So my 3d printed version of my 6p pocketqube deployer (need to give it a creative name) had arrived last week.
While I was putting it all together I was making mental notes on how easy it was to put together, how rigid the parts were and areas for improvement. For a first attempt there are areas I want to improve that will make it cheaper to make, easier to assemble and to make it more robust. This is what makes prototyping early in the development phase so valuable as I can make these changes when it’s easy and quickly. Plus I will admit I have mistakes that were difficult to spot in a CAD model but a quick €70 3D printed model has given me the knoweledge to fix these design flaws that would cost me thousands and cause bigger delays.
The design isn’t that far away to be ready for testing but I do need to carry out the functional tests first but it does require some minor changes.
To help record any changes or recommendations for improvement I have created a document that I thought I would share. I hope it can help anyone develop their pocketqubes, cubesats or any product they have in mind.
Here’s a quick run through of the spreadsheet.
Part/Subassembly
Use this to separate each part or subsystem of your satellite. For example, the sections you may be interested in are the solar panels, main structure, electronics, batteries etc. In my case it’s main structure, door, rail and pusher plate.
For my 3D printed prototype, I mainly checked the main structure, rail and pusher plate.
Action
Use this column to explain what you did in your investigation to your satellite.
A couple of examples are:
· Tested the springs on the solar panels
· Assembled the base plate to the satellite
· Tested the burnwire circuit to release the solar panels
In my case one action I carried out was: I assembled the rails to the main structure
Issues and findings
What were the problems faced in the trials?
· Did the solar panel break?, did the solar panel cause the ADCS system to fail?
· Were the holes in the base plate misaligned, did it break when assembled?
· Did the burn wire fail to burn the dyneema wire?
List as many issues you have found when testing the part or subassembly.
Also list the things that went well (don’t always make it negative 😊)
Potential causes
This is mainly for the faults you have found in your design.
List all the potential reasons why things went wrong
You can create a list of these potential causes by carrying out a fishbone analysis (https://www.educational-business-articles.com/fishbone-diagram/)
Root cause
After you carry out a fishbone analysis you will be able to find out what was the reason as to why your part or assembly failed.
· It could have been your spring was way too powerful for the solar panel hinge
· You didn’t properly specify the hole locations or didn’t get them made by a CNC
· The power supply for the burn wire was too low, you used a wire that was too thick, or you used the incorrect resistor, or the circuit is broken somewhere.
Lessons learned
Just like it says on the tin define what you have learned.
· Use the correct torsion spring, add a catch for the solar panel, use a dampener to slow the mechanism down.
· Get the parts made by a trained machinist with a CNC.
· Use the correct supply, use a thinner wire, (insert electrical engineering stuff)
Test
When did you find these issues?
· Was it when you assembled the satellite?
· Was it when you did vibration tests?
Date
When was this test, action?
Continue/Stop/Finalised
I use the final column to define if I need to carry out further work or just stop doing anything to the part or assembly because it’s just not going to succeed or no longer needed.
Finalised means that what ever I did was successful.
Testing Tab
There is also a testing tab which is used to help me track the tests I need to carry out for my deployer prototype.
Test name
What is the test? Is it a vibration test, testing the deployment of the mechanisms?
Main outcome
What do I want from the test? Do I want my deployer to be space qualified? Do I want to prove that my pusher plate will launch satellites?
Items to test
What am I going to need to carry out the test?
I will need 2 dummy 3p satellites to carry out the deployment tests of my pusher plate.
Methodology
How will you carry out the test?
List each step of the experiment.
Equipment
List the equipment you require.
I have attached a blank version of this (https://wyrmengineering.com/lessons-learned-blank-document/) if you want to record your testing and prototyping of your pocketqube satellites. Let me know if you have any ideas to improve this form as I am always looking to improve how I do things.
I have found this document very helpful while I am developing my 6p deployer since I am recording everything I am doing and then investigating the results of the tests. This has led me to modify certain sections of my deployer which will enhance its capabilities and help prevent expensive mistakes. Right now, I am adding the final details to the new design and redo the FEA to see how these changes will affect the overall performance. After that I will get second prototype made which will be milled instead of 3D printed.
Follow me on twitter (@Spaceca27508118) to keep up to date on the developments of my deployer.
wyrmengineering.com 