highaltitude.log.20091112

[00:04] <SpeedEvil> I'd consider vertical
[00:05] <SpeedEvil> from +15 to -35 or so
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[07:34] <jcoxon> morning all
[07:34] <bt42> hello
[07:36] <jcoxon> hey bt42
[07:41] <jcoxon> perhaps a spudnik1 launch today :-s
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[07:44] <MikeMc> morning
[07:45] <MikeMc> shame he has no radio on it though as we can't try to track it
[07:47] <jcoxon> indeed
[07:47] <jcoxon> oh well i wish them luck
[07:47] <jcoxon> MikeMc, any progress with your payload?
[07:48] <MikeMc> Not really i'm afraid - i've recently had a huge amount of orders on my online store to process and now i've had another order of 100 kits from my distributor so this is taking up all of my spare time right now trying to clear the backlog
[07:48] <MikeMc> i'm hoping that Sunday will be quiet and I can concentrate on doing some tests then
[07:49] <jcoxon> cool cool
[07:49] <jcoxon> i'm really tempted by your 8x32 led display boards
[07:49] <jcoxon> for mission control style flight timers etc.
[07:50] <MikeMc> they are really cool - and easy to control
[07:51] <jcoxon> a project for another time
[07:51] <jcoxon> got to get this payload finished
[07:51] <MikeMc> of course
[07:51] <MikeMc> looking forward to it
[07:52] <jcoxon> have ordered a pump to perhaps use with the ballast instead of a valve
[07:56] <MikeMc> your going for a stamina flight yes?
[07:58] <jcoxon> its a bit wierd - we need to test the ballast tanks in advance of a trans- a mission
[07:58] <jcoxon> so we need to get them up in the air and working
[07:58] <jcoxon> so we'll do a floater flight but then we'll mess it up by dumping ballast after a bit of time
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[08:49] <jcoxon> http://sites.google.com/site/qrptracker/home
[08:50] <jcoxon> quite cool
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[10:14] <gordonjcp> looks interesting but it's pretty light on content
[10:15] <gordonjcp> I haven't got enough of an attention span to watch the video
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[11:19] <Jon_Apex> any news on spudnik?
[11:25] <Randomskk> their website hasn't been updated sadly
[11:31] <Randomskk> Jon_Apex: the peltiers are on fedex vehicle out for delivery as of 9am this morning
[11:32] <Randomskk> fedex.com tracking # 413542357215 or http://boxoh.com/?t=413542357215
[11:36] <Jon_Apex> cool cool
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[12:32] <MikeMc> afternoon all
[12:37] <Jon_Apex> hello
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[12:37] <Laurenceb> hi
[12:38] <MikeMc> any potatoes in space yet?
[12:38] <Laurenceb> http://www.nortonsalesinc.com/rocketry.php
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[13:05] <russss> I'm not sure what's happening on that web site, but it's cool.
[13:06] <MikeMc> yeah looks like fun
[13:06] <russss> http://nortonsalesinc.com/phpAlbum/main.php?cmd=album
[13:06] <MikeMc> hang on - the semi-naked ladies draped over the rocket parts or the space potatoes?
[13:06] <russss> the former
[13:07] <MikeMc> yeah that looks fun too - interesting way to sell rocket parts
[13:18] <gordonjcp> ah
[13:18] <gordonjcp> Norton <space> Sales
[13:18] <gordonjcp> not Norton's <space> Ales
[13:26] <MikeMc> lol
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[13:42] <MikeMc> Severe Weather warnings for this weekend
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[13:44] <russss> looks fin :/
[13:44] <russss> fun also.
[13:44] <russss> can I avoid going outside.
[13:44] <russss> I think the answer is yes
[13:48] <Jon_Apex> bahh its only a bit of rain :p
[13:55] <MikeMc> I was due to go camping this weekend in Sussex to do some astrophotography
[13:56] <MikeMc> Somehow I don't think i'll bother
[13:57] <SpeedEvil> oh no
[13:57] <SpeedEvil> Ah - guess not scotland
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[15:30] <jcoxon> afternoon all
[16:18] <Laurenceb> hi jcoxon
[16:18] <Laurenceb> how goes the tankage?
[16:20] <jcoxon> ummm haven't made any more progress really
[16:20] <jcoxon> have ordered a perastaltic pump to play with
[16:20] <jcoxon> and am about to make an order for some photodiodes
[16:20] <Randomskk> so it turns out the kitchen unit worktop, despite being metal, is an absolutely atrocious heatsink
[16:20] <Laurenceb> its stainless
[16:20] <Laurenceb> so not suprising
[16:20] <Randomskk> yup, you warned me
[16:21] <Randomskk> debating between a cpu heatsink and fan, or watercooling from the tap
[16:21] <Laurenceb> jcoxon: I'm not convinced by perastaltic pumps
[16:21] <Laurenceb> likely to break in bad ways at low temperature
[16:21] <jcoxon> hmmm that thought has crossed my mind
[16:22] <jcoxon> i'm not happy with these x-valves right now
[16:22] <jcoxon> they don't 'just' work
[16:23] <Laurenceb> they are rated for low temperature use
[16:24] <jcoxon> i know
[16:24] <Laurenceb> we shouldnt need to drop ballest really fast
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[16:24] <Laurenceb> how fast are you dropping ballast in tests?
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[16:24] <jcoxon> i'm just running the valve open
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[16:25] <jcoxon> its not the speed i worry about - its more that it sometimes seems to stop
[16:27] <jcoxon> Laurenceb, you don' t think it would be possible to actively heat the pump to stop it freezing up?
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[16:27] <Laurenceb> the pump is going to heat itself
[16:28] <Laurenceb> due to the coil resistance
[16:28] <jcoxon> so what are your fear then?
[16:28] <Laurenceb> well I was worried about a larger valve due to the power use
[16:28] <Laurenceb> and a pump due to it jamming
[16:29] <jcoxon> the tubing in the pump is rated down to -50
[16:29] <jcoxon> so thats okay
[16:29] <jcoxon> Laurenceb, i think its worth trying - better we find out now then later :-p
[16:30] <Laurenceb> ok I guess
[16:30] <Laurenceb> silicone rubber?
[16:30] <jcoxon> the one i order is silicone
[16:30] <jcoxon> but there are other types
[16:30] <Laurenceb> whats the diameter of the tube?
[16:31] <jcoxon> i've got up to 5mm for this
[16:31] <jcoxon> gives 82ml/min
[16:31] <jcoxon> http://www.williamson-shop.co.uk/200-series-peristaltic-pump---6v-dc-146-c.asp
[16:35] <Laurenceb> yeah that looks like the best one
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[16:36] <Laurenceb> that flow rate is fine, but I'd worry about the power consumption
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[16:36] <jcoxon> Laurenceb, so for ballasthalo 3 we've got a 500ml tank
[16:36] <Laurenceb> that shouldnt be a problem then
[16:37] <Laurenceb> hmm I guess its not going to draw more than about an amp
[16:37] <jcoxon> i was going to give it its own bank of batteries
[16:37] <Laurenceb> so for transatlantic you are only going to run it for 2 hours max
[16:37] <Laurenceb> so thats only about 40 grams of lipos
[16:37] <jcoxon> yeah
[16:38] <jcoxon> lets see how it goes - this is the whole point of hte ballasthalo flights
[16:38] <Laurenceb> ok yeah its not too bad
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[16:39] <jcoxon> Laurenceb, i'm nearly there with this payload :-p
[16:39] <Laurenceb> what are you using?
[16:40] <jcoxon> just need a few more temp sensors, photodiode and the pump
[16:40] <Laurenceb> how will you mount the photodiode?
[16:43] <jcoxon> still deciding - both yours and steve's ideas are good
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[16:43] <jcoxon> if i can find an nice 3 way junction i'll probably to yours
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[16:46] <Laurenceb> thers loads
[16:47] <Laurenceb> aquarium supplier, RS - even B&Q used to sell them
[16:48] <jcoxon> 5mm is a lot easier to find then 1.6mm
[16:49] <Laurenceb> ah
[16:49] <Laurenceb> you want 1.6mm ?
[16:49] <jcoxon> the valves are 1.6 while the pump is 5
[16:50] <Laurenceb> so you want a 1.6mm three way?
[16:50] <Laurenceb> do you have the pump?
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[16:51] <jcoxon> i don't have it yet
[16:51] <jcoxon> only ordered it yesterday
[16:53] <Laurenceb> do you have hose?
[16:53] <jcoxon> 1.6mm yes, i have 5mm on order
[16:54] <Laurenceb> where from?
[16:54] <jcoxon> the place i linked
[16:54] <jcoxon> pump + tubing + some barbed connectors
[16:55] <jcoxon> bbl
[16:56] <Laurenceb> http://www.williamson-shop.co.uk/micro416-connector-288-p.asp
[16:57] <Laurenceb> use that to go to larger diameter, then fit a three way. You need to get a large tube going up to use as the level sensing tube anyway
[16:58] <Laurenceb> bbl
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[17:04] <MikeMc> evening
[17:04] <Jon_Apex> hello
[17:05] Nick change: Jon_Apex -> JonApex
[17:05] Nick change: JonApex -> Jon_Apex
[17:05] <Randomskk> yo Jon_Apex
[17:05] <Randomskk> how goes your report
[17:05] <Jon_Apex> getting there. you?
[17:05] <Randomskk> it's all in latin so far
[17:05] <Randomskk> still
[17:06] <Jon_Apex> ha
[17:06] <Randomskk> will be going all out on it shortly
[17:07] <Randomskk> btw one of those peltiers was drawing 50W with no heatsink and that was after it had been on for a bit, so I suspect the internal resistance builds up - I can believe 100W or thereabouts when properly heatsinked
[17:07] <Jon_Apex> good good
[17:07] <SpeedEvil> Err - no
[17:07] <Randomskk> so long as it's just not just dumping all that into heat
[17:07] <SpeedEvil> That's not how they work
[17:07] <Randomskk> SpeedEvil: aww
[17:07] <SpeedEvil> It does
[17:07] <SpeedEvil> It all goes into heat
[17:07] <Randomskk> I mean, and not using any to also move heat from the other side.
[17:07] <Randomskk> obviously all the energy goes to heat eventually
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[17:07] <SpeedEvil> If you connect 50W to it, it pumps say 10W from the environment, and the hot side gets heated by 60W
[17:08] <Randomskk> they're rated at 100W but were cheap and from china so...
[17:08] <SpeedEvil> The whole thing rises rapidly in temperature until it desolders itself.
[17:08] <SpeedEvil> Or otherwise destroys itself.
[17:08] <Randomskk> hence the requirement for heatsinking
[17:08] <SpeedEvil> yes
[17:09] <SpeedEvil> Wander round digikey - there are some decent peltier datasheets - with graphs of cooling at various delta-t's and powers
[17:09] <Randomskk> but will it draw the full power the whole time it's operating, or will the current drop as it gets hotter?
[17:09] <russss> yeah I haven't found a use for my 400W peltiers yet.
[17:09] <SpeedEvil> these will give you an idea of the shape of hte graph
[17:09] <SpeedEvil> Randomskk: full power
[17:09] <russss> Randomskk: what's the model of it?
[17:09] <SpeedEvil> Randomskk: pretty much
[17:09] <Randomskk> SpeedEvil: so if it's drawing 50W when it's rated 100, something is wrong somewhere
[17:10] <Randomskk> russss: TEC1-12709
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[17:10] <SpeedEvil> http://www.cui.com/pdffiles/CP20151.pdf
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[17:10] <SpeedEvil> that's a reasonable datasheet
[17:11] <russss> not the same brand as mine I don't think
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[17:11] <russss> it seems like it only draws max current if delta t is 0 though?
[17:11] <SpeedEvil> There is a very weak dependance of voltage on temperature
[17:12] <SpeedEvil> If you're referring to the above datasheet - no
[17:12] <SpeedEvil> you need to carefully read the axes and understand what all the laabels mean
[17:12] <russss> aha. Mine are TEC1-12726
[17:12] <Randomskk> have you measured their actual power comsumption?
[17:13] <SpeedEvil> it's a graph of - on the top - input voltage for several currents at various delta-t along the x axis
[17:13] <Randomskk> I need to hook it up to a multimeter to actually check the current I guess
[17:13] <russss> I don't have a power supply big enough to hand, heh
[17:13] <russss> the bench PSUs at the hackspace only go up to 5A.
[17:13] <Randomskk> I'm using a 600W ATX computer PSU
[17:14] <Randomskk> it can do some 430W on 12V
[17:14] <SpeedEvil> and on the bottom it's heat pumped at various delta-ts and a selection of currents
[17:14] <Randomskk> £20
[17:15] <Randomskk> SpeedEvil: so at 0 delta-T it pumps something like 4W on 2A?
[17:15] <SpeedEvil> yes - for this one
[17:16] <Randomskk> so you want the smallest delta-T possible?
[17:16] <SpeedEvil> you can probably more or less scale that to any peltier
[17:16] <Randomskk> it seems like the heat pumped goes down as the delta-T goes up, for the same current/voltage
[17:16] <Randomskk> and the lines at the top are pretty much straight, e.g. it has some relatively consistent internal resistance, V=IR
[17:17] <Randomskk> so "apply 4V, 2A will flow, at dT=70 you get no heat pumped, going up linearly to dT=0 for 4W pumped
[17:20] <SpeedEvil> pretty much, yes
[17:20] <Randomskk> interesting. I measure approx 3ohms over it
[17:20] <Randomskk> at 12V that would give me 4A and 48W, which is also the power I measured on a wattmeter with it in operation
[17:21] <SpeedEvil> One interpretation is that the internal thermal resistance is 70C/8W = 8C/W or so
[17:21] <Randomskk> which would rather imply that these modules are actually 50W at 12V?
[17:21] <SpeedEvil> Dunno, possibly.
[17:21] <SpeedEvil> Inflating the specs would not surprise me.
[17:22] <Randomskk> hmm
[17:22] <Randomskk> the ebay page actually lists its resistance as 1.3 to 1.5 ohms
[17:22] <SpeedEvil> I would try connecting well heatsunk and insulating the cold side, and crank the voltage up slightly measuring temp until you hit 60C
[17:22] <SpeedEvil> 60C delta-T
[17:23] <Randomskk> yea. I need to rig up some temperature sensors and heatsinks and see what I can measure
[17:24] <Randomskk> so I guess the question is whether I've been sent the wrong thing, given the wrong stats or are measuring something wrong
[17:25] <Randomskk> or my dmm is a load of shit, I turn it off and on again and I'm getting 1.7 ohms
[17:25] <SpeedEvil> I make it you get 1/15000l of water frozen a second at 20W
[17:25] <SpeedEvil> -20W
[17:26] <Randomskk> is that just the enthalpy or a change in temperature too?
[17:26] <SpeedEvil> Or 240ml/hour
[17:26] <russss> I vote try it and see.
[17:26] <SpeedEvil> IIRC it's 300KJish
[17:26] <SpeedEvil> I was neglecting change in temp
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[17:26] <SpeedEvil> 200mlish then
[17:27] <Randomskk> 334kJ/kg enthalpy of fusion
[17:27] <Randomskk> 4kJ/kg/degree C s.h.c.
[17:28] <Randomskk> I guess a cold water heatsink would be the best I can do then
[17:28] <Randomskk> or maybe a jug of water left in the fridge, it'd be colder but soon warm up
[17:29] <Randomskk> still, 1L of fridge-temp water might be cold enough to get a decent power transfer from the water-to-be-frozen to freeze it before the water-heatsink gets too hot
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[17:34] <rjharrison> hey all
[17:34] <rjharrison> Any one heard from spudnick143
[17:34] <rjharrison> Any one heard from spudnick14
[17:34] <Randomskk> nope
[17:34] <rjharrison> Did they have success ?
[17:35] <Jon_Apex> no idea
[17:35] <Randomskk> they haven't reported in and nothing on their website
[17:35] <rjharrison> OOhh what's the site?
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[17:35] <Randomskk> http://www.spudnik1.co.uk/
[17:36] <Randomskk> http://absolute.myzen.co.uk/spudnik/view.php?N=uploads/P1010527.jpg what on earth
[17:38] <Randomskk> be sure to check out their The Founders page
[18:07] <Laurenceb> lmao
[18:08] <Laurenceb> needs shopped pedobear
[18:08] <Randomskk> hahaha
[18:08] <Randomskk> I wonder how they got on though
[18:08] <Randomskk> or if they're still sitting there waiting for a text message
[18:09] <Laurenceb> http://absolute.myzen.co.uk/spudnik/uploads/P1010534.jpg
[18:09] <Laurenceb> seriously what the hell?
[18:09] <russss> heh, yeah likely
[18:09] <Randomskk> how did that even win their competition
[18:09] <Randomskk> the one in a rocket is way better
[18:12] <Laurenceb> I was reading an interesting idea on nasaspceflight forums
[18:12] <Laurenceb> for n-prize vehicles, use a ground based air cannon to launch a ramjet
[18:13] <Laurenceb> this flies up reaching mach6 or more before burning out around 30Km, then fires a solid stage to reach orbit
[18:14] <Laurenceb> its probably a lot harder than a rockoon, but its interesting that you can launch ramjets with a pneumatic cannon
[18:15] <russss> railgun!
[18:15] <russss> :P
[18:15] <Randomskk> railgun would be a fun way to do it
[18:16] <Randomskk> you could even do it in a circular accelerator, like a massive cyclotron
[18:16] <Randomskk> takes stupid amounts of energy though
[18:16] <Randomskk> gigantic capacitor bank :P
[18:16] <Randomskk> I wonder if you could just hand-make one absolutely gigantic capacitor
[18:16] <russss> I'm fairly sure NASA were looking at a railgun launcher at one point
[18:16] <Laurenceb> too hard - I was looking at stuff that can be done cheaply
[18:17] <Laurenceb> http://home.earthlink.net/~altaccel/trimode/arla-int.htm
[18:17] <russss> yeah, you'd need some crazy massive capacitors
[18:18] <Laurenceb> http://home.earthlink.net/~altaccel/trimode/rj-bomar.htm thats interesting, its so simple
[18:18] <russss> "launch to space with an electromagnetic railgun" http://research.lifeboat.com/ieee.em.pdf
[18:20] <SpeedEvil> Laurenceb: plug ramjets are fun
[18:20] <SpeedEvil> Laurenceb: fuel+oxidiser in a tube, and you shoot the projectile through it
[18:20] <Laurenceb> way hard to make cheaply for a small sat
[18:21] <Laurenceb> and ramjets themselves are expensive and hard if you want mach5, even if you use an ablative nozzle (what that site suggests)
[18:21] <Laurenceb> you need to use stainless for the intake and the flame holder is hard
[18:22] <Laurenceb> its way way harder than rockoons
[18:23] <Laurenceb> but an gas cannon launched ramjet would be a fun project
[18:32] <sbasuita> Ramjet to Mach 7,
[18:32] <sbasuita> 90 Degree Angle,
[18:32] <sbasuita> 2,500 fps Rocket - LV Coast Altitude = 265 mi
[18:32] <sbasuita> is that realistic/
[18:34] <Laurenceb> yes, but hard
[18:34] <Laurenceb> there are better ways but its interesting
[18:43] <jcoxon> back
[18:46] <Laurenceb> jcoxon: use larger tube?
[18:54] <SpeedEvil> ramjets mean you're in draggy air longer
[19:00] <Laurenceb> it doesnt matter as you have decent thrust and high effective ISP
[19:02] <SpeedEvil> true
[19:07] <Laurenceb> but compared to rockoons, the last stage is roughly equivalent, the balloon+launcher is about as hard as a cannon, but then you have a ramjet as opposed to another rocket stage
[19:07] <Laurenceb> rockoon is a lot nicer
[19:11] <SpeedEvil> yeah
[19:11] <SpeedEvil> For small masses
[19:11] <SpeedEvil> once you get above a few kilos, it starts to get awkward
[19:11] <SpeedEvil> A balloon to hoist a ton isn't going to be real trivial
[19:13] <jcoxon> this might be interesting to apply for: http://www.bnsc.gov.uk/12029.aspx
[19:13] <SpeedEvil> Indeed
[19:17] <SpeedEvil> 5000 isn't insane for a ~n-prize class launch
[19:17] <SpeedEvil> It may be seen as too ambitious though
[19:20] <jcoxon> SpeedEvil, hehe i was thinking more for normal balloon activities
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[19:37] <jcoxon> hmmm do you think its a bad idea to put my callsign on a morse beacon for a balloon flight?
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[19:53] <rjharrison_> Hey guys they recovered the payload
[19:54] <rjharrison_> Cams failed
[19:54] <Laurenceb> http://hackaday.com/2009/11/11/single-wing-flight-based-on-maple-seed-aerodynamics/#more-18325
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[19:54] <jcoxon> rjharrison, the spudnik guys?
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[19:55] <jcoxon> wow
[19:55] <sbasuita> Both cameras... ouch
[19:55] <natrium42> url?
[19:55] <rjharrison_> I sent an email
[19:55] <jcoxon> where did if go?
[19:56] <jcoxon> it*
[19:56] <MikeMc> well at least they got the payload back - that's something i suppose
[19:56] <natrium42> rjharrison_, i didn't get any emails :(
[19:56] <rjharrison_> They didn't say
[19:57] <jcoxon> its always good to get a payload back - can fly again :-)
[19:58] <rjharrison_> Yep they said it was an emotional day
[19:58] <rjharrison_> Will foward email later having a meal
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[19:59] <jcoxon> wow a forecast from lunch time today from where they were, getting to 30km alt would have them landing just south of oxford
[20:06] <sbasuita> The monocopter is really cool
[20:09] <natrium42> jcoxon, somebody launched in the UK?
[20:09] <jcoxon> natrium42, yeah some guys down in devon launched
[20:09] <jcoxon> called spudnik1
[20:09] <natrium42> cool
[20:09] <natrium42> do they have a site?
[20:09] <jcoxon> www.spudnik1.co.uk
[20:09] <jcoxon> however there isn't much info
[20:10] <natrium42> haha @ potato
[20:11] <natrium42> good stuff
[20:11] <jcoxon> the weather is pretty rough so i'm really pleased that it was recovered
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[20:25] <jcoxon> natrium42, yay for google latitude
[20:32] <natrium42> :)
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[20:52] <SpeedEvil> Laurenceb: neat - I can't see any reason why it's better than a heli with two blades though.
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[21:53] <MikeMc> evening all
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[22:11] <Jon_Apex> evening
[22:12] <MikeMc> http://www.flickr.com/photos/nad/3972563876/
[22:12] <Jon_Apex> haha
[22:12] <Jon_Apex> very good