Unresolved SEP (Systems Engineering Process) Questions
You can see the potential answers here: https://opendesignengine.net/projects/shepard-ts/wiki/Requirements_document
- Q4. What features does it need to have (now)?
- (Jeremy) The issue seems to be with the use of the NAR guidelines. In talking with the chair of the NAR Standards and Testing Committee, it sounds like they themselves follow NFPA 1125. It may be better to focus on that rather than the NAR guidelines. http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=1125
- (G) This standard costs $39.00. Someone (?) needs to purchase this for the Mach 30 organization’s use.
- (Jeremy) Possible answer: Do we want to claim to follow this set of guidance without reading through it first. (G) I’d prefer to read through this standard first.
- (Jeremy) Need to check with the NFPA to understand their distribution and sharing restrictions.
- (G) This is the “Scope” paragraph that was available on the website. This description seems like it is more appropriate for the Test stand work:
1.1.1* This code shall apply to the manufacture of model and high power rocket motors designed, sold, and used for the purpose of propelling recoverable aero models.
1.1.2 This code shall apply to the design, construction, and reliability of model and high power rocket motors and model rocket and high power motor-reloading kits and their components, and to the limitation of propellant mass and power.
1.1.3 This code shall not apply to the sale and use of the following: (1) Model rocket motors (covered by NFPA 1122, Code for Model Rocketry) (2) High power rocket motors (covered by NFPA 1127, Code for High Power Rocketry)
1.1.4* This code shall not apply to the manufacture, transportation, and storage of fireworks.
1.1.5 This code shall not apply to the manufacture, transportation, and storage of rocket motors by the United States military or other agencies or political subdivisions of the United States.
1.1.6 This code shall not apply to the assembly of reloadable model or high power rocket motors by the user.
1.1.7 This code shall not apply to the fabrication of model rocket motors or high power rocket motors by individuals for their personal use.
- (Will) Not clear on the capability and use of the Arduino in terms of the requirements. What is the resolution (both time and data) are we looking for?
(G) At this point, there are not many technical requirements on that side of things. It’s a proof of concept to see if the Arduino can even be used.
(Jeremy) Also the Arduino is “open-source” hardware which is another plus. The use of this system complies to the strategy of Mach 30.
(Will) The industry standard for this kind of application will be FPGAs, with the added complexity that comes with higher performance.
(G) This leads to the budget discussion question.
- Q5. What features does it need to have (later)?
- (Jeremy) Now that I’m looking at it, this question seems to be more of a version 2.0 (and beyond) question. I probably shouldn’t have included it in the version 1.0 questions.
- (Will) Should this follow the Raspberry Pi model (raspberrypi.org). and own the concept of a kit that will be sold through a distributor at a later time.
(G) That model seems to make sense for monitization of selling kits of open hardware
- (...from J’s comments on ODE)
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
- video capture of the tests (high and low speed, from multiple angles)
- integrated ignition systems (so the test management software can control the entire test)
- additional measurements
- higher fidelity measurements
- (G) The idea will be to reference this discussion when we start answering questions for Shepherd 2.0 requirements questions.
- (Will) another benefit with reviewing requirements for future versions (2.0 and beyond) is to document the direction that you want to head, and have an end goal in mind, then you’re in a better position to get there.
- (Will) From a design point of view, we want to AVIOD feature or requirements creep
(Jeremy) To handle this there is a set of requirements that are “gelled” and not “frozen” to allow critical safety errors or design flaw fixes, but not to add cool/nifty features just because.
- Q9. What is the budget?
- (Will) Is there a materials list or a sample parts list?
- (G) This is a top down approach instead of a bottoms-up pricing.
- (Will) Isn’t this a chicken and an egg problem. Don’t we need a parts list to determine a starting point to have a budget? When you put a budget on a project without understanding the problem then there is little value.
- (Jeremy) It has been determined to be arbitrary
- (Will) Is fine with having a low goal. Such that the project is cheap enough to be accessible
- (Jeremy) Don’t we already have the funding for $200 Shepherd Test stand.
- (Will) Does this $200 budget include the “consumables” (like engines) and tools required for assembly? If a router is required, or a laser cutter what is our tool budget?
(G) Lets try and keep the tools limited to the standard garage or hackerspace tool bench. Because these Mach 30 projects are targeted to hackerspace projects
- Make sure to include any required third-party manufacturing if required.
Discussion points on Tools
- (Will) as the tool sophistication increases, so does quality... and the price may go down as a function of quantity scaling.
- (Will) An interesting feature of a low ($200) budget, but a distributed design team is the need for shipping.
(Jeremy) Correct, the concept was to send parts to “Mach 30” for final assembly
or test. Problem there is for the fix of any errors may require shipping back to fix
- (Will) DRC - design rule checks
- (Jeremy) How to capture design changes that were made “on the fly”?
(G) That’s the importance of configuration management, which is one reason that we’re doing this open source using ODE. It easy to get comments feedback about “this is broke!” but the harder part is to get the follow up “I tried this fix and it worked, or didn't work”
(Will) The same concept goes for software.
- (Will) This needs to be broken down more. Break out the questions/comments on tools from ‘h’ onward into its own discussion.
- (Greg) Will specialized tools be needed? This needs to be part of the requirements discussion. Sub-question under design? Something to think about before moving on to other steps.
- Q11. What waste products will be produced by the manufacture and/or operation of this?
- (Jeremy) I’m the only one who’s answered this so far, and there’s been no objection, but I’m not convinced I hit the mark. This came about because of the disposal part of the process
- My original answer - 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.
- Electronics and battery disposal/recycling? Follow federal, state, and local guidelines. (Will) Laptop will power Arduino, and standard launcher may be used, but is there a launcher that will accept TTL inputs?
- Normal storage of test stand frame and disposal of stand if it becomes damaged.
- Easily replaceable parts and proper storage and protection from operation byproducts.
Shepard SEP Questions
- In my view, these questions are designed to help us create a bulleted list of requirements (the questions and their answers themselves aren’t the requirements). Is this the way that everyone else views it? There’s a discussion on the SEP we’re trying to follow here: https://opendesignengine.net/boards/4/topics/8
- General consensus that the Q&A is separate from the bulleted list of requirements.
- (Will) Some aspects of Gantt (planning) need to be addressed.
General Shepard Questions
- Does the $200 budget cover the purchase of Estes engines for testing?
- J Said - Oooo, good question. I don’t think that came up yet in previous discussions. I would sure like some of them to, at least. But motors alone could eat up a small budget like this. We should definitely discuss this one.
- I’ve got an outline done for the Shepard wiki rework. If we have time, maybe we could discuss it. https://opendesignengine.net/projects/sandbox/wiki/Shepard_Wiki_Test_Page
- I’ve also got another document on Shepard procedural questions that I can share if we find we have way too much time on our hands. Many of the questions are probably too broad for this hangout though.
- After the hangout we need to remember to post a link to the meeting minutes to the Shepard wiki.