P18101: CubeSat Solar Sail
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Subsystem Build & Test

Table of Contents

Team Vision for Subsystem Level Build & Test Phase

Tasks Accomplished:

Received and Assembled Frame Components

Two versions of the machined components were received: a machined version with rough tolerances and some design specifications missing for use in prototyping and a second water jet cut set. This second version had all of the required design components that the machined version lacked and much tighter tolerances. Some of the components were still undergoing revisioning and as such were 3D-printed for use in testing and assembly. These machined components and their integration with 3D-printed components can be seen below.
Rough Machined Frame Components

Rough Machined Frame Components

Vertical Rails

Vertical Rails

Set of Final Machined Components

Set of Final Machined Components

Machined Geneva Cam Components on 3D Printed Test Plate

Machined Geneva Cam Components on 3D Printed Test Plate

Cam Components Next to a Caliper

Cam Components Next to a Caliper

Wire Location in the Deployment Mechanism

Wire Location in the Deployment Mechanism

Internal Frame Components

Internal Frame Components

Assembled Frame with Sales

Assembled Frame with Sales

Test Results Summary

Results Summary

The Test Plans and their results can be viewed in detail here.

Risk and Problem Tracking

Risk Assessment

Risk Assessment

Risk Assessment

Problem Tracking

Sail Quadrants

It was discovered in a previous phase that our original target of 32 square meters for the deployed sail was too ambitious given our timeline and budget. This was because in order to fit a larger solar sail, a thinner, much more expensive material would have had to be ordered. As a result, this phase a goal was to complete the four quadrants of a 16 square meter sail. There were several issues that came up with the construction of these quadrants which were overcome. As mentioned in previous phases, the metalized mylar blankets the sail is being constructed from do not have straight edges which could be incorporated into the sail edges. To resolve this, the edges of each blanket had to be trimmed, reducing the size of each sail. This caused the dimensions of each blanket to change, which necessitated unique calculations of the size of the components for each sail quadrant. This was taken into consideration, but as we progressed other issues became apparent. One of these was issues with individual blankets having an incorrectly sized fold. This created an issue when folding, making the packing efficiency lower and increasing the volume of the folded sail. To address this, blankets with this problem were used to make the small corner segments where this would not impact the folding as much in future quadrants. Another issue was with the taping of the sail components. In the first two sail quadrants there were places where the metalized mylar tape was placed over a fold line. This made the packing efficiency lower and resulted in the sail taking up additional volume. This was addressed in the final two sails by cutting the sail material so the tape would not be located on a fold line.
Cutting a Sail Component From a Blanket

Cutting a Sail Component From a Blanket

A Completed Quadrant for the 16 Square Meter Sail

A Completed Quadrant for the 16 Square Meter Sail

A Completed Quadrant for the 16 Square Meter Sail

A Completed Quadrant for the 16 Square Meter Sail

Sensors

The sensors were tested against a base case of the same sensor that functioned properly. However, the purchased sensors did not work originally. The output of the sensors, which should have been a 0 or 1, was always a 0 and would not change values. Originally, this was assumed to be an error in the soldering of the sensors, but after extensive testing and consulting subject matter experts, it was determined that this was not the case. The next solution attempted was to purchase new sensors and test those in case we had received a defective batch. However, after testing the new sensors they did not work either. The supplier was then contacted to discuss the issues with the sensors. Throughout this dialog, it was revealed that the sensors, while nominally identical to the base test we were testing against, would not function using the same code. Although the supplier could not provide a reason for this, they were able to guide us into the proper way of coding them. Using this information, we were able to successfully use the sensors.

Motor Torque

Originally the motor and geneva cam assembly functioned properly with the motor able to easily turn the cam and attached to the spindle. However, once the booms were attached to the spindle, the motor no longer had enough torque to turn the spindle. The additional force required to turn the spindle with the booms was too much when the pin rotating the cam moved to the point closet to the center of the cam where the required torque was the highest. Two possible solutions to this issue were considered; purchasing a new motor and designing a cam with more, less deep slots. After consideration, a new motor was purchased that can provide 3 times as much torque with the same physical dimensions so no other design changes will be necessary.

Painted Booms

The painting of the boom markings to track the boom deployment and retraction was originally done with 1" increments. To make this as simple as possible, 1" wide masking tape was purchased to cover the increments that were to remain unpainted. However, the tape was actually 15/16 inches, and to maintain the 1" increments two pieces of tape had to be overlapped. When this was painted with the spray paint and the tape was removed, it was found that paint had leaked underneath the edges where the tape was overlapped and had created a small gap. In addition, the amount of paint applied was too high, causing additional leakage and bleeding through the tape in some locations. To correct this, painting was done with a much thinner coat and only a single piece of tape with the increments being 15/16 inches on the taped sections and 17/16 inches on the untaped ones. This does not cause an issue with the deployment code.

These processes can be seen in the problem tracking document here.

Engineers Week Celebration Presentation

On Wednesday, February 21st, 2018, Andrew traveled to the Ridley Park Boeing Facility in Philadelphia as part of a larger team of MSD personnel to represent the group for the site’s Engineers Week Celebration. After leaving via the Rochester airport at 6 AM, a display consisting of the most current prototype and a descriptive poster was set up in Boeing’s cafeteria for the event. From 10 AM to 1 PM, Andrew presented the display to passing-by Boeing employees, university students, and high schoolers, along with videos of the geneva cam functionality and the initial small-scale prototype constructed last semester. Following the main event, the group toured Boeing’s V-22 Osprey production line and met with a number of Boeing employees who were RIT alumni to learn more about the company and the professional operating environment. The poster, which can be found to the right, focused primarily on conveying the core aspects of the design’s functionality, utilizing visuals as a primary means of expressing ideas (The thumbnail can be clicked to view the full size image).

Functional Demo Materials

Plans for next phase


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