model rocketry

Retrotechtacular: Junior Missile Men Of The 1960s

Just like the imaginative kids depicted in “Junior Missile Men in Action,” you’ll have to employ a fair bit of your own imagination to figure out what was going on in the original film, which seems to have suffered a bit — OK, a lot — from multiple rounds of digitization and format conversion. [GarageManCave] tells us he found the film on a newsgroup back in the 1990s, but only recently uploaded it to YouTube. It’s hard to watch, but worth it for anyone who spent hours building an Estes model rocket and had that gut-check moment when sliding it onto the guide rail and getting it ready for launch. Would it go? Would it survive the trip? Or would it end up hanging from a tree branch, or lost in the high grass that always seemed to be ready to eat model rockets, planes, Frisbees, or pretty much anything that was fun?

Model rocketry was most definitely good, clean fun, even with the rotten egg stink of the propellant and the risk of failure. To mitigate those risks, the West Covina Model Rocket Society, the group the film focuses on, was formed in the 1960s. The boys and girls pictured had the distinct advantage of living in an area where many of their parents were employed by the aerospace industry, and the influence of trained engineers shows — weekly build sessions, well-organized range days, and even theodolites to track the rockets and calculate their altitude. They even test-fired rockets from miniature silos, and mimicked a Polaris missile launch by firing a model from a bucket of water. It was far more intensive and organized than the early rocketry exposure most of us got, and has the look and feel of a FIRST robotics group today.

Given the membership numbers the WCMRS boasted of in its heyday, and the fact that model rocketry was often the “gateway drug” into the hacking lifestyle, there’s a good chance that someone in the Hackaday community got their start out in that park in West Covina, or perhaps was even in the film. If you’re out there, let us know in the comments — we’d love to hear a first-hand report on what the club was like, and how it helped you get started.

Continue reading “Retrotechtacular: Junior Missile Men Of The 1960s”

Three-Stage Thrust Vectoring Model Rocket With Tiny Flight Computers

Flying a thrust-vectoring rocket can be a challenge, and even more so if you stack multiple stages and a minimalist flight computer on top of it all. But [Joe Barnard] is not one to shy away from such a challenge, so he built a three stage actively guided rocket named Shreeek.

[Joe] is well known for his thrust-vectoring rockets, some of which have came within a hair’s breadth of making a perfect powered landing. Previous rockets have used larger, more complex flight computers, but for this round, he wanted to go as small and minimalist as possible. Each stage of the rocket has its own tiny 16 x 17 mm flight computer and battery. The main components are a SAM21 microcontroller running Arduino firmware, an IMU for altitude and orientation sensing, and a FET to trigger the rocket motor igniter. It also has servo outputs for thrust vector control (TVC), and motor control output for the reaction wheel on the third stage for roll control. To keep it simple he omitted a way to log flight data, a decision he later regretted. Shreeek did not have a dedicated recovery system on any of the stages, instead relying on its light weight and high drag to land intact

None of the four launch attempts went as planned, with only the first two stages functioning correctly in the test with the best results. Thanks to the lack of recorded flight data, [Joe] had to rely on video footage alone to diagnose the problems after each launch. Even so, his experience diagnosing problems certainly proved its worth, with definitive improvements. However, we suspect that all his future flight computers will have data logging features included.

Continue reading “Three-Stage Thrust Vectoring Model Rocket With Tiny Flight Computers”

So Close To Landing A Model Rocket On Its Tail

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.

View from rocket of the ascent motor falling away immediately after being ejected

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.

Continue reading “So Close To Landing A Model Rocket On Its Tail”

Advanced Model Rocket Flight Computer Reaching For The Stars

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.

AVA’s predecessors

[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”

The Ultimate Model Rocket Launchpad

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”

Model Rocket Launcher Is So Serious, It Has A Briefcase

What could be more thrilling than launching a complex rocket that you built yourself? For starters, launching it with literally anything better than the stock ignition system would be a step in the right direction. How about a briefcase full of fantastically fun overkill?

[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.

[FastEddy59] plans to hold the first launch in a few months, and we sincerely hope he outfits the rocket with a camera.

Continue reading “Model Rocket Launcher Is So Serious, It Has A Briefcase”

Silo Launched Model Rocket Goes Thoomp

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.

Continue reading “Silo Launched Model Rocket Goes Thoomp