Launch Announcement - Wed, 25th June - Shrewsbury

[Nick McCloud]

After a two year hiatus, I'm back to launch another balloon at Packwood School just north of Shrewsbury - halfway between Birmingham & Stoke-on-Trent, then west a bit.

LoRa mode 1 on 434.666 (notional, my base station & mobile trackers are reporting ±10kHz), callsign Tenacity.

As it's an old school PITS, it comes with RTTY USB on 434.333, baud 300, callsign Woodi, the school mascot seen on SSDV.

Aiming to launch at 10:30.

We will have a base station on LoRa and the Minibus will have trackers on LoRa and  RTTY but the more the merrier to join us would be appreciated.

The predictions are looking 'challenging' for a minibus full of year 7's for the retrieve, so we may restrict the height or just send me or, very much less likely, scrub . I'll update this thread as things develop, I may be able to do IRC on launch day.

Huge thanks to Steve for getting me sorted with consumables to make this happen - finding the balance between balloon size & helium cost was pivotal to proceeding.

And thanks to Ross, who is so overdue a coffee, for picking up my transmissions from the other side of the River Croal. So helped with testing this morning - your own kit hearing the payload is good, but confidence reaches 110% when someone else is uploading telemetry just fine.

Nick

[Nick McCloud]

Just received permission slip from CAA. Flight time looking like 2h33m from 52.8,-2.9, still aiming to launch at 10:30 with the whole school watching!

There is BakTrak joining in on 434.555 (again, notional, old crystals do seem to drift), Mode 1, just positioning report.

Significant Other, aka ThePayloadRetriever, will take a tracker from home to Peak District where the current predictions are falling, as we are aware the bumpy bits can block signals.

Cheers!

[Nick McCloud]

Many thanks to everyone assisting with tracking and particularly to the lone wolf G6GVI-Z who listened to BakTrak.

We didn't land in a tree. Instead we managed to land right in the middle of the second largest quarry in Europe. Both the minibus and Trubsie_chase were at the back of the quarry and when we got to the edge, picked up the final location plus enough of a picture to see the big rocks.

Daniel, the site supervisor, Tim & Rick were totally awesome in facilitating the pickup, taking me in with a receiver & laptop, providing, hi-viz, hard hat & eye protection, negotiating around monster trucks in what did feel like a large pickup utility vehicle, using a surveyor drone to scout out the area in the waste rock pile and then Daniel going in to retrieve the payload. 

So an excellent end to a multi-month class room project.

[Nick McCloud]

Technical observations:

Filling in a gusty breeze is a challenge - we used all of the 10l / x-small cylinder from BalloonHelium.co.uk and whilst it looked like it might have enough neck lift, it was very hard to tell. I juggled the ascent rate to 4.7m/s to use all He so the published capacity should have been sufficient. However I did a little top up from some left over He from a part used long-term rental. I'll see if I can figure out how much we'd used and review the ascent rate profile / averages against previous much calmer launch conditions.

General technical bit-rot & "upgrades" in the eco-system made for a few challenges:

• The ThePayloadRetriever aka Trubsie_chase was receiving but the Pi wouldn't connect to the iOS hotspot - was working the evening before.
  
• The ThePayloadRetriever's borrowed vehicle, a 1 year old hybrid car, wouldn't start due to a flat battery - but got going in time to be onsite.
  
• School WiFi thwarted me in so many ways I can't begin to list them - so the base station was receiving, but couldn't pass on the results.
  
• It transpired my own receiver, a dual radio Pi, has some issues with the RFM98's in combo with the antenna, to be investigated.
  
• Prior preparation uncovered enough changes to RPi OS that PITS wasn't working as expected. But I had images from prior flights so fell back on using those, to be investigated as I have an original Pi A+ stack plus a Pi Zero stack that can continue to see service.
• Despite using the known good image, the PITS refused to boot at launch site, unlike the 20+ times it had worked in build & testing over the prior week. Popping it in to my portable Pi setup got it back up & working again - I think it may have be an fsck thing.

The original Pi HAB Chase unit developed for the RPF Skycademy was the only one relaying from the minibus but we could see telemetry on Trubsie and, when close enough, my unit.

Upgrades / modifications:

• Moving to FlexTrack with a dedicated no-OS board providing rock-solid no BS location & environment telemetry will eliminate the whole Pi OS / SD Card risks and keep the Pi camera element away from multiple removal of power.
  
• With the range of different mobile operators & industrial SIM deals, moving to mobile internet on base station and trackers will eliminate issues with phone pairing and school firewalls.
  
• General upgrades of the older Pi2's that have served well for base station & receivers but are getting clunky & sluggish.
• A strobe & buzzer would have helped with the final 50m of wandering around.
• Finding / making an app to show both range and bearing from user location to last co-ordinates from payload - the usefulness of most websites & Android apps found in the moment was very poor.
• Get a TTGO watch to implement Dave's "go this way" code - or something similar.
• I'll put in a bid to the Head of Finance for a drone that has a "go to co-ordinates" option. If I strike lucky it might be big, green & Thunderbird 2 shaped with a winch with claw on it ...
  
• Complete the brake overhaul on the MX5 so we don't have to borrow a car ...

I've another school launch in the Netherlands early Sept so time to enact some of the above. I've also some 'spare' Hydrogen & a bit of Helium & some older balloon stock to test new builds with.

I'd forgotten how much fun it all is (!) - and how good it is for the non-sporty, not-cerebral students, ie the geeks, nerds, makers, potential engineers, to get stuck in to something like this. The two challenges to resolve for school is a flight under 2m at burst to remove the requirement for CAA permission, thereby restricting them to particular launch windows which really doesn't work with school calendars and being able to use smaller amounts of Helium to reduce costs - either disposable (not keen, but needs must) or an X-Small that can cover two or more launches. Ideally it should be a kit that doesn't require me to be there as it is rather time consuming to do a full launch - but I can answer questions and improve docs remotely.

[John Laidler]

Nick,

A couple of great reports and you remind me how much things have changed. I powered up my LoRa base station recently and couldn't get it to work, as you say Pi changes were possibly the cause.

It's a bit like IoT, where you helped me enormously get a tracker working a few years ago and it performed very well in flights in Europe. But the IoT has changed so much now I would have to start again although there are boards like the Heltec which have built in GPS and with the right code could be made to work. Something for the future, I'm using one at the moment as a tracker in my campervan. It talks to an iGate in the van which connects to the onboard wifi I've installed.  Portable/mobile wifi is certainly very convenient and with a MiFi device very affordable and you can put it in your pocket when on foot. I use a router now with an external antenna but previously used a MiFi and it was fine.

John

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[Ross G6GVI]

And thanks to you Nick for providing test signals for our LoRa receivers (which haven't had much excercise in the last year).

I was pleased to find that my original Pi2B (G6GVI-L), newer PiZero (G6GVI-Z) and and old TTGO USB (G6GVI-B) were still working well. They were all running from a vertical 12-ele yagi (with masthead preamp) which I'd put up for the day and I swapped one feed from the Zero to the TTGO half-way through, just to compare them: 

https://grafana.v2.sondehub.org/d/HJgOZLq7k/basic?var-Payload=BakTrak&from=2025-06-25T10:05:47.635Z&to=2025-06-25T12:18:38.163Z&orgId=1&timezone=utc&viewPanel=panel-5

I noticed that in the highest part of its trajectory the signal dropped off, as it went up above my antenna's main lobe.

Ross.

[David Brooke]

On Thu, Jun 26, 2025 at 02:29:59AM -0700, Nick McCloud wrote:
> Many thanks to everyone assisting with tracking and particularly to the
> lone wolf G6GVI-Z who listened to BakTrak.

I did try to receive it but was unsuccessful. My second LoRa receiving
setup is not as sensitive as the main one (confirmed by tuning it to the
primary payload, where it received about half as many packets).

> We didn't land in a tree. Instead we managed to land right in the middle of
> the second largest quarry in Europe.

I did wonder how you'd get on with the recovery when I saw where it had
landed so it's good to hear that they were so helpful.

David G6GZH

[Nick McCloud]

BakTrak was built for convenience & weight limit - my original LoRaWAN Pro Mini + RFM98 PCB that could run the LMIC stack before bloatware occurred was used with a Neo6M GNSS of dubious origin using older version of DA's LoRa code and some other bits. Either I got the flight mode wrong or it's a clone. Pigtail antenna with tiny tiny cardboard/tin foil ground plane. So not optimised so much - more about providing a second signal if the main PITS goes offline - the main part of the flight is fun but the trick for a successful retrieve is to be around for the last 500m - you can see on SondeHub the list of listeners disappearing as they lose line of sight. And once it lands, there are two radios, potentially apart, with a fighting chance of getting a signal out.

With a reasonable chunk of polystyrene around it and some gaffer tape, comes in at ~60g about the size of a soda can, so really needs a bit of refining on the weight side of things. Placed half way between main payload & parachute.

[Nick McCloud]

PS, some way have spotted that in the top third of the flight there were receivers on the north coast of France near Calais!