Freesteel Blog » Hang-glide

Wednesday, July 19th, 2017 at 10:05 am - - Hang-glide

Sometimes things you’ve always dreamed of happening grab you by pure chance.

beckabefore3

I could have organized this event at great expense in England on some boring ridge soaring ridge, but I got unlucky during a competition, and then got real lucky to do this.

At the start of the day I was mixing it up at cloud-base with all these competition hang-gliders.

beckabefore1

And then 20 minutes later I got found out and scraped down into a wheat field 10kms to the north of take-off.

beckabefore2

Luckily one of the other competition pilots came down near me, and his retrieve driver (who, unlike my retrieve drivers isn’t more often retrieved by the pilot than the correct way round) picked us both up, and I persuaded them to take me up to the top of the hill for one last flight on Monte Cucco at the end of the holiday.

And just then, Becka was about to take off on her tandem flight which we had been rescheduling day after day during the week.

Her tandem flight lasted long enough for me to completely rig my glider, take off, and climb up to them close enough for a wave.

Later, I carried on flying for too long and landed in the field while they were trying to give the prize giving. This was delayed because of me as they needed my tracklog from my crappy flight before they could officially calculate and release the figures.

When I finally showed up I was invited to stand on the winners podium and be humiliated in front of everyone while the contest scorer squirted a water pistol at me.

Becka does not have a photo.

Tuesday, July 11th, 2017 at 4:32 pm - - Canyon, Hang-glide

I sneaked in a couple of gorgeous flights in between canyonning adventures with Becka in the last three days.

On the 8th July, while staying at Tramoniti di Sotto we did the canyons Torrent La Foce and Rio Carlo Gasparini in the morning (the latter of which is not in Si Flower’s book and should be), followed by Becka driving me up and leaving me behind on top of the hill above Meduno (Italy).

As usual, very few of the photos were any use. This is from La Foce.

And this is from Gasparini, selected based on a tip-off from 4lander.it website listed in a canyoning leaflet.

The canyon ends by joining the much larger Torrente Arzino where you bob along in the swiftly flowing blue-green crystal clear water until the climbing out point. Magical.

This is my BWG (boring white glider, which describes the top surface) on behind the Meduno takeoff. As I explained to Becka, I would be consumed by jealousy if I saw one of these and didn’t have one of my own.

And here it is being boring and white in the bottom landing field with no bent aluminium. For once I timed the flare perfectly and landed on my feet like a pro. Boy was I grinning.

meduno

The next day (9th July) we did Torrente Cosa, which passes through the property of the showcave Grotte di Pradis (see the walkways in the background). The canyoneer’s advice is to write a note in Italian saying what you are doing and hand it in at the showcave so they don’t get annoyed at people unexpectedly traipsing through, but the man in the ticket booth didn’t really know what to make of it and waved us away.

Cosa had one scary bit where I abseiled into a cauldron of water in a dark cavey section and couldn’t easily fight past the swirling current while dangling on the rope.

Then we had a late lunch before the long drive to Camp Gabrje near Tolmin.

The next day we cycled over for a quick tour of the relatively underwhelming and costly Tolmin Gorges before I caught the taxi up to the top of the Kobala takeoff.

tolmintop

The lift looked weak. For a while there was a wall of paragliders directly in front of takeoff and none getting higher. Then I saw two birds circling behind them, waited for a gap, and then thermalled directly up to cloudbase.

I lost it all crossing over to the next ridge to the West where I soared ineffectively for the rest of the afternoon not daring to venture into the mountains behind. I’d never been here before and hadn’t looked at a map. The wings felt totally natural on me. I’ve really grown to like them.

tolminlanding

And for a second time in a row, I landed on my feet with no bent aluminium.

Then I had a 45 minute walk back to the campsite in the sweltering humid heat to pack up the tent, fetch the car, drive back to the landing field, pick up my glider, and then go on a chase after Becka who was busy road-cycling to the Italian border via Bovec.

I’ve made a habit of having to retrieve my retrieve driver.

Now we are at Expo base camp in Austria where Becka is going to do a lot of caving and I am going to make myself bored until I start doing the chores that I have been putting off until now. Which includes writing up my logbook, blogging and looking at forgotten flight data.

Sunday, June 25th, 2017 at 8:16 pm - - Hang-glide

It’s been the fourth day of hang-gliding in a row and the first of the competition. My god today was something. The comp is at Monte Cucco, and the drill is you drive up the hill and get set a task in the form of a series of GPS coordinates with cylinder radii around them, and your job is to race from one to another and tag each one. Your track log verifies your score.

This is quite different from free flying, because you are forced to go to places you wouldn’t naturally go to if you were following the air — and get back from them.

Here is what the course looked like against the terrain map:

flightmap

This leaves out all the forests, cliffs, canyons, sprawling suburbs at the base of the mountains and power lines. The beginning of the journey was absolutely terrifying because any escape routes to lower ground were into wind and unlandable. You had to learn to trust the ridge lift.

I didn’t trust it, and instead spent the first 30 minutes wheeling around these scary wind turbines on take off unable to find a satisfactory way on.

windmills

Then the clouds really began suck and I raced back north to the second turn-point. The third point was the landing field. There was such an uprushing of air in the valley I could not get down. Well I did eventually, by pulling all sorts of stunts (tight circles) that are the exact opposite of efficient gliding. Then, when I gave it a rest for too long, the air sucked me right back up again.

Hang-gliding is a sport for turning long pieces of aluminium into short pieces of aluminium. That happened yesterday when I broke an upright. I have no more spares. Today I got away with skinning my knees (I’m wearing trousers from now on). Clearly I do not deserve to fly this higher performance glider (a Wills Wing U2) since landing is the compulsory part of every flight.

It’s 9pm now. I’m finding I don’t really give a damn about anything else, eg reading and answering emails, or thinking about work. It’s too hot here even if I wasn’t flying.

Bed time.

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.
(more…)

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.

(more…)

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.

(more…)

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:
(more…)

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.