highaltitude.log.20090701

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[13:48] <edmoore> rjharrison: http://www.vimeo.com/5406970
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[13:58] <edmoore> hi RocketBoy
[13:58] <edmoore> we just got a toy delivered, think I'll bring it to EARS on sunday...
[13:58] <edmoore> http://www.vimeo.com/5406970
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[14:01] <RocketBoy> edmoore: are you planning to be on your own (this months launch will be the week after - if it goes ahead)
[14:03] <jcoxon> hey RocketBoy
[14:03] <RocketBoy> but that is a way cool camera
[14:04] <RocketBoy> yo jcoxon
[14:06] <jcoxon> hows it going?
[14:11] <RocketBoy> fine - I have bought a 2nd property (to rent out) - so I'm quite busy directing painters/plasterers/gardeneners/builders ...
[14:11] <RocketBoy> keeping an eye out for a JS weather window though
[14:12] <SpeedEvil> Ah. Buy to let.
[14:12] <SpeedEvil> I see you're keeping up with the times.
[14:12] <SpeedEvil> :)
[14:12] <jcoxon> RocketBoy, oh cool
[14:12] <jcoxon> today and tomorrow are good :-p
[14:12] <RocketBoy> I'm renting it to my daughter
[14:13] <RocketBoy> humm I'll think about tomorrow
[14:13] <SpeedEvil> Ah - slightly different then :)
[14:13] <jcoxon> let me run some sims
[14:16] <jcoxon> hmmm while the JS is quiet the ground winds are quite blowy
[14:16] <jcoxon> 8am launch lands you in the middle of leicester
[14:16] <RocketBoy> not cool
[14:17] <jcoxon> well i'll be free in a weeks time
[14:18] <jcoxon> :-)
[14:19] <RocketBoy> I bet you are looking forward to it
[14:20] <jcoxon> its a really tough exam next week but once its done - nothing till 5th october
[14:20] <jcoxon> (apart from going to work in africa for 6 weeks) :-D
[14:21] <RocketBoy> when are you leaving for africa?
[14:22] <jcoxon> i'm up in glasgow from 26th July till 13th August - infectious disease, then am going to Ghana on the 17th August till 3rd October
[14:23] <edmoore> RocketBoy: thanks for the tip
[14:23] <edmoore> I guess it'll be next week then
[14:23] <RocketBoy> ;-)
[14:25] <RocketBoy> I'll let you know if it is going ahead - the July meet is sometimes canceled due to crop spraying etc.
[14:27] <jcoxon> ive finally finished getting the gps and rtty working on my new board
[14:27] <jcoxon> :-D
[14:27] <RocketBoy> :-)
[14:28] <RocketBoy> whats your new board?
[14:28] <jcoxon> http://www.flickr.com/photos/jcoxon77/3662681108/
[14:29] <jcoxon> and i've attached a ublox gps to the serial port on the avr
[14:33] <RocketBoy> thats cool!
[14:34] <RocketBoy> what are people using now that the lassen IQ is discontinued?
[14:34] <RocketBoy> ublox?
[14:34] <jcoxon> i've got a ublox rcb-LJ (which is a 4) which i've used on one of my firefly missions
[14:35] <jcoxon> and i've got a ublox on my gumstix as well
[14:35] <jcoxon> and a spare lassen i
[14:35] <jcoxon> iq*
[14:35] <jcoxon> didn't know that they were now discontinued
[14:39] <RocketBoy> - I herad it the other day (not sure who it was from) - but that when current stocks run out that will be it - I guess i should check how true that is
[14:44] <RocketBoy> I was thinking of doing a PCB design - but was thinking of not using the IQ for that reason
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[14:59] <RocketBoy> bbl
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[16:03] <Laurenceb> hi
[16:07] <jcoxon> hey Laurenceb
[16:07] <Laurenceb> hi
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[16:23] <sbasuita> Snomi
[16:23] <Snomi> ohai
[16:23] <sbasuita> smells
[16:23] <sbasuita> wahey
[16:24] <sbasuita> Snomi, you going to the ib/alevel meeting tonight?
[16:24] <Snomi> nope
[16:24] <Snomi> mum is tho
[16:24] <Snomi> xD
[16:24] <Snomi> you?
[16:24] <sbasuita> Snomi, yeh
[16:24] <sbasuita> Snomi, gtaiv finished
[16:24] <sbasuita> Snomi, reboot ; )
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[16:26] <sbasuita> Snomi, heh, 10 mins to copy to vista XD
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[16:30] <jcoxon> sbasuita and co, hows the payload coming along?
[16:30] <sbasuita> jcoxon, got all the computer bits
[16:30] <sbasuita> jcoxon, so final testing on that
[16:30] <sbasuita> jcoxon, then thinking about how to bulid our payload
[16:30] <jcoxon> excellent
[16:31] <sbasuita> jcoxon, i think alex got a recommendation of celotex
[16:31] <sbasuita> jcoxon, so we'll probably make it out of that and reinforce with some thick cardborad
[16:31] <jcoxon> sounds interesting
[16:32] <jcoxon> i'm often just work with scrap polystyrene and hot glue
[16:32] <jcoxon> and lots of tape
[16:37] <Laurenceb> buy blue foam off ebay
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[16:46] <edmoore> jcoxon: it's show-off the new toy time
[16:47] <edmoore> http://www.vimeo.com/5406970
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[16:56] <jcoxon> oooo edmoore thats ooo cool
[16:56] <jcoxon> so very cool
[16:57] <edmoore> it's the best toy ever
[16:58] Action: jcoxon would like a space shuttle
[16:58] <jcoxon> but after that yes
[16:58] Action: SpeedEvil wants a rocket kit.
[16:59] <SpeedEvil> A few tons of prepeg epoxy, tanker of LOX/kero, filliment winder, ...
[16:59] <jcoxon> edmoore, got my flight computer working now
[16:59] <SpeedEvil> :)
[17:00] <jcoxon> just need to finish the cutdown device and we are ready to launch something :-)
[17:02] Action: Laurenceb would like to join in
[17:02] <Laurenceb> - UM12/ublox5 hab
[17:02] <Laurenceb> SpeedEvil: LOX + composities = not too good
[17:03] <jcoxon> Laurenceb, unfortunately i'm going for a floater
[17:03] <Laurenceb> ah ok
[17:03] <jcoxon> however you are welcome to fly the same day
[17:03] <Laurenceb> so your weight limited?
[17:04] <Laurenceb> hmm I dont trust it to fly by itself
[17:04] <jcoxon> wouldn't say my weight is limited
[17:04] <SpeedEvil> Laurenceb: that's what the tanker is for. You remove the wheels, and you've got a ready-made tank.
[17:04] <jcoxon> just there is a high failure risk :-p
[17:04] <SpeedEvil> :)
[17:05] <Laurenceb> heh
[17:05] <jcoxon> Laurenceb, perhaps hitch a lift with icarus
[17:05] <Laurenceb> yeah
[17:05] <edmoore> jcoxon: awesome news
[17:06] <edmoore> am looking forward to tracking it
[17:06] <jcoxon> now that i've moved off the breadboard etc the system is working very nicely
[17:07] <jcoxon> now the old chestnut that is the cutdown
[17:07] <SpeedEvil> You fill the chestnut with pyro?
[17:07] <Laurenceb> SpeedEvil: I made a sim with LN2 pressurization - even with three stages you need over 150Kg GLOW for it to work - ~35% of the mass is nitrogen
[17:07] <Laurenceb> it sucks
[17:07] <SpeedEvil> Ow.
[17:07] <Laurenceb> - dry mass
[17:08] <SpeedEvil> LOX pressurisation?
[17:08] Action: SpeedEvil ponders.
[17:08] <Laurenceb> heavier
[17:08] <SpeedEvil> yes - but burnable
[17:09] <jcoxon> Laurenceb, SpeedEvil, in regards to calculating an ascent rate (to decide whether to cutdown if now descending) do you think every minute sampling is appropriate?
[17:09] <jcoxon> as in calculate ascent rate from 2 alts a minute apart
[17:09] <SpeedEvil> You're I assume doing GPS constantly?
[17:09] <jcoxon> yes
[17:09] <Laurenceb> theres two options, gps velocity or gps altitude
[17:10] <SpeedEvil> I would probably try putting some smoothing in.
[17:10] <Laurenceb> simple way is altitudes a minute or so apart
[17:10] <SpeedEvil> Something like average each 10 seconds, and then compare t[-6] with now
[17:11] <jcoxon> i think a minute apart is fine
[17:11] <Laurenceb> are you using the solenoid valve?
[17:12] <jcoxon> this is just a vent flight
[17:13] <edmoore> jcoxon: we just wait to see if we get 10 downs in a row
[17:14] <SpeedEvil> sounds sane
[17:14] <jcoxon> edmoore, was thinking it would be helpful to see the drop in ascent rate as it vents helium
[17:14] <jcoxon> and once hte code is there it'll come in useful for later flights when we start trying to adjust the rate
[17:16] <Laurenceb> you want to carefully approach the neutral point
[17:18] <jcoxon> Laurenceb, the aim for this flight would be to see what happens with a vent, and the cutdown is to rescue it from going out to sea or if it becomes 'neutral' in heavy traffic airspace
[17:18] <Laurenceb> yeah
[17:18] <jcoxon> but in the future yeah
[17:18] <Laurenceb> hmm maybe just open the valve at say 10Km
[17:18] <Laurenceb> and see what ahppens to altitude
[17:18] <Laurenceb> but you should be able to model it pretty well
[17:19] <jcoxon> no valve on this one :-)
[17:19] <Laurenceb> hey?
[17:19] Action: SpeedEvil ponders ice-valve
[17:19] <SpeedEvil> bubble through water, which then freezes
[17:19] <SpeedEvil> actually - probably not
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[17:29] <Laurenceb> so, just a hole?
[17:29] <jcoxon> yup
[17:29] <jcoxon> its a replication of a flight that bill brown did
[17:29] <jcoxon> got him 17hrs aloft
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[17:44] <Laurenceb> SpeedEvil: lookup "Tridyne"
[17:45] <Laurenceb> its a liquid helium, lox, lh2 mix, passed over a catalyst
[17:48] <natrium42> ohai
[17:49] <jcoxon> hey natrium42
[17:49] <jcoxon> aren't you meant to be on a plane?
[17:50] <natrium42> jcoxon, flight to NYC is delayed by 1 hour
[17:50] <natrium42> might miss the plane to italy :S
[17:50] <natrium42> in toronto terminal atm
[17:50] <Laurenceb> http://www.dailymotion.com/video/xz7kf_snakes-on-a-plane-bring-it_fun
[17:50] <natrium42> ...
[17:52] <jcoxon> natrium42, oh rubbish
[17:52] <jcoxon> my grandparents are meant to be flying to the US today and have been delayed at heathrow
[17:54] <natrium42> let me guess, weather?
[17:54] <jcoxon> i assume so
[17:54] <natrium42> :S
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[18:41] Nick change: RocketBoy|Away -> G8KHW
[18:41] <Laurenceb> SpeedEvil: another idea - frozen peroxide solid motor
[18:42] <G8KHW> OK - I just don't understand IRC nickmakes - I have registered RocketBoy - how come someone else can use it
[18:43] <Laurenceb> hmm... I think anyone can login with the nick
[18:44] <Laurenceb> maybe you can chuck them... ask on #freenode
[18:44] <G8KHW> ta I will
[18:45] <SpeedEvil> on freenode?
[18:46] <G8KHW> NickServ
[18:46] <SpeedEvil> if so, you can register another nick - rocketboy_
[18:46] <SpeedEvil> and then group with rocketboy
[18:46] <SpeedEvil> ID as rocketboy_
[18:46] <SpeedEvil> ghost rocketboy, to kill the ID
[18:46] <SpeedEvil> then /nick rocketboy
[18:46] <Laurenceb> http://pdf.aiaa.org/preview/CDReadyMJPC06_1178/PV2006_4420.pdf
[18:47] <SpeedEvil> or maybe you can just /msg nickserv identify rocketboy mypassword
[18:47] <SpeedEvil> then /msg nickserv ghost rocketboy
[18:47] <SpeedEvil> I'm unsure
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[18:49] <Laurenceb> hmm frozen HTP would be stable on a balloon
[18:50] <Laurenceb> you could do an inverse hybrid
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[18:50] <Laurenceb> using propane
[18:52] <Laurenceb> once you get above ~5Km the frozen HTP wouldnt need coolin g
[19:05] <Laurenceb> yeah propane with a heater coil to raise the pressure, then a tube of frozen HTP at ~-8C below
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[19:09] <SpeedEvil> what's hte enthalpy of freezing, compared to combustion?
[19:09] <SpeedEvil> a percent or so?
[19:09] <Laurenceb> less
[19:09] <Laurenceb> tricky thing is freezing it in the first place
[19:09] <Laurenceb> it constracts
[19:09] <Laurenceb> blurg contracts
[19:10] <Laurenceb> maybe freeze the tube from the outside
[19:10] <Laurenceb> but youd need thermal blanket as a tube liner - as with any hybrid
[19:11] <SpeedEvil> Or ice
[19:11] <SpeedEvil> water ice
[19:11] <Laurenceb> too heavy
[19:11] <Laurenceb> you could form it in a cooled mould
[19:11] <SpeedEvil> prolly
[19:11] <Laurenceb> then load it in, but not sure how to retain it
[19:12] <SpeedEvil> thought was to lower the reaction rate to zero, so it'd stop eating at teh wall
[19:12] Action: SpeedEvil wonders at reaction rate of 50%H2O2 ice
[19:12] <SpeedEvil> recession rate
[19:13] <Laurenceb> wonder what the regression rate is
[19:13] <Laurenceb> it has been done
[19:13] <Laurenceb> well, not hybrid, but solid
[19:13] <Laurenceb> but the behaviour must be similar
[19:14] <SpeedEvil> waht's been done
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[19:14] <SpeedEvil> h2o2ice/something?\
[19:15] <Laurenceb> H2O2 ice, Polythene
[19:16] <Laurenceb> HDPE even
[19:16] <SpeedEvil> isp?
[19:17] <Laurenceb> cant find any data
[19:17] <Laurenceb> but it should be similar to the same hybrid design
[19:17] <Laurenceb> which gets about 330 theoretical in a vacuum
[19:17] <SpeedEvil> regression rate too high?
[19:18] <Laurenceb> dont know
[19:19] <Laurenceb> heat of fusion is 50% higher than paraffin wax
[19:20] <Laurenceb> so H2O2 with carbon black should have a slower regression rate
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[19:28] <Laurenceb> so about 2mm/sec
[19:35] Action: SpeedEvil ponders why that might be wrong.
[19:35] <SpeedEvil> does ice have a higher thermal conducctivity?
[19:36] <Laurenceb> I'm not sure thats important
[19:36] <SpeedEvil> probably not
[19:36] <Laurenceb> its the thermal transfer from the gas stream that limits the power/unit area I think
[19:36] <SpeedEvil> I suppose IR transmissivity is an issue
[19:37] <SpeedEvil> which I think is in H2O2s favour IIRC
[19:37] <SpeedEvil> though carbon black negates that somewhat
[19:37] <Laurenceb> you could add black yeah
[19:37] <SpeedEvil> err
[19:37] <SpeedEvil> carbon black on reflection may be a very bad idea
[19:38] <SpeedEvil> graphite powder?
[19:38] <Laurenceb> why is it a bad idea?
[19:39] <SpeedEvil> it has a huge surface area for reactions between the peroxide, and the carbon, or anything absorbed on it to occur
[19:39] <Laurenceb> yeah
[19:40] <Laurenceb> I'm not sure what the IR spectrum of H2O2 looks like
[19:44] <Laurenceb> http://www-691.gsfc.nasa.gov/cosmic.ice.lab/spectra.htm
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[19:46] <Laurenceb> fairly transpoarent
[19:49] <SpeedEvil> 400cm^-1 is only 2.5um though
[19:49] <SpeedEvil> what's the black body peak in the chamber - I suppose it's quite hot
[19:49] <Laurenceb> ~2800K
[19:51] <SpeedEvil> 2.5um and longer'll be what - only I suppose about a third
[19:51] <Laurenceb> about 3MW per square meter of surface
[19:51] <Laurenceb> IR emission
[19:52] <SpeedEvil> not much I suppose. 300W/cm^2
[19:52] <Laurenceb> hmm thatd melt 1cm/second
[19:52] <Laurenceb> somethings not right
[19:53] <SpeedEvil> that sounds out by an order of magnitude
[19:53] <Laurenceb> ~300J/gram to melt the ice
[19:53] <SpeedEvil> 1cm = 10l = 1/10th s per l
[19:53] <SpeedEvil> 300KJ per ...
[19:54] <SpeedEvil> maybe
[19:54] <SpeedEvil> I suppose that's why the black is needed in some form
[19:55] <Laurenceb> hmm the liquid layer absorbs the IR maybe
[19:56] <SpeedEvil> doubtful
[19:56] <Laurenceb> if one optical depth lies inside the liquid thickness
[19:57] <SpeedEvil> diddn't seem to bbe that strongly absorbing though
[19:58] <Laurenceb> it would give the right regression rate
[19:58] <Laurenceb> in wax they add ~3% by weight
[19:59] <SpeedEvil> If you're assuming that the only heating is IR, and it's all neatly evaporating, then you'll add the evaporation enthalpy too
[19:59] <SpeedEvil> And yes, reduce the rate
[19:59] <SpeedEvil> but not if droplets are ripped out of the surfaace without evaporating
[19:59] <Laurenceb> to about 1mm/sec
[20:00] <Laurenceb> yeah
[20:00] <Laurenceb> the only answer is that one optica depth is in the liquid
[20:03] <Laurenceb> I'm not sure if carbon black is dangerous in the solid state
[20:03] <Laurenceb> but yeah maybe when its mixed before freezing
[20:05] <SpeedEvil> graphite will be safer
[20:06] <SpeedEvil> simply as it's got less reaction surface
[20:06] <Laurenceb> yeah
[20:06] <SpeedEvil> by orders of magnitude
[20:06] <Laurenceb> and carbon black may have residue on it
[20:06] <SpeedEvil> yeah
[20:09] <Laurenceb> hmm tank needs to be ~50% longer but theres no liquid nitrogen
[20:10] <SpeedEvil> methane?
[20:10] <Laurenceb> nah propane
[20:10] <Laurenceb> then a heater coil to pressurise the tank to 600PSI
[20:13] <Laurenceb> thatd take about 400W
[20:13] <Laurenceb> only 80 grams with a 40C lipo
[20:15] <Laurenceb> interestingly with a CF tube tank you dont save anything by going to pumped propellants
[20:16] <Laurenceb> as on this scale you can make it work with ~0.7mm wall thickness, and if you go thinner with CF it seems to lose its integrity
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[20:26] <Laurenceb> bbl
[20:43] <sbasuita> G8KHW, you can set an option with NickServ to automatically rename anybody who doesn't authenticate after 30 seconds or so
[20:44] Action: sbasuita just got back from a presentation on IB
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[20:55] <SpeedEvil> sbasuita: IIRC that's not actually activated
[20:59] <DanielRichman> sbasuita, so, A level or International Baccalaureate?
[20:59] <sbasuita> SpeedEvil, well the school are offering it to us for our sixth form
[21:00] <sbasuita> DanielRichman, IB doesn't sound too bad
[21:00] <sbasuita> DanielRichman, certainly you get a bit more choice to do what you want to do
[21:00] <sbasuita> as in extended writing, CAS,e tc
[21:01] <DanielRichman> sbasuita, I'm A-level
[21:01] <DanielRichman> because of the Maths.
[21:01] <sbasuita> DanielRichman, you're still going for the maths?
[21:02] <DanielRichman> sbasuita, yes.
[21:02] <DanielRichman> Besides, you roll in more points for 5 A*s than 45 IB marks
[21:03] <DanielRichman> Grr... this is the only downside to slashdot. An interesting story gets assassinated by the webserver with the relevant video crashing under the load. :(
[21:03] <DanielRichman> Or maybe its internet connection... either way, it's dead
[21:07] <sbasuita> DanielRichman, you expect to average above 90% in every module?
[21:07] <DanielRichman> sbasuita, I'd like to... it's a target... besides, just as hard to get 100% in IB.
[21:07] <sbasuita> DanielRichman, what careers you looking at?
[21:08] <DanielRichman> Not entirely sure. But if I do Maths or Comsci at Uni, I will take the same A-Levels either way.
[21:08] <DanielRichman> I intend to start working somewhere in Computing - preferably high end programming, but I really don't know. What about you?
[21:09] <sbasuita> DanielRichman, I could see myself doing some sort of research work, ie. physics, computing/tech etc
[21:09] <DanielRichman> and you wanna do IB for that?
[21:10] <sbasuita> not sure
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[21:23] <sbasuita> How the hell does one chose a college?
[21:25] <SpeedEvil> sbasuita: nickserve, notIB
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[21:27] <sbasuita> SpeedEvil, oh right ;P What do you mean by activated?
[21:35] <SpeedEvil> sbasuita: working
[21:36] <SpeedEvil> sbasuita: work out which one will accept you, which have specialties or reputations in areas you're interested in, if any of the teaching staff are especially interesting, ...
[21:37] <SpeedEvil> And of course - financial
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[21:57] <jcoxon> hey all
[22:01] <Laurenceb> hi all
[22:02] <Laurenceb> sbasuita: college?
[22:03] <Laurenceb> you thinking of applying to oxbridge?
[22:03] <Laurenceb> hi hallam
[22:06] <DanielRichman> Laurenceb, (oxbridge) yes, would be nice.
[22:06] <Laurenceb> cool :P
[22:06] <DanielRichman> Did you read maths?
[22:06] <Laurenceb> yeah my approach to choosing colleges was to look at location, number of applicants per place, and tutors. But you've got a while to think about it yet :D
[22:07] <Laurenceb> physics - masters
[22:07] <DanielRichman> ahh, ok. Where?
[22:07] <Laurenceb> st hughs, oxford
[22:07] <DanielRichman> cool
[22:07] <DanielRichman> brb
[22:12] <hallam> hi Laurenceb
[22:14] <Laurenceb> hows it going?
[22:14] <Laurenceb> you finished now?
[22:16] <DanielRichman> About to go... but before I do, quick question. Any idea in which order Interrupts get serviced (ie, if more than one is waiting, which one goes first?)
[22:17] <Laurenceb> I think in order of address or something
[22:17] <Laurenceb> the priority is arbitrary
[22:18] <hallam> Laurenceb: yes all done
[22:18] <DanielRichman> Hmm. If it's in ascending order of address that looks like SPI will get attention before the UART. Damn
[22:18] <hallam> DanielRichman: try to make the interrupt service routines fast enough that it doesn't matter
[22:19] <hallam> i.e. they should take much less time than the shortest possible interval between interrupts
[22:19] <hallam> try to never put a delay in an ISR
[22:19] <DanielRichman> Don't worry, they're insanely fast, what I'm worrying about is that the SPI clock freqeuncy might be so fast that when sending a 200-byte message, forex, a gps character will be missed
[22:19] <DanielRichman> no delays in my ISRs :)
[22:19] <hallam> what's the SPI to?
[22:19] <DanielRichman> SD Card
[22:20] <DanielRichman> in theory should be fine, I'm just paranoid
[22:20] <hallam> the 200 bytes should be irrelevant - there will only be problems if the ISR takes longer to execute than the SPI peripheral takes to send a single byte
[22:20] <Laurenceb> yeah
[22:20] <Laurenceb> it'll service the uart inbetween
[22:20] <hallam> even at 10MHz that's a whole microsecond
[22:20] <DanielRichman> Indeed....
[22:21] <DanielRichman> at f/128 for the SPI, that still fast enough to transfer data, but one byte will take 1024 clocks, which is easily enough for both ISRs to run, I think
[22:21] <Laurenceb> http://www.youtube.com/watch?v=Wo-gGes6qig <- lmao (slightly NSFW)
[22:21] <Laurenceb> whats the arrangement with the UART?
[22:21] <Laurenceb> GPS?
[22:22] <DanielRichman> yes
[22:22] <DanielRichman> And I think they're double buffered too
[22:22] <jcoxon> hey henry
[22:23] <Laurenceb> ewwwww
[22:23] <SpeedEvil> http://cgi.ebay.co.uk/PAIR-OF-145mm-x-16mm-PERSONAL-ORGONE-BEAMERS_W0QQitemZ250218991976QQcmdZViewItemQQptZLoose_Gemstones?hash=item3a4236d168&_trksid=p3286.c0.m14&_trkparms=65%3A12|66%3A2|39%3A1|72%3A1683|240%3A1318|301%3A0|293%3A1|294%3A50
[22:23] <SpeedEvil> Is this the most bogus thing on ebay?
[22:23] <DanielRichman> anyway
[22:23] <DanielRichman> gtg now
[22:23] <Laurenceb> use TSIP and process it in the isr
[22:23] Action: SpeedEvil was looking for x-ray tubes..
[22:24] <Laurenceb> lmao
[22:24] <Laurenceb> COSMIC SUPERIMPOSITION and ETHER, GOD AND DEVIL.
[22:24] Action: Laurenceb defeats all with the Michelson moorley experiment
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[22:34] Nick change: G8KHW -> RocketBoy
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[22:41] <Laurenceb> http://www.youtube.com/watch?v=kNWfqVWC2KI
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[23:24] <Laurenceb> hmm three stage H2O2 ice hybrid works
[23:25] <Laurenceb> kind of horrible to assemble and store tho
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[23:34] <SpeedEvil> Not in the arctic!
[23:34] <Laurenceb> http://www.youtube.com/watch?v=UZt2_kqoqqI
[23:35] Action: SpeedEvil does not click youtube ATM - it's annoying to download when connection is going at 350k
[23:36] <Laurenceb> interestingly the 7 module design is the most practical still
[23:37] <Laurenceb> it seems to be down to more smaller engines being lighter
[23:38] <Laurenceb> also 1000psi tubes with pressurised ullage adds relatively little weight if its the right distribution of fibre directionality
[23:38] <SpeedEvil> hmm
[23:39] <SpeedEvil> how are you computing the 400W heater power?
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[23:39] <Laurenceb> to boil enough propane to fill the ullage space in the propane tank
[23:39] <Laurenceb> over ~30 seconds
[23:40] <SpeedEvil> oh - it starts out liquid?
[23:40] <Laurenceb> liquid propane in a tank above the H2O2 ice
[23:41] <Laurenceb> then you turn on the heater to raise the pressure, it bursts a cover and goes through the injector
[23:42] <SpeedEvil> don't you need to raise the temp of the whole tank, or use a membrane.
[23:43] <Laurenceb> the heater will be a coil at a few hundered degrees
[23:43] <Laurenceb> so there will be a load of bubbles
[23:43] <Laurenceb> and they will partically condense
[23:44] <Laurenceb> it'll be fairly complex....
[23:45] <Laurenceb> maybe a 20% overhead on the energy just to vapourise
[23:46] <Laurenceb> http://www06.wolframalpha.com/input/?i=propane
[23:46] <Laurenceb> the tricky thing is stabilising and supporting the H2O2
[23:48] <SpeedEvil> One man, and only one man can help you.
[23:48] <SpeedEvil> np: Vanilla Ice - Ice Ice Baby.mp3
[23:49] <Laurenceb> lol
[23:50] <SpeedEvil> I think a glued ceramic blanket, and set up the ice on that should work well
[23:50] <SpeedEvil> if the blanket can take the weight
[23:51] <Laurenceb> not sure
[23:52] <Laurenceb> the burn through will be patchy
[23:52] <Laurenceb> and you want to burn off all the peroxide without overheating the carbon fibre
[23:53] <SpeedEvil> hmm
[23:56] <Laurenceb> maybe a blanket, then some sort of inpermiable membrane with permiable stuff on one side
[23:56] <Laurenceb> to bond into the ice
[23:57] <Laurenceb> hmm paper soaked in peroxide... explosive?
[00:00] --- Thu Jul 2 2009