Archive for July, 2011

Michelin Tires

Posted: July 31, 2011 in Advertising, History, Vehicles

Michelin is a tyre manufacturer based in Clermont-Ferrand in the Auvergne région of France. It is one of the two largest tyre manufacturers in the world along with Bridgestone. In addition to the Michelin brand, it also owns the BFGoodrich, Taurus, Riken, Kormoran and Uniroyal (in North America) tyre brands. It is also notable for its Red and Green travel guides, its roadmaps, the Michelin stars that the Red Guide awards to restaurants for their cooking, and for its company mascot Bibendum, colloquially known as the Michelin Man.

Roger is a word used in one prominent radio alphabet to stand for the letter R. These alphabets use words to represent letters; such alphabets are known as “radio alphabets” or “phonetic alphabets,” among other names, and are used for many different languages. The alphabet in which Roger stands for R begins “Able Baker Charlie Dog…,” and was the official radio alphabet of the U.S. Navy before 1954. Another familiar alphabet, the NATO phonetic alphabet, which is used by the International Civil Aviation Organization and the Federal Aviation Administration, begins “Alpha Bravo Charlie Delta”; this alphabet uses Romeo for R. There is a page devoted to these alphabets here.

The R that Roger is substituting for stands for received, indicating that a radio message has been received and understood. The use of radio-alphabet terms to stand for other words is common in the military; roger is a well-known example, and another example is Charlie referring to Viet Cong troops, which comes from Victor Charlie, a radio-alphabet spelling of VC for Viet Cong.

Wilco is not from a radio alphabet; it’s a military abbreviation for will comply, indicating that a message that has been received will be complied with. It’s necessary to acknowledge receipt of a message with Roger before indicating compliance with wilco, hence the frequent combination Roger, wilco.

Both Roger in this sense and wilco appear for the first time during World War II


Posted: July 31, 2011 in Aircraft, AVIATION, Science

Contrails (kɒntreɪlz/; short for “condensation trails”) or vapour trails are artificial clouds that are the visible trails of condensed water vapour made by the exhaust of aircraft engines. As the hot exhaust gases cool in the surrounding air they may precipitate a cloud of microscopic water droplets. If the air is cold enough, this trail will comprise tiny ice crystals.

The wingtip vortices which trail from the wingtips and wing flaps of aircraft are sometimes partly visible due to condensation in the cores of the vortices. Each vortex is a mass of spinning air and the air pressure at the centre of the vortex is very low. These wingtip vortices are not the same as contrails.

Depending on atmospheric conditions, contrails may be visible for only a few seconds or minutes, or may persist for many hours which may affect climate.

Condensation from engine exhaust
The main products of hydrocarbon fuel combustion are carbon dioxide and water vapor. At high altitudes this water vapour emerges into a cold environment, and the local increase in water vapor can push the water content of the air past saturation point. The vapour then condenses into tiny water droplets and/or deposits into ice. These millions of tiny water droplets and/or ice crystals form the vapour trail or contrails. The vapor’s need to condense accounts for the contrail forming some way behind the aircraft’s engines. At high altitudes, supercooled water vapor requires a trigger to encourage deposition or condensation. The exhaust particles in the aircraft’s exhaust act as this trigger, causing the trapped vapor to rapidly turn to ice crystals. Exhaust vapour trails or contrails usually occur above 8000 metres (26,000 feet), and only if the temperature there is below −40 °C (−40 °F).

Condensation from decreases in pressure
As a wing generates lift, it causes a vortex to form at each wingtip, and sometimes also at the tip of each wing flap. These wingtip vortices persist in the atmosphere long after the aircraft has passed. The reduction in pressure and temperature across each vortex can cause water to condense and make the cores of the wingtip vortices visible. This effect is more common on humid days. Wingtip vortices can sometimes be seen behind the wing flaps of airliners during takeoff and landing, and during landing of the Space shuttle.

The visible cores of wingtip vortices contrast with the other major type of contrails which are caused by the combustion of fuel. Contrails produced from jet engine exhaust are seen at high altitude, directly behind each engine. By contrast, the visible cores of wingtip vortices are usually seen only at low altitude where the aircraft is travelling slowly after takeoff or before landing, and where the ambient humidity is higher. They trail behind the wingtips and wing flaps rather than behind the engines.

During high-thrust settings the fan blades at the intake of a turbo-fan engine reach transonic speeds, causing a sudden drop in air pressure. This creates the condensation fog (inside the intake) which is often observed by air travelers during takeoff. For more information see the Prandtl-Glauert singularity effect.

Vapour trails or contrails and climate
Vapour trails or contrails, by affecting the Earth’s radiation balance, act as a radiative forcing. Studies have found that vapour trails or contrails trap outgoing longwave radiation emitted by the Earth and atmosphere (positive radiative forcing) at a greater rate than they reflect incoming solar radiation (negative radiative forcing). Therefore, the overall net effect of contrails is positive, i.e. a warming. However, the effect varies daily and annually, and overall the magnitude of the forcing is not well known: globally (for 1992 air traffic conditions), values range from 3.5 mW/m2 to 17 mW/m2. Other studies have determined that night flights are mostly responsible for the warming effect: while accounting for only 25% of daily air traffic, they contribute 60 to 80% of contrail radiative forcing. Similarly, winter flights account for only 22% of annual air traffic, but contribute half of the annual mean radiative forcing.

September 11, 2001 climate impact study
The grounding of planes for three days in the United States after September 11, 2001 provided a rare opportunity for scientists to study the effects of contrails on climate forcing. Measurements showed that without contrails, the local diurnal temperature range (difference of day and night temperatures) was about 1 degree Celsius higher than immediately before; however, it has also been suggested that this was due to unusually clear weather during the period.

Condensation trails have been suspected of causing “regional-scale surface temperature” changes for some time. Researcher David J. Travis, an atmospheric scientist at the University of Wisconsin-Whitewater, has published and spoken on the measurable impacts of contrails on climate change in the science journal Nature and at the American Meteorological Society 10th Annual conference in Portland, Oregon. The effect of the change in aircraft contrail formation on the 3 days after the 11th was observed in surface temperature change, measured across over 4,000 reporting stations in the continental United States.[9] Travis’ research documented an “anomalous increase in the average diurnal temperature change”. The diurnal temperature range (DTR) is the difference in the day’s highs and lows at any weather reporting station. Travis observed a 1.8 degree Celsius departure from the two adjacent three-day periods to the 11th-14th. This increase was the largest recorded in 30 years, more than “2 standard deviations away from the mean DTR”.

Head-on contrails
A contrail from an aeroplane flying towards the observer can appear to be generated by an object moving vertically. On 8 November 2010 in California, U.S., a contrail of this type gained wide media attention as a “mystery missile” that could not be explained by US military and aviation authorities, and its explanation as a contrail took more than 24 hours to become accepted by US media and military institutions.

A ‘distrail’ is short for dissipation trail. Where an aircraft passes through a cloud, it can clear a path through it; this is known as a distrail. Because the plane’s contrail is not yet visible (contrails usually form above 26,000 feet, depending on the temperature and other factors) the distrail looks like a tunnel through the cloud if the cloud is very thin.

Distrails are created by the elevated temperature of the exhaust gases absorbing the moisture from the cloud. Clouds exist where the relative humidity is 100% but by increasing the temperature the air can hold more moisture and the relative humidity drops below 100%, even for the same absolute moisture density, causing the visible water droplets in the cloud to be converted back into water vapour.


Posted: July 31, 2011 in Motorbike

The BMW S1000RR is a sport bike initially manufactured by BMW Motorrad to compete in the 2009 Superbike World Championship,[3] that is now in commercial production. It was introduced in Munich in April 2008,[4] and is powered by a 999 cc (61.0 cu in) inline-4 engine redlined at 14,200 rpm.

BMW manufactured 1,000 production models in 2009 to satisfy World Superbike homologation requirements, but expanded production for commercial sale of the bike in 2010. It features an anti-lock braking system, standard, with an optional electronic traction control, and has an overall wet weight of 207.7 kg (458 lb), and produces 133.6 kW (179.2 hp) @ 13250 rpm at the rear wheel.

The factory race bike used in the Superbike World Championship differs in a number of ways from the production bike. Its engine has a higher compression ratio of 14.0:1 compared with 13.0:1, and it delivers over 200 hp (150 kW) at 14,000 rpm, compared with 193 hp (144 kW) at 13,000 rpm. The race bike has a 44 mm Öhlins inverted fork, compared with a 46 mm upside-down fork. It has 16.5-inch front wheel and 16-inch rear wheel instead of 17-inch and an MRA Racing ‘Double-Bubble’ Windshield. Most significantly it has an unladen wet weight of 162 kg (360 lb)compared with 204 kg (450 lb) for the production model.

On 26 June 2008, Spanish rider Rubén Xaus signed to ride the bike for the factory BMW Motorrad team. On 25 September 2008, Australian former double Superbike World Champion Troy Corser signed to complete the team’s two-rider lineup for 2009. In the 2009 Superbike World Championship season, the highest race result achieved by Corser was fifth place in the Czech Republic, and Xaus achieved seventh place in Italy.

In the 2010 Superbike World Championship season, Reitwagen Motorsport are also racing the S1000RR with riders Andrew Pitt, Roland Resch, and Makoto Tamada. As of September 2010 the highest race result was third place for Corser in race two at Monza, and third place in race one at Misano where Troy Corser took BMW’s first Superpole with a record lap time of 1 minute 35.001 seconds.

Economy Class: Why The Name “Coach?” It all dates back to the 15th century in the town of Kocs (pronounced rather like “coach”), Hungary. That’s where a large four-wheeled carriage called a “coach wagon” was first popularized. By the 17th century, stagecoaches were used to deliver mail as well as for transportation. These operations were mechanized during the Industrial Revolution, but the old-fashioned “coach” name stuck. In the mid-1800s, only first-class railroad cars were called “coaches.” Over time, however, all the cars became coaches. As the exclusivity of the term “coach” declined, it became associated with the cheap seats.

The Supermarine Spitfire is a British single-seat fighter aircraft which was used by the Royal Air Force and many other Allied countries throughout the Second World War. The Spitfire continued to be used as a front line fighter and in secondary roles into the 1950s. It was produced in greater numbers than any other British aircraft, and was the only British fighter in production throughout the war.

The Spitfire was designed as a short-range, high-performance interceptor aircraft by R. J. Mitchell, chief designer at Supermarine Aviation Works (since 1928 a subsidiary of Vickers-Armstrong). Mitchell continued to refine the design until his death from cancer in 1937, whereupon his colleague Joseph Smith became chief designer. The Spitfire’s elliptical wing had a thin cross-section, allowing a higher top speed than several contemporary fighters, including the Hawker Hurricane.[8] Speed was seen as essential to carry out the mission of home defence against enemy bombers.

During the Battle of Britain, the Spitfire was perceived by the public as the RAF fighter of the battle, whereas in fact, the more numerous Hurricane actually shouldered a greater proportion of the burden against the Luftwaffe. The Spitfire units did, however, have a lower attrition rate and a higher victory to loss ratio than those flying Hurricanes .

After the Battle of Britain, the Spitfire became the backbone of RAF Fighter Command, and saw action in the European, Mediterranean, Pacific and the South-East Asian theatres. Much loved by its pilots, the Spitfire served in several roles, including interceptor, photo-reconnaissance, fighter-bomber, carrier-based fighter, and trainer. It was built in many different variants, using several wing configurations. Although the original airframe was designed to be powered by a Rolls-Royce Merlin engine producing 1,030 hp (768 kW), it was adaptable enough to use increasingly more powerful Merlin and the later Rolls-Royce Griffon engines; the latter was eventually able to produce 2,035 hp (1,520 kW).