highaltitude.log.20070417

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[13:16] <Laurenceb> Hi folks
[13:16] <Laurenceb> got the glider back today
[13:16] <edwardmoore> ooooooh
[13:16] <edwardmoore> pictures and gossip etc
[13:16] <Laurenceb> well its very smashed ;)
[13:17] <Laurenceb> rocketboys radio will live
[13:17] <edwardmoore> plummeted then?
[13:17] <Laurenceb> well one wingtip is smashed off
[13:17] <Laurenceb> so I'd say it spiral dived
[13:18] <Laurenceb> the flight computer board is cracked in half, but I should be able to get it working
[13:18] <edwardmoore> that's a shame- really must have been a hard hit then
[13:19] <Laurenceb> the battery was pulverised, its no wonder we couldnt recieve anything
[13:19] <edwardmoore> so you lost signal after impact?
[13:20] <Laurenceb> yes, we drove only 10 meters away from the landing site
[13:20] <edwardmoore> bugger
[13:20] <Laurenceb> spiral diving is the only way it could have come down so fast
[13:21] <edwardmoore> yeah agreed
[13:21] <Laurenceb> it couldnt have simply dived like that, there would have been too much lift
[13:21] <Laurenceb> and the damage seems to correlate
[13:21] <edwardmoore> so maybe you could have a rate gyro and deployable chute on the next one?
[13:22] <Laurenceb> sprial diving in a clockwise direction
[13:22] <Laurenceb> well, I'd say thermopiles are needed on a rigid glider
[13:22] <edwardmoore> the chute could work anyway to bring it down, could also fire if it starts spiralling out of control
[13:22] <Laurenceb> yes
[13:22] <edwardmoore> sozzle, pinger just went for lunch. bbl.
[13:23] <Laurenceb> but I wouldnt trust a rate gyro alone
[13:23] <Laurenceb> accept on a rogallo or parafoil
[13:24] <Laurenceb> cya later
[13:34] <edwardmoore> back
[13:34] <edwardmoore> why not?
[13:36] <Laurenceb> well, I'd like to have 2 axis stabilization
[13:36] <Laurenceb> oh any future rigid gliders
[13:37] <Laurenceb> rogallos and parafoils seem to be more stable, so single axis would be acceptable
[13:37] <edwardmoore> ok sure. but for purely 'we're fucked fire the chute' stuff, a single one would suffice surely?
[13:38] <Laurenceb> yes, but its best not to waste time launching stuff when you know it could go badly wrong
[13:38] <Laurenceb> rogallo especially seem inherantly more stable
[13:38] <edwardmoore> lol, tue :)
[13:38] <edwardmoore> true*
[13:39] <Laurenceb> but a 2 axis thermopile stabilised glider wouldnt be bad
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[13:40] <Laurenceb> I'll probably build a rogallo or work on a parafoil with jcoxon, rocketboy,and phatmonkey
[13:40] <edwardmoore> uhuh
[13:40] <Laurenceb> the good news is the gps looks undamaged so it can go straight onto ultrahab
[13:42] <edwardmoore> do you have a vague launch date for that?
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[13:42] <Laurenceb> I watched jcoxons video of parafoil control, but I wasnt convinced by the angle of attack control
[13:42] <Laurenceb> erm july probably
[13:42] <edwardmoore> which video was that?
[13:42] <Laurenceb> I have exams in june
[13:43] <Laurenceb> he put it up a couple of weeks ago
[13:43] <edwardmoore> on the wiki?
[13:43] <Laurenceb> on pegasus hab project
[13:44] <edwardmoore> i'm guessing it's probably not linked to
[13:44] <Laurenceb> well basically you have two arms, one on either side of the payload
[13:44] <edwardmoore> oh that
[13:44] <Laurenceb> and they are connected to servos
[13:45] <Laurenceb> yes, I can see it will work very well for turning
[13:45] <edwardmoore> i never built that with a view to it being sued properly, it was just a way of doing independant steering and angle or attack with the two servos i had at the time
[13:45] <edwardmoore> sued = used
[13:45] <Laurenceb> but if you try to control the angle of attack the payload will just rotate
[13:46] <edwardmoore> nope
[13:46] <Laurenceb> sued lol, lucky my glider didnt hit any of the cars in e carpark
[13:46] <edwardmoore> the cg was low enough to provide suffiecient moment
[13:46] <edwardmoore> it worked
[13:47] <edwardmoore> but it was a bodge- i only really wanted steering to keep it away from james' pond when we tested it at his place
[13:47] <Laurenceb> well yes, but the c of g of the payload has to be below the servos
[13:47] <Laurenceb> thats the only thing that provides any moment
[13:47] <edwardmoore> yup. so what's your point?
[13:48] <Laurenceb> well its much better at steering than angle of attack control thats all
[13:48] <Laurenceb> or so it would appear, how well did it work?
[13:48] <edwardmoore> it worked fine for the testing we wanted it for
[13:49] <Laurenceb> hmmm, how fast would it turn?
[13:49] <edwardmoore> i wouldn't want that kind of actuator cross-coupling in the real thing though
[13:49] <edwardmoore> oh we could get it to spin sufficiently fast to collapse :)
[13:49] <edwardmoore> more than fast enough
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[13:50] <Laurenceb> mhh not good, but servo limits and arm lenght would stop that
[13:50] <edwardmoore> the limits are set by the stall angles of the parafoils. the servos can more than handle it
[13:50] <Laurenceb> hmm, so could you control the glide speed?
[13:50] <edwardmoore> we had something like 40 degrees of sweep. in the real world i wouldn't want more than 10
[13:51] <Laurenceb> what effect did it have?
[13:51] <edwardmoore> in as far as angle or attack controls it, yes. but i want do test with a different parafoil section
[13:51] <edwardmoore> what effect did what have?
[13:52] <Laurenceb> attack angle control
[13:52] <Laurenceb> ie what sort of ratio of speeds could you reach
[13:52] <edwardmoore> well it mainly affects glide ratio
[13:52] <edwardmoore> and for the real thing we'd want to keep it just shy of stall and leave it at that
[13:52] <Laurenceb> interesting
[13:53] <Laurenceb> so if you stall does it come down like a regular parachute?
[13:53] <edwardmoore> if you stall the chute it collapses
[13:53] <Laurenceb> oh :(
[13:53] <edwardmoore> you plummet for a bit and it sorta rights itself again
[13:54] <Laurenceb> ah I see
[13:54] <Laurenceb> this is what I've been investigating with rogallos
[13:54] <Laurenceb> using it like a parachute for final descent
[13:55] <edwardmoore> yeah
[13:55] <Laurenceb> so it doesnt look like it would really work with a parafoil
[13:55] <edwardmoore> well we were thinking of deploying a seperate chute for final descent
[13:55] <Laurenceb> yes, but more weight and stuff to go wrong
[13:56] <Laurenceb> surely youd want the minumum possible angle of attack, so it glides fast
[13:56] <edwardmoore> hmm i'm not sure i agree with you there. it's more of an n+1 redundancy
[13:56] <Laurenceb> true
[13:56] <edwardmoore> no, you want the most lift which gives you the greatest range
[13:57] <edwardmoore> bear in mind it'll be quite a small and fast parafoil rather than a big parachutey one
[13:57] <Laurenceb> I see, so small parachute > fast
[13:57] <Laurenceb> and high angle of attack > efficient
[13:58] <edwardmoore> something like that
[13:59] <edwardmoore> but at least if it goes tit-up, it'll still fall under a chute/parafoil
[13:59] <edwardmoore> just like any other unguided paload
[13:59] <Laurenceb> I'd say you want it faster than the difference between peak gust speed and average speed
[14:00] <edwardmoore> well yeah, if we can't cut into wind sufficiently then we have a problem
[14:00] <Laurenceb> that way if you use guidance with wind compensation it wont get airspeed vectors pointing in the opposite direction
[14:00] <Laurenceb> when your heading into the wind
[14:01] <Laurenceb> although you still wont be making progress against the wind
[14:02] <edwardmoore> we'll be limited on what weather we can launch it into, for sure
[14:02] <edwardmoore> but it should cope on most balloon-type-weather days
[14:02] <Laurenceb> yes, this is the worst case where it will not only get dragged backwards by the wind, but the guidance will lose control in the gusts
[14:03] <edwardmoore> well yeah, if you saturate the control system you saturate the control system. what can you do?
[14:04] <Laurenceb> I did some of the glider tests with 10 knot gusts and the glider coped,- it flew at 20 knots
[14:05] <edwardmoore> i would hope we could deal with 10 knots, otherwise we really would have to pick our days carefully
[14:05] <Laurenceb> but you can see on some of the tests, oscillation seems to appear later in the flight, that was wind gusts driving it at the oscillation frequency
[14:06] <Laurenceb> but with a rate gyro there shouldnt be any oscillation, and the rate gyro wont even pick up gusts
[14:07] <Laurenceb> unless they turn the payload
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[14:08] <Laurenceb> wish I had a bigger hill, then I could have done longer test flights
[14:10] <mc-> hi all, I just bought 5 18" and 2 36" chutes. How about a glider test that has an emergency chute?
[14:12] <Laurenceb> might be a good plan
[14:12] <Laurenceb> youd have to have room
[14:12] <Laurenceb> I ran into problems with my tests as there is a housing estate at the bottom of the hill where I was flying
[14:13] <Laurenceb> on some of the longer tests it flew into peoples gardens
[14:14] <edwardmoore> lol
[14:14] <edwardmoore> yeah problem
[14:14] <mc-> Should I get a foam wing, or a rogallo ?
[14:14] <edwardmoore> well you could make more of the fuselage out of a tube that deploys the chute
[14:14] <edwardmoore> and then have the tronics infront of it
[14:15] <edwardmoore> ms- for what purpose?
[14:15] <mc-> The chutes are tiny btw
[14:15] <Laurenceb> good plan
[14:15] <Laurenceb> you can make chutes out of polythene, its very easy
[14:15] <Laurenceb> heat seal it with a soldering iron
[14:15] <mc-> my chutes were $3 each
[14:16] <Laurenceb> nice, I'm only going for homemade chutes as they're lighter
[14:16] <Laurenceb> mc- do you have a good launch site?
[14:16] <edwardmoore> lil bit weaker though
[14:17] <edwardmoore> if the glider has some speed up and you deploy it, you may well rip them
[14:17] <Laurenceb> strong enough for ultrahab
[14:17] <edwardmoore> fair enough
[14:17] <mc-> I'm sure I can find a site
[14:17] <mc-> but don't have time usually. So I prefer to build electronics and ask someone else to test
[14:17] <Laurenceb> I'd suggest big steep hill :)
[14:19] <mc-> LB, if I built electronics+chute, could you test a rogallo?
[14:19] <Laurenceb> hmm good plan
[14:19] <mc-> wait until exams are over
[14:19] <Laurenceb> But i'm
[14:19] <Laurenceb> yes
[14:19] <Laurenceb> arg exams...
[14:20] <mc-> returning payloads to a launch site could save us all loads of time
[14:20] <Laurenceb> I wouldnt really need a chute for my rogallo
[14:20] <mc-> good point
[14:20] <Laurenceb> the plan is to use the rogallo as a chute
[14:21] <mc-> can the rogallo be made so it can be deployed? (I thinking of a rocket boosted deploying wing)
[14:21] <Laurenceb> if it worked it wood look very cool, rogallo gently lowers itself down
[14:21] <Laurenceb> well, thats hard
[14:22] <Laurenceb> you could fold it up
[14:23] <Laurenceb> but if you launch at very high altitude, the air is thin, so a rogallo with rockets on might work by itself
[14:24] <Laurenceb> say 30km, a rogallo could easily reach 100 knots
[14:24] <mc-> true, for a first test, it doesn't matter if the rogallo is deployed.
[14:24] <Laurenceb> youd really need a parawing, but rogallos are easier to test
[14:25] <Laurenceb> and can land almost vertically
[14:26] <mc-> my suggested plan is 1. get a rogallo to work by radio control 2. get it autonomous
[14:26] <Laurenceb> have you seen my big rogallo on the wiki?
[14:26] <mc-> what's the link again?
[14:26] <Laurenceb> thats RC but I havent got it working under RC control
[14:27] <mc-> I can do the radio part
[14:27] <Laurenceb> http://wiki.ukhas.org.uk/projects:mihab:glider
[14:28] <Laurenceb> I've got Rc on it, but my control "rigging" wasnt very good, and the envelope was torn, so its being rebuilt
[14:28] <Laurenceb> it glided ok
[14:29] <mc-> that's big
[14:29] <Laurenceb> 1 meter long sides
[14:29] <mc-> is it rugged enough to survive a rough landing?
[14:29] <Laurenceb> yes its very strong
[14:30] <Laurenceb> the frame is light and the payload hits the glound first, so there isnt much force on the frame
[14:32] <Laurenceb> its made a 1cm pine dowel and 12 micron polythene sheet, only weighs about 300 grams
[14:32] <Laurenceb> a=of
[14:32] <mc-> Shall I build some electronics that reports GPS every sec, and a receiver to get servo commands?
[14:33] <Laurenceb> oh so we can fine tune some sim code?
[14:33] <mc-> would like ukhab to be the first group to have a payload that returns to base
[14:34] <Laurenceb> ie record servo inputs and gps heading + position ?
[14:34] <Laurenceb> then use it to write sim code, like for my glider?
[14:34] <mc-> yes, something like that
[14:35] <Laurenceb> I think its a very good technique
[14:35] <mc-> give me a month or so.
[14:36] <mc-> plus a radio can be used to send a cutdown command
[14:36] <Laurenceb> saves tons of faffing about half way up a hill, and quite basic sim code gives descent results
[14:36] <Laurenceb> yes I've got exams, so wnt be free till the summer
[14:37] <mc-> I've got a radio that should go 10+ miles line of sight with a 0.1W transmitter.
[14:39] <Laurenceb> neat
[14:39] <Laurenceb> I was looking on ebay and you can pick up 1.5W 2.4 GHZ video transmitters
[14:40] <mc-> but I think they needs yagis to get good signals.
[14:40] <Laurenceb> with an old analogue sky dish and a 2.4 ghz reciever, you might be able to get live video from a balloon
[14:41] <mc-> I prefer to record video on a dig cam.
[14:41] <Laurenceb> -yes, I was thinking about for a rocket launch
[14:41] <mc-> I know some rocket guys that have great video from 2.4
[14:42] <Laurenceb> I met some people at oxford who were fitting 2.4 ghz cameras on birds
[14:42] <mc-> I'm prepared to lose everything on each launch, are 2.4 stuff expensive?
[14:43] <Laurenceb> very cheap, I've got a fair bit
[14:44] <Laurenceb> you could probably get everything for a ballon for less than £20
[14:44] <mc-> I'm on the yahoo ballooning group, they just got a record 777 mile contact from a balloon.
[14:44] <Laurenceb> sweet
[14:44] <Laurenceb> I want to run IRC over a balloon
[14:45] <Laurenceb> from 24km you could relay from ireland to denmark
[14:46] <Laurenceb> using 10mw at 433MHz, if you assume line of sight + a little bit extra
[14:46] <Laurenceb> and from our experiences with 433MHz, that range might be possible
[14:47] <mc-> in the US, they have plenty of power, 10mw is a lot less power, need narrow bandwidth
[14:48] <Laurenceb> grr stupid eec regulation
[14:50] <mc-> does your wing have a working servo etc?
[14:50] <mc-> how do you steer now?
[14:51] <Laurenceb> well can you see the balsa wood arm at the back?
[14:51] <Laurenceb> thats glued onto a servo, and moves the c of g left or right
[14:51] <Laurenceb> by pulling on the guy lines
[14:52] <mc-> ok, looks good, and I see a RC txer, so I guess it's RC
[14:52] <Laurenceb> but the guy lines need to be connected to the fram closer to the center for it to be effective, when I rebuild it thats what will happen
[14:52] <Laurenceb> yes, but I havent flown it under RC
[14:53] <Laurenceb> fram=frame
[14:53] <Laurenceb> also there is no pitch control, so I'm going to add that as well
[14:55] <mc-> don't worry about pitch for the moment, let's it flying and steering under radio control.
[14:56] <Laurenceb> well I want to try out making it capable of vertical descent at some point
[14:56] <mc-> I see. I've gotta go now.
[14:56] <mc-> cya
[14:56] <Laurenceb> cya then
[14:57] <Laurenceb> http://cgi.ebay.co.uk/1500mW-Long-Range-Wireless-Transmitter-for-Camera-UK17_W0QQitemZ290100734296QQihZ019QQcategoryZ48636QQrdZ1QQssPageNameZWD4VQQcmdZViewItem
[14:58] <Laurenceb> that should be powerful enough :)
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[16:42] <edwardmoore> hi jcoxon
[16:42] <jcoxon> hey edwardmoore
[16:43] <edwardmoore> all well?
[16:43] <jcoxon> yup
[16:45] <jcoxon> and yourself?
[16:45] <edwardmoore> not so bad
[16:45] <edwardmoore> gently working :)
[16:51] <jcoxon> hehe
[16:51] <jcoxon> i've had a little break from working
[16:51] <jcoxon> going to start again tomorrow
[16:58] <edwardmoore> lol
[16:59] <edwardmoore> probably good for the soul
[17:08] <Laurenceb> I've found a car battery :)
[17:08] <Laurenceb> I'll put it on my peltier later
[17:22] <Laurenceb> http://www1.dfrc.nasa.gov/Gallery/Movie/Paresev/640x/EM-0022-02.mov
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[17:58] <Laurenceb> http://www.youtube.com/watch?v=sswv4WUi0aY
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[00:00] --- Wed Apr 18 2007