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.
clearcut

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.
V29D_Fixed_0003

(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.)

Friday, June 17th, 2016 at 1:48 pm - - Machining 1 Comment »

What was that horrible noise coming out of the closet at DoESLiverpool for about three days?

I was attempting to machine down one of these hold-down clamps so it could fit the 70mm wide type 2 vice I’d bought recently.

My earlier attempts to clamp the vice down on two points failed when the bolts rattled loose and the whole thing started being dragged back and forth across the table by the milling cutter. I decided was going to require at least four points of attachment to work, and these neat little clamps looked just the right shape — except for the problem of being slightly too tall.

(That current configuration in the picture was an idea Andy came up with at the last minute when trying to solve this problem.)

Andy had tried to skim them down on his lathe and told me that the metal was too hard. But I was determined to prove that anything could be done if you took little enough cuts. In this case it was steps of 0.1mm per layer and 0.5mm across

At 8000rpm there were sparks. These didn’t happen at 6000rpm. I was running with a 5mm 2fluke flat bottomed tiain-coated carbide tool. Furthermore, the conventional milling sounded marginally less nasty than the climb milling passes. I’m surprised nothing broke, though I don’t have the experience to tell whether a tool has worn out or not.

The result was pretty crap. Instead of performing some clean cutting, it seems like some of the metal was simply bashed flat and pushed out to form a lip around the face.
flatcut
I didn’t know that metal would have the propensity to produce this result when undergoing milling.

It’s not a factor accounted for any software I’ve heard of.

I’ve written many algorithms that detect the horizontal flat faces of a part and create toolpaths to skim them out, but no one has ever requested a subsequent pass just below each open edge to clean off the burr left over.

Sadly, there won’t be any more machining for at least six weeks as I’ll be in a rainy campsite in Austria waiting for the chance to fly. At least this will give me lots of time to try and write some useful code when I’m not washing pans or carrying rope and other provisions for the cavers.

Friday, June 17th, 2016 at 12:03 pm - - Whipping

I went to the International Festival for Business down at the Liverpool docks to see a presentation on the funding competition for 3D printing by InnovateUK yesterday.

I was quickly trapped in a dark room full of suits as the Government man painstakingly powerpointed his way through the process by which they were going to hand over several millions of pounds to the sorts of respectable businessmen who ultimately don’t give a damn if the technology can be made to work productively or not, because the underlying purpose of their job titles is to extract financial profits for themselves as the primary objective.

That is the very definition of a respectable businessman these days. It’s not ever defined as someone with the character to manage and inspire the teams of technologists who would have the capability to deliver the technology, or a preparedness to use finance in the service of these ends rather than as an excuse to impose inefficient and ineffective research and development methods onto any program they control.

Back in the old days when the Government wanted some new technology developed, like nuclear weapons, space travel or machine tools, people sought out and spoke to the engineers who were ultimately going to have to do the job, and then designed programs around the necessity of organizing these engineers to get it done as efficiently as possible.

If their one idea is that people like me have to be subserviently employed under a contract to deliver closed source software for the know-nothing suits they’ve deliberately empowered to curate this technology by virtue of proving them the grants, then it’s going to be a disappointment.

I walked out to the main hall where FW de Klerk was being introduced prior to his speech.

deklerk
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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.

tusker1

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.)

tusker2
Bit blurry, but there’s a dogfish swimming past Becka

tusker3
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.
mwnt

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.

Friday, May 27th, 2016 at 12:07 pm - - Flightlogger

The datalogger is fitted to the right hand upright of the control frame. According to my shoddy measurements the upright is 176cm long and the basbar is 138cm long. There are two wires from the corners of the control frame to a point on the keel 151cm forward, each of length 206cm. And there are another two wires to a point on the keel 80cm backward, each of length 205cm.

This seems to add up to a vector of (69.0, 42.06344442205491, -156.2492943010685) from the top of the control frame to one corner of the base bar, which is the alignment of the datalogger and its BNO055 orientation sensor strapped to the upright.

I definitely don’t have time for a complete blog record of this, and a lot of it isn’t working, even though I’ve spent no end of time hacking on things, but if I plot the logger vectors that go backwards and perpendicular to the upright on the gps track, I get this picture:

keelorientation

For scale, the red lines are 11m long and the plot rate is 3x on the 100Hz samples, so there are 33 of those lines per 1second of motion.

It’s reasonably smooth and consistent, unlike the accelerometer values, which I think represent a lot of vibrations in the system, if the creaking wicker chair-like noise on the gopro soundtrack is anything to go by. It’s about right, if you think of the airspeed being in line with the keel of the glider (which it is probably not, because of the yawing and side-slipping in turns).

I nearly bought a sonic anemometer second hand off ebay last week, but missed it. I’ve got an alert watch on a new one and have designs on fitting one to the top of the kingpost where it is out of the way and least likely to get damaged by flying into a hedge or the ground.

Regarding the kinematics of the system, every part of the flight is the same as everything else, so I can strip out the simpler bits to see if there is a relationship. In particular, this is a plot that claims to be 10 second long sections of the flight where the bank angle is less than 3degrees.

nobanksections

This doesn’t fit too well, and I can explain it that the calibration value on the device was at 1 out of 3 for most of the flight, in spite of starting off on the ground at 3/3, so it’s telling me it got it wrong.

Anyway, it’s straight enough to move on to this complex plot of some of those flight sections:

pitchsections

Time goes from left to right of about 10 to 20 seconds. The following traces have been displaced close to the zero horizontal white line so you can see their correlations, if any. Green is pitch angle, Yellow is smoothed acceleration in forward direction (approx because it’s not aligned with gravity yet), Red is airspeed, and White is differentiation of windspeed.

What I would hope for is a delayed correlation between pitch (green) and airspeed (red). If you push the nose up and hold it there, the glider will slow down, and then fly at a slower speed. If you pull the bar in and hold it there, the glider will speed up and then fly at a constant higher speed. But of course you’re moving the bar all the time. But you can almost convince yourself of the response; the green line goes down, and the windspeed then starts to rise, and vice versa.

This should be built this into a kinematic model of control and response. It would actually also align with the barometric reading, where the sink rate goes up with a higher speed, so it’s quite 2 dimensional in the vertical plane, with energy equations.

The other correlation should be between the forward acceleration and the derivative of the airspeed. Both the airspeed signals and the acceleration signals are quite full of noise, so they needed to be smoothed (I think I’ve done this incompetently here, but that’s for another fortnight of coding).

Here you would expect a direct correlation in still air, because if the accelerometer says I am accelerating at 1metre per second per second, then over the course of 2 seconds my absolute velocity will increase by 2 metres per second. And, if the air is still, then my measured air speed should also increase by 2 metres per second.

So these two ought to be scaled the same. Except the smoothing flattens out all the humps and troughs, so you really can’t tell what the absolute value of anything is from this anymore.

Some of the bumps seem to line up, but this is not adequate for a kinematic model.

The numbers get hairier and hairier as I try to approach something useful. And that useful thing would be to separate the absolute motion into that which is due to my control and the flight characteristics of the glider, and that which is due to the underlying wind speed and direction.

Accordingly, I should be doing lots of boring flights in completely still air at the start of the day with a working logger where everything is calibrated, rather than having lots of fun in thermic air. This is a job to do in Austria where the hills are high and I should have hours and hours in the campsite not coding on other things.

This work just takes so much time and has hit so many technical failures already that I doubt it could be done by someone who is answerable to a boss.

Wednesday, May 25th, 2016 at 1:05 pm - - Machining 1 Comment »

You know those clamps for the vice I was so pleased about fitting?

Well, they slipped out while milling metal due to all the vibrations during helixing.
loosevice

This just after I’d spent all afternoon compensating for the rotational position of the vice to withing 0.04mm across 50mm of its width by probing a piece of metal in the jaws wrapped in a piece of wax paper to electrically isolate it from the vice.

Bog! That’s ruined my day.

And the weekend is going to be rubbish, waiting in a tiny cold tent in Yorkshire for the fog to clear.

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.

tailbridge

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:
dunfellrasp
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.
mallerhail

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.

Tuesday, May 17th, 2016 at 4:22 pm - - Whipping

I met my first Leave Europe supporter yesterday, but didn’t have enough time to quiz them. But they referred me to Boris Johnson’s speech in Manchester as an explanation.

I listened to it all.

Boris banged on about those nasty EU regulations infiltrating every part of the nation:

“They can’t tell us what sort of trains we can run, can they?

“Oh yes they can!

“Oh yes they can!

“The EU Commission told us that by 10 Nov 2018 we must create a rail freight corridor to Glasgow and Felixstowe, which means that Network Rail can be legally obliged to accept rail freight trains in place of passenger trains.

“Of course our excellent transport minister spotted this insanity, with the west coast main line full to capacity. If we had more freight trains, fewer passenger trains, there would me more overcrowding and higher fares. So he wrote a fierce letter to the Commission complaining that they were circumventing requirements, bending the rules, and of competence creep aka sticking their nose into something that wasn’t their business. But the Commission told him to ‘go and jump in a lake.’

“So we took them to the European Court of Justice, and what did the Court of Justice say? They told us ‘allez vous plonger dans un lac.’ They ruled on that occasion as they have done in 80 per cent of the cases in which Britain has been involved – they rules against us.”

Now these are the days when the world is interconnected, and we have a Channel Tunnel, and roads that are utterly chockablock with a hundred thousand fat diesel trucks that can freely drive onto the motorways in enormous numbers.

In the meantime it’s practically impossible to arrange for a zero-carbon electric train to haul heavy steel products direct from the steel mills on the Clyde to the construction sites in Barcelona because of the amazing national railway bureaucracies along the way.

It takes years of painstaking systematic work to identify and address these problems, like those articulated in a Select Committee report from 2005:

Many of our witnesses told us that getting rail freight through France was very difficult. The significance of this problem is greater because France’s geographical position means that international rail freight to and from Great Britain and the Iberian Peninsula travels through France. We were therefore encouraged by Mr Hilbrecht’s confirmation that Europorte 2, a subsidiary of Eurotunnel, had received a licence and a safety certificate to operate in France…

The French two-part tariff system was also said to be a particular barrier to open access and fair competition within France. Mr Hilbrecht was happy “to say that we have achieved agreement with France . . . . They agree that it (the two-part tariff system) should be changed”. Unfortunately the French government claim that because of the public service contracts with regions they cannot do so before 1 January 2006. This two-part tariff system needs to be abolished. We hope that the Commission will ensure that the French government abolish it as soon as possible.

The last problem that we identified is the least tangible, but is nevertheless an important challenge facing the rail freight industry. The evidence we received led us to believe that the rail industry in general, and in particular the rail infrastructure managers, have inadequate incentives to win new traffic. We recognise that, for political reasons, rail passengers are given priority over the movement of rail freight. This appears to have resulted in an institutional framework within the rail industry in which there is little incentive to increase and improve rail freight.

Whatever the cause of this lack of commercialism and competitive performance, it has to be overcome if the rail freight industry is to revive and achieve its potential.

But Boris doesn’t give a toss about this if he can make people laugh at his stupid jokes.

He’ll say all EU directives and ECJ rulings are about Brussels bureaucrats meddling in everything with their crappy regulations, when these ones are about unpicking the thicket of stultifying regulations and prohibitive monopoly rules that make it impossible run trains across national borders.

You have to pass laws to repeal laws, and fight hard to get rid of bureaucracy.

Anti-democratic? Never mind that each one of these directives is examined, amended and passed by a European Parliament that gets elected every five years where every vote counts equally, so that when the Green Party gets 6.7% of the votes, it gets 6.7% of the seats — unlike in the utterly screwed up system in the UK that gives disproportionate representative power to tosswits like Boris to tell us like it isn’t.

Yes, I mentioned that steel industry, the jewel in the crown of Britain’s awe-inspiring industrial revolution of the 19th century. You remember how a private corporation in one of our former British empire colonies bought it in its entirety for small change ten years ago and then shut the whole thing down last week? How humiliating is that?

So much for the Commonwealth Dream, eh? I don’t see Britain owning any comparable assets in foreign lands, other than a few seedy tax havens.

This should have been a seminal moment in our nation’s self-image.

But it isn’t because our political feelings have become pathologically detached from reality.

Apparently the EU tried to save the steel industry by putting tariffs on Chinese impots, but this effort was blocked by the UK government because our policy is to toady up to everything the Chinese want no matter what the cost.

That’s because the country that built the first commercial nuclear power station in the world in 1956 needs that Chinese finance to pay French engineers to consider building a new one — at a cost not quite as high as the International Space Station.

It’s not going to fly. And it doesn’t include the cost of taking it down, let alone in time for the sea levels to rise and wash the resulting radioactive sludge inland to Bristol and all along the North Devon coast with the tides.

Isn’t it curious the highest profile proponents of the Britain to Leave Europe are also climate change denialists? Once you have one delusion of supremacy, it’s easy to get more.

As Professor Danny Dorling pointed out:

The UK is not a typical country in Europe. If we were more typical I would have more patience with those who suggest that we could leave and our lives would improve. But in many ways we’re a poorly performing affluent country. This poor performance has little to do with the EU, and a lot to do with us, and our legacy of having had an Empire. From the Suez crisis right through to the Panama papers, there’s a series of embarrassments that have occurred and, in a way, this referendum is just another one of those embarrassments.

Some people have a fantasy (enjoyed by the majority of the Brexit group, particularly the Cabinet ministers) that if we were to leave we would become ‘Great’ again. We could become the richest country in the world again, and our EU membership is why we are not ‘Great’.

And, so, because a lot of sensible people are sick and tired of arguing with these total idiots, we feel like letting them have what they desire, and getting us out of Europe. And then the Europeans are not going to help us with driving our trains, cars, people, money, goods or anything else across our the borders and into their lands. Things will pretty quickly stop working and go south.

And these politicians who sold us this knackered bill of goods will absolutely own it. We’re going to have to finally learn the hard way how Not-Great we are. It’ll be good in the long run — if there was a long run — for us to have a more realistic perspective about who we are. After all, losing their big wars seems to have done a power of good to the standard of living of the people in Germany and Japan.

In the end none of this matters one little bit. We are arguing about these petty matters when we should be freaked out by the fact that the near-term human extinction has become inevitable.

At some point everyone will learn that we are nothing more than ten billion monkeys farting around on one lonely planet with made-up borders. We’ve used our big brains just enough to fuck things up royally, but we just cannot be arsed to turn it up another notch to avert disaster, can we?

Thursday, May 12th, 2016 at 5:04 pm - - Machining

I have actually been doing some machining at long last, having purchased a 130-040-01900 Precision Tool Vice Type 2 – 70mm wide vice, which feels reassuringly solid, square and metal for the entirely reasonable price of £56 — given that this is about what I’ll need to pay for a single tapered cutter when I get onto that project.

clampthinning
First problem was that the hold down clamps were a bit too wide to fit into the groove comfortably, so I milled them down by about 1.5mm. There had been a worry that these would be hardened steel, so I tested one by cutting a groove into it with a hacksaw. Of course the clamps are going to be soft steel. If it was hard metal it would be liable to make horrible marks in your work-piece.

looseclamp
Then I tried squaring off a bit of model board. This is what happens when you forget to tighten up the vice and the cutter lifts and ploughs through it before tossing it off the table.

A bit more practice, some work on toolpaths, more tools, the procurement of some pieces of metal, and I’ll be ready for business. Just in time for the holidays.

Monday, May 9th, 2016 at 4:49 pm - - Flightlogger

I made an interesting mistake during my flight over Merthyr which began in very rough air. My radio was charged and working, which meant I had an external source of misinformation to confuse me, that I did not have on my excellent flight from Builth Wells three days before.

One of the things I thought I overheard was that the thermals were tracking southeast in spite of the wind on the hill coming from due west. This suspect information lodged into my brain, so that when I finally got a good thermal I began tracking to the SE instead of due East with the wind, and fell out of it, and landed an embarrassing 5km away to the SE on a smooth bit of grassland feeling rather unhappy with myself.

Still, nothing important broken, except my ego. The data came out good, with the following temperature track vs altitude, where horizontal lines are degC from 0, vertical lines are 100m (topping at 1200m on the right), and green data points are during the climb, with red for the descent.

merthyralttmp

Potentially this means in such a strong thermal the temperature was one degC higher than the surrounding air, with brief drops in the readings in the moments where I fell out of the thermal. The climb rate up to 1000m was between 2 and 4m/s, but above that it became less than 1m/s — coinciding with period the temperature differential had decreased.

The thermal temperature is going to be all mixed up with rising air and surrounding air as I go in and out of the core, but it seems to have a pretty constant trend. The non-thermal air (encountered when I utterly lost the thermal) seems to be completely constant between 1000m and 1100m, which would account for the decline in thermal strength (according to theory) and at 1050m only differed by 0.3degrees.

Unfortunately, with only one thermal in the flight to derive the data from, the pattern is not definite. I think I should do something more serious with the temperature sensor, like fit a cowl over it to protect it from sunlight while directing the full flow of the wind across the device. It cannot take more than seconds to equalize. I ought to revisit my vacuum cleaner and hairdrier experiments.
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