Uhart-Mixe is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Urcuit
Urcuit is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Urdos
Urdos is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Urdès
Urdès is a commune in the Pyrénées-Atlantiques "department" in southwest France.
Urepel
Urepel is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Urost
Urost is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Urrugne
Urrugne is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Urt
Urt is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Ustaritz
Ustaritz is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Uzan, Pyrénées-Atlantiques
Uzan, Pyrénées-Atlantiques is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Uzein
Uzein is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Uzos
Uzos is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Verdets
Verdets is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Vialer
Vialer is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Viellenave-d'Arthez
Viellenave-d'Arthez is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Viellenave-de-Navarrenx
Viellenave-de-Navarrenx is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Vielleségure
Vielleségure is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Vignes, Pyrénées-Atlantiques
Vignes, Pyrénées-Atlantiques is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Villefranque, Pyrénées-Atlantiques
Villefranque, Pyrénées-Atlantiques is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Viodos-Abense-de-Bas
Viodos-Abense-de-Bas is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Viven
Viven is a commune of the Pyrénées-Atlantiques "département" in the southwestern part of France.
Caro, Pyrénées-Atlantiques
Caro, Pyrénées-Atlantiques is a commune in the Pyrénées-Atlantiques department in southwestern France.
Rocket engine
A rocket engine is a device that produces a force by pushing gases at high speed out of a nozzle. Rocket engines burn chemicals such as petroleum and liquid oxygen at very high pressures and temperatures to turn the chemical energy into motion. In some cases (such as NASA rockets), the force created can be over .
A garden hose shows how moving fluid can create a force. When a hose is turned up the hose will snake around unless it is held still. The exiting water is creating a force on the hose just like how the rocket engine gases push on the rocket engine.
Some rocket engines burn liquid fuels while some burn solid fuels. Solid fuel rocket engines are sometimes called "rocket motors".
Liquid fuel rocket engines often require complex pumps and valves to properly move (and pressurize) the liquids from the fuel tank to the actual engine. These machines must work in extreme temperatures and pressures. Liquid oxygen is very cold (-223˚C) while the engine is very hot (3000˚C), and the pressure is oftentimes hundreds of times higher than normal air pressure. Because of these conditions, liquid fuel rocket engines are often very complex and require very specialised materials (metals, ceramics, etc.).
Solid fuel rocket motors have the fuel (called propellant) as a solid mixture of an oxidizer and fuel. An oxidizer supports the burning of fuel much like oxygen supports burning. The common oxidizer is powdered Ammonium Perchlorate, while the common fuel is powdered aluminum metal. The two powders are stuck together with a third component known as the binder. The binder is a rubbery solid that also burns as a fuel. The simple idea makes solid rocket engines cheaper, but they cannot be turned off or controlled, and are more likely to explode than liquid rocket engines. Solid rockets also provide a smaller specific impulse, hence must be heavier to launch the same payload.
Military missiles commonly use solid rockets because they can be kept ready for many years. Many satellite launchers use solid rocket boosters when they start, but liquid rockets for the majority of the flight.
Hybrid rocket engines combine the two ideas. The two propellants are different states of matter, often with liquid oxidisers and solid fuels. They are not used much, but might be safer than solid rocket motors or liquid rocket motors
Nozzle
A nozzle is a device that takes incoming fluid (such as gas or liquid) and increases the speed. This is done by changing the size of the pipe (or tube) that the fluid is flowing through.
- Origine of the .
Penny Black
The Penny Black was the world's first adhesive postage stamp. It was issued by the United Kingdom on the 1 May 1840 and used from the 6 May the same year. All London post offices received official issues of the new stamps, but other offices in the country did not. Some post offices like in Bath, offered the stamp unofficially after 2 May.
Once the stamps were used, they had a red cancellation. However, it was hard to see, and it could easily be taken off. It is not very rare. The total print run was 286,700 sheets with 68,808,000 stamps. A mint condition stamp might fetch £3–4,000.
Penny Red
The Penny Red was a postage stamp issued in 1841 to replace the Penny Black. It was the main type of postage stamp in the United Kingdom until 1879. The design was hardly changed at all.
The colour was changed from black to red because it was hard to see the red cancellation mark on the Penny Black. It was easier to see a black cancelling on a Penny Red. It is not a very rare stamp.
Succession to the British throne
The line of succession to the British throne is the order in which members of the royal family would come to the throne if the reigning king or queen died.
At present the first in line is Charles, Prince of Wales, followed by his eldest son, Prince William, Duke of Cambridge and then Prince William's son, Prince George of Cambridge.
Traditionally, males came before females in the line of succession. However, the law changed on 26 March 2015, so at present, for people born after 28 October 2011 the succession is decided only by age: older children come before younger children. This system of inheritence is called absolute primogeniture, as opposed to male-preference primogeniture. When someone who is in line to the throne has a child, that child comes after them and their older children, but before anyone else in the line of succession.
Excluded from the line of succession are Catholics and illegitimate children.
No official, complete version of the line of succession is currently maintained. Any person's actual position in the line of succession may change when people are born or when they die. This list shows only those people who are descended from the sons of George V.
Two Penny Blue
The Two Penny Blue (or 2d Blue) was the world’s second official adhesive postage stamp. It was issued in the United Kingdom in May 1840. It was more or less the same as the Penny Black.
It was intended that the 2d blue was to be issued at the same time as the Penny Black. However the earliest post mark seen on a Two Penny Blue was the 8 May 1840 which is two days after the penny black was issued. The Two Penny Blue is much rarer and more expensive than the Penny Black.
Penny Lilac