Thursday, December 14, 2017
Now if I can only get the darn thing to work.
The verge (or crown wheel) escapement is the earliest known type of mechanical escapement, the mechanism in a mechanical clock that controls its rate by allowing the gear train to advance at regular intervals or 'ticks'. Its origin is unknown. Verge escapements were used from the 14th century until the mid 19th century in clocks and pocketwatches. The name verge comes from the Latin virga, meaning stick or rod.
Its invention is important in the history of technology, because it made possible the development of all-mechanical clocks. This caused a shift from measuring time by continuous processes, such as the flow of liquid in water clocks, to repetitive, oscillatory processes, such as the swing of pendulums, which had the potential to be more accurate. Oscillating timekeepers are used in all modern timepieces.
The verge escapement dates from 13th-century Europe, where its invention led to the development of the first all-mechanical clocks. Starting in the 13th century, large tower clocks were built in European town squares, cathedrals, and monasteries. They kept time by using the verge escapement to drive the foliot, a primitive type of balance wheel, causing it to oscillate back and forth. The foliot was a horizontal bar with weights on the ends, and the rate of the clock could be adjusted by sliding the weights in or out on the bar.
The verge probably evolved from the alarum, which used the same mechanism to ring a bell and had appeared centuries earlier. There has been speculation that Villard de Honnecourt invented the verge escapement in 1237 with an illustration of a strange mechanism to turn an angel statue to follow the sun with its finger, but the consensus is that this was not an escapement.
It is believed that sometime in the late 13th century the verge escapement mechanism was applied to tower clocks, creating the first mechanical clock. In spite of the fact that these clocks were celebrated objects of civic pride which were written about at the time, it may never be known when the new escapement was first used. This is because it has proven difficult to distinguish from the meager written documentation which of these early tower clocks were mechanical, and which were water clocks; the same Latin word, horologe, was used for both. None of the original mechanisms have survived unaltered. Sources differ on which was the first clock 'known' to be mechanical, depending on which manuscript evidence they regard as conclusive. One candidate is the Dunstable Priory clock in Bedfordshire, England built in 1283, because accounts say it was installed above the rood screen, where it would be difficult to replenish the water needed for a water clock. Another is the clock built at the Palace of the Visconti, Milan, Italy, in 1335. However, there is agreement that mechanical clocks existed by the late 13th century.
The earliest description of an escapement, in Richard of Wallingford's 1327 manuscript Tractatus Horologii Astronomici on the clock he built at the Abbey of St. Albans, was not a verge, but a variation called a 'strob' escapement. It consisted of a pair of escape wheels on the same axle, with alternating radial teeth. The verge rod was suspended between them, with a short crosspiece that rotated first in one direction and then the other as the staggered teeth pushed past. Although no other example is known, it is possible that this design preceded the verge in clocks.
For the first two hundred years or so of the clock's existence, the verge was the only escapement used in mechanical clocks. In the sixteenth century alternative escapements started to appear, but the verge remained the most used escapement for 350 years until mid-17th century advances in mechanics, which also resulted in the invention of the pendulum. Since clocks were valuable, after the invention of the pendulum many verge clocks were rebuilt to use this more accurate timekeeping technology, so very few of the early verge and foliot clocks have survived unaltered to the present day.
How accurate the first verge and foliot clocks were is debatable, with estimates of one to two hours error per day being mentioned, although modern experiments with clocks of this construction show accuracies of minutes per day were achievable. Early verge clocks were probably no more accurate than the previous water clocks, but they did not freeze in winter and were a more promising technology for innovation. By the mid-17th century, when the pendulum replaced the foliot, the best verge and foliot clocks had achieved an accuracy of 15 minutes per day.
Most of the gross inaccuracy of the early verge and foliot clocks was not due to the escapement itself, but to the foliot oscillator. The first use of pendulums in clocks around 1656 suddenly increased the accuracy of the verge clock from hours a day to minutes a day. Most clocks were rebuilt with their foliots replaced by pendulums, to the extent that it is difficult to find original verge and foliot clocks intact today. A similar increase in accuracy in verge watches followed the introduction of the balance spring in 1658.
The verge escapement consists of a wheel shaped like a crown, with sawtooth-shaped teeth protruding axially toward the front, and with its axis oriented horizontally. In front of it is a vertical rod, the verge, with two metal plates, the pallets, that engage the teeth at opposite sides of the crown wheel. The pallets are not parallel, but are oriented with an angle in between them so only one catches the teeth at a time. The balance wheel (or the pendulum) is mounted at the end of the verge rod. As the clock's gears turn the crown wheel, one of its teeth pushes on a pallet, rotating the verge in one direction, and rotating the second pallet into the path of the teeth on the opposite side of the wheel, until the tooth pushes past the first pallet. Then a tooth on the wheel's opposite side contacts the second pallet, rotating the verge back the other direction, and the cycle repeats. The result is to change the rotary motion of the wheel to an oscillating motion of the verge. Each swing of the foliot or pendulum thus allows one tooth of the escape wheel to pass, advancing the wheel train of the clock by a fixed amount, moving the hands forward at a constant rate.
The crown wheel must have an odd number of teeth for the escapement to function. With an even number, two opposing teeth will contact the pallets at the same time, jamming the escapement. The usual angle between the pallets was 90° to 105°, resulting in a foliot or pendulum swing of around 80° to 100°. In order to reduce the pendulum's swing to make it more isochronous, the French used larger pallet angles, upwards of 115°. This reduced the pendulum swing to around 50° and reduced recoil (below), but required the verge to be located so near the crown wheel that the teeth fell on the pallets very near the axis, reducing initial leverage and increasing friction, thus requiring lighter pendulums.
As might be expected from its early invention, the verge is the most inaccurate of the widely used escapements. It suffers from these problems:
- Verge watches and clocks are sensitive to changes in the drive force; they slow down as the mainspring unwinds. This is called lack of isochronism. It was much worse in verge and foliot clocks due to the lack of a balance spring, but is a problem in all verge movements. In fact, the standard method of adjusting the rate of early verge watches was to alter the force of the mainspring. The cause of this problem is that the crown wheel teeth are always pushing on the pallets, driving the pendulum (or balance wheel) throughout its cycle; it is never allowed to swing freely. All verge watches and spring driven clocks required fusees to equalize the force of the mainspring to achieve even minimal accuracy.
- The escapement has "recoil", meaning that the momentum of the foliot or pendulum pushes the crown wheel backward momentarily, causing the clock's wheel train to move backward, during part of its cycle. This increases friction and wear, resulting in inaccuracy. One way to tell whether an antique watch has a verge escapement is to observe the second hand closely; if it moves backward a little during each cycle, the watch is a verge. This is not necessarily the case in clocks, as there are some other pendulum escapements which exhibit recoil.
- In pendulum clocks, the wide pendulum swing angles of 80°-100° required by the verge cause an additional lack of isochronism due to circular error.
- The wide pendulum swings also cause a lot of air friction, reducing the accuracy of the pendulum, and requiring a lot of power to keep it going, increasing wear. So verge pendulum clocks had lighter bobs, which reduced accuracy.
- Verge timepieces tend to accelerate as the crown wheel and the pallets wear down. This is particularly evident in verge watches from the mid-18th century onwards. It is not in the least unusual for these watches, when run today, to gain many hours per day, or to simply spin as if there were no balance present. The reason for this is that as new escapements were invented, it became the fashion to have a thin watch. To achieve this in a verge watch requires the crown wheel to be made very small, magnifying the effects of wear.
Verge escapements were used in virtually all clocks and watches for 400 years. Then the increase in accuracy due to the introduction of the pendulum and balance spring in the mid 17th century focused attention on error caused by the escapement. By the 1820s, the verge was superseded by better escapements, though many examples of mid 19th century verge watches exist, as they were much cheaper by this time.
In pocketwatches, besides its inaccuracy, the vertical orientation of the crown wheel and the need for a bulky fusee made the verge movement unfashionably thick. French watchmakers adopted the thinner cylinder escapement, invented in 1695. In England, high end watches went to the duplex escapement, developed in 1782, but inexpensive verge fusee watches continued to be produced until the mid 19th century, when the lever escapement took over. These later verge watches were colloquially called 'turnips' because of their bulky build.
The verge was only used briefly in pendulum clocks before it was replaced by the anchor escapement, invented around 1660 and widely used beginning in 1680. The problem with the verge was that it required the pendulum to swing in a wide arc of 80° to 100°. Christiaan Huygens in 1674 showed that a pendulum swinging in a wide arc is an inaccurate timekeeper, because its period of swing is sensitive to small changes in the drive force provided by the clock mechanism.
Although the verge is not known for accuracy, it is capable of it. The first successful marine chronometers, H4 and H5, made by John Harrison in 1759 and 1770, used verge escapements with diamond pallets., In trials they were accurate to within a fifth of a second per day.
Today the verge is seen only in antique or antique-replica timepieces. Many original bracket clocks have their Victorian-era anchor escapement conversions undone and the original style of verge escapement restored. Clockmakers call this a verge reconversion.
Tuesday, December 12, 2017
Next we have Gord's Revell 1/25 scale 1970 Torino Cobra 429 Super Cobra Jet.
Next here is Gord's Conversion using a Motor City Resin body over an AMT 1969 Cobra Fastback model kit. Very nice indeed. The paint is Metallic Indian Fire Red by Model Car World. It's a lacquer that is pre-mixed and ready for the air brush.
Friday, December 8, 2017
Thursday, December 7, 2017
The Etrich Taube, also known by the names of the various later manufacturers who build versions of the type, such as the Rumpler Taube, was a pre-World War I monoplane aircraft. It was the first military aeroplane to be mass-produced in Germany.
The Taube was very popular prior to the First World War, and it was also used by the air forces of Italy and Austria-Hungary. Even the Royal Flying Corps operated at least one Taube in 1912. On November 1, 1911, Giulio Gavotti, an Italian aviator, dropped the world's first aerial bomb from his Taube monoplane over the Ain Zara oasis in Libya. Once the war began, it quickly proved inferior as a serious warplane and as a result was soon replaced by newer and more effective designs.
The Taube was designed in 1909 by Igo Etrich of Austria-Hungary, and first flew in 1910. It was licensed for serial production by Lohner-Werke in Austria and by Edmund Rumpler in Germany, now called the Etrich-Rumpler-Taube. Rumpler soon changed the name to Rumpler-Taube, and stopped paying royalties to Etrich, who subsequently abandoned his patent.
Despite its name, the Taube's unique wing form was not modeled after a dove, but was copied from the seeds of Alsomitra macrocarpa, which can fly long distances from their parent tree. Similar wing shapes were also used by Karl Jatho and Frederick Handley Page. Etrich had tried to build a flying wing aircraft based on the Zanonia wing shape, but the more conventional Taube type, with tail surfaces, was much more successful.
Etrich adopted the format of crosswind-capable main landing gear that Louis Blériot had used on his Blériot XI cross-channel monoplane for better ground handling. The wing has three spars and was braced by a cable-braced steel tube truss (called a "bridge", or Brücke in German) under each wing: at the outer end the uprights of this structure were lengthened to rise above the upper wing surfaces, to form kingposts to carry bracing and warping wires for the enlarged wingtips. A small landing wheel was sometimes mounted on the lower end of this kingpost, to protect it for landings and to help guard against ground loops.
Later Taube-type aircraft from other manufacturers would eventually replace the Blériot-style crosswind main gear with a simpler V-strut main gear format, and also omitted the underwing "bridge" structure for somewhat better aerodynamic efficiency.
Like many contemporary aircraft, especially monoplanes, the Taube used wing warping rather than ailerons for lateral (roll) control, and also warped the rear half of the stabilizer for use as an elevator control surface's function. Only the vertical, twinned triangular rudder surfaces were usually hinged.
The design provided for very stable flight, which made it extremely suitable for observation. In addition, the translucent wings made it difficult for ground observers to detect a Taube at an altitude above 400 meters. The first hostile engagement was by an Italian Taube in 1911 in Libya, its pilot using pistols and dropping 2 kg (4.4 lb) grenades. The Taube was also used for bombing in the Balkans in 1912–13, and in late 1914 when German 3 kg (6.6 lb) bomblets and propaganda leaflets were dropped over Paris. Taube spotter planes detected the advancing Imperial Russian Army in East Prussia during the World War I Battle of Tannenberg.
In civilian use, the Taube was used by pilots to win the Munich-Berlin Kathreiner prize. On 8 December 1911, Gino Linnekogel and Suvelick Johannisthal achieved a two-man endurance record for flying a Taube 4 hours and 35 minutes over Germany.
While initially there were two Taube aircraft assigned to Imperial German units stationed at Qingdao, China only one was available at the start of the war due to an accident. The Rumpler Taube piloted by Lieutenant Gunther Plüschow had to face the attacking Japanese, who had with them a total of eight aircraft. On October 2, 1914, Plüschow's Taube attacked the Japanese warshipswith two small bombs, but failed to score any hits. On November 7, 1914, shortly before the fall of Qingdao, Plüschow was ordered to fly top secret documents to Shanghai, but was forced to make an emergency landing at Lianyungang in Jiangsu, where he was interned by a local Chinese force. Plüschow was rescued by local Chinese civilians under the direction of an American missionary, and successfully reached his destination at Shanghai with his top secret documents, after giving the engine to one of the Chinese civilians who rescued him.
Poor rudder and lateral control made the Taube difficult and slow to turn. The aeroplane proved to be a very easy target for the faster and more mobile Allied fighters of World War I, and just six months into the war, the Taube had been removed from front line service to be used to train new pilots. Many future German aces would learn to fly in a Rumpler Taube.Due to the lack of license fees, no less than 14 companies built a large number of variations of the initial design, making it difficult for historians to determine the exact manufacturer based on historical photographs.
The Technisches Museum Wien is thought to have the only known remaining Etrich-built example of the Taube in existence, an early enough example to have a four-cylinder engine powering it, and is potentially a twin to Gavotti's Taube aircraft from 1911, also said to have been powered with a four-cylinder inline engine. Other examples of original Taubes exist, such as one in Norway, which was the last original Taube to fly under its own power in 1922, over a Norwegian fjord.
The Owl's Head Transportation Museum in Owls Head, Maine USA, is so far the only known museum to attempt the construction of a flyable reproduction of the Etrich Taube in North America. Their example first flew in 1990, and it still flies today with the power of a 200 hp Ranger L-440 inline-6 "uprighted" air-cooled engine.
Tuesday, December 5, 2017
Next A couple of bums are standing next to an old wreck in 1/25 scale. I like the graffiti on the car.
Next is the Saucer from the "Invaders" TV series. The kit was released by Aurora, Monogram, Polar lights and now by someone else. There is lots of aftermarket for this kit. Both models were finished in Alclad.
Saturday, December 2, 2017
During the American Civil War, the Union Navy suffered heavy losses from the explosion of Confederate torpedoes. This experience prompted the Union Navy to design and build vessels capable of using this new weapon. One effort along this line resulted in a screw steam torpedo boat originally called Stromboli, but later called Spuyten Duyvil, after the Spuyten Duyvil area in New York City.
Stromboli was designed by the Chief Engineer of the United States Navy, Captain William W. Wood, who supervised her construction at New Haven, CT, by Samuel M. Pook. The contract for her construction was dated 1 June 1864. Confirmed records of her launching and commissioning have not been found – though period records indicate that she was completed in only three months. On 19 November 1864, the boat was renamed Spuyten Duyvil. On 25 November 1864, she successfully fired two torpedoes. Late in November 1864, Commodore Charles Stewart Boggs was placed in charge of Spuyten Duyvil, Picket Boat No. 6, and steam tug John T. Jenkins which had been chartered to tow the former vessels to Hampton Roads, VA. Upon arriving at Baltimore, MD on 2 December, Boggs turned the vessels over to Commodore T. A. Dornin who placed them under First Assistant Engineer John L. Lay for the remainder of the trip to Hampton Roads. The vessels arrived at Norfolk, VA on 5 December.
The torpedo boat was ordered up the James River a week later to help assure Union control of that vital waterway during General Ulysses S. Grant's drive on Richmond, VA. She arrived at Akin's Landing on 15 December, and she operated on the upper James slightly below the Confederate obstructions through most of the remaining months of the campaign. A highlight of her service came on the night of 23/24 January 1865 when the Confederacy's James River Squadron launched its downstream assault on the Union squadron. During the ensuing Battle of Trent's Reach, Spuyten Duyvil supported Onondaga, the only monitor then on the river.
After General Robert E. Lee evacuated Richmond, Spuyten Duyvil used her torpedoes to help clear the obstructions from the river. Her work made it possible for President Abraham Lincoln to steam up in Malvern and, after Rear Admiral David Dixon Porter's flagship ran aground, to be rowed in a launch safely to the former Confederate capital.
Following the end of the war, Spuyten Duyvil continued to clear obstructions from the James. She then returned to the New York Navy Yard where she was placed in ordinary in 1866. In the years that followed, she was used for developmental work and was modified with many experimental improvements. The ship disappeared from the Navy list in 1880.
In this case, as in the common use of the term in the 19th century, torpedo refers to a device sometimes rigged as a spar torpedo that would now be considered to be a type of naval mine, not being the self-propelled device (called a locomotive torpedo) common in the 20th century.