Shepard Test Stand Initial Questions v1.0

This document has been relinked to the Initial Questions document here as part of our versioning system update.

Below is a list of questions and proposed answers to help us narrow down the requirements for this project. You can view the original forum discussion here

Q1. Why are we making this?

A1. The Shepard Test Stand is the first step toward developing an open source test stand for flight capable rocket engines. It's focus on low power, commercially available amateur rocket motors is intended to provide a safe first experience for both designers (low power and low cost lead to little penalty for failing to meet design goals the first time around) and operators (low power leads to lower cost if accidentally misused during early training). Additionally, as one of Mach 30's earliest open source hardware projects, it will give us practical experience in open source hardware development and managing projects on ODE. Finally, we have received interest in performing live demonstrations of the test stand as part of educational and outreach activities, so it is expected the test stand will become an educational and marketing tool.

Q2. Who is this for?

A2. The Shepard Test Stand is for anyone wanting to learn about measuring the performance of rocket motors. This includes open source spaceflight designers who will design and build future test stands (at Mach 30 or elsewhere), Mach 30 operators who will use future test stands in other Mach 30 projects, students and educators who want to bring rocket engineering into the classroom, and anyone else interested in how rockets are tested.

Q3. How will this be used?

A3. The final test stand will be used for verification of typical motor performance metrics such as thrust and exhaust temperature. These metrics will be compared against benchmark values provided in the Estes motor documentation . The test stand will also be used to do demonstrations at various conferences and educational events (outdoor only).

Q4. What features does it need to have (now)?

A4. The test stand needs to:
  • Be easily set up and torn down for demonstration purposes.
  • Be easy to package for shipment to any event at which it will be used.
  • Provide a stable base on which to test model rocket motors.
  • Accommodate Estes rocket motor sizes A through E.
  • Provide the ability to measure thrust and exhaust temperature while keeping an accurate timestamp for each data point.
  • Conform to the Shepard Test Stand safety requirements, which are based on the NAR Standards & Testing Committee Motor Testing Manual Version 1.5 .

Q5. What features does it need to have (later)?

A5a. Version 2.0
  • High and low speed video capture of the tests from multiple angles.
  • Integrated ignition system so the test management software can control the entire test.
  • Additional measurements.
  • Higher resolution measurements.
A5b. Beyond Version 2.0
  • High power commercial solid motors.
  • Small hybrid motors (on the thrust scale of high power commercial solid motors).
  • Larger thrust hybrid motors.
  • Small liquid engines.
  • Medium liquid engines.
  • Large liquid engines.

Q6. What are the legacy requirements?

A6. This is the first project of its kind at Mach 30, there are no existing projects it must interface with. However, if the system includes desktop control software, that software should run on all three major PC platforms (MS Windows, Mac OS X, and Linux). Additionally, it should use standard connections back to the control software (for example, USB, Ethernet, or similar connections).

Q7. Who's going to build this?

A7. It is assumed that volunteers within the Mach 30 community will build this test stand. The designs will be open so that ANYONE, without necessarily a technical education in rocketry, propulsion, or engineering, would be able to build and operate a Shepard test stand.

Q8. How many do we want to make?

A8. One (for now). If the design proves particularly valuable as a teaching or training tool, we may revisit this decision. If highly successful, it is not outside the realm of possibility to consider offering it (or a related design) as a kit for others to assemble.

Q9. What is the budget?

A9. $200, firm. If there is a conflict between function and budget, for this iteration, budget should trump. Our goal is not to make the perfect test stand, it is to make the first prototype of a test stand and see what we can learn from that experience (both about test stands, and about our processes). We can always go back and do another iteration to meet the design requirements if needed. Holding to a firm budget minimizes the amount of time spent trying to make it perfect (once you are out of money, you have to wrap up the project, successful or not). Even a "unsuccessful" prototype will teach us important lessons to apply moving forward. This budget does not include "consumables" such as motors, nor tools, but the $200 cost for the stand itself keeps the basic project affordable if standard tools found in hackerspaces can be used. Any manufacturing that has to be hired out to a third party will be taken out of the $200 budget, and should be avoided to keep this project more practical for those same hackerspaces.

Q10. What is the timeline?

A10. The goal is to complete the project within three months of formal launch as an exercise of agile design. However, given the project is also an experiment in open source hardware development and is all volunteer based, we need to recognize the need to be flexible in this requirement.

Q11. What waste products will be produced by the manufacture and/or operation of this?

A11. Spent Estes motors will be a waste product of the operation of this test stand, and any residual materials should be treated as hazardous. Disposal of these motors should conform to all local, state, and federal guidelines. Estes motors are based on black powder propellant, so any motors that do not fire properly or are damaged can be disposed of in an ordinary manner by first soaking them in water until the casing unwraps and the propellant falls apart. Possible electronic waste items may include batteries from the ignition control box, and circuit boards. These must also be disposed of according to all local, state, and federal guidelines. If the frame of the test stand is damaged beyond repair during operation, proper disposal/recycling guidelines must be followed for the materials used in its construction.

Gelled: 2012-05-03 v7

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