INTERNAL GRINDING WHEEL. GRINDING WHEEL
INTERNAL GRINDING WHEEL. BLACK TRAILER WHEELS. POCKET COLOR WHEEL
Internal Grinding Wheel
- Used in reference to the cycle of a specified condition or set of events
A circular object that revolves on an axle and forms part of a machine
A circular object that revolves on an axle and is fixed below a vehicle or other object to enable it to move easily over the ground
change directions as if revolving on a pivot; "They wheeled their horses around and left"
a simple machine consisting of a circular frame with spokes (or a solid disc) that can rotate on a shaft or axle (as in vehicles or other machines)
steering wheel: a handwheel that is used for steering
2 pounder anti tank gun
The Ordnance QF 2-pounder (or simply "2 pounder gun") was a 40 mm British anti-tank and vehicle-mounted gun, employed in the Second World War. It was actively used in the Battle of France, and during the North Africa campaign. As tanks became sufficiently armoured to stand up to its shots, it was gradually replaced by the 6-pounder, starting in 1942, though some remained in service until the end of the war. In its vehicle-mounted variant, the 2-pounder was also a common main gun on British tanks early in World War II, and was a typical main armament of armoured cars such as the Daimler throughout the war.
The gun was initially developed as a tank weapon, and made its debut as the main armament of the Vickers-designed Cruiser Tank Mk I. For reasons of economy and standardization, the Director of Artillery accepted it as a basis for an anti-tank gun in October 1934. Contracts to design a carriage were given to Vickers and the Woolwich Arsenal.
Vickers was the first to submit a design, which was accepted as the Ordnance QF 2-pounder Mark IX on Carriage Mark I. A limited number of pieces were built in 1936. The carriage had an innovative three-legged construction. In the traveling position, one of the legs was used as a towing trail, and the other two were folded. When the gun was positioned for combat, the legs were emplaced on the ground and the wheels were lifted up. Woolwich Arsenal's carriage was found to be cheaper and easier to produce than the Vickers design, and with the gun was adopted as Ordnance QF 2-pounder Mark IX on Carriage Mark II. It was conceptually similar, although when the gun was emplaced for combat the wheels had to be removed. This carriage was also manufactured by Vickers.
The unusual construction gave the gun good stability and a traverse of 360 degrees, allowing it to quickly engage moving vehicles from any approach. With the Vickers carriage, the gun could also be fired from its wheels, at the expense of limited traverse. The 40 mm 2-pounder could outperform a typical 37 mm piece such as the German 3.7 cm PaK 36 or the Bofors 37 mm, and hugely outclassed smaller 25 mm and 20 mm weapons used by some forces. On the negative side, the 2-pounder was nearly twice as heavy as PaK 36, and had a higher profile.
One interesting late-war project was the David High Velocity, a Canadian development that allowed 2-pdr ammunition to be fired from the larger-calibre 6-pdr. This was intended was to improve the muzzle velocity of the shot. The system was still being developed when the war ended, the program ending along with it.
One of the most serious short comings of the 2-pdr was the lack of a high explosive shell. Especially if the 2-pdr was the main gun of a tank, which was a very important item when a tank was being used in the infantry support role having only its machine gun to rely on. A high explosive shell was designed for the 2-pdr but in one of the strangest twist of history that was never explained the high explosive shell was never placed in production.
An example of an Irish Army QF 2pndr resides in the museum in Collins Barracks in Cork City.
In the early western campaigns the 2-pdr was employed by two types of Royal Artillery formations: anti-tank regiments of infantry divisions (four batteries with 12 pieces each), and light anti-aircraft/anti-tank regiments of armoured divisions (two 12-gun AT batteries). From October 1940, separate 48-gun anti-tank regiments were introduced in armoured divisions too. Infantry brigade structure initially included an anti-tank company, though it was typically equipped with 25 mm Hotchkiss anti-tank guns; these companies were disbanded later in the war. From 1942, infantry battalions received their own six-gun anti-tank platoons. The organization was different in the Far East theatres. The exact internal structure of AT units was also subject to changes and variations.
The gun first saw combat during the German invasion of the Low Countries, with the Belgian Army, and then with the British Army during the subsequent rear-guard actions at Dunkirk. Most of the British Army's 2-pdrs were left behind in France during the retreat, stripping most of the army's infantry anti-tank capability. Those guns captured at Dunkirk entered German service under the designation 4.0 cm Pak 192 (e) or 4.0 cm Pak 154 (b), the "e" and "b" referring to England and Belgium respectively.
Although the Woolwich Arsenal had already designed a successor to the 2-pdr, the 6 pounder gun, it was decided in the face of a likely German invasion to re-equip the army with the 2-pdr, avoiding the period of adaptation to production, and also of re-training and acclimatization with the new weapon. This had the effect of delaying production of the 6 pounder until November 1941, and it was only in spring 1942 when the new gun reached frontline units. As such, for most of the North African campaign, the army still had to rely on the 2-pdr, aided by the 25 pound
Capital Airlines de Havilland DH 4A Comet
CAPITAL AIRLINES PURCHASE COMETS' was the headline in the Enterprise magazine - the internal magazine of the de Havilland Company. It referred to a (then) recent joint announcement by Capital and de Havilland which disclosed an order for 14 Comet aircraft.
Thus it appeared that de Havilland had done what every other non-American manufacturer needed to do, broken into the United States airliner market in the face of home competition. The argument went: with a foot hold in the U.S. market many more 'knock on' sales could be hoped for. So the announcement was of very great significance.
The agreement specified that the Comets would be powered by Rolls-Royce engines, and including spares, the cost was put at some ?19 million/USD 7 million (year 2000 = ?263/43). Deliveries were to commence in late 1958 with four Comet Mk.4s and late in 1959 with ten of the special variant the Mk.4A.
J.H. Slim Carmichael, who was President of Capital Airlines, said of the deal, The decision to purchase the Comet has been made after a most comprehensive and detailed study of all flight equipment either in production or projected, both in the United States and England. The economical and operating characteristics of the Comet 4A are ideally suited to the Capital system. The Comets will go into service on our major and most competitive routes.
Apparently the same basis for determining economic criteria were used when Capital purchased Viscounts. (ed note - The only financing Capital had available was through the Bank Of England and only for British built aircraft). Projections made before the Viscount purchase had proved accurate when it was introduced on Capital routes in 1955. The Comet order was placed because Capital now wanted a range of pure-jets to operate some 200 mph faster than anything else they then had in use. Capital was one of the biggest domestic carriers in the USA as was illustrated by figures for 1955 which showed that Capital carried 2? million passengers over some 31 million miles!
Capital's Mk.4As were to be furnished to accommodate 74 passengers in the utmost luxury by having 68 persons seated four abreast in two large cabins and six in a forward lounge. The expectation was that passengers would be carried in unprecedented smoothness and quietude, even surpassing the qualities of the earlier Comet models while the speed and economy also show a marked advance. The 4A was to be assembled at Chester as well as Hatfield, England.
The Mk.4A was launched in June 1956 as a short range version of the Comet. The fuselage was stretched and the wing span was reduced. Maximum takeoff weight was reduced to 152.5Klb. The Mk.4A died, when the launch customer Capital Airlines cancelled the order. As a result no Mk 4A was ever built.
Unfortunately Capital suffered sudden financial difficulties, a period of uncertainty and numerous fatal incidents, it was forced to give up some of its routes to rival carriers and was absorbed into United Airlines. The foothold into the US market was lost and the Mk.4A was never produced.
The de Havilland DH 106 Comet was the world's first commercial jet airliner to reach production. Developed and manufactured by de Havilland at the Hatfield, Hertfordshire, United Kingdom headquarters, it first flew in 1949 and was a landmark in aeronautical design. It featured an extremely aerodynamically clean design with its four de Havilland Ghost turbojet engines buried into the wings, a low-noise pressurised cabin, and large windows; for the era, it was an exceptionally comfortable design for passengers and showed signs of being a major success in the first year upon launching.
However, a few years after introduction into commercial service, Comet airframes began suffering from catastrophic metal fatigue, which in combination with cabin pressurisation cycles, caused two well-publicised accidents where the aircraft tore apart in mid-flight. The Comet had to be withdrawn and extensively tested to discover the cause; the first incident had been incorrectly identified as having been caused by an onboard fire. Several contributory factors, such as window installation methodology, were also identified as exacerbating the problem. The Comet was extensively redesigned to eliminate this design flaw. Rival manufacturers meanwhile developed their own aircraft and heeded the lessons learned from the Comet.
Although sales never fully recovered, the redesigned Comet 4 series subsequently enjoyed a long and productive career of over 30 years. The Comet was adapted for a variety of military roles, such as surveillance, VIP, medical and passenger transport; the most extensive modification resulted in a specialised maritime patrol aircraft variant, the Hawker Siddeley Nimrod. Nimrods remained in service with the Royal Air Force (RAF) until they were retired in June 2011, over 60 years after the Comet's first flight.
Development
Design studies for the DH 106 Comet 1944–1947
During the Second World War, the Brabazon Committ
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