Rocket Catcher Challenge

This project follows the Engineering Design Process. Confirm with your teacher if this is acceptable for your project, and review the steps before you begin.

Overview and Rules

The objective of the 2025 Science Buddies Engineering Challenge is to build a device to catch a falling rocket so that it lands vertically. If you have not already done so, please watch the introductory video for an overview of the challenge before you proceed. To enter the challenge, you must follow these rules:

Rules

1. The rocket must start above the rocket-catching device and be dropped into/onto the device. It cannot be thrown or launched upward.
2. The rocket and the rocket-catching device must be separate. They cannot be touching or attached to each other at the start.
3. The rocket-catching device must be freestanding on the ground or floor. It cannot be attached to the ground or floor or to any other supporting object or surface, such as a wall or furniture. It cannot start in the air with the rocket.
4. You may not remove material from the standard rocket body.
5. You may attach materials (from the approved list) to the rocket body.
   1. Anything that is attached to the rocket body counts as part of the rocket and must follow all of the other rules.
   2. Any materials you use to modify the rocket body count toward your total materials cost.
6. No part of the rocket may touch the ground or any other objects (walls, furniture, etc.) during a test.
7. Your rocket-catching device must catch the rocket on its own. After the rocket has been dropped, nobody can touch the rocket or the rocket-catching device, or somehow assist the device in catching the rocket.
8. After all parts have completely stopped moving, the lowest point of the rocket, including all attachments, must be at least 10 cm from the floor (measured perpendicular to the floor), as shown in Figure 4.
9. After all parts have completely stopped moving, the rocket’s main body must be vertical. “Vertical” is defined as an angle at least 45 degrees from horizontal, as shown in Figure 4.
10. You must complete 2 successful drops in a row from the same start height, with the same rocket and the same rocket-catching device (repairs in between trials are allowed).

Figure 4. Diagram for challenge setup and measuring distances and the landing angle.

Design

Before you start building anything, it is a good idea to brainstorm different designs. If you need help getting started, look at some of the designs in the Introduction and re-watch the introduction video. Try sketching your designs out on paper (paper used for sketching does not count toward the total used to build your device). Remember that your design must include a ground-based device to catch the rocket. Modifications to the rocket body itself are optional but may help your design succeed. Also remember that there are some potential trade-offs in your design. You might be able to build a bigger, sturdier design that can more easily catch the rocket when it is dropped from a higher height, but doing so may require more materials. Your score depends on both the distance your rocket falls and how many materials you use. 

Build

Once you have a design, it is time to start building. You may find out that your design does not work out as planned once you start building, and that is OK! You can go back and change parts or even all of your design. Only materials used in the final design that you test count when calculating your score, so do not worry about using extra materials to build more than one design.

Test

Once you have finished building your rocket-catching device and making any modifications to your rocket, try dropping your rocket into your device from a relatively low start height at first. Here are some questions to ask as you make observations:

1. How does your rocket fall? Does it tumble end over end? Does it flutter randomly? Does it stay pointed in one direction?
2. What happens when your rocket hits your device? Does the device sag, bend, or break? Does the rocket bounce or roll off the device?
3. What happens after everything has stopped moving? Are all parts of the rocket (including anything you attached to the rocket body) at least 10 cm off the ground? Is there any damage to your rocket or device that you need to repair? Is there a risk for additional damage if you drop from a higher start height?
4. Does your rocket land vertically? As shown in Figure 4, the rocket's landing angle must be at least 45 degrees to count as "vertical."
   1. To check if your rocket's body is at an angle of at least 45 degrees, cut a piece of paper into a square and fold it in half diagonally to form a triangle with two 45 degree angles.
   2. Hold the triangle up to your rocket, with the bottom (short) edge of the triangle parallel to the floor. Your rocket's body should be steeper than the diagonal (long) edge of the triangle (Figure 5). If the rocket's body is at a shallower angle than the long edge of the triangle, then the landing angle is less than 45 degrees (Figure 6).

Image Credit: Ben Finio / Science Buddies

Figure 5. A paper triangle used to confirm that the rocket's landing angle is more than 45 degrees. This attempt counts as a successful vertical landing.

Image Credit: Ben Finio / Science Buddies

Figure 6. An unsuccessful landing with a landing angle of less than 45 degrees. 

Based on your observations, try to make improvements to your design, testing from higher and higher start heights, until you are ready for an official test. 

Official Test

When you are ready for an official test:

1. Measure the fall distance. As shown in Figure 4, this is the vertical distance between the topmost point of your rocket-catching device and the lowest point of the rocket at the start. There are two ways to find this distance:
   1. Measure the distance directly using a tape measure or meter stick.
   2. If you find it easier to measure from the floor, then:
      1. Measure your rocket's start height (the distance from the floor to the bottom of the rocket).
      2. Measure your rocket-catching device's height (the distance from the floor to the topmost point of the device).
      3. Subtract the device height from the rocket start height to get the fall distance.
2. Drop your rocket, making sure you follow all of the rules listed above.
3. Measure your rocket's end height (from the ground to the lowest point on the rocket, including anything you attached to the rocket's body) and make sure it is at least 10 cm.
4. Measure your rocket's landing angle as shown in Figures 5 and 6 and make sure it is at least 45 degrees.
5. If your test violated any of the rules, you must start over and do a new test.
6. Repeat the test to make sure you get two successful drops in a row.
7. If your test was successful, you can still re-test as many times as you want to try and get a higher score (you must get two successful drops in a row from each new height). Move on to the next section when you are ready to calculate your score. 

Scoring

Your score is then calculated using this equation:

Equation 1:   $\: Score\; = fall \; distance \;in\; centimeters - total\;materials \;cost$

A scoring worksheet and scoring spreadsheet are available to help you calculate your score. You can also read the following written instructions or watch the video with an example calculation.

https://www.youtube.com/watch?v=FQy8cAU8SW4

1. If you measured your distances in inches, convert them to centimeters by multiplying by 2.54. For example, if your fall distance was 40 inches, that is 40×2.54 = 101.6 cm.
2. Count the total number of each material item that you used.
   1. Material quantities are not prorated. For example, even if you only use one quarter of a sheet of paper, you must count the entire sheet.
   2. Remember to count materials used for both your rocket-catching device and additions to your rocket's body.
   3. If you used a rolled sheet of paper for your rocket's body instead of paper towel or toilet paper tubes, that sheet of paper does not count toward your total.
   4. Only count materials used in your final design for both your rocket and rocket-catching device. Materials used for earlier prototypes do not count.
3. For each material, multiply the quantity by the point cost for that material to calculate the subtotal for that material. For example, if you used 6 sheets of paper, which are worth 3 points each, that is 6×3=18 points. The material cost is 18.
4. Add up all of the subtotals to get your total materials cost. For example, a design that used the sheet of cardboard, 6 sheets of paper, tape, 2 paper clips, and 70 cm of string would have the following materials cost:
   1. Tape is "free" (0 points)
   2. 1 piece of cardboard = 5 points
   3. 6 sheets of paper × 3 points each = 18 points
   4. 2 paper clips × 1 point each = 2 points
   5. 70 cm of string:
      1. First, round up to the nearest 100 cm, so 70 cm rounds to 100 cm.
      2. 100 cm × 2 points per 100 cm = 2 points
   6. Total = 5 + 18 + 2 + 2 = 27 points
5. Plug your fall distance in centimeters and total materials cost into Equation 1 to calculate your score. For the design in the example above, with a fall distance of 101.6 cm and a total materials cost of 27 points, the score is 101.6 - 27 = 74.6.
6. Round your score to the nearest whole number. The score of 74.6 would round up to 75. If the score was 74.49, that would round down to a final score of 74. The score submission form will not accept decimals.