Rockets! They fly high. They fly fast. They usually contain parachutes. (This one doesn’t) All things I love. Getting to share these awesome launch experiences with Alex makes it all that much better. He’s the official launch controller, and my function is flight director.
We’ve launched 5? different rockets about 8 times in the past month, and the picture above is a thumbnail of an upcoming video on my YouTube channel. Rocket design is something that anyone can do, and in my playlist about rocket design, I show you what you need to know in order to design and fly rockets successfully. I’d say that “safely” is included within “successfully”, so that’s why I didn’t mention that word in the previous sentence. But now I have. So there.
The key thing about model rocket engineering is STABILITY. A stable rocket is safe, fast, and predictable. All of the recent rockets I’ve designed are somewhat radical to show what’s possible, and each of those will be featured on my Rocket Science playlist in the coming weeks. Let’s make this an actual informative blog post. New paragraph.
A model rocket is supposed to go up where you point it, then come back down in about the same area from where it left. The first challenge is going up.
In order to go up, you need enough thrust to get off the pad. Thrust is provided by model rocket motors, and there are several sizes that can be chosen commercially. 1/2A through F. ( at Hobby Lobby typically) Once you’ve selected your motor, then you can begin to design your rocket. Obviously, your rocket must not weigh too much or your selected motor will not lift it. Rockets do not rely on lift so they have to weigh less than the thrust provided by the motor.
Stability is the safe part of rocketry, so that’s next. Once your rocket leaves the launch rod, it needs to keep going in the direction the rod was pointed. In order for this to occur, the mass and area of the rocket must be located in certain spots. The point where all the mass can be considered, and where the rocket will rotate around is called the center of gravity, CG. The point where all the air acts upon is called the Center of Pressure, CP. I discuss the Centers of Gravity and Pressure in several videos.
The rocket needs to be designed so that the CG is about 1-3 body tube widths ahead of the CP. This ensures a stable rocket. The videos mentioned above show you how to do this. I’ve also got a Rocket Designer spreadsheet on the downloads page that does most of the heavy calculating for you. So if you’re not terribly math inclined, so over and download that Excel file and get flying!