Launch Announcement - Ross On Wye Sunday 28th July 2024

[David Akerman]

I'm planning a launch for this coming Sunday, midday (very ish).

BABBAGE: 869.850MHz, Mode 3 (Explicit, 250kHz b/w, SF7, EC4:6, LDO Off).  Telemetry and SSDV.  Leave AFC off.  The payload will switch Tx off for 5 seconds at the top of each minute, for an uplink (to request the re-send of any lost image packets).

Predictions are for a fairly local landing.  Expected burst altitude around 41km.

I'll probably set up a video stream of the launch.

Dave

[David Akerman]

Thanks to those who helped receive this flight.  I know that not everyone has 868MHz LoRa hardware, but with the limited range I was very glad of the help!

For some reason my SSDV uplink didn't work this time, hence the missing packets, and I'll look into that this week.

The flight profile was one of those typical summer ones with high altitude easterlies cancelling out the lower level westerlies, so once launch was over it was a pretty relaxed affair.

Fill and launch were surprisingly challenging, as the gentle wind we'd had prior to fill suddenly turned to strong and blustery within seconds of me starting to put the gas in the balloon.  We were expecting 3-5mph winds (from the BBC website) but this (from my PWS) is what actually happened:

So I was keen to get the balloon filled pronto, to get it up off the ground and safe, or safer, from hitting something and bursting.  The result was that by the time the wind had dropped enough for me to get an idea of the neck lift, I'd overfilled.  I wasn't too fussed as the extra gas would help with the launch in the strong wind.

With the balloon filled I powered up my tracker (an old PITS Zero with a V3 Pi camera).  I don't recommend those cameras for HAB as they have focus issues, but in this case the camera had something close by to focus on so that worked out well.  Anyway, when I checked the transmissions there was no SSDV at all.  The camera was connected OK but the little plastic clip on the Pi Zero wasn't in properly, and that was the cause.

We had further delays trying to launch the thing, as the wind kept up for a long time.  In the end, the wind eased off enough for me to feed the balloon up as quickly as I could, and the actual launch was fine.

The result of the overfill was an average ascent rate more like 6m/s than 5m/s, and with that typical increase during flight that H2 has.  Putting 6m/s back into Steve's predictor (which has options for "Hwoyee 1600 according to spec" and "Hwoyee according to what they do in practice") gave a burst a bit below 40km assuming the usual Hwoyee over-performance.  In the end it was about 3km above prediction, at 42,738.8 metres, which was impressive.  That was a 10-year-old vintage Hwoyee, clearly!

Dave

[Steve]

Amazing performance from a 10 year old balloon -- Hwoyee do seem to out
perform other brands - one wonders exactly what additives Hwoyee are
putting in to keep latex that long - Kryptonite perhaps.  I've seen
other brands brown and crusty when they are old,  I recall a few such
balloons expanding asymmetrically - where one area would bulge more than
another.

I have a few Hwoyee 1600s of that sort of age if anyone is interested (I
used to keep balloons from batches that were turning in higher than
expected altitudes) - drop me a line if anyone is interested in some.

    Steve

On 29/07/2024 09:12, David Akerman wrote:
> The result of the overfill was an average ascent rate more like 6m/s
> than 5m/s, and with that typical increase during flight that H2 has. 
> Putting 6m/s back into Steve's predictor (which has options for
> "Hwoyee 1600 according to spec" and "Hwoyee according to what they do
> in practice") gave a burst a bit below 40km assuming the usual Hwoyee
> over-performance.  In the end it was about 3km above prediction, at
> 42,738.8 metres, which was impressive.  That was a 10-year-old vintage
> Hwoyee, clearly!

--
This email has been checked for viruses by AVG antivirus software.
www.avg.com

[David Akerman]

Yes I've seen that (browning) too, but this one looked perfect.

It's my last HY1600 so I'll put an order in shortly.

Dave

--
You received this message because you are subscribed to the Google Groups "UKHAS" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ukhas+un...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/ukhas/6f70892c-06ae-4702-a52a-84d72823a1b5%40randomaerospace.com.