Welcome, Cadet!

Rocketry is a great way to get outside and be creative. There are plenty of ways to launch your ideas - from homemade rockets made of household materials, to more sophisticated rockets that can reach heights of hundreds of feet. In this introductory class we'll take a look at a few types of rockets, and how they operate, to get you on your way to being a space ace.

The supplies required for each project are at the beginning of every lesson, and all compiled here for reference:

Stomp Rockets

• ½" PVC pipe (about 10')
• 1x ½" PVC 90-degree slip-on elbow or 1x ½" PVC 45-degree slip-on elbow
• 2x ½" PVC slip-on end cap
• 1x ½" PVC slip-on 4-way splitter
• 1x PVC 1" to ½" reducing bushing
• PVC cement
• Hot glue
• Cotton balls
• Tape
• Lots of 8½" x 11" paper

Pump Rockets

• Bike pump
• Sports ball inflation needle
• Fun patterned duct tape (optional)
• Markers

Lazy rockets if you don't want to DIY (screw-on water rocket fins)

Model Rockets

• Model rocket launch set
  
  • Launch pad
  • Rocket
  • Launch controller
  • Rocket igniters
• Rocket engines (start with the smallest "A" type)
• Recovery wadding (aftermarket add-on)
• Shock cords (aftermarket add-on)
• 18" parachute (aftermarket add-on)

Safety is critical when doing any rocketry. All rockets work with propulsion, which is usually explosive in nature. In this class we're dealing with pressure difference and chemical reactions, which are safe, but still need some safety measures.

Taking precautions doesn't mean any less fun. In fact, safety increases fun as it means that no one gets hurt during your experiments. Always work within your comfort zone, with respect for the components you are working with, and with an adult present when it's necessary.

Though you might not need a lab coat and pocket protector, eye and hearing protection for you and your crew is required.

A rocket is any kind of projectile that uses a rocket engine to produce thrust. In the scope of this beginner class we're going to widen the definition of rocket to any projectile that is launched and achieves thrust by any means.

Using a more broad definition of what rockets are, we can explore a few different methods of making our own rockets and learn about some basics of weight and shape. At the end of this class we'll look at the classic definition of a rocket and use real engines to launch a rocket into the sky!

There are lots of different types of rockets, and constant advancements in technology means that there will likely always be new types that are different than what came before. Using the very basic definition, here's what most rockets look like.

_{Rocket image modified from Wikimedia Creative Commons}

The engine portion will be what we explore most, starting with a simple and approachable method of launching rockets and then progressing through more challenging rockets to end with a bang.

_{Rocket image modified from Wikimedia Creative Commons}

Throughout this class you're sure to have some rockets that perform better than others. There's a lot that goes into rocket design, and small changes in any one area of the rocket can produce a dramatic difference in performance.

To get the most out of your rocket you'll need to keep a few things in mind:

Drag

The frictional force of air acting against the direction of motion is drag, which slows the rocket down. While your rocket is in flight it will be pushing air out of the way.

Center of gravity

The point at which the rocket weight is balanced. Try resting a pen across one finger, where it balances without falling off is the center of gravity. Your rocket will have a center of gravity that will likely be in the fuselage, you can move the center of gravity by adding or taking away weight from the nose cone.

Center of pressure

The point where the total sum of air forces act against the rocket. When in flight, the rocket engine is applying force upwards, while gravity and drag apply force downwards. The center of pressure is the sum of these forces in relation to the center of gravity. In rocket design, you want the center of pressure below the center of gravity to achieve the best performance.

Stability

Rockets need fins to help stabilize the trajectory while in flight. As air passes over the rocket the fins are parallel to the direction of motion. If the rocket begins to tilt, the air will catch the flat side of a fin and the force of air will push the fin downwards to be parallel with the direction of motion. With multiple fins the rocket maintains its direction while in flight.

Put your knowledge to the test, try the quiz below and see how you do!

{
    "id": "quiz-1",
    "question": "What safety items should you wear when launching rockets",
    "answers": [
        {
            "title": "Safety Glasses",
            "correct": true
        },
{
            "title": "Watermelon helmet",
            "correct": false
        },
        {
            "title": "Labcoat",
            "correct": false
        }
    ],
    "correctNotice": "Correct! Eye protection is always needed when launching anything. Make sure you have enough for the spectators, too!",
    "incorrectNotice": "Nope. But, you can wear that if you like and look extra cool."
}

{
    "id": "quiz-2",
    "question": "Which is NOT part of a rocket?",
    "answers": [
        {
            "title": "Nose cone",
            "correct": false
        },
{
            "title": "Mr.Coffee",
            "correct": true
        },
        {
            "title": "Fuselage",
            "correct": false
        }
    ],
    "correctNotice": "Correct! Mr.Coffee isn't a required part of a rocket.",
    "incorrectNotice": "Are you sure?"
}

{
    "id": "quiz-3",
    "question": "Good rocket design has:",
    "answers": [
        {
            "title": "The center of gravity above the center of pressure.",
            "correct": true
        },
        {
            "title": "The center of pressure above the center of gravity.",
            "correct": false
        }
    ],
    "correctNotice": "Yes! Rockets work best when the pressure is pushing the center of gravity.",
    "incorrectNotice": "That's incorrect."
}

That's it for the theoretical side of rocketry, time to do some practical engineering!

Next lesson, we'll start with the most accessible type of rocket to get you into applying the basics. Strap in, Cadet. Time to blast off!