highaltitude.log.20060630

[00:00] <jcoxon> i wasn't suggesting we grab some balloons a climbing frame and a rocket :-p
[00:00] <jcoxon> but yeah
[00:00] <jcoxon> with careful preparation
[00:00] <defy> grab some model rockets and hope they go in the right direction ;P
[00:01] <rocketboy> it could be done - and actually that is where I came from when I started lookig at balloon flights 3 - 4 years ago
[00:01] <jcoxon> rocketboy, what would you say is the hard part?
[00:01] <jcoxon> the balloons or hte rocket?
[00:02] <rocketboy> it would be kind of neat just to launch a model from a baloon platform - just for the fun
[00:02] <jcoxon> :-d
[00:02] <defy> hehe
[00:03] <rocketboy> the hard part is finding a few hundred square miles of nothing
[00:03] <rocketboy> ;-)
[00:03] <rocketboy> technically the active stabilization
[00:03] <defy> thats my biggest problem, few hundred square miles doesnt even exist in nz
[00:04] <jcoxon> how about the sea
[00:04] <jcoxon> there was a reason the first rockoons were launched from the boats
[00:05] <rocketboy> even with the sea you have to get out of airspace (upper airspace is the problem) - that extends about 300 miles out to sea I think
[00:05] <jcoxon> on a side note here is my favourite balloon story
[00:05] <jcoxon> http://www.atmosp.physics.utoronto.ca/MANTRA/MANTRA_98-00_pages/press.html
[00:05] <defy> "This was a suborbital launch. In order to reach orbit, it is necessary to achieve a speed of Mach 25"
[00:05] <defy> wow
[00:06] <jcoxon> 8km/s
[00:06] <jcoxon> thats approximate escape velocity
[00:07] <rocketboy> also you have to follow a particular path which again means a guidence system
[00:08] <rocketboy> for example you cant launch an orbital satellite from a gun without it carrying its own propulsion
[00:09] <jcoxon> hmmm
[00:09] <defy> weren't people talking about using rail guns to launch stuff into space at one stage?
[00:09] <jcoxon> there was an project using guns
[00:09] <rocketboy> getting into orbit is several orders of magnitude more difficult that getting into "space"
[00:10] <jcoxon> one step at a time :-)
[00:11] <jcoxon> so 100,000ft being 30.5km
[00:12] <jcoxon> with 4xKCL3000
[00:12] <rocketboy> yep you can launch it into space but you need somthing else to get it into orbit - if its launched from a gun it will either take a path that escapes - or returns to earth - cant remember what the proof is for this but it was reasonably convincing (to me anyway)
[00:12] <jcoxon> now it sounds sensible
[00:12] <jcoxon> no*
[00:14] <rocketboy> yes 4 x 3Kg lift shoud to it (Carbon fibre frame).
[00:14] <macfreak4> to orbit you don't just have to be going fast, but at the right angle
[00:14] <macfreak4> so you "fall" around the earth
[00:14] <macfreak4> instead of into it
[00:14] <rocketboy> yes I think thats why you can do it from a gun alone
[00:14] <jcoxon> http://www.kaymont.com/pages/sounding-balloons.cfm
[00:17] <rocketboy> if the rocket carrys a stabilization system then actually a single (big) ballon would probably do - fire the motor up and steer round (or through) the balloon.
[00:18] <rocketboy> the rocket aint going to worry about a woosy balloon
[00:18] <jcoxon> that system is tested
[00:18] <jcoxon> a large drawing pin will do
[00:19] <defy> hehe
[00:19] <rocketboy> 2 true
[00:19] <macfreak4> what? launch a rocket around an object?
[00:19] <macfreak4> how does that work?
[00:19] <defy> you wouldnt want it to get hooked to the rocket though would you?
[00:19] <macfreak4> i think at least three balloons are in order
[00:19] <macfreak4> and since the load is split between all the balloons, each one can be smaller
[00:20] <jcoxon> http://en.wikipedia.org/wiki/James_Van_Allen
[00:20] <jcoxon> http://en.wikipedia.org/wiki/Rockoon
[00:21] <rocketboy> suspend the rocket 50ft under the baloon, cut the cord, fire the motor and the guidence system does the rest
[00:22] <rocketboy> by the way I have a couple of KCI800s in a (dark and cool) draw at work
[00:22] <jcoxon> oooo
[00:22] <jcoxon> yeah i've managed to wreck my 200s
[00:22] <jcoxon> not sure they are usuable
[00:23] <defy> hrm, the legal 900mhz radios im still looking at will do 20 miles, i wonder if thats enough
[00:23] <jcoxon> i've got a rather funny looking 500 as well (well its not the normal colour
[00:23] <jcoxon> )
[00:23] <rocketboy> how did you wreck them
[00:23] <defy> the illegal ones do 40, heh
[00:23] <jcoxon> not dark and cool enough
[00:23] <rocketboy> for how long?
[00:24] <rocketboy> mine are about 3 years old
[00:24] <macfreak4> uhh
[00:24] <macfreak4> oh
[00:24] <macfreak4> you have to keep them dark and cool?
[00:24] <macfreak4> :/
[00:24] <macfreak4> oops
[00:25] <jcoxon> macfreak4, basically they change colour
[00:25] <jcoxon> slightly degrade
[00:25] <rocketboy> and preferably airtight
[00:25] <defy> what are you guys talking about?
[00:25] <jcoxon> balloons
[00:25] <defy> ah okay
[00:25] <macfreak4> how long can they be light and somewhat warm?
[00:25] <jcoxon> rocketboy, i think it was because i kept opening the draw
[00:25] <jcoxon> macfreak4, no idea
[00:26] <jcoxon> apart from the neck they should be uniform colour
[00:26] <defy> I'm pretty sure im not going to rely on my 45c ebay balloon so it might become a pool toy for a day
[00:26] <rocketboy> I really need to fly mine before they get too old (I think 5 years is about the limit)
[00:27] <macfreak4> ok
[00:27] <macfreak4> i just threw mine in the basement
[00:27] <macfreak4> the coldest, darkest place in the house
[00:27] <macfreak4> :P
[00:27] <rocketboy> should be OK then
[00:28] <jcoxon> rocketboy, well i reckon in the near future we can find time to fly them
[00:28] <jcoxon> with a small payload they could get quite high!
[00:28] <rocketboy> excellent
[00:29] <rocketboy> I read that 150Kft was possible with under inflated balloons
[00:29] <jcoxon> yeah it should be - just
[00:29] <jcoxon> really need perfect conditions
[00:29] <jcoxon> would be rather impressive
[00:30] <rocketboy> anyway - have to go now - need sleep
[00:30] <rocketboy> CU
[00:30] <jcoxon> bye rocketboy
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[00:35] <defy> i2c is multi device yeah?
[00:35] <jcoxon> i think so
[00:35] <jcoxon> i've never used it
[00:36] <defy> ah ok, i'm thinking of using the i2c for temperature sensors
[00:36] <defy> not too sure how its suppose to be wired with multiple devices though, i guess just daisy chained
[00:36] <jcoxon> i think you use a adc that has multiple inputs
[00:37] <defy> ah well if i can find a temp sensor with a voltage output that would work too
[00:37] <defy> i still have plenty of adc ports available
[00:38] <defy> gpsboomerang.com guy just emailed me back, i asked him if he sells his airframes seperately, he said they'll sell them for $70, not too bad
[00:38] <jcoxon> not bad at all
[00:38] <defy> yea, especially considering its a proven to work airframe
[00:38] <jcoxon> true
[00:38] <jcoxon> but
[00:41] <icez> uhm how does it navigate without a motor?:/
[00:41] <jcoxon> right i'm off to bed
[00:41] <jcoxon> cya all
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[00:41] <defy> icez you drop it from a balloon and it flys back home
[00:41] <defy> idealy
[00:42] <icez> eh
[00:46] <icez> 25 miles away yeah
[00:46] <icez> :P
[00:51] <defy> well the idea is to not let it go in a jetstream or anything, lol
[00:52] <defy> plenty of people are doing it, you just cant let it go on hugely windy days, the gpsboomerang guy has done over 200 drops
[00:52] <defy> and only lost 2 planes
[00:53] <icez> cool
[00:53] <icez> so it doesn't really fly to a place
[00:53] <icez> it just glides and hopes to be around the point
[00:53] <icez> :P
[00:53] <defy> well yea, you'd have the nav computer know where the point of no return is
[00:53] <defy> and if it reaches that point before droping, to drop early
[00:54] <defy> it has gps and an autopilot so it knows where to fly to
[00:55] <icez> yeah but it can't move right?
[00:55] <defy> it can steer
[00:55] <defy> it just cant propel it's self
[00:55] <defy> but thats what gravity is for :P
[00:56] <icez> steer?!
[00:56] <icez> how:P
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[00:56] <icez> i don't see any moving parts:/
[00:56] <defy> flight computer and servos
[00:56] <defy> on what?
[00:56] <defy> the gpsboomerang?
[00:57] <defy> it definately has moving parts :P
[00:57] <defy> what pictures are you looking at?
[00:57] <icez> uhm
[00:57] <icez> the ones on his website
[00:58] <icez> on the newspaper
[00:58] <icez> :/
[00:58] <defy> http://www.gpsboomerang.com/images/gallery/Launch.jpg you can kind of see the rudder in this picture
[00:58] <icez> ohhh
[00:58] <icez> *gets it*
[00:59] <defy> but yea, it definately at least has rudder and elevator movement
[00:59] <icez> so it's cool then
[00:59] <icez> you can put your stuff inside his belly
[00:59] <defy> yup
[00:59] <defy> he sells full units
[00:59] <defy> with all the hardware inside
[01:00] <defy> but i just want his airframe, hehe
[01:01] <icez> no fun if it's already done
[01:01] <icez> :)
[01:01] <defy> hehe yea exactly
[01:02] <defy> and i've only spent about 1000 bucks on all my hardware, his planes cost a LOT more
[01:02] <icez> !!!
[01:02] <icez> that's a lot of stuff to throw into space
[01:02] <icez> :P
[01:02] <icez> stuff=money*
[01:03] <icez> well
[01:03] <icez> not as much as NASA..but still:p
[01:03] <defy> haha yea
[01:03] <defy> unfortunately its not the most expensive hobby i have
[01:03] <icez> i need something really tiny that can fit inside a rocket
[01:03] <icez> oh, really, what is it?
[01:03] <icez> :P
[01:04] <defy> well, had...when i was info nitro rc cars about 2 years back i could easily spend 500 bucks on parts and not blink and eye
[01:04] <defy> such a waste
[01:04] <icez> aww
[01:04] <icez> i made a CO2 powered car in school once
[01:04] <icez> i lost the race but so what
[01:04] <icez> :P
[01:04] <defy> hehe we did that too
[01:05] <icez> the one that won the guy's car broke into 5 pieces
[01:05] <icez> haha
[01:05] <defy> with an arm that comes down and pops the co2 canister?
[01:05] <icez> i don't remember that part
[01:05] <icez> we had a fishline guiding it
[01:05] <defy> ah
[01:05] <defy> ours were really just rockets with wheels
[01:05] <defy> yea, and fishline
[01:05] <defy> hehe
[01:05] <icez> i should try it with a estes rocket:D
[01:05] <icez> lol
[01:06] <defy> the guy that won ours made the his car SO thin
[01:06] <icez> a tiny A one:p
[01:06] <icez> yeah
[01:06] <icez> mine had the wheels inside
[01:06] <defy> hehe
[01:08] <icez> are gumstixs really small and light? (with the GPStix)
[01:08] <icez> :/
[01:08] <defy> I'd weight it for you but its all screwed into its box at the moment
[01:08] <icez> haha
[01:08] <defy> but yea, they are pretty small...
[01:08] <defy> the gpsstix makes the board combo a little wider
[01:09] <defy> so you'd need probably a 1 1/2 inch diameter rocket to fit it inside
[01:09] <icez> oh then no problem
[01:09] <icez> it'll be about 6+ inch
[01:09] <defy> wow thats a thick rocket, how tall?
[01:09] <icez> not that tall
[01:09] <icez> i don't know yet:P
[01:09] <icez> can't find a working cad program for linux:(
[01:10] <defy> ick, yea linux as a desktop is horrid :P
[01:10] <icez> but i'm planning to have 2 stages of 3 "rockets" each
[01:11] <icez> and the second stage will be ignited by whatever I put inside and then the burst will pop the parachute
[01:11] <defy> cool
[01:12] <defy> so you want to trigger the second stage with a computer?
[01:13] <icez> yeah
[01:13] <defy> sweet
[01:13] <icez> and take in gps/altitude information
[01:13] <icez> but gps can wait
[01:13] <icez> (it'll go straight most of the way so:P)
[01:13] <defy> hehe
[01:14] <icez> uhm
[01:14] <icez> i can't find the gpstix
[01:14] <icez> :/
[01:15] <defy> gumstix.com > products > expansion
[01:15] <defy> looks like they are still out of stock
[01:15] <defy> they said they would get new stock in about 6-7 weeks...about 6-7 weeks ago
[01:16] <icez> :/
[01:16] <icez> expansion as in expensive too
[01:16] <icez> what's the audio port for?
[01:16] <icez> :P
[01:17] <defy> audio :P
[01:17] <defy> not sure why they chose to combine the gps and audio board exactly
[01:17] <icez> oh well
[01:18] <defy> but the gpsstix has audio, and lcd/touchscreen pinout
[01:18] <defy> i think they were aiming for people wanting to make their own handheld gps units or something
[01:18] <icez> i can always record birds
[01:18] <icez> ;p
[01:18] <defy> lol
[01:18] <icez> oh right
[01:18] <defy> depending on how heavy speakers are and how loud i can get them, i might use the sound on the gpsstix for a warning/audio locater
[01:19] <defy> if crashing = true start making lots of noise!
[01:19] <icez> lol
[01:21] <icez> thumbstix *sigh*
[01:22] <defy> if you're going to get a gumstix
[01:22] <defy> make sure you also get a waysmall board
[01:22] <defy> so you have some way of consoling the gumstix
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[01:23] <defy> oops
[01:23] <icez> basix is good?
[01:24] <defy> I have 2 connex
[01:24] <defy> not sure what the difference is with the basix? maybe just that is has bluetooth?
[01:25] <defy> ah it has bluetooth and mmc, but a lot of the expansion boards only work with the connex
[01:25] <defy> so you have to make sure you get the right boards that will fit together
[01:25] <icez> yeah
[01:25] <icez> and...does gps get altitude, or only location?
[01:25] <icez> :P
[01:25] <defy> yup altitude
[01:26] <icez> cool
[01:26] <defy> it does everything a normal gps does...its a ublox gps module
[01:26] <icez> even cooler
[01:26] <defy> http://www.gumstix.org/tikiwiki/tiki-view_faq.php?faqId=18 < some info about the gpsstix
[01:27] <defy> also if you can, get the xm versions
[01:27] <defy> the normal buildroot just hovers on 3mb
[01:27] <defy> so it doesnt leave you much space for anything else
[01:28] <defy> but 16mb gives you much more room
[01:28] <icez> it does connect to the basix:D
[01:28] <defy> sweet
[01:28] <icez> yuppies
[01:28] <defy> also if you're looking at the gpsstix and planning on using an active antenna, be reading to do some hacking
[01:28] <defy> s/hacking/soldering
[01:28] <icez> lol
[01:29] <defy> reading=ready, lol...my brain and hands don't wont to work together today
[01:29] <defy> too much redbull and not enough sleep i think
[01:29] <icez> i'm going to test my rocket first
[01:29] <icez> with one stage
[01:29] <defy> sweet
[01:29] <icez> make sure it stays alive a few times:]
[01:29] <icez> the problem is
[01:29] <icez> if the gumstix doesn't launch the second stage in mid air
[01:29] <icez> the parachute wont open
[01:29] <icez> :/
[01:30] <defy> hrm, yea you might want some secondary chute deployment, or design it so it doesnt rely on the computer as much
[01:30] <defy> how does the gumstix know when to fire? a timer?
[01:30] <icez> yeah
[01:31] <defy> true, im sure you could do that with much simpler electronics
[01:31] <icez> i can get pretty fair approximations of how long it takes for the rocket to stop
[01:31] <defy> but im no electronics person so i couldn't tell you how :P
[01:31] <icez> well
[01:31] <icez> i'm not either:P
[01:31] <defy> hehe
[01:31] <icez> oh what about the battery
[01:31] <defy> yea the batteries are the biggest part of it all
[01:32] <defy> but rockets dont stay up long, so you shouldnt need a big one
[01:32] <defy> im using 6 x AA 2300mAh rechargables
[01:32] <defy> and that gives me about 10 or so hours of run time
[01:33] <icez> wow
[01:33] <icez> i'm going to need some bigger rockets:p
[01:34] <defy> lol
[01:34] <defy> 6inch diameter sounds huge
[01:34] <icez> well
[01:34] <icez> yeah
[01:34] <icez> it does have 3 rockets per stage:|
[01:34] <defy> and if you're running it less than an hour you could probably get away with some very small batteries
[01:35] <icez> yeah
[01:35] <icez> it'll probably be less than 2-3 minutes
[01:35] <icez> :P
[01:36] <defy> hehe
[01:36] <defy> 2 slim cell phone batteries would probably do it
[01:37] <icez> crap! we had a mountain full of those at my school
[01:37] <icez> :/
[01:37] <icez> like...huge..
[01:37] <icez> impossibly huge
[01:37] <defy> lith-ion batteries?
[01:37] <icez> well i don't know:/
[01:37] <defy> hehe
[01:37] <icez> cellphone batteries:P
[01:37] <defy> if i used the same batteries my cell phone uses
[01:38] <defy> I'd need 4 of them to get the same compacity, and they would weigh 1/4th the weight of my normall AA cell's
[01:38] <defy> but charging them is a bitch
[01:38] <icez> :/
[01:38] <defy> and they're about $50 each, lol
[01:39] <icez> well i'll get power
[01:39] <icez> :P
[01:39] <icez> *puts a PC PSU*
[01:39] <defy> you should join the gumstix users mailing list if you want to get a feel for what other people are doing with them, and what kinds of problems people run into with them
[01:39] <icez> yeah
[01:55] <defy> gpsboomerang guy just emailed me back
[01:55] <defy> aparently the only control they use is rudder
[01:55] <icez> again
[01:55] <icez> ok
[01:55] <defy> and they treat it more as a parachute than a glider
[01:55] <defy> thats pretty interesting, i would have thought it would at least need horizontal stability
[01:56] <defy> i guess the glider takes care of that
[01:57] <icez> thats cool
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[04:48] <macfreak4> heya
[05:35] <defy> hey
[06:58] <icez> rawr
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[09:00] <jcoxon> morning all
[09:00] <jcoxon> defy, that rotate log script is great
[09:00] <jcoxon> i left it running for the last 8 hours
[09:00] <jcoxon> and its literally taken up no space
[09:02] <defy> yea text files get nice compression :D
[09:07] <jcoxon> right so gps is now working nicely
[09:07] <jcoxon> now to sort out the phone part :-D
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[21:12] <rocketboy> jcoxon
[21:12] <rocketboy> u there
[21:12] <rocketboy> ?
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[21:15] <jcoxon> yup
[21:15] <jcoxon> i'm here
[21:15] <jcoxon> sorry was watching nasa tv
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[21:16] <rocketboy> I'm just finishing the TX - and I was trying to work out how it will mount in PIII
[21:16] <rocketboy> will you cut a hole in the styrofoam - or should I put it in its own insulation
[21:16] <jcoxon> http://www.flickr.com/photos/29158271@N00/171517460/in/pool-highaltitude/
[21:17] <jcoxon> it'll sit next to the radio modem
[21:17] <rocketboy> ok in the botton left corner
[21:17] <rocketboy> ?
[21:18] <jcoxon> yup
[21:18] <jcoxon> is that enough space?
[21:18] <jcoxon> do you want some measurements?
[21:18] <rocketboy> the antenna needs to come out the bottom - is it OK to cut a small (3mm) hole for the antenna wire to come through
[21:18] <jcoxon> yup
[21:18] <jcoxon> fine
[21:19] <rocketboy> o yes lots of space - the unit is only about 15mm dia x 50mm long
[21:19] Action: jcoxon likes the fact that Pegasus has a payload bay
[21:20] Action: jcoxon volunteers to transport supplies to the ISS
[21:20] <jcoxon> how long is the antenna?
[21:20] <rocketboy> the antenna is going to look like this http://images.google.co.uk/imgres?imgurl=http://www.radio-electronics.com/info/antennas/quarter_wave_vert/radial_system.gif&imgrefurl=http://www.radio-electronics.com/info/antennas/quarter_wave_vert/quarter_wave_vertical.php&h=253&w=350&sz=2&hl=en&start=7&tbnid=9NmCpGXaUIBAJM:&tbnh=83&tbnw=116&prev=/images%3Fq%3Dground%2Bplane%2Bvertical%26svnum%3D10%26hl%3Den%26lr%3D%26safe%3Doff%26client%3Dfirefox-a%26rls%3Dorg.
[21:20] <jcoxon> on the bottom of the payload some impact form will be added
[21:20] <rocketboy> wow hang on
[21:21] <rocketboy> try a shorter link
[21:21] <rocketboy> http://www.radio-electronics.com/info/antennas/quarter_wave_vert/radial_system.gif
[21:21] <jcoxon> how long is that?
[21:21] <jcoxon> is it rigid?
[21:22] <rocketboy> only upside down - ie. the radials will attach to the underside of PIII and the vertical will pount down - get the idea?
[21:22] <rocketboy> not very rigid (to save weight) - its just made of thin co-ax cut to length
[21:23] <jcoxon> so if it sticks directly out the bottom
[21:23] <jcoxon> on landing what will happen?
[21:23] <rocketboy> the co-ax brading is going to be made into the radials
[21:23] <jcoxon> oh right
[21:23] <rocketboy> humm yes - its going to get squished
[21:24] <jcoxon> i assume it has to point downwards
[21:24] <rocketboy> don't see ther is much I can do about that - the antenna has to be that way to get the best ouput in flight
[21:24] <jcoxon> right
[21:24] <rocketboy> yes has to to get ouput in the right direction
[21:24] <jcoxon> okay well i'll work around it
[21:25] <jcoxon> it'll be fine
[21:25] <jcoxon> as long as it squishes as the payload really has to land upright
[21:25] <jcoxon> to make sure we get a gps lock
[21:25] <jcoxon> (though i reckon the parachute will then pull it over)
[21:26] <rocketboy> no prob -its just very thin flexible wire
[21:26] <rocketboy> how thick is the botton styrafoam
[21:27] <jcoxon> hmmm at present:
[21:28] <jcoxon> 35mm
[21:28] Nick change: malgar2 -> malgar
[21:28] <jcoxon> but some more padding will be added on the bottom
[21:29] <rocketboy> ah - do you know how much?
[21:30] <rocketboy> I need to cut the co-ax to more or less the right length - so the radials will push through the hole and then lie flat against the bottom
[21:30] <jcoxon> hmmm i don't
[21:30] <jcoxon> basically the nova guys will cover me with their insurance if i have some padding on the base
[21:32] <rocketboy> humm - thinks .....
[21:33] <jcoxon> i can't imagine its any more then 2cm
[21:33] <jcoxon> i could raise the module itself
[21:33] <jcoxon> if the cable is to long
[21:33] <jcoxon> there is lots of space
[21:33] <jcoxon> and i could quite easily make a bit of space in the lid
[21:37] <rocketboy> ok - ideally id like the antenna in the centre anyway - could the hole be put in the top right of the area with the radio modem - then i can loop the wire over
[21:38] <jcoxon> yup
[21:38] <jcoxon> no problem
[21:38] <rocketboy> what are the dimensions - width and height
[21:39] <jcoxon> of the payload bay?
[21:39] <rocketboy> yes - the radials are about 17cm long (i.e. 34cm across) - which would probably be corner to corner
[21:40] <rocketboy> ?
[21:40] <jcoxon> the base of Peg III is 16cm x 25cm
[21:41] <jcoxon> its a little larger then
[21:42] <jcoxon> thats no problem
[21:42] <jcoxon> i'll make hte additional padding larger
[21:42] <jcoxon> then it'll float better :-D
[21:42] <rocketboy> no not too much (I make that 29cm corner to corner)
[21:42] <jcoxon> yeah
[21:42] <jcoxon> but its a rectangle reember
[21:42] <jcoxon> while you are looking at a square of the antenna
[21:43] <rocketboy> yes - actually a 25cm square would be ideal
[21:44] <rocketboy> of foam on the bottom - then the radials will go corner to corner
[21:44] <jcoxon> yeah
[21:44] <jcoxon> it'll also act as a brake
[21:44] <jcoxon> add to slowing the descent
[21:45] <rocketboy> sounds ok - I'll think some more
[21:46] <jcoxon> hmmm i need to find some nichrome wire
[21:46] <jcoxon> where would sell it?
[21:47] <rocketboy> got some
[21:47] <jcoxon> ooo maplin stock it
[21:48] <rocketboy> how yes thats wher I got it
[21:48] <rocketboy> Ideal for cutting styrafoam
[21:49] <rocketboy> or cut down devices (although I prefer my own idea)
[21:49] <jcoxon> :-D
[21:49] <jcoxon> i'm building my cutdown tomorrow
[21:49] <jcoxon> really don't like them
[21:49] <jcoxon> but gotta have one
[21:50] <rocketboy> use my cutdown - just needs a burst of about 3V
[21:50] <jcoxon> how much of an explosion is it?
[21:51] <jcoxon> what would be left?
[21:51] <rocketboy> its a small igniter (used in rocketry) in a plastic tube - fire the igniter - the tube shatters
[21:51] <jcoxon> the gumstix could easily provide 3.3v
[21:51] <rocketboy> minute
[21:51] <jcoxon> the plan was to have the cutdown below the parachute
[21:52] <jcoxon> acting as the knot that holds the parachute up
[21:52] <jcoxon> so when it "cuts"
[21:52] <rocketboy> - it really needs a power FET to drive it - its certainly a lot less than a nicrome cutdown
[21:52] <rocketboy> did you get my picture of it
[21:52] <rocketboy> ?
[21:52] <jcoxon> it releases the balloon and allows the parachute to open
[21:52] <jcoxon> yeah i did
[21:54] <rocketboy> just connect one end of the tube to the baloon, the other end (the end with the wires) to the payload
[21:54] <rocketboy> put a 1 sec pulse through it and it will release the baloon
[21:55] <rocketboy> it makes a small pop really
[21:55] <jcoxon> would a gumstix gpio do?
[21:55] <rocketboy> not what you would call an explosion
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[21:55] <jcoxon> or should i isolate it
[21:55] <phatmonkey> hii all
[21:55] <jcoxon> hey phatmonkey
[21:55] <rocketboy> - i tested quite a few of them
[21:56] <rocketboy> hi phatm
[21:56] <jcoxon> rocketboy, it saves me messing around with nichrome
[21:56] <jcoxon> if one is avaliable
[21:57] <jcoxon> i might add a manual switch between the gumstix and the cutdown
[21:57] <rocketboy> I have a couple made up - are you thinking of PIII or PIV
[21:57] <jcoxon> PIII
[21:57] <jcoxon> (PIV will be in africa :-D )
[21:57] <rocketboy> ok - can put in with TX
[21:57] <rocketboy> oh yeh forgot
[21:58] <rocketboy> you need somthing that is capable of switching about 3 to 4 amps - like a power FET
[21:58] <phatmonkey> i *desperately* need a gps antenna - where do you all get them?
[21:59] <rocketboy> just wire that to the gumstix port
[21:59] <jcoxon> phatmonkey, ebay
[21:59] <phatmonkey> i can't find anything on ebay, argh
[21:59] <phatmonkey> they're all selling them for cars and things, with monster cases and cables
[21:59] <phatmonkey> ... and i dunno about cutting antenna cables
[22:00] <rocketboy> actually crownhill associate in cambridge do quite a good cheap one (I have one on my GPS system)
[22:01] <rocketboy> alternativly I have a GPS QFH antenna from a radiosone you can have (free)
[22:01] <phatmonkey> i just need a really small and light one with a short (1ft?) cable
[22:01] <phatmonkey> ooh, what plug?
[22:01] <rocketboy> no plug - have to wire up
[22:02] <phatmonkey> hmm
[22:02] <phatmonkey> where did you get yours on ebay?
[22:02] <rocketboy> http://www.crownhill.co.uk/product.php?prod=1475 - have to gouge out the rather heavy magnet they put in it.
[22:03] <rocketboy> no someone gave me it
[22:03] <phatmonkey> thanks
[22:03] <phatmonkey> jcoxon?
[22:03] <phatmonkey> hmm, wonder what connector they have on that
[22:04] <jcoxon> my antenna is from ebay
[22:04] <phatmonkey> ah, datasheet
[22:04] <rocketboy> no connector its just wire ended.
[22:04] <phatmonkey> hmm, don't want an active one either
[22:04] <jcoxon> rocketboy, you'll have to bear with me - i'm awful with electronics
[22:05] <jcoxon> so i'll use a power FET to turn on a circuit
[22:05] <jcoxon> which wil cause the cutdown to activate?
[22:05] <rocketboy> they sell it to go with this - which actually hasn't got rf connecter - just pins
[22:05] <jcoxon> or will the gumstix directly drive the FET and therefore the cutdown?
[22:06] <rocketboy> the gumstix turns on the FET (these need about 3V to turn on) - and the FET is used to fire the igniter
[22:07] <rocketboy> I'll draw a circuit
[22:07] <phatmonkey> hahaha - http://cgi.ebay.co.uk/BMW-GPS-ANTENNA-M3-M5-TYPE-AERIAL-DUMMY-STYLE-WHITE_W0QQitemZ250003123328QQihZ015QQcategoryZ36676QQrdZ1QQcmdZViewItem
[22:08] <phatmonkey> ggrrrr, maybe i should just get a normal one
[22:08] <phatmonkey> rip off the case and magnet and snip the cable
[22:09] <jcoxon> all my cable is tidied away in the lid
[22:09] <jcoxon> couldn't be bothered to cut it
[22:10] <phatmonkey> i don't see me being able to connect aerial cable back together
[22:10] <phatmonkey> been through all 9 pages for "gps antenna" on ebay - there's nothing
[22:10] <phatmonkey> sigh. i'll look through ebay.com
[22:12] <phatmonkey> i don't really want to get a gps with a built in antenna because i'll have to put it out of the insulation
[22:12] <phatmonkey> and i can't risk killing the gps
[22:15] <rocketboy> just sending a circuit pic
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[22:29] <phatmonkey> yays, my gumstix goodies have arrived in the uk
[22:29] <phatmonkey> guess they should be here tomorrow morning
[22:36] <phatmonkey> ach, this is silly
[22:36] <phatmonkey> maybe i should just get a cheap one and see what i can do
[22:39] <macfreak4> ?
[22:39] <macfreak4> cheap what?
[22:39] <phatmonkey> gps antennas
[22:39] <macfreak4> oh
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[22:44] <phatmonkey> http://cgi.ebay.co.uk/GPS-Antenna-Aerial-MCX-Road-Angel-2-Holux-Navman-Garmin_W0QQitemZ330001296543QQihZ014QQcategoryZ75327QQrdZ1QQcmdZViewItem
[22:44] <phatmonkey> could just get that and see if i can rip it apart
[22:44] <phatmonkey> hnnngg
[22:44] <phatmonkey> wonder if i can snip the cable
[22:45] <phatmonkey> might be able to disconnect it at the antenna end i suppse
[22:46] <jcoxon> bbl
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[00:00] --- Sat Jul 1 2006