5 reasons to put electronics into your rocket

I’m just beginning to learn about the different kinds of electronics that can go into a rocket. It seems like there are virtually limitless possibilities, but I’ll give a quick overview below.

TeleMetrum v3.0 flight computer chip sitting on stone backdrop
TeleMetrum v3.0 flight computer

A high power rocket often has an electronics bay (“e-bay”) or some payload area where you can put various types of payloads, generally electronics.

The options are really endless, but just to help provide some overall context, here are a couple of the major types or categories of electronics that can go into a rocket.

An empty electronics bay made of wood with metal screws and rods
An empty e-bay
  1. Altimeter. This is a simple device that measures altitude, or height. It uses changes in barometric pressure to determine height (starting by setting it to zero at the launch site, so that it has a starting point). It’s fun to launch a rocket, but it’s nice to know exactly how high it goes. I’ve heard great things about the RRC3 from MissileWorks, for example, as well as the StratoLoggerCF altimeter.
  2. Parachute release. If you wrap the parachute with a rubber band so that it’s closed tightly, it won’t automatically open when it’s released at peak height. By using a very small chip, such as the Chute Release from Jolly Logic, you can control when that parachute actually opens up and deploys.
  3. GPS/ radio beacon. It’s helpful to know exactly where your rocket goes, using something to record position data. It’s also helpful for finding your rocket after it inevitably disappears from sight and you have no idea where it landed. I’ve heard several people recommend the BeeLine GPS, for example, from Big Red Bee.
  4. Flight computer. This is a small chip (e.g. the one pictured at the top of this page) that integrates several useful functions into a single device. A flight computer generally contains an altimeter and GPS/ radio beacon, but also contains “pyro channels” which can control parachute deployment. A flight computer allows a rocket to “dual deploy,” meaning you can deploy two separate parachutes, and you have a greater degree of control over when the rocket parts separate and the parachutes actually deploy. The flight computer pictured above is the TeleMetrum, from Altus Metrum.
  5. Camera. Is there any limit to how creative you can get with putting electronics into a rocket? Not really! I’ve just begun to scratch the surface, but I know people put a GoPro or other camera on the outside of the rocket and record video during launch, so that you see the earth receding underneath. For some of the biggest rockets, you can even glimpse the horizon and the edge of the earth’s atmosphere.

My initial goal is to just figure out what I’m doing (I have no experience working with electronics) and put together the basic parts to create a functional e-bay with a flight computer. This is one of my 2020 goals – and specifically a January 2020 goal because I have a lot more to do this year.

High power rocket construction: part 2 (e-bay)

This post is largely meaningless because I’m not actually including any electronics into this rocket, at least for its first flight. I should probably have titled it “How to build an electronics bay without any electronics.”

Meh.

Electronics bay wooden sled
Starting point for building e-bay: the sled

So first, what the hell is an e-bay?

An electronics bay (or “e-bay” for short) is where you attach any electronics that you want to fly in your rocket. It’s also sometimes called an avionics bay.

What kinds of electronics would you want to fly? Well, there are a lot, and it can get pretty interesting. A few examples of things are:

  • Altimeter. Measures the maximum height of the rocket (i.e. its apogee).
  • Explosive charge. If you put black powder on the outside of the e-bay and wire it up with some electronics on the inside, you can manually detonate the charge and cause the rocket body to separate on descent, for another parachute. This is called dual deployment, as you’re deploying two parachutes.
  • Camera. A GoPro camera can be installed on the outside of the rocket body, wired to electronics stored inside the e-bay.
E-bay mostly assembled: sled and coupler tube
E-bay mostly assembled: sled and coupler tube

The e-bay is actually pretty easy to assemble. It’s just a few pieces of wood, and some metal screws, washers, and nuts. You start by gluing together the wooden “sled,” and then sliding two very long metal screws through the slots, along one side. Each end has a circular piece of wood with an eyebolt (which can hook to other things like shock cords and parachutes) and it all stays together with some washers and nuts.

E-bay completed and assembled.
E-bay complete! Minus any electronics.

Now, if I actually had any electronics in this thing, it’d be more interesting. But I built it anyway for two very important reasons:

  1. It’s necessary to act as a coupler and keep the rocket body together so it can fly in one piece. Without this, there’s nothing to connect the top and bottom halves of the rocket.
  2. I plan to add electronics to this rocket for future flights.

So there you have it. Not your granddad’s e-bay.