highaltitude.log.20080815

[00:00] Action: fergusnoble has removed most of the skin from both his fingers from sanding the mould
[00:00] <fergusnoble> s/fingers/thmbs
[00:00] <Laurenceb> :(
[00:01] <Laurenceb> already done that here from sanding door frames for the past week
[00:03] <fergusnoble> it turns out the best way to sooth it is holding a cold pint
[00:04] <fergusnoble> :)
[00:04] <Laurenceb> hehe
[00:11] <Laurenceb> hmm looks like I must have a duff transistor :(
[00:11] <Laurenceb> oh well early start tomorrow, cya all
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[07:59] <Shanuson> good morning
[08:00] <jcoxon> good morning
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[08:02] <icez> hah. old news but astronomers made the first map of an exoplanet, and they found it "may" have jetstream-like winds of 6000 mph
[08:12] <gordonjcp> hm
[08:12] <gordonjcp> well, as long as it stays dry...
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[08:33] <akawaka> gnight
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[09:03] <gordonjcp> edmoore: morning
[09:03] <edmoore> morning gordonjcp. all well?
[09:05] <gordonjcp> yeah, not bad
[09:05] <gordonjcp> I have some yagis, with nicely bent driven elements
[09:05] <gordonjcp> and the burns are healing up well too
[09:05] <gordonjcp> I should go and buy some welding gloves
[09:08] <gordonjcp> edmoore: and you?
[09:09] <edmoore> my server is being annoying, but at work now so can't fiddle
[09:09] <edmoore> otherwise good
[09:09] <edmoore> stitching some (hopefully) very stable parachutes for the new payload
[09:10] <gordonjcp> cool
[09:10] <gordonjcp> I'm going to try listening for the balloon at the house
[09:10] <edmoore> I've been reading lots of stuff on parachute stability at work
[09:10] <gordonjcp> but I suspect I'm going to need to get up a hill somewhere
[09:18] <jcoxon> gordonjcp, :-D
[09:18] <jcoxon> i've ordered another radiomodule to make into a beacon
[09:18] <gordonjcp> cool
[09:19] <jcoxon> so that you should be able to hear something :-)
[09:19] <gordonjcp> well with the yagi I get fairly weak signals off the cubesats even once they're theoretically a bit over the horizon
[09:20] <jcoxon> will be very interesting to see what you can pick up
[09:20] <gordonjcp> yeah
[09:20] <jcoxon> would be amazing to have a long range station
[09:20] <gordonjcp> I ought to be able to hear *something*
[09:20] <jcoxon> yeah
[09:20] <gordonjcp> although iirc it's 10mW?
[09:20] <jcoxon> yeah
[09:21] <gordonjcp> maybe I should build a 6-ele
[09:21] <jcoxon> hehe
[09:21] Action: jcoxon can see gordonjcp taking over jodrell bank
[09:21] <gordonjcp> I remember being able to hear weather balloon radiosondes on AM CB frequencies years and years ago
[09:21] <edmoore> gordonjcp: 13 is what it's all about
[09:22] <jcoxon> right i'll bbiab got to go and collect the post
[09:22] <gordonjcp> ok
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[12:47] <edmoore> hi jcoxon , walters
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[14:13] <jcoxon_> hey edmoore
[14:14] <edmoore> ello
[14:14] <jcoxon_> hows tricks?
[14:27] <edmoore> not bad, designing a parachute
[14:27] <edmoore> obv
[14:27] <edmoore> and actually looking forward to 5pm as I'm a bit jiggered
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[16:22] <gordonjcp> http://www.aleutia.com/products/
[16:31] <edmoore> that would be absolutely perfect for the chase car computer
[16:31] <gordonjcp> yeah
[16:32] <gordonjcp> 250 quid for the one with the 80G laptop drive
[16:32] <gordonjcp> 200 if you're happy to have no wifi and a CF card
[16:32] <edmoore> it can be the wireless access point, do the wireless broadband and gps duties, and so on
[16:32] <edmoore> CF card doesn't bother me too much
[16:34] <gordonjcp> I've never been that bothered by running mechanical hard drives in a moving vehicle
[16:35] <gordonjcp> everyone goes on about how the shock and vibration kill them, but generally I've found them to be OK
[16:36] <edmoore> I'd just be after the guts of that thing
[16:36] <edmoore> run openbsd off it
[16:36] <gordonjcp> "lol openbsd"
[16:37] <gordonjcp> Theo de Raant doesn't seem to like me
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[16:42] <edmoore> who he?
[16:43] <gordonjcp> the guy behind OpenBSD
[16:43] <gordonjcp> to be fair, I do really have a lot of respect for the guy
[16:43] <gordonjcp> in particular his insistence on open firmware for devices supported in OpenBSD
[16:44] <gordonjcp> but in the podcast I used to co-present I took the piss out of OBSD a lot
[16:44] <gordonjcp> and in particular TdR's habit of changing what he defined as a vulnerability
[16:44] <gordonjcp> and the use of the term "errata" to describe a remote root hole
[16:45] <gordonjcp> I know he's terribly attached to the "X years without a remote vuln" thing, but really
[16:47] <edmoore> I've never actually used openbsd. maybe I'm a vistim to the hype
[16:53] <gordonjcp> well
[16:53] <gordonjcp> at the time of the "errata" thing, I said that it was a bit like when you're a kid
[16:53] <gordonjcp> and you're playing tig or something
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[16:54] <gordonjcp> and there's *always* one kid who makes up rules to explain why you didn't just tig him, for increasingly tenuous reasons
[16:54] <gordonjcp> and then I started getting snotty emails from OpenBSD fanbois
[16:55] <edmoore> :)
[16:55] <edmoore> well, I'll stick with my ubuntu. I don't know any better
[16:55] <gordonjcp> I like ubuntu but I don't like the IRC channel ;-)
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[16:56] <robert1971> hi all
[17:00] <edmoore> hi robert1971
[17:00] <edmoore> gordonjcp: yes the channel is hard work
[17:00] <edmoore> ubuntu-server has slightly more helpful answers usually
[17:00] <edmoore> a bit more signal to noise, anyway
[17:01] <robert1971> is the ukhas.org.uk site down or is there some bad routing shit going down in the uk today
[17:02] <robert1971> In Holland at the moment
[17:02] <robert1971> working now weird
[17:04] <gordonjcp> robert1971: wfm, wiki.ukhas.org.uk is a tad slow
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[20:50] <fergusnoble> does anyone here know much about stepper motors?
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[20:53] <edmoore> fergusnoble: try me
[20:53] <fergusnoble> i thought you were out partying :)
[20:54] <edmoore> may yet still be
[20:54] <edmoore> but first I want to log into my server
[20:54] <edmoore> and faff
[20:54] <fergusnoble> ok, so would a standard size 23 motor be able to turn a large roll of film?
[20:54] <fergusnoble> it will be on bearings
[20:54] <fergusnoble> but the roll might weight like 20kg
[20:55] <edmoore> not without a decent reduction
[20:55] <edmoore> but nema 23 or 35 are ebay stallwarts so I guess design around using them as they're available
[20:55] <fergusnoble> yeah
[20:55] <fergusnoble> the 35 seem a big jump in price
[20:56] <fergusnoble> i guess i should work out the moment of inertia of the roll
[20:56] <fergusnoble> but i dont think the rolling resistance of the bearing will be that negligable
[20:57] <fergusnoble> your the engineer, how do i work out what gearing or what torque i need? :)
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[20:59] <edmoore> it's nowt to do with moment of inertia, that just affects acceleration. You want the working friction level to be the primary design driver, so you can work out the torque required to do the job
[20:59] <edmoore> if you're doing it properly, you then find the performance curves for your motor and then try and size the motor according to making the max efficieny at the working torque
[20:59] <fergusnoble> how do i work out the working torque?
[20:59] <edmoore> but nema 35 stepper have, what, 250 oz-in?
[21:00] <edmoore> you'll have to measure it for the black device in question
[21:00] <edmoore> and just get a data point for a speed and a torque at that speed
[21:00] <edmoore> and find a stepper capable of doing it
[21:01] <edmoore> they have totally different torue responses so ignore everything I just said
[21:02] <fergusnoble> some size 23 ones i was looking at are rated for 1Nm holding
[21:02] <edmoore> that sounds fair, though obviously less at a given speed
[21:02] <fergusnoble> ok so i have to build the rest of it first :)
[21:03] <edmoore> basically
[21:03] <edmoore> but tbh if you can make rough guesses, you'll probs be ok
[21:03] <fergusnoble> ok
[21:03] <edmoore> and if it's not good enough, bolt a fan onto it and up the voltage
[21:04] <fergusnoble> i can put a large reduction on it as the rolls dont have to turn very fast
[21:04] <fergusnoble> and do you think its a good idea to use a stepper on the roll the material is coming from driven at a lower speed to provide tensioning in the film
[21:11] <edmoore> hrm
[21:11] <edmoore> maybe...
[21:11] <edmoore> not a stepper motor, maybe a dc gear motor
[21:12] <edmoore> and just keep it at stall but with a low current via pwm
[21:12] <edmoore> steppers have very coggy behaviour when you force them against stall
[21:12] <edmoore> brushless dc would provide a continuous torque
[21:13] <fergusnoble> maybe i should just use dcs thoughout
[21:13] <fergusnoble> as i want to be able to run the system backwards too
[21:13] <edmoore> fair enough
[21:14] <edmoore> well maybe use steppers throughout provided the control is ok
[21:14] <edmoore> you just dont want to have them slightly out of sync otherwise you'll end up stretching a gore apart
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[21:21] <fergusnoble> could i do something like get the tensioning stepper to hold its position but only drive it with less current
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[21:26] <fuzzylugnuts> poof!
[21:28] <fuzzylugnuts> I just got 2 microtrak-300s in ^_^
[21:29] <SpeedEvil> fergusnoble: with conventional steppers, at zero current they have one holding torque.
[21:29] <SpeedEvil> fergusnoble: this is quite small.
[21:29] <SpeedEvil> fergusnoble: as you raise the current to the nominal current, the torque rises from zero to the nominal torque.
[21:29] <SpeedEvil> However.
[21:30] <SpeedEvil> Once you exceed this torque, it'll probably slip, and carry on slipping, there is nothing active to stop it - there will be some braking effect.
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[21:31] <fergusnoble> SpeedEvil: basically i have two rollers with plastic film being rolled between them
[21:31] <fergusnoble> say i put steppers on both
[21:31] <fergusnoble> can i use one stepper to drive and the other to put some tension into the plastic film?
[21:32] <SpeedEvil> That's really hard.
[21:32] <SpeedEvil> Without active position sensing.
[21:32] <SpeedEvil> this is for what?
[21:32] <fergusnoble> ok, because when the motor slips its no longer in the correct position of the step sequence?
[21:32] <SpeedEvil> you're trying to do a camera-keep-clear thingy?
[21:33] <fergusnoble> for making some chuffing huge zero pressure balloons :)
[21:33] <SpeedEvil> Ah.
[21:33] <SpeedEvil> What - you're thinking of making long tubes or stuff?
[21:34] <SpeedEvil> The trivial way is to have a light roller on a spring.
[21:34] <SpeedEvil> The film pushes it out of the way.
[21:34] <fergusnoble> yeah you start with a tube and then do some fancy stuff at the ends to cap it off
[21:34] <fuzzylugnuts> zero pressure they show up on ebay once in a while
[21:34] <SpeedEvil> you keep it in one position by playing with the tension.
[21:34] Action: SpeedEvil passes fergusnoble a bag sealer.
[21:34] <fergusnoble> fuzzylugnuts: we want the capability to make our own
[21:34] <fuzzylugnuts> *zero pressure balloons
[21:34] <fuzzylugnuts> ah ok
[21:35] <edmoore> never senn a zp on ebay
[21:35] <fergusnoble> fuzzylugnuts: also ours are going to need to be big, commercially they are very expensive
[21:35] <SpeedEvil> fergusnoble: how much lift?
[21:35] <fuzzylugnuts> this one was 50lbs
[21:35] <fergusnoble> SpeedEvil: like 10kg minimum
[21:36] <SpeedEvil> Zero pressure is a non-flexible balloon that's not inflated progressively, but just looks wrinkled on the ground?
[21:36] <edmoore> to 32 km, that is
[21:36] <fergusnoble> SpeedEvil: yeah on the ground the helium only inflates a small portion of the balloon
[21:37] <SpeedEvil> I wonder how long a tube balloon is practical.
[21:37] <fergusnoble> as the outside pressure drops they fill out
[21:37] <edmoore> it's easier to make
[21:37] <fuzzylugnuts> fergusnoble: do you have massive funding for the helium to fill this massive balloon?
[21:37] <SpeedEvil> Hydrogen!
[21:37] <SpeedEvil> Or methane.
[21:37] <fergusnoble> fuzzylugnuts: BOC are sponsoring us
[21:37] Action: SpeedEvil passes fergusnoble 18 tons of beans.
[21:38] <fergusnoble> its all free :)
[21:38] <fuzzylugnuts> win!
[21:38] <fuzzylugnuts> thats sweet
[21:38] <SpeedEvil> This is for the n-prize?
[21:38] <fergusnoble> hence the selling out on the nova6 photos
[21:38] <edmoore> fuzzylugnuts: http://www.srcf.ucam.org/~cuspaceflight/images/nova6selected/PICT1043.JPG
[21:38] <edmoore> one doesn't do that kind of thing for free :)
[21:38] <fuzzylugnuts> HAHA
[21:38] <fergusnoble> nope, not for n-prize per se
[21:39] <fergusnoble> but maybe a stepping stone
[21:39] <fergusnoble> its working towards a sub orbital 100km rocket
[21:39] <fergusnoble> *rockoon
[21:40] <fuzzylugnuts> edmoore: do all the cameras have to have BOC in their frame?
[21:40] <SpeedEvil> I don't see the need to go all teh way to 32Km for a rockoon.
[21:40] <edmoore> fuzzylugnuts: no
[21:40] <fuzzylugnuts> oh, good
[21:40] <edmoore> SpeedEvil: the real altitude will be decided on as a compromise between various competing factors
[21:41] <SpeedEvil> edmoore: yeah. With my simple simulator I was coming out with staging at around 30Km IIRC, after a few seconds coasting.
[21:42] <SpeedEvil> edmoore: it's all compromises.
[21:42] <fergusnoble> SpeedEvil: we hope to stage a lot higher than that
[21:42] <SpeedEvil> fergusnoble: this was with a rocket that was ground launched, and went up at M0.8 or so till 10Kmish
[21:43] <SpeedEvil> fergusnoble: the first stage essentially accelerated to high subsonic and sat there till Q went down to sensible figures before accelerating.
[21:43] <fergusnoble> ah ok, ground launch is a very different problem i think
[21:43] <SpeedEvil> So it wasted a _lot_ in atmosphere.
[21:44] <fergusnoble> so, any ideas on film tensioning?
[21:45] <fergusnoble> SpeedEvil: do you think it might be simpler with DC motors?
[21:45] <SpeedEvil> fergusnoble: Is this for assembly on the ground?
[21:45] <SpeedEvil> It may well be, yes.
[21:45] <fergusnoble> SpeedEvil: where else would we assemble it?
[21:45] <fergusnoble> :)
[21:46] <SpeedEvil> fergusnoble: I was thinking of a simple roll on the ground, with a filled bubble.
[21:46] <SpeedEvil> It rolls out as you deploy it.
[21:46] <SpeedEvil> However.
[21:46] <fergusnoble> this is for when we are making it in the first place
[21:47] <SpeedEvil> DC motors are probably the right soltuion - they have nicely proportional torque and current over a moderate range.
[21:47] <SpeedEvil> Altertnatively, you can watch the sag of the film.
[21:47] <fergusnoble> ok, is the control easy? can i just pwm them or do i need proper constant current supply or something?
[21:47] <SpeedEvil> PWM - over a certain frequency will work just fine.
[21:48] <fergusnoble> ok, sweet
[21:48] <fergusnoble> DC it is then
[21:48] <fergusnoble> seeing as i dont need position control i guess steppers are overkill
[21:48] <SpeedEvil> How are you making it?
[21:48] <fergusnoble> i only need constant speed
[21:48] <SpeedEvil> Couple of really long rollers, and seal lots of bits of film before winding up or something?
[21:49] <fergusnoble> so we have two rollers and between them is a continuous band sealer
[21:49] <SpeedEvil> So you make a pipe?
[21:49] <fergusnoble> we use film that is folded in half on the rolls so we only need to weld at one side
[21:49] <fergusnoble> we make a pipe out of many segments yeah
[21:50] <fergusnoble> and then finish the top and bottom by hand
[21:50] <fergusnoble> we have made some 7m ones totally by hand
[21:51] <SpeedEvil> Oh - so there are many vertical 'stripes' of film welded into one large balloon?
[21:51] <fergusnoble> yeah
[21:51] <SpeedEvil> How thin film?
[21:51] <fergusnoble> they are called gores in ballon terminology
[21:52] <fergusnoble> ~25 microns
[21:52] <fergusnoble> we made on in 9micron film and it was a pita
[21:52] <SpeedEvil> Workable, but not too insane.
[21:52] <SpeedEvil> what length?
[21:52] <SpeedEvil> and diameter?
[21:52] <fergusnoble> it had a complex shape, was shaped like a hot air ballon
[21:52] <fergusnoble> so no streight welds
[21:53] <SpeedEvil> Eww.
[21:53] <fergusnoble> took ages, was maybe 5m diameter
[21:53] <fergusnoble> so then we decided to go for thicker film and simpler geometry
[21:53] <SpeedEvil> I can imagine lots of easy ways to do it.
[21:54] <edmoore> SpeedEvil: youtube for 'fructose pomposity'
[21:54] <SpeedEvil> Annoyingly, they start out 'first obtain a _really_ large building'.
[21:54] <edmoore> or is it diminuative turtlenecks? I can never remember
[21:55] <SpeedEvil> The millenium dome!
[21:55] <SpeedEvil> All we need is some helium, and it could just work.
[21:55] <fergusnoble> SpeedEvil: hopefully using the rollers we can do it without much space
[21:55] <fergusnoble> as 90% of the material is rolled up at any one time
[21:56] <fergusnoble> we are looking to be making them 40m long ish
[21:56] <fergusnoble> so its a lot of material to work with, the logistics of handling it all layed out is hard
[21:57] <SpeedEvil> I wonder if a simple solution might be 9um thick stuff, and a completely automated fill/launch.
[21:57] <fergusnoble> http://www.youtube.com/watch?v=uK80MXHQ5hA
[21:57] <SpeedEvil> You fill a bubble on the end, and simply launch a _really_ long balloon by reeling it off, sealing as you go.
[21:57] <fergusnoble> im the hairy one poking it :)
[21:57] <fuzzylugnuts> very pretty balloon!
[21:58] <fuzzylugnuts> good job
[21:58] <SpeedEvil> That's 25um?
[21:58] <fergusnoble> the trouble with the 9um stuff is it doesnt weld without burning through
[21:58] <fergusnoble> thats the 9um ones
[21:59] <fergusnoble> so you have to put two layers of thicker film in at the seams
[21:59] <fergusnoble> one top and bottomw
[21:59] <fergusnoble> you also need it to take the load off the bulk film
[21:59] <SpeedEvil> :/
[21:59] <fergusnoble> with the thicker film you can just weld two sheets together straight
[22:00] <SpeedEvil> I suppose you could make a welder that rolled a couple of cm spool of thicker onto the 9um.
[22:00] <fergusnoble> SpeedEvil: thats exactly how we did it
[22:01] <fuzzylugnuts> edmoore: I just emailed my old group's lead telling him to get Norco to donate helium
[22:01] <SpeedEvil> Sigh.
[22:01] <fergusnoble> we made some manual jaw style welders with spools fitted to reel out and position the thicker film over the weld
[22:01] <edmoore> it was special calibrated-width load tape
[22:01] <SpeedEvil> Somewhere I remember a link to rolls of film.
[22:03] <SpeedEvil> Ah yes.
[22:03] <SpeedEvil> http://www.nehydro.net/index.php?main_page=product_info&cPath=8&products_id=15&zenid=0609ef696b55de9df7d2863ba6f54875
[22:03] <SpeedEvil> 'gardening'
[22:04] <fergusnoble> mylar doesnt heat weld unfortunately
[22:05] <fergusnoble> we have a supplier in the uk of some special zero pressure balloon film
[22:05] <SpeedEvil> :_)
[22:05] <fergusnoble> the guy who was making the balloons for the kinetic manned edge of space balloon thingy
[22:05] <SpeedEvil> Oh - that guy.
[22:05] <fergusnoble> andy elson
[22:06] <SpeedEvil> That's one way to solve the problem of microcontroller + tracking for cameras.
[22:06] <edmoore> 'e 'opped, 'e skipped, an' 'e jumped
[22:06] <edmoore> yeah, andy elson
[22:07] <fergusnoble> so if anyone else wants some i can pick it up when i put an order in from him
[22:07] <fergusnoble> i dont know the price yet
[22:07] <edmoore> one million doolllars
[22:08] <edmoore> oh unix is making me come apart
[22:08] <edmoore> I must go otu
[22:08] <edmoore> out
[22:08] <fuzzylugnuts> drink till your kernel panics
[22:08] <edmoore> I see what you did there
[22:09] <fergusnoble> edmoore: this is you http://www.xkcd.com/456/
[22:10] <edmoore> chris told me that too
[22:10] <edmoore> today's amused me
[22:10] <icez> lol
[22:10] <edmoore> i think I might have to use that line at some point
[22:12] <edmoore> "Imagine you're at a parent teacher conference, and the teacher reassures you that he always wears a condom whilst teaching"
[22:13] <fergusnoble> where do you think i could get a good motor?
[22:14] <edmoore> dc?
[22:14] <fergusnoble> something like an electric drill i think they use in robotics
[22:14] <edmoore> well I dunno, bull sometimes have something
[22:14] <fergusnoble> yeah dc
[22:14] <fergusnoble> bull?
[22:14] <edmoore> bull electrical
[22:14] <edmoore> hrm
[22:14] <edmoore> i have some windscreen wiper motors which would have more than enough torque
[22:15] <edmoore> but are worm drive which won't help you do the reverse torque
[22:15] <fergusnoble> do they go up to any kind of speed?
[22:16] <edmoore> windscreen wiper motor speed
[22:16] <edmoore> drill motors I guess
[22:16] <edmoore> see if technobots.co.uk have anything
[22:16] <edmoore> they'll probs be too fast on their own
[22:16] <fergusnoble> ok thanks for the info
[22:17] <edmoore> you could directly drive the surface of the roller with something
[22:17] <fergusnoble> was going to use a timing belt
[22:17] <edmoore> that way you'd have a constant tangetial speed, therefore weld feed speed, no matter what the radius of the roll
[22:18] <fergusnoble> i see, that could be good
[22:18] <fergusnoble> but harder to arange
[22:18] <fergusnoble> the motor would have to be able to move
[22:18] <fergusnoble> and might tug the film wierdly
[22:18] <edmoore> indeed, it'd need a spring pressing inwards radially
[22:18] <edmoore> you'd need a roller the width of the roll, I think
[22:19] <edmoore> sorry, the 'drive roller' would be the width of the roll
[22:19] <fergusnoble> could feed the film through a little wheel attached to an optical encoder
[22:19] <edmoore> indeed
[22:20] <fergusnoble> to provide speed feedback
[22:21] <fergusnoble> any idea roughly how many watts?
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[22:21] <Laurenceb> hi everyone
[22:21] <edmoore> oh god knows
[22:21] <edmoore> 50
[22:22] <edmoore> right, time to leave
[22:22] <edmoore> bbl
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[22:32] <Laurenceb> I cant open a com port on my machine in hyperterminal, any ideas?
[22:32] <fuzzylugnuts> is it in use?
[22:32] <Laurenceb> how can I check?
[22:32] <fuzzylugnuts> not too sure
[22:32] <Laurenceb> I'll ctrl-alt-del to see whats running
[22:33] <fuzzylugnuts> there is a better terminal program out there that may give you more information, I forget what its called. I can look it up though
[22:34] <Laurenceb> hmm its not having it
[22:34] <Laurenceb> and ctrl alt del doesnt reveal anything
[22:35] <Laurenceb> I'm using the usb-serial adaptor of a thinkpad on my acer and the driver is a bit dodgy
[22:35] <fuzzylugnuts> : /
[22:35] <fuzzylugnuts> try Realterm
[22:35] <Laurenceb> ah diconnecting the usb cable and plugging back in fixed it
[22:36] <fuzzylugnuts> win
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[22:39] <fuzzylugnuts> Byonics came out with a new product :D
[22:39] <fuzzylugnuts> http://www.byonics.com/microtrak/mtaio.php
[22:40] Nick change: jos -> Jos
[22:41] <Laurenceb> hmm seems any dodgy serial will screw up the usb adaptor so it has to be power cycled
[22:41] <fuzzylugnuts> weak
[22:41] <Laurenceb> there was a bit of silly serial code on my uC
[22:41] <Laurenceb> and it screwed the adaptor
[22:42] <Laurenceb> I would expect better from IBM
[22:42] <fuzzylugnuts> Yeah
[22:42] <Laurenceb> guess it could be the hacked driver I'm using
[22:42] <Laurenceb> but hard to see how, it looks like a lower level bug
[22:44] <fuzzylugnuts> mmm, bugs.
[22:44] <Laurenceb> I'm investingating transistor level convertors atm
[22:45] <Laurenceb> seeing how fast they can go
[22:46] <SpeedEvil> GHz done right.
[22:46] <SpeedEvil> you mean for RS232?
[22:47] <fuzzylugnuts> max232 chips are great for that.
[22:48] <Laurenceb> yeah, I'm just using some bc108
[22:48] <Laurenceb> but my convertor was failing above 9600 baud, so I'm investigating
[22:49] <SpeedEvil> what design?
[22:50] <Laurenceb> just potential divider
[22:51] <Laurenceb> bbl
[22:53] <fuzzylugnuts> arrrrrrrrrrrrrrrrg
[22:54] <fuzzylugnuts> torn between rechargeable batteries and non-rechargeable ones for flight
[22:54] <fuzzylugnuts> the non rechargeable ones are sooooo light
[22:54] <SpeedEvil> What non-rechargable?
[22:54] <fuzzylugnuts> energizer's photo lithiums
[22:55] <SpeedEvil> Li-po
[22:55] <SpeedEvil> It's the way to go.
[22:55] <fuzzylugnuts> helllll no
[22:55] <fuzzylugnuts> man I don't like those things
[22:55] <fergusnoble> fuzzylugnuts: yeah the non rechargable lithiums are so nice
[22:55] <fuzzylugnuts> they are such awesome shapes too
[22:55] <fergusnoble> but soooo expensive
[22:55] <SpeedEvil> li-po batteries are fun.
[22:55] <SpeedEvil> http://www.youtube.com/watch?v=4OsBc8RqSKU
[22:56] <fuzzylugnuts> I had one blow up already
[22:56] <SpeedEvil> Hmm.
[22:56] Action: SpeedEvil ponders li-po at low-pressure.
[22:56] <fuzzylugnuts> thats another thing
[22:56] <fuzzylugnuts> I wonder if some stuff would vaporises in near vacuum
[22:56] <fergusnoble> people have flown li-pos
[22:56] <SpeedEvil> AA shaped lithium cells are available.
[22:56] <SpeedEvil> And quite cheap.
[22:56] <fuzzylugnuts> yeah
[22:56] <fergusnoble> they dont go bang
[22:56] <SpeedEvil> As are 18650s
[22:57] <fergusnoble> but i think jcoxon might have had an issue with then on one flight, im not sure
[22:57] <SpeedEvil> http://www.dealextreme.com/details.dx/sku.1213
[22:58] <SpeedEvil> this sort of cell is ~18g for 7.5Wh ish
[22:58] <fuzzylugnuts> I use A123's lithium iron phosphate ones
[22:58] <fuzzylugnuts> but they are just too heavy
[22:58] <fuzzylugnuts> their C rating is soooo high
[23:00] <SpeedEvil> IMO - the above sort of cylindrical li-ion is unconditionally safe in this environment.
[23:00] <SpeedEvil> The only problem that can happen is if you overheat them, but that won't be happening.
[23:00] <fuzzylugnuts> yeah
[23:00] <fuzzylugnuts> the metal can is plenty of protection
[23:01] <fuzzylugnuts> http://data.energizer.com/PDFs/crv3.pdf
[23:01] <fuzzylugnuts> I was going to use 2 of those
[23:02] <SpeedEvil> That's about twice the weight, and not much more capacity than the above li-ion.
[23:02] <fuzzylugnuts> yeah, I saw
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[23:03] <fuzzylugnuts> the A123 1Ah versions weight ~40-50g if I remmeber
[23:03] <fuzzylugnuts> total overkill
[23:03] <SpeedEvil> A123 sucks.
[23:03] <fuzzylugnuts> heh
[23:03] <SpeedEvil> If you don't care about power/weight
[23:04] <SpeedEvil> In my UAV, I really, really do.
[23:04] <SpeedEvil> (paper UAV as yet)
[23:04] <SpeedEvil> It discharges the A123 cells in 3-4 mins.
[23:04] <SpeedEvil> 400W in a 1KG device is fun!
[23:05] <SpeedEvil> Especially when the fly-by-wire gets confused, and it smashes into the ground at 100MPH.
[23:05] <fuzzylugnuts> A123's won't catch fire if you mangle them to pieces, thats one of the things they sell on
[23:06] <SpeedEvil> I think in the case of a full-power 'event' they will be far enough from the rest of the airframe that it doesn't matter. :)
[23:08] <fuzzylugnuts> yeah, not everyone has that liberty
[23:10] <fuzzylugnuts> http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1507
[23:10] <fergusnoble> how easy is it to speed control an AC motor?
[23:10] <fuzzylugnuts> yeah, with a SCR
[23:10] <fergusnoble> do you have to change the frequency of the supply?
[23:10] <fuzzylugnuts> nope
[23:10] <fuzzylugnuts> it works similar to a light dimmer
[23:11] <fuzzylugnuts> though the inductive load might play havoc with it
[23:11] <fergusnoble> ok
[23:11] <fergusnoble> well i have a variac so that sould work
[23:11] <fuzzylugnuts> there you go
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[23:19] <fergusnoble> edmoore: not gone yet?
[23:19] <edmoore> not going
[23:19] <edmoore> having an early night and going out tomorrow
[23:19] <fuzzylugnuts> : (
[23:21] <edmoore> tess is up, y'see
[23:22] <fergusnoble> i see
[23:23] <edmoore> tomorrow, that is
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[23:24] <fuzzylugnuts> I wonder if I can get away with lithium thionyl chloride batteries
[23:24] <fuzzylugnuts> 200ma pulse current max
[23:24] <edmoore> I used them years and years ago
[23:24] <fuzzylugnuts> yeah?
[23:24] <edmoore> for tiny antweight robots
[23:25] <fuzzylugnuts> how'd they work?
[23:25] <edmoore> super duper
[23:25] <fuzzylugnuts> hmm
[23:25] <edmoore> thought crazily expensive, I remember
[23:25] <fuzzylugnuts> http://www.all-battery.com/index.asp?PageAction=VIEWPROD&ProdID=1507
[23:25] <fuzzylugnuts> about 10 bucks a pop
[23:25] <edmoore> and this was pre-lipoly so it might be like the swing you used to play on when you were 4 that is so much smaller when you visit it come adulthood
[23:26] <fuzzylugnuts> haha
[23:26] <fuzzylugnuts> might get a few for evaluation
[23:26] <fuzzylugnuts> 9Ah at 100g is hard to beat
[23:26] <edmoore> that's really really good
[23:26] <edmoore> 3.6V 9Ah 55g
[23:26] <edmoore> wow
[23:27] <fuzzylugnuts> yeah
[23:27] <edmoore> fergusnoble: look look look
[23:27] <fuzzylugnuts> super limited current drain though
[23:27] <edmoore> 200mA is enough for us
[23:27] <edmoore> sort of
[23:27] <edmoore> not
[23:27] <fuzzylugnuts> put a few in parallel
[23:27] <fergusnoble> nice
[23:27] <edmoore> i'm sure the ones I used were good for about 5C
[23:27] <fergusnoble> but we would need a boost regulator then
[23:28] <edmoore> two in series
[23:28] <fuzzylugnuts> yep
[23:28] <fergusnoble> could do
[23:28] <edmoore> -55 degrees too
[23:28] <fergusnoble> but then you would have to have 4 for the current
[23:28] <fuzzylugnuts> yeah
[23:29] <fuzzylugnuts> my stuff is pretty low current
[23:29] <fergusnoble> wow, pulse current still only 400ma
[23:29] <fuzzylugnuts> yeah
[23:29] <fergusnoble> the telit can draw 3A sometimes
[23:30] <fuzzylugnuts> 2 of those would power my tracker for 120 hours
[23:30] <fuzzylugnuts> the microtrak only transmits for 1/3s or so
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[23:31] <fuzzylugnuts> I'm only using them for the tracker because they are very well suited for that, but definatly something different for the gumstix and friends
[23:31] <edmoore> tadirans i used they were aa size but about $40 each
[23:31] <fuzzylugnuts> whoa
[23:31] <fuzzylugnuts> did they give you some sort of dizzying high?
[23:35] <edmoore> i think swo - ran little spinning cutting disks from 300 series motors off them
[23:35] <edmoore> antweights were fun
[23:35] <edmoore> this was when I was 13
[23:35] <fuzzylugnuts> cool, though
[23:35] <edmoore> got me into engineering
[23:35] <fuzzylugnuts> haha
[23:36] <fuzzylugnuts> oh, btw, the GIS guy at work said that the 60,000ft limit is just if its traveling really really fast
[23:36] <fuzzylugnuts> like a re-entering ICBM type fast
[23:37] <fuzzylugnuts> http://www.byonics.com/tinytrak/gps.php
[23:37] <fuzzylugnuts> and byonics came out witha cute little gps
[23:37] <fuzzylugnuts> the GPS3
[23:37] <edmoore> fuzzylugnuts: it's meant to be &&
[23:37] <edmoore> but often implimented as ||
[23:38] <edmoore> alt limit and speed limit
[23:38] <fuzzylugnuts> : (
[23:38] <fuzzylugnuts> that makes me a sad panda
[23:38] <edmoore> sirfIII based ones are &&, but have a software limit of 24km
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[23:39] <edmoore> for the estimation algoririthm
[23:39] <fuzzylugnuts> whaaaaaaaat
[23:39] <fuzzylugnuts> : (
[23:39] <edmoore> lassen iQ I tell you
[23:39] <Laurenceb> hehe
[23:39] <fuzzylugnuts> is that on sparkfun?
[23:40] <edmoore> yep
[23:40] <Laurenceb> yes
[23:40] <Laurenceb> theres one running nxt to me atm
[23:40] <edmoore> we use it on the badger board
[23:40] <fuzzylugnuts> I normally use the GPS-18-LVC, but its kinda heavy
[23:40] <fuzzylugnuts> I want to be spoogetasticly light
[23:41] <fuzzylugnuts> whoa.
[23:41] <edmoore> lassen is titch
[23:41] <fuzzylugnuts> 23ma
[23:41] <edmoore> it's a nice gps
[23:41] <fuzzylugnuts> hmm
[23:42] <fuzzylugnuts> OH
[23:42] <fuzzylugnuts> its a trimble!
[23:42] <fuzzylugnuts> we use trimble products at work, very expensive ones
[23:43] <fergusnoble> i third the vote of lassens are nice
[23:43] <fuzzylugnuts> I'll give 'em a shot
[23:44] <fuzzylugnuts> if I loose it all, thats minus ~400 for me
[23:44] <fuzzylugnuts> which is 2 days work for me.
[23:45] <fuzzylugnuts> which antennas do you guys use for the lassen?
[23:46] <fergusnoble> used the sparkfun one on the badger
[23:46] <fergusnoble> the sma one i mean
[23:46] <fuzzylugnuts> ah
[23:46] <fergusnoble> with the little lassen to sma adapter
[23:46] <fuzzylugnuts> ok
[23:46] <fuzzylugnuts> http://www.sparkfun.com/commerce/product_info.php?products_id=178
[23:47] <fuzzylugnuts> I might just keep them inside
[23:47] <fergusnoble> looks nice
[23:47] <fergusnoble> the sma ones has about 1km of cable attached
[23:48] <fuzzylugnuts> haha
[23:48] <fuzzylugnuts> heavy too?
[23:48] <fergusnoble> quite yeah
[23:48] <fergusnoble> has a plastic case around the antennay bit
[23:48] <fuzzylugnuts> the gps-18s were too
[23:48] <fuzzylugnuts> yeah
[23:51] <fuzzylugnuts> so if I sent up a SiRFIII, it would under-read the altitude?
[23:52] <fuzzylugnuts> has anyone done this yet?
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[23:57] <fuzzylugnuts> wb
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[23:59] <fuzzylugnuts> I need at least 2 strongbow's
[23:59] <fuzzylugnuts> *strongbows
[00:00] --- Sat Aug 16 2008