Freesteel Blog » Weekends

Tuesday, March 17th, 2015 at 8:39 am - - Hang-glide

Here I am at a climbing wall in Bristol, having balked at the price and instead sat in the cafe. They ought to have a discount rate for people don’t actually like climbing. Here’s what I enjoy instead. (I am so predictable):

pontwales

Brrr, it was cold in grimmest South Wales on a grim Saturday when all the colours are grey and the light makes everything flat. I enjoyed a sublime hour long flight above Pontlottyn, even though I didn’t go anywhere except soar up and down the ridge alone and then top land in a howling gale.

My box of tricks is in the 3D printed purple box on my left next to the airspeed indicator. I’ve not had the chance to do anything with the data except plot it and go: “that’s pretty noisy” at the accelerometer data. I have plans to extract consistent correlations, barometer vs altitude vs temperature, bar position vs wind speed, roll angle vs turning rate registered on the compass, and whether I keep diving out of turns because I don’t have enough speed and control.

Unlike my so far doomed attempts at manipulating house and fridge temperature data, this flight dynamical system is memory-free. The same temperature, pressure, windspeed, and wing angle at any time of the flight should result in exactly the same response. Deformations of the wing are brief and temporary. This is not the case for the fridge where every cycle begins with a different temperature distribution within the dense cabbagy foodstuffs and chemical pumping machinery.

Subject to instrumental noise and turbulence, all the data should be with me, and I can only hope this isn’t going to end up as just another one of my expensive failed software projects that looked plausible when I began, but then crash landed in the trees.

Wednesday, March 11th, 2015 at 3:35 pm - - Hang-glide

In spite of being up to lots of things, I’ve not been very interested in blogging of late.

I got my first flight of the year — a 3 minute top-to-bottom that began with a nil-wind terror swoop on take-off, followed by my almost forgetting to unzip the harness on landing due to being distracted by the sight of ducks paddling around in one corner of the water-logged field.

landingshadow

Here’s the data stream from the landing.
landingdata
Vertical lines at 5 second intervals. Yellow for barometer (air pressure rises as I descend), red for airspeed, cyan for GPS ground speed (seeming to correspond), white accelerometer pitch measurement, showing the pathetic flare coming into landing when all the speed drops off. The previous hump may correspond to the final approach turn (you have to push out to tighten the turn to a turning circle of about 35metres).

takeoffdata
Here’s the take-off sequence, with a slight push-out which was not held long enough, so I dropped very fast. The yellow for the barometer briefly goes below the starting value showing that at one time I got a bit of lift and could have been almost half a metre above take-off.

All in all, quite disappointing, but I’m glad to have some data to work with from my electronics device. I’m going to really appreciate the next flight when I stay up for a bit.

hgelectronics
Oh yeah, here’s a close-up of the one corner of my dog’s breakfast electronics project.

boxprinting
Luckily, 3D printers can print anything — including the abominable box I’ve “designed” in OpenSCAD to cram that electronics stuff into.

machtooldoes
Meanwhile, all this will probably be shelved due to this widget showing up in the hack-space this lunchtime. More later.

Sunday, January 11th, 2015 at 9:10 pm - - Hang-glide 1 Comment »

By not including a datasheet with their airspeed probe, Brauninger/Flytek gave me the pleasure of two successful days of hacking involving an oscilloscope and much experimentation to work out its parameters and build a circuit to exploit them.

I bought this thing as an optional add-on to the Flytec 6030 (which I’ve never got to grips with) back when I had more money than sense. I wouldn’t have got it for the purpose of reverse engineering like this because I couldn’t do electronics then, and anyway I’d have rated the chances of success as quite low.

Nevertheless, by applying various voltages and different directions and blowing on the propeller to get a response, I established that if you apply a positive current on the tip of about 1Volt (and ground the other connection), the device exhibits a resistance of between 11200 Ohms and 12000 Ohms, depending on the position of the blade.

This was a job for a Wheatstone bridge:
wheatstonebr

You can actually see the voltage differences (in millivolts) over 1/12 of a turn of the propeller:
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Tuesday, December 30th, 2014 at 2:27 pm - - Cave

This trip round the Lleyn followed on from last year’s Avoiding Nadilog by Walking in Wales. In retrospect nothing much happened. But it was exciting at the time due to the lack of planning and the risk of things going wrong.

whistlesands
Our white Xmas on Whistling Sands

Departure was delayed till the morning of the 24th because someone couldn’t possibly miss their 14th digging trip of the year in ODB. Anyway it was raining and we weren’t packed yet.

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Sunday, December 7th, 2014 at 4:14 pm - - Cave, Kayak Dive, Machining

I’m going to do some other coding, now that I got this result. The code would fall apart if I touched it again.
impslicesubdiv

Next on the list of things to do is clear out the vast quantity of rubbish left in the code, completely redo the subdivision loops and make the logic robust, apply it to multiple z-levels and plot slices, then make it test against edges and faces (not just points), and package it into a self-contained (but very slow) version of the slicer.

I don’t know how long this will take, as there are many other distractions available.
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Thursday, November 6th, 2014 at 1:08 am - - Hang-glide

Just when I thought it was over for the summer, there came a chance to go flying at Llangollen. It seems there are more hang-gliding conditions this year than kite-surfing conditions, which is not what I’d hoped.
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Wednesday, October 22nd, 2014 at 3:02 pm - - Weekends

How does anyone hold down a proper job?

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I just got a “Hello world” program working out of a pair of Jeenodes kicking around in the cardboard box left over from the Housahedron project before they migrated to Berlin. Of course, there was no documentation for how to plug in the interface into the Jeenode, and I had to get Adrian’s help.

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Friday, October 3rd, 2014 at 11:55 am - - Kayak Dive

Aside from having to get up at five in the morning and Becka not skiving the day to come along on the boat, it was a perfect trip out.

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Liverpool is starting to look a lot like the Esbjerg did the first time I caught the ferry over to Denmark in 2003 and saw spinning wind turbines everywhere.

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What amazing kit — the original gopro camera still hasn’t broken. I record these videos for the same reason I write phone numbers down in a book or keep a trip log: I can’t remember things well enough.

The water was pretty warm at 16degrees. I wore all my layers under the drysuit anyway and barely felt a thing swimming around. It was like a dream. I didn’t take any lobsters, but the others did. The conger eels stayed in the cracks while the tompot blennies came out to play.

stars
The second dive was on the Calcium where there was one large cod and more starfish than grains of sand.

There was a surprise party in the evening, which I thought was for my birthday, but wasn’t.

Wednesday, October 1st, 2014 at 12:28 pm - - Weekends 1 Comment »

I’ve always hated fell walking. It’s character building, good for a family trip out, and uses lots of time. It’s boring. As a kid you’d rather spend the day on the beach building sand castles or learning to windsurf.

Yes, there are so-called wonderful views. But they’re not the point. If they were, then how come the walk doesn’t get cancelled when the hills are in fog? We don’t try to windsurf when there’s no wind.

Admit it, you’re doing it because of tradition and for the pointless exercise. It’s a particularly painful exercise because you’re only using the lower half of your body, pounding it for hour after hour with hardly an interval of rest. At least when you go cycling there are those downhill bits where you cover the ground and your muscles have time to recover.

scafellfog

The idea of the Lakeland 3000 is to walk all 4 peaks in the Lake District that are over 3000 feet in altitude in 24 hours. This is a stupid idea, but that doesn’t stop people from getting hooked on it, and then inviting Becka and me into the plan. It was the caving conference weekend. The caving conference is always the same each year. One thing lead to another, and I found myself walking towards Keswick town square at 10:30pm on a Friday night after an extremely grumpy day due to a headache and no sleep the night before.
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Wednesday, September 10th, 2014 at 2:28 pm - - Kayak Dive

We went away for some kayak diving in Pembrokeshire over the weekend. I wanted to dive on the north coast from St David’s, but the north wind had picked up, so we directed ourselves to the south coast and going out of Solva after camping on Friday night in a layby to the east of Felindre Farchog on the A487 that had bogs. A useful discovery after drawing a blank going down some of the single-track back roads near there at one in the morning.

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There’s not much to report on the diving. No amazing sights. Not a conger eel, or dolphin, or trigger fish, or even a spider crab. It was mostly kelp, gravel, silt, and a few pollacks. Everything had gone away for the winter even though the water was as warm as it is at any time of the year. The energy for life comes from the sunlight, not from heat. The cliffs were empty of birds who had abandoned their ledges that they had spent the spring and summer painting white with guano.

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Solva harbour is pretty dry most of the time. After waiting 5 hours for the tide to rise, we dragged our boats out when it was at this level.

straploose
Becka is unimpressed by this strap coming loose on to which she had tied her canoe for this dive on the south side of Green Scar. There were gusts of wind on all sides of the island, even on this seaward side which was supposed to be sheltered. We did a shallow short dive, then got back on the boats and paddled into the wind to get back to the coast. There had been a slight concern we weren’t going to make it after going off-shore like this, but there wasn’t a problem.

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We camped at Cairfai Farm, the low-carbon tents-only campsite south of St David’s on the coast, having left our kayaks on the beach so that we only had to carry the empty tanks up the steps to change them at the car.

anchorgeorge
My old set of electronic charts are broken, but after looking at a chart of Ramsey Sound on the wall of a pub I spotted a wreck in Porthlysgi Bay which I could look up accurately on the internet, which meant we could dive the wreck of the St George the next day.

I don’t know anything about it, except there were a lot of tall bits of metal which Becka had to thread the kayak anchor line around.

After this, the options were to either drift round on the current into Ramsey Sound, or go back along the coast for a final dive off the east side of Porth Clais where there was a deep section of sea bed close in shore, according to the charts (about 13m).

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Being chickens, we opted for the latter. I’d also told the coast guard we’d be off the water by 6pm, so there wasn’t much time left. I always inform them now after getting call-outs due to walkers who see us fall in the water and start thrashing around trying to get our kit on before appearing to drown.

It was a long drive home via the chip shop in Fishguard. I still need to come back and do that north coast again when it’s in shelter.