micro balloon..
Rob, M0DTS
I've usually done radio monitoring of the recent balloons but
thinking
about some really simple tests, they are not very high altitude but
interesting all the same!
Bear in mind i have no experience with balloons...!
Anyone ever tried getting something in the air with a regular 14"
latex
balloon?
I guess the room for expansion would be less for a smaller balloon so
would burst far earlier?
It's very tight on weight for the payload but i'm sure we could make
something ~15grammes for basic tests.....
FM tx should be easy as there are lots of surface mount minature tx
boards about.
Temp sensor should be easy.
Anyone know of a really cheap and small air pressure sensor for
roughly
measuring altitude?
Ideas/comments?
Rob
M0DTS
James Coxon
Yeah its an interesting idea - I've been exploring it with foil
balloons rather than latex balloons. You wouldn't get very high with
those balloons as you say because they would expand to the point of
burst very quickly but it would certainly be possible.
Initially my question would be why. You might get up to a few
kilometres in altitude but no further - missing out on all the fun of
the stratosphere. Also the payload you developed for this wouldn't
necessarily be ideal for future flights with meteorological balloons,
you'd be sacrificing range etc to get the weight down. That said...
This is where foil party balloons become interesting - they are able
to withstand considerable internal pressure so much that a few of us
think they would super-pressure. With their fixed volume the helium
wouldn't be able to expand further and the pressure would increase,
resulting in the balloons ascension stopping and it floating. This
floating could potentially last for a long time.
This is only a theory but it has been shown to work by some guys in
the states and its something I really want to test out - just need
some helium - it might be a good chance to use 868Mhz rather than 434.
I'm working on a miniature payload, i feel that getting GPS onboard is
important as positional data is pretty key to any flight. I was going
to do a test launch however I had to cancel it as the helium party
balloons I got from Clintons didn't provide enough lift so its still a
work in progress.
I'd see 'micro balloons' (like the name) as actually a whole different
form of amateur balloons - the requirements are considerably different
and perhaps more challenging - in some ways its a completely new
field...
James
M6JCX
http://www.pegasushabproject.org.uk
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Rob, M0DTS
As to the reason why, this is mereley a 'can it be done' experiment,
but it could be used to check out for any temperature inversions in
the 1st km or two above us when there is high pressure around.
I like the foil balloon idea, you could get a variety of that type of
balloon and inflate until they burst to get some figures..
I agree the gps is quite essential but with a limited amount of lift
this is not going to be possible i doubt without a large cost for a
very small gps module...
I thought that a figure below £10 for the payload could be easily done
and with it not ever getting very far it may be possbile to use a
directional antenna to find it's location without too much travelling.
I've not really done much pic/avr coding to provide the data stream so
it would be a good chance to play with that too!!
Will go away and think some more now..!
Rob
In Snowy Middlesbrough, no work for me today ;-)
Neil Baker
Like you I've also been helping out with radio monitoring and am looking to do a launch myself next year on a limited budget. I've also helped out at a few launches.
I was also considering using a much smaller balloon to reduce the cost of the helium and also to limit the distance the balloon will travel before bursting, hopefully making retrieval easier. Obviously it's not likely to be a near space launch, but for me I need to be fairly confident that I'll get the payload back.
I guess the biggest problem is that with reduced lift, the balloon will take much longer to reach burst point and therefore may still travel a long way away?
Neil
Rob, M0DTS
get enough lift and have enough room for expansion in the balloon,
thats why James' comment about foil balloons it worth looking at.
I have been looking today into payload weight, i had thought it was
possible it is actually going to be very difficult to get below 15g!!
Batteries are the biggest problem, TX module + some telemetry with
temp sensor will draw >20mA so ~100mAh battery is roughly what we
need if we want to find it afterwards!
There's some small ~200mAh nimh? 3.7v batteries in tiny electronic
equipment (like minature mp3 players etc..) we can salvage them from,
they are usually in a silver wrapper.. I think these must be the
lightest i've seen for the mAh.
I must get one of those little digital weighing scales!
The DS18B20 is fun when you know very little about pic and basic
code...ha i will get there i'm sure, the rtty keying was the easy
bit!
Whether i will ever get to test it in the air is another thing but
very intersting experimenting with the ideas.
Rob
On Dec 23, 1:29 pm, Neil Baker <n...@futurity.co.uk> wrote:
> Hi Rob,
>
> Like you I've also been helping out with radio monitoring and am looking to
> do a launch myself next year on a limited budget. I've also helped out at a
> few launches.
>
> I was also considering using a much smaller balloon to reduce the cost of
> the helium and also to limit the distance the balloon will travel before
> bursting, hopefully making retrieval easier. Obviously it's not likely to be
> a near space launch, but for me I need to be fairly confident that I'll get
> the payload back.
>
> I guess the biggest problem is that with reduced lift, the balloon will take
> much longer to reach burst point and therefore may still travel a long way
> away?
>
> Neil
>
Spike
In the past I've used teeny tiny LiPo batteries from
http://www.micronradiocontrol.co.uk/lipo_fullriver.html - may be not
so good at low temperatures.
HTH
Spike
Alexei Karpenko
NiMH doesn't work well at cold temperatures. I think a small li-poly
battery will be much better:
http://www.bsdmicrorc.com/index.php?categoryID=41
Those are usually rated at 10C draw (i.e. you can draw 10 times the
specified capacity), but at temperature that would be reduced. But they
can deliver much more current than you need anyway.
Alexei
Rob, M0DTS
Right so now i know what small LiPo battery looks like! that's the
ones i was talking about with the silver 'wrapper'.
I had assumed they were old and nimh!
Thanks for the links.
Rob
Michael Matthes
I didn't follow the whole conversation, but I will write you some info (I
hope new for you) we worked out this year with the rest of one of our helium
bottles from our balloon launches (www.ballonprojekt.de or
www.balloonproject.eu).
As we plan also to develop an as we call it pico-balloon we did some
measurements.
Balloon 1:
- empty envelope 19g plus fastener (I'm not sure if this word is correct) 5g
- filled with air 55cm diameter: 28g, 65cm diameter 31g
- filled with helium 4.6, 55cm diameter: lift = 90g, after 24h lift = 55g
(diffusion)
Balloon 2:
- empty envelope 58g plus fastener 9g
- filled with air 60cm diameter: 70g, 70cm diameter: 71g, 80cm diameter: 74g
- filled with helium 4.6, 70cm diameter: lift = 212g, after 22h lift = 171g
Greetings and 73s de Mike DL2SEK
-----Ursprüngliche Nachricht-----
Von: uk...@googlegroups.com [mailto:uk...@googlegroups.com] Im Auftrag von
Rob, M0DTS
Gesendet: Dienstag, 28. Dezember 2010 19:38
An: UKHAS
Betreff: Re: micro balloon..
Rob
Solar Balloonman
Although I think a slightly larger balloon, might be better, as it
could take more weight. Think Michael Matthes is going the right way,
maybe just a bit smaller. Say 50cm/20inch diam. Recon it should lift
about 75-80g.
Small bateries can be found. They are used in the 'antweight' class
of robot, (max weight 100g) from Robot Wars. (The fighting still
continues, though not on TV.) In that class the robot MUST fit in a
6inch cube. So the payload size should also be small.
James Coxon
I've been thinking...
http://ukhas.org.uk/projects:picoatlas
Thought I'd construct a super lightweight payload (< 100g) to see if
the micro balloon concept is realistically possible. While the cost of
the components will be relatively high I'm hoping to make a nice
simple payload and document it all in the process - this will
hopefully be useful for both 'standard' payloads and future micro
payloads.
If all goes to plan we'll be testing this out on Monday 17/1/11.
Anyone is welcome to help out with this, will certainly be a chance to
help with the code and also think of some additional cool stuff we can
do with the hardware.
James
Rob, M0DTS
I will be following with interest.
My idea of micro balloon is very much sub picoatlas, here is my lastest
thinking on the idea...
Pic16F628 ucontroller - Code written in picbasic (my c knowledge is near
zero)
DS18B20 temp sensor
Quasar QFM-TX1 tx module - Inverted V wire antenna (some H and V polarity)
Pressure sensor - not yet decided but nothing special as it will not get
that high!
3.7v 90mAh LiPo battery
Packaging
Current weight approx 10g.... Looking good!
Could probably squeeze a GR-10 GPS receiver from sparkfun in there and
smt antenna in there in the future for another 2g or so!
Rob