Mini Sparrow

Materials: Tools/software:

• Plans - Laser Cutter
• Glue sticks - Marker
• Foam board - Razor blade
• Tape - Hot glue gun
• Wooden skewers - Right angle/gauge for dihedral angle
• Rubber bands - Inkscape
• Clay - Corel Draw

Workflow:

The second plane we made was called the Mini Sparrow. On the FliteTest website, they provide a video tutorial and plans. We used the same foam building techniques that we used to build our first chuck glider, but this time we had to cut out our own plans. Using the laser cutter, we cut our pieces from the foam board and experimented with a new laser cutting technique, color mapping. The PDF of the original plans as well as a PDF and CDF of the altered plans can be found in the "Mini Sparrow" google drive folder above.

To prepare the document for laser cutting in Inkscape:

1. Download the pdf of the plans from the FliteTest to your computer
2. Open Inkscape and import the pdf (There are two pages with necessary parts for the build that you must import one at a time)
3. Ungroup all objects

1. Calculate the number in which you must scale all the parts. For example. the measurement for mine read 9.01in and the wing should be 28.5in, so I need to scale everything by 316.315% (28.5/9.01= 3.16315)
2. Before you scale everything, it might be easier to delete any excess logos, part numbers, etc. that you don't need.
3. Select all objects and click object -> transform -> scale and enter % value

1. Arrange the parts so that they fit on one page (30in x 20in).
2. **Decide which color will represent each cut (marker, 50% score, or all the way through). On my plans: blue=all the way through red=50% score green=marker
3. Save Inkscape file as SVG or PDF.
4. Import SVG/PDF into Corel Draw, unlock all objects, ungroup all objects, and change all line thickness to "hairline".
5. Follow the "Fusion Laser Cutter Color Mapping Workflow" (in the google drive folder) for setting preferences and printing.

**There are a couple of things besides the colors that we changed in order to make the laser cutter cut it out faster:

1) Make any dotted lines solid (use 11th or 12th icon down on the left-hand side to draw in a new line)

2) Make any dotted curves solid (click on 2nd icon down on the left-hand side -> select two segments you want to connect by holding down the shift key -> continue holding down shift key and select end nodes (should turn blue) -> click on 5th icon at the top)

3) Delete any unnecessary shading (you can always refer back to the original plans when building plane)

4) Simplify curves by getting rid of excess nodes (click on 2nd icon down -> click on the line/curve -> path -> simplify).

Color mapping:

• If you color code the plans on Inkscape/Corel Draw, when you set up to print on the laser cutter, you can check the color mapping box. This will allow you to change the speed and power in which the laser cutter cuts those specific colored lines (*make sure you use the exact same color on all of the lines that you set on color mapping). It is also crucial to set the lines on Corel Draw to hairline before you print in order for color mapping to work.

Above is a photo of what your screen will look like when you open up print settings, under the color mapping tab.

1) Check the box "Color Mapping"

2) Select the same color(s) as used in the file (do this by moving the R, G, and B sliders)

3) For each color, decide how much you want to cut through and change the speed and power accordingly.

We kept the frequency at 10, but for blue lines (all the way through) speed = 20 and power = 100, red lines (1/2 cut) speed = 50 and power = 50, and green lines (marking) speed = 50 and power = 20.

4) Check the box "Vector" only

5) To apply changes, click the "+"

What we did differently from the video:

The Mini Sparrow and the Chuck Glider were similar in many aspects and some steps in building them were exactly the same. Therefore, some of the more complicated steps were easier to complete since it wasn't my first time doing them. For instance, using the gauge to make the dihedral/polyhedral angle in the wing and building the fuselage were easier the second time around. The video explains how to add control surfaces, but we did not get into that. Aside from altering the plans in Inkscape, we didn't change much else. However, we learned a different technique to bevel cut an edge in the Mini Sparrow tutorial. For the Chuck Glider, we used a bevel tool (and FliteTest used a razor blade). For the Mini Sparrow, we used a marker to press down the middle, which had the same effect as cutting it out.

Flight Results:

Our flight times were quite disappointing with 3.3 seconds as our highest. On the second trial, our plane flew for 1.9 seconds and on the third trial, our plane flew for 1.5 seconds. Below are videos of our first and second trials. There is definitely work to do to improve on our time.

Issues/Challenges:

It seems like we had the same issue as last time with the amount of weight we placed in the nose before flying. Clay is put in the nose of the plane so that the center of gravity is in the right spot. Looking back on both of the videos, it appears that there was too much weight in the nose because both times the plane descended immediately. The other part of the problem, I think, was how we were throwing our plane. Throwing it a bit harder, like adding throttle, might have helped it fly longer.

We didn't have many problems in the building process. Because we had already built the Chuck Glider, we were familiar with the process of putting the parts together. Most of the challenges came in the beginning when we were altering the plans in Inkscape. In order to change dotted lines to solid lines but keep everything in the same position required us to get creative. I found the easiest way to replace a dotted line with a solid line was to draw a straight line across the dashes, select the line, use the arrow keys to move it up 10 spaces to make room to delete the dashes, and then move it back down 10 spaces. Other tools, such as joining endnodes and scaling, took trial and error to figure out. Lastly, because color mapping was a new laser cutting technique, it was difficult in the beginning, but now that I know how to use it, it will be very helpful for future projects.

Conclusion:

The second round of building planes using the same foam board technique as the first time was definitely easier because I felt like I knew what I was doing and could do everything a little bit faster. The added difficulty came from changing the plans on Inkscape in order to cut them out on the laser cutter more efficiently. We had to use tools on Inkscape that we had never used before, but in the end, I think I learned more than if I were just given instructions on exactly how to do it. Also, laser cutting our own plans onto foam board gave me more experience with Corel Draw. This concludes the aviation section of the course. Now, onto rockets/aerospace!