust axis and 10 G’s in horizontal axes. The payload must pass three vibrations tests, centroid verification and two Day in the Life (DITL) tests before it will be cleared for launch.

Stabilized Plate

A plate will be spun via electric stepper motor which must have the capability to spin the platform at a maximum rotation of 288 rpm (to match the rocket’s maximum spin rate). The motor must also have enough torque to accelerate the plate and experiments at the maximum spin rotation acceleration of the rocket, which is not yet known.

The plate itself must withstand the gravitational forces (35 G’s max) created by the rocket on both the plate and the attached cameras. To support the plate a shaft has been designed which will withstand all torsion forces created by the motor and rocket. A bending force will also be placed on the shaft when the rocket becomes parallel to the surface of the earth, and when any centrifugal forces are places on the assembly. This shaft will be supported by a steel ball bearings which must withstand all forces, both axial and radial created by the system.

Instrumentation / Experiments

Accelerometers are the only analogdevices that will be flown. Two accelerometers will be used to measure both the spin rate and lateral movement of the rocket. Along the rocket thrust axis, a single axis accelerometer should be able to measure up to 35 G’s and surface mount for easy integration. To measure rotational accelerations requires a single axis accelerometer capable of less than 2 G’s. The third accelerometer needs to be dual-axis with a measuring capability greater than 10 G’s.

Wireless Data Transmission

The wireless system must transmit the stored data within a reasonable time frame and distance. Representatives of the COSGC have advised that there will be access to the rocket as it is returned to WFF. We should be able to get within 50 ft. of the rocket. Therefore, the range of the wireless system does not need to be too large. It has been determined that there will be 5.5MB of data to retrieve (see Table 5 on page15). The wireless connection will provide a transfer rate of at least 250kb/s at a range of 100ft.

1. Design

MORPHOLOGY

In previous versions of the design this morphology took the reader from inception to selection of parts. Since then Wyo Galactic’s design evolved to reflect the practicalities and requirements of real world design. This section will discuss the original parts from last semester and how they have evolved to Wyo Galactic’s final design.

GPS Tracking

The first GPS unit that was selectedfrom the 8 design specifications stated in Appendix A. That device was the Copernicus DIP Module from sparkfun.com. This particular GPS model has a cold startup time of 39 seconds which was longer than desired. The update rate for this particular model was 1Hz and includes an onboard RAM memory. The cost of this specific GPS module was $74.95 excluding shipping and handling.

However, shortly before our ordering process began the Copernicus became out of stock and backorders were not allowed. As a result a new module had to be selected as close to the previous spec’s as possible.The new selection was called the Micro-Mini which meets and exceeds the capabilities of the Copernicus. The cost of the new GPS module was $79.95 excluding shipping and handling. The refresh rate is the same (1 Hz) with an SMA Antenna port. Additional benefits included much faster start times and a smaller form factor.

Substructure

For the most part Wyo Galactic utilized the substructure which was designed last year. Some changes were made, such as material, mounting holes and other modifications to accommodate the stabilized plate. Further modifications are detailed in lower sections.

The substructure will be tested for structural soundness via calculations and through utilization of finite element programs.

Power System

Several options were considered for powering the payload from batteries to nuclear fusion. While fusion would have been a good option lack of ability to enrich uranium was a significant drawback. A power generation system was planned the full morphology of which can be found in Appendix B. The generation system has been discarded so, experiments will be powered by a system which will consist of standard batteries.

Batteries

Originally, Wyo Galactic wanted to utilize the high efficiency of lithium-ion batteries; however, the use of these batteries is strictly prohibited by NASA. This has led to choosing standard alkaline batteries. There are many benefits to using these batteries including cost, ease of use, and can be purchased at virtually any store. These batteries are very reliable; they do not have a chance of exploding after prolonged use, and will be able to sustain our power needs under the flight constraints. The batteries must have enough capacity to power the wireless transmission several hours after launch.

Plate Stabilization

Plate Assembly

After determining that the power system would not function as intended the group chose to build a system which would provide a stabilized mounting platform for future experiments. This system entails a plate mounted to a freely spinning shaft. The shaft is supported by two bearings which provide support in both radial and thrust directions. The shaft and plate are spun by a stepper motor which is controlled by the main CPU. The CPU takes inputs from the accelerometer packages and spins the motor and therefore the plate at a rate and direction to counter act any spinning done by the rocket. A mockup assembly can be seen in Figure 4.

Figure 4: Stabilized Plate Mockup

Motor– A JAMECO 237490 NEMA 17 stepper motor was selected to drive the camera plate. Using the masses, geometries of the camera plate and the components mounted on it was determined that the motor would need to provide 7.2 oz-in of torque. The motor selected will provide 25 oz-in at 5 volts and is capable of the precise speed control needed for the plate to remain still relative to the rocket. The motor can easily travel at 288 rpm and provides enough torque to properly accelerate our plate and experiment.

Shaft – The shaft for this system must withstand two major forces;

1. The forces exerted by the plate and experiment under a maximum G load of 25 G’s.

2. The forces created by tension in the belt and the components under the tangential acceleration of the spinning plate. This component was made of mild carbon steel.

Plate– The plate must withstand all torsion forces created by the mass moment of inertia of the experiment & plate, and the torque created by the motor. The plate must support our experiment and the weight of the plate under maximum G loads of 25 G’s. These components will be made of Aluminum.

Bearings- The bearings must withstand both radial and thrust forces for this experiment. Radial forces will include the forces created by the rocket during flight, and the forces created by the motor, connecting belts, and pulleys. Instrument ball bearings will be used.

Platters- Substructure platters must be modified to incorporate this system. This will include changing the spacing of the platters to accommodate for the plate, experiment, and stepper motor. In addition to this holes will be drilled in the platters to accommodate bearings, and serve as motor mounts.

Instrumentation and Experiments

Full details of each experiment that was rejected (not included in the final payload) due to feasibility and other reasons can be found in Appendix C.

Camera

The plan at the end of last semester was to purchase a camera from a big box store and disassemble it until only the circuitry and other necessary components were left. After several cameras failed to meet requirements an alternative was found from the security community. The DVR623V 5M DSC/DV module is simply a barebones circuit board with a bonus, a detached lens allowing significant changes to the plate and space requirements. Where the old plan required the circuit board with lens attached to stand tall at almost 4 inches the new lens allowed a height of less than 2 in. Decreased weight on the edge of the plate and associated geometry changes reduced torque requirements from 23 oz-in to less than 8 oz-in.

Accelerometers

Wyo Galactic was originally planning to have two accelerometers, determining the acceleration and spin of the rocket. The accelerometer that was designed for was a 3-Axis VTI: SCA3000-E05 from digikey.com. Further design this semester revealed that this accelerometer would not measure high enough g-forces in a single plane. Thus the sensor package was redesigned with a single axis accelerometer measuring up to 35 G’s recording in the thrust direction. Two additional 2-axis accelerometers placed at the edge of the payload with resolutions of up to 18 G’s will record rotational and horizontal G-forces.