Tuesday, November 6th, 2018 at 6:51 pm - - Hang-glide

Quite a lot of work in the last week (especially at the weekend) reading a big book called Tailless Aircraft: Their Design and Characteristics, published 1994, translated from German.

The blurb on the inside cover reads:

The authors are uniquely placed to compile the first practical and comprehensive treatment of this fascinating branch of aeronautics. They have for many years collaborated on the practical and theoretical development of flying wings, applying themselves to sailplanes and powered designs ranging from models to full-size craft. In 1988, together with Klaus R, they received the “Berblinger Award” from the City of Ulm for their investivation into the design for an optimum tailless hangglider.

What the heck is the “Berblinger Award”?

The winner of the 100,000 Euro Berblinger Flight Competition was declared on Sunday 17 April, in the Ulm town hall. In all, 36 participants competed for the prize, which focussed on the use of innovative, ecological and resource-saving technologies. Of the 36 applications received, 24 aircraft were initially admitted to the competition. 13 aircraft started successfully; due to insufficient financial backing, technical difficulties or the absence of the appropriate flying licenses the remaining competitors were not able to take part in the practical phases of the competition, which was carried out at the AERO global for general aviation, in Friedrichshafen. Eight participants successfully completed the exercise of flying from Friedrichshafen to Ulm.

Two anniversaries were celebrated with an extensive programme of events during this weekend in Friedrichsau Park and the Adlerbastei: 200 years ago, King Friedrich 1st gave the Friedrichsau Park to the people of Ulm. In honour of his visit, Berblinger performed his attempt to fly across the Danube.

Who the heck is Albrecht Berblinger?

One of Berblinger’s inventions was what appears to be a hang gliderKing Frederick I of Württemberg became interested in his work and sponsored him with 20 Louis. He tried to demonstrate the glider on the evening of 30 May 1811 in the presence of the king, his three sons and the crown prince of Bavaria. The king and a large number of citizens waited for the flight but Berblinger cancelled it, claiming that his glider was damaged. The next day he made a second attempt. The King had left by this time, but his brother Duke Heinrich and the princes stayed to watch. Berblinger waited so long for a good wind that a policeman finally gave him a push and Berblinger fell into the Donau (Danube).

It sounds like the experience on some of my takeoffs.

But enough of that rabbit-hole.

I’ve been attempting to replicate some of these graphs and diagrams from the book, like these ones:

After many days and many attempts, I got to this matching version:

This was not helped by the mistake in Formula (2.7.5)!

I could not replicate the other four lines for the “neutral point” (some details about dc_l/d(alpha) has been left out).

In the process of this I have wasted no pencil and paper, and proved the power of SymPy, which I think all mathematics should be written using.

The details are all on the Horten sailplanes Jupyter notebook. It’s probably a good thing I don’t have the technology to inline mathematics into this blog.

Wednesday, October 31st, 2018 at 12:24 pm - - Kayak Dive

A quick weekend to take advantage of Becka’s trip to Southampton University to work as an examiner. Unfortunately the university library was card controlled, so I hung out in the Burgess Road Public Library skimming through a tourist book about the Isle of Wight (containing no useful information) and then reading part of a Douglas Adams book.

We drove over on the ferry on Friday afternoon to stay with an old hang-gliding buddy, who is now the last hangie on the island. This, down from a time when, during the 1980s and 1990s, one of the largest hang-glider manufactures in the world was in operation.

It was too windy for that game, and blowing from the north, so we took our kayaks, went out of Freshwater Bay and paddled to The Needles.

It seemed too windy and scary to get out to the far needle, so we got back and gave our friend a trip round the bay, then walked up to the battery to see the stunning white cliffs from another angle. It was cold and windy.

On Sunday we took the cycle trail from Newport to Sandown, emptied all our tuppences into a machine, and cycled back again, pumping up the tyres every couple miles due to a slow puncture.

I’ve been doing my best to get through the book Tailless Aircraft in theory and practice that I nicked from my friend’s bookshelf on the way out. More on this later. The mathematics in it feels a bit shoddy, which might be why I’ve never got through such engineering books before. Foundational assumptions, such as the optimality of the elliptical lift distribution, are stated in passing because the practitioners have so internalized them they don’t even notice. It’s as basic to the equations as the conventions of using (x,y,z) for the axes and t for time. Also, these engineering guys will divide anything by anything just to get a dimensionless constant.

Then on Monday I put it in practice by driving over to Treak Hill in the peak district and bombing out to the bottom landing field, while everyone else had a lovely time flying all round Mam Tour. (The airforce glider is a two person glider that also went down, because it’s quite heavy. I packed it up while the pilot went up for a proper fly.)

Maybe tomorrow.

Tuesday, October 23rd, 2018 at 9:51 am - - Whipping

This comes from three pages at the start of Chapter 21 “What Is Money For?” from the 1926 book Today and Tomorrow by Henry Ford and Samuel Crowther.

I have photographed and transcribed it, and have nothing better to add to what he said, except to observe that not one thing has changed in a hundred years, and that you don’t find business experts talking like this in modern times — probably due to the long-term re-education process by the finance industry and their deep conflicts of interest combined with a total lack of intellect.

The most common error of confusing money and business comes about through the operations of the stock market. And especially through regarding the prices on the exchange as the “barometer of business.” People are led to conclude that business is good if there is a lively gambling upward in stocks, and bad if the gamblers happen to be forcing stock prices down.

The stock market as such has nothing to do with business. It has nothing to do with quality of the article which is manufactured, nothing to do with the output, nothing to do with the marketing, it does not even increase or decrease the amount of capital used in the business. It is just a little show on the side.

It has very little to do with dividends. A large part of trading in stocks is without reference to dividends. Except with the sober investing class, the dividend is of little consequence; at least, it is not the main objective. Some of the most “active” stocks do not pay dividends. The profits sought from stock trading have no relation to the earnings of industry by the production of goods. The price of a stock often depends wholly on how many people want to buy the shares that are for sale.

The state of the stock market may make a deal of difference to the officers and directors of a company if they are dabbling in the stocks and trying to make money out of the securities of the company instead of out of its service. These stock-market companies are of little consequence: they flicker and die out. But they do serve to convince people that the stock market has something to do with business, whereas, if not a single share of stock changed hands, it would make no difference to American business. And if every share of stock changed hands tomorrow, industry would not have a cent more or a cent less capital to work with.

The whole stock activity, therefore, is on par with organized baseball, so far as the fundamental interests of business are concerned: it is a side show, unrelated to the basic principles of business and supplying none of the necessities of business. It has only a spasmodic and accidental relation to values. If the extreme speculative element were removed, the natural buying and selling of stocks would be but a mere side line of banking.

We further hold, however, that strings on a business held by those not engaged in it are hindrances, because often it compels the business to become a money-maker instead of a commodity-maker. When the chief function of any industry is to produce dividends rather than goods for use, the emphasis is fundamentally wrong. The face of the business is bowed toward the stockholder and not toward the consumer, and this means the denial of the primary purpose of industry.

The absentee stockholder is one of the principal, though concealed, items in the unnecessary and preventable costs of living.

All this is defended, of course, by the statement that stock represents a contribution to enable industry to function. The story, however, is not so simply told. When preferred stock, for example, becomes a burden on production, the benefits of industry become private instead of public, and this cannot be defended on any terms. There comes to mind an instance where a charge of fifty dollars was added to the cost of an article to meet the demands of stockholders. In another case one hundred and twenty-five dollars per article was added for the same reason.

Industry is not money — it is made up of ideas, labour, and management, and the natural expression of these is not dividends, but utility, quality, and availability. Money is not the source of any of these qualities, though these qualities are the most frequent sources of money. Any business is better off when its money comes from the buyers of its product. Such money is not a charge on the business or on the public. Money that enters in any other way becomes a charge on the business. Its main interest is its own increase, and the public never gets through paying on the original investment.

But stock speculation is not without value — some really good men lose at it and in consequence are compelled to go to work. The stock habit takes too many men’s minds off their legitimate business. Anything that drives them back to their proper sphere is a benefit. Wealth is not increased by stock activity; at best, it only changes hands. Wealth is not created; it is but a score in a game. I was once quoted as saying that the stock market was a good thing for business. The reporter omitted my reason — “because it drives so many men back to legitimate business by breaking them.”

Monday, October 22nd, 2018 at 4:33 pm - - Kayak Dive

Still not getting out much at all. Mostly just doing work (not paid of course). The time seems to go somewhere; still not sure what I’m getting done, if anything. I’m not even generating much 3D printing scrap, like I used to every week.

Anyways, we got tempted out on a kayak dive last Saturday, which went very well.

However, the point of the dive was to demonstrate kayak diving to the duttons divers, who do training in their own Vivian Quarry and run dive boat trips out to Puffin Island. We had their timetable, and they were about an hour and a half late (they were supposed to be in the water at 11am). Sometime after 12 we gave up waiting and did a dive anyway, in the drop-off on the north side of the island, in the stiff along-shore breeze. It was terrible timing. They then came by and dived without us while we were underwater. Ho hum. So I’ve failed to spread the goodness of kayak diving, as I’d hoped, because we didn’t faff enough.

Paddling back was a bit of a slog against the wind, almost making no progress across the sound past Perch Rock. Then, back on the mainland, we gave up trying to paddle up the coast to where our car was parked, landed, send Becka to get the car and bring it back, while paying the £3 car parking at the end.

Then it was back for lunch and apple pie with our friend in Menai Bridge, and then off to meet people at Vivian Quarry a couple hours later once they’d finally got off the boat and finished faffing. It was cold. We drove home, dropped me off, and Becka went off to Yorkshire to dig gravel while I washed up the gear and did another day of unaccountable work. Today I skipped a chance to go flying to watch Fahrenheit_11/9 at its single screening, which Becka thought was a bit heavy for daytime entertainment. I still feel guilty at not having gone to the People’s Vote march.

Monday, October 1st, 2018 at 3:46 pm - - University

I was over at The Hague last week for Sensible Code taking the overnight ferry instead of burning the planet with the so-cheap-and-convenient.

The highlight of the trip was a visit to RevSpace, probably the tidiest hackerspace in the world. As I cycled back to my hostel at 1am, I was wracked by the guilt that I’d walked out on two empty cans of diet coke and some crumbs at my desk space. It’s quite a nocturnal place, and I had to quickly run away before I accidentally stayed there till the sun came up.

I spent most of the evening trading tech with WJ who warmed up when I showed him how our hackspace in Liverpool manages its affairs through Github issues, and he couldn’t believe that we had things like Issue 807: “Replace the toilet seats” in public on there since last May. RevSpace doesn’t have a somebody-should/work-to-be-done list because all work has already been done as soon as somebody notices it.


Sunday, September 16th, 2018 at 2:33 pm - - Flightlogger

Don’t know why, but I’ve got lazy with the blog. Probably due to use of twitter/goatchurch for quickly reporting things, which then lets me get on with what I’m doing.

Also, code gets done at github/goatchurchprime and github/Future-Hangglider.

Then I was in France and, after a couple of crashes on takeoff which took out my higher performance glider during a training week, I won the sports class on my old Sport2 that someone had driven out from Liverpool at short notice.

There continues to be a good deal of wholly ineffective data-logging from hang-gliders and stuff like that. I’ve been trying to learn to do something with FreeCAD, Blender, and Dales. It seems impossible to catch up, even if you don’t do anything new. And you’ve got to catch up or you can’t do anything new.

I still feel good watching this video Becka took in France during the competition being talked off the hill by the lovely JB on what became my best flight of the year. The eventual destination was beyond the hills on the horizon to my left. You can see my mind focussing.

Friday, July 20th, 2018 at 10:54 am - - Whipping

To me, your justification for Brexit seems incoherent and illogical.

Your basic premise — in common with a lot of superficially thoughtful criticism — was that the EEC began as a treaty to regulate trade and harmonize regulations, and has then metamorphised into a superstate taking on powers and imposing new laws far beyond this remit. The people are not ready for this.

You gave as an example of super-state over-reaching powers, something from Intellectual Property law — your area of interest. The example was Copyright Extension, which you claimed — correctly — was not about harmonizing some regulation across Europe, but of extending it far beyond what anyone had before.

Really? This is your example?

But we’ll go with it.

Regulations have to change and move forwards with the times, and the point of European system is to make these changes in harmony across the whole of Europe at the same time.

Otherwise, your definition of “Regulatory Harmonization” implies that EU can only impose regulations onto the UK that had existed elsewhere in the EU prior to 1973.

Put into that context, it’s easy to see why the early years of the EEC would be mostly about harmonization of regulations, while the later years became more about drafting new regulations when those pre-1973 regulations grew out of date through processes we can call time passing. To expect otherwise is illogical, Captain.

But, on the subject of Intellectual Property, let’s look at the pragmatic situation. We all know where the policies of successive UK Governments on this issue lie. For sure, if we had not been part of the EU we would have experienced Copyright Extension and Software Patents good and hard since 1998, via a trade treaty with the US.

And good luck with lobbying our supposedly more democratic UK MPs to vote against Software Patents, as we did with European MEPs. They will either not understand it, or agree that it’s harmful but consider it something well worth selling out in order to get a better trade deal with the US. It’s give and take in the negotiations, you see, and we are a small country who don’t get to impose our will on an international super-power. Anyway, Software Developers already do well enough to make a living on the job market; we can trade them to protect our sheep farmers.

Ah, but there’s Taking Back Control.

My turn for an example.

After Brexit, the French police can Take Back Control over who is allowed to drive on the French highways. So if I cross the Channel by car, the French police can arrest me for not having a valid MoT on my car, the lack of which means it’s officially unsafe to drive and could kill someone. Bad idea.

Fortunately, there’s an international court called the ECJ to enforce the treaty/contract between the French and UK Governments that says my MoT certificate for my car issued by the UK Government is as good as the French paperwork.

Now, the French Government can only sign such an agreement to respect our MoT certificates if they have the assurance that our safety and inspection standards are up to scratch — both in terms of the quality of the regulations and in their enforcement.

We have to allow the French Government to potentially take the UK Government to court if they think the UK Government is not doing a good enough job of prosecuting cowboy garage operators who are issuing MoTs to unsafe cars that could then kill people on French motorways.

Otherwise, without the ability to seek redress in court, the French would just have to ban all cars with UK MoTs until the UK cleaned up its act.

However, in such a dispute, it is possible that the French are simply wrong and are being too picky about their standards, and are deliberately making safety requirements that just so happen disadvantage UK cars. So we’d like this matter to be considered in a Competent Court that values its reputation for impartiality — not just some ad-hoc tribunal made up of three dudes deep into conflicts of interest appointed by both sides that has to come up with an answer in 30 days or else.

And we’d like the decision to be worked out and enforced justly, without threats, organized disinformation in the Press, counter-measures and political grand-standing hanging over it — which is what happens when you don’t have a framework of functioning law that punishes such disruptive activities.

This story about the MoTs and car safety across borders generalizes to every other field of regulatory cooperation. Basically, if you plumb your toilet into the main sewerage system instead of to a hole in your back garden, you give up control over how many tampons you can flush down it. What was so important about having Control again?

And finally, you suggested a time-frame of five years. It could be bad and painful during the transition period, but we need to hold our nerves while we take back control, until it all works out.

This time-frame, quite frankly, is pulled out of someone’s arse. No basis on anything. Here’s one way to make a number. Trade treaties take about ten years to negotiate, so why not say ten years, plus another five to account for the fact that no one in the UK Government has negotiated one in 45 years. Does 15 years of chaos and closed borders feel worth it?

I mean, I’ve got an estimate for the time horizon for how long this takes to work out. But it’s not expressed in years; it’s the length of time it takes for enough of the Brexiteers to come to terms with the fact that their slogans of Sovereignty, Control and so-called Democracy (with an electoral system that does worse than if you picked 650 citizens for Parliament completely at random) are totally vacuous.

Maybe it takes one month. Maybe it’s fifty years. Nobody knows yet. How long can this society carry on with an unbroken layer of denial and mendacity at the top when the shit gets real?

I’ll check back with you in about year after it hits the fan. The gradient of the learning curve will suggest a more numerical estimate. By then there will be four-and-a-half out of the quoted five years remaining for things to get sane. My theory is that because it’ll actually be happening to us, and isn’t some foreign game like a war, the Friedman Unit trick of always quoting five years in the future from now won’t work.

The main consequence of taking Control is that we must take the Blame.

Tuesday, July 3rd, 2018 at 7:50 pm - - Flightlogger, Hang-glide

We had a go, where I rigged my U2 hang-glider in the front garden with the VG full on to make it rigid, and then standing it on its nose so that JR could take lots of nice high definition photos of it from a variety of angles with a proper camera with a big lens.

The Agisoft Photoscan thing initially got it right, with a good looking 3D image:

But then I started doing things with the point scan — in particular finding its symmetry so as to compare the left wing with the right wing.

The code is here.

Basically, I loaded the 9653216 points from the csv file with this one Python command:

k = pandas.read_csv("hg1a1b.txt", sep=" ", names=["x","y","z","r","g","b","nx","ny","nz"])

And then worked out that I could perform vector calculations on the columns of coordinates, like this

# Reflect about the plane through x=2 parallel to the YZ plane
mv = pandas.Series({"x":2, "y":0, "z":0})
mvsq = sum(mv**2) # (scalar)
mvfac = (k.x*mv.x + k.y*mv.y + k.z*mv.z)*2/mvsq - 2  # 9million value column
kmirr = pandas.DataFrame({"x":k.x-mv.x*mvfac, "y":k.y-mv.y*mvfac, "z":k.z-mv.z*mvfac})

The alternative more memory efficient calculation method, performed row by row runs many, many times slower:

kmirr = k.apply(lambda R:R[["x","y","z"]] - mv*((R.x*mv.x+R.y*mv.y+R.z*mv.z)*2/mvsq - 2), axis=1)

There’s something curious about this column mathematics and how it applies to computational geometry.

In any case, have produced an animation melting through from one wing tip to the other, like so:

It seems that one wing is much fatter in depth than the other.

I think this is a photogrammetry error in its understanding of how far apart to put both sides of the wing. The gap at the leading edge on the fatter wing gives it away.

As is my observation in freeform CAD/CAM: you can get away with a lot of deviation from the required surface because no one can tell when it’s wrong. They can measure the flatness of the square edges, but errors in the middle of the freeform surface (so long as they are smooth) pass without notice. I suspect a lot of photogrammetry works on that principle. It’s only when we scanned something with two sides that was supposed to be symmetrical could I tell there was a big a problem.

(To be fair, the Agisoft failed when we reran it to get a better fit. It is better to

Well, so much for that. I had hoped I’d have something good enough to trace up and enter into XFLR5 as a series of contours, but it’s not quite.

However, I should just make up a series of contours based on this anyway (since it has things like the washout/twist approaching the wingtips) so that when we get good data (eg from a laser scanner) we are all ready for it.

Tuesday, July 3rd, 2018 at 5:50 pm - - Kayak Dive

# date site depth divetime
1 25 June 12:00 marine park pinnacle 20.5m 47 minutes
2 25 June 14:42 Citrine (wreck) 15.4m 52 minutes
3 26 June 10:41 Sugarloaf caves 12.7m 61 minutes
4 26 June 16:42 Thracian (wreck) 32.7m 29 minutes
5 27 June 11:00 The puddle 18.1m 58 minutes
6 27 June 17:26 Burroo 21.3m 54 minutes
7 27 June 20:14 Bay near Burroo 18.7m 56 minutes
8 28 June 11:30 Gibdale Bay 22.4m 47 minutes
9 28 June 14:24 St Mary’s Ledges 19.8m 57 minutes
10 28 June 22:19 Port Erin 11.3m 63 minutes
11 29 June 11:04 Thousla rock (wreck) 20.8m 50 minutes
12 29 June 14:04 Sugarloaf caves 11.0m 57 minutes
13 29 June 19:19 Spanish head drift 21.6m 40 minutes

Really very much good diving stuff with Discover Diving on the Isle of Man last week. We went over loaded up on our bikes (can’t find the pics) on a trip with LUSAC from the ferry terminal about a mile away from our doorstep. My logbook records over 11 hours underwater in 5 days of luxurious cold water diving.

It was insanely hot and the sea was mirror flat most of the days. We stayed on for an extra two days for a cycle to Peel and back to Douglas, though actually we spent most of those days sleeping to escape from the heat.

We saw some amazing sights, like this bird swimming underwater:

That was at the end of the dive in the Sugarloaf Caves, which in every way (except the kayaking) outmatched our cavern dive on the LLeyn a couple of weeks before.

As usual, we had problems with the fact that air goes only upwards when you try to fill a blob. “No,” I shook my head.

We got better at deploying it later in the week. Here’s a dive to the anchor chain and half a giant anchor on the Thracian. When you release the blob to the surface you realize just how deep 32 metres actually is.

On the night dive we annoyed an octopus who was trying to do its hunting in the dark.

Our final dive was a fast(-ish) 2 knot drift with the current from Spanish Head which left us feeling happy, going with the flow.

I don’t have a lot of time to write this up. Maybe there will be some other vids later on when I’ve gone through them a bit more. (Most are terrible.)

In the meantime, here’s me in black on the deep dark wreck, startled by someone else’s light.

Thursday, June 21st, 2018 at 11:31 am - - Cave, Kayak Dive

Last week we completed the unfinished business of properly kayak diving the underwater cave at Pen-y-Cil headland Aberdaron in Bardsey Sound in perfect conditions

Just look at these conditions:

We had 10 metre visibility, lots of air, and got a nice swim through with lots of crabs.

Even did the side cave too. As Becka’s neckseal had split, I dived the Glenocum wreck on my own on the way back. It was so relaxing.

On day two we did some (very cold) snorkeling off Criccieth looking for seagrass (didn’t find any pipefish).

On day three we were going to paddle around from Whistling Sands through Bardsey Sound, but decided that would be too scary, so we went and played in the overfalls by Nefyn. The waves looked huge when we were there, but don’t amount to much in the photos.

We got air fills at Tyn Rhos Diving which surprisingly still existed. And beforehand I visited my mum for one night in Machynlleth before driving up for a night in the campsite behind Eric Jones Cafe and meeting Becka off the bus in Tremadoc, after much protesting that I didn’t want to drive up and fetch her from Caernarfon ridiculously late in the night.