[00:22] <gordonjcp> http://www.pal-v.com/
[00:23] Nick change: Bluenarf -> EI5GTB
[00:26] <Laurenceb> the hell
[00:27] <Laurenceb> thats nutz
[00:28] <natrium42> very nice, how much?
[00:29] <SpeedEvil> Personal car-air-craft have been available for 80 years or so.
[00:30] <SpeedEvil> Or rather - have been going to be available in 5 years for 85 years, which surely must be the same thing.
[00:30] <Laurenceb> licensing is the issue
[00:31] <SpeedEvil> Control is an issue.
[00:31] <SpeedEvil> Noise is an issue
[00:31] <Laurenceb> and power use
[00:32] <Laurenceb> need zero point energy thrusters
[00:32] <Laurenceb> or antigravity
[00:32] <SpeedEvil> It's not _that_ bad.
[00:32] <SpeedEvil> You can do flying vehicles now - even electric ones.
[00:32] <SpeedEvil> Man-carrying.
[00:33] <SpeedEvil> Endurance - range is a big issue.
[00:33] <SpeedEvil> As is noise on takeoff, and fuel consumption
[00:33] <SpeedEvil> You get decent economy figures only if you can transition to a low-drag high-speed vehicle
[00:33] <Laurenceb> http://en.wikipedia.org/wiki/Eugene_Podkletnov
[00:34] <SpeedEvil> efficiently
[00:34] <SpeedEvil> http://en.wikipedia.org/wiki/Moller_Skycar_M400 http://en.wikipedia.org/wiki/Moller_Skycar_M400
[00:34] <SpeedEvil> for example
[00:36] <SpeedEvil> In the words of the SEC complaint, "As of late 2002, MI's approximately 40 years' of development has resulted in a prototype Skycar capable of hovering about fifteen feet above the ground.
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[00:44] <Laurenceb> heh
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[06:28] <natrium42> Laurenceb, OMG, i found the best ever camera stabilization system for ballooning --> http://www.youtube.com/watch?v=_dPlkFPowCc
[06:28] <natrium42> it's cheap too
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[08:38] <Laurenceb> hi
[08:39] <Laurenceb> natrium42: that chicken head thing was amazing
[08:39] <natrium42> :)
[08:40] <Laurenceb> almost like it was programmed
[08:41] <Laurenceb> head stays stationary until the neck reaches a point of maximum movement, then head jumps to a new position
[08:41] <Laurenceb> someone needs to do a proper experiment with a chicken on a robot arm
[09:01] <Laurenceb> SpeedEvil: about?
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[09:17] <Laurenceb> hi G8KHW
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[09:33] <G8KHW> yoyo Laurenceb - whats new?
[09:38] <Laurenceb> not a lot
[09:38] <Laurenceb> should have the UM12 test HAB ready by the weekend
[09:38] <Laurenceb> finally
[09:39] <Laurenceb> so if anyones flying, itd be cool to stick it on
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[10:50] <Laurenceb> http://www.student.montefiore.ulg.ac.be/~teney/index.html
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[11:08] <mc-> Laurenceb, do you have any experience with reading SD cards with AVRs?
[11:14] <Laurenceb> yeah, but only with a fat libaray
[11:14] <Laurenceb> from wehat ~I understand its quite easy
[11:14] <Laurenceb> see captin.at or whatever its called
[11:15] <Laurenceb> http://www.captain.at/electronic-atmega-mmc.php
[11:15] <Laurenceb> http://www.watzlavick.com/robert/rocket/ <- thought you might be interested in this
[11:18] <SpeedEvil> Laurenceb: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=516-1843-ND - 8DIP mouse sensor for a quid. fun.
[11:18] <mc-> thanks
[11:18] <Laurenceb> SpeedEvil: nice
[11:19] <Laurenceb> yeah hopefully I can finally get the UM12 test hab flown
[11:19] <Laurenceb> then I can think about how to improve the rogallo
[11:19] <Laurenceb> ideally ublox5 + two way radio + mouse sensor altimeter
[11:19] <Laurenceb> that would be insanely cool
[11:20] <Laurenceb> SpeedEvil: I was thinking a bit more about rockets - I think its worth making a nozzle with silica cloth
[11:21] <Laurenceb> silica cloth with epoxy resin
[11:22] <SpeedEvil> IIRC phenolic has lots better char properties, as does cotton
[11:22] <Laurenceb> I was looking at a few papers and silica cloth came out best
[11:23] <Laurenceb> epoxy is roughly equivalent to phenolic, but the cloth reinforces the char layer
[11:23] <mc-> how does a mouse sensor make an altitmeter?
[11:24] <mc-> *altimeter
[11:24] <Laurenceb> mouse sensor + some optics
[11:24] <Laurenceb> put it facing down then with some trig you can use the gps velocity to derive height
[11:24] <SpeedEvil> mouse sensor - mousepad is groun
[11:24] <SpeedEvil> d
[11:24] <SpeedEvil> LED is sun
[11:25] <Laurenceb> works pretty well for <100m
[11:26] <SpeedEvil> it also adds another (rapid) roll-pitch channel
[11:26] <mc-> and then tell the rogallo to flare for landing?
[11:26] <Laurenceb> well it'll turn into the wind
[11:26] <Laurenceb> theres no puitch control atm
[11:26] <Laurenceb> and building bearings for that would be hard
[11:27] <SpeedEvil> I was wonderin if you could lose the gyro
[11:27] <Laurenceb> maybe a telescopic front spar and linear actuator...
[11:27] <Laurenceb> nooo
[11:27] <SpeedEvil> I suppose low cloud would be a problem in that case
[11:27] <Laurenceb> as I have it it may as well be kept
[11:27] <Laurenceb> but ublox5 is pretty much good enough to do away with a gyro
[11:27] <SpeedEvil> I mean for future - a quid is much better than 15 - if it can be made to work
[11:28] <Laurenceb> I initially planned to use ublox4 and no gyro, but it wasnt good enough
[11:28] <Laurenceb> ublox5 seems to be considerably better behaved that 4
[11:28] <Laurenceb> *than
[11:28] <Laurenceb> actually... telescopic front spar isnt a bad idea
[11:29] Action: Laurenceb looks up linear acts
[11:29] <SpeedEvil> Also - shock absorber in front spar! :)
[11:29] <mc-> do airliners fly much above 45kft?
[11:29] <SpeedEvil> mc-: no
[11:30] <mc-> the js seems to be good in March at 45-60kft
[11:30] <mc-> would be easier to get permission if a HAB can stay above 45kft
[11:31] <mc-> I'll wait for jcoxon to come online
[11:31] <Laurenceb> mc-: for a crossing?
[11:32] <Laurenceb> I doubt that'll make a difference, we cant ensure the altitude is maintained
[11:33] <Laurenceb> hmm lin acts are expensive/unsuitable
[11:35] <Laurenceb> I wonder is a pneumatic rogallo would work
[11:36] <SpeedEvil> rack+pinion
[11:38] <Laurenceb> http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3043426#header
[11:38] <Laurenceb> heavy
[11:40] <SpeedEvil> and how do you do the source
[11:40] <Laurenceb> CO2
[11:40] <SpeedEvil> something like a lego rack and pinion
[11:40] <SpeedEvil> ah
[11:40] <SpeedEvil> valve is then the next problem
[11:40] <Laurenceb> CO2 + solenoid valve
[11:40] <SpeedEvil> s
[11:40] <Laurenceb> and nylon hose
[11:40] <SpeedEvil> and a servo to drive it
[11:40] <Laurenceb> no servos
[11:40] <Laurenceb> solenoid valves
[11:43] <Laurenceb> some stacking valve modules
[11:44] <Laurenceb> its how festo did some of their crazy flying stuff
[11:46] <mc-> yes, for a crossing. If it dropped to 45kft at night, how high would it go during the day?
[11:47] <Laurenceb> dunno, depends on the polythene
[11:47] <Laurenceb> maybe 60
[11:51] <Laurenceb> hmm with a single vertical poile going down from the wing to the electronics enclosure, and a universal joint connecting it to the wing, you could do roll and pitch with 2 cylinders
[11:51] <Laurenceb> problem is theres no feedback
[11:52] <Laurenceb> yeah pneumatic rogallo is probably a silly idea
[11:53] <Laurenceb> but it would look _very_ cool
[12:03] <Laurenceb> http://www.teamdavinci.com/understanding_pneumatics.htm
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[12:15] <SpeedEvil> depends on the size
[12:15] <SpeedEvil> for large - it's probably actually sane
[12:43] <Laurenceb> well servos work well for the time being
[12:49] <Laurenceb> http://www.davinciproject.com/news/timeline/balloon.php
[12:49] <Laurenceb> ^ interesting photos
[12:51] <Laurenceb> SpeedEvil: advantage of building an engine using silica fabric/epoxy overwrapped mold is that you can use better graphite throught shapes - they dont have to be able to slot in
[13:27] <SpeedEvil> throught?
[13:27] <SpeedEvil> oh
[13:28] <SpeedEvil> maybe
[13:28] <SpeedEvil> I'm unsure that you won't get near-instant charring, if you rely on that
[13:29] <SpeedEvil> with the graphite getting 'undercut' by the flowing gas through the charred layer at the back that you were hoping would attach - and the throat falls out.
[13:31] <Laurenceb> http://www.student.montefiore.ulg.ac.be/~teney/h2o2propulsion_aluminiumtank.htm <- this is interesting, but CO2 is stupidly heavy - works out at about 1.4 Kg extra mass per tube with my 7 tube launcher design compared to 130 grams of helium
[13:31] <Laurenceb> yeah
[13:31] <Laurenceb> I'm unsure how it would work
[13:31] <SpeedEvil> yeah
[13:32] <Laurenceb> theres a design in Sutton with an aluminium outer shell
[13:32] <Laurenceb> and the graphite is bolted in
[13:32] <Laurenceb> but thats heavy and adds complication to building it
[13:32] <SpeedEvil> easy, cheap, safe, high-performance, readily available. Pick any one.
[13:33] <Laurenceb> http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA307289&Location=U2&doc=GetTRDoc.pdf
[13:33] <Laurenceb> thats interesting
[13:33] <Laurenceb> pity that epoxy silica isnt as good
[13:33] Action: SpeedEvil is veging ATM.
[13:33] <Laurenceb> but it may be ok for my launcher design
[13:33] Action: SpeedEvil has just hedgetrimmed + shredded about 50Kg of hedge
[13:34] <Laurenceb> page 19
[13:34] <Laurenceb> :P
[13:34] <SpeedEvil> I wonder about basalt fibre.
[13:35] <Laurenceb> IIRC silica has higher melting point
[13:35] <Laurenceb> 2400C
[13:35] <Laurenceb> H2O2/kero burns at 2450C
[13:36] <Laurenceb> you can get hold of silica fabric firly easily
[13:36] <SpeedEvil> basalt is also easy
[13:37] <Laurenceb> appareltly the lamination technique is key
[13:37] <SpeedEvil> http://www.solarcomposites.com/composites/carbon fiber sleeves.html#BasaltSleeve
[13:37] <Laurenceb> you dont just wrap it around the mold or it delaminates
[13:37] <Laurenceb> you have to start at the top - by the injector and work down, so the fabric is at ~30 degrees to the gas flow
[13:38] <SpeedEvil> hmm
[13:38] <SpeedEvil> the above sleeves you can almost get there
[13:38] <Laurenceb> those regression rates are almost acceptable for my design
[13:39] <SpeedEvil> as the fabric is biaxial, and when stretched to a narrower diameter of tube, you get a strand orietnation approaching that
[13:39] <Laurenceb> about a 2mm increase in throught diameter
[13:40] <SpeedEvil> that's damn good
[13:40] <Laurenceb> over 30S burn time with epoxy/silica
[13:40] <SpeedEvil> that's wht - silica/epoxy?
[13:40] <Laurenceb> yeah
[13:41] <Laurenceb> from that paper
[13:41] <SpeedEvil> I wonder if any of the 'machinable ceramics' would be of use
[13:41] <Laurenceb> tensile strenght is important
[13:41] <SpeedEvil> yeah
[13:41] <Laurenceb> 500psi chamber pressure
[13:42] <Laurenceb> luckly silica is strong
[13:42] <Laurenceb> - relatively
[13:42] <SpeedEvil> where do you get quartz fibre though?
[13:42] <Laurenceb> 300gram approx for the 30cm long 70mm diameter engine
[13:43] <Laurenceb> http://www.topsealing.com/High%20Silica%20Fiber%20Cloth.htm
[13:44] <Laurenceb> "in severe application environments." lol
[13:44] <SpeedEvil> hmm
[13:49] <Laurenceb> I wonder if you could make a silica reinforced metal composite
[13:50] <SpeedEvil> umm
[13:50] <SpeedEvil> My _very_ limited knowledge says that aluminium will dissolve it rapidly at elevated temps
[13:50] <Laurenceb> yeah, you want something with low thermal conductivity
[13:51] <SpeedEvil> and limited conductivity and metals don't really go together:)
[13:51] <Laurenceb> epoxy is ideal as decomposition is endothermic
[13:52] <Laurenceb> some rough differential equations say you'll have around 3mm or epoxy intact after 30secs firing
[13:52] <Laurenceb> with 5mm initial wall thickness
[13:52] <Laurenceb> *of
[13:52] <Laurenceb> depends a lot of the epoxy - theres plenty of different high performance epoxies
[13:54] <Laurenceb> with epoxy/silica the char layer can still contribute to the tensile strenght of the chamber wall
[13:56] <Laurenceb> I wonder about a composite overwrapped copper liner
[13:57] <Laurenceb> -regen
[13:58] <SpeedEvil> I also wondered about CF/metal composite
[13:58] <SpeedEvil> it's really easy to do with electrodepostion
[13:59] <Laurenceb> yeah
[13:59] <Laurenceb> you electrodeposition idea would allow CF integration at the same time
[14:01] <Laurenceb> the problem is the fuel in the cooling channels is at much higher pressure than the nozzle
[14:01] <Laurenceb> it has to be strong
[14:01] <Laurenceb> smaller channels helps
[14:03] <Laurenceb> is electrodeposition with alloys possible ?
[14:04] <SpeedEvil> I did some tests - which looked promising - of taking a copper tube, wrapping square sections of conductive wax round it, and plating
[14:05] <SpeedEvil> this - if you start with a spun copper throat/chamber, place the square channels round it in a spiral almost touching, and then plate - seems plausible
[14:05] <Laurenceb> you could do two stage, first a "hollow" former plated with copper on the inside
[14:05] <Laurenceb> hmm ok
[14:05] <Laurenceb> I was thinking have the channels in the mould
[14:06] <SpeedEvil> then I was thinking probably simply use the electroforming to form teh walls of the cooling passages, machine the outside nice and smooth, then spin on a copper jacket
[14:06] <Laurenceb> or wrap with CF
[14:06] <SpeedEvil> yeah
[14:06] <Laurenceb> then stick int eh bath again :P
[14:07] <Laurenceb> only problem is copper isnt too strong
[14:07] <Laurenceb> really need some FEA to see if its all possible
[14:08] <Laurenceb> - tensile strenght vrs thermal conductivity
[14:08] <Laurenceb> but silica/epoxy certainly looks good
[14:13] <Laurenceb> http://www.cheshireribbon.co.uk/thermal_tapes.htm
[14:14] <Laurenceb> what was the site you linked earlier?
[14:15] <SpeedEvil> err
[14:15] <SpeedEvil> what site
[14:15] <Laurenceb> basaltic fibre
[14:15] <SpeedEvil> ah
[14:15] Action: Laurenceb is using irssi - no scrollback
[14:15] <SpeedEvil> ah
[14:15] <SpeedEvil> http://www.solarcomposites.com/
[14:16] <Laurenceb> nice
[14:18] <Laurenceb> yeah the basaltic isnt as good as silica
[14:18] <SpeedEvil> I'd remembered it as better than fibreglass
[14:18] <Laurenceb> hmm they mantion phenolic resin... I dont quite get it
[14:18] <SpeedEvil> but it's not as good as quartz
[14:18] <Laurenceb> I thought it was thermoset
[14:19] <SpeedEvil> it is, why
[14:19] <Laurenceb> so it comes as a resin?
[14:19] <Laurenceb> and its polymerised by high temperature?
[14:21] <Laurenceb> hmm ok... I get it
[14:22] <Laurenceb> so making a phenolic nozzle wouldnt be too hard, and phenolic/silica is even better than epoxy/silica
[14:23] <SpeedEvil> if you can get phenolic - I'm unsure
[14:23] <Laurenceb> itd be a pain to cure
[14:25] <Laurenceb> I dont get why the armadillo aerospace guys dont go for regen
[14:30] <Laurenceb> http://www.armadilloaerospace.com/n.x/Armadillo/Home/News?news_id=366
[14:34] <Laurenceb> its a pity they dont puit more info about the avonics, but they wnet for the throw money at it approach, and got an off the shelf strapdown IMU with fibre gyros IIRC
[14:35] <Laurenceb> they did have an attitude determining gps setup, but never seemed to get it running to correct drift in IMU attitude
[14:49] <Laurenceb> SpeedEvil: theres some tests where they've got better results using silica powder filler in the epoxy
[15:02] <SpeedEvil> was about to sugget that - it's a common filler
[15:02] <SpeedEvil> thixotropisic agent
[15:02] <SpeedEvil> also, I wonder about quartz microballoons - if you can get them
[15:03] <SpeedEvil> or agents with lots of water - gypsum
[15:08] <Laurenceb> hmm actually
[15:08] <Laurenceb> not sure if it helps - this was without quartz fibre
[15:09] <Laurenceb> you want to make the decomposition more endothermic
[15:09] <Laurenceb> but yeah microballoons may help by reducing conductivity... but epoxy is already an order of magnitude better than quartz
[15:10] <SpeedEvil> but it's not soild quartz
[15:10] <SpeedEvil> I dunno
[15:10] <fergusnoble> phenolic has etter high temp performance than most epoxies, but there are some specialist (read expensive) epoxies which can go even higher temp then phenolic
[15:11] <SpeedEvil> carbon-carbon composite, it's teh only way to go.
[15:11] <fergusnoble> even still the glass transition temp is never much more than 250C
[15:11] <SpeedEvil> All you need is some tar, which you can get cheap from builders merchant, and a reducing kiln at several KK
[15:11] <fergusnoble> yeah, carbon-carbon is the est thing
[15:11] <fergusnoble> i think you could do it yourself too
[15:11] <Laurenceb> hmm
[15:11] <SpeedEvil> I as thinking of that - it doesn't look _that_ hard.
[15:11] <Laurenceb> with your autoclave maybe
[15:12] <fergusnoble> the other option for a nozzle is graphite. its very easy to machine but makes a hell of a mess
[15:12] <fergusnoble> no, the autoclave only goes up to about 300C
[15:12] <Laurenceb> fergus: for my design its a lot heavier
[15:12] <fergusnoble> iain did an internship in a place that made carbon-carbon brakes for planes
[15:12] <Laurenceb> graphite is about twice the mass
[15:13] <fergusnoble> they heated them by passing a current through them and i think they were at aout 2000C
[15:13] <fergusnoble> but you could still do that with a gas fired kiln
[15:13] <Laurenceb> that paper I linked earlier is interesting- it seems that the difference in regression rates after a minute or so differs much less than over 30S or so
[15:14] <Laurenceb> epoxy isnt actually that much worse over 30S or so
[15:14] <fergusnoble> yeah, i think epoxy would be fine in terms of ablation
[15:14] <Laurenceb> phenolic takes longer to settle at a steady regression rate and ends up a lot better at around a minute
[15:14] <fergusnoble> the trouble is if the bulk heats up to a couple hundered degrees then you loose all structural intergrity
[15:15] <Laurenceb> but theres not a huge amount in it, <50%
[15:15] <fergusnoble> as the epoxy will turn back to being liquid
[15:15] <fergusnoble> well, jelly like
[15:15] <Laurenceb> yeah - for a 5mm wall its okay for 30s fine
[15:15] <Laurenceb> youd want to use high temperature epoxy
[15:15] <fergusnoble> for standard epoxy the temperatre is even less, more like 150C
[15:16] <Laurenceb> yeah... it really depends
[15:16] <Laurenceb> you can get a really sharp edged thermal wave moving through
[15:16] <fergusnoble> but like you say, its only for a short time
[15:16] <Laurenceb> so the outside is hardly heated
[15:16] <fergusnoble> so what is the application, jst a normal rocket motor nozzle?
[15:17] <Laurenceb> well nanosat launcher design I came up with
[15:17] <Laurenceb> based around 80mm CF tubes
[15:18] <Laurenceb> and H2O2/Kerosene
[15:19] <Laurenceb> anything with CF in it performs quite poorly from what I can find - thermal conduction along the fibres is bad
[15:20] <Laurenceb> carbon/carbon overwrapped silica phenolic is one option
[15:22] <fergusnoble> for our modified motor casings we are using this interesting low desity ceramic
[15:22] <fergusnoble> its less dense than cardboard
[15:22] <Laurenceb> are you going to remove the cardboard surrounding the fuel grain?
[15:22] <fergusnoble> but very insulating and can withstan large pressures without crushing
[15:23] <Laurenceb> hmm link ?
[15:23] <fergusnoble> probably not, just replace the aluminium tube
[15:23] <Laurenceb> ok
[15:23] <fergusnoble> can't rememer where we found it
[15:23] <Laurenceb> would it withstand erosion?
[15:23] <fergusnoble> probably not very well
[15:24] <Laurenceb> or is it quite powdery
[15:24] <fergusnoble> its a bit powdery
[15:24] <Laurenceb> hmm thats the thing with silica cloth, it withstands erosion wall
[15:24] <Laurenceb> *well
[15:24] <fergusnoble> but may be good for going between the nozzle and the cf body
[15:24] <Laurenceb> in my design theres an aluminium bulkhead/injector
[15:25] <Laurenceb> the nozzle bolts onto the bulkhead
[15:25] <fergusnoble> ok
[15:25] <SpeedEvil> umm
[15:25] <fergusnoble> of course your talking about a liquid rocket
[15:25] <Laurenceb> yes
[15:25] <SpeedEvil> oh
[15:25] <SpeedEvil> the bolts go all the way past the combustion chamber
[15:26] Action: Laurenceb searches for a diagram
[15:26] <Laurenceb> ~SpeedEvil: combination combuastion chamber and nozzle
[15:26] <fergusnoble> so all combustion is done in the nozzle
[15:26] <Laurenceb> yes, itd be quite long
[15:26] <Laurenceb> with a throut
[15:27] <SpeedEvil> ah - right
[15:27] <fergusnoble> how are you going to pump the fuel?
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[15:27] <fergusnoble> helium header tank?
[15:27] <SpeedEvil> Hampster driven turbopump.
[15:27] <Laurenceb> helium yes
[15:27] <Laurenceb> 2000psi in the ullage space
[15:27] <Laurenceb> ~500psi chamber pressure
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[15:27] <Laurenceb> 280ISP
[15:28] <Laurenceb> 1KG 100mm square cubesat to LEO
[15:28] <fergusnoble> hehe, thats 138 bar
[15:28] <fergusnoble> make sure its a strong tank
[15:28] <Laurenceb> 1mm wall CF tank would be strong enough
[15:28] <fergusnoble> and im not going anywhere near it :p
[15:29] <Laurenceb> heh
[15:29] <Laurenceb> with a safety factor of 3
[15:29] <Laurenceb> youd want to reduce the safety factor and use cheaper Cf of course
[15:29] <fergusnoble> my instinct would be to go for a bit more than 1mm ut yo may be right
[15:30] <Laurenceb> it has to be that thin to be light enough
[15:30] <SpeedEvil> Or temp and pressure-cycle it lots
[15:30] <SpeedEvil> A pressure washer may actually be about right for the first
[15:30] <Laurenceb> if you use the really good stuff (T grade? or something ) you could get away with 0.3mm
[15:30] <Laurenceb> but that thin and its not going to be consistent
[15:31] <fergusnoble> Laurenceb: it also relies on the manufacturing process eing spot on
[15:31] <Laurenceb> you can get 0.6mm wall thickness thatd do off the shelf
[15:31] <fergusnoble> yeah
[15:31] <Laurenceb> well theres a pretty large safety factor
[15:31] <Laurenceb> but youre paying more for that
[15:31] <fergusnoble> i recently got a quote for some tube to be custom wound and it was only £200 for a long length made to any spec
[15:31] <SpeedEvil> filliment winding is nice if you can do it
[15:31] <fergusnoble> down to 0.3mm
[15:31] <Laurenceb> works out ariound £500 per tank
[15:32] <Laurenceb> oh wow ok
[15:32] <Laurenceb> yeah its cheap
[15:32] <Laurenceb> yeah this was for 3.6m tanks
[15:32] <fergusnoble> and they would put in however many longitudinal and transverse layers as you wanted
[15:32] <fergusnoble> Laurenceb: diameter?
[15:32] <Laurenceb> then 7 of them for the entire vehicle
[15:32] <Laurenceb> 80mm
[15:34] <Laurenceb> it has to work out at 2Kg dry mass for each stage
[15:34] <Laurenceb> which is tricky
[15:34] <fergusnoble> ok thats light
[15:34] <Laurenceb> but doable
[15:35] <Laurenceb> you can get a bit heavier if you fill all the stages
[15:35] <Laurenceb> I was going for the 1st stage modules being ~60% full
[15:35] <Laurenceb> which makes the balloon smaller
[15:36] <Laurenceb> the central module (final stage) is 3Kg
[15:36] <Laurenceb> then a 1KLg satellite
[15:38] <SpeedEvil> what is the burn time again - for the long stages?
[15:38] <Laurenceb> ~30seconds
[15:39] <Laurenceb> I just took a look at quartz microballoons - they make it worse
[15:41] <SpeedEvil> just a thought
[15:42] <Laurenceb> marginal descrease in conductivity and big decrease in heat capacity
[15:42] <Laurenceb> also you lkose the endothermic decomposition
[15:43] <Laurenceb> thats what really gives you the performance with ablatives
[15:45] <Laurenceb> SpeedEvil: did you get a quote for 90% ? H2O2 ?
[15:46] <fergusnoble> hmm, is this a silly idea.. for active guidance instead of moving the nozzle or putting vanes in the flow, just introduce fuel into other areas of the nozzle using solenoid valves?
[15:47] <Laurenceb> sure, theres an indian launcher that does that
[15:47] <fergusnoble> oh really, people do that already?
[15:48] <Laurenceb> my design uses differential throttling of the seperate modules
[15:48] <Laurenceb> yeah, theres a nice section on it in Sutton
[15:48] <Laurenceb> but its rather inefficient
[15:49] <fergusnoble> how come, doesnt provide much moment?
[15:49] <Laurenceb> I reacon differential throttling then peroxide attitude control with 4 nozzles on the top of the central module
[15:49] <Laurenceb> you need a lot of injection to give a good thrust vector shift
[15:50] <fergusnoble> ok
[15:50] <fergusnoble> but your still burning the same amount of fuel so it shouldnt reduce the performance of the rocket right?
[15:50] <Laurenceb> it may just be optimal for my central stage tho...
[15:50] <Laurenceb> it burns much less efficiently
[15:51] <fergusnoble> ok
[15:51] <Laurenceb> you have to inject into the nozzle
[15:51] <Laurenceb> in fact it hardly burns at all
[15:51] <Laurenceb> if your lucky it vaporizes
[15:52] <Laurenceb> also it is useless after burnout
[15:52] <fergusnoble> ok, i need to go into town
[15:52] <Laurenceb> cya
[15:52] <fergusnoble> brb
[15:52] <Laurenceb> its nice to be able to control attitude after burnout, and before payload deployment
[15:54] <Laurenceb> of course there is another option, H2O2 - catalyst chamber - nozzle injectors
[15:55] <Laurenceb> that has the advantage of saving weight be avoiding need for attitude control nozzles
[15:56] <Laurenceb> and it'll use less H2O2 for attitude control
[15:58] <Laurenceb> possibly.... its only borderline
[16:03] <Laurenceb> http://books.google.co.uk/books?id=LQbDOxg3XZcC&printsec=frontcover&dq=sutton+rocket+propulsion+elements&client=firefox-a#PPA619,M1 <- figure 16-8, the fact that attitude control nozzles on the top will be further from the C of G than the main motor will tip the balance in favour of attitude control nozzles
[16:04] <SpeedEvil> Laurenceb: yes - I sent you a link
[16:05] <SpeedEvil> IIRC ~1000e for 6*40l
[16:05] <SpeedEvil> and 300e for one
[16:07] <Laurenceb> enough for 3 launches :P
[16:08] <Laurenceb> hmm somehting I didnt consider, you can use the ullage He in the tank for attitude control after burnout
[16:08] <SpeedEvil> hmm
[16:08] <SpeedEvil> suppose
[16:08] <SpeedEvil> mass is quite small
[16:08] <SpeedEvil> after burnout
[16:10] <Laurenceb> and you only want small shifts
[16:10] <Laurenceb> I guess that tips the balance in fabvour of injection
[16:10] <Laurenceb> depends if you want to try and re-enter the upper stage
[16:11] <Laurenceb> but it prob wouldnt be worth it
[16:12] <Laurenceb> engine would be toast (use it as a sheild), bottom bulkhead would probably be unsalvagable, CF tube would probably be heat danaged, top bulkhead not worth much... leaving only the electronics
[16:13] <Laurenceb> I think the upper stage module could be built for £1KK (n prize anyone :P)
[16:14] <SpeedEvil> upper stage module is what?
[16:15] <Laurenceb> the central one in the cluster
[16:16] <Laurenceb> - cluster of 7
[16:16] <SpeedEvil> oh - right
[16:16] <SpeedEvil> it's not much more than a standard tube + ellectronics
[16:16] <SpeedEvil> and valvey stuff
[16:17] <SpeedEvil> And if the INS is part of teh sat - also...
[16:17] <Laurenceb> yeah
[16:17] <Laurenceb> moving to injection means the bottom bulkhead is more complex
[16:17] <Laurenceb> but it lets you move all the CNC machining to one part
[16:18] <Laurenceb> the top bulkhead can be done on a lathe - may save money
[16:18] <SpeedEvil> One of the reasons I went with teh somewhat hacky single rotating vane in the exhaust
[16:18] <SpeedEvil> You really want to make the bulkhead injection mouldable, so you can get the cost down to a tenner per :)
[16:19] <SpeedEvil> I assume CF/epoxy doesn't like LOX temps?
[16:19] <Laurenceb> hmm it really wants to be aluminium alloy
[16:19] <Laurenceb> apparently it works
[16:19] <Laurenceb> but can only wiothstand about 4 cycles before it really starts to fall apart
[16:20] <SpeedEvil> hmm
[16:20] <Laurenceb> I'd presume a dramatic decrease is strenght
[16:20] <Laurenceb> even after one chilldown
[16:20] <SpeedEvil> A boiloff fed low-thrust stage with a tiny radiation cooled engine would be fun
[16:21] <Laurenceb> I'm guessing there are epoxy compositions that make it work a lot better
[16:21] <SpeedEvil> oxygen/propane maybe
[16:23] <Laurenceb> most of the attitude control is going to be at staging
[16:23] <SpeedEvil> yeah
[16:23] <SpeedEvil> for the first 'stage' that's pretty urgent
[16:23] <Laurenceb> + some for motor machining inaccuracy and ablation assymetry
[16:23] <SpeedEvil> for the successive ones, you can delay a bit
[16:24] <Laurenceb> youd ignite stage N+1 before stage n burns out
[16:25] <SpeedEvil> oh - right - you mean use the remaining ullage as the stage burns out to do all the attitude control as the next stage lights a bit assymetrically
[16:25] <Laurenceb> no
[16:25] <Laurenceb> only the central module has injection
[16:25] <SpeedEvil> ah
[16:25] <Laurenceb> first "stage" is four mopdules, throttled for attitude control
[16:25] <Laurenceb> oh !"£$$"£
[16:26] <Laurenceb> cant do attitude control on two axes when the second stage fires up
[16:26] <Laurenceb> unless the two second stage modules have injection
[16:27] <Laurenceb> they'd need two injection ports each
[16:27] <Laurenceb> that really adds to the weight
[16:27] <SpeedEvil> spin-stabiltiy?
[16:28] <Laurenceb> unless... you run nylon line out of the central module to the two either side
[16:28] <SpeedEvil> maybe not nylon :)
[16:29] <Laurenceb> it has to burn off when the central stage ignites
[16:29] <SpeedEvil> ...
[16:29] <Laurenceb> - rammed intot he injection ports in the central stages nozzles
[16:29] <SpeedEvil> You get lots of wierd backflows round the vehicle
[16:29] <Laurenceb> also as its burning off you have a period with undefined control response
[16:30] <SpeedEvil> weight shift starts to look good
[16:30] <Laurenceb> 4 extra solenoid valves + pipework is a lot of weight
[16:30] <Laurenceb> yeah
[16:30] <Laurenceb> involves shaking the payload about a lot
[16:30] <SpeedEvil> true
[16:31] <SpeedEvil> but you can do that a lot on the ground
[16:32] <Laurenceb> I wonder what happens if stages 2 and 3 ignite at the same time
[16:32] <Laurenceb> but stage 3 has a smaller engine with lower thrust
[16:33] <Laurenceb> kind of like strap on boosters
[16:33] <Laurenceb> lower upper stage mass is very good
[16:33] <Laurenceb> actually... that same fact measn injection on stage 2 doesnt hurt you as much
[16:34] <Laurenceb> need to run it thrugh me sim code... which I dont have here
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[16:51] <Laurenceb> oh well I've gtg, cya all
[16:52] <SpeedEvil> wave
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[17:09] Nick change: Fighter|sleep -> Fighter1405
[17:09] <Fighter1405> Hey all
[17:11] <Fighter1405> Both energizer and Radiometrix refused my request for free components :(
[17:14] <DanielRichman> :(
[17:14] <DanielRichman> on what grounds?
[17:15] <Fighter1405> No idea, both are just more automatic emails :p Energizer I don't think they even read my email, I may try to explain it more to Radiometrix
[17:15] <DanielRichman> You need to improve your blagging skills
[17:16] <Fighter1405> Seems so :(
[17:16] <Fighter1405> You wouldn't consider selling any of your stockpile would you?
[17:16] <DanielRichman> You'll have to ask sbasuita
[17:17] <Fighter1405> Sure
[17:17] edmoore (n=ed@pomegranate.chu.cam.ac.uk) joined #highaltitude.
[17:17] <Fighter1405> At least the price on the tx isn't too bad if they won't donate it
[17:19] <Fighter1405> Here we go:
[17:19] <Fighter1405> Dear Mr. Holmes,
[17:19] <Fighter1405> My name is Edward Uwaezuoke and I work in the Customer Service Department at Energizer-Wilkinson Sword. I recently received your email concerning our Lithium batteries.
[17:19] <Fighter1405> Thank you for taking the time to contact us. Unfortunately at this time we are unable to provide you with the Lithium batteries. If this does change I will gladly contact you.
[17:19] <Fighter1405> Sincerely
[17:19] <Fighter1405> Edward Uwaezuoke
[17:19] <Fighter1405> Consumer Service Executive
[17:19] <Fighter1405> Automated reply :(
[17:20] <edmoore> fergusnoble: hello
[17:25] <fergusnoble> edmoore: hi
[17:25] <fergusnoble> whats crackin?
[17:25] G8KHW (n=Steve@ joined #highaltitude.
[17:25] <edmoore> so I hear that it all went tits up (because I wasn't there, of course)
[17:25] <edmoore> i'm just about to start getting ready for trinity
[17:25] <fergusnoble> meh, was an unfortunate couple of mistakes in combination
[17:26] <fergusnoble> you heard about the sea recovery attempt then?
[17:26] <fergusnoble> how was nice?
[17:26] <Fighter1405> Sea recovery attempt? :o
[17:26] <edmoore> what were the couple of mistakes in combination?
[17:27] <edmoore> nice was nice (as the passport control man cracked about 4 times)
[17:29] <Fighter1405> What happened with the sea recovery fergusnoble?
[17:30] <fergusnoble> unfortunately the radio died by the time we got back up the coast in the boat
[17:30] <fergusnoble> was fun though
[17:30] <Fighter1405> Was it waterproof?
[17:30] <fergusnoble> edmoore: massive underfil and cutdown failure
[17:30] <fergusnoble> Fighter1405: not intentionally
[17:30] <edmoore> such is life
[17:30] <fergusnoble> it was in a polystyrene box
[17:31] <edmoore> battery failure is a big suprise though
[17:31] <Fighter1405> Wow ok, I'm amazed it survived at all
[17:31] <G8KHW> any idea why the cutdown failed?
[17:31] <edmoore> what caused the underfil fergusnoble?
[17:31] <fergusnoble> not really, it could have iced up given the wx conditions
[17:31] <fergusnoble> edmoore: im not sure, i didnt really get too involved with that bit
[17:31] <edmoore> oh i misread, thought they'd run out of juice
[17:31] <sbasuita> Fighter1405, hi
[17:31] <fergusnoble> i imagine underestimation of how much free lift was needed
[17:32] <edmoore> fergusnoble: i understand (with a lot of emphasis on the understanding bit)
[17:32] <sbasuita> Fighter1405, how many batteries do you need?
[17:32] <fergusnoble> it was run through burst2a but i didnt supervise
[17:32] <Fighter1405> Haven't calculated the requirements yet, 20ish?
[17:32] <sbasuita> Fighter1405, no problem, you can have them.
[17:32] <sbasuita> Fighter1405, whereabouts are you?
[17:33] <fergusnoble> did someone mention that burst2a breaks down at higher payload weights though?
[17:33] <Fighter1405> Cuffley, near potters bar
[17:33] <Fighter1405> That would be great :)
[17:33] <Fighter1405> I'll pay postage of course
[17:33] <sbasuita> cool
[17:33] <sbasuita> how are you going to pay?
[17:33] <Fighter1405> Thanks very much :)
[17:33] <edmoore> i've not come across burst2a
[17:33] <Fighter1405> Do you have paypal?
[17:33] <fergusnoble> G8KHW: the cutdown wasnt a pyro style one it was a resistor/nylon tie design
[17:34] <sbasuita> No
[17:34] <sbasuita> my dad does though
[17:34] <edmoore> cable tie?
[17:34] <Fighter1405> Could I do it that way? Would he let you?
[17:34] <fergusnoble> edmoore: maybe it was burst1a, iain mentioned burst2d so i guessed steve had made a new version
[17:34] <fergusnoble> *2a
[17:34] <edmoore> was it a cable tie?
[17:34] <fergusnoble> yup
[17:34] <fergusnoble> the sal design
[17:34] <edmoore> right, i'm off to trin
[17:35] <edmoore> see you all later
[17:35] <sbasuita> Fighter1405, should be fine
[17:35] <Fighter1405> Great, thanks so much
[17:35] <sbasuita> Fighter1405, I'm a bit busy at the moment but I'll sort something out later
[17:35] <sbasuita> no problem
[17:35] <Fighter1405> That's fine, let me know how much postage will be and the paypal address :)
[17:35] <fergusnoble> the target asc rate was 6-6.5 and the mission would have landed on dry land without needing a cutdown even if the asc was only 4m/s
[17:35] <Fighter1405> When you get time
[17:35] <sbasuita> will d
[17:35] <edmoore> fucking cable ties.
[17:36] <fergusnoble> then cutdown just in case we massively failed on the fill
[17:36] <fergusnoble> which it seems we managed to
[17:36] <fergusnoble> anyway, i should have supervised the filling, that was silly of me not to
[17:36] <edmoore> ok, well lesson's learned. again. and again.
[17:36] <fergusnoble> ut i had my hands full with the comms stuff
[17:37] <edmoore> maybe one day everyone will make the mistake and then people will stop thinking they know better just because they've not personally experienced failure x or y
[17:37] <fergusnoble> anyway, im not convinced of the sal design, much happier with a big load of explosives :)
[17:37] <fergusnoble> edmoore: i think it was an honest enough mistake
[17:37] <fergusnoble> just a shame
[17:38] <fergusnoble> we were pushing things a bit, a 1.5kg balloon is pretty borderline for a 3kg payload 6m/s asc rate
[17:38] <fergusnoble> but didnt have time to get a 3kg
[17:38] <edmoore> still, after all the emails about using untested cutdown designs in crucial roles. It's all for nowt really.
[17:38] <fergusnoble> edmoore: anyway, we retired badger1 in style
[17:39] <edmoore> that's true
[17:39] <edmoore> for that we can salute her
[17:39] <edmoore> she did us proud
[17:39] <fergusnoble> i wouldnt have flown if i thought the cutdown was critical
[17:39] <edmoore> yeah fair enough, the fille would have been a suprise
[17:39] <edmoore> what was the ascent rate?
[17:39] <fergusnoble> it was a backup in case of a fill cockup
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[17:41] <Laurenceb> back
[17:41] <edmoore> fergusnoble: just OOI, do you recall the ascent rate?
[17:41] <fergusnoble> edmoore: hehe 2.5-3
[17:41] <edmoore> oh good lord
[17:41] <fergusnoble> so close :)
[17:42] <fergusnoble> actually it may have been a bit higher than that
[17:42] <Fighter1405> Moral of the story, make sure you have enough helium?
[17:42] <edmoore> ok, well we're knocking off this batch of pyro cutdowns anyway this week, + badger cub (just scanned logs) so good work on that
[17:42] <fergusnoble> the wx was a bit wierd and i think the ascent rate picked up to just under 4 when it got above 5-6km
[17:42] <edmoore> after queens ball 2morrow i'm around basically
[17:42] <SpeedEvil> And that backups should always be treated with as much seriousness as the primary system maybe
[17:43] <fergusnoble> Fighter1405: we had plenty of He
[17:43] <fergusnoble> just a stupid miscalculation
[17:43] <Fighter1405> Ah I see, fair enough
[17:43] <fergusnoble> SpeedEvil: yup, this is a fair point
[17:43] <fergusnoble> although the design had been flight tested
[17:43] <Fighter1405> Does anyone know of anything similar to this for the UK? http://www.mologogo.com/
[17:43] <fergusnoble> so we had every reson to elieve it would work
[17:44] <edmoore> i thought it never fired
[17:44] <fergusnoble> on nova13?
[17:44] <fergusnoble> no the flight computer fired it
[17:44] <fergusnoble> it just failed mechanically in some way
[17:44] <edmoore> on the previous flight i mean
[17:44] <edmoore> 11
[17:44] <fergusnoble> no when we recovered it it had een fired
[17:45] <fergusnoble> it just didnt get recorded in the logs
[17:45] <edmoore> ok
[17:45] <fergusnoble> on nova 11 the cutdown itself worked fine
[17:45] <edmoore> i mean nova10
[17:45] <edmoore> the star tracker
[17:46] <fergusnoble> my wild guess is that seeing as it was raining so hard it could have collected some ice which would have made it take a lot longet to get up to melting temperature
[17:46] <edmoore> that flew one of the cable tie designs, but i (perhaps incorrectly) recall that it was never fired
[17:46] <fergusnoble> edmoore: cant remember what happened there, you may be right
[17:46] <edmoore> but one of the cable tie designs flew on 11 did it?
[17:46] <fergusnoble> i think it was never fired because the conditions were never met
[17:46] <fergusnoble> yup
[17:47] <edmoore> it wasn't fired though - I was there for the pickup on that one
[17:47] <edmoore> balloon was still very much attached
[17:47] <edmoore> unless the cable tie was dropping something else - i honestly don't recall
[17:47] <edmoore> e.g. a banana
[17:48] <fergusnoble> anyway, we have always joked about commandeering a boat so it was fun to actually do that just once
[17:48] <fergusnoble> edmoore: the cable tie was on one of the balloons i think, or maybe the ackup down to the payload
[17:48] <edmoore> ok. but we certainly need to clarify the flight qualification of that cutdown design
[17:48] <edmoore> ok
[17:48] <fergusnoble> anyway i think the flight logic was such that it never got triggered
[17:49] <edmoore> ok. anywoo, will discuss this with you over a pint in the next couple of days
[17:49] <fergusnoble> its a very difficult problem, cutdowns get exposed to a lot of wierdness that is hard to anticipate in ground testing
[17:49] <fergusnoble> edmoore: yup, sure thing
[17:49] <fergusnoble> badger cub is on the way too
[17:50] <edmoore> indeed, that's why I've often been the person loudly shouting that, often by myself
[17:51] <edmoore> anyway yes, beer time later. can't wait to see/help with delivering the baby
[17:51] <edmoore> so to speak
[17:51] <edmoore> re: cub
[17:51] <fergusnoble> yup, im only about half way through the design
[17:51] <edmoore> cool, will be at yours in a flash
[17:52] <edmoore> where flash = approx 1.5 days :)
[17:52] <edmoore> are you going to queens tomorrow?
[17:52] <fergusnoble> yup, well have fun a trinity
[17:52] <fergusnoble> yup, im a queens
[17:52] <edmoore> awesome
[17:52] <edmoore> ok, cya l8r
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[17:52] <fergusnoble> but will try not to make it a CUSF meeting :p
[17:56] <Fighter1405> Do mobile phone batteries work in near space?
[17:58] <KingJ> There is only one way to find out...
[17:58] <Fighter1405> I mean, previous phones that have been sent up - have they worked up there? :p
[18:06] <DanielRichman> You only get signal below ~1000-2000m because the network is designed to work on the ground only
[18:08] <Fighter1405> Yah, I'm fine with the signal. Just don't want the batteries in the phone to be destroyed
[18:08] <Fighter1405> I doubt they are rated for those temps
[18:10] <DanielRichman> True that. But phones have been flown before. Don't fly a nice phone - just get one you don't mind losing
[18:32] <sbasuita> Argh! Why do GCSE coursework markers insist you draw graphs by hand?
[18:32] Action: sbasuita goes for his first attempt at the line of best fit
[18:35] <KingJ> What? They want the line of best fit freehand?
[18:35] <sbasuita> The whole thing
[18:35] <natrium42> you'll be doing a lot more graphs by hand in calculus at university :P
[18:35] <sbasuita> ; O
[18:36] <sbasuita> And then they want me to extrapolate it and estimate a value
[18:36] <sbasuita> This is what computers are built for!
[18:36] <KingJ> When I had to do "by hand" graphs I was at least allowed a ruler
[18:36] <sbasuita> Well, it's a curvy best fit (melting points of alkali metals versus atomic number)
[18:36] <KingJ> ah
[18:36] <KingJ> ruler won't help much there
[18:56] Nick change: KingJ -> kingj
[18:59] Nick change: Fighter1405 -> Fighter|dinner
[19:00] Nick change: kingj -> KingJ
[19:04] <G8KHW> fergusnoble:thanks for the info on the cutdown - its good to know it wasn't a igniter based cutdown failure
[19:05] <G8KHW> te difference between burst1a and burst2a was that burst2a allowed 2 balloons to be used
[19:06] <G8KHW> but I removed it after the poor results with a 2 balloon flight tat we had
[19:06] <SpeedEvil> KingJ: you get bendy things that are designed for that
[19:06] <G8KHW> that
[19:08] <G8KHW> As for slow XABEN5/6 ascent rate - that wasn't really evident on XABEN7/8 so the only thing I will probably change in burst1a is to increase the KCI1500 cd to 0.3 from 0.25
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[19:42] Nick change: Fighter|dinner -> Fighter1405
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[20:14] <sbasuita> Watch until you get general idea of the rant then skip to 1:10 for the lulz http://www.youtube.com/watch?v=yYIfyDENTIY
[20:15] <sbasuita> Though it is mysteriously cut off early... maybe it is just his screensaver.... or I've been trolled.... or both....
[20:16] mc-_ (i=50aff276@gateway/web/ajax/mibbit.com/x-8101d0ac8fac3f13) joined #highaltitude.
[20:16] <Fighter1405> Looks staged to me
[20:20] <DanielRichman> Could be, but you see how the backlight on the LCD turns off, like it does when you switch from GUI mode to text mode (X to virtual termial)
[20:22] <sbasuita> He's live streaming right now: http://chris.pirillo.com/live/
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[20:23] <DanielRichman> Yeah um... what's he doing?
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[20:28] <Fighter1405> Anyone ever stuck anything like this on a balloon to find it when it lands? :p https://loc8tor.co.uk/Store/product/Loc8tor-Plus-Pack,153,110.aspx
[20:29] <SpeedEvil> a ty
[20:29] <SpeedEvil> toy
[20:29] <Fighter1405> Mhmm, 200 meter range isn't bad though
[20:29] <DanielRichman> Up to 183m /
[20:29] <DanielRichman> 600 feet (clear line of sight)
[20:30] <SpeedEvil> a good reciever with a yagi and a 10mW transmitter wil get you tens of kilometers line of sight
[20:30] <DanielRichman> exactly
[20:30] <Fighter1405> Fine =/ Just thought it looked a neat solution
[20:30] <Laurenceb> SpeedEvil: I've been playing with some sims... I dont think you need the balloon
[20:31] <SpeedEvil> Laurenceb: groundlaunch you mean
[20:31] <Laurenceb> yes
[20:31] <Laurenceb> problem is calculating the area for the drag calc
[20:31] <Laurenceb> its quite long and thin...
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[20:32] <G8KHW> Great Range - Up to 183m /
[20:32] <Laurenceb> what with?
[20:32] <Fighter1405> I only meant for if it was lost in a forest or so
[20:32] <SpeedEvil> Fighter1405: that's clear line of site
[20:33] <SpeedEvil> Fighter1405: it won't be as good as tht in a forest
[20:33] <Fighter1405> Never mind, it's too expensive for me to actually have considered anyway
[20:33] <SpeedEvil> Laurenceb: the problem then is the horribly thick atmosphere - you want to coast up at mach 0.8 or so for 30s or so. But that may only mean a couple more tubes
[20:34] <Laurenceb> it seems to work
[20:34] <Laurenceb> the thing is your through it quite fast
[20:34] <SpeedEvil> You can't be - drag goes up exponentially once you go past mach 1
[20:34] <Laurenceb> I've seen some results where it doesnt
[20:34] <SpeedEvil> well - it's _much_ worse at mach 2 than mach 1
[20:35] <Laurenceb> but it would require some tricky testing
[20:35] <Laurenceb> still, balloon at only 20Km is definately poss
[20:35] <SpeedEvil> I was using formulae I got from a NACA study on rocket dra that seemed appropriate for calculating drag coefficient
[20:35] <SpeedEvil> yeah
[20:35] <SpeedEvil> 20Km is past the worst of it
[20:36] <Laurenceb> http://aerorocket.com/validate.html
[20:38] <Laurenceb> bbl
[20:40] <sbasuita> Guys
[20:40] <sbasuita> http://www.ukhas.org.uk/ is down
[20:41] <sbasuita> DNS is not working for me
[20:41] <SpeedEvil> WorksForMe(tm)
[20:41] <sbasuita> :S
[20:41] <sbasuita> $ host ukhas.org.uk
[20:41] <sbasuita> Host ukhas.org.uk not found: 3(NXDOMAIN)
[20:42] <Laurenceb> noooo
[20:42] <Laurenceb> down for me too
[20:42] <DanielRichman> The wiki works
[20:42] <DanielRichman> sbasuita, host is working
[20:42] <sbasuita> someone broke the internets
[20:42] <sbasuita> or half of it
[20:42] <DanielRichman> Guess who's back
[20:43] <DanielRichman> it's back up?
[20:43] <SpeedEvil> ping www.ukhas.org.uk
[20:43] <SpeedEvil> PING ham.firshman.co.uk ( 56(84) bytes of data.
[20:43] <Fighter1405> www.ukhas.org.uk could not be found. Please check the name and try again.
[20:43] <Fighter1405> Down for me too
[20:43] <SpeedEvil> try that alias
[20:43] <SpeedEvil> ham
[20:43] <sbasuita> $ ping -c 1
[20:43] <sbasuita> PING ( 56(84) bytes of data.
[20:43] <sbasuita> 64 bytes from icmp_seq=1 ttl=48 time=83.9 ms
[20:44] <sbasuita> DanielRichman, alex is ordering stuff
[20:44] <sbasuita> DanielRichman, we just bought the 4gb EXTREME compactflash card
[20:44] <sbasuita> (over the normal one)
[20:44] <sbasuita> ; P
[20:44] <DanielRichman> sbasuita, have you made 100% sure that the bursar's office won't buy it aswell?
[20:44] <sbasuita> DanielRichman, no
[20:44] <sbasuita> DanielRichman, longshaft said to just buy it and give him receipts
[20:44] <DanielRichman> 'cause if they get off their ass and this stuff turns up, bad things iwll happen
[20:45] <DanielRichman> sbasuita, yes, but that doesn't mean that the bursars won't do it
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[20:45] <sbasuita> DanielRichman, yeh but it's his fault if they buy as well
[20:45] <AlexBreton> hi all
[20:45] <sbasuita> hello alex
[20:45] <DanielRichman> Just try and make sure!!!
[20:45] <AlexBreton> ordering schtuff
[20:45] <Fighter1405> http://www.youtube.com/watch?v=8IDWCXd8B_4
[20:45] <AlexBreton> space blanket now
[20:45] <DanielRichman> AlexBreton, about to PM you the past few lines of conversation
[20:45] <sbasuita> yay
[20:45] <sbasuita> AlexBreton, how big is the blanket?
[20:46] <AlexBreton> if it covers a person it'll cover our little box
[20:46] <DanielRichman> is that thing conductive?
[20:46] <AlexBreton> god knows
[20:46] <sbasuita> Fighter1405, love it
[20:47] <AlexBreton> it's made of metal
[20:47] <AlexBreton> covered in plasticky stuff
[20:47] <AlexBreton> BTW the price has dropped
[20:47] <Fighter1405> It's good :p
[20:47] <AlexBreton> 0.98
[20:47] <AlexBreton> as opposed to 1.17 last time
[20:48] <AlexBreton> sbasuita, the blanket is 2.15x1.3m
[20:48] <AlexBreton> order 1 or 2?
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[20:48] <sbasuita> can we cut it properly?
[20:48] <DanielRichman> OF COURSE we can cut it
[20:48] <AlexBreton> ofc
[20:48] <AlexBreton> 1 or 2?
[20:49] <AlexBreton> I assume we want gold for teh blingz
[20:49] <sbasuita> I can't imagine we'll need two
[20:49] <AlexBreton> ok?
[20:49] <sbasuita> no it is for insulation
[20:49] <sbasuita> go ask ##physics if you're not convinced
[20:49] <sbasuita> and it is not being spray painted!
[20:51] Action: sbasuita calls it a day on homework
[20:51] <sbasuita> time to put on some big beats and chill
[20:51] <AlexBreton> hmm
[20:52] <AlexBreton> apparently they sell space blankets down the road
[20:52] <sbasuita> AlexBreton, where?
[20:52] <AlexBreton> cotswold outdoor
[20:52] <sbasuita> AlexBreton, more expensive?
[20:52] <DanielRichman> AlexBreton, have you got polystyrene?
[20:52] <sbasuita> AlexBreton, you should probably go down and check out exactly what we're getting
[20:52] <AlexBreton> they're like a quid
[20:52] <DanielRichman> sbasuita, have you run bracknell metals?
[20:52] <sbasuita> DanielRichman, no
[20:52] <DanielRichman> do it now.
[20:52] <sbasuita> DanielRichman, bit late now isn't it?
[20:52] <DanielRichman> oh wait
[20:52] <DanielRichman> -.-
[20:53] <DanielRichman> Put the number into your mobile
[20:53] <DanielRichman> we'll do it at break
[20:53] <sbasuita> I'll do it on wednesday
[20:55] <sbasuita> http://www.qntm.org/?destroy
[20:55] <sbasuita> the whole site is great
[20:55] <sbasuita> but that page is just jokes
[20:55] <AlexBreton> hmmm cotswold's blankets are a fair bit pricier
[20:55] <AlexBreton> 3.50
[20:55] <AlexBreton> silver
[20:56] <AlexBreton> special camping stuff
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[20:56] <AlexBreton> what do you reckon? I'm ordering online
[20:56] <sbasuita> =/
[20:56] <sbasuita> Need to talk to somebody who has expert knowledge in the insulation/space business
[20:56] <sbasuita> ;
[20:57] <SpeedEvil> what're you wondering about
[20:57] <SpeedEvil> blanket?
[20:57] <AlexBreton> aye
[20:57] <AlexBreton> we have 2 rival blankets
[20:57] <sbasuita> hehe
[20:57] <AlexBreton> one is Gelert, 3.50
[20:57] <AlexBreton> silver
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[20:57] <SpeedEvil> what for
[20:57] <AlexBreton> the other is just generic, gold, 1 pound
[20:58] <AlexBreton> insulating the payload ;-)
[20:58] <sbasuita> SpeedEvil, this is space blanket for the outside of the payload
[20:58] <sbasuita> .wik space blanket
[20:58] <SpeedEvil> ah
[20:58] <herabot> "A space blanket, also known as a mylar blanket, first aid blanket or emergency blanket or weather blanket) is a blanket used in emergency situations to reduce heat losses in a person's body due to thermal radiation and convection." - http://en.wikipedia.org/wiki/Space_blanket
[20:58] <SpeedEvil> I know what they are.
[20:58] <AlexBreton> lol
[20:58] <sbasuita> that was for my benefit
[20:58] <Laurenceb> heh
[20:58] <AlexBreton> ofc
[20:58] <AlexBreton> so...
[20:58] <SpeedEvil> it's probably not really that critical
[20:58] <AlexBreton> I don't think there's much difference
[20:58] <SpeedEvil> most of the loss is by conduction as I understand it.
[20:58] <SpeedEvil> Do put it the right way round though :)
[20:59] <Laurenceb> SpeedEvil: it may just be possible to get to LEO using this design... but itd require some clever throttling during the ascent
[20:59] <AlexBreton> just the more expensive one can be bought in a store close to here
[20:59] <Laurenceb> if you launch off a tall mountain it helps... or a plane
[20:59] <sbasuita> AlexBreton, how much more expensive we talking?
[20:59] <AlexBreton> 2.50
[20:59] <AlexBreton> well less
[20:59] <DanielRichman> sbasuita, AlexBreton, SpeedEvil raises a good point. Will it really help?
[20:59] <AlexBreton> postage
[20:59] <AlexBreton> well it will
[20:59] <sbasuita> AlexBreton, we're going to expensive a few quid to the school?
[21:00] <DanielRichman> I mean, REALLY
[21:00] <AlexBreton> surely there can't be much conduction in the atmosphere
[21:00] <AlexBreton> in air I mean
[21:00] <sbasuita> its about radiation
[21:00] <AlexBreton> ye
[21:00] <sbasuita> we want to minimise loss of heat due to radiation
[21:00] <AlexBreton> and gold looks cool
[21:00] <SpeedEvil> AlexBreton: actually - conduction in air drops off annoyingly slowly
[21:00] <AlexBreton> really?
[21:00] <AlexBreton> well it reduces conduction too a bit
[21:00] <SpeedEvil> AlexBreton: basically as conduction is mediated by atoms hitting the surface and carrying away energy
[21:01] <SpeedEvil> for quite a while, though the number of atoms hitting is fewer - due to pressure - the increasing mean-free-path means that the thermal conduction stays pretty much the same
[21:01] <AlexBreton> makes sense ;-)
[21:01] <sbasuita> .wik mean free path
[21:01] <herabot> "In physics the mean free path of a particle is the average distance covered by a particle (photon, atom or molecule) between subsequent impacts." - http://en.wikipedia.org/wiki/Mean_free_path
[21:02] <AlexBreton> it reduces conduction too though
[21:02] <AlexBreton> mylar covered
[21:03] <DanielRichman> AlexBreton, the payload does not want your bling.
[21:03] <sbasuita> AlexBreton, the correct terminology is Biaxially-oriented polyethylene terephthalate
[21:03] <AlexBreton> OK have fun typing that
[21:03] <sbasuita> AlexBreton, just in case OCR decide to stop teaching brand namkes
[21:03] <AlexBreton> mylar for now
[21:03] <sbasuita> ; P
[21:03] <AlexBreton> so, space blanket, Yay or Nay?
[21:03] <sbasuita> DanielRichman, bling makes it easier to spot
[21:03] <sbasuita> obviously yay
[21:04] <AlexBreton> DanielRichman?
[21:04] <sbasuita> it's not like you lose anything by having it
[21:04] <DanielRichman> sbasuita, they would never! Their beloved GoreTex (TM)
[21:04] <DanielRichman> AlexBreton, nay
[21:04] <AlexBreton> hmmmmm
[21:04] <AlexBreton> 2 quid
[21:04] <AlexBreton> really
[21:04] <DanielRichman> deciding vote there.
[21:04] <AlexBreton> lol
[21:04] <AlexBreton> SpeedEvil, what would you recommend?
[21:04] <DanielRichman> Tensions rising
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[21:04] <sbasuita> jiffe, you have the final say
[21:04] <sbasuita> yay or nay?
[21:04] <DanielRichman> If you want, I can get you a good random number generator to pick it
[21:05] <jiffe> yay!
[21:05] <SpeedEvil> I don't seem to find a nice graph though
[21:05] <sbasuita> : )
[21:05] <DanielRichman> cock.
[21:05] <sbasuita> AlexBreton, order it now - push the button!
[21:05] <AlexBreton> waiting for the expert's opinion
[21:05] <SpeedEvil> AlexBreton: it doesn't matter much probably
[21:05] <SpeedEvil> AlexBreton: unless the gold is really yellow anodised aluminium
[21:05] <SpeedEvil> or brass or something
[21:06] <sbasuita> "coated with a metallic reflecting agent"
[21:06] <DanielRichman> sbasuita, add Fonts to the list of messed up things on linux/ubuntu
[21:06] <AlexBreton> wouldn't be gold
[21:06] <sbasuita> DanielRichman, never had a problem
[21:06] <AlexBreton> too expensive
[21:06] <sbasuita> ...
[21:06] <AlexBreton> argh this is annoying me
[21:06] <AlexBreton> we are just gonna paint it a day-glo colour
[21:07] <sbasuita> forget paint
[21:07] <sbasuita> if you want it to stand out space blanket is way easier
[21:07] <AlexBreton> DanielRichman, isn't high-viz paint the way to go?
[21:07] <DanielRichman> AlexBreton, no.
[21:07] <AlexBreton> what then?
[21:07] <sbasuita> AlexBreton, space blanket
[21:07] <AlexBreton> shaddap
[21:08] <sbasuita> AlexBreton, anything that goes up is covered in space blanket
[21:08] <AlexBreton> negative
[21:08] <DanielRichman> AlexBreton, I've written öfer in my german homework, and forgotten what it's meant to be. Any ideas?
[21:08] <SpeedEvil> IMO - size the polystyrene to cope witth -55C
[21:08] <SpeedEvil> and the heat load inside
[21:08] <SpeedEvil> do the numbers for that
[21:08] <SpeedEvil> and paint it flourescant orange
[21:08] <DanielRichman> quick, AlexBreton, use the U-value!
[21:08] <sbasuita> AlexBreton, http://soundofscience.files.wordpress.com/2009/03/gps_satellite_nasa_art-iif.jpg
[21:08] <sbasuita> it is gold
[21:08] <SpeedEvil> It's 0.04W/m/k for polystyrene
[21:08] <sbasuita> space blanket
[21:09] <sbasuita> i rest my case
[21:09] <sbasuita> ; P
[21:09] <sbasuita> alex loves his u-values
[21:09] <DanielRichman> SpeedEvil clearly knows his u-values
[21:09] <SpeedEvil> space blanket works _very_ well - in space
[21:09] <AlexBreton> yeah
[21:09] <sbasuita> Don't we need a certain type of polystyrene?
[21:09] <SpeedEvil> conduction doesn't drop off that fast
[21:09] <AlexBreton> there is no conduction there ;-)
[21:10] <SpeedEvil> hmm
[21:10] <sbasuita> (this is where the wiki comes in handy)
[21:10] <AlexBreton> http://www.wickes.co.uk/Polystyrene-Sheet/Polystyrene-Insulation-Board/invt/210823
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[21:10] <AlexBreton> sbasuita, we is buying that ;-)
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[21:10] <AlexBreton> 25mm thickness
[21:10] <AlexBreton> unless you want 50
[21:10] <sbasuita> nice and thick
[21:11] <AlexBreton> there is a wickes in reading
[21:11] <AlexBreton> I'll pick it up at the weekend
[21:11] <sbasuita> we might do 50mm
[21:11] <sbasuita> how much does it weigh?
[21:11] <AlexBreton> whatever
[21:11] <SpeedEvil> Aha!
[21:11] <DanielRichman> AlexBreton, get some 50mm for the outside, and 25mm to make parititons inside
[21:11] <AlexBreton> SD card module
[21:11] <DanielRichman> for all the bits
[21:11] <SpeedEvil> http://books.google.com/books?id=gfYolGeTePkC&pg=RA1-PA227&lpg=RA1-PA227&dq=MLI+insulation+pressure&source=bl&ots=aqB_ab9ieW&sig=yU4QGZ6vLY8QRaK2JlTB-T5bBZg&hl=en&ei=x6o2SsOpOZqUjAf40_34CQ&sa=X&oi=book_result&ct=result&resnum=3
[21:11] <DanielRichman> **partitions
[21:11] <AlexBreton> nom OK a sheet of each
[21:11] <AlexBreton> SD card module@
[21:11] <AlexBreton> !!
[21:11] <DanielRichman> libellium
[21:11] <sbasuita> SpeedEvil, translation into normal speak?
[21:11] <AlexBreton> which SD card module are we buying, the arduino one?
[21:12] <sbasuita> (tldr)
[21:12] <DanielRichman> there's a link on the wiki
[21:12] <SpeedEvil> sbasuita: At a ten thousandth of normal air pressure - conduction is only a tenth of that of normal pressure
[21:12] <sbasuita> right.
[21:12] <sbasuita> so are we going space blanket or not?
[21:13] <AlexBreton> no
[21:13] <SpeedEvil> After that, the conduction drops more or less proportionally with pressure
[21:13] <SpeedEvil> (which is way below the pressure up there - which is of the order of 1% of normal)
[21:13] <AlexBreton> AAAA!
[21:14] <AlexBreton> SD card module out of stock
[21:14] <G8KHW> do u mean convection?
[21:14] <SpeedEvil> G8KHW: no - conduction
[21:14] <SpeedEvil> I was contemplating using MLI for my house insulation.
[21:15] <SpeedEvil> Because I'm strange that way :)
[21:15] <SpeedEvil> (also because it would be 1cm, not 10cm thick)
[21:15] <SpeedEvil> But, you need quite nasty vacuums to make it work.
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[21:16] <AlexBreton> DanielRichman, we may have to wait a bit for the SD car module
[21:16] <AlexBreton> card*
[21:16] Action: SpeedEvil wants nice transparent aerogel glazing units.
[21:16] <SpeedEvil> SD card module
[21:16] <SpeedEvil> you mean just a connector?
[21:16] <AlexBreton> yeah
[21:16] <AlexBreton> think so
[21:17] <DanielRichman> AlexBreton, why?
[21:17] <DanielRichman> oh
[21:17] <DanielRichman> stock
[21:17] <SpeedEvil> I've soldered to them before.
[21:17] <AlexBreton> http://www.libelium.com/tienda/catalog/product_info.php?cPath=21&products_id=66
[21:17] <DanielRichman> no worries.
[21:17] <SpeedEvil> Alternatively, you can simply rip open a USB-SD reader
[21:17] <AlexBreton> I have one I think
[21:17] <AlexBreton> no it's CF reader
[21:18] <sbasuita> AlexBreton, call them up and ask when it is back in?
[21:18] <AlexBreton> it'll be in soon
[21:18] <AlexBreton> one of their top sellers
[21:18] <SpeedEvil> that looks like just pullups
[21:18] <sbasuita> AlexBreton, really?
[21:18] <AlexBreton> ye
[21:18] <AlexBreton> #3
[21:18] <AlexBreton> BTW
[21:18] <AlexBreton> for Alien 2
[21:18] <sbasuita> oh cool
[21:19] <sbasuita> here we go again...
[21:19] <AlexBreton> there appears to be a gas sensor pack available
[21:19] <sbasuita> I'm sure somebody already did atmosphere sampling
[21:19] <AlexBreton> detects gas, LPG, hydrogen, Methane
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[21:19] <DanielRichman> Alien #2 - the moon
[21:19] <SpeedEvil> there shouldn't be measurable amounts of that
[21:19] <SpeedEvil> That's no moon!
[21:19] <sbasuita> While we're speculating... alien2 will have a downwards facing camera and we're going to get night shots of london ;)
[21:20] <DanielRichman> Alien#2 invovles a visit to REAL space.
[21:20] <sbasuita> What we doing from an antenna standopint?
[21:20] <DanielRichman> sbasuita, ring bracknell metals
[21:20] <sbasuita> We putting a whip on top?
[21:20] <sbasuita> balloon man
[21:20] <AlexBreton> DanielRichman, how do you plan on getting to space in a balloon?
[21:20] <DanielRichman> ALIEN#2 - Land a payload on the moon. You know it makes sense
[21:20] <DanielRichman> AlexBreton, ROCKETS!
[21:20] <AlexBreton> errr.....no
[21:21] <AlexBreton> got some hydrogen peroxide?
[21:21] <DanielRichman> yeah, I drink the stuff
[21:21] <AlexBreton> shut up
[21:21] <AlexBreton> we're not going to space ;-)
[21:22] <DanielRichman> Yes we are! Come on, it makes sense
[21:22] <Laurenceb> heh
[21:22] <AlexBreton> sbasuita, DanielRichman, all OK on ordering the SD card module?
[21:23] <DanielRichman> Yes.
[21:23] <DanielRichman> (But it does make sense - think about it. None of the maintenance of a normal satellite, just land on the moon and profit?)
[21:23] <AlexBreton> you can't land on the moon
[21:23] <AlexBreton> face it
[21:23] <Laurenceb> SpeedEvil: I think you can do it without a balloon, if you can keep the drag coefficient around 0.5 below mach 2, you accelerate for a bit then keep it steady at around subsonic until you get above 10Km or so, then accelerate
[21:24] <AlexBreton> it took the US billions of dollars to do it
[21:24] <Laurenceb> 1st stage burns for about a minute
[21:25] <Fighter1405> You guys want to go to the moon now? :o
[21:25] <SpeedEvil> Laurenceb: for me, it looked optimal to keep it to below mach 0.8 at drag of 0.2 or so, to 10-15Km IIRC
[21:25] <Laurenceb> yeah same here more or less
[21:25] <SpeedEvil> then accellerate hard
[21:25] <Laurenceb> its verging on possible, but I'm not sure about optimal routes
[21:25] <Laurenceb> I'm guessing if I did proper sims it could be optimised
[21:26] <Laurenceb> not sure if the chamber would hold up for 1 minute
[21:26] <Laurenceb> need to look at the design properly with some finite element analysis
[21:26] <SpeedEvil> yeah - well, you could always go with more '0th' stage tubes
[21:27] <SpeedEvil> I even looked at little jet engines
[21:27] <Laurenceb> heh
[21:27] <SpeedEvil> which diddn't look entirely silly for stage 0
[21:27] <AlexBreton> guys, yagis are rather pricey
[21:27] <Laurenceb> a balloon isnt that bad
[21:27] <AlexBreton> sbasuita, DanielRichman
[21:27] <Fighter1405> How much for Yagis?
[21:27] <Laurenceb> to get to 20Km you could use a 15m diameter 100um envelope
[21:27] <AlexBreton> 110 pounds for a very nice one
[21:27] <sbasuita> told yu
[21:27] <SpeedEvil> 100um?
[21:27] <Laurenceb> thickness
[21:27] <Laurenceb> ie bloody though stuff
[21:27] <SpeedEvil> Laurenceb: I was wondering why so thick
[21:27] <sbasuita> AlexBreton, DIY job mte
[21:27] <SpeedEvil> ah
[21:27] <AlexBreton> sbasuita, call Bracknell bloody metals
[21:28] <sbasuita> AlexBreton, they're obviously closed
[21:28] <Laurenceb> SpeedEvil: easy to make
[21:28] <sbasuita> AlexBreton, i'm going to email the local ham club and ask if anybody has a 70cm yagi knocking about
[21:28] <SpeedEvil> ebaay has a wide selection of metal
[21:28] <SpeedEvil> Laurenceb: truue
[21:28] <Laurenceb> the helium gets expensive
[21:29] <Laurenceb> theres always solar thermal
[21:29] <SpeedEvil> That's what - 500m^2*100um = .05m^3 = 50Kg or so of plastic I suppose
[21:29] <Laurenceb> yeah
[21:29] <SpeedEvil> Or hydrogen
[21:29] <Laurenceb> solar thermal would be ~ an order of magnitude more volume
[21:30] <Laurenceb> so ~twice the diameter about 30m
[21:30] <SpeedEvil> I think you need to do a hell of a lot of FEA to convince me on the solar-tehrmal :)
[21:30] <Laurenceb> no solar heated balloon
[21:30] <Laurenceb> sorry
[21:30] <SpeedEvil> oh - right
[21:31] <Laurenceb> MIR as its known
[21:31] <SpeedEvil> that's lots more believable
[21:31] <Laurenceb> solar hot air balloon
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[21:34] <AlexBreton> sbasuita
[21:34] <DanielRichman> sbasuita, be sure to put bracknell metal's phone number in your phone please
[21:34] <AlexBreton> shipping from spain could take as long as 2 weeks
[21:34] <AlexBreton> shall I spec speedy delivery?
[21:34] <AlexBreton> seeing as it's out of stock as well
[21:34] <AlexBreton> school pays for it anyway ;-)
[21:34] <AlexBreton> OK?
[21:34] <sbasuita> AlexBreton, no
[21:34] <sbasuita> AlexBreton, normal delivery
[21:34] <AlexBreton> could take as long as month to arrive
[21:35] <sbasuita> AlexBreton, you said 2 weeks
[21:35] <AlexBreton> yeah but it's out of stock
[21:35] <sbasuita> AlexBreton, how much is the prices
[21:35] <AlexBreton> so as long as another 2 weeks for them to get it
[21:35] <AlexBreton> 18 euros for 24h delivery
[21:35] <AlexBreton> we get it very soon
[21:35] <sbasuita> how much for normal delivery
[21:35] <AlexBreton> dude, we're gonna have to start building this
[21:35] <AlexBreton> I'm going speedy
[21:36] <AlexBreton> normal is 8
[21:36] <AlexBreton> only 7 extra pounds
[21:36] <DanielRichman> AlexBreton, don't
[21:36] <AlexBreton> which we aren't paying
[21:36] <DanielRichman> you sure the school will like that?
[21:36] <AlexBreton> not our money!
[21:36] <sbasuita> AlexBreton, the school is going to rage if you piss their money up the wall
[21:36] <AlexBreton> he won't even check
[21:36] <DanielRichman> "not our money!" - You're doing it wrong.
[21:36] <AlexBreton> they'll get a total
[21:36] <AlexBreton> stop being so honest
[21:36] <AlexBreton> :P
[21:36] <sbasuita> AlexBreton, you have to give receipts
[21:37] <AlexBreton> sure
[21:37] <AlexBreton> we'll say standard delivery was that expensive
[21:37] <AlexBreton> which isn't totally improbable
[21:37] <DanielRichman> see if anything english resells it
[21:37] Action: Fighter1405 watches with amusement
[21:37] <AlexBreton> it doesn't
[21:37] <AlexBreton> checked
[21:37] <sbasuita> normal delivery
[21:37] <AlexBreton> you know how much we donate to the school every year?
[21:38] <AlexBreton> enough for 2 launches a year
[21:38] <sbasuita> AlexBreton, also ask the spanish guys how long till it is in stock
[21:38] <AlexBreton> so they had better allow
[21:38] <AlexBreton> it's closed
[21:38] <AlexBreton> can't wait for that sort of time
[21:38] <AlexBreton> and he won't know either
[21:38] <DanielRichman> AlexBreton, have you ordered anything today?
[21:39] <sbasuita> Guys there's no rush
[21:39] <sbasuita> just chill
[21:39] <Fighter1405> What's the metal for?
[21:39] <sbasuita> Fighter1405, building an antenna
[21:39] <sbasuita> for the receiving end
[21:40] <sbasuita> Fighter1405, http://www.fredspinner.com/W0FMS/CheapYagi/vjbcy.html
[21:40] <Fighter1405> Another attempt at building your own, eh>
[21:40] <Fighter1405> Surely you can build that last?
[21:40] <sbasuita> yep
[21:40] <sbasuita> ARGH somebody is ruining 100.0 FM on my radio
[21:40] <sbasuita> grrrr
[21:41] <DanielRichman> AlexBreton, if you've ordered anything today
[21:41] <DanielRichman> stop now.
[21:41] <DanielRichman> let us do it. You are not competent
[21:45] <AlexBreton> you failures can't internet shop to save your lives
[21:45] <AlexBreton> ordering Arduino SD card module, express delivery now
[21:45] <AlexBreton> total 36 euros
[21:45] <AlexBreton> all OK?
[21:45] <AlexBreton> sbasuita?
[21:45] <AlexBreton> DanielRichman?
[21:45] <Fighter1405> Oh it's the SD card module that needs the delivery?
[21:46] <AlexBreton> ye
[21:46] <natrium42> oooh --> http://www.youtube.com/watch?v=YsQb-oWq6d4
[21:46] <AlexBreton> from spain
[21:46] <sbasuita> AlexBreton, don't get the express delivery man
[21:46] <natrium42> balloon burst video
[21:46] <natrium42> from wb8elk
[21:46] <AlexBreton> what is your issue with speedy delivery?
[21:46] <DanielRichman> AlexBreton, NO!
[21:46] <AlexBreton> ^^
[21:46] <DanielRichman> AlexBreton, don't do it.
[21:46] <AlexBreton> explain the problem
[21:46] <DanielRichman> We will discuss tomorrow
[21:46] <AlexBreton> no, tell me now
[21:46] <DanielRichman> there's no rush, especially since it's not in stock
[21:46] <DanielRichman> 1) Waste of money
[21:46] <Fighter1405> very nice natrium42
[21:46] <DanielRichman> 2) School will disagree
[21:47] <sbasuita> oh wow
[21:47] <DanielRichman> 3) we must give receipts
[21:47] <AlexBreton> the school will be fine
[21:47] <sbasuita> balloon burst is v. cool
[21:47] <AlexBreton> seriously, 7 pounds extra
[21:47] <AlexBreton> 7!
[21:47] <AlexBreton> that's peanut
[21:47] <AlexBreton> s
[21:47] <DanielRichman> natrium42, that's so cool
[21:47] <DanielRichman> AlexBreton, you pay the £7 yourself then
[21:47] <natrium42> DanielRichman, yeah
[21:48] <Laurenceb> lol at related videos
[21:48] <sbasuita> "The Sims 3 Intro And Short Gameplay HD"
[21:48] <AlexBreton> it has to be launched before August preferably
[21:48] <sbasuita> get in
[21:48] <Laurenceb> http://www.youtube.com/watch?v=wtLPhYUZQg4&feature=related
[21:48] <AlexBreton> because it starts raining in August!
[21:48] <AlexBreton> so there is a rush
[21:49] <AlexBreton> don't forget the box can't come together without the sd card module
[21:49] <SpeedEvil> sbasuita: yup
[21:49] <Laurenceb> its the Cu spaceflight crew :P
[21:50] <AlexBreton> and without the box the balloon can't come...more delays...think about it
[21:50] <AlexBreton> it makes sense
[21:50] <AlexBreton> + speedy delivery is 1st class, much less chance of it getting lost
[21:50] <AlexBreton> especially from abroad
[21:50] <AlexBreton> all this for seven extra pounds of someone else's money
[21:50] <SpeedEvil> It's _my_ money.
[21:51] <SpeedEvil> (indirectly)
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[21:51] <Laurenceb> all that landed in the sea :-/
[21:51] <AlexBreton> what else needs to be bought
[21:52] <sbasuita> AlexBreton, don't do the express delivery
[21:52] <AlexBreton> you people perplex me to no end
[21:52] <Laurenceb> http://www.youtube.com/watch?v=03u8jRycEZY <- lulwut
[21:53] <AlexBreton> if it gets lost/delayed don't blame me
[21:53] <AlexBreton> going for standard
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[21:56] <AlexBreton> oh cock
[21:56] <AlexBreton> the payment page is in spanish
[21:56] <AlexBreton> damn
[21:57] <DanielRichman> AlexBreton, DON'T BUY NOW
[21:57] <DanielRichman> AlexBreton, just wait!
[21:57] <DanielRichman> We will talk tomorrow
[22:00] <AlexBreton> why?
[22:00] <AlexBreton> what do you want to discuss?
[22:00] <AlexBreton> do it now
[22:01] <AlexBreton> DanielRichman, I'm listening ;-)
[22:01] <DanielRichman> AlexBreton, I've got to go, and I don't trust you to do it properly
[22:02] <DanielRichman> You're the only one that wants to buy stuff now. Just wait another day, so we can be 100% sure we're buying the right stuff
[22:03] <AlexBreton> I have the list in front of me
[22:03] <AlexBreton> you are talking to someone who only buys food in a conventional shop ;-)
[22:03] <AlexBreton> now stop being a paranoid control freak please ;-)
[22:04] <DanielRichman> OK fine, Do what you want, but it's your fault, and please get normal delivery
[22:05] <DanielRichman> See you tomorrow
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[22:13] <hallam> http://web.mit.edu/~emin/www/source_code/pycodes/index.html this would be useful for the Next Generation Balloon Communicator
[22:14] <hallam> Laurenceb: I'm interested to know more about your experience frying patch antennas by touching them, wonder if it could explain some odd gps occurrences I've had - I've never been particularly careful with the bare patches
[22:14] <hallam> do you think it's static or what?
[22:14] <Laurenceb> hi hallam
[22:14] <hallam> hi :)
[22:14] <Laurenceb> yeah, the LNAs have poor esd protection
[22:14] <Laurenceb> as it muchs up the performance
[22:15] <Laurenceb> I've never fried any, but I've been warned by people who have
[22:15] <hallam> I'm guessing it's a pretty subtle failure
[22:15] <hallam> wonder if it continues to draw current
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[22:15] <Laurenceb> id guess it knocks out a fet or two
[22:16] <hallam> well, thanks for the heads-up, I wouldn't have guessed
[22:16] <hallam> (by heads-up I mean me stalking the #highaltitude logs)
[22:17] <Laurenceb> :D
[22:28] <Laurenceb> hmm this is interesting - I've got a pair of UM12 modules talking, but things are getting really screwed by RFI
[22:28] <Laurenceb> never had this problem with radiometrix modules
[22:30] <SpeedEvil> um12 is what - high bitrate?
[22:31] <SpeedEvil> whereas the rm are simple FM?
[22:31] <Laurenceb> thats a point
[22:31] <Laurenceb> 1.2Kbps
[22:32] <Laurenceb> also the I2C seems to be suffering - I'm running it at the max speed the ublox can take, and theres 2 cables to the module
[22:33] <Laurenceb> probably forming a current loop
[22:33] <Laurenceb> if I faff with the cables it seems to effect the performance
[22:33] <Laurenceb> I'm lining the inside of the enclosure with conductive foil
[22:37] <Laurenceb> hallam: do you know if theres a standard result for the optimum path to orbit for a rocket?
[22:38] <Laurenceb> - as in attitude vrs time or something similar
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[22:49] <SpeedEvil> alas not.
[22:49] <SpeedEvil> It depends on everything
[22:49] <SpeedEvil> Thrust, drag (while that's a factor) staging, ...
[22:50] <Laurenceb> yeah...
[22:50] <hallam> Laurenceb: there's an analytical optimum for gravity loss but not drag loss
[22:51] <Laurenceb> i see
[22:51] <hallam> and there are publicly available profiles for real launchers
[22:52] <Laurenceb> guess you could use monte carlo ?
[22:52] <hallam> I think you can probably use a gradient descent optimiser for a fixed configuration of launcher
[22:53] <hallam> I believe the delta-v versus trajectory curve is fairly flat at the optimum
[22:53] <hallam> about 9500m/s is a good rule of thumb for surface to LEO
[22:53] <hallam> with gravity and drag
[22:53] <SpeedEvil> Or something like a harmonic series
[22:53] <SpeedEvil> representing thrust angle
[22:53] <hallam> right
[22:54] <hallam> you can use the analytic solution once you're out of the atmosphere
[22:54] <hallam> which is where most of the flight and energy is
[22:54] <Laurenceb> this vehicle has delta v of 9375 atm
[22:54] <SpeedEvil> That's probably too tight
[22:55] <hallam> eh, you might pull it off
[22:55] <hallam> is that with no margin at all?
[22:55] <SpeedEvil> but who knows.
[22:55] <SpeedEvil> I was working on a delta-v of 12000m/s IIRC
[22:55] <hallam> they usually have a fairly substantial propellant margin on top of the traj requirement, to deal with off-nominal engine issues
[22:55] <Laurenceb> thats with 1Kg payload and engines at 85% theoretical isp
[22:55] <hallam> SpeedEvil: that's way more than necessary
[22:56] <SpeedEvil> hallam: I know. This was a _dumb_ launcher
[22:56] <hallam> right-angle trajectory?
[22:56] <Laurenceb> if you launch from 20Km, 9Km/s seems to be ok
[22:56] <hallam> Laurenceb: sure, especially if you have high thrust
[22:56] <SpeedEvil> hallam: not quite - simply that it was designed to survive - for example - a stage vastly underperforming.
[22:57] <hallam> ok
[22:57] <SpeedEvil> hallam: or having to recover from large errors imparted by a dodgy stage nav
[22:57] <Laurenceb> http://imagebin.org/52585
[22:57] <Laurenceb> oh yeah I added some margin for fuel used for injection
[22:58] <Laurenceb> oh that design is different- using attitude control on the central stage - I think injection into the nozzle will work better now, and ablative nozzles
[22:58] <Laurenceb> not sure if H2O2 or kerosene injection is best...
[22:59] <hallam> Laurenceb: drop that on the Arocket list and you'll probably get some useful feedback
[22:59] <hallam> and some useless feedback
[22:59] <Laurenceb> Arocket list?
[23:00] <Laurenceb> http://www.arocketry.net/ aha
[23:00] <hallam> http://lmgtfy.com/?q=arocket+list&l=1
[23:00] <hallam> ah i was too slow
[23:00] <Laurenceb> with H2O2 injection you may be able to add catalyst chambers between the solenoid valves and the injection ports
[23:01] <Laurenceb> that makes it more efficient, but adds dry mass
[23:01] <SpeedEvil> it also _vastly_ complicates things
[23:01] <SpeedEvil> as your attitude control is then dependant on the temperature andd condition of the catalyst pack
[23:02] <Laurenceb> yeah thats all firmware :P
[23:02] <Laurenceb> the hardware is fairly simple
[23:02] <natrium42> where is the james of coxons?
[23:02] <Laurenceb> with the queen of heart
[23:02] <SpeedEvil> adding yet another kalman filter to work out the attitude catalyst pack temps ...
[23:02] <Laurenceb> rofl
[23:02] <hallam> explain the engine concept?
[23:02] <Laurenceb> http://www.arocketry.net/hybrid.html ,-- ok these guys mean business
[23:03] <Laurenceb> well atm I'm thinking silica fibre / epoxy nozzle and chamber
[23:03] <hallam> kero/peroxide pumped by a spring?
[23:03] <natrium42> Laurenceb, nice, but... my eyes
[23:03] <hallam> yeah the arocket list bears little relationship to the website nowadays
[23:03] <Laurenceb> no, pressurised by helium
[23:04] <Laurenceb> its an off the shelf CF tube, with bulkheads
[23:04] <Laurenceb> basically
[23:04] <hallam> ok
[23:04] <hallam> what isp are you assuming?
[23:04] <Laurenceb> 280
[23:05] <Laurenceb> 260 effective when some propellant is used for thrust vector control
[23:05] <hallam> thrust?
[23:05] <Laurenceb> injection into the nozzle to shift the thrust vector
[23:05] <Laurenceb> anyway, theres a cluster of 7 of these stages, sharing the same design - like OTRAG
[23:06] <Laurenceb> the central one has a cubesat on the top
[23:06] <hallam> yeah what's the engine thrust?
[23:06] <Laurenceb> not sure yet
[23:06] <Laurenceb> may be less on the first stage modules
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[23:07] <Laurenceb> about 1.5KN
[23:07] <Laurenceb> firing for about 30 seconds
[23:07] <hallam> the concept passes my not-completely-ridiculous intuitometer
[23:08] <Laurenceb> the tubes are about 80mm diameter and 3.6m long
[23:08] <Laurenceb> it may have to be launched from a balloon... not sure
[23:08] <hallam> would recommend asking arocket for ballpark feasibility of the engine thrust-to-weight at that scale
[23:08] <Laurenceb> yeah
[23:08] <SpeedEvil> that's a hell of a fineness ratio
[23:09] <hallam> why don't you go fatter?
[23:09] <SpeedEvil> Mr Whippy!
[23:09] <Laurenceb> the bulkheads are heavy
[23:09] <hallam> sure but so's a long thin tube
[23:09] <Laurenceb> and CF tube is easier to source
[23:09] <hallam> but I guess you've optimised it
[23:09] <hallam> control is going to be annoying with something that slender though
[23:10] <Laurenceb> there will be a cluster or 7 when its in the atmosphere
[23:10] <Laurenceb> *of
[23:10] <Laurenceb> fires 4, then 2, then the remaining central tube
[23:10] <hallam> true
[23:11] <Laurenceb> when your firing 4 you may be able to control with throttling
[23:11] <SpeedEvil> What happens when you excite that thing with .5G sideways at the resonant frequency though
[23:11] <hallam> one tube on its own has 3 times the slenderness of ares 1, which is having a special test flight to test stability because it's slenderer than anything flown before
[23:11] <Laurenceb> its a bit slow but you could really hammer the motors are they are submerged in kerosene
[23:11] <Laurenceb> yeah but thats solid
[23:12] <hallam> sure, but solid is a good thing, no slosh
[23:12] <Laurenceb> so you have all sorts of pogo oscillations
[23:12] <SpeedEvil> err
[23:12] <hallam> pogo is more of an issue in liquid
[23:12] <SpeedEvil> solid doesn't do pogo
[23:12] <Laurenceb> yeah
[23:12] <hallam> solid does other nasty things that are similar to pogo
[23:12] <Laurenceb> doh
[23:12] <SpeedEvil> Or if it does, you have _way_ worseproblems
[23:12] <Laurenceb> theres quite a pressure drop across the injectors
[23:13] <Laurenceb> guess that helps?
[23:13] <hallam> I think you'll find you've underestimated mass pretty much everywhere
[23:13] <hallam> at least, that's the impression I get from watching / reading about people trying to do that kind of thing
[23:13] <hallam> just something to be aware of
[23:13] <Laurenceb> I've gone through it pretty well
[23:14] <hallam> what happens if you double the dry mass?
[23:14] <Laurenceb> it doesnt go anywhere
[23:14] <SpeedEvil> hallam: hence why I was shooting for 12000m/s
[23:14] <Laurenceb> even if you add ~infinite stages
[23:14] <Laurenceb> you need higher isp
[23:14] <hallam> try to make it work with double dry mass
[23:14] <Laurenceb> it wouldnt
[23:14] <Laurenceb> youd have to go with lox atl least
[23:15] <hallam> I had a spreadsheet rocket that would do orbit with 4-5 stages at 150s isp
[23:15] <Laurenceb> then tank design gets to be a pain
[23:15] <hallam> solids
[23:15] <hallam> yeah cryo is definitely best avoided if at all possible
[23:16] <hallam> especially with balloon launch
[23:16] <Laurenceb> I dont see where the mass is gong to come from - the CF tube is off the shelf
[23:16] <Laurenceb> the engine is tricky, but silica/epoxy looks good
[23:16] <hallam> engine, injector, staging, wiring, plumbing, fixings, adhesives
[23:16] <Laurenceb> way better than graphite
[23:17] <hallam> is the silica/epoxy supposed to ablate or just sit and take it?
[23:17] <Laurenceb> yeah staging would require some custom explosive bolts
[23:17] <Laurenceb> ablate
[23:17] <Laurenceb> theres papers with similar designs
[23:17] <hallam> that fucks the throat (which is the worst part thermally)
[23:17] <Laurenceb> yeah, but it stands up for about a minute
[23:17] <Laurenceb> at that size
[23:18] <hallam> really, without changing geometry? nice
[23:18] <Laurenceb> it erodes slowly at first
[23:18] <Laurenceb> then faster... its weird and depends on the epoxy used and tons of other stuff
[23:19] <Laurenceb> but its only a mm or so over 30S runtime
[23:19] <hallam> before posting on arocket you should probably produce a tabular summary of each subsystem with a terse description, performance and mass requirements - that will help people tell you which bits are feasible and which are big leaps
[23:19] <Laurenceb> infact the combustion temperature may not even melt the fibres
[23:19] <Laurenceb> yeah
[23:19] <Laurenceb> brb
[23:20] <Laurenceb> 2Kg dry mass per stage
[23:21] <hallam> I do think this is a really nice way to test the otrag idea at smaller/cheaper scale
[23:21] <hallam> there was good discussion recently on arocket about the merits of high performance suborbital tests
[23:21] <hallam> like maybe half the dV required for orbit
[23:21] <SpeedEvil> staging, ...
[23:22] <Laurenceb> brb
[23:22] <hallam> consensus was that they are almost always worth doing for development
[23:22] <SpeedEvil> vacuum performance, payload shrouds, ...
[23:22] <hallam> and that you shoul plan to recover for autopsy if possible, and if not then telemeter lots of things to learn plenty
[23:22] <hallam> i.e. don't even try for orbit on your first attempt
[23:22] <hallam> add mass for diagnostics
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[23:36] Nick change: KingJ -> kingj
[23:36] <Laurenceb> back
[23:36] <Laurenceb> yeah I allowed extra mass for stuff... just a sec
[23:37] Action: Laurenceb loads spreadsheet
[23:38] <Laurenceb> yeah fairing is 400grams, cubesat mount 200, IMU/computer 200
[23:38] <Laurenceb> 400 grams for the solenoids and pipes going down to the nozzle
[23:39] <hallam> batteries and wires?
[23:39] <Laurenceb> yeah... wires are light
[23:40] <Laurenceb> I alloowed 100 grams for each gearmotors - those have to have wireing to them
[23:40] <hallam> they traditionally add up to a surprising fraction of a spacecraft's mass (says SMAD), as does plumbing
[23:40] <Laurenceb> ideally youd have explosive bolts on the top bulkhead of each module
[23:40] <Laurenceb> then some sort of relase clip on the bottom
[23:41] <Laurenceb> havent come up with a workable design yet
[23:41] <Laurenceb> the fairing can be fixed to the stage 1 modules
[23:41] <hallam> yeah I am so scared of designing mechanisms
[23:42] <Laurenceb> you really want quadrature encoders on the gearmotors
[23:42] <Laurenceb> but thats not hard to source
[23:43] <Laurenceb> the bottom bulkhead would take some serious machining
[23:43] <Laurenceb> thats the one serious bit of machining work
[23:43] <hallam> CNC is cheap now
[23:44] <Laurenceb> yeah I looked up some quotes, hopefully ~$200 or so
[23:44] <Laurenceb> I'd aim for $1K for an entire tube module
[23:44] <Laurenceb> CF tube is astoundingly cheap
[23:45] <hallam> I think widespread cheap CNC is a quietly revolutionary enabling technology
[23:46] <Laurenceb> the bottom bulkhead has to incorporate fuel and oxidiser jets, ganged valves for fuel/oxidiser, fule and ox channels, and 4 solenoid valvues for the nozzle injection TVC
[23:47] <SpeedEvil> It'll enable skynet.
[23:47] <Laurenceb> oh and the CF tube and engine bolt into it
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[23:47] <SpeedEvil> Right now, it's quietly building parts in a thousand fab-shops all over the world.
[23:47] <SpeedEvil> And then shipping them to a disused warehouse.
[23:47] <Laurenceb> oh and the "coubling mechanism" for clustering the modules
[23:48] <Laurenceb> lol
[23:48] <SpeedEvil> and the payload
[23:48] <Laurenceb> thats the top bulkhead
[23:48] <Laurenceb> and nice and simple
[23:48] <Laurenceb> some CF honeycomb glues on or something
[23:50] <Laurenceb> silver decomposed H2O2 right?
[23:50] <hallam> yes but it's not necessarily the best catalyst
[23:50] <Laurenceb> I wonder if you could electroplate the pipes going down to the nozzle injectors with silver on the inside
[23:51] <Laurenceb> then use H2O2 for the injection
[23:51] <hallam> might or might not have enough surface area
[23:51] <Laurenceb> if it did, youd need to protect the holes in the nozzle
[23:51] <Laurenceb> or they'd act like mini hybrid motors
[23:54] <Laurenceb> maybe just stick stainless stell pipes through - ablation should be minimal in the nozzle area
[23:55] <Laurenceb> if you use decomposed peroxide instead of kerosene for the injection, its about twice as efficient
[23:55] <Laurenceb> also peroxide is denser than kero, so the penalty in tank volume is less
[23:56] <Laurenceb> also it works well for attitude control after burnout - very nice
[23:57] <Laurenceb> you could vent the helium as well to get a bit more pointing moment
[00:00] --- Tue Jun 16 2009