It’s really easy to lose a high-power rocket. Sending a rocket thousands of feet up into the atmosphere in only a few seconds means and you can:

There are ways to mitigate each of these occurrences but having a tracking device of some kind helps lend peace of mind. No one wants to lose a rocket. They are expensive: components, all the time you spent getting things just right, avionics, reloadable motor hardware, etc. And, the whole point of flying a rocket is to get it back and do it again.

In the late 90s and early aughts I used two methods of tracking:

At that time, I only flew GPS telemetry occasionally in the G-RAG 3 rocket because it was a large and complicated payload.

Things Have Changed

Some of the biggest advancements in hobby rocketry in the past 20 years have been in electronics. They have gotten dramatically smaller, more sophisticated, and cheaper (at least in some cases). This is due, in part, to a proliferation of:

Because electronics vendors for hobby rocketry are themselves hobbyists or small businesses there is a lot of turn-over. Virtually all the vendors I bought electronics from 20 years ago are out of business. Some are even zombies–I’ve come across several websites that appear to have products for sale but links are broken or pages haven’t been updated in years. You can still use electronics after the vendor has closed its doors but the control software (if there is any) will gradually become incompatible with modern computers.

Between 2001 and now, independent of hobby rocketry, smartphones have gone from not existing to being our de facto computing devices. I would prefer not to have to lug a laptop out to the launch site and have it set up next to an effectively immobile1 ground station when I have a smartphone in my pocket. Despite this, most rocketry electronics either assume you will use them with a PC or they implement functionally that could be provided by a smartphone app in a proprietary way.

Commercially Available GPS Trackers for Rocketry

John Coker has a good write-up of GPS trackers c2015 it goes into a lot of technical detail. Start there for a good overview and an excellent discussion of antenna gain mechanics. However, it only covers a few products from 3 vendors–there are a lot more options out there. Here is a survey of what I could find from scouring the Internet:

Another alternative is to get a cheap/used Android phone and use the Insane Rockets app to beam back telemetry information via a cellular data connection. (Phones are only suitable payloads for large rockets.) This also assumes there will be cell service at your launch site–most fields big enough for rocketry are in rural areas which can have poor network coverage.

There are trackers in the consumer electronics market that could be repurposed for rocketry like this LoRa/GPS from Seed Studio, a GSM/GPS units from Trackimo, or even an LTE-M/WiFi/GPS dog collar from fi. These have design goals that line up with their intended uses so they usually make one or more of the following trade-offs that make them less than ideal for rocketry:

These aren’t deal breakers, but I haven’t found any consumer products that are dramatically cheaper for a whole system: transmitter, receiver, phone interface and makes good design trade-offs. A possible exception are GPS trackers meant for falconry (yes really) like those from Marshall Radio but a full GPS system can easily add up to north of $1500.

TLDR

For my needs (small, light, works with a phone as a ground station), the best options are:

  1. Missile Works T3 (RPSMA version with 4.7” rigid 1/2 wave dipole antenna), ~$170
  2. GPS tracker by Featherweight Altimeters, ~$350 (the only problem is I don’t have an iPhone)
  3. FlightSketch SST–only an announced product, not yet available

State of Android Apps

I spent a lot of time trying to find Android apps that would work with the Missile Works T32. Ideally, the app would do three things:

  1. Track the GPS location of the transmitter (received via Bluetooth)
  2. Track your current position based on the built-in phone GPS
  3. Plot the heading and report the distance between your position and the beacon’s position

Of the three apps recommended by MissileWorks, only RocketLocator is still available in the Google Play Store and it appears to meet the functional criteria. It is built around the BluetoothGPS4Droid (SourceForge) (Github mirror) library for interacting with Bluetooth GPS modules. That library hasn’t been updated since 2013 and uses a backport of a deprecated Bluetooth API to work with modern versions of Android. This isn’t great but if it works, it works. The app itself was updated in 2019 with compatibility fixes–so that’s a good sign–but it looks dated and is a bit rough around the edges.

The next best option is to split the tasks up across multiple apps.

Transmitter tracking

Android does not have native support for Bluetooth GPS devices–you need to rely on a third-party app. I found several apps that claim to support this but by far the most common recommendation is Bluetooth GPS (Garmin even recommends it for use with their Glow 2 Bluetooth GPS). Unfortunately, the app hasn’t been updated since 2015 and appears to be completely unsupported–it’s starting to become incompatible with recent versions of Android. That doesn’t look good.

Bottom line: I can’t confirm if the Missile Works T3 is compatible with Bluetooth GPS on Android 10 and if it doesn’t work there aren’t any other good apps out there to fill this need3.

As an alternative, it may be possible to connect a Window laptop4 to the ground station via GPSDirect5.

Phone tracking

GPS Status is an excellent tracking app.

  1. I mean, you could drive it around in a car if you wanted. Assuming you have at least a driver and someone to monitor the ground station. Also, you would need to be able to drive where you needed to go, which is frequently not the case when chasing rockets through farm fields, etc. ↩

  2. I’m trying to get the app situation sorted before I buy it or recommend that others do the same. ↩

  3. There are lots of apps that make the GPS on your phone available over Bluetooth for other devices. You can still get tablets without built-in GPS but apparently, the market for apps that consume GPS-over-Bluetooth isn’t big enough to attract a lot of app developers. ↩

  4. The GPD MicroPC comes to mind as a good option for a mobile ground station. ↩

  5. Most Bluetooth GPS devices don’t work out-of-the-box with Windows either. It seems pretty common for Bluetooth-enabled GPS modules to simply treat the Bluetooth connection as if it were a serial data connection. The data feed needs to be parsed and translated into something that the location services part of the operating system can understand what is going on. ↩