Show HN: Homemade rocketship treehouse – hardware to custom OS (rocket.jonh.net)
The Ravenna Ultra-Low-Altitude Vehicle is a backyard rocketship treehouse nestled in the Seattle neighborhood of Ravenna. Click the link to see a demo video (http://rocket.jonh.net).
The hexagonal treehouse is about 6.5 feet (2 meters) across at its widest point. The frame is welded mild steel with riveted aluminum siding. It contains nearly 800 LEDs forming dozens of numeric displays spread across 14 control panels, each with an acrylic face laser-cut and etched with labels such as "Lunar Distance" and "Hydraulic Pressure". The pilot controls the rocket using a joystick and panels full of working switches, knobs and buttons. Underneath the capsule are three "thrusters" that shoot plumes of water and compressed air under the control of the pilot's joystick, simulating real positioning thrusters. Takeoff and docking sequences are augmented by a paint-shaker that simulates the vibration of a rocket engine. Sound effects complete the illusion, with a powered subwoofer that gives the rocket a satisfying rumble.
When it was built in 2011, rocket operations were controlled by three Atmega328 microprocessors on custom-fabricated printed circuit boards, running a small operating system, RULOS, built just for this project. A trench running from the house to the rocket carries 12VDC power for the lighting and electronics, water for the thrusters, compressed air, and several data signals.
Since 2011, the two-person team has upgraded it, here is a recent update from the makers:
One of the most visible changes is replacing the primary 4-line display with a slicker 6-line display (i.e., 6 rows of 8 columns of 7-segment LEDs). The audio synthesizer has been upgraded to a PCB that can generate 50khz, 16-bit audio. The interconnection bus, which had been flat IDC cable carrying individual on/off lines, was upgraded to a true I2C-based networked distributed system with over a dozen individually addressable targets, all interconnected by standard cat5 cable that carries both our I2C protocol and power. We also moved much of the electronics from 8-bit atmega328s to newer, 32-bit STM32F3's. RULOS has been expanded into a pretty general purpose embedded systems platform ported to 5 major lines of CPU (atmega, attiny, stm32, nxp lpc, and esp32). We've used it for dozens of other projects in the last 12 years, including a nanosecond-accurate timestamper, a GPS datalogger, an air quality sensor, various little electronic control boards for toys (e.g. these, and this), and an autonomous boat (that sank). It is all available on Github: https://github.com/jelson/rulos.
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[ 5.7 ms ] story [ 99.0 ms ] threadAn observant HN user (dcminter - thanks!) ran across it the other day and suggested it as a candidate for the second-chance pool (explained at https://news.ycombinator.com/item?id=26998308). I enthusiastically agreed and we got back in touch not only with the original submitter but the project makers as well. I hope they'll comment in this thread!
I'm definitely not going to show this to my kids because I have other plans for the next three years...
Edit: I love the GPS datalogger, it's like the random number generator doing '4' all the time.
Here are some of our end users enjoying our efforts:
https://photos.app.goo.gl/8zca5kXXbAf2vcJh6
Here's disco mode, though I think this is with the old audio synthesizer:
https://photos.app.goo.gl/vkenYZKATyDRB1386
The original rocket's primary display was 4 rows of 7-segment LEDs. It was actually just 4 of our 1-row boards all stacked on top of each other. For the makeover we replaced it with a native board that had 6 rows:
https://photos.app.goo.gl/Dtiv5dN8FfrBAkDK7
Here's a video of it playing pong on my bench before installation:
https://photos.app.goo.gl/bWfQkTaF3eUyacb78
The old display boards were controlled by bit-banging latches over long parallel cables. This turns out to be a very bad idea (any EE could tell you this, but we're computer scientists). In the 2019 update we changed the remote display control from bit-banging to proper networking using I2C-based packets. We didn't want to remake every single display board, so we came up with a shortcut: we designed little snap-on "dongles" that speak the new I2C protocol and translate to bitbang commands that just go a few cm to the display board below. Here's the dongle installed on one display board:
https://photos.app.goo.gl/z9e6z6p4vXgb5j5aA
Here's a side view showing how they stack:
https://photos.app.goo.gl/tAzF4Aeq1dWVHFxE6
And here is one of the new dongles in situ with the new STM32-based primary controller, and the upgraded 32-bit audio synthesizer:
https://photos.app.goo.gl/oQxEZKRUZsK4Ry6W7
We're both pilots so of course we had to put in a Hobbs meter. The rocket has over 600 hours on it:
https://photos.app.goo.gl/ydecF3q8VkdnJB1JA
Amazing thank you. Very classy engraved cover for the boards.
And love the Pong game, it's a cool effect the way the "ball" cascades through the segments.
> Well, that logo's so classy, it needs to go on a patch! I could have had it done for maybe $80 at some web vendor. But why do that when we can spend $200 on craigslist for an old embroidery machine, and learn to do it ourselves?
> The embroidery software I used to do the patch was pretty awful. In the spirit of do-do-it-yourself-yourself, I wrote my own embroidery software for inkscape.
We actually did haul the rocket hundreds of miles to Maker Faire years ago:
https://photos.app.goo.gl/ESRsJChacRbvpqZU7
Here it is taking on hydrazine:
https://photos.app.goo.gl/1tcRasHpkVJUHq9s7
We had a line of kids waiting for "rides":
https://photos.app.goo.gl/gV9p6a8cVjWqeWgg9
Basically it did nothing, but man did it inspire my imagination. I remember spending hours playing with it as my parents talked and played cards. This must have been the late 70s as I was 4 or 5 at the time (if that tells you my age).
These kids have it good.
Jon's oldest child -- pictured on the web site as an 8-year-old -- is now a sophomore in college, majoring in engineering. I'd like to think the rocket had some small part in that, too.
That is why I made a tactile "busy box" for my nephew: https://www.youtube.com/watch?v=2BGSkwGI6BI
Just a lot of fun buttons "doing nothing" as you say. :D
Three things I learned from the play-test with the end user (my 1.5 year old nephew):
- The corners and edges are a bit sharpish. If I would do it again I would add more chamfer there. (No actual accidents though, other than that it tore the wrapping paper while in transit :))
- Having a bunch of different buttons was really good. Some were harder for him to actuate, but he kept playing with them for weeks (with interruptions of course), and eventually managed to activate all of them.
- The parents deemed the LEDs too bright and applied some tape to dim them. If I would do it again I would wire one of the many potentiometers to regulate the brightness.
I don't have the time/skill/patience for something of this scale, but I love doing little projects that make life magic for other people.
So far I have created multiple kids gaming tables.
I made a lego play table that had storage drawers underneath and stuck big baseboards on the top.
I made quite a few kids playtables using model railroad stuff like grass mats, trees, houses, roads and given them to my boy or to the kids of friends.
I've converted old radios into custom music players for friends birthdays including birthday greetings on various "radio channels".
I converted an old rotary phone into a present for mu mum where you dial a number and hear people tell you their birthday greeting.
I made an alien adventure game in the park for my 8 year old boys birthday party with a story and sound effects and treasures to find.
I created a beach adventure for my boy when he was 6 years old in which he dug up a model sailing ship in the sand which contained a treasure map and a key leading to a little wooden chest wrapped in chains and padlocked and full of costume jewellery and trinkets.
My boy is now 14 years old and the current project is to utilise his interest in robotics to convert toys to robots with the objective of raising his self esteem and making him believe he can do amazing things, give him something to show his friends because he did most of the work.
The older I get, the more I find that this is in fact all I really want to do - be a modern day Gepetto.
It doesn't take much to create magic for other people.
It was great.
I could also imagine going on tour. Like, you get permission in advance from some random park in some random city, and you just set it up with no public announcement and just see what happens. I mean, when I was a kid I'd think it was awesome if some random spaceship just suddenly was there, and then a week or so later it was gone. Even if it's clearly not a real spaceship, it'd still have been a great experience.
The aesthetic we were going for was more Apollo Guidance Computer, so 7-segment LEDs were perfect. It turned out to also be a great design choice software-wise because the entire rocket originally ran on an atmega328 which had only 2k of RAM; there really wasn't much room for frame buffers. But the state of a 7 segment digit (plus one decimal point) fits perfectly into one byte, so the entire rocket, which was originally 14 8-digit rows, needed only 112 bytes of frame buffer.
By about 2012 we wanted to write more complex software, so I made new revision of the main controller that took an atmega1284, which has a lot more RAM (16K, vs 2K) and program space (128K, vs 32K).
The big retrofit in 2019 went to a 32-bit STM32 which had a hardware floating point unit, making it possible to do fancier animations. The rocket now supports the classic "snake" game.
But still just 7-seg LEDs :)
Just.... wow.
What did the rocket mean to you growing up?
Were you the envy of all your friends at the time?
Do you remember the original trip to scout for parts? How did the plan and execution take part from your point of view & recollection?
Was the rocket always a rocket in your imagination? What else was it if not?
How about for your siblings and friends?
Any other rocket-related anecdotes?
Do you think it influenced your choice of career? Or was that just destiny?
Where, ultimately, do you want to go with your career? Genuine rocket scientist?
I'm agog. Also more than a little envious; my own father's home-built treehouse for me and my brother was little more than a plank in a tree with a rope ladder to get up to it. But that was plenty and, in my imagination, so many other things...
I don't know that envy was the right word but everyone thought it was pretty cool.
I do but only that I was really interested in the rivet guns as it was a tool I'd never seen before haha.
I'm kinda weird in that I don't have a mental eye so it wasn't like in my imagination like most people would think of it but it was definitely something that I spend a lot of time thinking about as a child.
My siblings are a lot younger than me so I don't know exactly but they definitely seem to think it's cool especially my younger brother.
I remember that when we went to maker fair with the rocket I could not be less interested in it and spend as much time as I could looking at the other displays because well I had the rocket at home.
I don't think the rocket specifically influenced my carrier choice but I got to participate in lot of projects like this with my dad for all of my childhood and so that definitely is a big reason I'm in college for mechanical engineering right now.
As a mechanical engineering major I really would love to go into robotics especially like conveniency things like home automation systems.
It definitely was one of those things that was just around when I was a kid and as I started on my own projects I look back at that project as my first.
Regardless, awesome work.
On a more serious note, what an incredible project. There's all the very obvious stuff -- the creativity, the learning experience, the sense of wonder and ways it can inspire both the adults and kids -- but above all what sticks out to me is the amount of time that it took to put this together could have so easily... gone to waste? Like, what a nice way to have a hobby, spend time with your kids, and have something to show for it at the end? I worry that with the increased ease with which you can just "doom scroll," things like this are tougher and tougher to achieve. I remember as a child I'd get bored so I'd be FORCED to get my toys out and make up stories. In a similar vein, as an adult, this is such a positive outlet for "free time," but I worry that the attention economy has made committing to projects like these even harder (at the margin).
I applaud the rocket scientist (and astronaut!). Truly inspiring stuff!
I'm about wasted after a day of work and in/outdoor house chores.
https://en.wikipedia.org/wiki/The_Rocket_(short_story)
BTW If you kids are interested in space, consider trying some model rocketry. I bought my son an Estes kit some years back, one thing led to another and he is now competing in a UK national model rocketry championship (UKROC) and planning to do a degree in aerospace and astronautics.