The RTH rocket (Return To Home)
The Return To Home rocket has been a slow burning project. The model this rocket is based on is a modified V2 Rocket from ESTES model Rockets. The reason we chose this model is due to its thick diameter, which allows for some nice 3D printed internals to hold servos, flight control systems, and any sensors we wish to incorporate. This is a sectional model meaning that each section can be developed independently to work within a standardized system that will ultimately control every aspect including its main feature which is RTH (Return To Home); Essentially making it a fire and forget rocket that will return back to launch point automatically regardless of flight height. This will allow us to have a smaller launch team, better tracking, better telemetry, and better videos, all while getting enough data to tweak the system and allow us to perfect it from 30 meter RTH accuracy to 5 meters accuracy. Another reason that we chose this model is because of its design which makes calculations a bit easier.
Some early design aspects of the RTH rocket include, shock absorbers during chute deployment, reinforced mounting points, rotor system section for chute control, standardized engine bay for different high powered engines with a standard diameter. This allows us to source larger quantities of engines for testing at a better price.
The image above shows one of three points in the engine section of the rocket. These points will be reinforced to take substantial amounts of heat repeatedly without wearing out. At the bottom of the image we reinforced the rubber band (shock absorber) mount and used some of the plastic that essentially turns into part of the glue to have a non-sharp edge that will be in contact with the rubber band at all times. A similar method will be used on the above unfinished section. The type of glue used to make it was Gorilla glue, the transparent one that does not require water to activate. This section took over 4 days to dry completely. Eventually, these prototype parts will be 3D printed once tested, and re-tested as easy assembly of the rocket is one of the developmental criteria for this model.
So, this was the first time I had tried fiber-glassing anything in my life, and it shows. I figured it would be as easy as buying the correct fiber-glassing kit and WALA. I am glad to inform everyone that fiberglassing is a crucial step in our development process and it was not easy. In fact, I even decided to correct these mistakes instead of trashing it and restarting; this way I learn how to correct such novice mistakes.
The nozzle end of the rocket was also reinforced. Same process with this one we created a standard mount with Gorilla Glue. The estimated thickness of the part is about 5mm thickness. This allows for it to remain lightweight while providing enough material to allow additional sensors to be mounted at each section which will allow us to record every aspect of flight, including chamber temperature at time of ejection charge activation; if the thermistor survives.
In the image below you can better see the excellent method with terrible implementation of the reinforcement of the Section 1 of the rocket.
One of the final goals of this model is to be a Modular Test Bed for future systems. Ultimately this may not be the rocket used for our 100,000ft up test flight, but for now it provides an excellent testing rocket with predictable outcomes, which is part of that consistency we are looking for to ensure our data collected is the best and most accurate data we can collect on each test flight.
Thoughts on not yet developed systems such as multistage testing
The first thought on multi-stage is to take this stage (pictured above) and place it in a round saw to divide into sections and then modify each connecting stage point. The second thought is to begin designing a two-stage version seperately using the same components as in the first one, but with better implementation.
Another good option is to finish building this one out and use it on single stage testing before putting it to the bandsaw. My initial concern with doing this is that due to my lack of proper implementation of the different processes through out the build that it will end up being too heavy for just a single E sized engine which is what the initial test will be with. Putting it to the bandsaw would allow me to create more space for a multi-engine second stage; again, this raises the concern of too heavy to get off the launch pad. Another back up random thought is adding a custom booster lift off stage. Something that allows power over precision.
Steps still needed to complete RTH rocket section 1
- Clip all bubbles (meaning cutting them out with an exacto blade in prep for sanding.)
- Sanding the model to re-even the terrible fiberglassing job initially performed.
- Clipping all the excess dried up fiberglass and smoothening it enough to get ready for another coat.
- Re-glassing the rocket. This time avoiding excess mixture and custom cutting the fiber, as well as using a vacuum for better form.
Section 2 of the rocket will be the front end initially. This section is planned to contain the parachute testing component and first prototype section to form completion of the most basic systems we will be testing, launch systems, and recovery systems.
About the parachute we will be using.
We have purchased (pictures to come) an acrobatics parachute/kite used for flying in the beach. This chute isn’t designed for rockets. My current goal is to adapt a 5.5ft wide airfoil chute as the means of travel back to home system. Through some playing with these parachute/kites the idea was just there. We are going to control this much like a wing following point of origin, so a kite will be the best type of “chute” we will need. We will be using a flight controller system (likely an F722 wing controller). Ultimately, the parachute will be steered by a 3D printed mount that will be hooked up to some servos. We will use 2 servos/2 channels in glider mode to ensure that it steers as a flying wing. In reality this is the easy part, and fun part. Our definition of success will be to launch the rocket with a wide variety of motors of different power and stages, and it returning within 10 meters of our location. Software accuracy says it can do 2ft accuracy, but I will be happy with 10 meters during initial testing.
Launch pad update:
I have discussed plans with a friend that does excellent quality wood working, and he has stepped up to do the woodwork for it. I will be responsible of delivering sketches at absolute worst of the idea and allowing him to implement it. For the launch station I am thinking that the design will be able to accommodate a Orange PI5 development board with many sensors to measure as much data as possible from the launch systems perspective, giving us another set of data that can be analyzed to increase performance. In addition to being able to log data, it will also be able to record video from the 3 inputs the board has. The PI Cameras aren’t great, however they are good enough for what we are looking to do. Having them automatically connected to a octo processor is just the best idea possible as it allows for simultaneous recording of the tracking, launch pad, and a secondary view of the launch pad or FPV video. This also allows for an output to a set of goggles via usb c plug. This means we would be able to select a camera and watch it on an FPV goggle system.
Update: 1/6/2023
I have several ideas in mind, but recently have started thinking of the portability aspect of the launch pad. Ideally, we would want this to fit in a backpack with the rest of the equipment. This way a single pack can hold the entire experiment. This honestly makes going out to launch rockets much more fun due to not having to do 10 exhausting trips to launch site with equipment. This in my observations is one of the biggest gripes I hear on the field. As a fun-centric team we want to make sure to keep the burdens down and the fun up!
The Para-wing
After 3 months of waiting, it finally arrived as you see it pictured above. It did come with instructions for its proper use as a stunt kite. The reason this option is the best in our opinion is that in order to be able to “reach the target landing site regardless of altitude” means that at some point it will need to “fly”.
With the airfoil on this kite we should be able to do exactly that and at very least extend flights on a ration of 3:1. This means the rocket would glide forward 3ft for every 1ft drop in altitude; which would essentially fill the “fly” aspect of our requirements. This of course would be our minimum requirement for a decent controllable glide slope on the way back to launch point. Currently we will be going out this upcoming Sunday to test out this kite as it is intended. While we are out there, we will be measuring the strength of the kite, how much drag/lift it provides, all while we have the time of our lives with our three and six year old son’s at Florida beaches early morning to catch that soft morning breeze.
- ESTES Universal Astrocam HD Rocket Camera & Holder
- Phase 1 of the launch system.
- Typhon 6S Exploded View
- Typhon 3S Exploded View
- AllSkyPi, and what it does
