DIY foilballoon

[HerrCules]

Hey,

I wish you all a happy new year! I'm new and hopefully right here :)

We are two students and want to build a balloon, that flies as long as possible and is controllable in altitude. There is already a long discussion in the arduino forum, therefore I will not explain anything here: https://forum.arduino.cc/t/altitude-controlling-weather-balloon/1418646.

Initially, we wanted to use a normal latex weather balloon and control its height by venting helium or dropping ballast (ValBal). But we would get big problems with UV and in our very small scale (we want to be in the 200 g range) we couldn't carry enough ballast to compensate the density differences between day and night more than a few single times.

So, it would be ideal to use a foil balloon with ballonet, like Zeppelins or the BalMan do.

But we can't find (affordable) foil balloons for our size (we need more than the usual 5–20 g payload). But I've seen, that it's pretty easy to ironing the foil together. Is there a way to buy the normal foil and build a balloon (with inner ballonet) out of it?

Thank you all in advance!

[Mika Köching]

Hi!

I have tried making balloons from PE foil with varying success. It's very hard.

Using balloon mylar foil might work better but as you have noticed it's very hard to get. Maybe you could find some alibaba but I don't know.

PE foil is what I would start with. I used 7µm foil which is super thin and probably lets all the Helium through the foil over the course of a few days though.

[gprokop65]

Hi,

Look at this:

https://tt7hab.blogspot.com/2017/04/the-superpressure-balloons.html?m=1

You need a thin pe-evoh foil, normaly use in food industry

Jens

Von meinem/meiner Galaxy gesendet

-------- Ursprüngliche Nachricht --------

Von: Mika Köching <mika.k...@gmail.com>

Datum: 01.01.26 18:33 (GMT+01:00)

An: UKHAS <uk...@googlegroups.com>

Betreff: [UKHAS] Re: DIY foilballoon

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[Steve]

Few comments:

Looking at the forum.arduino.cc post I would ditch the helium cylinder idea - the amount gas will be minuscule even at 180 bar.   The Alibaba picture says the thread is 5/8in so by eye I'd say the internal volume of the cylinder  would be about 100cc - which is consistent with 2.5g (0.625 mol) of Helium at 180 bar - so maybe 18l of helium at STP = 0.018cu m  or the equivalent of about 18g of lift.  Considerably less than the gas cylinder weight I would imagine. 

You might want to consider Chloroprene balloons as an alternative to latex weather balloons - Chloroprene is much better at handling UV and ozone - medium sized chloraprene balloons (up to 600g) are readily available.

Food packaging foil is probably you best bet for making foil balloons - like multi layer: PA or PET on one side - PE on the other for heat sealing - with an EVOH layer between for gas seal - typically comes in 1m widths.  This is what has been used to make amateur balloons in the past.  

    Steve

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[Steve]

Reading further through the forum.arduino.cc post I noticed a few more wacky ideas (its a long discussion).

There are a few ways to control altitude - but basically the altitude of a floating balloon is set by the density of the balloon/payload system matching that of the local atmosphere - density =  mass of (balloon+gas+payload) / volume of the balloon.  So in order to go up/down you either need to change the volume of the balloon - or the mass of the system (or both).  Decrease the density (increase volume and/or decrease mass) of your balloon-payload system and it will rise - increase density (decrease volume and/or increase mass) and it will descend.

Ballonets are one way to achieve this - they can either be internal to the balloon or external (see earthbreeze: https://www.qsl.net/nss/earthbreeze.html)  The onboard compressors/ turbo pumps needed tend to be the engineering challenge and are difficult at small scale.

One area that doesn't seem to have been explored much is using the phase change of liquid<->gas to get a noticeable change in volume - perhaps by heating a refrigerant gas like R134A.

    Steve

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[HerrCules]

Where did you find chloroprene balloons? I couldn't find anything useful.

[HerrCules]

Like posted in Arduino, we plan to use LoRaWAN via Lacuna Space to communicate with the balloon. Has somebody experience with that? And where do I get a 8x8cm right circular polarized antenna? Seems, that many people make them their self or order a PCB, how does that work?

Thanks!

HerrCules schrieb am Donnerstag, 1. Januar 2026 um 14:16:41 UTC+1:

[Mark Jessop]

What band are you uplinking to the Lacuna Space satellites on? 

Depending on the band you may be better off with a patch antenna of some kind (e.g. a PCB patch) pointing upwards.

73

Mark VK5QI

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[Steve]

The main ones are Pioneer Cloudbusters - as used by the cluster ballooning guys (who trust their lives to them).  They do seem much less available (and more expensive) than they used to be.

Sold under the brand name ToyTex.  Physically identical (and the same mold marks and packaging)  to ToTex (Japan) balloons - so that's who I expect manufactures them.

The 4ft size is around 300g, and the 8ft around 600g (there is a 5.5ft too) - generally they don't perform (burst altitude) anywhere near the same sized latex balloon. 

    Steve

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[Steve]

Should have said there is a variety of colours - personally I'd go for white (as I'd expect less heating).

    Steve

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[HerrCules]

The Lacuna satellites use also 868 MHz, this board is compatible:  iM891A-XL. Lacuna says that we need an 8×8cm right-hand circular polarized antenna, that should be used facing upwards (obviously). Here are a few informations: Lacuna, especially on page 9.

[Dave, G1OGY]

Here is one idea `off the shelf'`

Circular Polarisation Right Hand Circular Patch Antenna, 868MHz,
2.17dBi Gain - Taoglas | CPC
<https://share.google/LOd7OdFiGrg2Jrb65>

Note the data sheet suggests a 70mm square ground plane.

It might be more instructive of Lacuna to quote antenna gain
requirements or TX EIRP than antenna physical size.

Dave, G1OGY

[Mark Jessop]

Be careful here - that slide mentions 'continental switching' - this is because the ISM bands are not consistent worldwide. If you intend to fly outside of the EU you will need to do geofencing and work out what country you are over and pick the appropriate band. There also may not be an appropriate band depending on the countryl..

73

Mark VK5QI

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[Nick McCloud]

On Monday, 5 January 2026 at 23:14:29 UTC HerrCules wrote:

we plan to use LoRaWAN via Lacuna Space to communicate with the balloon. Has somebody experience with that? And where do I get a 8x8cm right circular polarized antenna? Seems, that many people make them their self or order a PCB, how does that work?

Leaving aside that Lacuna isn't an open access constellation, or that it uses LR-FHSS for uplinks, there's the no small issue of ensuring your balloon is under the receiving footprint of a satellite at the right time for transmission - as they are not geostationary.

The Lacuna devices I have weigh 200g+ without batteries and the built-in antenna needs a clear view of the sky - I've no idea what putting a parachute & a metallised balloon in the way will do but suspect it won't help at all. You can't use an ordinary patch antenna.

It may help you to do a bit more research before settling on a solution. 

If you do go with LoRaWAN you will need access to a bunch of gateways and there are limits in place on how many uplinks a device can send on some of the community networks.