Something nerdy about Toggle Actions

You're free to copy this but please acknowledge the source.

What's his face Henry came up with the first really successful repeating rifle by using a toggle action, Winchester got into guns by manufacturing it and the rest is history...

Maxim received a bruised shoulder from firing a heavy calibre winchester and got to thinking about using recoil to operate the gun. With a telescoping stock and a lever mechanism connecting that to the gun's lever action, he succeeded.

He even got some military sales and Turkey had self loading rifles about the same time as Britain was adopting the Lee Metford and the US was still mostly equiped with trapdoor Springfields.

Maxim went on developing his ideas and developed a belt fed machinegun, with a toggle action...

He also patented all the other known automatic operating systems as well, but it was with the toggle action that he had most success.

Borchardt set about developing an automatic pistol, and appears to have looked to the most successful machineguns of the time for inspiration. His pistol had a toggle action...

George Luger and Hugo Borchardt set about turning the clumsy pistol into something more useable, who exactly did what bits is lost to history, Borchardt certainly got pissed off if anyone called the result a "luger". The important bit here is that the pistol had a toggle action...

What is so special about a toggle action?

Think of the compound linkage on a reloading press, It gives lots of leaverage at the top end of the ram travel, good for heavy sizing and swaging jobs, and fast movement of the ram lower down for quick operation where little leaverage is needed.

In a lever action rifle it does just the same thing, it provides lots of leaverage for primary extraction and provides fast bolt travel further back for fast cycling of the action, plus, when you take the toggle over centre, it works to lock the action, true it makes a long springy lock, not very good for supporting the heads of high pressure cases, but it will lock.

If you don't take the toggle over centre, it can be used as the basis for a delayed blowback action, like the .22 Erma luger look-alike pistols, the experimental Pederson rifle and the hideous Schwartzlose machineguns, which required oiled cartridges and had a recoil spring capable of killing a careless person trying to strip the gun.

A little diversion for a moment. Other designers of recoil operated machineguns for example Browning and Lahti, incorporated accelerators into their actions to harness some of the energy from the recoiling barrel and action and transfer that energy to the bolt to ensure positive extraction and cycling. in machineguns, that is also necessary to help operate belt feed mechanisms as well.

Looking at the operation of the Luger pistol, I forget the travel of the barrel and slide before unlocking commences, but it is sufficient to allow barrel pressure to drop.

Something very interesting happens then. Something that has been lost to most writers, but appears to have been all too obvious to Browning and Lahti.

The cam ramps at the back of the pistol frame ACCELERATE the toggle joint upwards, transfering the energy of the recoiling slide and barrel to the bolt, ensuring positive extraction and cycling.

When Lahti set about creating a more reliable pistol than the Luger for Finnish military use in Finnish winter temperatures, he discarded the Luger's complicated and malfunction prone trigger linkage and striker for a tried and tested conventional enclosed sear and hammer of impressive proportions. He also enclosed the bolt and locking mechanism, but, here is the important bit, he still needed to re-claim all that energy that would otherwise be wasted from the recoiling barrel and slide assembly, so he was forced to adopt a seperate accelerator.

How did other pistols with big slides attached to recoiling barrels manage to work?

I can't comment on the Bergman Bayard, because I don't know, but from looking at cut away sections of the Mauser '96 pistol, it appears to have unlocked after very little slide travel and to have used remaining gas pressure in the barrel to assist operation. This may account for some of the reputed fragility of this pistol and its' Spanish cousins, as unlocking with pressure still in the chamber puts a lot of stress on the locking surfaces (one of the reasons that guns like the MG42 and the G3 use rollers in their respective locking and delay mechanisms, to spread out the wear over a larger surface).

What about Pistols with Browning's slide?

They don't need an accelerator, as the recoiling barrel is very light and not much energy is lost by it just hitting the frame, and the main recoiling mass continues back to complete the full operating cycle. Browning type slides are cheaper to machine than the likes of Lugers, Lahtis and Mausers, so you can make more of them with the same value of machine tools and number of skilled workers.

Browning designs with the swinging link barrel connection, like the 1911, share the Mauser's problem with moving locking surfaces under pressure, and are therefore subject to wearing faster than toggle actioned guns, however later designs like the GP35 "Hi Power" use a fixed cam to allow free travel of the slide and barrel before locking begins and are therefore less subject to this problem.

What if Lahti had used a Browning slide with an enclosed hammer?

I think we'd all have one.

Comments

I've just found out that comments were set for members only. I've changed that, comments are open to all now.

Simple Ballistics

This is a follow on from a link at Alphecca to some comments about Varmint Ballistics

Current Gunzines are so much bull shite that the chances of a newcomer to shooting learning anything from them or finding references to any decent followup reading are close to zero, so here goes...

How a gun works

A gun uses heat energy stored in the powder to give the bullet energy. In this respect it is a heat engine, just like a steam engine, Automobile truck or ship engine, or a jet or rocket engine. Many of the analyses of these other engines work pretty well for guns. Go to your local public library or college library (not the magazine rack at the mall), and there should be some good references with all of the formulae and explanations.

Look especially at the pressure displacement graphs for engines (in steam engines these were called indicator diagrams. These were invented by James Watt, whose great discovery was not the steam engine (that was Newcomen) but what heat did inside an engine), and some of the ideal gas equations.

Geoffrey Kolbe at border barrels wrote and compiled an excellent ballistics handbook about 5 years ago. It is probably worth looking up his website to see if he has any left, or trying www.abebooks.com for a second hand copy.

Kinetic (movement) energy is half the mass of the object times its' velocity squared.
Therefore to double the velocity of a bullet you need 4 times the weight of powder to supply the energy.

The energy content of smokeless powders is pretty similar, weight for weight. (not volume for volume as pistol powders are porous or flattened to speed burning, as many pistol loads need to finish burning before the bullet leaves the case. with rifle loadings, some of the burning goes on up the barrel).

The efficiency of the cartridge bullet and barrel combination depends mostly on expansion ratio. (just like a car does, so a diesel with larger expansion ratio is able to turn more of the heat energy from the fuel into horse power turning the wheels, than a gasoline engine with lower expansion ratio is able to).

Each combination of case capacity versus bore volume and bullet weight has an optimum load.

This will use a powder of a given burning rate to prevent the pressures rising too high for the barrel to withstand.

Optimum barrel lengths for different loadings vary, for example the optimum, for a .22LR, is about 14 inches, beyond which the bullet begins to slow again as the gas pressure is lower beyond this point than the friction acting on the bullet.

The high thermal efficiency of a .22LR rifle is indicated (very, very approximately) by the quiet muzzle blast, most of that heat energy has gone into speeding the bullet and heating the barrel.

Compare that to a short barreled magnum rifle or pistol... Much of its energy from the powder is coming out of the barrel as flash and blast, not driving the bullet, but where high velocities with heavy bullets and a quick handling light gun are needed, there is little alternative.

Even for benchrest there is a trade off between short rigid barrels that give more stable shooting and longer and therefore whippier barrels that give more velocity and therefore less wind drift.

How to get more buck for your bang

There is some extra efficiency to be gained from:

short fat cases (better ignition as the powder is all close to the primer)

larger calibres (less cold bore area absorbing heat)

and sharp shoulder angles on the case (combustion taking place in the case not up a cold barrel)

Compare these to the means of getting more efficiency out of a diesel or gasoline engine... Higher compression ratios (more expansion) domed or pent combustion chambers as opposed to side valve combustion chambers or indirect injection diesels (less heat loss). Short stroke bores(less heat loss).

There is also some tinkering that can be done with powder. The gunwriters on the net site from Finland ( http://guns.connect.fi/gow/gunwriters.html ) says some very interesting things about cool burning powders (along with a lot of other interesting things about guns in general).

While scientists in Britain worked on a smokeless powder with exactly matched nitrocellulose and nitro glycerine contents for maximum heat value per grain (nitrocellulose burns to give excess carbon monoxide, tri nitro glycerine burns to give excess oxygen, put the two together and there is more heat energy to be had, this combination is called a Double base powder).

Mendeleyev (also spelled but mis pronounced as Mendeleev) the genius who came up with the periodic table of elements, and thus in chemistry ranks somewhere near to where Darwin does in biology, reasoned that including salts in the powder that would break down to give water or carbon dioxide, would cool the flame temperature, but, that the light gas molecules would be easier to accelerate up the barrel of the gun, so propellant effect would be the same.

Thus the Russians came up with an equally effective propellant that was a lot less aggressive to barrels and gave less heating during prolonged firing. (Cordite, as the British double base powder was called, was renowned for attacking the first couple of inches of rifling due to its' high flame temperature).

What happens to all that mass in the powder?

It becomes mass of hot gas that must be forced up the barrel behind the bullet. In other words, as charges get heavier, we have to devote more and more energy to propelling the gas itself, reckon on about half the weight of your powder charge being propelled along behind the bullet in the barrel.

When it pops out at the end, it is adding to recoil, the hotter and denser it is at that point, the more it will kick, bang and flash.

Recoil is momentum, which is mass times velocity, the faster that gas goes...

Now for something counter-intuitive (gun freaks are good at this sort of thing)

A big long posting by Boots Obermeyer over at Sniper country upsets the idea that reducing barrel friction will increase velocity.

Boots, who has probably forgotten more about guns than I will ever know, found that he was getting lower velocities (and I think lower pressures) with molybdenum disulphide coated bullets.

What he put this down to was; the slippery moly coated bullet was moving off down the barrel faster and so the powder was forced to burn in a larger volume, and therefore burned less efficiently, hence lower final velocity.

Now what about rifling?

Having to spin a bullet is a waste of energy. I'm too far away from my text books and too lazy to work out the formulae myself for how much energy is wasted.

I think we are over due a look at how to do without rifling in small arms:

it wastes energy we could use for velocity,

it complicates manufacture,

it attracts wear, erosion and corrosion, and,

it complicates accuracy, with a bullet flying a complicated 3d cork screw trajectory instead of a simple 2d trajectory (See Mann's; "the Bullet's Flight" reprinted by Wolfe).

Anyone out there want to design a streamlined aerodynamically stable projectile that does not require a heavy sabot to be accelerated up the barrel with it?

After all of that: shoot whatever does the job...

A New Helper

The security guy came to site today and between us, we cleaned out all of the remaining services. That's more work than young George did in over a week.

The critters living in those holes were varied. We were expecting and got lots of big cockroaches. We managed to save one big centipede, but another was getting just too dangerous, so it got killed (it was about 12mm diameter and 100mm long) there was also a long skinny black baby snake that we tried to get out, but it ended up looking too dangerous to handle. I haven't a clue what it was, so didn't take the risk. The geko was out and away in a flash.

It's probably just my imagination, but I can still smell the runny human turds that were all around that area. I know that many of the people don't have access to a home toilet, and public facilities are none existent, but I think that smell will always remind me of Loo-anda.

Sorry, it's getting late...

Another brighter note, the second rig that the fat controller has been promising me finally arrived at 6 pm tonight.. Who knows? the project might just finish on time.

More pictures from the Fort

South African Scrap metal.

Two of 3 multi barrel repeaters (the fore runner of the machine gun) together with bits of bigger artillery pieces. I don't know what calibre the things are in, but despite the grime, the bores are packed with grease and they appear to be in useable condition.

Notice the empty "Cuca" (cheap beer) can by the wheel of the big gun.

Unexpected Day Off

Got a phone call from the crew about 7 o´clock this morning saying that they were staying at their compound for the day.

Apparently a rumor has gone around the expats that immigration officials would be raiding construction sites today looking for people without work permits, to fine them.

This is supposed to occur every couple of months, so whether the tip-off was real or imagined, I don't know.

I did see a quote somewhere saying:

"If something seems illogical, a government or money must be involved"

I think both apply in this case, but it wasdn't all bad, I got to do some more reading of the "unbearable lightness"...

Road safety 2 and a quiet day

It's been a quiet day, not a lot to report.

I pissed all the other males around the breakfast table off with a monologue about cultures where the females, do all of the work, earn the money, have a pregnancy every year, do the house work, child rearing, cooking, cleaning, make the clothes etc, while the males make the important decisions ("I'll have another pint if your buying").

On the subject of hard working males, George, my helper appears to have given up on coming to work, his mate, the security guard, who recommended him is very embarassed, and will be coming instead.

The guy who comissioned the ground investigation is back from leave and looking for info, so it looks like a few busy evenings writing up (no, I don't drink, but I can have a photo uploading while I work).

Here's another shot of a roadworthy vehicle (that is, roadworthy by Angolan standards, the shot might be veiwable by imagination only if the net stays as slow as it is now).

Road Safety

The standard of roadworthyness and road safety here is absolutly apalling. It is not everytime that I have the camera ready to catch a really unroadworthy vehicle or load, but have managed to get one or two:

This guy had already dropped part of his load, here he is patching it up in the middle of town.

The Fort

Had a brief cringe moment this morning, there was a body lying in rags on the pavement outside the site. No cops came and it was gone by dinner time, so must have still been alive…

Went around the fort this afternoon. This acts as the national military museum, and houses all sorts of old cannon, together with trophies from the war of independence and conflicts with South Africa and South African backed forces, so there are a pair of shot up Harvards, with guns still fitted, a hoard of shot up armoured vehicles and artillery. The big guns still have breeches intact, showing details of Blish Locks and falling blocks.

Inside the fort, old guns are scattered everywhere, with termites eating the carriages.

Of great interest was an improvised gun with a rubber band for a main spring, the wooden magazine and the tin trigger guard seem to be more for psychological than physical use.

Half an hour in a scrapyard would produce one. And it looked like the cartridge was home loaded using a recycled bullet and case. I don't know what the propellant was, but from the thickness of the barrel and the breeching arrangement, I don't think it was very hot.

I´ll be posting more pictures from the fort over the next few days.

Sewerage

Sewerage flowing around the town is a common site, however with this lake there were tankers sucking up the water to allow a repair to be made. The depth of the pool was quite something.

Slums

Any excuse to post a few shots of the slums. These ones at Miramar, not far from the US embassy, have views over the port. The fence to the right is a sports club clay shooting range. Just imagine the rattle of broken clays, wads and shot falling on your tin roof. The ground by the fence is a mass of human crap, and heavy rains will make the slope the shacks are built on crumble.

The ones at the bottom of the hill, run the risk of something bigger falling on the roof with the crumbling old chimney, but the playing area, complete with waste water and chickens pecking around might yet provide players for the next world cup team, in the same way that the back streets of pit villages provided Britain's footballing stars.

Stopping Power

Having some shooting related thoughts, they’re a bit nerdy so if you don’t shoot, stop here.

I’ve seen a lot of debates recently about “stopping power” and have some serious doubts about what I have read. I only have limited experience on animals and hope never to see a person getting shot, but still, the doubts remain.

I’ve probably inadvertently plagarised a few people’s thoughts here, but have added a few of my own too.

I’ll start with a usual gunzine article “14 inch Naval gun or .22 BB Cap, which is best?”

It makes sense to me that the Naval gun will do more damage on a target and have “better stopping power” than a bb cap,

BUT:

Does a slight increase in bullet diameter have a statistically significant increase in instant incapacitation? and, at what increment of bullet diameter for a given sectional density and velocity does that become statistically significant?

Then, how much of the advantage in incapacitation is off set by a lower hit probability from a heavier, harder kicking gun and a lower number of shots carried by each person?

Even fatal hits with none expanding bullets, lets say through the heart, give a critter about 40 to 60 seconds of running about as though nothing was really wrong.

All that I have seen and read suggests a massive variability in wounding effect from identical hits on identical animals with identical bullets at identical velocities.

As an example, the one and only shot that caused an instant knockdown with a chest shot on cattle in the trials that lead to the recommendation that .45 was the minimum acceptable caliber for a US service pistol, was with

Wait for it!

Here you are: .30 Luger!

I have read Peter Capstick joking that stopping power varied with local tides and the pollen count.

With African big game, kills are usually by a shot into the heart, Brain shots are for those with nerves of steel, as the target area is small and on Elephant, Buffalo and Rhino, it is also well protected. A charging elephant holds its’ head back and presents several feet of bone to penetrate before reaching the brain.

Shots to the Skeleton, for example the shoulders may drop an animal allowing a follow up fatal shot.

Interestingly, Elephant and Buffalo culling was (?is) frequently carried out using the L1A1 (FN FAL) with military 7.62mm 156 grain FMJ.

For Hunting, 6.5mm 160 grain round nose FMJ had the penetration for some use on elephant, and 140 grain 6.5mm is still used for much European elk (moose) shooting. Unfortunately, the pencil like 160 grain bullet lacked structural strength, being prone to bending and going off line on its long journey to the vitals.

From my limited engineering view point, the heavy calibres had the advantage in having a less slender and therefore more rigid structure for a similar sectional density, when compared to the likes of a 6.5mm.

Possible lesser advantages were a lower ratio of surface area per grain of bullet weight, therefore slightly less drag per grain than the small diameter bullet, and proportionately less low density jacket material in their construction.

The much more massive bullet would also be carrying more energy at the end of its long travel through guts, bone and muscle, so was probably better able to break a major bone, say a shoulder or a pelvis.

I have left out the size of wound channel and “shock effect”. “Shock Effect” because even the big “stopping” rounds such as .577 and .600 are still too small compared to the size of the animal to set up a hydrostatic shockwave similar to that experienced by a rodent being hit with a hyper velocity .22. I would argue that the same is true with military rounds and human sized targets which have their adrenaline flowing.

With diameter of wound channel. I remain to be convinced that one or two millimeters change in diameter of either a solid bullet intended for big game, or a tumbling military ball round will make a statistically significant difference.

Infact, the shock wave due to a bullet’s passage will obey the inverse square law, as the distance from the bullet doubles, so the energy of the shockwave will reduce by the square root.

As an analogy, heat two bullets of different calibers to say 200 or 250°C (any higher and any solder will start to melt). Quickly tip them onto a heat resistant surface a reasonable distance apart, and, quickly again, see if you can detect much difference in the radiated heat at a given distance. The skin on the back of your hand is a pretty good heat detector.

Like shockwaves, the radiated heat decays with the distance according to the inverse square. (if you double the distance, the area is squared).

Don’t however confuse the contained heat in the bullets, this is analogous to momentum and is directly proportional to bullet mass (assuming equivalent proportions of jacket and core between the two bullets, as these materials will have different specific heat capacities). Momentum would only be fully transmitted to a target if the bullet failed to exit, and an exit wound is a good path for quick blood loss, leading to loss of consciousness.

The changes in military rifle caliber that I have seen suggested would go from 5.56mm diameter to something like 6.5mm or 6.75mm diameter. To me this sounds like a waste of time money and effort. I don’t think it will give a statistically significant increase in number and speed of incapacitations.

Go on someone, give me hard evidence that I am wrong. I’ll even give you a head start by setting the bar low at 95% significance, one tailed T Test.

Death on Site

Got to site late this morning, my driver had been stopped by the cops for out of date car tax.

I was greeted by the news that the one legged man in the picture, was lying dead between the footpath and the site fence, and a hoard of his relatives had appeared out of the woodwork to mourn.

We had been worried about the guy as we had not seen him for a few days, but he re appeared yesterday. He had been asking one of the crew for money, the guy from the crew said he would buy him food, but he declined the offer and said he wanted whiskey.

This morning he was curled up as though asleep (contradicting the story from some people that the cops had shot him for stealing. Our experience of him was as a pretty harmless and un threatening little guy).

Some of the crew had been speaking to the relatives, Apparently the guy was a refugee from Cape Verde. The crew guessed he was mid to late forties, so quite old by local standards.

My helper got mugged

Young George has got the job of helping me.

He's cleaning storm drains out at the moment, so that I can record the size and depth of the services. It is a horrible job, as some have been used a toilets and contain human turds, dead rats etc.

George's moral is therefore not very high, this is not helped by him not being used to using a shovel, his hoe (mattock) was stolen and he regards manual labour as being below his station in society.

He showed up on site late yesterday, sporting a grazed chin and a cut inside his mouth. My Portuguese is very limited, as is George's English, so I thought he had been mugged on his way to site and sent him home to clean up.

I found out afterwards that it happened the night before, and his mobile phone had been stolen.

Word among the expats is that a big crowd (the figures spoken were 2 or 3 thousand) of street criminals have recently been released, to cure overcrowding, and because they were originally locked up without due process...

Word among the Angolans is that if the Police think a criminal is dangerous, they shoot first. So perhaps there is a permenant cure for overcrowding in the way...

It Rained!

Early morning on the 19th, the sound of dripping water woke me up, I thought it was not supposed to rain until about November time (the previous rain shower was in mid May), So the next thought was, has a dog got into the compound and found my boots to chew?

No, it was rain dripping off the roof. Blame global warming.

In town, some of the taller buildings were shrouded in mist and it was downright humid.

Coming back for lunch and there was a holdup while a tree was removed from the roof of a girl's car. It looked like the roots had given up the struggle and the tree had come over. Possibly during the night, as the girl was looking on, un-hurt.

The soils in Luanda are often loosly packed sands, held together by clay at the grain contacts. When they get wet they behave like a sugar lump does when it gets wet, and loose most of their strength. Most of the streets have water running down their gutters from burst pipes, so perhaps that is what happened to the tree.

Just why do I hunt?

This is a follow on from my vegetarian dilemma. I enjoy hunting, I enjoy stalking the animal, I enjoy watching and learning about its’ behaviour and habits. I also seem to enjoy the outdoors more when I’m concentrating on staying down wind and searching for signs of my beasties.

Almost all of the most effective conservationists that the world has seen have been hunters. They were people who respected and valued their animals and birds, along with their habitats. They were people who possessed the interest and motivation to do something positive (having the time, the funds, the contacts and the persuasive powers were probably equally important, but it was the interest that set the process in train).

But why do I want to kill the beastie? I know from all of the animals that I’ve kept, that each has its’ own personality and ways of interacting with humans and with its’ own kind. Trying to tell myself that this does not apply to all of the birds and mammals is self deception.

I don’t actually need the meat, the skin or the fur, although I have to say that I enjoy game meat (exceptions are hare and grouse, which I find a bit too strong). But does my enjoyment outway a little life? I don’t know.

Hunting does mobilize a great deal of funding that benefits more general habitat maintainance and restoration. It only takes relatively few predators to clean out a population of ground nesting birds, but the keepering also has its’ undesirable side effects. Control of stoats and weasels allows rabbits to breed to plague proportions, there is also constant inward pressure of predators seeking rich pickings in the vacuum of the keepered area.

Emotionally, I was probably more attached to a stoat, than I think any other animal I’ve known. She used to eat half her own weight in rabbit meat each day, so keeping a stoat now would be a moral crisis.

Never the less, hunting provides more effective funding than other voluntary contributions, and the people providing the funding are astute business people who are very effective at ensuring value for their money, unlike the state or the voluntary groups.

Is it a real problem that it favours species over individual, and that it favours some species over others?

I’ve heard many soundbite type arguments on both the pro and anti side, most of which I can criticize quite effectively, however, this is my personal search for reasons, and I really don’t know.

A Day of Rest

The Crew were not working to day, so we took the opportunity to go to Mussulo, a sand spit off the coast to the south of Luanda.

There is a resort run by Jembas, the “Onjango”, I think it means baobab.

The morning was cool and overcast, however the sun came through around mid day and the feeling was a bit like a warm September’s day in Britain.

The speedboat ride across to the resort is a real stress buster, you leave the grime, the traffic and the hassles of Luanda behind, and enjoy the beach and the coconut palms.

We shared the boat with a party of nuns, who all crossed themselves as we set off.

The trip was well worth while, and, I’ve finally got into reading “The unbearable lightness of being”. Patty gave me it shortly after we first met, and I’ve started it several times, but ‘am ashamed to say that I never got very far.

New style of AK

Travelling through the city during the week, I saw one of the police Hi-Lux pickups with a back to back bench seat running lengthways down the truck back, and a full load of cops in body armour.

This is nothing unusual, both the police and security companies carry their response teams in this fashion.

What I hadn’t seen before was the black plastic fore end on the AKs. This was a square-ish u section extending well forward towards the gas port on the barrel. From what I can remember, the steel folding stocks were conventional enough.

The guns appeared to be new, in contrast with the battered AKs and Uzis that I normally see being carried by cops (there were two cops with dry, rusty looking Uzis patrolling the road beside the site yesterday). The view out of a car up a rusty bore on an Uzi is not too inspiring, particularly as I don’t know if the bolt is back (cocked)or forward (safe)on the ill maintained old guns.

Apparently cops here get upset if they see photos being taken, so, no photo, sorry.

More interesting buildings in Luanda

The big building under construction is the new office building for the state oil company.

I have heard rumors of several workers falling from the un-protected edges and of excessive unplanned foundation settlement, but they were not from people within the construction industry so I cannot confirm their authenticity. The yellowish derelict building on the right is the shot up former UNITA offices (UNITA and the MPLA were the main combatants in the civil war, with the MPLA controlling the cities and UNITA, the countryside. The MPLA is the biggest party in the present Government).

Some Interesting Buildings in Luanda

I spotted the tin building the other day and got the chance to photograph it yesterday after dropping a colleague off.

It is situated a couple of blocks inland behind the Banco Nacionale (the fantastic pink building with the dome on the Marginal (sea front).

I have no idea what it was for, the style looks colonial, but not Portuguese. French perhaps?

Apart from some missing pieces, it does not seem to have been trashed too badly, and there were security guards sitting in it, so presumably someone has plans for renovating it.

Getting Measurements from Photographs

Measuring from photographs

A long while back, I remember a letter to the editor of one of the home shop engineering magazines asking whether it was possible to obtain measurements from a photograph.

Coming from a semi geographical sort of education, I was familiar with photogrammetry and can generally see 3d from a pair of stereo photos without using a stereoscope. The easiest way is actually to put the images side by side but with the left hand image on the right, then to look at the images cross-eyed. It might take a bit of shuffling of the image positions and it takes a little practice, but after a while, that imaginary 3d image that you get in the middle can be scrutinized.

I’ll not go into the theory of photogrammetry, there are several links from photogrammetry societies which do that very well. But it is possible to manually, mechanically or digitally obtain accurate 3d measurements from photographs.

This divides into two systems:

Aerial photogrammetry, where distances are large and corrections are necessary for things like the refractive index of the atmosphere.

Close range or architectural photogrammetry, where you are more interested in 3d detail and views that are not necessarily on a regular parallel grid.

Digital cameras speed up the image capture, and in the case of the better digital SLRs provide almost the accuracy of traditional “metric” cameras. Rollei still make film and digital metric cameras, at a price.

Probably the easiest way to get into this is to use Arpenteur, a web based photogrammetry programme.

Photomodeler provides one of the lowest cost options and has excellent free tutorials to download. Its’ disadvantage is that it does not allow you to view your photos directly in 3d, this is not such a problem on engineering structures, but on say a rock slope, does present a problem.

Photomodeler light used to be available as shareware, but is now very difficult to find.

Both Adam and CSIRO (Sirovision) in Australia have mining orientated packages that allow the automatic generation of a 3d point clouds (similar to what you would obtain with a laser scanner), that you can then render with the image from the photos, allowing easier examination and measurement of natural structures. particularly ones that you don't want to go near in person. Their web sites have sample images.

Most of these measurements can be linked to form 3d cad models for use in CAD, CAM and CNC machining.

So, that water pump body you needed for the 1920’s tractor that the guy would not sell you, can be photographed, a 3d model made in the computer and your uncle, Bob, who works in a machine shop can set one of the machines to make a couple of them on the night shift…

A Moral Dilema

I like meat, good meat, from a mature grass or heather fed animal, that has had time to develop some muscle texture, some flavour and good marbling of fat through that muscle.

I like mutton (from a fella that’s been running around for five years with his nuts off), slowroasted, then finished off in a hot oven to crisp the fat (nothing worse than soggy, greasy meat). Forget gravy and sauces (only crap meat needs sauces and spices, good meat is capable of going solo, any accompaniment just detracts from the experience.

I like Beef, from a mature beast (none of your under 30 months shite), from a slow growing breed that gives good fatty marbled meat, well hung before it is jointed (about a month sounds right). Cook it blue, rare, medium or, well done, delicious!

You can send the battery rat chicken and M-dogburger processed shite to the bin. The stuff that comes in from Brazil, Thailand etc only competes on the basis of low standards.

Brazil in particular, has ranches where the land was never paid for, any indigenous people were forcibly displaced, prisoner labour can be used for a couple of dollars a day, and if they refuse to work, they can be shot. Residues of banned hormone growth promoters and drugs still keep being found, animal welfare is Zero and traceability is Zero.

How is that supposed to be fair competition with Europe’s over regulated agriculture?

But that is getting away from the point, which is, I am starting to become more and more vegetarian.

Yes, me, who has shot critters by the thousand!

Anyone who has kept animals knows that each animal has its’ own personality, forget what Descarte claimed, that only humans have “mind” and that animals are just automata.

Probably my biggest turning point was Bunny, a tiny baby wild rabbit that Patty found on the steps at work, she had fallen about 60 feet over a cliff onto concrete and had suffered an open fracture of a back leg.

We fed her on cows milk (actually a bad thing as all rabbits are lactose intolerant, all replacement milks give them the shites) and took her to the vets, where her leg was amputated.

I was off work at the time with glandular fever and nursing Bunny gave me some purpose. We got her two companion guinea pigs which I thought were both female (I got two for the price of one, because they were lousy) one had all of its hair chewed short, apart from a tuft on either side of its’ face, she got called Wart hog, the other was really wild to start with, and turned out to be male, he’s called Wild hog. The two supposedly domestic hogs were so wild, they made Bunny wild for a while.

Anyway, all have distinct personalities. Bunny is very placid. Her missing back leg means that she is not particularly mobile, this is compounded by a damaged front leg (received at the vets where she was supposedly being looked after, name of vet available on request!). She therefore spends a lot of time lying down, and is particularly good at cuddling up, either with us or the hogs.

It isn’t sentimentality, I can quote the references for the cognitive psychology and neurological basis for emotions, and even rattlesnakes are capable of motherly love, yes, emotions occur in the part of the brain that we share with reptiles!

So where does that leave me? Respecter of animals as individual beings and eater of good meat?

ps, I've just squashed two potentially malarial mosquitos, without moral qualm.

Blogs that I visit.

People who know me know that I shoot, my source blog is therefore Alphecca, run By Jeff Sawyer, who describes himself as a “Gay gun nut” The content though is mostly shooting rather than gay orientated, and very well written. (www.alphecca.com).

Jeff’s list of links is superb, they are in alphabetical order and open in new windows, so there is no messing about with back tracking.

From Alphecca, my route is normally to “Irons in the fire” a blacksmithing and shooting blog. Firehand writes very personally, and I find his blog totally addictive.

John Lott is a professional researcher into gun crime, firearms controls and media bias, he presents an authoritative commentary on current issues affecting gun ownership, use, abuse and legislation.

Xavier Thoughts is a blog by a gun carrying nurse. One of Xavier’s specialities is “idiots with guns” which serves to high-light poor gun handling. Xavier is also one of (if not the) keenest minds in gun blogging.

The bitch girls.
This one is a lot of fun, it would piss off anyone with left of center politics, but hell, it’s good...

The photo is totally irrelevant, it shows a little bit of private enterprise in a socialist state. One of the guys in the slum, collects sand from the site in a plastic bucket and is making concrete building blocks out of it. If it gets a few essentials for his family, I'm all for it. If it buys Cuca (a cheap beer), I suppose he's worked for it.

Beggars

The local Beggars are varied in age and number of limbs however, all seem to have mental health and substance abuse problems.

The usual opening line is “my friend” or “chef” (boss) followed by a demand for money. One yesterday appeared to be big, young and physically fit, he could speak a little English as well. He was looking for 50 Kwanza (80 Kwanza = 1 US Dollar, petrol is 40 Kwanza for a litre).

Our drill supervisor took pity on the one legged guy, who usually eats from the trash pile (all in the photo, by the way, most of that waste paper is coutesy of a United Nations office). The next time we saw him, he was drinking beer.

There are a few people with withered limbs from polio. I saw one teenage schoolgirl, in smart uniform, with a withered leg, this lunchtime.

Life on site; 2

The chickens from the slum come onto site, one, which looks like a game banty is particularly tame and visited me in the trial pits. They also appear to be fond of the dust on site, and frequently scrat around the rig.

For food, they do not appear to have grasped the concept that you can not scrat a sheet of paper out of the way wheile your other foot is still standing on it, and today, we had two cocks fighting over polystyrene foam.

They all appear to prefer to eat polystyrene over almost anything else.

Trash from the surrounding buildings is tipped at one corner of the site for collection by the municipal (building site style) dump truck.

Waste food on this heap provides food for the chickens, a skinny, wormy black bitch that has tits almost touching the ground, and some of the local beggers, who I will feature in another post.

Life on site; part 1

In cleaning up the site we have probably, no, I'll correct that, we have certainly removed much of the cover used by local critters.

When we tried to clean the trash out of some concrete manhole rings to see what services were at the bottom, the wildlife included two big lizards, hundreds of big roaches and a small cat, which my helpers eagerly persued with shovels.

I think part of the chasing was revenge for me telling them that I like children, but couldn't eat a whole one...

Critters still keep showing up, and I'll post a few of them as time goes by.

This particular one gave me a big fright. I'd picked up an old flare tube (I knew it was empty, after one of my helpers picked it up before I could stop him, on our first day on site). and a length of reptillian tail slid out.

I quickly spotted that it had legs and carefully tipped it out, so that I didn't cause it to shed its' tail. It soon settled down in my hand, and once the photography was over, I let it go under some rubble.

Just don't mess...

When I phone friends and family, one question keeps on cropping up,

am I safe on site?

To answer that one, I get transported by a local driver, who knows the signs of trouble, and on site I have a crew of drillers containing Zulus, who pride themselves on their warrior credentials, I also have 24 hour security guards.

I took a photo of one of the guards from the bottom of a hole, while he was standing on the edge. It worked so well that some of the other guards asked to have their photos taken, so I held the camera about six inches off the ground. It seems to have worked quite well. The guys come out looking really tough.

The difference between those truncheons and a magician's wand?

The wand is for cunning stunts.

Actually, apart from drunks and glue sniffers who come begging, we don't get any bother. I don't know whether the Angolans have always been a placid people but thirty odd years of civil war is enough to make anyone tired of violence.

Square Threads

I know that anyone who has ever tightened a nut and bolt has probably seen stripped threads…

I know as well that broadly square section threads (I’m including Acme type threads in with this) have their place in drive systems such as lead screws. However square section threads have a major disadvantage where repeated shock loads, load reversals or load and unload cycles occur.

This is due to the sharp angle at the root of the threads.

The other morning, a piece of drilling equipment (the trip monkey for standard penetration testing) fell to pieces. A shaft, presumably of something akin to 0.4% carbon steel had pulled out of a presumably mild steel anvil.

On inspection, the threads from the anvil were still in place in the groove of the threads on the shaft.

Once these were peeled off, it became clear that the fracture had propagated from the sharp angle at the root of the thread and in some places, had actually passed below the root on the opposite side of the thread.

What importance has this?

Well, around the end of the 19th and beginning of the 20th century, intuitive craftsmen knew that cracks started from sharp angles in stressed objects. However it seems that some (perhaps almost all) university trained engineers assumed that the stresses were carried uniformly through the solid, hence we see rifle actions such as the 1903 Springfield and the 1914 and 1917 Enfield with square form threads in the receiver rings.

It was only much later that Griffith undertook his research on stress concentrations and crack propagation.

Highly stressed threads, such as those in rock drills are now of “rope” form, with no sharp angles to form stress concentrations.

The Springfield and Enfield have proved their reliability with many having shot out several barrels in their long lifetimes, this is despite, not because of the square form barrel threads.

That Volcano in Northern Chad

I still have not found out how to put more than one photo up on a post, so here is the volcano that I think is probably in northern Chad.

If anyone knows what the volcanic districts in western Sudan, northern Chad and southern Libya are connected to, please let me know

The Cockroach Theory of Mind

Forget all you have heard of grey matter neurons and hemispheres of ther brain.

In certain characters:
Above eye level the cranial cavity is empty

Up to eye level it is filled with a viscous liquid

Floating on the liquid is a cork (it's about the size of a wine bottle cork)

sitting on the cork is a cockroach

The hair continues growing into the cavity, in black people it is a bit like telephone cords, all springy, in whites and asians it tends to be straight and hang down obstructing the cockroach.


The cockroach is the controller. On command, he paddles his little cork around and connects up the inner ends of the hairs, in much the same manner as old style telephone operators used to do.

So, for example, the boss man says: "Sweep the yard"

The cockroach paddles the cork over until he can reach and connects the hairs for "sweep" and "yard".

The individual then goes and sweeps the yard. At this level the system works very well, however, we are all inclined to try to use systems for more than they were originally meant to do, and this system is now exception:

The boss man is in a hurry and needs several things doing.

"Sweep the yard, feed the dogs, bag some corn and chop some fire wood. Then, when you've done that, fuel the truck.

The cockroach sets off and connects "Sweep" to "Yard", then quickly paddles the cork so it can reach "feed" and "Dogs" and sets off in the direction of "bag" and "corn".

Unfortunately by this time the fluid is starting to slop around and the cork is not the most stable means of transport, so the cockroach falls off and lands on its back, legs in the air, and unable to reach up and make any connections.

I'm sure you've seen the look of total blank and confusion that appears on a face at this stage.

This is rapidly followed by a finger coming up and probing the inner recesses of a nostril or an ear.

These are automatic responses, they are helping the cockroach back onto the cork.


Ps
Next time you see a cockroach, don't hurt it, it might be lost and someone might be looking for it.

The site

Obviously I don't want to say who's the site is, or exactly where it is...

First view of the site, the boundary fence has big holes in it where the tin sheets have been stolen to be used a roofing.

The area had been used as a garbage dump for 30 years or so until organised garbage collections were started again in the city. There was a large heap of garbage in the middle of the site and a loading shovel loading it into a single wagon, which due to the traffic in the city, had a very slow journey to the tip and back.

My initial preconception that at least an African site was less likely than a European or American urban site to have syringes and needles on it was wrong. it looks like someone has tipped hospital waste on the site, including needles.

I came prepared with steel soles in my boots, and I'm careful about not touhing anything that I can't see. Add to that Angola's isolation means that AIDS has not exploded here -YET.

Only about 3% are HIV positive, which is a lot lower than the almost 100% rate for junkies that drop their needles anywhere else in the world.


That is not the best of it though....

There is an area of slum near to the site, and the inhabitants use the site as their toilet, with children and adults alike coming in, dropping heir pants and crapping.

We also had a leaking sewer (how many times have I been told that a site has no services on it, only to find it has) which the children were having a great time playing in.


We have had a few local drunks and beggars coming in. The security guards, and on one occasion a cop, are good at chasing them.

A Woman came in yesterday selling what looked like ginger root, some scruffy old pop bottles filled with muddy brown liquid and what looked like foil wrapped sweets.

I didn't understrand the security guard's explanation, but gather that these were all supposed to be endowed with viagra like properties.

Once I manage to get the photo's up, It should give an impression of the city, the site and the company we had in the trial pits. The garbage smells as bad as it looks and the cockroaches are enormous.

Up to Luanda

South African Airlines would not do an E-ticket for Luanda, so it was up early again to collect my ticket and check in.

It did no harm, I was able to have a good look through the book shops and get a coffee before meeting Dick. Also bumped into a guy I knew from last time I was here.

flights into Luanda are usually crowded, I've heard rumors about restrictions on the number of flights by foreign airlines, but have no proof.

Anyway, got a window seat upstairs, where the cattle class has a little more room. got a bit of a view of the Okavango, and a view of the fantastic linear landscape (fossil dunes?) in south eastern Angola.

The view on the approach to Luanda was every bit as grim as last time, and still with standing water in some streets. this was a surprise as this is now the winter dry season.

The que for immigration was as slow as ever, I'm a little more complacent about the mildew covered air conditioners in that arrivals hall, but the mosquitoes still get swatted when they come close.

Fortunately my baggage had arrived (it was on the floor when I got to it), and a driver had been sent to collect us. I made the mistake of letting a guy who appeared to be with the driver carry a bag, it cost me 2 dollars.


my photo is of an unfinished tower block in Luanda, rented out on the cheap. No services, no rails on the edges, and precious few walls.

A Long Trip

I'm writing this up a week late. Last Sunday became a very long day, I was still tired after a 16 hour day on the Monday, going to Kerry and back, to look at quarry faces, and a 22 hour day Tuesday, going to London and back to get a visa. (at least I did manage to fit in a brief trip to Foyles bookshop, to top up on frighteningly expensive text books).

Add to the tiredness the sudden realization that I could not find my passport. It wasn't in the office or the house.

Forget any possibility of finishing off a report before going, it was panic time.

I eventually managed to contact Patty, (her work wants her to leave her phone switched off and well away from the working area. It's more a matter of obsessive compulsive disorder than anything else, and it makes it very difficult in emergencies like this). Sure enough, the passport was still in the pocket of the coat I'd put in her car when she picked me up on Wednesday night.

Monday morning was a 2:30am set off for Dublin airport and a 6 am flight for Amsterdam, got a window seat, but it was cloudy all the way.

I had an aisle seat in the 747 flight to Jo'burg. I asked if anyone wanted to swap, no one did, and the spotty youth in my row who said he preferred a window seat promptly pulled his blind down and kept it down for the rest of the flight. I was near a door, so used the window in it and became the target for the only middle aged hostess to jab me in the ribs when she came past for some imaginary infringement of her sense of order. All of the others were fine about me being there.

It was worth it, got a good view of the Dolomite Mountains, with the Venetian lagoon in the distance, a little of the Apennine hills and lots of Libya.

What came as a real surprise was flying over a couple of huge volcanic areas in the Sahara.

These had eroded cones and plugs of basalt and intrusions of either a yellow coloured intermediate rock type or else severe alteration in the core of the cones and some dykes.

Further south we passed an recent volcano with a large summit caldera containing 2 vents.

I had no idea that there were volcanoes in that general area so I've checked it out on Google maps (click the satellite box). It looks like the big areas of eroded basalt are in southern Libya and the best contender for the big volcano is in northern Chad. The arid climate, the two vents and the white deposits in the vent all match.

There is another Volcanic region in western Sudan, just east of where the border with Chad goes from straight to sinuous. One of the volcanoes there looks simillar, with two vents in a central caldera, but the climate appears to be much less arid than the volcano I saw.

I don't know what structures these centres are supposed to link up to, the area was very arid and, with very rough terrain, so it is probably little studied. There were also areas of particularly iron stained rock in the general area.

South from the Volcanoes and the river beds began to have bushes on them, gradually these spread out and thickened, and we were flying over granitic landscapes with thick bush eventually becomming thick rainforest with impressive cliffs of sedimentary rocks.

The cloud cover also thickened up and we had some impressive castellanus and Cb development.

The scumbags wanting to push my trolley or carry my bags were surprisingly thin on the ground at the airport, perhaps the cold (14 c) had sent them into hibernation.

The cool and early darkness at Johannesburg were a shock after the longest day in Ireland, and a shower and bed at the hotel were a welcome releif at 9pm Irish time.