LVL1 has a new rocketeering group. This rocket engine testing platform is the first project to come out of the fledgling club. The purpose of the tool is to gather empirical data from model rocket engines. Having reliable numbers on thrust over time will allow the team to get their designs right before the physical build even starts.
The rig uses a pine base, with a PVC frame, threaded bolts, and a PVC cuff for mounting the engine in place. It is set to fire up in the air, directing the thrust down onto a scale. The flex sensor in the scale is monitored by an Arduino, and should be able to hold up to the 5000
pounds grams of thrust max which this type of engines can put out. The data is pushed via USB to a laptop computer where it is stored in a spreadsheet.
Calibration would be an issue here. But as long as they’re always using the same strain sensor the numbers will be accurate enough relative to each other.
When we posted our call for rocketry hacks and builds, we expected to see a few altitude sensors and maybe a GPS module or two. Apparently, we forgot similar hardware is very popular in the remote-controlled aircraft world, and can be successfully added to a rocket as [Kevin] and his ArduPilot equipped J motor rocket showed us
The ArduPilot is a small Arduino comparable board designed for UAVs, quadcopters, and other whirligigs not powered by rocket motors. To get real-time telemetry from his rocket, [Kevin] attached a GPS receiver and an XBee transmitter. When launched on an H165 motor, [Kevin] was able to keep a radio lock on his rocket, allowing him to pull down data in real-time.
There are a few drawbacks to using the ArduPilot to collect flight data; the ArduPilot only reports ground speed, a somewhat useless feature if the vehicle is going straight up. Also, there is no way for [Kevin] to record data to an SD card; the ground team must be able to receive the XBee, lest bits of data go missing. For most rockets the radio issue shouldn’t be a problem. [Kevin] launched the same hardware on a J motor and was able to receive data from 3600 AGL.
Since we put out a call for model and amateur rocketry hacks, we’ve been getting a lot of submissions on our tip line. Here’s two that found their way to us yesterday:
Upgrading an original
Back in the early 70s, Estes released a rocket with an 8mm movie camera attached to the nose of the rocket. It was called the Estes Cineroc, and is an excellent demonstration of engineering prowess to fit a movie camera inside a cardboard tube. The Cineroc is somewhat of a collector’s item, so of course there’s a reproduction kit with a payload bay large enough for [Bob Marchese]’s 808 key fob video camera. His launch video looks awesome, has color, and doesn’t need to be mailed off to Estes to be developed.
Much better than a lightbulb and a button
Remember the old yellow (or blue, and I think maybe a red one) push-button launch controller? Equipped with an arming key (a piece of wire), batteries, and a button, that controller wasn’t much to write home about. [Joe Niven] built his own launch controller with multiple LED lights, buzzer, continuity checker, and a battery tester. Not bad for a 555 and a pair of 4000-series logic chips.
Last month, the Cambridge University Spaceflight society launched two stages of their Martlet 1 three-stage rocket. After seeing our call for rocket builds, they sent in a launch report. We’re glad they did; it’s an amazing piece of work that screams into the atmosphere faster than the speed of sound.
The society is designed the three-stage Martlet 1 with the goal of reaching 15km (50,000 feet) over a launch range at Ben Armine in Scotland. This launch was a test of stage separation, intended to work out any bugs in the system before going to the full-sized rocket.
When Martlet 1 takes off, it’s 1st stage engine fires for 5 seconds and coasts for another 9 seconds. In the video after the break, the guys expected to hear the pop of the second stage igniting after 14 seconds. The team forgot to account for the fact the rocket would be 3km in the air at that time, and thanks to the slowness of sound the second stage was heard though the clouds at 25 seconds after launch.
With rockets, hardly anything goes exactly as planned, so unfortunately the team only recovered the bottom half of their rocket. After searching over 60 square km for the second stage, the guys realized it might be lost to the moors of Scotland. Hopefully the second stage will turn up soon so the full 3 stage stack can be realized.
Check out the launch videos after the break.
Continue reading “Two-stage rocket climbs to 15 km, promptly gets lost”
If you’re building model rockets you want to make sure they fly straight, and most of that is dependent on the stabilizer fins. It has long been a problem come assembly time. How can you make sure that they’re being aligned without any variation? [Rrix] mentioned that one technique is to use a square to position them perfectly perpendicular to the bench on which the rocket is being assembled. But this is still prone to error. His method uses a couple of precision jigs made out of cardboard.
He designed this pair of jigs in Inkscape, then used the files to fabricate them out on a laser cutter. It worked like a charm, but led him to another issue that can be solved in a similar way. Model rockets have rail guides that travel along a rod attached to the launch pad as the craft accelerates to a point where the fins have enough effect to keep it going in a straight line. If those guides aren’t straight, your fin alignment will be all for naught. His second version of the jigs includes a cut out for these guides.
Last April, we caught wind of a very impressive rocket engine being built by Copenhagen Suborbitals. That engine was on the test pad this weekend, and the video is incredible (skip to 20:30 for the actual test). The Copenhagen Suborbitals team pulled off a successful test firing of their 65 kilo Newton alcohol and liquid Oxygen-fueled rocket.
When last we saw the TM65 engine, it was sitting on the design floor of the Copenhagen Suborbitals workspace. The plan was to fire the engine using alcohol fuel and LOX pressurized by Helium, but that plan was changed to use Nitrogen as the pressurant. The static test was an immensely successful demonstration of the engine, but unfortunately the chamber pressure (and therefore thrust) was a little low meaning the team will be moving back to Helium for the next test.
Thanks to the very successful test of the TM65, Copenhagen Suborbitals may be launching their HEAT booster later this year possibly carrying their new space capsule. Even if it’s only a crash test dummy that will make the ride into space, we can’t wait for the video of the flight.
Check out a few more (abridged) videos of the TM65 test firing after the break.
Continue reading “Test firing the largest amateur-built liquid fuel rocket engine”
There isn’t a hacker out there that isn’t interested at least a little bit in the prospect of building a mission specific rocket to explode someone off the face of the planet… without killing them. We got a tiny taste of what is coming when they let us watch their engine test a few weeks ago. Tomorrow, May 19th, they are going to broadcast a launch live! You can watch it on their site beginning at 1:15 AM pacific. For some additional insight, you can also read the tweets of [Elon Musk], the founder of spaceX during the event.
Take a few minutes and enjoy the video below that discusses the program and some of the engineering obstacles they’ve had to overcome.
Continue reading “Reminder: SpaceX launch tomorrow. Watch it live!”