Freesteel Blog » Hang-glide

Monday, June 5th, 2017 at 11:52 am - - Hang-glide

Some friendly competition in Derbyshire between hangies and paragliders on Saturday meant I got to witness the scale, organization and infrastructure of the paragliders — which included following me on xcrt.aero and being at the nearest road before I’d even had time to pick myself off the ground.

Then I was in the car for an hour as they drove madly up and down the M1 taking wrong turnings in an effort to collect three other paragliders strewn in the area.

Motto: write the logbook on the day and edit the video as quick as possible without wasting too much time.

My flight datalogger failed to record anything, so I can’t see if my thermal detector collected any signals.

Not that I had any spare brain capacity. For two hours I was continually trying to visualize and feel the structure of the air convection wafts while making constant adjustments to my circling.

I’m also learning how to stay in very weak air where you are gradually losing height — but at a slower rate than if you were on a desperate glide to nowhere — which moves you forward in time for something else to develop. It’s like skipping a turn in a card game.

Here’s a screen-grab of the livetrack24 view of my flight, which receives updates from an app running on your mobile phone.

livetrack

This is not to be confused with the latest AirWhere technology thing, also done by the paragliders recently which create an ad-hoc Lorawan network among themselves that displays their distance and climb rates of your neighbours on the network.

A small amount of additional calculation and they’ll be able to circle the ones who are in thermals you should fly to and join. This helps people haven’t learnt how to judge distances, times and glide angles.

I just cannot keep up with the tech.

Here’s some plots that I did salvage the data.

flightterrain

flightterrainside

Friday, June 2nd, 2017 at 3:32 pm - - Hang-glide

This is the follow-on of my Loser Plateau article of last year in Skywings magazine.

4 page PDF version

I should find something new to write about next time. Now that I am flying my BWG (Boring White Glider), which is a more advanced U2 I got second hand off Tim who no longer needs it because he’s got a whole hang-glider factory. Helen the bright orange HSMWorks glider is a Sport2, and I’m not ready to let go of her yet.

swp1

swp2

swp3

swp4

Thursday, June 1st, 2017 at 4:06 pm - - Flightlogger, Hang-glide

I’ve been flying around my data logger on my hang-glider and doing my own data processing with mixed results for two years now.

During this time I’ve been on the lookout for someone else’s work that I can copy.

Just yesterday I discovered the existence of Dropsondes and then Radiosondes (devices that get lifted by a weather balloon with a radio link; nothing to do with sound-waves).

The fact of their existence has been staring me in the face for years.

raspsoundings

Those little red *S* symbols in the rasp forecast are not weather symbols for sunshine, but in fact the locations of half a dozen atmospheric “sounding” stations.

Until now I’d believed they were something involving a fancy radar beams shining up through the clouds, but it turns out it’s a freaking weather balloon with a humidity, temperature and gps sensors (they don’t bother with the barometer anymore and just use the gps altitude) that radio back data for an hour and a half till the latex balloon bursts at 25,000m and the device falls under a biodegradable parachute with a 95% of never being seen again.

The US government has a complete tour of the procedure, but the MetOffice has some automated stations which assemble and let off a new balloon every 12 hours from a robot building.
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Tuesday, May 30th, 2017 at 6:11 pm - - Flightlogger, Hang-glide

First, here’s a picture of me and my cheezy grin high up in wave over Wether Fell with about a dozen other gliders last Sunday

wavegrin

I was able to generate my incomplete Tephigram as before to illustrate the warm dry air encountered way up there.

tephi

Unfortunately, the fancy Python tephigram software released by the MetOffice doesn’t work for me as it’s designed to plot graphs that go ten times higher in the atmosphere.

Tephigram is short for “Temperature” and “Entropy/phi” plot and was invented in 1915. I don’t understand all of it yet. But this science goes back a long way.

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Monday, May 8th, 2017 at 6:49 pm - - Flightlogger, Hang-glide

I’m getting tired of having “learning experiences” when I really want more “fun experiences”. But in the meantime, here goes.

On 2017-04-29 I was at the hang-gliding competition on Camlo hill in Wales, where I didn’t take any thermals over the back — like the folks who knew what they were doing — and I landed back on the top with nil points and little satisfaction.

For this learning experience, I downloaded the tracklog of one of the guys who did make it and snipped out the first 12kms of flight, like so:

darrentrack12

Direction of flight north is to the right (start of flight bottom left near (0,0)), the coordinates are in metres.

Having convinced myself I can extract the SRTM3 terrain, this is the graph of the flight altitude from the hill for those 12km against the terrain altitude:

darrentrackalt

Or you can plot the actual height above ground by subtracting the two:

darrentrackaltg

This looks like he was circling with a pretty consistent height of 350m as the air mass was carried up and down over the terrain, in a “bubble” of rising air.

Except there is no way this could be a bubble, because even if the bubble extended all the way to the ground 350m below, it would have certainly been been expended in less than 6 minutes at a rate of 1 metre per second to support an efficiently flying glider.

After 25 minutes of existence, we can rule out that it has anything to do with any packets of warmed air which may have risen from the ground 12kms to the south.

“Ah,” the usual response goes, “the glider was flying in a chain of thermic bubbles along the track of the flight, each one rising up just in time to pick up from where the last left off.”

This explanation is bogus. I don’t seem to pick up thermic bubbles that easily along my track, while the pilot that stayed with the thermal reported a continuously existing atmospheric formation which strengthened and subsided, but was always there.

I also don’t buy the idea that this structure is somehow kicking off thermic bubbles on the ground 350m below at least five minutes downwind of its track in time to reach his altitude.

No, this must be a self-contained, self-sustaining convection structure that may have been initiated by a thermic bubble, but which has clearly morphed into something altogether different.

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Friday, March 3rd, 2017 at 11:04 am - - Flightlogger, Hang-glide, Uncategorized

To be clear, I haven’t got mathematical proofs here (I don’t have the time), but the experimental evidence is quick to get.

Take the differential barometer sensor (used to measure airspeed) of the hang-glider flight logger. The Arduino code which updates the reading every 200ms looks like this:

long lastpx4timestamp; 
void Flylogger::FetchPX4pitot()
{
    long mstamp = millis(); 
    if (mstamp >= lastpx4timestamp + 200) {
        px4pitot->readpitot(); 
        sdlogger->logpitot(px4timestampset, px4pitot-rawpressure, px4pitot->rawtemp); 
        lastpx4timestamp = mstamp; 
    }
}

Why did I choose 200 milliseconds? It sounded like a good number to read it at. This is a quick way to program it to be a regular reading.

A better way is to actually synchronize it with the clock divided rather than simply add 200ms to the next time, like so:

int mstampdivider = 20; 
int prevmstampdivided = 0; 
void loop()
{
    long mstampdivided = millis()/mstampdivider; 
    if (mstampdivided != prevmstampdivided) {
        prevmstampdivided = mstampdivided; 
        P(micros());  P(" ");  P(singlereading());  P("\n"); 
    }
}

Now that code reads at 20ms rather than 200ms, but it prints a load of output which I can cut and paste into a file and read into pandas, like so:

rows = [ (int(s[0]), int(s[1]))  for s in (ln.split()  for ln in open("../logfiles/dmprapidtest.txt").readlines())  if len(s) == 2]
k = pandas.DataFrame.from_records(rows, columns=["t", "d"])

And then we can plot the autocorrelation (the covariance) with itself shifted in time, like so:

d = k.d   # just the measurement Series
dm = d.mean()
ss = [((d - dm)*(d.shift(i) - dm)).mean()  for i in range(400)]

autocov1

Let’s zoom in on the first 50 covariances:
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Saturday, October 15th, 2016 at 2:20 pm - - Cave, Hang-glide, Kayak Dive

Maybe I’ve got writer’s block. I’ve not even filled these into my logbook. I call it a hat-trick if I do a cave trip, a hang-glider flight and a dive in the same week. This is the fourth time I’ve done it. Generally speaking, the individual events are not all the greatest: the dive was pretty murky, the cave was gritty, and the flight was ridgy. Can’t complain.

The wreck of the Azmund is in Holyhead harbour about a mile of paddling out from the beach.

It was dark and murky and we didn’t find the way back to the boilers after starting on it. The wreck is huge though. Part of the metal juts out of water at low tide.
azmundwater

On the way back we discovered why the beach we launched from is not popular with kayakers — it dries out to about 500m. We couldn’t see our boats after the first time we walked back with a load to the car.
azmund

That was Saturday. There was a pleasant day out at Moelfre, with some people being terrified of the currents, but it was the wash from the joy-riding lifeboats that nearly sunk us. The image of the almost breaking 4 metre high wall of water that came upon us while we were anchored in the shallows of Rat Island a few minutes after they zoomed through the channel is going to live long in my memory. The second dive worked out well when we found the remains of the Royal Charter in the sand after groveling in the shallows among the kelp where it was supposed to be until giving up.

Then there was a cave trip to the far end of Ingleborough Show Cave (the only photo of which I have is a line of cavers getting changed on the footpath), followed by a quick escape home ostensibly to start clearing out the house, but which was in fact an excuse to be in North Wales for a flight off Penmaenbach.

penmanhg
I landed on the dwindling beach at high tide after an hour of very smooth sailing in the sea air.

frontroom

A concrete breaker was hired to smash up and take down the floor. We filled a skip with the crap a day later with some help from friends.

Now we live in a building site. Again. And it’s mid-way through October.

Sunday, September 4th, 2016 at 8:52 pm - - Canyon, Hang-glide

A bit of a bonus holiday slotted in here, with not much time or care to waste on the internet.

With three of us in the car, first we went down to a campsite near Perpignan and picked a 3.6/4 grade canyon of Llech, which was an absolute hit with all of us. There were jumps and toboggans galore, including one called the pistol that shot you up in the air 5m over a deep pool. We need to go back to that area and do the others.

llech2

Then I snuck in three days of hang-gliding off Ager with the bonus help of a retrieve driver. On day2 I tried to go behind the ridge, and it didn’t go well. I don’t know how I pulled it down into the field not of my choice without busting something more than the skin of my knee, but I got away with it.

It should have scared me more than it did. Instead my worst moments of terror were on the K5 rated via ferrata Cast Urquiza Olmo to the west of Ager by the lake.

On the third day up the hill I got an amazingly detailed briefing from some visiting British hang-glider named Al about where to go and what to expect (a huge zone of downwash behind the ridge which you can confidently get through if you start with 7000feet of altitude). It worked wonderfully on my third attempt.

tremp

Then I let myself down by nearly parking my glider on a rebar fence by curving round too wide and falling short of the field I was aiming for.
tremp2
But before that happened, the feeling came over me again where my wings became part of me for those few hours up in the sky. The joy was existential. A lot of the time I was circling with vultures. There are a lot of them about.

In the evening we picked up Becka from Lleida and then went to Torla-Ordesa to see the scenery. Unfortunately the morning buses were all full, and you’re not allowed to cycle up the tarmac road which carries the diesel buses because it’s a Spanish national park, so everything is banned even if it doesn’t make any sense. So we walked in until my foot-soles wore out on the way back and I had to catch the bus.

ordessa

Then, on the way back to France, we dropped in on the 3.2/4 rated Neste de Saux canyon, which wasn’t that great, but we were pleased because we proved we were still up to it.

Now we’re in a gite in Aspet with a bunch of cavers. Everyone is going out to run around the maze known as Felix Trombe, while I have carried on working on the ground window software, where I have implemented a real hack to create flat shading within a the GLSL GPU shading framework:

The trick is to note that the passage tube structures are made from quads which you can colour with 8 colours {-1,1,-2,2,-3,3,-4,4} such that no quad shares a colour with any of its neighbours (edge or corner otherwise). Choose the brightness factor on each quad (say it’s 0which goes:

float flatfac = max(0.0, max(max(abs(vflat4.x), abs(vflat4.y)), 
                         max(abs(vflat4.z), abs(vflat4.w))) - 510.0); 
gl_FragColor = mix(gl_FragColor, vec4(0.0, 0.0, 0.0, 1.0), flatfac); 

groundview3

(I’m now fed up with fighting with this crappy internet connection. It’s probably why I’m getting so much work done.)

Wednesday, August 24th, 2016 at 9:16 am - - Hang-glide

I spent the last three days at the washout known as the British Open Series 3 where one day out of five was flyable. This was yesterday from a hill called Camlo which is a “little flown hill, especially for hang gliders, as there is not a suitable bottom landing field”

Numpty here took off first with everyone watching and waiting because there were no clouds, and I got thrown about a bit. Luckily there were no other gliders in the air to dodge.

Then I came in and landed when things got full up like a zoo (orange glider on the 39th second of the vid).

Then I un-redeemed myself by sitting on takeoff for most of the next video until the launch window was about to close.

Most of the big boys got away during that time until I was one of just two gliders left in the air. I went in and landed just as the other one got away to a big cloud. Grumble.

Once you’ve tasted XC flying, nothing is ever good enough again.

Thursday, July 28th, 2016 at 11:25 am - - Flightlogger, Hang-glide 1 Comment »

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.