Wish me luck
sylvie369
Posts: 1,622
Weather permitting, I'm going to fly my XBee-MAWD pull-pin telemetry device later today, in a high power rocket, using a Prop Protoboard with a 4x20 LCD as the receiver. I just finished the altimeter bay this morning (keeping up the rocketeers' tradition of doing things at the last moment before a launch), and everything works fine in ground testing. The hardest part was probably putting together a connector from the altimeter to my custom pc board, as the altimeter end uses one of those tiny Molex Picoblade connectors.
This is my first real project using·a Prop programmed to do things in parallel, as I have one cog receiving altitude data, one cog receiving pull-pin status, and one cog continually updating the LCD based on the state of a buffer that the first two cogs write to. I got a lot of good help with this on the forum - thanks. It's also my first real project using a pc board of my own design, one that I made up in Eagle and had produced at BatchPCB.
If I don't destroy the rocket on that flight, I'll put up my GPS tracker transmitter on a second flight of the same rocket. There's no Prop on that project yet - I'm just sending the rocket's position to a terminal program on my laptop on the ground. I've been working on a program for the Prop to parse the received GPS data for display, but I wasn't able to finish that program in time for this launch. Hopefully over the summer, again assuming I don't destroy it all today.
This is my first real project using·a Prop programmed to do things in parallel, as I have one cog receiving altitude data, one cog receiving pull-pin status, and one cog continually updating the LCD based on the state of a buffer that the first two cogs write to. I got a lot of good help with this on the forum - thanks. It's also my first real project using a pc board of my own design, one that I made up in Eagle and had produced at BatchPCB.
If I don't destroy the rocket on that flight, I'll put up my GPS tracker transmitter on a second flight of the same rocket. There's no Prop on that project yet - I'm just sending the rocket's position to a terminal program on my laptop on the ground. I've been working on a program for the Prop to parse the received GPS data for display, but I wasn't able to finish that program in time for this launch. Hopefully over the summer, again assuming I don't destroy it all today.
Comments
Ray
Dave
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Whit+
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Timothy D. Swieter, E.I.
www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" 16:9 LCD Composite video display, eProto for SunSPOT, PropNET, PolkaDOT-51
www.tdswieter.com
I flew the fancy telemetry thing on an I285, and the electronics worked perfectly. Unfortunately, the main parachute got jammed up and didn't come out, so I crashed, destroying the upper tube and the electronics bay. The electronics themselves are fine - I'll just have to get a few more tubes, redrill the holes, reinstall the wiring, and so on.
I started getting altitude data right on schedule, and called out altitudes into the PA system. It reported a peak altitude of 2001 feet (which is just perfect in my book...), and then right on cue, the flight status indicator on the telemetry readout went to "Descending", and then the indicator for the apogee event went on, right as the drogue charge on the
rocket blew. I called out altitudes on the way down, and right at 500 feet, the indicator for the main parachute event went on, the main blew, and about 20 seconds later, I landed, at which point the "flight status" indicator changed to "Landed". Since I didn't watch the rocket itself at all, I didn't know I'd crashed until I got out to where it had landed.
So I have somewhat mixed feelings. That was a lot of work to have to do over again before the next launch, but I can build a slightly better version now that I'm practiced and have some time, and none of the expensive stuff was damaged. And everything worked properly! This was easily the most sophisticated piece of electronics I've seen in any of our rockets, and it
all worked as planned.
I used a Celestron "Power Tank" as the power supply for the receiver,·with a cigarette lighter - 7.5V converter·going from one of the lighter ports on the Power·Tank to the power connection on the Prop Protoboard.·That worked just fine, and was pretty convenient.
I'll rebuild the electronics bay soon, and hopefully have a good version of everything to show off at·the Prop Expo near Chicago in a month and·a half.
Paul
Post Edited (sylvie369) : 3/28/2010 12:48:52 AM GMT
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Timothy D. Swieter, E.I.
www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" 16:9 LCD Composite video display, eProto for SunSPOT, PropNET, PolkaDOT-51
www.tdswieter.com
Today I used a Pro 38 4 grain I 285 motor. It's about a foot long, 38mm in diameter, made up of Ammonium Perchlorate Composite Propellant. Later I flew the rocket on a 5-grain J375 - essentially·25% more motor. We fly much larger things than this. This rocket weighs about 8 pounds empty (that is, before the motor is installed). I've seen rockets weighing 10-20 times that much fly at our field. Our largest motors are 4" in diameter and about 4 feet long. The largest I've flown was a K motor about 2" in diameter and 14" long, easily lifting a 16 pound rocket to 3800 feet.
This setup does just send the data directly from the altimeter and pull-pins to the XBee, without an intervening computer. There's no reason why there couldn't be an onboard Propeller, though, and I assume I'll do that sometime in the next year or two. But it's always better to keep as much hardware on the ground as possible. If I can do it without an onboard computer, I will.
Post Edited (sylvie369) : 3/28/2010 2:56:46 AM GMT
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Timothy D. Swieter, E.I.
www.brilldea.com - Prop Blade, LED Painter, RGB LEDs, 3.0" 16:9 LCD Composite video display, eProto for SunSPOT, PropNET, PolkaDOT-51
www.tdswieter.com
You also could add a 20-30 G 3-axis accelerometer to the mix. If watching Sparkfun's trebuchetted pumpkin's acceleration data was instructive, imagine what forces are generated by one of your 5 grain liftoffs will look like!
I'm working on getting computers to fire ejection charges. I've got a MOSFET circuit breadboarded here, design taken from a commercial altimeter, which works fine. I don't understand the continuity check part yet, though, and that's important. We generally don't fly unless something beeps on the pad to tell us that our charges are going to fire.
It's not that difficult to get a rocket to exceed 20Gs on liftoff - I supervised·a Level 1 certification flight yesterday by a guy who used a "VMax" H400 motor that probably put him over 20Gs. I've managed to surface mount a Freescale MMA6255AEG 50G two-axis accelerometer onto a DIP adapter board without screwing it up, and I'd go with something like that, maybe paired with a 20G one (though as soon as you have two measures of the same variable, you wind up not knowing that variable's value - in common English, the man with two watches never knows what time it is).
Attached are a couple of photos of rockets of the kind of size I'm talking about. The colorful one is 4" in diameter, something a little over 6 feet tall, about 6 pounds, and about the size of what I used for these telemetry flights. The other photo is one of my largest rockets, 5.5" in diameter, 8 feet tall, about 15 pounds, and flew on a K550 motor (about 90 Estes D motors) to about 3000 feet carrying a wireless remote control for parachute deployment. My group won a $500 "Best non-engineering group" prize for that project from the NASA Space Grant Consortium.
looking at your rocket project and at the balloon-enabled cameras launched some months ago I was wondering if a rocket could be lifted by some balloons and the ignited when at some km of the surface, using large balloons... Is it possible ? feasible ?
ps: I think this is really cool.
thanks !
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Visit some of my articles at Propeller Wiki:
MATH on the propeller propeller.wikispaces.com/MATH
pPropQL: propeller.wikispaces.com/pPropQL
pPropQL020: propeller.wikispaces.com/pPropQL020
OMU for the pPropQL/020 propeller.wikispaces.com/OMU
pPropellerSim - A propeller simulator for ASM development sourceforge.net/projects/ppropellersim
Good luck
Very cool
Graham
It was too windy for me to fly rockets today, but I did ground test my XBee GPS transmitter. It seems to work fairly well. I turned on the transmitter, connected an XBee through the Parallax USB board to my netbook, opened a terminal window and turned on data capture to file. I also carried my handheld Garmin unit, and took a little walk around the park, down into a ravine, and through some woods, to see how well the XBee Pro on my transmitter stayed in contact with the one on the netbook sitting on the trunk of my car back at the range head.
One problem I'm going to have to get to is that my netbook goes to sleep after a while, and so stopped receiving before I'd gotten back to the car to turn it off. The file was fine, though. You can see in the third image below the track from my transmitter in magenta (red, whatever...) superimposed on the track from my Garmin handheld in blue (cyan?). It tracks pretty well, except a bit in the lower left corner, where I walked down into a ravine and was no longer even close to line-of-sight to my car, which was .27 miles away. I'm pretty confident that if I were to carry the receiver with me I'd be able to stay in better contact. More importantly, after I lose contact, I was easily picking it up again when I did get up on a little hill in the extreme lower left corner. It's almost inevitable that you're going to lose contact: regaining contact gracefully is what really matters.
I should have gone further back into the woods, but there were dog trainers with live ammunition back there, and I wasn't wild about getting too far away from the runway.
Post Edited (sylvie369) : 3/28/2010 10:31:13 PM GMT
I wonder, has anyone attached a camera to the rocket? cgi.ebay.com/2GB-Spy-Car-Key-Chain-Camera-DVR-Webcam-Video-Recorder_W0QQitemZ290419297473QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item439e56ccc1
I stuck one on a model helicopter and flew around my house www.youtube.com/watch?v=igs_P5cyvls They are very light and while the vibration would make for a shaky video going up, I reckon you would get some nice footage on the way down.
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www.smarthome.viviti.com/propeller
There are several rocket videos on YouTube.· There used to be a YouTube group called the rocketry stage, but YouTube has changed during the past year, and I don't know if that group exists any more.
There are many aerial photos, and a few videos posted at the Flickr group at http://www.flickr.com/groups/rap/ .
Dave
As Dave said, lots of rocketeers have onboard video. We took a nice video the weekend before last using a small USB camera from Boostervision. Generally you get far better video on the way up, as long as you keep the spinning to a minimum (by attaching your fins squarely), because coming down under parachute causes a lot of vibration. In addition, it's hard to get the camera to point at anything other than sky and parachute as it shakes around like that. On the way up, though, it's easy to just have it pointed down along the body tube. That's what almost everyone does, though I've seen some pointed out more sideways.
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Visit some of my articles at Propeller Wiki:
MATH on the propeller propeller.wikispaces.com/MATH
pPropQL: propeller.wikispaces.com/pPropQL
pPropQL020: propeller.wikispaces.com/pPropQL020
OMU for the pPropQL/020 propeller.wikispaces.com/OMU
pPropellerSim - A propeller simulator for ASM development sourceforge.net/projects/ppropellersim