We’ve become so used to seeing SpaceX boosters land themselves back on the pad with clockwork reliability, that it’s easy to forget it took them a good number of attempts to get right. Inspired by SpaceX’s work, [Joe Barnard] of [BPS.Space] started working to replicate it at the model scale five years ago, with no engineering education or experience. On the latest attempt with a brand-new thrust vectoring Scout E rocket, he has gotten tantalizingly close to doing a controlled propulsive landing with a solid-fuel rocket motor.
We’ve all been thrilled to see the SpaceX rockets return to earth, landing elegantly on a floating pad. But those are liquid-fueled. The trick with a solid-fuel rocket motor is it can’t be throttled directly, which is a challenge when you need precision control to land. Thanks to [Joe]’s custom AVA flight computer and the remarkably consistent thrust curve of the Estes F15 black powder motors he used, it becomes a matter of igniting the descent motor at the right moment to make the vertical velocity zero at touchdown. However, [Joe] found that the time between sending the ignition signal and when peak thrust is reached was inconsistent, so he had to work around that. He did this by controlling how much of the thrust is spent in the vertical direction, by vectoring the motor side to side to spend some trust horizontally.
In this attempt, the rocket tipped over on landing due to excessive horizontal movement at touchdown. Joe tracked the cause down to a weak GPS signal caused by antenna position and a possible bug in the Kalman filter that fuses all the sensor data for position and velocity estimation. Thanks to incredibly detailed telemetry and logging done by the flight computer, data from every launch are used for future improvements. We are looking forward to the next flight in a few weeks, during which [Joe] plans to tune and test the control software, among other minor improvements.
Almost every single part of this rocket is a display of engineering ingenuity. The landing struts are designed to absorb as much impact as possible without bouncing while being light and quick to deploy. The ascent motor is ejected simply by moving the thrust vectoring mount to one of its extremes, allowing the descent motor to drop into place. The rocket also features a complete emergency abort system with a parachute, which can be activated manually, or by the flight computer if it calculates that landing isn’t feasible. We already covered [Joe]’s latest launch pad, which is a very interesting project all by itself.
When you’re building and launching a variety of advanced model rockets like [Joe Barnard], you don’t want to spend time building (and debugging) specialized flight computers for every rocket configuration. This challenge has led him to create AVA (All Vehicle Avionics), an impressive model rocket flight computer that he intends to use on all his future rockets.
All of [Joe]’s rockets feature active stabilization and guidance, and comprehensive telemetry using a variety of sensors. On the board there are three separate microcontrollers connected over I2C or SPI, each with its own micro USB port. The two smaller microcontrollers are both ATSAMD21s, also used on the Arduino Zero. The first is used for GPS and inertial navigation, and uses data from onboard and external sensors like the two IMUs (one is a backup), GPS and barometer to estimate the rocket’s position, velocity and attitude, The second is for telemetry, and it handles all external communications via a Bluetooth modem or long range 900 Mhz radio. The main processor (MPU) is a NXP MK20DX256 (also used on the Teensy 3.2), which receives data from the other microcontrollers and handles all the real-time operations and control outputs.
[Joe] gives a very detailed overview on the board, it’s capabilities, and the reasoning behind some of his design choices in the video after the break. Most of the sensors and microcontrollers were selected partly because of his experience with them. All three microcontrollers have Arduino bootloaders, also due to familiarity with the framework. AVA is the 12th in the line of flight computers [Joe] has built, and it is clear that a lot of work and hard-earned experience went into the design. Continue reading “Advanced Model Rocket Flight Computer Reaching For The Stars”→
When you’re building advanced rockets as BPS.Space are, an unreliable launchpad is the something you really don’t want to be struggling with. [Joe Barnard] is working on a model rocket that can land vertically under its own power, like the Falcon 9, and has upgraded his launchpad in the process. A lot of thought and hard-earned experience has gone into its design, and the video after the break is a fascinating look the engineering process.
[Joe]’s rockets don’t use guide rods and fins for stabilization in the way most amateur rockets do, but instead have thrust vectoring motor mounts and reaction wheels for active stabilization during launch and flight. The rockets are clamped to the launchpad right up to ignition, and then need to release quickly and reliably. His previous clamps looked very cool, but suffered from high friction forces during release, and the integrated covers prevented easy inspection. These were replaced by much simpler spring-loaded clamp held in place by a small locking bar, which is knocked out by a servo to release the clamp. It also has no static friction, since it moves up and away from the clamping surfaces on the rocket.
The launch pad also features a ATSAMD21 based launch computer named Impulse, which at the most basic level controls the igniter, clamps, buzzer and indicator lights. It also has a number of inputs and outputs to allow for expansion. [Joe] experienced a number of inexplicable failures of rocketry electronics in the past, but believes he has finally tracked down the culprit: Tennessee humidity. He has since started conformal coating all his electronics.
The launchpad itself is made from plywood, so to protect it from the hot exhaust it has in integrated flame trench. This was made from 1 inch steel plumbing components, and directs most of the exhaust out of one side of the platform. It can also be reconfigured to allow a three core rocket like a Falcon Heavy to be launched. Continue reading “The Ultimate Model Rocket Launchpad”→
[FastEddy59] is in the middle of building a model rocket complete with a Thrust Vector Control (TVC) system to help with stabilization. Much to our delight, he’s designed an equally ambitious controller to spice up the launch sequence with security codes and a physical key. And what’s a launch controller without a giant emergency stop button to shut down everything? Incomplete, if you ask us.
Under the carbon fiber-wrapped acrylic hood, there’s an Arduino MEGA engine and an NRF24 LoRa module for transmission to the rocket. There’s even a DHT11 temperature sensor to verify that launch conditions are ideal. It’s still a work in progress with plenty of features to come, like fancier labels and plenty of launch-appropriate sound files for the hidden speaker. There’s a lot to this case, and [FastEddy59]’s video brief is ready and waiting on the pad after the break.
While rockets launched from silos are generally weapons of war, [Joe Barnard] of [BPS.Space] thought model rocketry could still do with a little more thoomp. So he built a functional tube launched model rocket.
Like [Joe]’s other rockets, it features a servo-actuated thrust vectoring system instead of fins for stabilization. The launcher consists of a 98 mm cardboard tube, with a pneumatic piston inside to eject the rocket out of the tube before it ignites its engine in mid-air. When everything works right, the rocket can be seen hanging motionlessly in the air for a split second before the motor kicks in.
The launcher also features a servo controlled hatch, which opens before the rocket is ejected and then closes as soon as the rocket is clear to protect the tube. The rocket itself is recovered using a parachute, and for giggles he added a tiny Tesla Roadster with its own parachute.
Projects as complex as this rarely work on the first attempt, and Thoomp was no exception. Getting the Signal flight computer to ignite the rocket motors at the correct instant proved challenging, and required some tuning on how the accelerometer inputs were used to recognize a launch event. The flight computer is also a very capable data logger, so every launch attempt, failed or successful, became a learning opportunity. Check out the second video after the break for a fascinating look at how all this data was analyzed.
[Joe]’s willingness to fail quickly and repeatedly as part of the learning process is a true display of the hacker spirit. We’ll definitely be keeping a close eye on his work.
Launching model rockets is fun, but the real meat of the hobby lies in what you do next. Some choose to instrument their rockets or carry other advanced payloads. [seamster] likes to film his flights, and built a nosecone camera package to do so.
A GoPro is the camera of choice for [seamster]’s missions, with its action cam design making it easy to fire off with a single press of a button. To mount it on the rocket, the nosecone was designed in several sections. The top and bottom pieces are 3D printed, which are matched with a clear plastic cylinder cut from a soda bottle. Inside the cylinder, the GoPro and altimeter hardware are held in place with foam blocks, cut to shape from old floor mats. The rocket’s parachute is attached to the top of the nose cone, which allows the camera to hang in the correct orientation on both the ascent and descent phases of the flight. Check out the high-flying videos created with this setup after the break.
Putting payloads into model rockets can be more complex than simply shoving stuff into an open spot, so [concretedog] put some work into making a modular payload tube for his current rocket. The nose cone for his rocket is quite large, so he opted to give it a secure payload area that doesn’t compromise or interfere with any of the structural or operational bits such as the parachute.
The payload container is a hollow tube with a 3D printed threaded adaptor attached to one end. Payload goes into the tube, and the tube inserts into a hole in the bulkhead, screwing down securely. The result is an easy way to send up something like a GPS tracker, possibly with a LoRa module attached to it. That combination is a popular one with high-altitude balloons, which, like rockets, also require people to retrieve them after not-entirely-predictable landings. LoRa wireless communications have very long range, but that doesn’t help if there’s an obstruction like a hill between you and the transmitter. In those cases, a simple LoRa repeater attached to a kite, long pole, or drone can save the day.
We’ve seen [concretedog]’s work before, when he designed stackable PCBs intended to easily fit inside model rocket bodies, allowing for easy integration of microcontroller-driven functions like delayed ignitions or altimeter triggers. Better development tools, hardware, and 3D printing has really helped make smarter rocketry more accessible to hobbyists.