R2Home is a fully autonomous, GPS guided, parafoil recovery system. Its job is to make sure the weather balloon, or model rocket you launch to "the edge of space", comes back exactly where you want it to land! I believe the next space race is about coming back to Earth, in a smart, guided and safe way!

Still not sure about what R2Home really is? I got you covered: just check this video :

I've been working on this project for two years now (and counting!) and I feel like to explain my project in real details to someone I would need a solid 6 month long discussion. But I just started university. So instead I wrote an hackaday page and this intructables page.

This page is about the main "project steps" if you want to get a ready to fly R2Home. For more details about "the project", "the concept", and its "history", you can check this hackaday.io page. If you want to understand the project before reading theses more precise steps, I recommend checking the hackaday page first.

Step 1: Finding Your Wing

One of the main components on R2Home is the steerable parachute wing. The good news is you can use a few different types of parachutes. The first solution if you have a lot of time, and you like spending it on a sewing machine, is to make your own ram air parachute canopy. Don't let it fool you! It's not that complicated! I did it so you can do it too!

If you want to do your own wing, here is a drive folder with a lot of ressources I found on the internet : https://drive.google.com/drive/folders/1Ji09ofrk6...

You have to know that a ram air parachute will be easier to deploy, because the aspect ratio of the wing is low. However, a single skin paraglider wing will have much greater flight performances.

Depending on where you live, and your budget, you might be able to choose between few commercially available single skin RC paraglider wings. You want to find something with a wing area of about 0.8m^2. Here is for example the wing I'm using : http://www.airc2fly.de/swift/swift_de.html

Step 2: The Dbag and Drogchute

All right, so now that you have your wing, you need two other things directly related to the wing. You need a "magic" drogchute, and a dbag (the role of these two parts is explained in detail on the hackaday page). You can really easily make both of them. They are made using F-111 fabric, you will also need some mesh fabric, a tubular cord, a dyneema or kevlar thread.

The drogchute is made out of two round identical pieces of fabric, one out of F-111 fabric, and another one out of mesh fabric. The diameter of the circle is determining the diameter of the drogchute (go for 50cm for a first one). The first step is to sew both pieces flat together. You want to have a seam on most of the circle, while keeping a small space without seam. Then you can turn the whole fabric through the hole you left in the outer seam and you should now have what looks like a flat soccer ball.

The next step is to pass the kevlar thread through the mesh fabric, and sew it on the center of the round piece of fabric made out of F-111. Then you want to sew the tubular cord on the center of the round mesh fabric, you want to make sure you are still able to get the kevlar thread sliding in it after sewing it.

Here is how it should be looking once finished :

For the Dbag you only need to sew a rectangular piece of F-111 in a cylinder of the same diameter of R2Home (3"). But before, you need to sew on it the orange cord you can spot on the picture above. On this cord, there is a loop at the top and at the bottom to connect on one side to R2Home, and on the other side to the drogchute.

On each side of the Dbag, you also want to add a pocket for the wing suspensions lines (see last picture).

Step 3: Folding the Wing

Now that you have your wing, and the Dbag, it's about the right time to learn about how to fold the wing to get a nice deployment. The deployment theory is explained in details on the hackaday project page. Here is about how to fold the wing :

First step is to get it flat on the ground. Then pull the wing and tension all lines. Gather it into a cylinder while making sure the tip of the wing is always either on the top or the extreme side of the cylinder. You don’t want anything (fabric or line) to be after the tip. Then fold the cylinder in half and compress it into the dbag. Finally place all lines in the spot provided for in the Dbag.

Step 4: Assembling the Onboard Computer

Before starting the assembly of R2Home you need your onboard computer! The onboard computer?! Yeah you know that's the guy doing everything for you in flight, well he needs a bit of help to come to life before working for you!

The first and main part you need is R2Home's PCB, all the fabrication files are available (for free of course!) on GitHub. You'll also find a first BOM with the majority of the components you need for the PCB's assembly. This PCB is mainly about connection management and powering, so there are not that many components!

Then it's time to heat up the hot air gun, and place the solder past (make sure you order the stencil with the PCB!) One important point : you might have ordered both straight and 90° JST-GH PCB connectors. Be smarter than me, please, please take the time to think about that point: the wiring between a straight and bended PCB connector is fully inverted. Always double check, even triple check the schematics, and your wiring before powering up anything!

Once the PCB is ready, and you have checked everything, you can already transfer the code (available on GitHub) to the Teensy using Teensyduino. And then you are ready to continue.

Step 5: Building the System

The system itself is mainly composed of 3D printed parts, so the first step is going to be to get all these parts printed out. Since the beginning of the project I've always been using PLA, and it has been working really great. You can find the whole assembly file with all 3D printed parts and all other parts (for free!) on the GitHub page of the project : https://github.com/YohanHadji/R2Home

Here is also a rough list of the necessary parts and tools :

Structural :
- Set of 3D printed parts
- 2 * M4 Threaded rod x 1m
- M3, M4 and M5 screws and nuts
- 4mm thick Aluminium plate
- 3” rocketry phenolic coupler tube (blackcat rocketry)

Electronics :
- Onboard computer :
  - Teensy 4.1
  - R2Home PCB and SMD components
- JST-GH connectors (2, 3, 4, 6 pins, PCB, male, female)
- 3s LiPo battery
- Runcam Split 4
- Matek SAM-M8Q GPS
- BMP280 Barometer
- Parallax 360 Feedback Servo
- 3DR Radio Telemetry Transmitter
- microSD Cards
- 9g Servo
- Ultra Bright NeoPixel RGB led

Getting all the parts :
- 3D Printer
- Press drill
- CNC mill of a metal file

Assembly :
- Screwdrivers
- Zip ties
- Sand-paper
- Multimeter
- Soldering Iron

As soon as you will have all the 3D printed parts, you'll probably need to re-drill all the holes to the right size with a hand drill and metal drills bit. Next up you need to cut the phenolic tube to the right dimensions. It will depends a bit on the evolution of the project, but at the moment I recommend cutting a 22cm long section. I was using a fancy miter saw. But taking the right amount of time to do it right, you should be able to cut it with any hand saw you have in your garage. Once the tube is ready you want to start assembling the locking mechanism. It's the mechanism used to fit the system into its tube.

Remember to check the assembly 3D file if you are unsure about what goes where. It's also about the right time to check this assembly video I did just for you :)

It'll cover almost everything you need to see. However please keep in mind that this video is not travelling in time! R2Home is still in development, and I *unfortunately* won't have the time to make a new one every time. So your #1 reference is always the 3D file! Once the locking mechanism is assembled and working as intended (you might want to sand a bit every moving part to get the perfect fit), you can epoxy the "outer ring" of the locking mechanism in the tube. Don't put to much epoxy, the volume between both diameters is really small, and if you put too much you'll end up having epoxy everywhere in the tube! You also want to make sure you glue it in the right direction! While the epoxy is curing you can start the assembly of R2Home.

Step 6: Testing the System AKA Failing

All right well done! You now have a fully assembled R2Home, you have a drogchute and a dbag, so how the hell can you test it? The first possible test is obviously going to be to power it up and see what happen. If you did your job right, you shouldn't see any magic smoke. In that case, find the problem and go back to step 3.

If this first test is successful, you now have to understand a little bit how R2Home is working. At startup R2Home is not directly ready to fly, you need to wait for initialization. Initialization is when a GPS fix is acquired, and the data quality is considered good enough for a given time defined in code.

On R2Home you have two good friends, the first one is the buzzer, it will beep on startup to say hello world "taaa da daaa", and then while waiting for the GPS 3D fix, it will beep every 5 or 10 seconds with the number of GPS satellites in view. For initialization to happen we need approximately 7 sats. So you are waiting for a "bip bip bip bip bip bip biiip". The second friend is the ultra very mega really bright RGB led.

With the help of the RGB led you can know in which mode R2Home is. And so you can test for example that when you move R2Home up fast enough, it is going in ascent mode, and if for another example, you almost drop R2Home in free fall below the deployment altitude, it will move the deployment servo.

All these tests are easy to make, and easy to repeat (which is what you want to do, test test and test again!) but that's not the main concern. At some point we need to really test R2Home in flight.

First let's understand what R2Home is supposed to do. If you drop R2Home from a given altitude and distance from the desired landing position. It has to deploy the wing at the set deployment altitude, and then steer it autonomously to the desired landing position.

All right so what we want to do is drop R2Home from a given altitude and distance and see what's happening. There aren't that many solution to "drop" R2Home, and I think the best one (and the one I use of course :) is to use a drone. The drone is modified to be able to trigger the "drop" from the ground :

The drone itself is a second hand DJI S800 Evo, you might be thinking "omg this drone is going to cost a huuuuge amount of money" and I was thinking that too. But I got it for less than 10% of its initial price (~1500$), because this drone is kind of really old already, and isn't really useful for videography anymore as technology has really progressed since. And yes you need a drone that big, I was using a smaller drone before, but it was a big chaos. You want something big enough so that there is almost no difference for the drone between flying with or without R2Home.

The next step is obvious, just send it.

The first few tests are for sure not going to be successful, you'll have a lot to learn and some adjustment to make. Your advantage is that you know you can do it because a 17 year old guy could do it. And also that I will always be there to help you succeed :)

This was the starter guide to get you started and motivated to make your own R2Home, thanks for reading it, I really appreciate! I hope you'll be joining the adventure soon and help us make from R2Home a useful and used system. Facilitating science and helping us explore the world.