Very Rare
Very Rare
The height at which Jet planes fly Oxygen must be very rare , so how much Oxygen is required for combustion ?
At high altitudes the Oxygen level must be very low, still combustion is taking place , how is that possible on such a low Oxygen level ?
Oxygen does not get rare as you go up, it is about the same % of the air composition as at sea level. What happens, however, is that the pressure and the density go down as you go up. At the altitude a jetliner cruise (35000 ft or so), the density of the air is about 30% of what exists at sea level, but (and that is the neat part) this density is also a factor in the lift, which also depends on how much air one encounters to provide the pressure differential required to fly.
The solution? Fly faster. If you go faster, you encounter more air, and thus more oxygen, per unit time. This is actually the reason why airliner fly high: so they can fly faster.
Flying faster means you get enough air per unit of time to sustain combustion at a rate that is compatible with the thrust required to keep flying at that speed. Remember that any jet engine is made of 3 parts: a compressor at the front (that compresses air to actually a much higher pressure then what we have a sea level), a combustion chamber, and a turbine that extract some of the power from the hot gases to drive the compressor and accesories; the rest of the energy is propulsive power (I simplify; high bypass turbofan have most of their thrust coming from the by-pass air that only went through the low pressure compressor stage).
As you get further up, the requirement to fly faster still to get enough oxygen goes to above the speed of sound and eventually much higher; at such altitude an aircraft has to fly so fast and use so much energy, most engines run out of power (and you start having other problems, like kinetic heatic of the airframe). All those, and the fact that compression of the air around the speed of sound creates shock wave that take energy away, that wings may not be designed for, and so on; those considerations establish the ceiling of an airplane, the maximum altitude at which it can fly.
Just remember one thing: if you have less oxygen, say only 1/3 the amount, and you do no benefit from the high speed factor, you can still burn 1/3 as much fuel. That is what airplane do as well. Sure the thrust goes down, but as long as it is enough to balance drag, there is no need to accelerate or have excess power to climb, as the airplane is already at its peak altitude and speed.
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Coin collecting is not a specific age. It is something that is enjoyed by most people it does. Always good to have the coins that are considered "rare" and most of them do not even have a clue. Most people, who take this hobby seriously, tend to make a mistake in thinking that can never be as one of the professional coin collectors who boasts of holding the rarest coins that have ever been in circulation. All you need is to focus on the goal of making money in particular, will undoubtedly be a valuable asset.
There is one thing that should be mentioned here, do not consider the collection of rare coins from a specialty. You do not need all that coin collectors who specialize in collecting only coins that are rare or are in the category limited edition. The best collections that have been in existence are those that began with no special intention, or as a hobby. It is always lovely to hold coins rare, but the currencies of other regions and nationality may pep collection. It depends on you to choose the different ways you can save your coins. There are people who prefer that specializes in coins that belong to a particular season, or the coins that belong to a particular region.
Most of them have a problem getting started. Most beginners are curious about the rare coin, but are very apprehensive to get their hands on the rare collection. There are plenty of options when you decide to hands in the rare.
Most professionals in coin collecting, and the dealers are on the market undoubtedly help you get the rarest of coins that have been. Coin collectors, no doubt the rarity of the coin, they know with certainty, and not guided wrong, unless and until it engages with a crooked dealer. The next thing you need to take into account the considerations is cost. The coins are very expensive, though you beautiful in its collection, affording them the problem.
The next best thing to do to access these rare coins is to review Internet forums. Nothing escapes to the Internet. There are a lot of information and too many coins for sale on line itself. You may know the estimated price for a particular type of currency as well. Thus, the Internet is a great place to find what you need!
Most coin collectors are always aware of the coins they receive. They expect the currency, and when they find them, pounce on them. Many people are very rare coins at home, even without knowing they have a prized possession located on the platform with no one to praise its value. And, some people mistakenly give these currencies from traders. Therefore, always consider a coin before giving to anyone outside, for all you know, it is possible that holding a currency that can reach a million dollars.
Rare coins are very difficult to finding, which is exactly why they are called "rare", and whatever they know, they are just a few clicks away from you, and you have not yet understood. So keep your eyes open, and keep awake the inner collector, always!
About the Author:
Abhishek is an avid Coin Collecting enthusiast and he has got some great Coin Collecting Secrets up his sleeve! Download his FREE 58 Pages Ebook, "Understanding And Mastering The Art Of Coin Collecting!" from his website http://www.Fun-Galore.com/92/index.htm . Only limited Free Copies available.
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