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Short History Of The Hovercraft

A hovercraft is a vehicle supported on a cushion of air supplied by a powered fan mounted on the craft. Hovercraft SK-5The hovercraft was invented by Christopher Cockerell in 1956. The theory behind one of the most successful inventions of the 20th century, the Hovercraft, was originally tested in 1955 using an empty KiteKat cat food tin inside a coffee tin, an industrial air blower and a pair of kitchen scales. Sir Christopher Cockerell developed the first practical hovercraft designs, these led to the first hovercraft to be produced commercially, the SRN1.



Christopher Cockerell's idea was to build a vehicle that would move over the water's surface, floating on a layer of air. This would reduce friction between the water and vehicle. To test his hypothesis, he put one a smaller can inside a larger can and used a hairdryer to blow air into them. The downward thrust produced was greater when one can was inside the other rather than air just being blown into one can.

Christopher Cockerell - Biography (information provided by NASA)

Christopher Sydney Cockerell was born in 1910. He worked for the Radio Research Company until 1935 and then for the Marconi Wireless Telegraph Company from 1935 until 1951. During the war years, Christopher Cockerell worked with an elite team at Marconi to develop radar, a development which Churchill believed had a significant effect on the outcome of the Second World War, and Cockerell believed to be one of his greatest achievements. While at Marconi, Christopher Cockerell patented 36 of his ideas. Christopher Cockerell was knighted for his achievement in 1969.

Power-to-weight-to-strength - The hull of the hovercraft

The next consideration for a properly functioning hovercraft is the power-to-weight-to-strength ratio, which affects lift, propulsion and handling as well.This deals with the structural strength of the raft to be light enough to be lifted by the air cushion created underneath, yet strong enough to carry the weight of the engine, its passengers or payload. More information can be found on this site http://leisure-hovercraft.com

Air cushion vehicle hull construction is more closely based on aviation rather than marine constructions for the simple reason that aviation hulls are a combination of strength and lightness as opposed to strength as a priority. Although wood and plywood are often used, many hovercraft hull structures are made of aluminum (aluminium) skin, welded or riveted onto an aluminum web or frame. Enclosed spaces are sealed to provide airtight compartments for natural buoyancy.

Finding The Right Used Audi For Sale

If you're buying a used vehicle, an Audi is an excellent choice. These cars are known for their durability. Even if the one you buy has been driven extensively, you should be able to rely on it for a number of years to come.

With that said, you're still going to want to make sure you find the best car for your needs. Here are a few of the things you should try to keep in mind as you look for a used Audi for sale.

It's Smart To Buy From A Dealership

Although you can find a number of excellent deals when looking at cars sold by private sellers, in the long run, going to a professional car dealer is your best bet. You'll have a lot more security, and you'll find that you have more options as well.

When you buy your car from a private seller, you may not have any recourse if the car stops working a few weeks or months down the road. If you have a problem with a car that you bought from a dealer, you can take it in, and they'll take care of the problem for you. That kind of service is worth paying a little more for.

Make Sure You Choose The Right Dealership

While buying a car from a dealer is generally the more secure option, there are some dealers that are much better than others. Try to find a dealer that has a lot of positive reviews from customers.

You may want to talk to your friends and family members to find out if there's a dealership in the area you recommend. You can also read reviews of local dealers online. You should be able to find a lot of information there that'll help you in your search.

Do Your Research First

The more you know about what it is you're going to buy, the easier it will be for you to get a good deal. If you know you want an Audi, you'll want to read up on the different makes and models of Audis. Find out which ones have received a lot of positive feedback, and which ones have problems.

It's also important to make sure you know what sort of prices are reasonable for used Audis. Check the listed value for the kind of cars that you're considering. When you go look at cars, make sure that the price seems fair.

Test Drive The Car

You don't want to buy a car unless you've had a chance to see how it drives! Make sure you get a chance to test drive your Audi before you make your purchase. Don't go out on a rushed test drive; try to drive it until you're satisfied.

It's easy to find a used Audi for sale, but you want to make sure you find the right vehicle for you. Take a look at all your options, and don't make a purchase until you find a car you love.



Problems Associated With Leisure Hovercraft

On the face of it, a hovercraft has a simple principle - simply provide a pressurized cushion of air underneath the hull, contain it with a skirt attached to the periphery of the hull and it will fly. As with most things in life, it's never as easy as all that. There are many things that hovercraft design needs to take into account, both in terms of safety and practicalities. Assuming that we have a good theoretical design and a working prototype machine, what are the practical tests required to ensure correct operation in all conditions?

An air cushioned craft can lift off from two basic types of surface either dry or wet. The thrust power required to lift off from the two are just not the same. In fact, it takes more power to lift a craft from the surface of a river, lake or the sea than it does from dry land, ice or any other solid surface. Lifting off from water is known as 'getting over the hump' and is a particular problem for hovercraft designers. The power to weight ratio is important and unfortunately an engine needs to be designed with extra capacity to give up to 25% more power than needed for normal flight, just to lift off from a wet surface if needed.

A low powered vehicle may have difficulty lifting off from water, but this is generally an inconvenience. Lightening the load a little will ensure lift off and it's not a safety issue unless you happen to be stranded miles out to sea. However, there is one feature that is potentially hazardous and this is called 'Plow-In'. When an ACV is moving at full speed over the sea, or other turbulent water, the surface may not always be flat. On the sea, waves are an important factor for smooth hovercraft flight. Similarly over river rapids, the same principles apply. Actually, the problem on river rapids is probably more acute because rocks may be jutting up or just below the surface of the water.

On the sea, it's common for a wave to rise up and strike the bow of a small boat or hovercraft. A boat will simply bounce over the top of it, but in the case of an ACV this can have disastrous effect. Hovercraft design is crucial - if not designed correctly, the wave will cause the front to dip into the water, which is called 'Plow-In'. The bow plows into the water, raising the stern and coming to a very abrupt stop. This is obviously a major safety concern, as any passengers will be thrown violently into the sea, or come into contact with the craft causing injury.

A Brief History Of The Agm Battery.

AGM battery technology was first developed in the 1980s by Concorde aircraft battery. They were looking for a cheaper alternative to the NI-Cad batteries that were used in fighter jets and naval helicopters. The batteries were designed to be vibration resistant.

AGM stand for Absorbed Glass Mat. The batteries have lead plates within them. The electrolyte is absorbed into finely woven Boron-Silicate glass fibre mats. The saturated mats are placed between the plates.

AGM batteries are very similar to flooded lead acid batteries but the only difference is that they hold the electrolyte inside a glass mat instead of allowing it flood freely over the plates. Therefore, you will not lose any electrolyte if the battery is turned over or held upside down.

Because the batteries were developed for military use, they can take much more abuse than standard deep cycle gel batteries or wet cell. Therefore, there is nothing to spill or leak and they are free from freezing damage.

AGM batteries can be stored in areas considered to be prohibited because there are no fumes or leakage. Another major advantage is that they can be stored on end or on their sides if need be without any damage.

The battery is constructed in such a way that the electrolyte is close to the active plate material. This makes charge cycles and discharge more efficient. Because of this and because of the fact that the internal resistance of the battery is very low they charge at a faster rate and to a higher capacity.

Because an AGM battery has a low discharged rate when stored for longer periods of time, they can quickly be recharged back to over 95% of their capacity provided they have not been left for too long in a discharged for a very longer period of time.

AGM batteries have a charging rate of up to 75% of their rated ampere hour capacity. This may lead to damaged standard auto chargers or alternators since they are susceptible to excessive heat generated when trying to deliver the maximum amps.

The good part is the fact that AGM batteries will charge at lesser rates. However, if you are going to spend money on a quality battery, it is a good idea to buy a quality three-stage charger.

An AGM battery can be used for many different functions. They can be used in deep cycle applications, as starting batteries or as standby batteries for critical powered systems. These roles make the batteries ideal for camping applications.



ABriefHistoryOfTheAgmBattery