Freesteel Blog » Weekends

Thursday, July 28th, 2016 at 11:25 am - - Flightlogger, Hang-glide

I don’t know which direction to go now, so I did a quick bit of video editing of a flight in Italy. I got plans to write this story up in more detail if I can get over the writers block that’s making it difficult even to complete my logbook.

I am losing control over direction. I should be running the machine tool on something, to keep it oiled. But then there is the GroundWindow app that I’m converting to work in Yorkshire with the cave data we have there. And also analyzing my flight logger data, which I seem to put hundreds of lines of code into a week, but continues to get nowhere. It’s strange.

The WebGL situation with GroundWindow is diving into a real rabbit hole. I have long known I needed to learn how to code GPUs, but could never find a way in. GPU technology, as I have observed, makes much of the software engineering I have done over the years entirely redundant.

Last week I spotted that the genius who made the early webgl water demo I’ve been hawking around to prove my point finally written a blogpost about one small aspect of the demo.

In it he referred to another blog about the GPU graphics pipeline (written in 13 parts), that I am trying to work through. I’m getting about 50% of it at most.

The question then comes down to whether there are any meaningful new machining algorithms that can be built based on this technology, using OpenCL or whatever, because that’s one of the few things I am uniquely qualified to research better than most — even if I can’t persuade someone with a budget to pay for it.

That’s just normal stupidity and mis-allocation of capital by those in control of developmental budgets.

For example, let’s take the massive public engineering program called Trident just authorized by Parliament this month to build four nuclear powered submarines to provide that essential round-the-clock service of threatening indiscriminate annihilation to targets unknown at a few minutes notice.

Now some MPs believe that investing in high technology is good merely for the sake of it, like Toby Perkins, who said in the debate:

The most depressing exchange was with representatives of the GMB union in Barrow [where the submarines are built], when… [the MP] for Islington South and Finsbury suggested that they might like to make wind turbines instead. They politely but firmly informed her that they were involved in designing and producing one of the most complex pieces of technology on the face of the earth, and that wind turbines had already been invented.

Setting aside the fact that nuclear submarines have already been invented too, the difference is that wind turbines produce electricity, which has value. Military nuclear submarines, on the other hand, have no return on investment. They are not put for up sale as part of the international arms market to foreign dictators (and you won’t get away with selling used ones to Canada again). The subs are not applicable to a modern resource war, like the invasion of Iraq where the plan was to win the wealth back by stealing their oil, because the victims don’t have navies. And there is no program for technology transfer, given that the nuclear power industry has been entirely outsourced to France on a strategic level

In fact all the engineering being budgeted for this program is wasted and will be subtracted from the engineering brains available nationally, just when we need them most and the availability of immigrant engineers is going to be choked off.

Nuclear war, in terms of the way the politicians handle it, is worse than low-grade Science Fiction. So at this time I picked up the 1964 Heinlein post-apocalyptic novel Farnham’s Freehold, where an all-out nuclear war blasted the Goldwater republican right-wing Americans (with the same mind-set as the author) two thousand years into the future from their private fall-out shelter. Here’s one of the characters in the future civilization looking back at the recorded history trying to interpret the events:

The war itself he didn’t find hard to believe. He had experienced only a worm’s-eye view of the first hours, but what the scrolls related matched the possibilities: a missile-and-bomb holocaust that escalated in its first minutes into ‘brilliant first strike’ and ‘massive retaliation’ and smeared cities from Peking to Chicago, Toronto to Smolensk; fire storms that had done ten times the damage the bombs did; nerve gas and other poisons that had picked up where the fire left off; plagues that were incubating when the shocked survivors where picking themselves up and beginning to hope–plagues that were going strong when the fallout was no longer deadly.

Yes, he could believe that. The bright boys had made it possible, and the dull boys they worked for had not only never managed to make the possibility unlikely but had never really believed it when the bright boys delivered what the dull boys ordered.

Not, he reminded himself, that he had believed in ‘Better red than dead’–or believe in it now. The aggression had been one-sided as hell–and he did not regret a megaton of the ‘massive retaliation’. [Chapter 14 p190]

Two things: Being ‘red’ is actually a temporary phenomenon (unlike radioactive and dead). Just ask the East Germans.

Secondly, the Cold War was stoked and prolonged by the dull boys in America, from their endless lies about the missile gap, to their intrusive U2 surveillance flights across Soviet airspace that utterly wrecked the four powers peace summit that had been scheduled to de-escalate the Cold War in 1960.

Ironically, those U2 flights were collecting intelligence that proved there was no missile gap whatsoever, yet the President and Presidential candidates continued to lie about Soviet capabilities to paint their political opponents as “weak on defense” in the forthcoming election.

It’s the old game of elites clinging to power by scaring the bejeezus out of the public, and then offering dangerous answers that don’t work, and successfully displacing consideration of the real problems at hand that require solutions they don’t want anything to do with.

The problem with our thinking is that future exists only in the human mind, and we are not carefully discriminating between the challenges ahead that are entirely within the various states of mind, such as the threat of war and the causes and consequences of property distribution and financial debt– and challenges out there in the physical world that are not going respond to any of our puny beliefs, like climate change and the polluting energy systems in the modern world.

In a sane world the Committee on Climate Change would get the £200billion engineering budget to start building the stuff we need now, like tidal barrages and CCS, and the nuclear warriors would instead sit in smoky committee rooms writing strategic reports on paper and getting sent off to international conferences to sign treaties– in other words do the sorts of things that would solve those problems completely.

That’s the way round it should be. But it’s like we think we’re looking through a window on the future, and instead it’s just a mirror reflecting the past behind us. And this would be fine, if it weren’t for the point of reality that time does not in fact run backwards.

Thursday, July 14th, 2016 at 7:57 am - - Cave

To distract myself on the underground camp of terror I stripped down my hang-glider logging device and took it down with a string of temperature sensors, barometer, humidity sensor and light cell and stuck it in a box in the corner with the string dallas temperature sensors extending out along the clothes line some ways from the tent.


The tent was a home made affair designed to be light and sleep four people. The fabric was slightly water resistant. There was immediately a condensation problem with cavers waking up in the morning with the sleeping bags soaking.

As a consequence people began leaving the front door to the tent wide open which meant that it was not a lot warmer inside than out.


Key: The red vertical lines are in increments of 5 hours, horizontal lines are increments of 1 deg C (when applicable). Cyan lines are the temperature measuring devices, some inside and some outside. Cave temperature was around 2.9degrees, while inside the tent it got to 5degrees in the early part of the night.

The four lumps of yellow on the lower line are from the light sensor and represent: (1) first arrival at camp and setting up the logger, (2) return to the camp after an afternoon of caving, (3) waking up in the morning, (4) returning back to the camp for packing up and leaving.

There is a sudden spike up in temperature when I dropped some of my spare clothes onto a sensor that I took off ready for the long climb out.

The upper red trace is the humidity x 0.1 and varies between 95% and 88%. The middle white trace is the temperature logged by the humidity sensor itself. The lower white line below the zero is the barometric reading, which spends its time around 88000millibars corresponding to about 1200m altitude.

Finally the yellow line is the dewpoint temperature, which varies between 2degrees and 4degrees.

Some condensation was briefly encountered when we first got into the tent slightly sweaty (and the yellow and white lines crossed over). For the first half of the night the dewpoint temperature differential was at about 1degree. Then someone woke in the middle of the night and pulled the tent door much wider open which dropped the humidity by 2% and the inside temperature by 0.75degrees, but the differential widened slightly.

I don’t know why the temperature varies so much during the night. Maybe it’s overall constant, but there are slight changes in convection currents that vary this. I should string the sensors all round the inside to see how it cross-varies.

It takes at least an hour for stability to resume when we leave the camp. Humidity rises as the temperature decreases.

Would the story have been different with a more porous tent fabric that could let out the water rather than one designed to be impermeable to liquids? If this was used we may have been able to raise the temperature inside the tent high enough to be clear of the dewpoint value, even though there is not much room below the 100% mark.

There should be a calculation of number of breathing and sweating bodies, the inside temperature and the and rate of exchange of air that provides for an optimal size and location of vent holes for the night. However, it’s difficult to find anywhere in the world that is this cold, humid and miserable for any experiments.

There are constant drafts around the cave which leave their mark in the rock formations. A set of barometers carefully synchronized, both outside and inside the cave, could produce an account of the total volume of the cave and its effective entrance surface area by modeling the flow of air molecules between these different reservoirs. This would tell you what percentage of the cave has been found. Experiments could be done on man-made tunnels whose dynamics are simple and volumes known. Higher frequency induced pressure changes might also be detected given that the bluefly is measuring at 50Hz.

Wednesday, July 13th, 2016 at 8:54 am - - Cave, Uncategorized

The weather turned caving, so I went underground two times. The first was to the shallow Balconyhohle (60m entrance pitch, then run around horizontal passages). There is a snow slope going up towards the surface that Andrew had a poke up.

Then someone showed me a demo of virtual reality using WebGL on a smartphone in a webpage, and I spent a couple of days coding the obvious idea I’d had years ago of putting all the cave data into a 3D model, using the GPS position and screen orientation to project it so that your phone acts like some kind of X-ray vision through the ground.


We used this to find a corresponding hole above the ground, which had a snow slope in it going down. It was a known hole in the database (identified by the metal tag drilled into the rock beside it) but with no record of exploration. Andrew looked at it the next day and couldn’t get down through. Later on he went underground again with a shovel and dug upwards as far as he could reach, but it still remained plugged.

Maybe if we rigged up some kind of a shelter over the hole to stop more snow falling into it, it could melt out in a few years. Something like some metal bars and planks of wood higher up to keep the new snow from getting out of reach of the sun so that the spring meltwater pours down and erodes away a bit of the snow plug each year.

Then, because I didn’t want to do much caving, I decided to go on the deep underground camping trip, which was far, far too deep with a lot of nasty scary rope rigging on the way down and up that kept me in a state of terror for hours on end. This is not as illogical as it sounds. Caving is horrible, and it takes many days for the memory of how horrible it is to wear off (like the memory of a very painful hang-over) before I am prepared to do it again. But once I’m down there I haven’t got a lot of choice.

Becka took her phone down to the camp (at -600m in Kraken chamber) and it took considerably better pictures than the fuzzy gopro I had.
There was a cross-over with the previous camping group, which is why there’s so many people in this image.

This is one of them starting up the big loose pitch out of the chamber, which begins with a 60m freehang, and then lots of rebelays on a blank rock above a soily bouldery slope that you keep kicking stuff down from. As a consequence only one person can be on the rope at a time and it takes ages.

The passages were enormous and we explored and surveyed about a kilometer of cave.

There were some surprising formations, including this pickled gherkin sized helictite with a drip on the end that never quite fell from it, because the mud was untouched below it.

When we three finished our two days and one night stint, the next team came down and met us at the tent while we were stoking up on food for the horrendous climb out (lots of pathetic whimpering from me) and overdosing on our salt quota (according to the packet, the instant risotto meal for two I ate contained 11g of salt). Somehow on our ascent one of us pulled the rope up after us and accidentally hooked it over an isolated rock ledge well out of reach, which meant that this team were trapped underground until the full-expedition rescue was called out owing to them being overdue.

Luckily, Becka and me were miles away in Griefenburg by this time, with her on her new road bike, and me playing in the low clouds. The sad thing was my favourite pizza joint in town had closed since last summer, and the restaurant we went to instead was a bit crap.

Back at the expo the next day, Becka went straight up the hill while I attempted to get in another flight. It didn’t go too well, and I nearly crashed off the ramp, probably because I’d kept the nose too high without a headwind to guide with wing position. I barely got away with it and haven’t dared look at the photos yet. Not good memories to leave this place with.

I calmed my nerves for a couple of days by coding the groundwindow application and getting to know something about writing GLSL shader technology. It’s pretty stunning, and it makes the phone quite hot from all the computational power.

Saturday, June 25th, 2016 at 8:38 am - - Hang-glide 2 Comments »

I did it! I f***ing did! The mission to fly from the Loser to the Dachstein and back as mentioned in my Skywings article last year.

It was third day lucky. First day was a practice day, which somehow got me to Grimming and back in a four hour flight.

Second day I went for it because of a very good alptherm prediction, and fell out of the sky from 3000m to ground level in Bad Mitterndorf in a matter of minutes by attempting to punch through huge valleys of sink on my Sport2 due to stupidity, ignorance and nothing else. I misjudged the winds and there were no clouds to remind me where the thermals were — ie not in the valley.

On the third day alptherm gave an even crazier thermal forecast, the like of which I’ve never seen for this place.


I wonder what that german writing at the bottom says. Probably nothing important.*

I held back as two topless gliders took off at 12:30 and one of them went down. I knew 1:30pm was my magic time. The alptherm values are in UTC (add 2 hours for local time), so it really only starts cooking on at hour 1pm, before which it feels like there is a pause in activity.

And I went straight up to 3000m where the valleys and mountains are just minor details and threaded my way from cloud to cloud.

The sky gods sent the cunimbs onto massifs beyond all four corners of the flight and while the Dachstein gruppe remained miraculously clear.

Then it was off the the Grimming, arrived from the thermal hotspot to the east but unfortunately below its peak and was too intimidated to do any circling near this blasted mountain.

Luckily there were paragliders flying here and there to guide me and stop me from wussing out whenever it was feeling too extreme.
Was it a bad idea to go higher? There was a speck of a floppy paraglider up there in front of the cloud. Is it okay to fly over the 3000m peak of the Dachstein? There were two paragliders right down low over it.

How is it possible for something this amazing to continue? Just a set of simple wings on my back in this crazy place. This is an enactment Niven’s third law including commentary, which may predate the invention of hang-gliding:

3) Mother Nature doesn’t care if you’re having fun.
You will not be stopped! There are things you can’t do because you burn sugar with oxygen, or your bones aren’t strong enough, or you’re a mammal, or human. Funny chemicals may kill you slow or quick, or ruin your brain … or prolong your life. You can’t fly like an eagle, nor yet like Daedalus, but you can fly. You’re the only earthly life-form that can even begin to deal with jet lag. You can cheat. Nature doesn’t care, but don’t get caught.

I got there. There were big anvil clouds to the south darkening the whole horizon. This is the way I am going, across this sea of rock and snow back to Altaussee.

It was like a solid glide for 20 minutes, then a thermal off a corner buttress so I didn’t have to squeak through the Obertraun valley, then another 20 minute straight glide to the Trisslewand that had a huge cloud hat on that worked. There was nothing else between.

I decided to come down before anything went wrong and was actually able to phone the cavers sitting in base camp to tell them to look to the sky. They couldn’t hear me, so I texted them instead. Texting while flying is about as dumb as texting while driving, but the air was quite open at 2200m.

Becka cycled up and helped me carry down from my favourite landing field behind the campsite. I celebrated with a beer. It still gave me a headache. Back to earth. This is now the state of the campsite. The noise is awful.

* Translation: At the moment thunderstorm and precipitation symbols can’t be shown due to technical reasons.

Wednesday, June 22nd, 2016 at 5:46 am - - Cave

I cried at the state of the campsite in Austria when we arrived this year. It looked like part of the Amazon Rainforest — clearcut and still raining.

The plan is to be here for about six weeks, and it’s not looking like a great idea. Only about a quarter of the people have arrived so far, and even the cordoned off area is pretty churned up. I pitched my tent on a gravel patch by hammering in nails to guide the tent pegs.

So, to cheer myself up I did some coding, and wrote stl2png, a program to slice STL files directly into PNG images for use with an SLA printer.

This is an example of a generated slice of the two chamber whistle someone has been printing a lot of in DoES.

(The wifi internet for the computer is pretty poor around here in the campsite, and there is no mobile tethering allowed when you are abroad, so I am unlikely to get much blogging done for a while.)

Monday, June 13th, 2016 at 2:14 pm - - Kayak Dive

I haven’t dived near Skomer since 2008 when we arrived just after Bristol University left a day early, having been drenched by the rain. This time we successfully caught them on the last day of their trip and tagged on for a dive on the north face of Tusker Rock in Jack Sound, which is known for having a very short slack window.


We paddled out there for the dive at 1:10pm, but the Bristol boats didn’t show up from around the corner till 1:28pm — very late. Everyone blamed everyone else for the faff, and I didn’t feel confident with going in here at this crazy place alone without being really sure we got the place right. (The north flowing current is menacing as it descends down to 50m as it leaves Jack Sound.)

Bit blurry, but there’s a dogfish swimming past Becka

Rather too soon, we got washed off the rock by the south flowing current and had to come up.

We had an excellent extra dive in the calm waters of Martins Haven where the scallops were stacked like bricks (apparently there’s a fine of £50,000 if you’re caught taking one of them). Lots of lobsters, spider crabs, and nudibranchs. The camera was of course out of battery by then.

Next day we headed for Octopus Reef on Dinas Head, where I’d met Red Dragon Divers on a sea kayaking trip in 2012. This was a chance to tick that one off, although the visibility was very poor from the plankton bloom. Becka found the octopus on the first dive, after we’d fallen off the reef onto gravel and were swimming round in circles at 13m. Spent the night in Parrog (where we’d kayaked from), too flaked out to go to the pub.

Final day had us paddling out of Gwbert by Cardigan to Cardigan Island to try and dive the SS Hereford. Unfortunately, the westerly swell was picking up quite a bit, so the sea was a little crazy out there and not a great place to try a dive on a shallow wreck. So we dropped in round the corner in the sheltered waters that was very much in its pea soup stage of plankton (little green translucent peas of algae everywhere), bothered a few lobsters, dogfish and spider crabs, before paddling onwards to Mwnt visiting all the sea caves in the coast. The carry-out was not as bad as it looks in the photo.

Becka left me at the tea shop while she walked back to fetch the car. The lady running it explained that the dolphins can normally be found off the north end of the beach, whenever you see a gannet flying there. She guessed they were driving the fish into a sand-bar, and the gannet was picking the ones off that came to the surface.

We can check it out next time we go down there and have a third attempt to do the Hereford wreck when we are sure the sea state is calm enough to make it worthwhile. Kayak diving wins again.

Wednesday, May 25th, 2016 at 12:58 pm - - Hang-glide

This was Sunday (yesterday) on Tailbridge Hill while Becka and friends were attempting some 80 mile massive cycle ride including a race up Great Dun Fell (844m), somewhere square in the middle of that dark grey wall of rain and hail to the north of me.


They didn’t make it. I suspected that something bad could happen in that area on an otherwise sunny day because of the RASP forecasts:
They were to the NE of Kirkby Stephen in the blue, and I was to the SW in the place with the nice thermal updrafts. I already knew no one was interested in my weather observations if it could lead to a change of plans, because they’d all been on a futile journey walking up a hill to a flood-prone cave on Saturday when I knew two strong cold fronts were predicted to pass overhead and make everything miserable.

I got into my own spot of hail up at the clouds at 1300m over Mallerstang Edge late in the day, and it was nice witnessing this three-dimensional field of white pixels streaming past.

I don’t have time to edit any video, so here is a video with a bit of hail in a flight last month from Builth Wells.

I had to do a better landing yesterday, because in Yorkshire the field boundaries are made of rocks.

Thursday, April 28th, 2016 at 12:04 am - - Flightlogger, Hang-glide

Well, the hang-gliding has been quite lovely. But the logger appears shot to pieces.
I still don’t know what I am doing when I get to cloud-base, which is probably why I plummeted out of the sky shortly after this picture was taken.

As soon as I took off, the barometer stopped communicating most of its data.
This is the device I lavished so much time on isolating it from the rest of the electrical circuit and arranging for it to bitbash the information back through an interrupt pin.

It could be some timing issue, or whatnot. No way to debug it. Luckily I got myself a Bluefly vario which does the same thing of reading a MS5611 barometer on a tight 50Hz loop and transmitting it back to the main board. In the Bluefly’s case it’s for the purpose of running a Kobo/XCsoar system. I’ve just given up on the one I built as it’s too inferior to simply running XCSoar on the phone where I’ve got colour and more or less know how to use it.

Luckily the Bluefly also sports a GPS and works through a serial port, so I’ve yanked off the Adafruit GPS breakout board and bodged the wires to insert the Bluefly in its place.
Then there was a small matter coding it up using a complex state machine to program the GPS module through the Bluefly pic processor to get it to read at 10 times a second.

But then the BNO055 orientation sensor played up and decides to shutdown at unexplained moments for unexplained periods of time.
The white vertical lines are 10 minute intervals, and there is a green dot for every successful orientation reading, with y-value proportional to the time since the previous reading, so I’m getting gaps in the data of half an hour in flight.

I’ve produced a reset timer to try and start it off again if no data comes through for 20 seconds.

Anyways, here is one of those nerve-wracking close encounters with the ground during the flight.

Tuesday, April 19th, 2016 at 11:29 am - - Hang-glide

If you look closely you can see the grin behind the helmet.
There was nothing especially epic about this XC flight from the Long Mynd to Clee Hill, except a masterful get-away from the slope in nil-wind with just one thermal during which I miraculously stayed on top of all the paragliders. Also there was a very low-save.

I took off at about 1:30 during the period when the wind was less than 5mph and sometimes coming from the SW. This trace is off the Long Mynd Gliding Club weather station:

No one could explain why there was so little breeze to make reliable ridge soaring possible. Meanwhile, there were champion pilots flying 100s of miles on seven hour flights on that day, which one must try not to feel bad about, when I “only” managed to stay up for an hour and a half.

One thing I did learn for sure is that I utterly depend on the thermal assist of the XCSoar running on my android phone. (That Kobo kit you see in the video is going in the bin.) The magic went away when the phone ran out of batteries; my thermal tracking abilities went out the window from that moment on. So this flight (and hopefully many more, when I sort out an extra power supply brick for the phone) is dedicated to Lines 145 to 202 of XCSoar/src/Renderer/TrailRenderer.cpp which was able to direct my search for lift whenever I lost it. This is the section of the manual describing the critical feature:


A couple more regrets. I didn’t make cloudbase by at least 300m, according to the dew point measurements. And the barometric reader, based on bit-bashing and interrupts, is completely shot to pieces by the overload on the microcontroller from acquiring so many other inputs of data. Only about 1% of the readings are getting through. I’ve got to come up with some other answer, and I don’t have a lot of time in a week when we’ve got some help doing something about the state of the kitchen floor.

Wednesday, April 13th, 2016 at 12:39 pm - - Hang-glide

Thought I’d scan and upload my article about flying in Austria for folks to download:

JGTskywingsLoser.PDF (7Mb)

Individual pages: