highaltitude.log.20090619

[00:17] <Laurenceb> SpeedEvil: http://handle.dtic.mil/100.2/ADA310680
[00:20] <SpeedEvil> diddn't you paste that before?
[00:21] <Laurenceb> maybe
[00:26] <Laurenceb> silica cloth phenolic silica power does best
[00:26] <Laurenceb> rather hard to make unfortunately, but nice low density
[00:27] <Laurenceb> some of the 3M silica cloths have crazy tensile strenght
[00:28] <Laurenceb> pages 23-28 are interesting
[00:30] <Laurenceb> asbestos does well :P
[00:36] <SpeedEvil> :)
[00:40] <SpeedEvil> however
[00:41] <SpeedEvil> silica cloth epoxy, silica powder is relatively simple
[00:41] <Laurenceb> magnesium oxide fibre / arcrylic is good
[00:42] <Laurenceb> but ver head to make and megnesium firbre seems to be hard to obtain
[00:43] <Laurenceb> char depth is important, as you want a thin nozzle to save weight
[00:43] <Laurenceb> as is density
[00:47] <SpeedEvil> sample 16
[00:47] <SpeedEvil> epoxy/silica cloth - nothing else
[00:48] <SpeedEvil> .04" radius increase after 30s
[00:48] <SpeedEvil> or 2.2mm dia or so
[00:50] <Laurenceb> not too bad
[00:52] <SpeedEvil> and you don't need to rely on it for strength - nothing stops you putting a carbon overwrap on it
[00:53] <Laurenceb> I guess
[00:53] <Laurenceb> 20 is good
[00:54] <SpeedEvil> 18 - silica powder/epoxy is confusing
[00:54] <SpeedEvil> the throat narrows!
[00:54] <Laurenceb> not sure if you can get nitrile additives for epoxy
[00:54] <SpeedEvil> very easy to make though
[00:55] <Laurenceb> I'm guessing the char region expands and pushes out the silica fibre
[00:56] <Laurenceb> I guess you could make a test nozzle to start with, slice it in half and measure the char depth, then make a "production" nozzle with varying thickness
[00:56] <SpeedEvil> no - silica powder
[00:57] <SpeedEvil> no fibre reinforcement at all
[00:57] <Laurenceb> ah
[00:59] <Laurenceb> its very heavy
[00:59] <SpeedEvil> ?
[00:59] <SpeedEvil> they diddn't control for the shape
[00:59] <SpeedEvil> so that doesn't mean much
[01:00] <SpeedEvil> they just machined the insides
[01:00] <Laurenceb> page 20?
[01:00] <Laurenceb> hmm surely they have roughly equivalent diameters
[01:01] <SpeedEvil> page 6
[01:02] <SpeedEvil> after _ablative_test_nozzles_
[01:03] <Laurenceb> ah ok
[01:03] <SpeedEvil> Also - if it has silica or silica cloth, and the remainder is resin, it doesn't matter how you makeup the silica - if something has the same resin fraction, the density will be the same
[01:04] <SpeedEvil> ah - beginning of page 9.
[01:04] <SpeedEvil> erosion begins at the start of the throat
[01:04] <SpeedEvil> and you get a film cooling effect
[01:04] <SpeedEvil> for a bit - hence the low initial loss rate
[01:04] <Laurenceb> ah yeah
[01:04] <SpeedEvil> implying you could possibly enhance that with a bulge of epoxy or something in the chamber
[01:05] <SpeedEvil> unreinforced, or lightly reinforced with nylon
[01:06] <SpeedEvil> nylon/phenolic is - expectedly - rather bad.
[01:06] <SpeedEvil> 64
[01:06] <Laurenceb> the thermal properties of the resin are very important if you want the wall temperature to be kept low
[01:06] <Laurenceb> which is important for minimising weight
[01:06] <SpeedEvil> yes - why phenolic is good.
[01:06] <Laurenceb> I was aiming for 5mm
[01:07] <Laurenceb> for a 30 to 40 second burn
[01:07] <SpeedEvil> 2mm of many things - as an ablation depth seems plausible
[01:07] <Laurenceb> != char depth
[01:07] <SpeedEvil> I was assuming a CF overwrap
[01:09] <Laurenceb> yeah, but when the char region reaches the CF its not going to stop
[01:10] <Laurenceb> silica phenolic would work
[01:10] <Laurenceb> its probably possible to obtain silica phenolic rods, then machine them and overwrap
[01:11] <SpeedEvil> ah yes
[01:12] <SpeedEvil> some don't seem to char
[01:12] <SpeedEvil> 26
[01:17] <Laurenceb> CF insulator ablative might help
[01:17] <SpeedEvil> I suppose the figure of merit is laargely not throat diameter after 30s
[01:17] <Laurenceb> yeah
[01:17] <SpeedEvil> it's throat diameter + char after 30s
[01:18] <Laurenceb> many of them are acceptable throat ablation wise
[01:18] <Laurenceb> figure 13
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[01:20] <SpeedEvil> 26 looks interesting
[01:20] Action: SpeedEvil wonders what Buna N is.
[01:20] <Laurenceb> nitrile
[01:20] <Laurenceb> you can get it in resin form I think
[01:21] <Laurenceb> not sure how to use it as an epoxy additive
[01:21] <SpeedEvil> ah
[01:21] <Laurenceb> but yeah you can improve things a lot be wteaking the thermal properties of the resin
[01:21] <Laurenceb> ideally you want a thermal wave moving through the wall
[01:21] <SpeedEvil> 26 is using zirconia fibres
[01:21] <SpeedEvil> which are I think a very poor conductor
[01:22] <Laurenceb> so the region beyond the char zone doesnt even start to heat up
[01:22] <Laurenceb> ideall low thermal conductivity, high heat capacity and strongly endothermic decomposition
[01:22] <Laurenceb> I'm guessing nitril helps with that
[01:22] <SpeedEvil> well - it's listed as no char after 30s
[01:25] <Laurenceb> 53 is pretty amazing
[01:28] <Laurenceb> propane-phelo-formaldehyde
[01:28] <Laurenceb> interesting
[01:28] <SpeedEvil> I skipped over that as I diddn't notice the first line was 100s
[01:29] <Laurenceb> http://en.wikipedia.org/wiki/Phenol_formaldehyde_resin
[01:29] <Laurenceb> basically a type of phenolic
[01:29] <SpeedEvil> Ah
[01:29] <SpeedEvil> I specifically looked at that one too
[01:30] <SpeedEvil> as I was interested in what pearlite did
[01:31] <Laurenceb> I wonder if you could have a spun stainless nozzle and chamber
[01:31] <Laurenceb> with ablative liner
[01:32] <SpeedEvil> doens't sound impossible
[01:32] <Laurenceb> I guess if the char region reaches the steel the liner loses its structural strenght
[01:32] <Laurenceb> and falls off
[01:32] <SpeedEvil> but - it's got to get hot over a moderaate area before you get a blowout
[01:32] <SpeedEvil> also something to think of
[01:32] <SpeedEvil> nylon/phenolic is going to be lighter than quartz/phenolic
[01:33] <SpeedEvil> so you can have more of it
[01:33] <Laurenceb> true, but its not vastly heavier
[01:33] <Laurenceb> well phenolic ~1 , epoxy ~1.2, quartz fibre ~2.6 grams/cc
[01:34] <SpeedEvil> as an example - it rather sucks too bad to be a candidate
[01:34] <SpeedEvil> I slightly wonder about kevlar though
[01:37] <Laurenceb> in order not to have crazy accel you need to run the third stage a lot longer
[01:37] <Laurenceb> which kind of screws things up
[01:38] Nick change: KingJ -> kingj
[01:39] <SpeedEvil> hmm
[01:40] <SpeedEvil> why care about accel? What's crazy?
[01:41] <Laurenceb> 1.5KN, 4Kg mass
[01:41] <Laurenceb> 37G
[01:43] <Laurenceb> maybe a bit less, but at least 30G
[01:44] <SpeedEvil> hmm
[01:45] <SpeedEvil> what's the wet mass?
[01:45] <Laurenceb> ~24Kg
[01:46] <SpeedEvil> 10G is probably not that unreasonable.
[01:46] <SpeedEvil> but that implies quite deep throttling
[01:48] <Laurenceb> in the sim I'm running atm theres a coast of 4 minutes after second stage burnout
[01:49] <Laurenceb> so the third stage could run for a minute or so
[01:49] <Laurenceb> or 4 even :P
[01:49] <SpeedEvil> what does extending the burn time a lot - say to 5 mins do?
[01:49] <SpeedEvil> and using a really teeny engine.
[01:50] <Laurenceb> that should work fine
[01:50] <Laurenceb> if the engine is buildable
[01:50] <SpeedEvil> Which presumably would be somewhat easier to do regneratively.
[01:50] <SpeedEvil> that'd be what - 150N or so?
[01:51] <Laurenceb> yeah
[01:51] <SpeedEvil> hmm
[01:52] <SpeedEvil> In some ways that's harder.
[01:52] <Laurenceb> yeah
[01:52] <SpeedEvil> How badly does going monoprop H2O2 hurt?
[01:52] <Laurenceb> quite a bit
[01:53] <Laurenceb> but maybe not if theres a 4th stage
[01:53] <SpeedEvil> for the final stage only
[01:53] <SpeedEvil> hmm
[01:53] <Laurenceb> so the 3rd stage is a "standard module"
[01:53] <SpeedEvil> (to make cooling easier)
[01:53] <Laurenceb> then it launches a 4th stage mass ~4Kg or so
[01:53] <Laurenceb> using H2)2 mono
[01:54] <Laurenceb> that would probably work better
[01:54] <Laurenceb> in fact best to increase it and have a 10Kg or more 4th stage
[01:54] <Laurenceb> with 3Kg satellite
[01:55] <SpeedEvil> I wonder about film cooling.
[01:55] <SpeedEvil> tricky though
[01:55] <Laurenceb> too hard
[01:55] <Laurenceb> its why armadillo are always faffing about
[01:55] <SpeedEvil> I do like the concept of hacking it in - with a very rapid ablator to generate a cool film.
[01:56] <SpeedEvil> before the throat
[01:56] <Laurenceb> hmm
[01:56] <Laurenceb> 4th stage could actually increase payload to orbit with only a modest increase in total mass
[01:57] <Laurenceb> in fact if you scaled everything down... you may be able to get total mass < 100Kg
[01:57] <SpeedEvil> balloon from 20km?
[01:57] <Laurenceb> exactly
[01:58] <Laurenceb> a 4th stage with monoprop makes getting into orbit a lot easier
[01:58] <Laurenceb> and solves the accel problem
[01:58] <Laurenceb> also solves the attitude control problem
[01:58] <SpeedEvil> pressure fed?
[01:58] <Laurenceb> yes
[01:58] <SpeedEvil> Or still using the pump
[01:58] <Laurenceb> no pumps at all
[01:59] <Laurenceb> they dont solve any problems
[01:59] <SpeedEvil> makes sense in this case
[01:59] <Laurenceb> 1000Psi tanks work out best
[01:59] <SpeedEvil> as you don't need the thrust
[01:59] <Laurenceb> to make tanks that are fairly strong you need a good fraction of the weight of a 1000psi tank
[02:00] <Laurenceb> add in the mass of a pump and its not worth it at this scale
[02:02] <natrium42> that's what she said
[02:02] <Laurenceb> oh dear
[02:05] <Laurenceb> so 7 modules and a 4th stage with pressurised H2O2 sphere and 5 motors
[02:05] <Laurenceb> one main and 4 attitude control motors
[02:12] <Laurenceb> actually nozzle 17 is promising
[02:12] <SpeedEvil> hmm
[02:13] <SpeedEvil> going to sleep - yes - if you're going the phenolic route
[02:13] <SpeedEvil> night
[02:13] <Laurenceb> cya
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[02:41] <edmoore> am drunk
[02:41] <edmoore> now for bed time
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[08:52] <Laurenceb> hello folks
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[10:48] <Laurenceb> http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA373361&Location=U2&doc=GetTRDoc.pdf
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[11:12] Nick change: kingj -> KingJ
[11:18] <Laurenceb> http://www.responsivespace.com/Papers/RS4%5CPapers%5CRS4_4004P_Tsohas.pdf
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[12:45] <mc-> Laurenceb, have you allowed for larger nozzles for the upper stages in your design?
[12:47] <SpeedEvil> you don't need them that badly
[12:47] <Laurenceb> hi
[12:48] <mc-> and also can run at lower pressure for the upper stages
[12:48] <SpeedEvil> what are those couple of PDFs?
[12:48] <Laurenceb> nope, they weigh too much and you launch at 20Km anyway
[12:48] <SpeedEvil> Laurenceb: optimal expansion means large nozzles
[12:48] <Laurenceb> first one is groovy UAV idea, 2nd is a hybrid launcxher design
[12:48] <mc-> have you seen Armadilloaerospace
[12:48] <Laurenceb> exactly
[12:48] <Laurenceb> mc_: sure, I check all the updates
[12:49] <Laurenceb> SpeedEvil: you cant get optimal
[12:49] <mc-> Armadillo were testing in an altitude chamber, and have a large nozzle
[12:49] <Laurenceb> have to comprimise at about 10 time or so
[12:49] <Laurenceb> yeah
[12:50] <Laurenceb> - 10 times expansion ratio
[12:50] <SpeedEvil> Of course you can't
[12:50] <SpeedEvil> you want to approach it as best you can.
[12:50] <SpeedEvil> Launch vehicle diameter is a comon compromise
[12:51] <Laurenceb> without a horrendously heavy nozzle
[12:51] <SpeedEvil> (best as you can till siminishing returns
[12:51] <Laurenceb> I was thinking about 100mm
[12:51] <Laurenceb> exit diameter
[12:51] <Laurenceb> ~30mm throat
[12:52] <SpeedEvil> What's the difference from 10:1 to 100:1 in ISP - about 5%?
[12:52] Action: SpeedEvil tries to remember the curves
[12:52] <Laurenceb> theres a simple equation... check wikipedia
[12:52] <SpeedEvil> meh
[12:53] <Laurenceb> http://en.wikipedia.org/wiki/Rocket_engine_nozzle
[12:53] <SpeedEvil> doing other stuff ATM, sorry - what're the PDFs earlier posted?
[12:53] <Laurenceb> second one is interesting - launch design
[12:54] <Laurenceb> oh I modified my sim code to use a 4th stage with peroxide monoprop
[12:54] <Laurenceb> its interesting, delta v is lower at ~8.8Km/s, but it can reach a 2000Km circular orbit instead of 600Km
[12:55] <Laurenceb> and it solves the crazy accel problem
[12:55] <SpeedEvil> 100n or so 4Kg?
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[12:55] <Laurenceb> no, really low
[12:55] <Laurenceb> <1N
[12:56] <SpeedEvil> hmm
[12:56] <Laurenceb> running for about an hour
[12:56] <SpeedEvil> I wonder what you'd make the nozzle from
[12:57] <Laurenceb> you can get thrusters thatd work off the shelf
[12:57] <SpeedEvil> Off the expensive shelf!
[12:57] <Laurenceb> they are spun stainless, ~100grams mass
[12:57] Action: SpeedEvil suspects.
[12:57] <SpeedEvil> ah
[12:57] <SpeedEvil> they work with the right concentration?
[12:57] <Laurenceb> yes
[12:57] <Laurenceb> ~90%
[12:58] <SpeedEvil> specced for the burn time
[12:58] <Laurenceb> then add some vanes for attitude control
[12:58] <Laurenceb> prob not continuously
[12:58] <Laurenceb> they are designed for pulsed use
[12:59] <Laurenceb> but that would probably work too
[13:00] <Laurenceb> use jet vanes and the entire thing is <200 grams
[13:00] <SpeedEvil> black people are just as dense as white people
[13:00] <SpeedEvil> oops
[13:00] <Laurenceb> lool
[13:01] Action: Laurenceb sticks them in a hybrid motor and measures the ISP to determine this
[13:02] <Laurenceb> that was my other idea, maybe a peroxide/polymer hybrid would be better
[13:02] <SpeedEvil> regression and ignition are surely hopeless for that burn itme?
[13:03] <Laurenceb> for the modules
[13:03] <Laurenceb> its perfect burn time wise
[13:04] <mc-> polymer as a fuel?
[13:04] <SpeedEvil> ah
[13:04] <Laurenceb> I think it may work out better, ISP is probably about equivalent, and you shrink the 1000PSI tank by 25% and the fuel moves to a 500PSI cylinder thats shorter due to the higher density (especially for acrylic)
[13:05] <SpeedEvil> and simplify the injector a bit
[13:05] <SpeedEvil> polymer, or wax?
[13:05] <Laurenceb> the injector is simpler and lighter by ~100 grams
[13:05] <Laurenceb> acrylic
[13:05] <SpeedEvil> lsusb
[13:05] <SpeedEvil> meh
[13:05] <mc-> isnt HTPDE better as a fuel?
[13:06] <SpeedEvil> not really in many ways
[13:06] <SpeedEvil> wax turns out to actually be really good
[13:06] <SpeedEvil> it degenerates into essentially parrafin once it melts
[13:06] <Laurenceb> you save about 100 grams on the injector and 100 grams or more on the tank
[13:06] <Laurenceb> yeah but its light and the regression rate is too high
[13:07] Action: SpeedEvil ponders phenolic/nylon as fuel/chamber/throat
[13:07] <Laurenceb> oh and you save helium weight and cost
[13:07] <Laurenceb> heh - youd need some good sim code to see if you could maintain the nozzle shape
[13:07] <mc-> can H202 and nitrous mix?
[13:08] <mc-> then you can self pressurize the H2O2
[13:08] <Laurenceb> dunno, but nitrous is a pain to handle
[13:08] <Laurenceb> as peroxide looks to be obtainable, its much nicer
[13:08] <Laurenceb> just pour it in (wearing protective clothing of course)
[13:09] <mc-> nitrous should be easy to handle, all the current hybrids use it
[13:09] <Laurenceb> this thing would be about 3 orders of magnitude larger
[13:09] <Laurenceb> make that 4
[13:09] <mc-> spaceship 1 uses nitrous
[13:09] <Laurenceb> also the ISP is lower with nitrous
[13:10] <Laurenceb> your only advantage is its self pressurising, but thats a pain to control
[13:10] <SpeedEvil> for a long flight, you would have some solar gain
[13:11] <Laurenceb> 40S != long
[13:11] <mc-> H202 for high ISP, + a little nitrous for self-pressurization
[13:12] <SpeedEvil> Ah - I was assu,ming you meant as a replacement for the 4th
[13:12] <mc-> put in some heat into the nitrous so it maintains a constant pressure.
[13:13] <Laurenceb> hmm actually its almost as good
[13:13] <Laurenceb> and has the advantage that the O/F curve is smoother
[13:13] <Laurenceb> making use in a hybrid closer to the theoretical
[13:14] <SpeedEvil> mc-: that ends up being annoying
[13:14] <SpeedEvil> mc-: the amount of heat you need can be quite high
[13:15] <mc-> agreed, the nitrous needs to be in a jacket around the chamber to get the heat into it.
[13:15] <Laurenceb> you can pressurise nitous with helium
[13:15] <Laurenceb> helium isnt soluble in the liquid nitrous
[13:15] <Laurenceb> guess you could design something that allows both options
[13:16] <mc-> are you saying above nitrous is similar ISP to H202?
[13:16] <Laurenceb> yeah
[13:16] <mc-> interesting
[13:17] <mc-> wonder why the Brits chose H202 for Bluestreak?
[13:17] <Laurenceb> both about 330 theoretical
[13:17] <Laurenceb> australia is hot
[13:17] <Laurenceb> nitrous pressure is crazy
[13:17] <mc-> could be
[13:17] <Laurenceb> Bluestreak had low tank pressure
[13:19] <mc-> so you would have to fill the tank in a cold climate, so it didn't overpressure.
[13:19] <Laurenceb> hmm I see
[13:20] <Laurenceb> nitrous density is lower and O/F ratio is higher
[13:20] <mc-> so you would need a larger tank, but offset that against no need for He pressurization
[13:20] <Laurenceb> ends up need ing 20% more tank volume
[13:21] <Laurenceb> nope
[13:21] <Laurenceb> you need He pressurisatiopn to make it work reliably
[13:23] <mc-> I think a control system would be able to maintain fairly constant nitrous pressure
[13:23] <Laurenceb> ewww
[13:23] <Laurenceb> its a horribleness you dont need
[13:24] <mc-> you're probably right, a small tank with He isn't too hard, a high pressure regulator is needed
[13:25] <Laurenceb> nope
[13:25] <Laurenceb> it works out better having a larger tank with helium ullage
[13:26] <Laurenceb> optimal is double the tank size
[13:26] <Laurenceb> - 50% full tank at ignition
[13:26] <mc-> what pressure?
[13:27] <Laurenceb> 1000PSI
[13:27] <mc-> that's the nitrous selfpressure
[13:27] <Laurenceb> nope
[13:27] <Laurenceb> nitrous selfpressure is undefined
[13:28] <Laurenceb> probably a lot less at 20Km
[13:28] <mc-> it's around 1000PSI at 20C, but would drop fast as the temperature drops
[13:28] <Laurenceb> yes
[13:28] <Laurenceb> http://www27.wolframalpha.com/input/?i=nitrous+oxide
[13:30] <mc-> I like the idea, so you fill up the ullage with He, and it holds the pressure more stable
[13:31] <Laurenceb> yeah
[13:31] <Laurenceb> however... a high pressure He cylinder allows for something groovy
[13:31] <Laurenceb> have the tank at 0psi
[13:32] <Laurenceb> thwen pressurise when you want to fire it
[13:32] <Laurenceb> hmm but its be rather unpredictable
[13:32] <mc-> what's the advantage of that?
[13:34] <Laurenceb> it saves some weight actually...
[13:34] <Laurenceb> also avoids the need for a valve in the injector
[13:34] <Laurenceb> just a blow off cap
[13:35] <Laurenceb> or a pyro blow off cap
[13:36] <mc-> you can open a spool valve on the oxidizer tank at ignition
[13:37] <Laurenceb> yeah
[13:38] <mc-> or have a piece of plastic as a valve which you burn away at ignition
[13:38] <Laurenceb> I've seen that done
[13:38] <Laurenceb> attitude control is a bit tricky
[13:39] <mc-> I was discussing this with SpeedEvil a few days ago.
[13:39] <mc-> Put the nozzle at CofG, and attitude control thrusters on a long lever arm
[13:40] <Laurenceb> long arm ?!
[13:40] <mc-> then the thrusters can be very small, as they are far away from the CofG
[13:40] <Laurenceb> or you could put them on the nose
[13:40] <mc-> yes
[13:40] <Laurenceb> just maybe
[13:41] <Laurenceb> a _slightly_ better plan
[13:41] <Laurenceb> however you can do nozzle injection
[13:41] <Laurenceb> which is move efficient and a lot lighter
[13:41] <Laurenceb> however you have to run stainless pipes down past the fuel
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[13:41] <Laurenceb> which is heavy
[13:42] <mc-> a thruster can be very small and light, if the main engine nozzle is at CoG
[13:42] <Laurenceb> - pointing through teh C of G
[13:43] <Laurenceb> not actually at it
[13:43] <Laurenceb> and ablative nozzles aret very accurate
[13:43] <Laurenceb> you need a few degrees of main nozzle deviation angle equivalent
[13:43] <Laurenceb> which makes nozzles heavy
[13:44] <mc-> with the nozzle at CoG, any thrust inaccuracies make the rocket crab a little, but don't affect attitude
[13:45] <mc-> your comment: - pointing through teh C of G - I mean nozzle at the CoG
[13:46] <Laurenceb> oh ok
[13:46] <Laurenceb> yeah but thats rather impossible
[13:46] <mc-> keeping the nozzle at CoG is possible with 2 tanks etc
[13:47] <Laurenceb> yeah, but with spherical tanks
[13:47] <Laurenceb> which are hard to optian
[13:47] <Laurenceb> *obtain
[13:47] <mc-> cylinder tanks, it would need 3 tanks total, 2 cylinders below CoG and 1 cylinder above CoG
[13:48] <Laurenceb> as the fuel is used its going to shift
[13:49] <Laurenceb> I dont think its worth the hassle to avoid a bit of extra attitude control thruster requirement
[13:49] <Laurenceb> as theres loads of other things like slosh and machining inaccuracy
[13:49] <Laurenceb> combustion instability
[13:49] <Laurenceb> lots of reasons its good to have lots of extra attitude control
[13:50] <mc-> agreed, slosh and other inaccuracies are in any design, so the thruster would need to overcome those.
[13:51] <mc-> I think the spaceship 1 thrusters were at the end of the wings, some distance from the CofG
[13:58] <Laurenceb> I think that nozzle injection is the way to go
[13:58] <Laurenceb> its about 50% better than nozzles ISP wise
[13:58] <Laurenceb> due to the way it interacts with the main flow
[14:00] <Laurenceb> http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19910000800_1991000800.pdf
[14:01] <mc-> nozzle injection is a full time job for a team of people
[14:02] <Laurenceb> solenoid + a pipe
[14:03] <Laurenceb> one of the aesiest ways to do it
[14:04] <mc-> you make it sound easy, but no amateur has ever built one
[14:04] <Laurenceb> theres enough test data to do the design and build the hardware
[14:04] <Laurenceb> then run a test to characterise it exactly
[14:04] <Laurenceb> and write the control loops
[14:05] <SpeedEvil> a test in vacuum
[14:05] <Laurenceb> you shouldnt have to come out with a second hardware revision
[14:05] <Laurenceb> shouldnt be that significant
[14:06] <Laurenceb> - depends on injection point and chamber pressure
[14:06] <mc-> 1 s/w eng + h/w eng + 1 mech eng + 1 sys architect = a team
[14:06] <Laurenceb> yep
[14:07] <Laurenceb> also need a boat and a barge
[14:07] <Laurenceb> - as in sea going barge
[14:07] <SpeedEvil> why
[14:08] <Laurenceb> boat = missin control, barge = launch/prep area
[14:08] <Laurenceb> with some shipping containers onboard for storage of propellants
[14:09] <Laurenceb> then you sail to the equator somewhere and launch the hab
[14:09] <SpeedEvil> so the equator is the reason?
[14:09] <Laurenceb> and doing it safely
[14:09] <Laurenceb> and reulations
[14:09] <SpeedEvil> you are required to get a launch permit from the UK wherever you launch
[14:09] <SpeedEvil> if you're a british citezen
[14:10] <Laurenceb> yeah, but you cant drop rocket stages over the UK
[14:10] <SpeedEvil> true
[14:10] <Laurenceb> its bad enough with HABs
[14:10] <SpeedEvil> without leet skillz.
[14:10] <mc-> it would need to be a non-british project, run by someone in a different country
[14:11] <Laurenceb> or just a HAB launch
[14:11] <Laurenceb> that lands somewhat lighter
[14:11] <Laurenceb> for soem unknown reason
[14:11] <SpeedEvil> mc-: As I read the law - you can't even take part in that sort of launch, and be legal
[14:12] <SpeedEvil> If it's not authorised under the auspices of another government
[14:13] <mc-> hmm, so the hardware could be built and tested in the UK, but the launch has to be done done elsewhere, without any UK involvement
[14:13] <SpeedEvil> Well...
[14:13] <SpeedEvil> There are various missile technology export questions that are then raised.
[14:14] <SpeedEvil> That's if you want to keep within the law
[14:15] <mc-> true. maybe if the design is published and open source, then a group elsewhere can build it
[14:15] <Laurenceb> to be serious youd want to do this 100% legally
[14:15] <Laurenceb> as the aim would be to launch cubesats for universities
[14:16] <SpeedEvil> Yeah
[14:16] <Laurenceb> I'm sure it wouldnt be impossible if you could demonstrate it was a serious and well intentioned effort
[14:17] <SpeedEvil> I'm not.
[14:17] <mc-> IMO, the legalities make the project too difficult.
[14:17] <SpeedEvil> I think getting a university involved is a requirement.
[14:17] <SpeedEvil> For several reasons.
[14:17] <mc-> getting to 100km first would be feasible
[14:17] <SpeedEvil> They're exempt from the 6K application fee.
[14:17] <Laurenceb> application for what?
[14:18] <SpeedEvil> for a launch.
[14:18] <Laurenceb> define launch
[14:18] <SpeedEvil> Orbital
[14:18] <Laurenceb> ok
[14:18] <mc-> I thought an application is needed to fly >100km
[14:18] <SpeedEvil> I think it actually may say something woolier
[14:18] <SpeedEvil> including suborbital
[14:18] <SpeedEvil> but I last read it a couple of years ago.
[14:18] <SpeedEvil> The outer space act
[14:19] <Laurenceb> heh £6K would cover the cost of this design
[14:19] <SpeedEvil> yeah
[14:19] <Laurenceb> excluding launch system
[14:19] <Laurenceb> - boat ect
[14:19] <SpeedEvil> Alternative - borat launch.
[14:19] <mc-> 6k is not a lot really, if the ppl working on the project are paid anything.
[14:19] <SpeedEvil> Green mankini - stretched a _lot_
[14:20] <Laurenceb> £6K is a lot less than a typical cubesat
[14:20] <SpeedEvil> 6K is probably possible - it's in the range I was looking at.
[14:20] <SpeedEvil> ut.
[14:20] <SpeedEvil> But
[14:20] <SpeedEvil> This is assuming you can do it _all_ on your own.
[14:21] <SpeedEvil> And buy essentially nothing expensive.
[14:21] <Laurenceb> £20K or more is a perfectly reasonable amount to spend
[14:21] <SpeedEvil> And pretty much have the required machines.
[14:21] <Laurenceb> there isnt anything expensive to buy
[14:21] <Laurenceb> thats the entire point of the design
[14:22] <SpeedEvil> You're easily going to burn a K or so on motor tests for fuel and parts alone - as you need to develop a couple of engines. Neglecting test stand costs
[14:22] <SpeedEvil> (field, rental of field, shed, tank farm, ...)
[14:23] <SpeedEvil> And I don't like to think what your insurance costs will be.
[14:24] <Laurenceb> or... my garden
[14:24] <SpeedEvil> I considered that.
[14:24] <SpeedEvil> One thing about rocket engines - pretty much unavoidably.
[14:24] <SpeedEvil> They're loud.
[14:24] <Laurenceb> or a local farmer
[14:25] <SpeedEvil> If you can find one willing to take the risk of your estate suing.
[14:26] <Laurenceb> or maybe you happen to know them and they dont care as long as you dont make a mess
[14:27] Action: SpeedEvil wonders what teh noise emission of a 1.5KN rocket are.
[14:27] <SpeedEvil> @100m
[14:27] <Laurenceb> probably not much compared to some of the quarries
[14:27] <Laurenceb> they do blasting at 1am sometimes
[14:29] <mc-> I was just reading that Armadillo were testing a self-pressurized LOX engine - so they must have worked out how to heat the LOX
[14:29] <SpeedEvil> And remember.
[14:29] <SpeedEvil> You are testing this thing for the purpose of killing weeds.
[14:29] <SpeedEvil> Stubborn weeds, like triffids.
[14:29] <Laurenceb> heh
[14:30] <Laurenceb> I's say attitude control and comms are pretty tricvky
[14:30] <SpeedEvil> comms - in a way isn't.
[14:30] <Laurenceb> yeah
[14:30] <SpeedEvil> As you're not going to be remote controlling it.
[14:30] <Laurenceb> pretty much off the shelf, especially at 868M<Hz
[14:30] <SpeedEvil> but for dev
[14:31] <Laurenceb> attitude has to be really good
[14:31] <Laurenceb> some of these sims I've run cant handle 0.1degree pointing errors
[14:31] <Laurenceb> you really need a fused gps/imu
[14:31] <SpeedEvil> What happens?
[14:31] <SpeedEvil> and is that persistant pointing error?
[14:32] <Laurenceb> goes into a highly elliptical or re-enters after half an orbit or so
[14:32] <Laurenceb> yes
[14:32] <Laurenceb> persistent
[14:32] <SpeedEvil> because if you've got a trajectory locked in, and are going closed-loop
[14:32] <Laurenceb> yes
[14:32] <SpeedEvil> on GPS
[14:32] <Laurenceb> thats my point
[14:32] <Laurenceb> you really want locked in trajectyory
[14:33] <Laurenceb> but all the tricky stuff has already been done - with hallams help :P
[14:33] <SpeedEvil> has he gotten it working?
[14:33] <Laurenceb> nope
[14:33] <SpeedEvil> the gps/blackfin
[14:33] <Laurenceb> he got tracking to work
[14:33] <SpeedEvil> on the lackfin?
[14:33] <Laurenceb> and I got position fixes working properly using kai borres code
[14:34] <SpeedEvil> so 'just' fixes?
[14:34] <SpeedEvil> got teh psuedoranges?
[14:34] <Laurenceb> I think so, but with raw data in a header
[14:34] <Laurenceb> the SE4120 wasnt rigged up
[14:34] <SpeedEvil> sounds sane anyway
[14:34] <Laurenceb> I think SE4120 + analogue devices IMU
[14:34] <Laurenceb> then a blackfin or maybe an arm
[14:35] <SpeedEvil> I think the IMU has too low a max G
[14:35] <Laurenceb> I've seen software tracking done on arm at 60MHz
[14:35] <Laurenceb> yeah
[14:35] <SpeedEvil> also - you're long enough that an ant on each end would be a plus
[14:35] <Laurenceb> certainly, but its a bit of a pain
[14:35] <SpeedEvil> true
[14:36] <Laurenceb> still theres a guy here writing a thesis on it
[14:36] <Laurenceb> its all to do with searching through the multiple possible solutions, looking for the one that agrees with the IMU
[14:37] <Laurenceb> as you have a +-n wavelenght ambiguity
[14:37] <SpeedEvil> well - ...
[14:37] <SpeedEvil> I would be looking at rather simpler
[14:37] <SpeedEvil> simply taking one as a 'master' - and computing the best fit delta to teh slave
[14:38] <Laurenceb> hes got it working with 4 antennas
[14:38] <SpeedEvil> nice
[14:38] <Laurenceb> but with the zarlink GP2102 correlator
[14:39] <Laurenceb> its mounted on a tripod with antennas on a sheet of kingspan
[14:39] <Laurenceb> ~40cm apart
[14:39] <Laurenceb> GP2102 and a really old ARM board
[14:40] <Laurenceb> I believe there is code for the GP2102 and transputer
[14:41] <SpeedEvil> fun. AFK for a bit.
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[14:58] <Laurenceb> so... technically a HAB mounted LGG needs a license
[15:07] <SpeedEvil> As I understand it, anything.
[15:07] <SpeedEvil> There isn't a mass limit
[15:07] <SpeedEvil> There are even procedures covering what they need to do to get a warrant to kick the doors of your control centre in
[15:08] Action: SpeedEvil has been weeding
[15:16] <Laurenceb> with a rocket engine?
[15:16] <Laurenceb> :P
[15:17] <SpeedEvil> no :)
[15:17] <SpeedEvil> Leather gloves.
[15:17] <Laurenceb> hmm theoretically using a high pressure tank and a regulator lets you get down to 50% the tank mass of He filled ullage
[15:17] <SpeedEvil> Hmm
[15:18] <Laurenceb> and a sensible polymer hybrid with approx 60% volume used by fuel is as good as kerosene
[15:18] <Laurenceb> duwe to the high density
[15:18] <SpeedEvil> how bad is drag initially?
[15:18] <Laurenceb> getting a He cylinder is tricky however
[15:18] <Laurenceb> not sure
[15:19] <Laurenceb> Im ignoring it
[15:19] <SpeedEvil> And are you implicitly assuming there that you will go highly supersonic
[15:19] <SpeedEvil> ah
[15:19] <SpeedEvil> it's better as there is less enclosed chamber volume
[15:19] <Laurenceb> it looks to be too bad to do ground, dut I didnt have 3D sim code working then
[15:19] <SpeedEvil> not as it reduces the frontal area
[15:19] <SpeedEvil> enclosing cvha,mber
[15:19] <Laurenceb> - without the sim code I would have assumed the 4th stage made it worse
[15:20] <Laurenceb> actually its the reverse
[15:20] <Laurenceb> http://www.mhoxygen.com/index.phtml?nav_id=28&product_id=298
[15:21] <Laurenceb> they are about 3 times heavier than they need to be :-/
[15:22] <Laurenceb> ideally you want a high pressure He cylinder then a 1.5 meter long 12cm diameter CF tube
[15:23] <Laurenceb> aluminum spheres would be better than those cylinders
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[15:26] <SpeedEvil> I assume you can't usefully overpressure He?
[15:26] <Laurenceb> overpressure?
[15:27] <SpeedEvil> I mean
[15:27] <SpeedEvil> do they hold 3*more at 9000PSI, than 3000PSI - or whatever their test is
[15:27] <Laurenceb> yes, but you dont want it to blow up
[15:27] <SpeedEvil> rated pressure
[15:27] <Laurenceb> you can go 50% over
[15:28] <SpeedEvil> I meaan - approach teh 'proof' test pressure
[15:28] <Laurenceb> but its still stupibly heavy
[15:28] <Laurenceb> like my spelling
[15:28] <Laurenceb> also <900grams isnt avaliable
[15:29] <SpeedEvil> Are little O2 cyls availbal?
[15:29] <SpeedEvil> I imagine tehy are made in bulk for the respirator industry
[15:30] <Laurenceb> you really want composite
[15:30] <Laurenceb> but aluminium would probably do
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[15:31] edmoore (n=ed@pomegranate.chu.cam.ac.uk) joined #highaltitude.
[15:31] <jcoxon> hey edmoore
[15:31] <Laurenceb> alu tensile strenght/weight is 5.5 times lower than standard grade CF
[15:31] <edmoore> yo
[15:31] <Laurenceb> hi jcoxon + edmoore
[15:32] <Laurenceb> some of the better stuff is 10 times
[15:32] <jcoxon> hows mayweek?
[15:39] <edmoore> very good
[15:39] <edmoore> did trinity and queens
[15:39] <edmoore> had june feast last night
[15:39] <edmoore> sat opposite David Mackay or the first half, which was awesome
[15:39] <edmoore> then after the intermission was sat next to the Master, so lots of teddies in space chat
[15:42] <Laurenceb> mayweek?
[15:42] Action: Laurenceb hasnt come across this tradition
[15:43] <jcoxon> oooo that sounds amazing
[15:43] Action: jcoxon misses mayweek a little
[15:44] <Laurenceb> obviously a cambridge thing :P
[15:44] <jcoxon> Laurenceb, mayballs and such
[15:44] <Laurenceb> oh ok
[15:45] Action: Laurenceb remembers the ball last year
[15:45] <Laurenceb> well vaguely
[15:45] <Laurenceb> I was very drunk
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[15:47] <jcoxon> Laurenceb, when are you going to build this rocket?
[15:51] <Laurenceb> when I have a design that works
[15:51] <Laurenceb> :D
[15:52] <Laurenceb> and before I get put in guantanamo
[15:52] <Laurenceb> hence leaving little room for construction time
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[16:13] <Laurenceb> SpeedEvil: http://www.google.co.uk/patents?id=TnYwAAAAEBAJ&pg=PA2&dq=nozzleless+hybrid+motor&source=gbs_selected_pages&cad=0_1
[16:14] <SpeedEvil> Laurenceb: Are you independantly wealthy?
[16:14] <SpeedEvil> :)
[16:14] <Laurenceb> maybe
[16:14] Action: SpeedEvil stabs most ptents.
[16:14] <Laurenceb> heh
[16:14] Action: Laurenceb just uses them as a source of ideas to pinch
[16:15] <SpeedEvil> Many of them are invalid on the face of it as being trivially obvious.
[16:15] <Laurenceb> I like the idea of spring loaded propellant
[16:15] <Laurenceb> independantly wealthy?
[16:15] <SpeedEvil> I have a sketch of a pistonless pump on a bit of A4, that together with a dated usenet post is prior art for a patent on pistonless pumps.
[16:15] <SpeedEvil> Laurenceb: As in can easily fund 10K or so of rocket.
[16:15] <Laurenceb> heh
[16:16] <Laurenceb> me too
[16:16] <Laurenceb> maybe 50K if I really tried
[16:16] <SpeedEvil> You were active on usenet?
[16:16] <Laurenceb> nope
[16:16] <SpeedEvil> ah
[16:16] <Laurenceb> is it even active these days?
[16:17] <SpeedEvil> ATM I'd have trouble coming up with 3K - unless I sold my house - which I'm not especially willing to do.
[16:17] <Laurenceb> money isnt an issue if you get it funded
[16:17] <SpeedEvil> No.
[16:18] <SpeedEvil> However, getting to the point where you can attract funding isn't free
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[16:18] <Laurenceb> come up with enough powerpoint and it is
[16:19] <Laurenceb> powerpoint is more important than something thats actually workable
[16:19] <SpeedEvil> Yeah.
[16:19] <Laurenceb> unfortunatly
[16:19] <SpeedEvil> Venture capitalists of various forms are a bit scarecer than they weree.
[16:19] <Laurenceb> theres lots of other sources
[16:20] <Laurenceb> BNSC gives money to some wacky projects
[16:20] <SpeedEvil> I mean all forrms.
[16:20] <SpeedEvil> including NGOs, and ...
[16:20] <Laurenceb> and even more to stuff that is so ill defined even the preople involved lose track of what there supposed to be doing
[16:20] <Laurenceb> e.g. POISE
[16:21] <Laurenceb> IIRC they've put about £20K into that
[16:21] <SpeedEvil> http://www.poise.com/
[16:21] <SpeedEvil> I guess not that.
[16:22] <Laurenceb> http://www.engineeringbritain.com/prgallery/space_experiment/06_G?full=1
[16:23] <Laurenceb> also a photographic definition of dorks for wikipedia to use
[16:23] <SpeedEvil> What a hideously designed website.
[16:23] <SpeedEvil> I can see 1/25th of the page at a time
[16:24] <SpeedEvil> Does it have anything other than pictures/
[16:24] <Laurenceb> IIRC thats the korean astronaut who nearly got fried when the soyuz went screwing during re-entry
[16:24] <jcoxon> Laurenceb, whats their space experiment then?
[16:25] <Laurenceb> http://www.engineeringbritain.com/space/archives/182-Space-experiment-competition-stars-announced.html
[16:25] <Laurenceb> jcoxon: knownes sure
[16:25] <Laurenceb> arg spelling
[16:26] <jcoxon> hehe
[16:26] <jcoxon> "ionospheric scintillation experiment"
[16:26] <jcoxon> interesting
[16:26] <jcoxon> not sure what that mean
[16:26] <jcoxon> s
[16:27] <Laurenceb> there was a lot of powerpoint and the conclusion was reached that schoolkids arent qualified to rewrite the firmware
[16:27] <Laurenceb> and that was the end of that one
[16:27] <jcoxon> oh right
[16:27] <Laurenceb> or not of course
[16:27] <Laurenceb> theres plenty of powerpoint to come, but little actual work
[16:28] <jcoxon> hmmmm, i was never sure of the whole thing really
[16:28] <jcoxon> by the time something has been put together they would have left school etc
[16:28] <Laurenceb> its basically looking at how the ionosphere effects gps signals
[16:28] <Laurenceb> jcoxon: yes, it was a silly idea to start with
[16:28] <SpeedEvil> rewrite teh firmware of a GPS?
[16:28] <Laurenceb> yes
[16:29] <Laurenceb> thats where it got even more silly
[16:29] <SpeedEvil> rewrite teh firmware - you might find some
[16:29] <SpeedEvil> Understand the GPS maths, and be able to rewrite teh firmware - probably not.
[16:32] <Laurenceb> http://www.westwardplastics.co.uk/d_selector.php?cat=Rod&subcat1=Extruded%&subcat2=%
[16:32] <Laurenceb> ^ expensive
[16:33] <SpeedEvil> ebay has some cheap acrylic rods
[16:36] <Laurenceb> yeah, £1500 for the fuel isnt actually that much
[16:37] <SpeedEvil> what's the total GLOW? Fuel is what - a eight of that?
[16:38] <Laurenceb> 160Kg approx
[16:38] <Laurenceb> yeah
[16:38] <Laurenceb> about 1/9 with polymer
[16:38] <SpeedEvil> you need it in long cylinders I assume?
[16:38] <Laurenceb> yes, not that long
[16:39] <Laurenceb> with 500psi tank and high pressure He tank, you can go for larger diameter
[16:39] <SpeedEvil> I thought they were 3m or so
[16:39] <Laurenceb> maybe 150mm
[16:39] <SpeedEvil> ah
[16:40] <Laurenceb> only a meter or so long
[16:40] <SpeedEvil> I do have some old 6" PVC drainpipe you could have for fuel.
[16:40] <Laurenceb> it has to be rather thicker
[16:40] <Laurenceb> as in 50mm thick
[16:43] <Laurenceb> hmm probably best to go with ~110mm diameter then 1.5m long tubes
[16:44] <Laurenceb> about 2m total lenght
[16:53] <Laurenceb> http://www.luxfercylinders.com/products/paintball/productspecifications/datasheet.pdf
[16:53] <Laurenceb> the full wrap composite is almost sensible
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[16:57] <Laurenceb> cya
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[17:05] Nick change: Fighter|sleep -> Fighter1405
[17:05] <Fighter1405> NTX2 is here :D
[17:09] <jcoxon> cool
[17:12] <Fighter1405> pins 1&3 are left floating yes?
[17:13] <jcoxon> they are RF ground
[17:14] <jcoxon> so you'll want to attach them to the ground part of the antenna
[17:14] <Fighter1405> And for just using a wire as an antenna?
[17:14] AlexBreton (n=Alexande@client-86-25-181-65.bkl-bng-012.adsl.virginmedia.net) joined #highaltitude.
[17:14] <AlexBreton> yo guys
[17:14] <AlexBreton> sbasuita, got the CF card
[17:15] <AlexBreton> 4GB
[17:15] <jcoxon> Fighter1405, for now yes
[17:16] <AlexBreton> 30MB/s read/write speed
[17:16] <Fighter1405> thanks jcoxon
[17:30] DanielRichman (n=DanielRi@78.146.177.110) joined #highaltitude.
[17:30] <AlexBreton> DanielRichman, got the CF card
[17:30] <DanielRichman> AlexBreton, good.
[17:30] <AlexBreton> we can do a full test soon
[17:30] <DanielRichman> AlexBreton, was road testing the gps + phone
[17:30] <DanielRichman> on the bus ;)
[17:30] <AlexBreton> endurance, amount of photos taken
[17:30] <DanielRichman> sent myself a text
[17:31] <DanielRichman> Sent me the following text
[17:32] <DanielRichman> (PM).
[17:33] Nick change: Fighter1405 -> Fighter|brb
[17:34] Laurenceb (n=laurence@dyres221-74.surrey.ac.uk) joined #highaltitude.
[17:35] <Laurenceb> back
[17:50] <sbasuita> AlexBreton, install hydrogen and make some beats
[17:50] <AlexBreton> hydrogen?
[17:50] <AlexBreton> why would I need that?
[17:50] <sbasuita> AlexBreton, for making beats
[17:50] <AlexBreton> got garageband
[17:50] <sbasuita> i bet garageband doesn't have a drum machine
[17:50] <AlexBreton> it has several
[17:51] <AlexBreton> has billions of synths
[18:00] Nick change: Fighter|brb -> Fighter|gone
[18:13] fnoble (n=fnoble@natreg.pem.cam.ac.uk) joined #highaltitude.
[18:14] fnoble (n=fnoble@natreg.pem.cam.ac.uk) left irc: Client Quit
[18:25] <DanielRichman> sbasuita, check out this bug
[18:25] <DanielRichman> * 220-magic-update-erlang.dpatch: Escape spaces in Erlang magic to avoid
[18:25] <DanielRichman> misidentifications, particularly PostScript files produced on Tuesdays
[18:25] <DanielRichman> (LP: #248619).
[18:25] <DanielRichman> That's brilliant
[18:26] <sbasuita> DanielRichman, interesting
[18:32] <Laurenceb> SpeedEvil: I managed to get hybrid to match the peroxide kerosene in performance
[18:32] <SpeedEvil> hmm
[18:32] <Laurenceb> and got the rocket GLOW down to 130Kg at the same time
[18:32] <SpeedEvil> this is with the 4th stage?
[18:32] <Laurenceb> the CF tube now has a 100% safety margin
[18:32] <Laurenceb> yes
[18:32] <Laurenceb> as opposed to 50% before
[18:33] <Laurenceb> the only tricky thing is a sort of throttleable regulator
[18:33] <Laurenceb> for the helium ullage pressurant
[18:35] <Laurenceb> then theres a simple injector bulkhead with a blow off cap, and a lower nozzle retainer one with solenoid valves built in for the TVC
[18:39] <SpeedEvil> does filling hte ullage with helium somewhat, then once it depressurises enough - empty another tank into it help?
[18:39] <SpeedEvil> oh - for throttling
[18:40] <Laurenceb> rough throttling
[18:40] <Laurenceb> if you just had regulators, there would be machining errors of several %, which would screw up attitude control
[18:41] <Laurenceb> also you can use the "throttling" to turn up the pressure and blow the cover plate on the injector face, to ignite the engine
[18:41] <SpeedEvil> hmm
[18:42] <Laurenceb> the postcombustion chamber is rather heavy :-S
[18:44] <Laurenceb> I think the engineering is easier - no complex bipropellant injector or motorised ball valves
[18:44] <SpeedEvil> yeah
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[18:45] <Laurenceb> just need a way to pressurise the He to 7000PSI
[18:45] <SpeedEvil> you mean on the ground?
[18:45] <Laurenceb> yes
[18:45] <SpeedEvil> pressure-washer
[18:45] <SpeedEvil> May need light modification to pump helium
[18:46] <Laurenceb> found a 600ml carbon cylinder mass 500grams thatd do
[18:46] <SpeedEvil> what's it for?
[18:47] <Laurenceb> firefighters
[18:47] <Laurenceb> - oxygen
[18:47] <SpeedEvil> :)
[18:47] <Laurenceb> interspiro
[18:48] <Laurenceb> 2Kg dry mass for each module
[18:51] <Laurenceb> ~500grams cylinder, 500 ablative nozzle, 400CF tube, 200 bulkheads, 200pipework, 50 cable, 50 helium, 100 other stuff
[18:52] <Laurenceb> theoretical ISP is considerably higher than kerosene for some reason
[18:54] <Laurenceb> *cough* some idiot is trying to have a plastic power BBQ outside
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[19:28] <Laurenceb> http://news.bbc.co.uk/1/hi/magazine/8107803.stm
[19:29] <jcoxon> indeed
[19:30] <Laurenceb> flaming arduino fans
[19:30] <jcoxon> haha
[19:37] <Laurenceb> http://imagebin.org/53031 <- 2300Km circular orbit :P
[19:37] <Laurenceb> you can see the 4th stage burn last a while
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[19:41] <Laurenceb> http://hackaday.com/ meanwhile.... more arduinos
[19:41] <Laurenceb> arggggg
[19:42] <natrium42> /s/arduino/atmel avr/
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[19:43] <Laurenceb> ftw
[19:44] <Laurenceb> and c compiler
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[19:50] <jcoxon> hey natrium42
[19:50] <natrium42> yo
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[20:02] <Laurenceb> fo sho
[20:02] <jcoxon> i think that we should just arduino'roll laurence with links
[20:02] <jcoxon> it'll make him go crazy
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[20:20] <G8KHW-2> I was thinking of making a micro-ZP balloon for test flights in the JetStream - UK regulation is such that it doesn't apply to small balloons - which do not exceed "2 metres in any linear dimension at any stage of its flight, including any basket or other equipment attached to the balloon;"
[20:20] <SpeedEvil> hmm
[20:21] <G8KHW-2> that would mean that such a balloon should have about 1Kg of lift in the jetstream?
[20:21] <SpeedEvil> where is the jetstream? 15Km?
[20:22] <G8KHW-2> around 10Km
[20:22] <G8KHW-2> + or -
[20:22] <SpeedEvil> 4m^3 at 10km would lift 400g or so.
[20:22] <SpeedEvil> I think
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[20:23] <G8KHW-2> still lots of lift to play with for a small payload
[20:23] <SpeedEvil> err
[20:23] <SpeedEvil> 1.4Kg or so
[20:24] <G8KHW-2> even better
[20:24] <SpeedEvil> http://www65.wolframalpha.com/input/?i=atmosphere+10km+density
[20:25] <SpeedEvil> lol
[20:25] <SpeedEvil> Though removing 'density' gives a sane result
[20:28] <Laurenceb> fly a tetroon
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[20:33] <G8KHW-2> Humm a 2m side tetroon has a volume of 1cu m by my calculation ((L / 2) ^ 3) ?
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[20:34] <G8KHW-2> not vey efficent in comparision with a sphere which would be a bit over 4 cu m
[20:36] <SpeedEvil> sphere is a bitch to make though
[20:36] <SpeedEvil> bulgy cube is quite simple
[20:36] <SpeedEvil> or bulgy tetroon
[20:45] <mc-> out of interest, how did you calculate 1.4Kg
[20:47] <mc-> if the density at 10km is 0.41kg/m^3, how can He lift 1.4Kg?
[20:51] <G8KHW-2> humm - yes I make it 1.6Kg = 0.41 * 4 cum for a 2m dia sphere
[20:52] <mc-> ok, I was basing it on a 1cu m volume
[20:53] <mc-> a few bin liners would make a cube shape
[20:54] <mc-> how would you make it float at 10km?
[20:54] <mc-> small vent hole which could be shut at float altitude?
[20:55] <mc-> I was thinking a bimetallic strip could be made into a primitive valve, which shuts at -50C
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[21:07] <jcoxon> hey all
[21:09] <mc-> hi jcoxon
[21:10] <mc-> did you see what G8KHW found out above?
[21:10] <jcoxon> yes
[21:10] <jcoxon> didn't know that
[21:10] <jcoxon> air navigation order is a complicated mess of regulations
[21:11] <mc-> if we can keep out of the main air routes that would help
[21:11] <mc-> plus a remote cutdown as well
[21:11] <jcoxon> unfortunately thats quite a bit of the UK
[21:12] <mc-> I don't mind losing a few payloads, the cost is so low.
[21:13] <mc-> send it out over the North sea
[21:14] <jcoxon> i think a valve system with a latex floater
[21:14] <jcoxon> is the way to go
[21:14] <jcoxon> a single use valve that we close when we reach ~ neutral bouyancy
[21:15] <mc-> latex should degrade during the day, so it would come down before night
[21:16] <jcoxon> how about if we launch in the evening
[21:16] <jcoxon> then we'd get a night and a day
[21:18] <mc-> yes, just wondering what the authorities would say about a balloon drifting at night?
[21:18] <jcoxon> there isn't any mention in the rules for meterological balloons
[21:18] <jcoxon> and we'd be aiming to keep it up above 40k ft or so
[21:18] <jcoxon> i think its worth keeping it out of the way of any planes
[21:19] <AlexBreton> I'm gonna call the CAA on Monday
[21:19] <AlexBreton> tomorrow if they're open
[21:19] <jcoxon> AlexBreton, what about?
[21:19] <AlexBreton> just to ask how you get permission to launch this stuff
[21:19] <jcoxon> you could ask us!
[21:19] <jcoxon> there is a form you need to fill in
[21:19] <AlexBreton> I assume we need some sort of permission
[21:19] <AlexBreton> where be it?
[21:19] <jcoxon> where are you planning to launch from
[21:20] <AlexBreton> cambridge
[21:20] <jcoxon> oh you don't need to worry then
[21:20] <AlexBreton> along with some UKHAS bods
[21:20] <AlexBreton> Reading is very close to H'row
[21:20] <jcoxon> yes, we have blanket permission
[21:20] <AlexBreton> what's this form called?
[21:20] <jcoxon> you don't need to do anything!
[21:20] <AlexBreton> really?
[21:20] <AlexBreton> great
[21:20] <jcoxon> just run it past G8KHW-2
[21:21] <jcoxon> then call up the local ATC 2 days before to warn them
[21:21] <jcoxon> then call 10mins before launhc
[21:21] <jcoxon> launch*
[21:21] <AlexBreton> you guys are allowed to shove any old crap into the air then?
[21:21] <jcoxon> within reason
[21:21] <AlexBreton> lol ok
[21:21] <AlexBreton> thx
[21:21] <jcoxon> if you want to launch from EARs contact G8KHW-2
[21:21] <jcoxon> if you want to launch from churchill contact edmoore
[21:21] <AlexBreton> yeah we are working with edmoore
[21:22] <mc-> jcoxon, any ideas for a simple one way valve?
[21:23] <jcoxon> yup
[21:23] <jcoxon> mc-, well not a one way valve
[21:23] <jcoxon> a one use valve
[21:23] <AlexBreton> bbl
[21:23] <jcoxon> one sec i'll draw it
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[21:24] <mc-> yes, one use. was thinking of something using a resistor heater and plastic.
[21:24] <jcoxon> yeah, i've sort of extended that a bit
[21:29] <mc-> is there an elastic material which works at -50C?
[21:29] <jcoxon> not sure
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[21:31] <mc-> I guess a metal spring still works
[21:34] <jcoxon> okay uploading
[21:35] <jcoxon> http://www.flickr.com/photos/jcoxon77/3641504463/
[21:35] <jcoxon> okay to explain
[21:35] <jcoxon> basically the bit that closes the valve is a disc with a solid bar down and then a ring
[21:36] <jcoxon> the main line threads from the side through the ring and as the payload is hanging off it keeps the 'plunger' but up out of the whole
[21:36] <jcoxon> we then cut this line say with nichrome
[21:36] <jcoxon> the payload then pulls the 2nd line tight which pulls down the plunger closing hte valve
[21:37] <mc-> I like it, but think it can be simplified a little more.
[21:37] <mc-> it's a fairly small hole that needs closing?
[21:37] <jcoxon> yes
[21:37] <jcoxon> need to workout the size of that
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[21:44] <Laurenceb> hi
[21:45] <natrium42> ih
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[23:38] <Laurenceb> grr stupid air
[23:38] <Laurenceb> air resistance really kills this
[23:38] <Fighter> stupid air? :p
[23:38] <Laurenceb> I cant get to orbit from 30km with air resistance accounted for
[23:39] <Fighter> You want to go to orbit from 30km? :o
[23:39] <Laurenceb> the problem with hybrids is your kind of set to a maximum burn time by the diameter
[23:39] <Laurenceb> yes
[23:40] <Fighter> Some kind of rocket under the balloon?
[23:40] <Laurenceb> yes, rockoon
[23:41] <Fighter> Ah yeah, I think I read the article on the wiki
[23:41] <Fighter> You want to get something actually orbiting, or just reach orbit?
[23:42] <Laurenceb> I'm trying to design something to launch a 1Kg class cubesat
[23:43] <Fighter> Ah yeah, cubesats are interesting. I guess your strategy would dramatically reduce the cost of launch
[23:44] <Fighter> Anyway, I'm off for the night
[23:44] <Fighter> Cya
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[23:49] <SpeedEvil> Laurenceb: can restarts fix this?
[23:49] <Laurenceb> a bit.. just trying
[23:49] <SpeedEvil> Laurenceb: assuming that you have aerodynamic control when you have drag
[23:49] <Laurenceb> its all with the first stage
[23:50] <Laurenceb> theres an optimum burn time that'll take you up to 120Km or so with the first stage
[23:50] <Laurenceb> then your free of the atmosphere
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[23:51] <SpeedEvil> Though restarts of course add lots of other nasty issues
[23:51] <SpeedEvil> I mean multiple restarts+coasts of the bottom stage
[23:51] <Laurenceb> maybe I screwed something up - this is rediculously bad
[23:52] <Laurenceb> doh
[23:53] <Laurenceb> didnt divide the drag impulse by mass
[23:53] <SpeedEvil> :)
[23:53] <Laurenceb> yes, wolfram alpha said it would work ok
[23:54] <SpeedEvil> out of interest, what sort of query string are you using
[23:54] <Laurenceb> I just stuck in an equation for density
[23:55] <SpeedEvil> Ah - I thought you meant you had it doing the whole model
[23:56] <Laurenceb> yeah orbit
[23:57] <Laurenceb> tho it is between 135Km and 1800Km
[23:57] <Laurenceb> annoyingly the burn time is probably too long for hybrids
[23:58] <Laurenceb> 100 seconds
[23:58] <SpeedEvil> that's what - the second stage?
[23:58] <Laurenceb> all the stages
[23:59] <Laurenceb> I kept it the same
[00:00] --- Sat Jun 20 2009