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NEEDS PICTURES AND LOTS OF EDITS

This article goes through the basics of designing a mid- to high-power rocket.

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A rocket generally has three physical body sections:

1. Nose cone
   1. For aerodynamic purposes
   2. Usually empty or capped for smaller 3" rockets
2. Body
   1. To contain recovery, avionics, and payload, and to transmit loads and for aerodynamic purposes
   2. Usually subdivided into two or more tubes. Subdivision usually depends on the recovery system and payload.
   3. Usually a 3" body tube (2.6" and 4" are also common) for L1 flights
      1. The dimemsion 3" refers to the inner diameter of the body tube. 
3. Motor section/Fin can
   1. To contain motor, provides stabilization via fins (usually)

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For our example, we will be designing based on a single separation, single deploy (SSSD) system. For most flights under 3000 feet, and most Level 1 (L1) flights, SSSD is fine. We do not need to separate any of the three airframe sections above for a successful flight. Let's use a 3" body tube with a relatively arbitrary length of 15". The basis for a motor section is also a body tube, so let's add another one below it. For this rocket, we will also make the nose cone the same diameter as the body tube. It should look like this:

OpenRocket PART 1

Add a shoulder to the nose cone, a coupler between the 2 body tubes, and an inner tube at the bottom of the rocket for the motor mount tube. Couplers are typically 2 diameters long, and motor mounts ~6-8 inches long. So now, we have something like this:

PICTURE 2

Add some centering rings for the some mass objects for any payload you want, including altimeters and so on.

To model the rocket flight, you'll need a fins, a motor and a chute. For the motor, set the inner tube to a motor mount, and select a motor. (If this is your first time: Aerotech H250) Note: make sure the motor mount tube is the correct diameter for the motor you plan on using! You might notice some funky results if you don't have fins yet.

 SO: add some fins. Protip: watch the CP on the rocket move while you edit the fins. To start, you want a stability margin ~2 calibers in the little window on the top right of the rocket diagram. This is not your absolute stability. (see Stability for more.)

Last - the chute. For now, it is recommended to put the chute in the body tube adjacent to the nose cone. Find some chutes in lab to get a good idea of chute masses and sizes. OpenRocket will estimate your descent rate based on your specified chute - getting an accurate model is best. (However, it does not do a good job of modeling chute-less tumbling with two tethered pieces - so estimates are better for big chutes)

So now, you should have something like this: (Results may vary)

FINAL OPENROCKET

Now, simulate the flight. OpenRocket will flag events it thinks aren't great - and you can fix the rocket accordingly. Sometimes, the warnings are relatively trivial - it's a good idea to confer with an experienced RT member here.

Now - if this was your first time - save this file, and start a new one. See what you can come up with.