CUSF Launch Announcement

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William Yu

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May 20, 2023, 12:43:53 PM5/20/23
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Hi all,

After many years, CUSF is launching a new HAB! We will be flying from Churchill College at around 2pm BST with an expected westward drift. 600g balloon will hopefully get us to 27km (final weight pending).

Main tracker is a custom Pi Pico board running LoRa Mode 1 on 434.425 Mhz - callsign Longan. 
Backup tracker running Horus Binary 4FSK V2 on 434.600 Mhz - callsign FHS-RS1.

We will of course be tracking ourselves but any help appreciated :)

Many Thanks

Will
Cambridge University Spaceflight

Matt Taylor

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May 20, 2023, 1:14:46 PM5/20/23
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I'm assuming this is flying tomorrow? 😊

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William Yu

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May 20, 2023, 4:22:26 PM5/20/23
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Haha yes, Sunday 21st May! Forgot to include...

Steve

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May 20, 2023, 4:29:38 PM5/20/23
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Great to see CUSF launching again.

    Steve G8KHW

Andrew Mulholland

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May 21, 2023, 8:38:09 AM5/21/23
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Just to confirm, the launch has been delayed now it looks like until 3pm BST, possible 3:30pm. Will send a further update when we are at the launch site making final launch prep.
The students are currently just fixing some last minute technical issues.

Andrew Mulholland

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May 21, 2023, 10:44:29 AM5/21/23
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Filling is now starting, hoping to get it up in the next 15-25 mins.

Steve

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May 21, 2023, 11:01:00 AM5/21/23
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Wow that's an interesting flight path with a local landing.

    Steve G8KHW

John Laidler

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May 21, 2023, 11:20:32 AM5/21/23
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Very slow ascent rate - interesting. :-) 

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M5JFS (John Stringer)

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May 21, 2023, 11:56:46 AM5/21/23
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interesting to watch the progress on sondehub, it's location/altitude hasn't changed for a while (nr Royston) yet packets are apparently still being received? 

Antal Vincz

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May 21, 2023, 12:07:57 PM5/21/23
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Hi,

Is this the MODE 1 parameters?

Error coding 4:5, Bandwidth 20.8kHz,  SF 6, Low data rate optimize off

Thanks

Tony

John Laidler

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May 21, 2023, 12:08:00 PM5/21/23
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The other payload is working: FSH-RS1

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John Laidler

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May 21, 2023, 12:09:19 PM5/21/23
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Correction: FHS-RS1

Andrew Mulholland

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May 21, 2023, 12:31:18 PM5/21/23
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Certainly a whole lot lower ascent rate than had been planned.... The aim had been 3-3.5m/s. Think it's going to be quite a wait till it lands

My hunch is for whatever reason the Longan tracker has lost GPS fix? The trusty radiosonde though still seems happy enough. This is why you never flight with 1 tracker!

Steve

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May 21, 2023, 12:35:42 PM5/21/23
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I had wondered about GPS lock before it lifted off - LONGAN was dithering its position much more than I would have expected.

    Steve G8KHW

John Laidler

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May 21, 2023, 12:46:54 PM5/21/23
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'Tis working now. Must have just had a snooze. Odd. 

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Andrew Mulholland

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May 21, 2023, 12:48:07 PM5/21/23
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Well at least now it looks like it is back. Still looking like it's going to be a night time recovery. My estimates put it coming down 10:30pm

M5JFS (John Stringer)

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May 21, 2023, 12:50:59 PM5/21/23
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odd that there are two very different predicted tracks [for the two payloads] on sondehub.

Steve

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May 21, 2023, 1:00:01 PM5/21/23
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Yeah - you get that - slightly different ascent rates calculated from different data points.

    Steve

Steve

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May 21, 2023, 1:01:46 PM5/21/23
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Looks like it might swing overhead (I'm in Felixstowe) and clear skys  - got my camera batteries on charge.

    Steve G8KHW

Steve

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May 21, 2023, 1:05:07 PM5/21/23
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What balloon is it? - if its large and Hwoyee with a light payload then its likely to float - maybe overnight until sunrise.   Helium/Hydrogen?  

    Steve G8KHW

Andrew Mulholland

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May 21, 2023, 1:22:50 PM5/21/23
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It's a 350g Hwoyee with a 1.13kg payload with helium. So hoping it bursts earlier than it's meant to!

Mike Sharps

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May 21, 2023, 1:30:54 PM5/21/23
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Original post said 600g balloon ?? Did it change 

William Yu

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May 21, 2023, 1:45:46 PM5/21/23
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Yep, switched to 350g because it gave us better predictions - however turns out we severely underfilled ..

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noddym

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May 21, 2023, 2:05:03 PM5/21/23
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With less gas inside, you should get a higher burst altitude, although it might take a while to get there! What descent rate does your parachute give you?

Steve

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May 21, 2023, 4:16:23 PM5/21/23
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Here is a pic of it - brightest thing in the sky - in the right position - no stars out.

    https://drive.google.com/file/d/1_hp497-4592Gs-vzEr2buaggf2JKSzwv/view?usp=share_link

    Steve

Andy Mell

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May 21, 2023, 4:17:13 PM5/21/23
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Where are you tracking it? I can’t seem to find either payload on sondehub. 

Sent from my iPhone

On 21 May 2023, at 17:35, Steve <st...@randomaerospace.com> wrote:



Nigel Worsley

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May 21, 2023, 4:40:09 PM5/21/23
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On Sun, 21 May 2023 at 21:17, Andy Mell <andy...@gmail.com> wrote:
Where are you tracking it? I can’t seem to find either payload on sondehub.

I thought it was just me having that problem!

Nigle M0ZFJ
 

Steve

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May 21, 2023, 4:44:40 PM5/21/23
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Steven Jenkinson

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May 21, 2023, 4:47:17 PM5/21/23
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I bet you weren’t expecting to have to pull an all nighter to see this one safely down! 

Steve

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May 21, 2023, 5:09:39 PM5/21/23
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Looks like a float to me - the question is for how long.

    Steve G8KHW

On 21/05/2023 21:47, Steven Jenkinson wrote:
I bet you weren’t expecting to have to pull an all nighter to see this one safely down! 
On Sun, 21 May 2023 at 21:44, Steve <st...@randomaerospace.com> wrote:
On 21/05/2023 21:39, 'Nigel Worsley' via UKHAS wrote:
On Sun, 21 May 2023 at 21:17, Andy Mell <andy...@gmail.com> wrote:
Where are you tracking it? I can’t seem to find either payload on sondehub.

I thought it was just me having that problem!

Nigle M0ZFJ
 
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noddym

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May 21, 2023, 5:16:59 PM5/21/23
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Hmmm - will latex leak? Or has it reached that balanced state?

Steve

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May 21, 2023, 5:24:06 PM5/21/23
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Its reached a balanced state - the elastic of the envelope in balance with the differential pressure.  Floats are quite common with low ascent rate latex balloons - particularly Hwoyee.  This is a smaller balloon with a heavier payload than we normally get to float - but never the less it seems to have entered one.  Worst case they can go overnight - bursting at dawns light.

    Steve

John Laidler

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May 21, 2023, 5:25:25 PM5/21/23
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I guess not enough gas to inflate the balloon to bursting point. Will the batteries hold out for a circumnavigation? I suspect not but great respect to the CUSF team for the launch. Learning is all about having a go. Frontiers of knowledge and all that stuff.  :-) 

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QBJ30QnOsMnAW6Wf.png

John Laidler

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May 21, 2023, 5:25:55 PM5/21/23
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noddym

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May 21, 2023, 5:27:27 PM5/21/23
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For future reference, we are practicing tethering the balloon and payload on a 35 metre light-weight tether and get the timing to the 7 sec mark at max extension (5 m/s). Add/release gas as required to achieve desired rate. Once achieved, tether can be cut. 

noddym

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May 21, 2023, 5:35:41 PM5/21/23
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Well done guys for getting the launch 👏. It’s a learning experience for us all 🙏

William Yu

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May 21, 2023, 5:35:57 PM5/21/23
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Very tragic - we'll wait out here for half an hour for a miraculous burst before heading back.

Will

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Steve

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May 21, 2023, 5:38:10 PM5/21/23
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Any idea how long the tracker will hold out?

    Steve

Mark Jessop

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May 21, 2023, 5:43:44 PM5/21/23
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The RS41 should last for maybe 20+ hours off fresh Energizer Lithium AAs, though it depends on the transmit update rate and transmit power settings.

A good opportunity for stations to have a go at receiving something other than LoRa ;-)

I'm also surprised there's no other telemetry data coming off the LoRa payload? I thought HAB-Base and co would upload that now?

73
Mark VK5QI

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Mark Jessop

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May 21, 2023, 5:50:43 PM5/21/23
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I've also just adjusted the predictor settings [1] for FHS-RS1 to allow it to run a float prediction, so we can see where it might go.
If it starts descending it'll switch back to a regular prediction of course.

I noticed the expected ascent rate had been set to 1.1m/s, which is certainly in float territory for many balloons!

If you haven't seen these before, you can also view a dashboard showing telemetry from the flight here:

73
Mark VK5QI

noddym

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May 21, 2023, 5:59:16 PM5/21/23
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That prediction puts it up in my neck of the woods (Arley, Cheshire). I’m off tomorrow, so if it comes down I’ll attempt recovery and get it back to you.

Andrew Mulholland

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May 21, 2023, 6:09:21 PM5/21/23
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That’s very useful to know Mark, having never actually needed to drain the batteries on a radiosonde, I wasn’t sure how long it would go. It did have fresh batteries in it, so fingers crossed.

The other tracker (LONGAN) was a custom Pi Pico based tracker. It wasn’t sending anything beyond really GPS data back for this test. It also used x2 AA batteries.

And noddym, would certainly be rather impressive if it makes it up that far and is still transmitting!

The team have given up and are heading back to Cambridge now (and I’m heading back to London). They are keep an eye on it throughout the night and jump to action on the off chance it bursts.

It’s predicted burst height is so close to where it is floating right now, it must be right on the edge of bursting…


Thanks everyone for the help today though, at one point I think I counted 40+ receivers for the radiosonde. It was our first time moving over from RTTY to Horus with the radiosonde, seems we really were behind the times!

We will cross our fingers for a burst before the batteries die.

On 21 May 2023, at 22:59, 'noddym' via UKHAS <uk...@googlegroups.com> wrote:

That prediction puts it up in my neck of the woods (Arley, Cheshire). I’m off tomorrow, so if it comes down I’ll attempt recovery and get it back to you.
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M5JFS (John Stringer)

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May 21, 2023, 6:21:42 PM5/21/23
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This has been fascinating to track online today while following the conversation here. It has prompted me to get something organised so I can receive more than just the regular LoRa weather sondes using a TTGO module. 

Good night all!

noddym

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May 21, 2023, 6:41:14 PM5/21/23
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Mark
I am intrigued… how on earth do you get the predictions to be so accurate?!! The flight path is incredibly precise! I get that you upload the various sig weather and upper wind charts, but then you have to combine that with predicted flight time through the particular levels, so I’m assuming ascent and descent rates are accounted for and included… It’s just brilliant what you guys have done - thank you 🙏 

On Sunday, May 21, 2023 at 10:50:43 PM UTC+1 Mark Jessop wrote:

Mark Jessop

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May 21, 2023, 6:45:41 PM5/21/23
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Short version is - we didn't write the predictor - CUSF did!
We've taken on hosting it and are continuing to maintain it and add features, but the core of it is still the same predictor that's been around for >10 years now.
The code for our fork is here: https://github.com/projecthorus/tawhiri/

It is using the GFS weather model at its core. As for prediction accuracy, this depends on the accuracy of the GFS model, and the accuracy of the other input parameters like ascent rate, burst altitude and descent rate. The predictions shown on the tracker are updated live, using real time parameters from the flight. As Steve mentioned earlier, multiple payloads on the same launch may have different predictions due to slight differences in the calculated ascent or descent rate.

Another question - what are the fields sent in the LoRa telemetry?
$$LONGAN,2990,22:39:39,51.96962,0.98495,16534,0,0.0,-45.0,-51.9,4071,27.7,0.0,0.0,0,0.00000,0.00000,0.00000,0.00000,0.00000,0.00000,0.00000,0.00000,0.00,0.00*CD03

73
Mark VK5QI

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William Yu

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May 21, 2023, 6:52:02 PM5/21/23
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Yeah, the ascent rate was definitely far too low... As Andrew said we are now on our way back to Cambridge. Thank you to all who tracked and for all the advice; we definitely have a lot to debrief and to improve for our next launch. Thank you also to noddym for the kind offer to pick it up if it lands near.

Will

noddym

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May 21, 2023, 6:52:10 PM5/21/23
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Perfect - it works!

Thank you to all who make this easier for the muppets like me out there 👍

M5JFS (John Stringer)

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May 22, 2023, 2:03:48 AM5/22/23
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Just checking in this morning, still floating :-)

float.PNG

Steven Jenkinson

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May 22, 2023, 2:07:26 AM5/22/23
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Just LONGAN transmitting since 6am though. 

Talitha

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May 22, 2023, 2:22:52 AM5/22/23
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Hi, new here. I just wondered if someone could let me know what the aim is with this hobby? Is it to see how far you can get the balloons to travel, and to keep tracking them? Thanks.

noddym

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May 22, 2023, 3:20:51 AM5/22/23
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Hi Talitha
That’s the aim for some (although with a hefty payload, you don’t really want to lose it!), others could be going for altitude, weather data or scientific research, then there are those like me who just want to send a bobblehead and go-pro as high as possible and get the video back! 😂

noddym

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May 22, 2023, 3:23:28 AM5/22/23
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LONGAN still strong, but looks like FHS-RS1 has given up the ghost…

Stuff Account

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May 22, 2023, 3:34:38 AM5/22/23
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Landing prediction looking like ‘you Wensum, you losesum’
😉 

Mark Jessop

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May 22, 2023, 4:01:02 AM5/22/23
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Shame that the RS41 died!
I'd be interested to know what settings were used on it, e.g. transmit power, transmit rate. 
I would have expected more than the ~12 hours of battery life that it achieved.

73
Mark VK5QI

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Steven Jenkinson

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May 22, 2023, 4:02:38 AM5/22/23
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Looks like it may be on the way down now? Might even make landfall

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jacqueline day

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May 22, 2023, 5:29:19 AM5/22/23
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Thanks. I'd be interested in the scientific research if anyone has found anything shareable.




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PE2BZ

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May 22, 2023, 5:33:16 AM5/22/23
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It was transmitting constantly, without pauses. 

I also noticed there was one regular 100 baud 4fsk transmission and one shorter 4fsk transmission which would not decode in either 50 nor 300 baud mode in HorusGui.

I am also curious about the settings used for the RS41 

Steve

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May 22, 2023, 6:03:58 AM5/22/23
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Sometimes serious stuff too - some aircore flights I helped predict, launch, track and recover a few years back:

    https://acp.copernicus.org/articles/20/9771/2020/

    Steve G8KHW

Ross G6GVI

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May 22, 2023, 6:39:00 AM5/22/23
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The FSK transmitter stopped abruptly at 06:03 BST:
snr.png
One moment it was loud and clear, but the next instant it was "gorn".

The LoRa signal has been much weaker - last night I couldn't decode it at all (just 250 CRC errors), so this morning I put up my 12-ele and have still only mangaged to acquire a few dozen packets (from here in Bolton).

Mark Jessop

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May 22, 2023, 6:51:21 AM5/22/23
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The 4FSK transmitter (a reflashed Vaisala RS41) stopped because the batteries died. Unfortunately in its stock configuration, the RS41 will shut down when the battery voltage falls below about 1.7V (this is due to some peculiarities of the power input circuitry, if bypassed it'll run down to 0.8V or so).

You can see the battery voltage vs time in the plot at the bottom left of this dashboard (scroll down): https://grafana.v2.sondehub.org/d/HJgOZLq7k/basic?var-Payload=FHS-RS1&from=1684681753614&to=1684732297614&orgId=1

73
Mark VK5QI

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noddym

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May 22, 2023, 7:38:40 AM5/22/23
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Could be time to get the dinghy out! 

Steve

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May 22, 2023, 8:13:43 AM5/22/23
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Looks like it might land (float!) just off Great Yarmouth. 

One time we got their seal watch guys to go and recover a payload,  another the team somehow got the Gorleston-On-Sea RNLI out for a training exercise.

    Steve G8KHWv

William Yu

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May 22, 2023, 8:19:55 AM5/22/23
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I've gone from despair at not being able to recover the payload, to being pleasantly surprised that my tracker has survived this long! Will be very happy if it ends up landing near (preferably on) the coast...

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Steve

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May 22, 2023, 8:29:20 AM5/22/23
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I'm not sure how accurate the landing spot prediction is - the software will probably assume an exponential speed decrease with altitude (typical for burst/parachute) - whereas the actual descent rate is not far from linear (typical for a leak).

I think you may see the landing spot get closer to the current position as the flight progresses.

    Steve

jacqueline day

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May 22, 2023, 9:09:10 AM5/22/23
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Thanks for sharing that, Steve. Complicated data!




Mark Goergen

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May 22, 2023, 9:19:40 AM5/22/23
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Our first flight was for my daughter's science fair. It compared the speed of sound with temperature. We do regular launches with middle and high schools in conjunction with science curricula regarding the atmosphere and physics. These launches give each student a role such as Horus radio operator, Spot Trace operator, flight tracking, payload release, etc.  Many of them go through a NASA-like series of "xxx-system go for launch" responses for the launch director. A local meteorologist and I participate in a class before launch and another after getting the flight results. We are working with a company to test the viability of using balloons with smaller sensors for space surveillance (tracking satellites). 


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William Yu

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May 22, 2023, 9:45:38 AM5/22/23
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Hi all,

It seems like after a heroic, 23 hour flight, Longan has unfortunately finally landed in the sea. This is most likely unrecoverable save for it potentially washing up and being found on the beach. Thank you to all who helped with tracking - it's massively appreciated. A lot of important lessons (re)learnt for CUSF, which we will definitely use as we put up more launches in the next couple years. 
If anyone is interested in the payload design, launch etc I can drop some pictures and video in this chain

Will

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jacqueline day

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May 22, 2023, 9:51:07 AM5/22/23
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The children must love your involvement. Very curious how you could track satellites when presumably they are much further up than a balloon could ever go? And how would you keep up with them? 




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Steven Jenkinson

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May 22, 2023, 11:13:16 AM5/22/23
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RIP Longan. In good company though, as I reckon there's a few Skycademy casualties from years back that landed around that same spot of water.
Thanks for reigniting some interest, Always worth dropping pics and videos here, you never know what pearls of wisdom you'll uncover! I'm sure someone will be along soon to re-emphasise the need for a couple of extra 'Stirks' of gas upon filling ;)

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Andrew Mulholland

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May 22, 2023, 11:19:32 AM5/22/23
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2 quick photos I snapped from the launch on Churchill College Lawn.

photo_2023-05-22_15-58-21.jpg
photo_2023-05-22_16-17-11.jpg

John Laidler

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May 22, 2023, 12:11:35 PM5/22/23
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Many thanks for the reports and the photos. I guess not being able to recover it means you may never find out what was the issue with the LoRa payload and why it stopped transmitting a position for a while. It might have been interference and the GPS module could not get a lock but that doesn't explain why it stopped and then started again.

May I ask how you measured the free-lift or neck pull? I used a plastic milk bottle filled with water with a mass equal to the payload plus the free-lift. Simple but effective. 

You must try a camera next time and gets some SSDV images in flight beamed back.

John
M0WIV 

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Steve

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May 22, 2023, 1:29:56 PM5/22/23
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Thanks for the photos - Churchill launches are a trip down memory lane for me.

Measuring lift in the middle of a windy field can be difficult. Air moving over the top of the balloon (relative to that close to the ground) seems to create a bit of extra lift.

Once upon a time CUSF had a snazzy gas flow meter? (for measuring the amount of gas dispensed).

    Steve G8KHW

On 22/05/2023 16:19, Andrew Mulholland wrote:
2 quick photos I snapped from the launch on Churchill College Lawn.



Mark Goergen

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May 22, 2023, 4:00:02 PM5/22/23
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Great question! We don't actually track the satellites. We just identify that there is a streak at a certain elevation and azimuth from the balloon's location. That data is then matched up to the existing catalog. If there is a match, it verifies thay the satellite is still in the previously identified orbit. Of course, this requires pointing knowledge and payload stabilization with a small gyroscope. Luckily, the sensors are small. Right now, we are simply verifying the quality of streaks and points with different sensors.

jacqueline day

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May 22, 2023, 5:03:28 PM5/22/23
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That's really interesting. But how do you azimuth a streak of light?




Mark Goergen

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May 22, 2023, 6:52:07 PM5/22/23
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You need to have an inertial measurement unit (IMU) so you know where the main body is pointing. Then you add the az/el of the camera from the main body. This will not be a pico:)


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Andrew Mulholland

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May 23, 2023, 2:40:49 PM5/23/23
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Had meant to follow up on the LoRa fields question earlier. The firmware being used is this one (mainly written by William) - https://github.com/westminster-school-balloons/Pico-flight-tracker
It had been built up over the past few years and included support for some rather accurate pollution sensors (and a BME sensor). There was even a previous experiment for measuring solar energy at different altitudes.
There was a PM 2.5/5/10 sensor onboard, but due to some SPI issues, it was last minute put into local recording only mode (it has some internal storage it can just log to).

Probably worth those extra fields getting cleaned up though before next flights.

Mike Sharps

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May 23, 2023, 4:35:04 PM5/23/23
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Might be worth mentioning that in order to have the extra telemetry fields on sondehub you will need to add an encoded  fields list as the last field in your tracker telemetry. Dave Akerman proposed and implemented  this protocol in his range of devices and I. have added it to my trackers and receiver as well. It gets around the issue of Sondehub's lack of support for the old HabHub flight doc's.
full details on Dave's blog https://www.daveakerman.com/?p=2987
your telem should then look something like. :> 
payload = $$FLOPPY445,1271,20:29:46,53.226883,-2.506615,46,0,67,8,28,24.25,1023.68,47.03,3398,0,3,0,012345786ABRS9*E24A
The 012345... being the field in question.
Mike.



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