high altitude balloon project
Jake Anderson
thing provided we fit inside some limitations
I suggest we hit up some local high altitude balloon people for info on
getting it past casa
http://projecthorus.org/
seems like a good place to start.
I suggest we list things we want to achieve then work out how to get there.
i would like to set an amateur altitude record ;->
I would like to try hydrogen for lift gas.
I would like some high resolution shots of earth and space.
I would also like to try active envelope control so we can have the
envelope maintain approximately the same size for the entire flight,
this should make the ascent *much* faster hence reducing drift and with
a non latex balloon give a higher maximum altitude.
guided recovery would be nice too.
I can see a few launches being involved in getting there, starting with
a bog standard camera in an eskie ;->
Max Nippard
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David Lyon
Jason Ball
Don't you mean OpenWRT ?
David Lyon
tALSit de CoD
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Jake Anderson
GPS and telemetry can be done too.
On 02/24/2012 04:42 PM, tALSit de CoD wrote:
Yeah, that's what I want to do.
On 24 February 2012 15:23, Max Nippard <mnip...@gmail.com> wrote:
Photos is my main goal, but extras like a down looking hemispherical panorama and the active envelope control and guided recovery would be fun to try.
On 24 February 2012 15:13, Jake Anderson <groo...@gmail.com> wrote:
i don't believe the regulatory burden is that great for this kind of thing provided we fit inside some limitations
I suggest we hit up some local high altitude balloon people for info on getting it past casa
http://projecthorus.org/
seems like a good place to start.
I suggest we list things we want to achieve then work out how to get there.
i would like to set an amateur altitude record ;->
I would like to try hydrogen for lift gas.
I would like some high resolution shots of earth and space.
I would also like to try active envelope control so we can have the envelope maintain approximately the same size for the entire flight, this should make the ascent *much* faster hence reducing drift and with a non latex balloon give a higher maximum altitude.
guided recovery would be nice too.
I can see a few launches being involved in getting there, starting with a bog standard camera in an eskie ;->
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Terry Dawson
> Yeah, that's what I want to do.
> What are the main ways of actually recovering one of these devices?
At linux.conf.au this year, Dave (shig) decided on a whim to do a
balloon launch, so with a budget of $200 and 100 grams we assembled
gas, android phone and balloons. Dave jury-rigged the guts of the
phone with simple software to take photos and SMS the location. The
thing literally took a matter of hours to organise and we launched the
thing.
Unfortunately we launched it on a cloudy day, and in cloud, so it
tracked the cloud and we have some great cloud photos .. lots of
photos of clouds.
But we recovered the thing and have a cool Google map showing it's path.
It was a lot of fun.
Terry
Jason Ball
David Lyon
With a TP-link router, usb-webcam and gps (5v data) you may be able to
get it all to go together in one small bundle.
Clever winding of the antenae might help but skill deficient in that field.
I hacked my holux gps to tx data over usb. No brainer but it does work.
On 2/24/12, Jake Anderson <groo...@gmail.com> wrote:
> radio direction finding with a xmitter on the payload is the "gold
> standard" (it also helps you work out which tree its in)
> GPS and telemetry can be done too.
>
> On 02/24/2012 04:42 PM, tALSit de CoD wrote:
>> Yeah, that's what I want to do.
>> What are the main ways of actually recovering one of these devices?
>> // talsit.org <http://talsit.org>
>>
>>
>> On 24 February 2012 15:23, Max Nippard <mnip...@gmail.com
>> <mailto:mnip...@gmail.com>> wrote:
>>
>> Photos is my main goal, but extras like a down
>> looking hemispherical panorama and the active envelope control and
>> guided recovery would be fun to try.
>>
>>
>> On 24 February 2012 15:13, Jake Anderson <groo...@gmail.com
>> <mailto:sydney-h...@googlegroups.com>.
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Jake Anderson
the ground and when it lands in a tree upside down they become iffy.
hence RDF and beacons being used.
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tALSit de CoD
// talsit.org
David Lyon
Apparently it transmits better upwards than sideways.
Hi power wifi antenae can do up to 10km line of site.
How well it works in the air would be the interesting question to answer.
On 2/24/12, tALSit de CoD <tal...@talsit.org> wrote:
> If I assume that I will have absolutely no GSM or other type of network,
> RDF would be the way for me to go.
> What's a cheap/easy option that you can imagine being feasible?
> // talsit.org
>
>
> On 24 February 2012 16:44, Jake Anderson <groo...@gmail.com> wrote:
>
>> **
Gav
Jake Anderson
they get 60+ miles range with basic antennas.
they are in the 900mhz range though so i dunno how that'd work with the
regs here.
some kind of uhf/vhf beacon with telemetry in a ham band is probably the
best bet.
David Lyon
You can transmit a very short signal with high-energy as long as it's
for a short time.
So if there's no carrier to tx, clever things can be done while staying legal.
On 2/24/12, Jake Anderson <groo...@gmail.com> wrote:
Terry Dawson
> I didn't say it didn't work in 3d, but when the payload is tumbling to the
> ground and when it lands in a tree upside down they become iffy.
> hence RDF and beacons being used.
Ours landed in a tree. Google Maps showed us the tree.
Terry
Madox
It might even look like we're not selfishly looking for cool photos hehehe...
Jason Ball
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Jake Anderson
> Maybe I am just looking for an excuse to buy a bunch of varying gas sensors... But I would like a scientific package of sorts to go up with the balloon. 10 types of gas sensors, temperature sensors etc etc baselines against sea level in a city and at launch site would be interesting I think.
>
> It might even look like we're not selfishly looking for cool photos hehehe...
>
1) because it sounds cool
2) WE CAN HAVE FRIKKIN LAZOR BEAMZ !!!one
one thing to remember, every gram you add to it means it wont go as high :-<
Jason Ball
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Terry Dawson
> Maybe I am just looking for an excuse to buy a bunch of varying gas sensors... But I would like a scientific package of sorts to go up with the balloon. 10 types of gas sensors, temperature sensors etc etc baselines against sea level in a city and at launch site would be interesting I think.
>
> It might even look like we're not selfishly looking for cool photos hehehe...
The heavier the payload, the steeper the approvals required for launch.
Terry
Madox
David Basden
I call shenanigans.
David Lyon
A friend of mine did a radio based fire alarm system that transmitted
4 bytes to uniquely identify which fire alarm went off.
Some time ago now, but it was legal then.
Jason Ball
no, saving lives.
A friend of mine did a radio based fire alarm system that transmitted
4 bytes to uniquely identify which fire alarm went off.
Some time ago now, but it was legal then.
David Lyon
Just go with what you know and feel comfortable about making work.
> vk2...@google.com <vk2...@google.com>
> callsign: vk2vjb
Jason Ball
Matthew Chapman
spectrum licenses I've ever read specify a limit on *peak* EIRP
amongst other things. Besides, if you're sending narrow bursts, you
need to be really careful how you shape the envelope or you're going
to be spewing shit all over the spectrum. The extreme case is a spark
gap transmitter, and no, they're not legal.
Just because people get away with dodgy shit sometimes doesn't make it legal ;)
Matt
Matthew Chapman
doing it, R&D should do it better.
It looks like the current amateur radio high altitude ballooning
record is 136,545ft [1]. I did some back of the envelope calcs. At
137,000ft we're talking something like ρ=0.003kg/m^3 air density,
T=-17°C and p=219Pa [2]. At apogee we have:
mass of air displaced = mass of balloon + mass of payload + mass of gas
ρV = m_b + m_p + (pV/RT) M
i.e. (ρ - pM/RT) = (m_b + m_p) / V
where I've rearranged it so the left hand side is a function of
altitude and the type of gas in the balloon [3], and the right hand
side is a function of balloon and payload.
To reach the desired altitude, the target for the value of the right
hand side is 0.003 kg/m^3 or lower (and preferably more like 0.0028 in
order to account for the mass of the gas).
What we need, then, is a balloon that's very large at its bursting
point but as light as possible (duh? didn't need maths to conclude
that ;)). It doesn't even matter if it's thin and its range of
expansion is small, I can think of a couple of potential solutions -
either some sort of active envelope control like Jake suggests [4], or
stuffing it inside a first stage balloon - unfortunately it's unlikely
any standard commercial balloons will be designed like that.
I've started to put together a spreadsheet of weather balloons:
https://docs.google.com/spreadsheet/ccc?key=0Agv0rYcIyuU3dDFxcUlCMFoyQnRoVHRFaDhRTEM3b3c
Only one of the balloons I've catalogued so far met the 0.003 target,
and only barely, so by the time you add a payload it's questionable.
I'm sure there's plenty more out there, though - that 30' balloon is
only 1200g and a lot of other groups are using 1500g and 2000g
balloons which are probably larger than 30'. Feel free to edit the
spreadsheet as you find more.
Of course, there will be variation in both the exact bursting point
and atmospheric conditions, so reality will vary - and I'm sure chance
was involved in many of the records - but it would be good to be able
to reach 137,000-ish on paper. If the payload can be made light that
will be a key differentiator.
M
[2] http://www.digitaldutch.com/atmoscalc/
[3] ρ/p/T are air density/pressure/temperature, M is molecular weight
of gas in balloon [2 for H2, 4 for He], R is gas constant, m_b and m_p
are masses of balloon and payload, V is volume of balloon at bursting
point
[4] While in principle I like the idea of active envelope control, the
pressure change over the ascent is almost three orders of magnitude,
so in order to keep the envelope constant we'd need to put perhaps
500x more hydrogen into the balloon, only to vent it out the bottom...
we may find good reasons for doing it partially, but my gut feeling
is that it's more important to keep the payload light, because a light
payload will increase the altitude, whereas active envelope control
probably won't (unless it can allow use of a significantly thinner
balloon).
Andrew
"PING", what else could you possibly need?
GDR (Grinning, Ducking, and Running)
Anon.
Jake Anderson
One of the reasons i like active control is we can use a non elastic balloon my gut feel is that right at the top the increase in pressure caused by the latex squishing the gas would become signifigant. I believe thats why regular high altitude balloons use inelastic envelopes with just a puff of helium in them at launch.
The other main reason is so we can minimise the time spent getting to altitude.
And yes weight is the enemy.
My plan was something like a .2mm carbon fiber shell in the shape of a lifting body(better surface area to volume), with 2 elevons as the payload fairing. Insulate with aerogel so the electrics dont freeze
An active controller could be as simple as a long tube of envelope material with a rubber band around it. If the pressure inside is greater than outside it'll vent.
If we make the envelope out of a non uv stabilised material it should decay pretty readily up there and after it hits the ground and we wont need something to deflate the balloon. I wonder if the hydrogen would burn at that altitude ;-)
Sent from my HTC
https://docs.google.com/spreadsheet/ccc?key=0Agv0rYcIyuU3dDFxcUlCMFoyQnRoVHRFaDhRTEM3b3c
M
[2] http://www.digitaldutch.com/atmoscalc/
[The entire original message is not included]
Matthew Chapman
may end up in the too hard basket for mission #1. My main concern was
about where one would get (or how one would make) such a thing.
I'm not sure if your carbon fiber suggestion was for the envelope
itself... but the weight is much too high for that application I
reckon (even at 0.2mm thickness it would weigh about 350g per square
metre, if my calculation is right, whereas the candidate latex balloon
is about 5g per square metre). Also to carry even a modest payload of
say 200g, the envelope will need to be really big - order of 10m
diameter at burst point - so building it out of something rigid will
be problematic to transport.
You're right that the difference in pressure inside due to the latex
balloon is probably significant - I realised I hadn't modelled that
just after I sent my email, it just means that p needs to be the
pressure inside rather than the pressure outside. I'll see if there's
enough data available to estimate this. It will probably make the gas
density term (pM/RT) significant whereas I had assumed it wasn't
significant compared to the air.
The limiting altitude is still determined by mass/volume ratio at
bursting but it means that, for a elastic balloon, you need to pump
more gas into the balloon on the ground to achieve the desired volume
at apogee, and that then affects the mass of the whole thing.
M
2012/2/25 Jake Anderson <groo...@gmail.com>:
Jake Anderson
> Yep - a non-elastic balloon would be worth looking into, although it
> may end up in the too hard basket for mission #1.
weather balloon set for a , lowish latitude burst so we dont have to
traipse across half of nsw looking for it
> My main concern was
> about where one would get (or how one would make) such a thing.
> I'm not sure if your carbon fiber suggestion was for the envelope
> itself... but the weight is much too high for that application I
> reckon (even at 0.2mm thickness it would weigh about 350g per square
> metre, if my calculation is right, whereas the candidate latex balloon
> is about 5g per square metre). Also to carry even a modest payload of
> say 200g, the envelope will need to be really big - order of 10m
> diameter at burst point - so building it out of something rigid will
> be problematic to transport.
I do wonder if we could steer the ascent somewhat by offsetting the payload.
Matthew Chapman
> thin weldable plastic methinks
I've been doing a bit of reading and it seems the plastic of choice in
the scientific community is polyethylene film, probably because of how
widely available it is.
ISAS in Japan achieved 53km (~174,000ft) in 2002 using a balloon made
of 3.4um thick polyethylene film. Their balloon volume was 60,000
m^3, which is an equivalent spherical diameter of about 48m - though
of course these balloons are rarely spherical because it's too hard to
join the film in that shape - and carried a payload of 5kg.
Of course I'm not suggesting targetting 174 Kft or a 50m balloon
anytime soon, let's aim for the amateur record first ;) But it shows
what's theoretically possible.
(Just to put their achievement in perspective, the air density at
174Kft in the standard atmosphere is 0.0007 kg/m^3, which is >4 times
more rarefied than the 0.003 kg/m^3 at 137Kft.)
M
chris bate
potentially a multistage balloon what i would like to do with one is make the payload a gps guided glider so that it can glide it's way down and home again, plus also provide some stability for some nice photos
M
Luke Weston
I think Jason's board is the best way to go. It's the mobsendat, yet?I was toying with buying one of those for myself :)I've got a pair of 60mW Xbees if that helps (it's apparently got the mountings), but I doubt they've got sufficient range. I curse them with lightscythe stuff on a regular basis...
Jason Ball
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Andrew
Matthew Chapman
>
> One of the reasons i like active control is we can use a non elastic balloon my gut feel is that right at the top the increase in pressure caused by the latex squishing the gas would become significant.
I worked through the physics, and yes you are absolutely right, it
becomes fairly significant at high altitude. The elastic pressure of
a typical weather balloon is something like 100-200 Pa. So at 137,000
ft when your external pressure is also around 200 Pa, it might squish
the gas by a factor of two compared to a zero-pressure balloon. (So
hydrogen becomes like helium density-wise, and helium becomes pretty
crappy.) This can be reduced by a good choice of balloon though - the
thinner and larger the unstretched balloon is, the less the squishing.
For anyone interested in the physics I wrote it up here:
http://www.zmatt.net/weather-balloon-physics/
I deliberately didn't run the example up to the sort of altitude we
are after, since I didn't want to give away too many secrets ;) But I
have the Octave code to do the simulation for any given balloon.
Ultimately non-elastic balloons will always have a higher ceiling for
a given size. They're a bit unwieldy though because they have that
size at ground level, and they don't automatically pop. So if we can
get elastic balloons that have the right properties to achieve the
target altitude, it's more convenient.
Also, if we want to set a record at some point, an interesting thing
to consider is how to optimise for the best day/time/place. e.g.
possibly launching before sunrise on a cold high-pressure winter day.
A sunrise would make for some cool photos too.
Does anyone know where to get Australian atmospheric data at different
altitudes (e.g. radiosonde measurements)?
Matt
Gav
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Jake Anderson
here have one of these
;->
as a firm believer in "pics or it didn't happen" I say we need something like a gopro in it
apparently they weigh 100 grams
If we have a payload of say 500 grams, that should be enough to do pretty much everything we want to do including steered ascent if we are lucky.
how big a balloon would we need to loft that to say 145kft 100kft and say 50kft (in a zero pressure balloon)?
(i suggest we start small and try to make sure we can get the darn thing back ;->)
Ada Lim
On Feb 27, 11:54 pm, Matthew Chapman <enof...@gmail.com> wrote:
> Does anyone know where to get Australian atmospheric data at different
> altitudes (e.g. radiosonde measurements)?
looking for? I saw example ones as part of my training manuals but
since I don't go above 5000ft I don't really pay attention.
-A
Michael Molloy
I have some gear from my RC stuff which includes Autopilots, OSD video cams video TX and Rx (not huge power), GPS, GoPro..
Might be able to get weather balloons too.
Mick
--
Nick Johnson
i know it sounds a little on the nuts side but what about a bunch of partially inflated condoms, if you inflated a few of them enough to carry a small payload but still allowed for some massive expansion of the containing gas as it gets higher and higher,
potentially a multistage balloon what i would like to do with one is make the payload a gps guided glider so that it can glide it's way down and home again, plus also provide some stability for some nice photos
Madox
Max Nippard
Ada Lim
On Feb 28, 12:55 pm, Nick Johnson <arach...@notdot.net> wrote:
> I love the idea of launching an autonomous glider as a payload. I've seen
> it done before, and it'd be really cool to do it ourselves.
I don't remember enough about high altitude flight to be completely
confident coming up with a design that can work in the upper upper
atmosphere.
I just reread the bits of CASR101. if it's <100gm, it's a "micro UAV"
and is essentially unregulated. if it's >100gm, it's a "model
aircraft" and requires permission to be flown above 400ft out of
direct visual contact.
so the challenge will be getting a glider that can handle being in the
upper atmosphere that fits under 100gm. that will be fun.
matt: the sunrise idea might be out due to visibility requirements.
Jake Anderson
the other groups doing it don't seem to have too much difficulty.
Madox
Max Nippard
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Ada Lim
On Feb 28, 1:41 pm, Madox <madox....@gmail.com> wrote:
> Ada - Can you check up the rules on autonomous guidance? I vaguely recall
> something about that being prohibited as it fell into 'guided missile'
> territory. At least in the US...
into manned and unmanned; unmanned into rockets, balloons, tethered,
and other; and other into commercial and non-commercial.
> Oh wait, I'm a moron, just read the rest of your post ;) 400 ft eh?
> Again, can we chase it in a plane you're flying?
etc); the autonomous device will need some remote control facilities
("avoid that 380"), and you can't see to 100000ft from 10000,
especially not that small a device.
so if you want to launch payload which flies, you'll need to get it
under 100gms.
it shouldn't be too bad; I just asked wolfram alpha and I don't
think that it'll be fast enough to run into any of the special high
altitude conditions (see "coffin corner").
Matthew Chapman
NAIPS is what I usually use for flight planning, possibly that's what
you're thinking of? NAIPS does have wind and temperature data up to
FL445 (i.e. 44,500ft) but it doesn't provide pressure/density and it's
a bit clunky to use for this purpose, since it's all based around
planning a specific flight from A to B in the next little while.
Ideally I'd something in the 100,000ft-150,000ft range, but certainly
50,000ft+. I'm after something like:
Oh wait, it looks like I can plug in Australian station numbers to
that script. Score!!
Apparently the NAIPS data is calculated from 'GRIB upper winds data'
so I might look into that as well.
Re launching before sunrise, yeah there may be visibility issues.
Once the balloon reaches controlled airspace, visibility is kind of
moot, but in the low level portions it may need to be visible to NVFR
traffic. I don't know if there's specific exceptions and procedures
for weather balloons, though, someone who has done launches before may
be more familiar with the process. We might as well just launch at
sunrise, though.
Matt
Jake Anderson
> Re launching before sunrise, yeah there may be visibility issues.
> Once the balloon reaches controlled airspace, visibility is kind of
> moot, but in the low level portions it may need to be visible to NVFR
> traffic. I don't know if there's specific exceptions and procedures
> for weather balloons, though, someone who has done launches before may
> be more familiar with the process. We might as well just launch at
> sunrise, though.
>
> Matt
>
less wind.
Luke Weston
I love the idea of launching an autonomous glider as a payload. I've seen it done before, and it'd be really cool to do it ourselves.-Nick
On Sat, Feb 25, 2012 at 7:08 PM, Matthew Chapman <eno...@gmail.com> wrote:
2012/2/25 Jake Anderson <groo...@gmail.com>:
> thin weldable plastic methinks
I've been doing a bit of reading and it seems the plastic of choice in
the scientific community is polyethylene film, probably because of how
widely available it is.
ISAS in Japan achieved 53km (~174,000ft) in 2002 using a balloon made
of 3.4um thick polyethylene film. Their balloon volume was 60,000
m^3, which is an equivalent spherical diameter of about 48m - though
of course these balloons are rarely spherical because it's too hard to
join the film in that shape - and carried a payload of 5kg.
Of course I'm not suggesting targetting 174 Kft or a 50m balloon
anytime soon, let's aim for the amateur record first ;) But it shows
what's theoretically possible.
(Just to put their achievement in perspective, the air density at
174Kft in the standard atmosphere is 0.0007 kg/m^3, which is >4 times
more rarefied than the 0.003 kg/m^3 at 137Kft.)
M
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Matthew Chapman
If we have a payload of say 500 grams, that should be enough to do pretty much everything we want to do including steered ascent if we are lucky.
I think steered ascent is basically impossible - the wind at high levels of the troposphere is ferocious (often 50knots+ around 40,000ft), and you have a 10m balloon exposed to it. We're going wherever the wind is going. [*] On the other hand, control on the way down may be possible, since we can have a much more aerodynamic surface and have potential energy to our advantage.
I'm increasingly loving the glider idea, especially if it's designed so it can get back to base in typical winds. You can measure the wind on the way up (e.g. from GPS-measured drift), and then do some pretty interesting glide path optimisation on the way down.
how big a balloon would we need to loft that to say 145kft 100kft and say 50kft (in a zero pressure balloon)?
(i suggest we start small and try to make sure we can get the darn thing back ;->)
I'm on the case, I'm going to post some data shortly :)
Matt
[*] Just to put that in perspective, the force required to keep the balloon from deviating in 50kt wind is approximately 30kN - that's roughly the thrust produced by *both* engines on a small business jet. :)
Matthew Chapman
* Payload: 200g vs 500g
* Gas: H2 vs He
* Material: Latex (elastic) vs 3.5um LLDPE (zero-pressure balloon)
* Two different parameters for balloon breakage - the real value will hopefully be somewhere between the two
I've included some tables of results for different altitudes and balloon sizes below.
Here my thoughts on what I draw from this:
Payload
Increasing the payload from 200g to 500g generally increases the required balloon diameter (at burst) by 3ft @ 100k, 5ft @ 137k, and 4-5ft @ 150k - or for a fixed balloon size reduces the ceiling by 13k @ 100k, 4k @ 137k, 1k @ 150k.
If we're going for a record with an off-the-shelf balloon the 4kft difference at 137kft is likely to be important, but the higher the altitude, the less it matters (because you need a bigger and heavier balloon anyway).
We could always do a test flight with lots of instruments and cameras, and a record flight slimmed down to just GPS+comms gear (possibly a home made beacon on a ham band).
Gas
Again this makes a difference of about 4kft at 137kft when using a rubber balloon (and about 2kft difference with LLDPE). The effect increases with altitude though, so H2 is definitely preferable for high altitude flights. While we'd need to be a bit careful about rubber balloons and static, I don't think it's a major safety risk even if it ignites, since the mixing rate with oxygen is limited.
Material
I think at the sorts of altitudes we're considering, rubber is still advantageous, if we can get balloons big enough. Looking at the H2/500g/150kft case, we see a 59ft latex balloon competing with a 48ft LLDPE balloon - but the latex balloon will only be perhaps 12ft when unstretched, and is less likely to tear on the ground.
Also, getting LLDPE film that is 3.5um thin but doesn't tear or leak hydrogen may be quite difficult, the 3.4um film used by the Japanese folks for their record-breaking balloon was custom made for the purpose. Out of interest I ran the numbers for off-the-shelf 12.5um LDPE (cling wrap) and got balloon diameters in excess of 40m/130ft...!
I guess, as you said, one advantage of a zero pressure balloon is that it can ascend faster since it contains more gas, and so should travel less distance in the wind. However, the amount of gas you have to put in is proportional to the cube of the diameter, while the ascent rate is only proportional to the diameter, so I'm really not sure if this is worth it...
Of course there comes a point at which you can't get a latex balloon big enough...
Data
Required balloon size (diameter at burst, ft)
---------------------------------------------
50k 100k 137k 150k ft
Optimistic latex model:
H2/200g 5 12 33 55
He/200g 5 12 38 68
H2/500g 6 15 38 59
He/500g 7 16 42 71
More pessimistic latex model:
H2/200g 5 12 34 58
He/200g 5 13 40 79
H2/500g 6 15 39 62
He/500g 7 16 45 82
3.5um LLDPE:
H2/200g 5 11 28 43
He/200g 5 12 30 46
H2/500g 6 15 33 48
He/500g 7 15 35 51
Ceiling (kft) with given balloon diameter
-----------------------------------------
20ft 30ft 40ft 50ft 60ft
Optimistic latex model:
H2/200g 121 134 142 147 152
He/200g 119 131 138 143 147
H2/500g 113 129 139 145 150
He/500g 111 126 135 141 146
More pessimistic latex model:
H2/200g 121 133 141 146 150
He/200g 118 129 136 141 145
H2/500g 113 128 138 144 149
He/500g 111 125 134 139 144
3.5um LLDPE:
H2/200g 125 139 147 154 159
He/200g 123 137 145 152 157
H2/500g 116 133 144 151 157
He/500g 114 131 142 149 155
Luke Weston
Matthew Chapman
There's some good comments by user David on this post:
http://diydrones.com/profiles/blog/show?id=705844%3ABlogPost%3A777259&commentId=705844%3AComment%3A783296&xg_source=activity
And here's a video of someone igniting an H2 balloon:
http://www.youtube.com/watch?v=cQvpK9cl0No
Matt
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Jake Anderson
On Tue, Feb 28, 2012 at 11:06 AM, Jake Anderson <groo...@gmail.com> wrote:
If we have a payload of say 500 grams, that should be enough to do pretty much everything we want to do including steered ascent if we are lucky.
I think steered ascent is basically impossible - the wind at high levels of the troposphere is ferocious (often 50knots+ around 40,000ft), and you have a 10m balloon exposed to it. We're going wherever the wind is going. [*] On the other hand, control on the way down may be possible, since we can have a much more aerodynamic surface and have potential energy to our advantage.
I'm increasingly loving the glider idea, especially if it's designed so it can get back to base in typical winds. You can measure the wind on the way up (e.g. from GPS-measured drift), and then do some pretty interesting glide path optimisation on the way down.
that will be less effected by the wind on the way down.
how big a balloon would we need to loft that to say 145kft 100kft and say 50kft (in a zero pressure balloon)?
(i suggest we start small and try to make sure we can get the darn thing back ;->)
I'm on the case, I'm going to post some data shortly :)
Matt
[*] Just to put that in perspective, the force required to keep the balloon from deviating in 50kt wind is approximately 30kN - that's roughly the thrust produced by *both* engines on a small business jet. :)
Ada Lim
On Mar 1, 9:47 am, Jake Anderson <groov...@gmail.com> wrote:
> Think a yacht tacking against the breeze not a rocket flying into a
> headwind.
Max Nippard
Or some wheels on the ground.
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Jake Anderson
On Thursday, March 1, 2012, Ada Lim wrote:
On Mar 1, 9:47 am, Jake Anderson <groov...@gmail.com> wrote:
> Think a yacht tacking against the breeze not a rocket flying into a
> headwind.
You need two fluids to tack.
Or some wheels on the ground.A glider can fly into a head wind as long as it isn't to draggy. A clean shape with smallish wings. Many high speed rc planes would work fine. Unless we go nuts and try doing a folding wing that pops out for the final descent. :-)
Either way having a velocity close to 0 for that whole ground impact phase seems like a good idea ;->
Mark Jessop
We've been doing high-altitude balloon launches out of Adelaide for a
while now, and have got the launch and recovery systems working pretty
smoothly.
First off: Contact CASA and start organising permission to launch
*now*. It takes months. You'll be wanting permission to launch
'medium' balloons, which can have up to a 4kg payload.
Without this permission, you'll be limited to launching balloons with
a max 50g payload. This is enough for a GPS unit and transmitter (i.e.
something like my MicroNut PCBs), but not much else.
Second: Start running launch predictions: http://projecthorus.org/predict/
We've found this prediction software (developed by some students at
Cambridge) to be progressively more accurate in the days leading up to
a launch, to the point where if the balloon burst happens when
expected, the actual landing can be within 10km of the predicted
landing.
The same guys from cambridge (who have been doing high-altitude
balloon launches for a *long* time), also wrote a burst calculator:
http://www.cusf.co.uk/calc/
This includes parameters for the majority of the high altitude
balloons commercially available. Project Horus mainly uses 100g,200g,
600g, 1000g 1600g and 2000g Hwoyees, depending on payload weight.
I don't know what the prevailing high altitude winds are like around
Sydney, but it's quite possible you're going to have to launch from
further inland to avoid having your payload land in the ocean.
Third: Dropping a UAV glider from a balloon would be awesome, but CASA
won't like it. You might be able to get away with it further inland,
well away from any flight paths. I'd read over the model aircraft and
UAV legislation very very carefully to be sure you're not breaching
any laws with it. Other option with that is to launch at Woomera.
A few other points:
- Make your first launch be a GPS unit + microcontroller + transmitter
only. Learn how to track and get your balloons back before flying
anything expensive.
- Use a uBlox GPS unit, or something else that has been confirmed to
work >18km altitude. We haven't had any trouble with these losing lock
after landing, even with the payload landing upside down.
- We use Radiometrix NTX2-434.650-HP modules, driving them with a
small voltage shift (not 3.3v TTL - see http://rfhead.net/?p=36 ).
This gives us 425Hz shift FSK (RTTY) output, which we usually run at
300 baud. With a amateur radio receiver on the ground, we can get a
reliable signal hundreds of km away. Said receiver needs to support
receiving sideband (SSB/USB/LSB) on the transmit frequency. See
http://rfhead.net/Project_Horus_Tux_in_Space.pdf for a bit more info.
- Contact local amateur radio operators! We had a floater launch last
year which landed off the coast of Wollongong, and we had an amateur
radio operator in Sydney track it until landing, so there's certainly
amateur radio operators around who know about, and know how to track
these high altitude balloons.
- Don't rely on any phone network. GSM modules and the like usually
stop working above a few km. Also if you land in an area with no
signal then you won't get any data!
- For the best chance of getting your payload back, use a transmitter
which broadcasts data continuously, and track & chase the balloon
throughout the entire flight. You really want to be as close as
possible to the landing site when it comes down, so you can get the
last data points and know the rough area where it lands.
If you have any questions, i'm usually hanging out on Freenode in
#highaltitude and #hackerspace-adelaide with the nickname Darkside.
Cheers,
Mark Jessop
Jason Ball
(now VK2VJB... no more VK2FLNX for me ;)
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Rich Atkinson
Nick Johnson
David Lyon
Fibreglass pcb material is rather durable. Maybe good enough for
something small.
Other benefit is that is entirely constructable at the hackerspace
with existing tools and a few parts.
>>> vk2...@google.com <vk2...@google.com>
>>> callsign: vk2vjb
>>>
>>>
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>
Ada Lim
On Mar 1, 8:21 pm, Rich Atkinson <atkins...@gmail.com> wrote:
> The very concept of making something and sending it to a place we can
> barely imagine going to ourselves is spine tingling!
>
> I've been reading this [1] blog about a project to drop a 550g 'return to
> launch' UAV glider from a weather balloon at 120,000ft. He has some
> interesting ideas about the airframe [2].
approvals required for anything!
Also something like that might be a good way to start on the project,
if we can get GPS+beacon+airframe+brain under 50gm.
Max Nippard
On Thursday, March 1, 2012, Ada Lim wrote:
Michael Molloy
Ada Lim
On Mar 2, 10:01 am, Michael Molloy <iphone.mi...@gmail.com> wrote:
> The lightest glider I have is 112grams, i could get about 20 grams lighter
> but need the weight for C of G balance......
http://www.hobbyking.com/hobbyking/store/__12930__Micro_J3_Indoor_Profile_ARF_.html
but with no motor.
how much weight can you get a navigation payload in? 15gm?
the design:
- large amounts of dihedral for static roll stability
- fixed elevator
- all flying vertical fin for direction control
- CoG toward the nose for stability and spin resistance
and maybe tethered balloon launching to start experimenting.
lifting capacity of helium - 1.1g/litre (hydrogen 1.2g/litre)
so you need 40-45L of balloons (about 50-60cm diameter) to lift that,
tethered on a string, with a release mechanism. a tethered balloon
may be flown under 400ft.
who's up?
Michael Molloy
http://hackerspace.pbworks.com/w/page/51347216/High%20Altitude%20Balloon
Please check it out and add lots more....
Mick
David Lyon
some type of industrial foam.
$10 x 10 members is $100. But I reckon a piece of the source
material would cost $5 and about 20 could be cut for $20 maybe.
ok - they wont be painted nicely so the visual effect will be different.
Max Nippard
The cub is designed to fly with low power so it produces heaps of lift at low airspeed but as a glider even with full down elevator it won't make much distance over ground into the wind. I was thinking of something like slope soarers (gliders built for speed, not maximum lift) or a tiny version of the funjet. At 50g scale it might need to look like a F-105 or tiny space shuttle/lifting body reentry vehicle. (or lawn dart) :-)
Ada Lim
On Mar 2, 11:51 am, Max Nippard <mnipp...@gmail.com> wrote:
> For such light airframes you will need a lot less drag to penetrate into
> the wind.
>
> The cub is designed to fly with low power so it produces heaps of lift at
> low airspeed but as a glider even with full down elevator it won't make
> much distance over ground into the wind. I was thinking of something like
> slope soarers (gliders built for speed, not maximum lift) or a tiny version
> of the funjet. At 50g scale it might need to look like a F-105 or tiny
> space shuttle/lifting body reentry vehicle. (or lawn dart) :-)
do you need to penetrate the wind?
I was deliberately thinking about a draggy design because having too
high a terminal velocity may be bad in the upper reaches of the
atmosphere.
does anyone have an idea of how much an electronics guidance package
would weigh? this could be a 25gm microglider design competition.
david: the foam is usually depron or similar. you can buy it
reasonably easily (I found a source on the northern beaches). Can be
reinforced with CF rod.
Tim
Ada Lim
On Mar 2, 12:44 pm, Tim <cool...@gmail.com> wrote:
> roll anyway, and if you knew the general direction the balloon would
> travel, you wouldn't need a GPS, just a magnetometer, and program it to try
> to keep the nose heading up wind.
plan was to calculate ground direction using the GPS track over the
last 10 seconds and turn to make the GPS track point toward the home
location.
> I don't know exact numbers but all the autopilots I have seen are full of
> silly things like voltage regulators and PCBs, and feel like they weigh
> more than the few grams you'll have to spare...
>
> A magnetometer on a breakout board soldered to an attiny soldered to a 2g
> servo all running from a 500mah single cell should come in at less than 10g
> though? You could afford to put a camera on the front then!
500mah is bucketloads. I was thinking 140mah single cell.
this may be an opportunity to use those msp430s madox is so fond of;
16 bits will make the maths easier, and the micropower helps.
fascinating paper from 15 years ago:
http://www.fas.org/irp/agency/dod/jason/ssp.pdf
Max Nippard
If you can't travel upwind then you would need a target landing zone well down wind from the launch site. That makes ground logistics tricky.
Nick Johnson
Oh yes, the 105 is not so sleek :-)
If you can't travel upwind then you would need a target landing zone well down wind from the launch site. That makes ground logistics tricky.
Max Nippard
David Lyon
Its a question of how fast you want the descent to be.
I still think a pcb frame (embeded circuitry) combined with
foam-surrounds might be cheap and strong.
A big lipoly battery like seen on Talsits beast could aid controllability.
Make toy space-shuttles.. There.. Design is somewhat done and at least
people will recognise the idea.
Michael Molloy
Mick
David Lyon
Most fossil fuels will freeze too at those temperatures.
Andrew
Madox
2)Most = Diesel? Petroleum has a much lower freezing point... that is the more common fossil fuel we commoners use right? [...can't...afford...a...new diesel car...]
On Friday, 2 March 2012 11:08:56 UTC+2, David Lyon wrote:
Most batteries won't like that cold.Most fossil fuels will freeze too at those temperatures.
On 3/2/12, Michael Molloy <> wrote:
> LIPO and cold is bad.... The foam will help but remember the altitude we
> are looking at is very low pressure and very cold more than -50c
>
> Mick
>
> On Friday, March 2, 2012, David Lyon <>
David Lyon
Looked down, saw how cold it was, developed no desire to stop and
find out.
Stick me in a warm country and let me get malaria. Feel free to
check out those freezing places/conditions.
Madox
- Mean temperature: +0.2°C
- Annual rainfall: 535 mm
- Snow stays on the ground 183 days / year.
- Coldest recorded temperature: -45.3°C
David Lyon
how frustrating cold temperatures are.
Anyway, its just worth checking if all the electronics will run properly at those
temperatures. Do some testing in with liquid Nitrogen - perhaps.
James Deucker
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David Lyon
a mylar balloon.
Maybe get lift and store fuel at the same time. Unlike fossil fuels
I don't think anyone has ever been able to freeze hydrogen.
- http://madlabs.info/h2fcrp/h2fcrp_power.shtml
Julian Sortland
in a flask in a beaker which acted as a water bath.
When someone recent yl wanted them to ban helium balloons for
advertising / mass releases at the footbrawl, someone from the
industry came on and claimed that latex freezes solid at altitude, but
that the growing pressure difference then causes the to explode into
powder, so that there is not a pollution issue.
This is pretty cool too: http://www.theregister.co.uk/science/paris/
Julian, VK2YJS.
> --