P19101: CubeSat Solar Sail
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Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

What did your team plan to do during this phase?

What did your team actually accomplish during this phase?

Our team successfully met all milestones. See the document below for a finalized revised MSDI schedule detailing all tasking and milestones met.

MSDI Schedule RevB

Drawings, Schematics, Flow Charts, Simulations

Electrical System

Selected Electrical Components

NCR18650B Specifications

NCR18650B Specifications

NCR18650B Discharge Temperature

NCR18650B Discharge Temperature

NCR18650B Discharge Rate

NCR18650B Discharge Rate

Sparkfun battery charger

Sparkfun battery charger

Step up voltage regulation module

Step up voltage regulation module

Power Multiplexer

Power Multiplexer

Below is the schematic diagram for connections to be made between the listed breakout boards, as well as motor drivers.

Power System Schematic Diagram

Power System Schematic Diagram

The efficiency of the 5V boost converter at 3.3V input from the battery will be approximately 87% with a current draw of 100-200 mA. This current draw would represent the 5V line at its approximate maximum draw.

Efficiency of 5V Boost Converter

Efficiency of 5V Boost Converter

The 12V line will be used exclusively for driving the deployment motor. The use of this line will be very sparse and will only occur with a fully charger lithium ion battery, which will have a voltage of approximately 4.2 volts. Extrapolating the efficiency data below for a 4.2 volt input, the converter will have an efficiency of approximately 80% at a maximum current draw of 350 mA, which will be sufficient to drive the deployment motor. This efficiency should be considered an acceptable loss, due to the short duration of the deployment of the sail as compared to the length of the mission.

Efficiency of 12V Boost Converter

Efficiency of 12V Boost Converter

Final Mechanical Design

Full Design

Full Design

This image of our full design shows the CubeSat after the solar panels have been deployed, but before the solar sail has been deployed.
Partially Folded Solar Panels

Partially Folded Solar Panels

In this orientation, two of the solar panel flaps have been closed to show volume available for the folded solar sail. Inside the main chassis is where all of the electronics will be housed.

Sail Deployment

The below images show the boom system, made of tape measures, that will deploy the solar sail. The yellow part shows the approximate size of the full booms spooled on the center holder. From there, the center holder will rotate to push the booms outwards. The second picture shows the plate that is in place to protect the geartrain from potential sagging of the booms as they unfurl. The third picture is the worm gear drive that replaced the geneva cam that was put in place by the previous team that had worked on this.
Approximation of Boom Spool Size

Approximation of Boom Spool Size

Half Panels to Protect the Geartrain

Half Panels to Protect the Geartrain

Deployment Geartrain

Deployment Geartrain

Spring Hinge Assembly

Locking Spring Hinge Linkages

Locking Spring Hinge Linkages

Hinge Movement Example

Hinge Movement Example

Stored Hinges in Main Chassis

Stored Hinges in Main Chassis

Solar Panel Hinge Test

Holes for Fishing Line to be Cut by NiCrome Wire

Holes for Fishing Line to be Cut by NiCrome Wire

Holes for Fishing Line to be Cut by NiCrome Wire

Holes for Fishing Line to be Cut by NiCrome Wire

Solar Panel Deployment

Tube for NiCrome Wiring

Tube for NiCrome Wiring

Holes for Fishing Line to be Cut by NiCrome Wire

Holes for Fishing Line to be Cut by NiCrome Wire

Bill of Material (BOM)

The updated Bill of Materials can be seen below. All parts on the BOM have been ordered and will be ready for test and assembly next semester.
Bill of Materials

Bill of Materials

Test Plans

Mass and Center of Gravity

According to cubesat regulations the maximum mass of a 3U cubesat is 4.0kg. According to cubesat regulations the center of gravity must be within 2cm of the geometric center in the x and y direction and within 7cm in the z direction.

Center of Gravity Coordinate System

Center of Gravity Coordinate System

First the mass and the center of gravity will be found in simulation. In the CAD model we have, material properties will need to be applied, then Solidworks will be able to give us the total mass and the center of gravity.

After the cubesat is built we will weigh the cubesat to find the mass. We will also test the center of gravity. To test it we can use a table edge method. This method involves placing the cubesat flat on a table. It is then pushed slowly over the edge in its x,y,or z direction until the cubesat starts to tilt at which point we will make a mark on it. We will repeat this for the x, y, and z direction of the cubesat. Where the 3 tipping points meet is the center of gravity. While doing this we will be careful to not drop the cubesat off the edge of the table.

Vibrations

We will complete vibrations testing to simulate launch conditions. Testing recommended by NASA include random vibrations on each 3 axis and sinusoidal testing on each 3 axis.

We talked to the packaging science department to use their vibrations table but they can only produce up to 300Hz when we need over 1000Hz. Dr. Ghoneim in the Mechanical Engineering Department also has a vibrations table and it can produce larger frequencies in the range we require. We plan to test at 1000Hz.

Thermal

In order to test run conditions in a cold environment, we plan on conducting a thermal test using dry ice. Low earth orbit's temperature varies depends on if you measure the temperature in the sun or in the shade. The average temperature is about 10 degrees Celsius but it can get down to minus 100 degrees Celsius in the shade.

We will put the mostly assembled cubesat in a bin and then pack it with dry ice which reaches -78.5 degrees Celsius. We will then run the electrical components to test if they will work in the extreme temperatures.

It is also a requirement to test it at high temperatures. We will put the cubesat in the oven at 70 degrees Celsius to test high temperatures.

Nichrome Wire Testing

We plan to use Nichrome wire to cut fishing line to release the solar panel flaps. This idea came from a previous senior design team that was creating a cubesat that deployed its solar panels using the same method and can be seen here. They verified that this method will work but we will do some simple tests to confirm it works and see how long it takes to cut the fishing line.

We will also also check to see if it will cut multiple fishing lines stands at once and the time that would take. Multiple fishing lines in tandem would be stronger than one stand of fishing line so if the nichrome can still cut the fishing line in a reasonable time we would probably use multiple lines.

Risk Assessment

An updated risk assessment can be seen below
Updated Risk Assessment

Updated Risk Assessment

Here is a link to the live document.

Design Review Materials

Please select the link below for the detailed design review agenda.

Detailed Design Review Agenda

Plans for next phase

See the document below for our preliminary projected MSDII schedule.

MSDII Schedule Rev-

For senior design two we will build and test our design. The tests above will be completed along with any additional test we feel are necessary next semester. We have already started machining parts and will continue to do that. The parts we have ordered should all be in by next semester for building and assembling.

Adam Stock

Kristin Angel

Jarrett Pischera

Brett Saxe

Nathan Lindberg


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