[00:00] <edmoore> so what's the command to make a bridge?
[00:00] <Randomskk> a bridge?
[00:00] <edmoore> i.e to wrap my current svn w/c with gittiness
[00:01] <Randomskk> git-svn, but it will need to fetch it from the main svn server
[00:01] <edmoore> oh, I have to start again?
[00:01] <Randomskk> i.e. git-svn clone svn://whatever/svn/
[00:01] <Randomskk> it fetches, I'm guessing, every revision rather then just the current latest copy
[00:02] <EI5GTB> evening
[00:02] <Randomskk> in other words it can't take a current svn working directory and turn it into a git repository, but it can make a new local git repository out of a remote svn server
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[00:03] <Randomskk> and that local git repo will act as a normal svn repo to the server - e.g. for me, cusf's svn is a git repo, I can commit, rebase, merge, etc etc as normal, then when I commit to the server it goes out as an svn commit
[00:03] <Randomskk> hi EI5GTB
[00:03] Action: EI5GTB has just wiped the last windows pc in the building :D no more windows :D
[00:03] <EI5GTB> well, there are windows, but no microsoft!
[00:03] <Randomskk> huzzah
[00:08] <Randomskk> edmoore: okay, now running a duplicity backup of the svn
[00:08] <edmoore> git-svn didn't make it through macports
[00:08] <edmoore> this is annoying
[00:08] <Randomskk> once the first big backup is made, all future ones are incremental, just making small changes
[00:08] <Randomskk> edmoore: it may be an additional package
[00:08] <Randomskk> it is on ubuntu
[00:09] <edmoore> oh I know, but it still isn't coming across. there are plenty of places that tell you how to get it, it's just they seem to be lying
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[00:16] <Randomskk> backup complete
[00:16] <Randomskk> that's just to my server, but duplicity will just as happily put it on s3 and do the same incremental deal which is neat.
[00:16] <edmoore> ah, git-svn not in path but git svn (minus hyphen) works
[00:16] <edmoore> always the little things
[00:16] <Randomskk> oh, right, yea.
[00:17] <Randomskk> with incremental changes the total monthly s3 bill would be something like $1.50 or so, assuming daily backups and no massive changes
[00:17] <edmoore> this is pretty
[00:17] <edmoore> ok, I reckon that's money well spent probably but stick it round t'email list
[00:18] <Randomskk> will do. if we do get the nas that might be easier still, though offsite backup is always nice
[00:18] <edmoore> this would be offsite for some value of site
[00:18] <Randomskk> I suppose it's offsite from srcf
[00:18] <Randomskk> (in a room full of who knows what, otoh :P)
[00:19] <edmoore> I can run a similar nas in college room to backup CUSF
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[00:20] <Randomskk> I just `duplicity ./svn scp://adam@randomskk.net//home/adam/cusf_svn_backup` and ta-da
[00:22] <Randomskk> can we run cron jobs on pip?
[00:22] <Randomskk> clearly yes
[00:23] Action: Randomskk should rtffaqs or such
[00:26] <edmoore> Randomskk: once I have the clone, do i need to do git svn commit or just git commit?
[00:27] <Randomskk> I believe you can "git commit" for local commits and then "git dcommit" to commit up to the main svn, but one sec
[00:28] <Randomskk> looks like it may well be "git svn dcommit" to commit up to svn
[00:28] <edmoore> dcommit - a bit arbitrary!
[00:29] <Randomskk> http://orestis.gr/blog/2008/08/23/git-svn-tutorial/ might be informative
[00:37] <Randomskk> and 'git rebase --interactive', especially specifying remotes/trunk, lets you squash your many local commits into one commit to go to svn
[00:37] <Randomskk> there may be a nicer way to do that, too.
[00:37] <edmoore> indeed - that looks very useful
[00:38] <Randomskk> it's also super useful to rearrange commits, or move various chunks of code changes around between commits
[00:38] <edmoore> gitx seems good
[00:38] <Randomskk> like sometimes I am working on one file, then suddenly swap to another file and make a little change there, then finish up on the first file and commit
[00:38] <Randomskk> but now my commit has two separate things in
[00:38] <Randomskk> rebase lets you squash, separate, recommit, etc etc to get everything nice
[00:39] <Randomskk> (obviously the real solution is to commit twice, as you can tell git what changes to commit every time you run commit)
[00:39] <Randomskk> (i.e.: git add file1.c; git commit -m "did some stuff to file1"; git add file2.c; git commit -m "a little thing in file2"
[00:39] <Randomskk> that works equally to changes within the file, you can commit individual little changes together
[00:42] <edmoore> oh, a note on svn backups
[00:43] <edmoore> it's playing with fire to just copy the folder
[00:43] <Randomskk> ugh, figured it might be. like mysql.
[00:43] <edmoore> as you can do that mid-commit and break absolutely everything
[00:43] <Randomskk> yea.
[00:43] <edmoore> so there's a command like svn hot-copy or something
[00:43] <Randomskk> svnadmin dump apparently works
[00:44] <Randomskk> http://wiki.archlinux.org/index.php/Subversion_backup_and_restore loads of weird and arcane commands
[00:44] <Randomskk> but equally yes, "svnadmin hotcopy" apparently works
[00:45] <Randomskk> apparently svnadmin dump doesn't include repo control files, in fact, while svnadmin hotcopy literally just makes a safe copy of the current directory that can be copied elsewhere and used in situ
[00:47] <Randomskk> c.f. git: "git clone" creates an identical copy of the repo, over ssh, git, http, ftp, local file, etc
[00:48] <Randomskk> and you can even push/pull changes to/from that new copy
[00:48] <Randomskk> :P
[00:48] <Randomskk> can the ic7000 run on batteries? usefully, anyway?
[00:54] <edmoore> Randomskk: oh very much so
[00:54] <edmoore> it's still pretty portable
[00:54] <Randomskk> yup, thought it looked pretty portable but the icom site just specifies some random dc input from a mains psu
[00:54] <edmoore> 13.8V
[00:55] <edmoore> i.e. a 12V battery freshly charged
[00:55] <Randomskk> fair enough
[00:55] <Randomskk> SLA or similar?
[00:55] <edmoore> perfect
[00:55] <edmoore> you want deep cycle SLAs
[00:55] <edmoore> Hawker Drycell or something
[00:56] <Randomskk> vs the ft817's "I can run off AA batteries!"
[00:56] <edmoore> yes - though the 817 is actually quite famous for how badly it runs off AAs
[00:56] <edmoore> it's a bit of an in-joke
[00:56] <Randomskk> hehe
[00:56] <Randomskk> and it takes 8 of them at a time
[00:56] <edmoore> yeah
[00:56] <edmoore> right, I might hit the sack
[00:57] <Randomskk> yup, I probably should
[00:57] <edmoore> early start for more pcb design
[00:57] <Randomskk> eng in soc lecture at 9 and all that
[00:57] <edmoore> i just remembered gvim is availble for windows
[00:57] <Randomskk> might bring my laptop along and work on something useful :P
[00:57] <edmoore> that goes on first thing tomorrow
[00:57] <Randomskk> heh
[00:57] <Randomskk> best part of gvim is I can use zenburn as my colour scheme
[00:57] <edmoore> :)
[00:58] <edmoore> i think i'm on space cadet
[00:58] <edmoore> Cobalt, apparently
[00:58] <Randomskk> I have Kate set to zenburn on linux, but straight vim on its default "dark background" one
[00:58] <Randomskk> which works well enough but zenburn is nicer, I need to use gvim more
[00:58] <Randomskk> anyway yup sleep time, seeya :P
[01:00] <Randomskk> btw you replied to me rather than the list
[01:00] <Randomskk> I think?
[01:01] <edmoore> quite so
[01:02] <Randomskk> yay peltiers also shipped
[01:02] <Randomskk> in a few days: ice
[01:02] <edmoore> happy ice cubes
[01:02] <edmoore> right, definitely off now
[01:02] <Randomskk> in a few days: cold enough outside to scrape ice off the road
[01:02] <Randomskk> night
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[09:04] <MikeMc> morning
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[09:11] <rjharrison_> Morning all
[09:11] <rjharrison_> Hi MikeMc
[09:11] <rjharrison_> Talk went well last night
[09:11] <MikeMc> cool
[09:11] <rjharrison_> There may be more HABers on here soon
[09:12] <juxta> where did you speak, rjharrison?
[09:20] <rjharrison_> At Old Broadcasting House in Leeds
[09:20] <rjharrison_> There is a copy of the slides here http://www.robertharrison.org/svn/filedetails.php?repname=the-icarus-project&path=%2Ftalks%2F2009-11-09+wylug%2FThe+Icarus+Project.pdf
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[09:51] <juxta> will check it out, cheers rjharrison
[09:54] <rjharrison_> Dual balloons at launch
[09:54] <rjharrison_> http://www.robertharrison.org/images/icarus2/Launch5/two-balloons.jpg
[09:55] <juxta> nice :D
[09:55] <juxta> rather different string configurations though
[10:04] Laurenceb (n=laurence@hosts-137-205-164-135.phys.warwick.ac.uk) joined #highaltitude.
[10:04] <Laurenceb> hi
[10:07] <juxta> hi Laurenceb
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[10:30] <juxta> has anybody used an ICOM IC-490A? there's one for sale quite cheaply here, and whilst I don't need another radio, it might come in handy :)
[10:33] <rjharrison_> juxta good point on the sring configuations
[10:33] <rjharrison_> I have this theory on the rule of thirds for burst balloons
[10:34] <rjharrison_> Basically 2/3rds of the way along the string put the para and then the balloon at the end
[10:34] <juxta> one third below the chute, 2 thirds above? or 2 thirds below chute & one above?
[10:34] <rjharrison_> 2/3 above payload
[10:34] <juxta> ah right
[10:35] <juxta> to keep the remains of a shredded balloon away from the chute and prevent tangling?
[10:35] <rjharrison_> This keeps the balloon and para well away from the payload and makes for a cleaner return journey
[10:35] <rjharrison_> Yep
[10:35] <juxta> :)
[10:35] <juxta> where do you put your cutdown? just above the chute?
[10:35] <rjharrison_> Now if you are using pyro cutdown then you want the para
[10:35] <rjharrison_> hehe yep you're ahead of me
[10:35] <juxta> what exactly is pyro cutdown, if I can ask?
[10:36] <juxta> an explosive?
[10:36] <rjharrison_> acrillic tube and gun powder
[10:36] <rjharrison_> One sec
[10:37] <rjharrison_> juxta http://www.flickr.com/photos/30721501@N05/sets/72157619368022480/
[10:37] <rjharrison_> Pyro construction
[10:37] <juxta> very nice!
[10:38] <juxta> hmm - do you need some kind of license for the black powder?
[10:39] <rjharrison_> No smokeless powder is fine
[10:39] <rjharrison_> http://www.flickr.com/photos/30721501@N05/
[10:39] <rjharrison_> This is one exploding
[10:39] <juxta> wow, awesome
[10:39] <rjharrison_> Assuming you want to get a max alt on your first few balloons forget pyro
[10:39] <Laurenceb> nice
[10:40] <Laurenceb> thats useful, what camera?
[10:40] <rjharrison_> Just go with burst
[10:40] <juxta> yeah - I'm not even sure you can buy powder of any form here
[10:40] <rjharrison_> Casio EX-F1
[10:40] <rjharrison_> 1200 frams per second
[10:40] <juxta> I made a few cutdowns which seemed to work OK
[10:41] <Laurenceb> juxta: I use resistor cutdowns
[10:41] <juxta> essentially using a resistor to melt hot glue and seperate 2 strings
[10:41] <juxta> yeah, I think maybe Laurenceb or SpeedEvil suggested it to me :)
[10:41] <Laurenceb> but I'm sure you can buy smokeless powder
[10:41] <Laurenceb> I used resistors as I trust it more
[10:42] <Laurenceb> you know its going to work as you can test the hardware in all circumstances
[10:42] <Laurenceb> pyro is single use only
[10:42] <juxta> I wasn't sure there would be enough oxygen at altitude for a proper burn of the powder - or does powder supply its own oxidising agent?
[10:42] <rjharrison_> juxta this is alot better video of pyro http://www.robertharrison.org/images/cutdown/icarus-pyro.wmv
[10:43] <SpeedEvil> juxta: burns on its own
[10:43] <SpeedEvil> juxta: no atmosphere needed
[10:43] <rjharrison_> juxta, It seesm to work just fine in practice. There is some oxidising agent in there
[10:43] <juxta> makes sense :)
[10:43] <SpeedEvil> there is all the oxidiser needed
[10:43] <russss> atmosphere optional
[10:43] <SpeedEvil> to burn ~1g of powder would take ~18g of air, or 18l
[10:43] <juxta> that's a nifty video rjharrison_ :D
[10:44] <Laurenceb> thats a lot of power
[10:44] <SpeedEvil> So the amount of air in a normal firearm is essentially negligable
[10:44] <juxta> SpeedEvil: good point
[10:44] <juxta> not to mention that 18g of air at 30km is probably more like 400L
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[10:45] <rjharrison_> juxta, I like that video too
[10:45] <juxta> how do you trigger them rjharrison_? GPIO driving a big transistor so some sort of ignition resistor in the powder?
[10:45] <juxta> to* some sort..
[10:46] <rjharrison_> edmoore designed the circuit in wiki but basically a cap and GPIO into mosfet
[10:46] <rjharrison_> mostfet acts as switch
[10:46] <juxta> nice, I'll have a look on the wiki
[10:47] <juxta> any idea of the page name?
[10:48] <Laurenceb> oh thats another reason I use resistor cutters - you dont need a large cap
[10:48] <juxta> yeah - just let it go slowly
[10:48] <Laurenceb> 1/8Watt 10ohm resistors take about 500mA
[10:48] <Laurenceb> for about 8 seconds
[10:48] <edmoore> I think steve might have designed that circuit
[10:49] <rjharrison_> juxta http://ukhas.org.uk/ideas:flight_support?s=cutdown
[10:49] <juxta> I used 1watt resistors, hehe
[10:49] <edmoore> but it's trivial with one of the logic-level mosfets
[10:49] <juxta> that's quite a large cap :)
[10:49] <Laurenceb> juxta: thats going to take some power
[10:50] <rjharrison_> It works fine without the cap any how as tested last night
[10:50] <Laurenceb> ah right... but reliably?
[10:50] <rjharrison_> but the cap is a good idea for -50C performance
[10:50] <juxta> Laurenceb: why - 1watt is just the rated power dissipation of the resistor before failure, right?
[10:50] <Laurenceb> yes
[10:51] <Laurenceb> so you need about 30Watts
[10:51] <juxta> hmm?
[10:52] <Laurenceb> well actually its going to be not quite as bad for large resistors
[10:52] <juxta> using a 1/8watt or 1watt resistor shouldn't matter in terms of power use, so long as the resistance is the same, right?
[10:52] <Laurenceb> but you need many times the rated power
[10:52] <Laurenceb> no, 1Watt wont get as hot
[10:52] <juxta> sure it will, it can just dissipate more heat
[10:53] <juxta> if you jam it inside a blob of hot glue, it'll dissipate the same amount of heat to the glue
[10:53] <Laurenceb> ...
[10:53] <juxta> it might have a lower surface temperature, because it has more surface area, but the heat produced is the same...
[10:53] <Laurenceb> yes
[10:53] <Laurenceb> its inevitably going to take more power
[10:54] <juxta> hmm. when I tested with 1/4watt 10ohm resistors at 5v or so, they would fail and smoke very fast
[10:55] <juxta> hence the move to the larger ones
[10:55] <juxta> what voltage do you use?
[10:55] <Laurenceb> 5v
[10:56] <juxta> hmm. to be honest, I haven't tested with battery power
[10:56] <Laurenceb> were you sure it was 5v ?
[10:56] <juxta> yeah
[10:56] <juxta> but my bench supply is capable of delivering 30a at 5v
[10:56] <juxta> AA's might only be capable of a few hundred ma
[10:56] <Laurenceb> and it has a voltage readout?
[10:57] <juxta> not a readout, just different settings
[10:57] <Laurenceb> you can get a few amps easily from lithium AA cells
[10:57] <Laurenceb> ah
[10:58] <Laurenceb> some power supplies giver out more - or have some ripple
[10:58] <Laurenceb> I had that same issue with my wall supply, I discovered it was closer to 6V
[10:58] <juxta> hmm
[10:58] <Laurenceb> you have to consider V^2/R
[10:59] <Laurenceb> when I tried with a better regulated supply I found 5V through 1/8watt was fine
[10:59] <Laurenceb> and thats what I use
[10:59] <juxta> do they fail?
[10:59] <juxta> (as in quickly)
[10:59] <Laurenceb> its worked 6/6 times
[11:00] <juxta> ah no I meant do they sort of fizzle and burn
[11:00] <Laurenceb> nope they last fine in the bracket/pcb attachment
[11:00] <Laurenceb> that acts like a bit of a heatsink
[11:00] <Laurenceb> 5V reaches about 250C surface temperature
[11:00] <juxta> fair enough, I'll give it another crack :)
[11:00] <Laurenceb> singes the paint nothing else
[11:00] <juxta> haha - how'd you measure the temp?
[11:01] <Laurenceb> I was going to cut nylon, but decided it wasnt hot enough
[11:01] <Laurenceb> what plastics it would melt
[11:01] <juxta> ah
[11:01] <Laurenceb> so I use insulation of cheap wire, think its PE
[11:01] <juxta> cleevr
[11:01] <juxta> sort of wrap it around the resistor?
[11:01] <Laurenceb> yes
[11:02] <Laurenceb> its in a pcb with M3 boltholes
[11:02] <Laurenceb> then a 5mm hole with the resistor through the middle
[11:02] <juxta> don't suppose you have a pic? I'm interested :)
[11:02] <Laurenceb> theres a photo of a prototype
[11:03] <juxta> sure :D
[11:03] <Laurenceb> http://ukhas.org.uk/_media/projects:mihab:p6290015.jpg
[11:03] <juxta> ah, nice
[11:04] <Laurenceb> Im now using FR4 with two M3 bolts for attatching the payload, and added some brass tube as a guide for the line to the balloon
[11:04] <juxta> so basically your hand is holding the wire insulation which loops around and goes to the balloon?
[11:04] <Laurenceb> that acts as stress relaif if it hits turbulence
[11:04] <juxta> good idea
[11:04] <Laurenceb> not all the way
[11:04] <juxta> yeah, just a short run
[11:05] <Laurenceb> just to the center of the tube, then its tied to nylon line
[11:05] <juxta> the laws here say the tether for the payload must be capable of holding a load ten times the mass of the payload
[11:05] <juxta> I believe
[11:06] <Laurenceb> if the tether is that strong between the payload and a chute it should be ok
[11:06] <juxta> yeah, I figured that's where it'd take the most strain
[11:08] <Laurenceb> its good to have a weak link somewhere
[11:08] <Laurenceb> so if theres really bad turbulence you know what breaks
[11:08] <juxta> good point
[11:09] <juxta> has anybody had a chute fail/get tangled that you know of?
[11:09] <juxta> (get tangled badly enough to be pretty much useless)
[11:52] <rjharrison_> juxta regularly
[11:52] <rjharrison_> But that rule of thirds has cured that
[11:52] <juxta> so xaben the other day broke the rule? ;p
[11:53] <rjharrison_> Ahh I see
[11:53] <rjharrison_> Well cutdown needs to work :)
[11:53] <juxta> oh thats right, xaben was cutdown
[11:54] <rjharrison_> If not you will risk a tangle if the balloon comes back with everything
[11:54] <rjharrison_> ie does not burst away
[11:54] <rjharrison_> I would ignore cutdown for your fist launch
[11:54] <rjharrison_> first
[11:55] <rjharrison_> Just go with the rule of thirds. The is alot of room in OZ
[11:55] <rjharrison_> there
[11:55] <juxta> i was planning on having a resistor cutdown, but not using it on altitude, only if I get blown near water, or population
[11:57] <rjharrison_> Oh ok
[11:57] <rjharrison_> Sounds good
[11:57] <rjharrison_> Personally I wouldn't bother just wait for the right wind
[11:58] <juxta> fair enough :)
[11:58] <rjharrison_> There is alot of code to test / write to get the payload to cutdown on those conditions unless you are planning on tx'ing to the payload
[11:59] <rjharrison_> And telling it to cutdown ... also adding complexity
[11:59] <Laurenceb> its not too hard
[12:00] <Laurenceb> you can use a polygon
[12:00] <Laurenceb> and determine if the landing spot is inside or outside
[12:00] <juxta> shouldnt even need to use a polygon, I'm situated such that I'll have a latitude and a longitude bound
[12:01] <juxta> but yeah, the code testing thing is a big one, don't want it to go wrong mid flight
[12:02] <Laurenceb> test the code for cutdown triggering on a pc
[12:03] <juxta> I had a question about antenna's also - on the balloon, do most people just use a ~16cm wire with the NTX2's?
[12:08] <rjharrison_> Yep
[12:08] <rjharrison_> A simple 1/4 wave ground plane would do
[12:28] <rjharrison_> Anyone know hte 800mhz freq and power that's available?
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[12:42] <rjharrison_> hi steve
[12:56] <juxta> sorry rjharrison_ - what is meant by a ground plane exactly? I don't know much about antennas :)
[12:59] <edmoore> my favourite ever quote from doug ellison: "I thought I'd put together a public-friendly site to talk about what the whole of the UKHAS community does", "Words banned from the site. "forward error correction", "bandwidth", "ground plane" "
[13:00] <edmoore> juxta: do you know what a dipole is?
[13:00] <juxta> edmoore: yeah
[13:01] <edmoore> ok
[13:01] <edmoore> so if you replace one of the 1/4 wave verticals with a 'ground plane' - which can be a bunch of wires sticking radially out which are tied to ground, then that has the effect of mirroring what the other 1/4 wave element is doing
[13:02] <juxta> so an antenna + a suitable ground plane will yield a higher gain?
[13:03] <edmoore> well, i think the same gain as a dipole, but in a more conventiant form factor
[13:03] <edmoore> so you can stick one to the underside of a balloon
[13:03] <edmoore> let me see if I can find a pic
[13:03] <juxta> cheers edmoore :)
[13:04] <juxta> when you said a dipole, I figured you meant as in a non-antenna specific dipole, as in +/- separation, but I think I follow :)
[13:04] <edmoore> http://www.flickr.com/photos/cuspaceflight/3740244093/sizes/l/in/set-72157621752955158/
[13:04] <edmoore> so you see a 1/4 wave bit of tube sticking out of the bottom
[13:04] <edmoore> and then 4 sticking out the side at 90 degrees to each other
[13:04] <juxta> yep
[13:04] <edmoore> the ones sticking out to the side are the 'radials' - that's the ground plane
[13:05] <juxta> ah right :)
[13:05] <juxta> so basically they're just tied to the RF ground
[13:05] <edmoore> http://en.wikipedia.org/wiki/Dipole_antenna
[13:05] <edmoore> yes
[13:06] <juxta> and I take it the foam cubes on the end are just to hopefully stop the antennas from killing anybody? :)
[13:06] <edmoore> and it has the effect of illuminating a nice slightly downward facing cone with RF
[13:06] <edmoore> which is just what you want
[13:06] <juxta> (ie, no special functionality)
[13:06] <edmoore> you're not wasting energy transmitting into space
[13:06] <juxta> good point
[13:07] <edmoore> yes - we use soft things for antennas now
[13:07] <edmoore> normal wire held stiff by a drinking straw, say
[13:07] <juxta> ah righto
[13:08] <gordonjcp> how well would a turnstile work on the bottom of the payload?
[13:08] <edmoore> or some piano wire - flexible but will spring back to its correct shape
[13:09] <juxta> good ideas :D
[13:12] <edmoore> you can also make up things very quickly, like end-fire dipoles
[13:12] <edmoore> you just need a bit of co-ax for that
[13:12] <edmoore> or slim-jims
[13:12] <juxta> end-fire dipoles?
[13:12] <edmoore> or 'big wheels'
[13:12] <edmoore> lots of good antenna designs exist
[13:12] <edmoore> probably easier to google
[13:12] <juxta> will check them out
[13:16] <juxta> thanks for your advice edmoore :)
[13:16] <edmoore> no probs
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[13:16] <edmoore> FYI, we've used 1/4 wave ground=planes and end-fire dipoles before
[13:17] <edmoore> in flight
[13:17] <edmoore> would like to try a bigwheel at some point
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[14:14] Action: Laurenceb is thinking about optical depth measurement
[14:14] <Laurenceb> http://uk.farnell.com/silonex/sld-70-c2a/photodiode/dp/1219007 looks useful
[14:16] <SpeedEvil> http://www.virtualhud.com/virtualhud/VirtualHUD.aspx
[14:16] <SpeedEvil> _clever_
[14:16] <SpeedEvil> possibly, yes.,
[14:17] <Laurenceb> nice
[14:17] <Laurenceb> I was thinking of a seperate osc/lock in amp
[14:18] <SpeedEvil> Pointless
[14:18] <Laurenceb> but maybe simpler to stick the led on an io pin and have an op amp from the diode to an ADC pin
[14:18] <SpeedEvil> you turn the LED on, you measure, you turn it off, you measure. Repeat a thousand times
[14:18] <Laurenceb> on the flight computer board
[14:18] <Laurenceb> yes
[14:30] <Laurenceb> http://uk.farnell.com/optek/op251/led-ir-1206-inner-clr/dp/1678543 use that for the emitter
[14:31] <Laurenceb> then have a vertical pipe at the side of the main tank
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[15:19] <rjharrison_> What is the relation ship between visibility and distance in a fluid. I doubt it's linear?
[15:20] <Laurenceb> exponential
[15:20] <rjharrison_> Is that easy to calibrate?
[15:21] <Laurenceb> y=exp(x);
[15:21] <rjharrison_> I guess so but the last 10mil wont be measuable i guess
[15:21] <rjharrison_> soory about the poor typibg
[15:21] <rjharrison_> ing
[15:21] <Laurenceb> lol
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[15:27] <rjharrison_> Hi edmoore
[15:27] <edmoore> hi rjharrison_
[15:27] <edmoore> how's it going? how did the talk go?
[15:31] <rjharrison_> edmoore the talk went very well
[15:31] <rjharrison_> and was well recieved
[15:31] <rjharrison_> Had a bit of a surprise with the pyto
[15:31] <rjharrison_> pyro
[15:32] <rjharrison_> I tested in the office but forgot to seal the container and a bit of smoke escaped
[15:32] <rjharrison_> Other than that it was uneventfull
[15:32] <rjharrison_> So I made sure I sealed the lid in the conference room
[15:32] <rjharrison_> do as not to set the smoke detector off
[15:33] <rjharrison_> any how as you can imagine the sealed container then when off with an almighty bang scaring the crap out of me and the audiance
[15:33] <Laurenceb> heh
[15:34] <rjharrison_> the lid hit the roof the audiance steped back and a nice ball of smoke hit the sensor
[15:34] <rjharrison_> thankfully it didn't trigge
[15:34] <rjharrison_> r
[15:35] <rjharrison_> Oddly enough a fire engine hurtled by, horns a blearing, about 30 seconds after the bang. I made some quip about a quick response
[15:36] <rjharrison_> edmoore any thoughts on a date yet?
[15:36] <edmoore> am just emailing bursar precisely right now
[15:36] <rjharrison_> Cool :)
[15:36] <rjharrison_> Thakns
[15:37] <edmoore> http://www.churchillconferences.co.uk/tariff.htm
[15:37] <rjharrison_> I know its another thing to have to do
[15:37] <edmoore> which is obviously not what we have in mind to pay (would like to pay nothing) so it does somewhat depends on when the facilities are free
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[15:38] <rjharrison_> Thats cool though Jock Colville Hall for 165 for the day?
[15:40] <Laurenceb> http://www.newscientist.com/article/dn14718 <- interesting
[15:41] <rjharrison_> edmoore the WOLFSON HALL would be most cool though :)
[15:42] <edmoore> rjharrison_: I have asked for wolfdon
[15:42] <edmoore> it's a much better space
[15:43] <edmoore> wolfson*
[15:43] <edmoore> and we can have a formal dinner in t'evening
[15:44] <rjharrison_> Wow cool
[15:44] <edmoore> so were we thinking perhaps a saturday of talks and workshops, big dinner saturday night, and maybe see if we can do launching on the Sunday?
[15:44] <rjharrison_> Sounds like a plan
[15:45] <rjharrison_> Do we just pay per head for the dinner
[15:45] <edmoore> i think it might be a case of pay for yourself, yep
[15:45] <rjharrison_> Perhaps get a small fee ahead of schedule for commitment
[15:46] <rjharrison_> A notional 5 or 10 pounds per ticket
[15:46] <edmoore> to give you an idea, formall hall for us (4 courses, silver service) is about £9
[15:46] <edmoore> obviously i can't promise it'll be those rates for something more like a conference
[15:46] <edmoore> but it's a bit of a steel for students
[15:46] <edmoore> you just turn up with suit and a bottle
[15:47] <rjharrison_> Sure NP, I'm thinking about issueing some tickets and selling for a 5/10 pounds as this will give a better idea on numbers
[15:47] <edmoore> rjharrison_: I was thinking - we are getting a lot of emails from teachers at the moment asking for help with balloon missions
[15:47] <rjharrison_> Cool
[15:47] <edmoore> maybe some kind of beginner workshop that would sort them out?
[15:48] <edmoore> basically it's tough for us to individually help each one - we just don't have the time
[15:48] <rjharrison_> I'm doing one at local private school
[15:48] <rjharrison_> Where daughter is
[15:48] <edmoore> we're basically saying a blanket no except for 'mates'. Otherwise it'd be one a week
[15:48] <rjharrison_> So a beginners workshop too
[15:49] <edmoore> yeah - arduino tracker, learn how to receive ssb, learn about the DL, launch and track
[15:49] <edmoore> arduino tracker can just bit GPS->Arduino->pot-devider->Radiometrix
[15:49] <edmoore> just be*
[15:49] <rjharrison_> This is the sort of thing I had in mind any how. I would like to think that novices could come along and leave with a good idea of what involved.
[15:50] <rjharrison_> Costs, Equipment, Legals etc...
[15:50] <bt42> why do you think i have been lurking here
[15:50] <edmoore> :)
[15:50] <edmoore> hi bt42
[15:50] Action: bt42 soaks up more infos
[15:50] <bt42> hi :D
[15:50] <rjharrison_> bt42 does that sound good for you then
[15:51] <rjharrison_> Would such an event interest you
[15:51] <edmoore> so yes, i guess the whole thing would serve that purpose, maybe with some more techy talks sprinkled in
[15:51] <bt42> not atm, i am too broke to think about anything like this seriously
[15:51] <bt42> but i found this place from diydrones
[15:51] <rjharrison_> Yep about hobble etc and where teams are going
[15:51] <edmoore> bt42 - awesome
[15:51] <edmoore> where abouts from DIYdrones?
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[15:52] <rjharrison_> Right I have a meeting to attend
[15:52] <rjharrison_> Look forward to getting the date fixed and then I'll get some flyers out
[15:52] <rjharrison_> bbiab
[15:52] Action: Laurenceb is also interested
[15:52] <Laurenceb> - in drones
[15:54] <bittwist> i wish diydrones had a channel like this, they could use a similar type of gathering place
[15:54] <bittwist> right now is blogs, slow, not that great for convo
[15:54] <bittwist> and that web chat
[15:54] <Laurenceb> they have some serious stuff with the dspic board
[15:54] <bittwist> with is rapid, but short sessions
[15:54] <bittwist> no hardcore lurking :D
[15:54] <Laurenceb> i'd get one if I was convinved by the pitot tube sensor
[15:56] <edmoore> This channel is good for hardcore lurking
[15:56] <edmoore> I am a bit of a DIY drones lurker. have only posted a couple of times, but there's some super stuff going on there
[15:57] <edmoore> I thing the UAV dev board is an absolutely excellent project
[15:57] <Laurenceb> a month or so ago I was going to buy it
[15:57] <Laurenceb> as I had a nice plan or completely solving all the issues with the existing firmware
[15:57] <Laurenceb> tho I hate dspic
[15:57] <edmoore> I have basically cloned it for Hobble, but using Analog Sensors and trying to make the whole thing a munch more sensitive to low rates
[15:58] <edmoore> + AVR
[15:58] <Laurenceb> but I remain to be convinced by the pitot sensor, especially after looking at the code they use
[15:58] <Laurenceb> edmoore: you should have used the AD IMU
[15:58] <edmoore> expensive and not such good sensing for what i want
[15:58] <edmoore> am using the 614 gyros
[15:58] <edmoore> 50 deg/s
[15:58] <Laurenceb> - there dont appear to be diff pressure sensors that are stable enough for what I want, but maybe I'm wrong
[15:59] <Laurenceb> I see
[16:02] <edmoore> bt42: do you have an autopilot project?
[16:11] <Laurenceb> I saw an interesting french <1gram UAV that used a flapping piezo sensor for airspeed determination
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[16:12] <Laurenceb> at low speeds of a few meters per second pitot tubes with pressure sensors arent up to the job as far as I can see
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[16:17] <Laurenceb> cant find the link now :-/ they used bare die pic18f and gold bonding
[16:18] <Laurenceb> and two completely stripped down optical mouse sensors from ground avoidance
[16:19] <SpeedEvil> neat
[16:19] <Laurenceb> it assumed there was no wind then used the airspeed and mouse outputs to "scan" the ground height
[16:20] <Laurenceb> and get rate feedback for throttle/rudder control
[16:20] <SpeedEvil> yeah. If you want nice repeatable GNC output, you absolutely need complexity
[16:20] <SpeedEvil> If you want something that mostly works, you can get a lot, lot simpler
[16:23] Nick change: jasonb_ -> jasonb
[16:26] <Laurenceb> they had a little flap on the trailing edge to shed vortices, these flapped a little piezo sensor
[16:27] <Laurenceb> the frequency of flapping corresponded to the airspeed
[16:27] <Laurenceb> also the "cameras" looked to either side so it could avoid walls and fly around inside a building doing SLAM (ignorng air currents)
[16:32] <Laurenceb> think it was done by these guys http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V16-4VNH416-2&_user=585204&_rdoc=1&_fmt=&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1086695554&_rerunOrigin=google&_acct=C000029838&_version=1&_urlVersion=0&_userid=585204&md5=9e5b9a57d66a35b149cdbf5fc28df604
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[16:54] <rjharrison_> I want a uav
[16:54] <rjharrison_> That would be cool payload retrival
[16:57] <russss> balloon-launched UAV?
[16:58] <Laurenceb> mabe I'll launch the rogallo again soon
[16:58] <Laurenceb> too busy atm :-(
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[17:02] <rjharrison_> Paraglider UAV
[17:02] <rjharrison_> Icarus V
[17:02] <edmoore> I really cannot wait for someone to do that
[17:02] <rjharrison_> edmoore have UKHAS played with paragliders
[17:03] <russss> is it legal to launch a winged craft from a balloon in the UK?
[17:03] <edmoore> http://www.youtube.com/watch?v=HU2tymr4Rs0
[17:03] <rjharrison_> Laurenceb didn't you have something like that
[17:03] <edmoore> I was at the controls, although control is an ambitious term to use
[17:03] <rjharrison_> russss probably not
[17:03] <Laurenceb> I have a rogallo
[17:04] <Laurenceb> IMO its way better than parafoil as you can cruise faster
[17:04] <Laurenceb> - easier to get a good glide ratio with a decent airspeed
[17:05] <Laurenceb> depends, if you had a decent parafoil you might be able to get good performacne
[17:05] <Laurenceb> but using modified kites its not up there with a rogallo
[17:06] <russss> although aircraft lighter than 7kg are fully exempt from CAA licensing. I'm not sure to what altitude
[17:06] <russss> oh. 400ft.
[17:06] <Laurenceb> I'll fly as soon as I have enough free time to get it prepared and get to Cam, but I'm busy atm. The last flight demonstrated controlled glide down to the ground in some regions of heavy turbulence as well
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[17:06] <Laurenceb> unfortunately the steering line was damaged
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[17:07] <Laurenceb> and some glitchyness caused by sats dropping in/out caused a sanity check to fail so it wasnt steering all the time anyway
[17:08] <Laurenceb> but with a UM12 module and ublox5 (Flacon FSA-3) you could probably make it easier and have uplink capability
[17:08] <Laurenceb> I'm going to switch the GPS to ublox5 for the next flight
[17:08] <rjharrison_> Humm I'm going to have a go at this
[17:08] <Laurenceb> all my code is on the wiki
[17:09] <Laurenceb> need to upload some detailed design drawings with CofG ect, but I'm too lazy
[17:09] <rjharrison_> I think UAV paraglider return has got to be the way forward
[17:09] <rjharrison_> No more tree climbing for me :)
[17:09] <edmoore> it's a toughy
[17:09] <Laurenceb> I'm not convinced by parafoils unless we want to do lots of sewing
[17:09] <edmoore> I agree with Laurenceb - don't use ram-air parafoils
[17:10] <rjharrison_> edmoore what are your 30 second view on this
[17:10] <edmoore> glide ratios are the least of your worries with those
[17:10] <Laurenceb> IMO I've got the problem cracked with rogallo wings
[17:10] <Laurenceb> I got more than enough data from my last flight to do a ton of matlab sims/tests ect
[17:10] <rjharrison_> So a rogallo has better directin
[17:10] <rjharrison_> n
[17:10] <edmoore> semi-rigid wings couples to the main payload - you have to be abl to resist a torque between flight surface and payload
[17:11] <Laurenceb> - it was logging everything at 50Hz for the entire glide down from 10Km :P
[17:11] <edmoore> otherwise you fall foul of a phenomena called the Added Mass Effect
[17:11] <edmoore> essentially the dynamics of a flying vehicle depend upon both its own mass/inertia and the mass/inertia of the air it is accelerating
[17:11] Action: Laurenceb uses CofG shift to steer
[17:12] <rjharrison_> Yep that is more or less a give
[17:12] <rjharrison_> What the problem with air ram
[17:12] <edmoore> A parafoil at 30km has no air to accelerate and so the C0G shifts right down towards the thing hanging under it, making it very unstable
[17:12] <rjharrison_> So deploy at 2k
[17:12] <Laurenceb> then you cant go anywhere
[17:12] <rjharrison_> para back from 30k
[17:13] <edmoore> this means a small wobble in your system will not be corrected by the CoG very easily, and in simulation oftem leads to the parafoil collapsing infront of the vehicle and wrapping itself around it
[17:13] <rjharrison_> Humm I want to go to the nearest big open field
[17:13] <edmoore> which is A Bad Thing
[17:13] <rjharrison_> so 2k should give ample time
[17:13] <edmoore> rjharrison_: I agree with you actually that that is the better option - sit tight until 10km alt, say, then try and steer
[17:13] <rjharrison_> ok 5k
[17:14] <edmoore> but you'd need a pretty good set of safe landing sites
[17:14] <rjharrison_> Ulink the gps coods
[17:14] <Laurenceb> you can search through predefined areas
[17:14] <rjharrison_> based on google maps below
[17:14] <Laurenceb> and see whats achievable
[17:14] <Laurenceb> no need for uplink
[17:14] <rjharrison_> I guess you could pre load about 50 good sites and aim for the nearest
[17:15] <Laurenceb> not exactly
[17:15] <rjharrison_> Perhaps 500
[17:15] <Laurenceb> nearest after accounting for wind
[17:15] <rjharrison_> yep after 5 mins of free flight
[17:15] Action: rjharrison_ wonders how much time you have under a paraglider from 5km
[17:16] <Laurenceb> 15 minutes maybe
[17:16] <rjharrison_> ok so 2 mins of free flight
[17:16] <Laurenceb> I went with rogallo as I want to get back to the launch site
[17:17] <rjharrison_> some with the wind and some into the wind to get some idea of ground speed
[17:17] <rjharrison_> and then aim for a landing position
[17:17] <rjharrison_> I know it will vary with alt
[17:17] <rjharrison_> but might be worth a go
[17:17] <Randomskk> why not gps to get ground speed?
[17:18] <rjharrison_> yep
[17:18] <rjharrison_> Will go
[17:18] <rjharrison_> do
[17:18] <Laurenceb> I just recorded wind on the way up
[17:18] <rjharrison_> but you would want to see what happens if you want to circle around your position
[17:18] <rjharrison_> Yep true Laurenceb
[17:19] <Laurenceb> there are ways to find the wind for statistical techniques on your data
[17:19] <rjharrison_> Ok i'll put this on the burner for icarus V
[17:19] <Laurenceb> but when I simmed it it looked like they were too prone to noise
[17:19] <rjharrison_> Well I guess I'll have to do some testing
[17:20] <rjharrison_> Lots of teathered launches cool
[17:20] <rjharrison_> right I have to do some work
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[17:50] <RocketBoy> Hey Laurenceb - you might know the answer to this one - given your experience with different GPS modules.
[17:50] <RocketBoy> I'm thinking of using the GPS time as a packet radio time-slot reference – something simple to start with – like 1 second time slots on a 10 second cycle (i.e. 10 timeslots).
[17:50] <RocketBoy> I was wondering – rather than use the GPS 1PPS outputs – could I use the seconds unit digit appearing in NMEA strings.
[17:51] <RocketBoy> Obviously the serial interface bitrate comes into this – but allowing for that:How much would you expect time lock to vary between module types for a HAB flight.
[17:51] <Laurenceb> maybe +-100ms or more
[17:51] <RocketBoy> How much processor time does it take from the GPS “reference point” to reporting it via NMEA.
[17:51] <Laurenceb> lots of the modules use a RTOS
[17:51] <Laurenceb> and the data formatting is a low priority task
[17:52] <rjharrison_> YOu can get time sync from the GPS's
[17:52] <rjharrison_> IIRC
[17:52] <rjharrison_> I'm sure the lassen has a pin for this
[17:53] <RocketBoy> yeah - there is normally a 1 pulse per second or 10KHz reference pin (or both)
[17:53] <Laurenceb> RocketBoy: you dont need to sync like that
[17:53] <Laurenceb> you can use a DLL
[17:53] <rjharrison_> thats me leading the conv. astray :)
[17:54] <Laurenceb> and sync to the bit edges
[17:54] <RocketBoy> but for example if the time reported is 00:00:01 is the 1Hz pluse occuring at 00:00:00, 00:00:01 or 00:00:02
[17:54] <Laurenceb> I have some code its just not tired together into a nice application
[17:55] <Laurenceb> RocketBoy: the datasheet should help
[17:56] <RocketBoy> the idea is to come up with a standard to alow multiple simultanious flights on the same frequency
[17:56] <Laurenceb> http://www.copypastecode.com/14206/
[17:56] <Laurenceb> ah ok
[17:57] <Laurenceb> I put that together as a DLL
[17:57] <Laurenceb> http://pastebin.com/mbd8cb9f
[17:57] <Laurenceb> thats for aquiring an FM signal
[17:58] <RocketBoy> how does that help multiple simulatinius flights?
[17:59] <Laurenceb> it doesnt :P
[17:59] <Laurenceb> I though you wanted to bit sync
[17:59] <RocketBoy> nope - packet sync
[17:59] <RocketBoy> or timeslot sync really
[18:01] <RocketBoy> I guess with a 1sec pulse could be sub-divided into 10 x 100ms slots - but I think thats way too short to allow for transmitter to power up packet pre-amble & receiver AGC to kick in
[18:01] <rjharrison_> Humm there is a bit about getting time in the lasseniQ manual correct to 50ns
[18:02] <RocketBoy> sounds good enough - but we weould need the same for other GPS modules that we use
[18:03] <rjharrison_> Yep
[18:03] <Laurenceb> heh you have to consider the coax to the GPS ant
[18:03] <Laurenceb> with that sort of time resolution
[18:04] <RocketBoy> what speed of light stuff ?
[18:04] <rjharrison_> Off hime
[18:04] <rjharrison_> home
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[18:04] <Laurenceb> yes
[18:05] <RocketBoy> 1 second gives 300,000 Km - so the length of the coax is more of less irrelivant
[18:06] <RocketBoy> or
[18:07] <Laurenceb> compared to 50ns
[18:08] <RocketBoy> oh - I see yes relative to time reporting to that sort of resolution you would have to worry about co-ax lenth
[18:09] <Laurenceb> also ant bandwidth
[18:09] <RocketBoy> but to be worried about 50ns you would have to bw working at well over 10Mbps
[18:10] <RocketBoy> well 1Mbps anyway
[18:11] <RocketBoy> (or rather symbol rate)
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[19:01] <jcoxon> evening all
[19:06] <RocketBoy> yo jcoxon
[19:07] <RocketBoy> jcoxon: how far off a new ballast... flight do you think you are?
[19:08] <jcoxon> RocketBoy, well made a sort of break through yesterday concerning ballast volume sensing
[19:08] <jcoxon> so potentially have that sorted
[19:08] <jcoxon> am now going back to look at my valve set up
[19:08] <jcoxon> i think its just too slow
[19:09] <jcoxon> the tube size is too small
[19:09] <jcoxon> wouldn't mind your thoughts on that
[19:09] <jcoxon> i reckon i could be ready and tested in about 2 weeks
[19:10] <RocketBoy> really - I wouldn't have thought speed of dump was that important
[19:10] <jcoxon> its not
[19:10] <jcoxon> but its incredibly slow ;-p
[19:10] <RocketBoy> what size bore is the tube?
[19:10] <jcoxon> 1.6mm
[19:11] <jcoxon> need to have a play around
[19:11] <RocketBoy> I guess its sort of slow drip speed then?
[19:11] <jcoxon> yeah
[19:11] <jcoxon> was looking at peristaltic pumps (coming from my medical background)
[19:11] <RocketBoy> whats the bore of the valve?
[19:12] <jcoxon> so the orifice is 1.143mm
[19:12] <RocketBoy> peristatic pumps must be a synch to make
[19:12] <jcoxon> or purchase - they are fairly cheap
[19:12] <RocketBoy> personally i like the idea of pumps (but you know that0
[19:12] <RocketBoy> )
[19:13] <jcoxon> why do you like the idea?
[19:14] <RocketBoy> i guess it seems more positive rather than hoping for gravity feed flow
[19:14] <RocketBoy> in sort of unknown environment
[19:14] <jcoxon> yeah
[19:14] <jcoxon> i think perhaps a 6v peristaltic pump
[19:15] <RocketBoy> peristaic pumps are great cos they give you a known quanity per rev
[19:15] <jcoxon> thats very true
[19:15] <jcoxon> so that coupled with out new ballast sensor and we are sorted
[19:16] <RocketBoy> I guess you gon't even need the sensor - assuming pump is working correctly
[19:16] <RocketBoy> and you can measure the revs
[19:16] <Laurenceb> hi jcoxon
[19:16] <Laurenceb> jcoxon you are a genious
[19:16] <jcoxon> Laurenceb, haha, thanks i guess :-)
[19:16] <jcoxon> RocketBoy, the sensor is nice and simple
[19:17] <jcoxon> RocketBoy, okay the final issue...
[19:17] <Laurenceb> jcoxon: you want to get a photodiode from farnell
[19:17] <jcoxon> a secure method of putting our tubing into the tank itself
[19:18] <Laurenceb> I was thinking threaded bar through the bottle top
[19:18] <Laurenceb> and drill a hole through the middle of the bar
[19:18] <Laurenceb> really wants to be done on a lathe
[19:18] <Laurenceb> jcoxon: you could mount the led externally in a vertical tube alongside the tank
[19:18] <jcoxon> how about something like http://www.williamson-shop.co.uk/plug---6mm-hosetail-valved-25sbtf06mpx-984-p.asp
[19:19] <Laurenceb> jcoxon: that way you dont have to touch the tank
[19:20] <Laurenceb> youd need an op amp circuit to interface the photodiode to the adc
[19:21] <SpeedEvil> I'm unsure that a resistor won't work
[19:21] <SpeedEvil> maybe a cap too
[19:22] <SpeedEvil> 1M or so resistor pulling high, 1nF cap or so across the ADC pin and ground, diode between ADC pin and ground
[19:22] <jcoxon> Laurenceb, the led is mounted in a tube that has liquid in it (at the same level as the tank)?
[19:22] <Laurenceb> yeah unfortunately the ADC on the flight computer has lower input impedance
[19:22] <SpeedEvil> Laurenceb: a simple single transistor amp ...
[19:22] <Laurenceb> http://image.ec21.com/image/ciya/pre_GC02816045/Water_Tube_Steam_Boiler.jpg
[19:23] <Laurenceb> jcoxon - see the tube up the side
[19:23] <Laurenceb> imagine thats the sensor
[19:23] <Laurenceb> only the top is open to the air, and the bottom is plumbed into the drain hose
[19:24] <jcoxon> i see so as there is a connection the level is the same in both
[19:24] <Laurenceb> yep
[19:25] <jcoxon> Laurenceb, that still requires a custom tank
[19:25] <Laurenceb> nope, just a 3L bottle
[19:25] <Laurenceb> with a tapped top and a vent hole
[19:29] <RocketBoy> (mount the led and diode in a long black walled open ended tube
[19:29] <jcoxon> RocketBoy, does that then just sit in the centre of the tank
[19:30] <RocketBoy> yeah wherever you like - just needs to fill with liquid
[19:31] <RocketBoy> its saves having to have a black walled tank
[19:31] <jcoxon> true
[19:31] <jcoxon> hmmm will a pump freeze up
[19:31] <Laurenceb> turn the led on off and take adc readings
[19:31] <Laurenceb> then average
[19:31] <Laurenceb> jcoxon: likely
[19:31] <Laurenceb> that solenoid valve is specced for low temperature
[19:32] <RocketBoy> you have to allow for sensor non-linearity - and average with changing ambient light will be an issue
[19:33] <Laurenceb> yes you want to filter it all out
[19:33] <RocketBoy> which is why it needs shielding from light IMO
[19:34] <Laurenceb> but in an idea world there will be light leaks
[19:34] <Laurenceb> so you still want to average
[19:34] <jcoxon> right now with my set up
[19:34] <RocketBoy> and which light frequency isn't present in sunlight?
[19:34] <Laurenceb> most
[19:34] <jcoxon> no LED reads 5 and with led 300 - 400
[19:34] <jcoxon> right will bbl
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[20:00] <Laurenceb> http://www.nebula-aerospace.com/news/archive/fuelflow.asp
[20:00] <Laurenceb> he really has lost it
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[20:01] <Laurenceb> During ascent, high pressure compressed air is fed from the onboard aerodynamic compressors and storage system after first being cooled to reduce its temperature and increase its density.
[20:02] <SpeedEvil> Yes.
[20:02] <SpeedEvil> The prize is not how much complex hardware can you smash into the ground.
[20:02] <SpeedEvil> Also.
[20:05] <Laurenceb> but the valve make sense - the solenoid valves are obviously for isolation and the ball valves for throttling
[20:05] <Laurenceb> should work
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[20:05] <SpeedEvil> o - I thought that was n-prize
[20:05] <SpeedEvil> for which that's barking mad
[20:26] <Jon_Apex> evening
[20:29] <Laurenceb> http://www.youtube.com/watch?v=_x5IziyOcAg
[20:29] <Laurenceb> wtf
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[21:34] <Laurenceb> http://en.wikipedia.org/wiki/ATREX
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[22:05] <Laurenceb> gtg, cya
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[23:40] <jcoxon> sweet - google wave invitation has arrived :-p
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[23:41] <Randomskk> yup mine just did too
[23:41] <Randomskk> how exciting
[23:43] <edmoore> mine hasn't
[23:43] <edmoore> oh, it has
[23:43] <edmoore> woops
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[00:00] --- Wed Nov 11 2009