Build & Test Prep
Table of Contents
Team Vision for Build & Test Prep Phase
- Wired H-bridge to the motor and controlled the direction of the rotation
- Finished final design and drawing changes
- Confirmed with machine shop that design is manufacturable and the tolerances are reasonable.
- Ordered necessary hardware for the frame and for the genva cam
Test Plan Summary
Some test plans from previous phases still need to be completed and are detailed below. These include the sail bonding test, sail folding and unfolding, and sail quadrant compression. In addition to these, new plan drafts were created to test meeting the targets of the engineering specifications. These can be found in this document, along with the engineering specifications and customer requirements they were created to meet.
The combination of individual blankets into the needed sizes to make the solar sails was a key component of our design. If this was not possible, then the sail material with have to be reconsidered and a new material acquired. As such, confirming that the blankets can be bonded into a larger sail was priority for this phase.
- Clean the surface of the blankets or blanket pieces to be bonded.
- Place the edges of the materials to be bonded next to each other on a flat surface.
- Apply the metalized Mylar tape over top of the two pieces, ensuring an even amount on each side.
- Secure both bonded pieces to their respective test surfaces by placing the securing weights on them, making sure the bond is between the fastened areas.
- Ensure that the vertical hang of the bonded sail is at least a foot vertically.
- Gradually add test weights until the bond fails.
- Calculate the force that caused the bond to fail based on the mass of the test weights.
It was originally intended that this be completed by this phase. However, due to shipping and handling time associated with acquiring the metalized Mylar tape, this could not be done. Instead a very rough test was done to get a ballpark estimate if the metalized Mylar tape would work, which it was determined it would by a large margin. This test will be carried out by Eric and Mike.
Sail Folding and Unfolding
The folding of the sail material needed to be done to determine three main things: the volume of space taken up by the folded sail, the ease of sail deployment by the boom extension process, and the possibility of damaging the sail material during the process. This test would then determine if additional risk mitigation techniques would be needed for the risks associated with this process and to determine what folding method was the best. This test requires two people.
- Clean the test surface.
- Lay the unfolded sail flat on the test surface.
- Fold the sail into the compacted shape.
- Calculate the volume taken up by the packaged sail.
- Determine a value on a scale between 1 and 10 of the likelihood and severity of sail tears during the folding process (1 being the lowest and 10 being the highest).
- Attach the folded sail to two booms for testing. The attachment method used can be zip ties or string through eyelets in the boom and sail corners.
- Have one person hold down the corner of the sail that would be attached to the CubeSat frame.
- The other person slowly and evenly extends the booms to unfold the sail.
- Determine a value on a scale between 1 and 10 of the likelihood and severity of sail tears during the unfolding process (1 being the lowest and 10 being the highest).
- If the folding pattern unfolds completely without damaging the sail, the pattern will be considered. Otherwise discard the folding pattern.
This was also intended to be completed by this point, but again shipping and handling time of the metalized Mylar tape prevented this from being tested on larger sail pieces. For this phase, we were able to test the four small sails used in the demo model and full blankets, but mainly the feasibility of the patterns was tested and the likelihood of tears from folding and unfolding was not quantified according to the scale. Mike and Eric will conduct this testing, but it will likely be unnecessary based on the small-scale results. This is because of the pre-existing fold lines, which as detailed in the sail folding feasibility, make following the existing pattern used to package the blankets for shipping the most effective option.
Sail Quadrant Compression
The prototyping of the sail quadrant creation revealed that the folded quadrant's volume depends on the amount of compression force on it. This was not surprising, but the force required to keep it within an acceptable volume must be calculated to determine the needed strength of the sail storage area and components to hold the sail in place until deployment.
- Remove the restraint on the folded blanket while making sure it does not unfold.
- Determine the mass of the top flat plate.
- Place the folded blanket between two flat plate objects.
- Place the plates and sail on the flat test surface.
- Using a caliper, measure the height of the folded sail.
- Determine the mass of the test mass.
- Place the test mass on the top plate.
- Measure the height of the folded sail using the caliper.
- Repeat steps 5-7 until the compressed sail height is within the acceptable range.
- Determine the force exerted by the test mass and top plate on the sail in the acceptable range.
This will be completed this phase in order to determine the amount of force needed to keep the sail quadrants in place. This will then be used to design the sail storage area and the components holding the sail in place until deployment. Eric and Mike will complete this test.
Risk and Problem Tracking
The problem tracking document has been setup so issues that come up can be addressed in an organized manner. So far this phase, no new issues have come up for tracking. As issues come up, they will be added to the document and potential solutions and the selection and execution of the chosen solution will be tracked as well. The document is located here.
Plans for next phase
We plan to accomplish the following tasks:
- Assemble and test the Geneva cam and motor
- Assemble the frame created my SPEX
- Build the four quadrants of the sail
- Paint the measuring tapes
- Begin the vibration simulations
- Solder the H- bridge to the protoboard