history of airbus

Learning to Hover

2008-03-10T08:22:00.000-07:00

A big selling point of helicopters is that you can land in your backyard. Where then would be the best place to learn to hover? An airport with a 12,000' runway and a 7,500' crosswind runway. You want a lot of open space where you're guaranteed not to hit anything. You want somewhere that neighbors won't complain about the noise. You want somewhere with long sight lines to the horizon so that you won't concentrate your gaze in too close. You want somewhere that you can get fuel when you run out. All roads lead to the big airport! Generally the tower and ground controllers will give you permission to practice hovering on whichever runway isn't be used that day and/or over a seldom-used taxiway.

Most instructors will start by giving you one control at a time. You take the antitorque pedals and they handle the cyclic and collective pitch. You practice pedal turns. Then you take the collective while the instructor controls the cyclic and pedals. You go up, you go down. Maybe you land. Then you take the cyclic and the instructor takes the other controls and ... 1 second later the helicopter is oscillating like crazy and you hear "I have the controls" in your headset. Any good instructor will alert you to the fact that you need to be very light on the controls: "you fly with pressures, not movements." The instructor will also tell you that there is a bit of lag between the time that you put in a control input and the time that the helicopter reacts. What most instructors won't tell you is how to deal with these facts.

Here are a few tips for handling the cyclic, which controls forward/back and left/right movement of the helicopter:

Focus your gaze at least 1/2 mile in the distance if the sightlines in your practice area are long enough.
As soon as the helicopter is handed to you it will start to drift to the right. The tail rotor is counterbalancing engine torque but at the same time is pushing the machine to the right. Expect to hold a little bit of left pressure on the cyclic to avoid this translational drift.
Don't put in and hold a control input pressure. Suppose the helicopter is moving forward a bit. You press back on the cyclic and hold that pressure. One second later the helicopter has responded to the initial pressure by arresting its forward creep. One second after that the helicopter has responded to two seconds of continuous pressure by rushing backwards at a frightening clip. If the helo is moving forward, press backwards for a split-second then try to return the cyclic to a neutral position. See if the helicopter stops creeping. If so, great. If not, try another little stab of back pressure. Although every second or two you are doing something with the cyclic, in any given instant you need not be putting in any cyclic input. Nudge the cyclic and then return to center. Nudge and then return.
After an hour or two the instructor might be doing more harm than good in handling the other two controls. Everything is cross-coupled so if he is messing with the collective or the pedals it will require you to take action with the cyclic. It is actually easier to handle all three controls because at least the machine isn't doing completely unpredictable things from your point of view.
Take a break every 20 minutes by practicing takeoffs, trips around the pattern, and approaches to landings.

Why Flying a Helicopter is Hard

2008-03-10T08:21:00.000-07:00

Why do people have trouble flying a helicopter? Some don't! I taught a U.S. Navy airplane pilot to fly and hover a helicopter in about twenty minutes. At no time did he lose control of the machine, even hover taxiing back to the parking spot. Why did this guy have such an easy time? As an experienced jet and instrument pilot, he was very sensitive to changes in aircraft attitude. If the nose yawed very slightly to the left, he put in a slight right pedal pressure. If the nose dropped very slightly, he noticed the horizon moving and pulled back on the cyclic slightly.

What do folks who've never flown an aircraft before do? Sit there fat and happy while the attitude drifts a bit. Eventually the drift gets to the point that the helicopter is pointing 180 degrees from where it started or 45 degrees nose-up or 45 degrees nose-down and heading straight for the trees. At this point even a brand new pilot senses that something is amiss and it is time for a flight control input. A big one. The 45-degree nose-down attitude then turns into a 45-degree nose-up attitude.

The key in flying successfully and smoothly is to watch for small attitude changes and compensate with small control inputs. This is easier said than done, of course, and the instrument-rated airplane pilots have a big edge.

First Lesson: Air

2008-03-10T08:20:00.000-07:00

Before you get into the air you'll probably spend about half an hour on a preflight inspection of the helicopter. With most airplanes most of the critical pieces are hidden underneath bodywork and not accessible except to a mechanic during an oil change or 100-hour inspection. With the Robinson R22 the engine is mostly flapping in the breeze and what is hidden can easily be accessed via a flip-up door.

If the weather is nice you'll probably remove the doors. This ensures that you'll be nice and cool inside the machine. In theory you could look straight down while in flight and scare yourself but in practice your attention will be focussed on looking out the front and trying to hold the machine in a fixed attitude relative to the horizon. So don't hesitate to fly your very first lesson with the doors off. When the doors are off, it is good practice to take everything out of your pockets and put them in the baggage compartment underneath the seats. You don't want loose items getting sucked out of the helicopter and contacting the tail rotor, the fastest-rotating and most fragile part of the whole machine.

Sadly, a big part of your first lesson will be practicing the most difficult helicopter maneuver: hovering. Hardly anyone is able to become proficient at hovering in less than 5 or 6 hours of flight training. Every one of those hours is exhausting. Much of the time is frustrating.

First Lesson: Ground

2008-03-10T08:19:00.000-07:00

Because so many students have crashed R22s there are a bunch of special legal requirements associated with the aircraft. You aren't allowed to get into the machine at all until you've received and logged ground instruction.

The ground lesson is partly about energy management in the event of an engine failure and partly about not getting the helicopter into unusual attitudes.

As with airplanes, much of the key to safety in a helicopter is energy management. In an airplane you have potential energy (altitude) and kinetic energy (forward speed) that can be traded off against each other to bring the airplane down gently in the event of an engine failure or ordinary landing. The helicopter has three kinds of energy: potential (altitude), kinetic (forward speed), and angular momentum (blade speed).

In an airplane you can make decisions about trading forms of energy very late in the day. For example, if you pull the stick all the way back at 6000' above the ground you will gradually slow down and eventually stall and perhaps enter a spin. With many airplanes you could spin nearly all the way to the ground before applying forward stick and opposite rudder to get back to a normal flight condition. All without an engine.

In a helicopter, by contrast, if the blades spin down more than 10-15% from their normal velocity, there is no way to convert potential or kinetic energy into spinning such that the helicopter will start to fly again. If you can't restart your engine, therefore, your helicopter can very quickly become a rock.

In a turbine-powered helicopter like a Bell 206 JetRangers the blades are heavy and the blades won't slow down for several seconds after an engine failure. In the flyweight Robinson, however, after an engine failure you have no more than 1.2 seconds to take exactly the right actions or the helicopter cannot be recovered.

What if you do take all the right actions? Suppose that you're up at 4000' and the engine quits. You lower the collective pitch (lever on your left) immediately to flatten the blades and allow them to be driven by the wind through which the helicopter is now falling at 2000 feet-per-minute. You adjust the cyclic (stick in front of you) for about 65 knots of forward speed. You aim for a landing zone. The good news is that you don't need a very large one but the bad news is that the glide ratio is between 2:1 and 4:1 instead of an airplane's 10:1 and therefore you don't have as large an area from which to choose. As you get within about 50' from the ground you pull back the cyclic to flare the helicopter and shed most of the forward speed. Just as in an airplane this flare also arrests most of the vertical speed. At the second to last moment you stop flaring and return the helicopter to being parallel to the ground. Ideally at this point you are hovering 5' or so above a soccer field and the blades are still spinning. Finally you raise the collective as the helicopter falls, using the stored energy in the blades against the force of gravity. You land gently on the skids. (In practice the cyclic flare is more important than the "hovering autorotation" at the end; a lot of people walk away from helicopter engine failures if they get the cyclic flare right but can't manage to pull the collective smoothly at the last moment.)

This all sounds good until you look at the "deadman's curve". The marketing literature for helicopters says "if the engine fails, you can autorotate down to a smooth landing." The owner's manual, however, contains a little chart of flight conditions from which it is impossible to landing without at least bending the helicopter. Unfortunately these conditions are the very ones in which nearly all helicopters seem to operate. If you're above 500', for example, you're pretty safe. But TV station helicopters are often lower than that when filming. Flying along at 65 knots at any altitude is safe, but if the camera needs the pilot to hover the helicopter slows to a crawl and may get under the "height-velocity diagram", as the FAA calls the deadman's curve.

Choosing a Flight School and Instructor

2008-03-10T08:17:00.000-07:00

There are four ways to lose a flight: weather is unfavorably cloudy or windy, instructor is not available, helicopter is down for maintenance, helicopter has been scheduled by another student. If you are training at a school with only one helicopter and one instructor, the risk of being unable to fly is very high.


Helicopter

Look for a school with at least three training helicopters and two instructors.
Given that you don't know how to fly, how do you evaluate an instructor? The best instructors are relaxed and comfortable even as the student makes a lot of mistakes. The best instructors are able to talk a student through a maneuver rather than putting their hands on the controls and "demonstrating". Once you've learned how to hold a hover and fly straight-and-level, take at least one lesson with each instructor at your school and then pick the one whose style suits you best. You'll probably learn at least 50 percent faster with a really good instructor compared to an average instructor.

As a lower-time instructor myself, it pains me to say this, but I think that most of the really good instructors with whom I have flown had at least 800 hours [I wrote that sentence some years ago; now I have my 800 hours]. The low-time guys were often nervous and took the controls too readily. I have flown with one or two really high time instructors who were not so great; they could do amazing things with the helicopter but they weren't good at explaining to another person how to do those amazing things.

One strategy that you might pursue is to find a lower-time instructor who is a good explainer for the lower-risk maneuvers and then do the more challenging maneuvers with a high-time instructor. Maneuvers that demand a higher level of skill from the instructor include 180-degree autorotations, slope operations, throttle chops, and hover autorotations over anything other than a smooth paved surface.

Piston engines

2007-12-30T06:28:00.000-08:00

On the morning of Sunday, August 27, 1939, a gas turbine engine conceived by a young German physics student, Hans von Ohain, powered a Heinkel He 178 V1 on its first flight.

All previous aircraft had been powered by piston engines. Nearly every noteworthy aircraft performance improvement was the direct result of an engine improvement. Many of these engine improvements ranked among some of the greatest accomplishments of the first half of the Twentieth Century.

During the period between the World Wars, aircraft engines improved dramatically and made possible unprecedented progress in aircraft design. Engine development in those days, and to a large extent even today, is a very laborious, detailed process of building an engine, running it to destruction, analyzing what broke, designing a fix, and repeating the process. No product ever comes to market without some engineer(s) having spent many long, lonely, anxious hours perfecting that product. This is especially true of aircraft engines, which by their very nature push all the limits of ingenuity, materials, and manufacturing processes.

Just prior to World War II, engineers at both Pratt & Whitney and Curtiss-Wright worked feverishly to produce the first air-cooled engine capable of more than 2,000 horsepower. The efforts of both teams were nearly thwarted by severe vibration from unexpected sources. This is the story of how the Pratt & Whitney team, through hard labor and persistence, identified and solved the problems with vibration. The result was one of the most successful engines of all times - the R-2800.

Aviation fuel

2007-12-30T06:25:00.000-08:00

Aviation fuel is a specialized type of petroleum-based fuel used to power aircraft. It is generally of a higher quality than fuels used in less critical applications such as heating or road transport, and often contains additives to reduce the risk of icing or explosion due to high temperatures, amongst other properties.

Most aviation fuels available for aircraft are kinds of gasoline used in engines with spark plugs i.e. piston engines and Wankel rotaries or fuel for jet turbine engines which is also used in diesel aircraft engines. Alcohol, alcohol mixtures and other alternative fuels may be used experimentally but are not generally available.

Avgas is sold in much lower volumes, but to many more individual aircraft, whereas Jet Fuel is sold in high volumes to large aircraft operated typically by airlines, military and large corporate aircraft.

The Convention on International Civil Aviation, which came into effect in 1947, exempted air fuels from tax. Australia and the USA oppose a worldwide levy on aviation fuel, but a number of other countries have expressed interest.

Aviation fuel is often dispensed from a tanker or bowser which is driven up to parked aeroplanes and helicopters. Some airports have pumps similar to filling stations that aircraft must taxi up to. Some airports also have permanent piping to parking areas for large aircraft.

Regardless of the method, aviation fuel is transferred to an aircraft via one of two methods: overwing and underwing. Overwing fuelling is used on smaller planes, helicopters, and all piston-engine aircraft. Overwing fuelling is similar to automobile fuelling — one or more fuel ports are opened and fuel is pumped in with a conventional pump. Underwing fuelling, also called single-point, is used on larger aircraft and for jet fuel exclusively. For single-point fuelling, a high-pressure hose is attached and fuel is pumped in at up to 50 PSI. Since there is only one attachment point, fuel distribution between tanks is either automated or it is controlled from a control panel at the fueling point or in the cockpit. As well, a dead man's switch is used to control fuel flow.

Because of the danger of confusing the fuel types, a number of precautions are taken to distinguish between AvGas and Jet Fuel beyond clearly marking all containers, vehicles, and piping. AvGas is treated with either a red, green, or blue dye, and is dispensed from nozzles with a diameter of 40 millimetres (49 millimetres in the USA). The aperture on fuel tanks of piston-engined aircraft cannot be greater than 60 millimetres in diameter. Jet Fuel is clear to straw in colour, and is dispensed from a special nozzle called a "J spout" that has a rectangular opening larger than 60 millimetres in diameter so as not to fit into AvGas ports. However, some jet and turbine aircraft, such as some models of the Astar helicopter, have a fueling port too small for the J spout and thus require a smaller nozzle to be installed in order to be refuelled efficiently.

Any fuelling operation can be very dangerous, and aviation fuelling has a number of unique characteristics which must be accommodated. As an aircraft flies through the air, it can accumulate a charge of static electricity. If this is not dissipated before fuelling, an electric arc can occur which may ignite fuel vapours. To prevent this, aircraft are electrically bonded to the fuelling apparatus before fuelling begins, and are not disconnected until fuelling is complete. Some regions require that the aircraft and/or fuel truck be grounded as well.

Aviation fuel can cause severe environmental damage, and all fuelling vehicles must carry equipment to control fuel spills. In addition, fire extinguishers must be present at any fuelling operation, and airport firefighting forces are specially trained and equipped to handle aviation fuel fires and spills. Aviation fuel must be checked daily and before every flight for contaminants such as water or dirt.

Many airlines now require that safety belts be left unfastened should passengers be aboard when refuelling happens.

Flying boats

2007-12-16T10:16:00.000-08:00

A flying boat is a type of aircraft which uses its fuselage as a floating hull, generally stabilised on the water surface by underwing floats or stub projections. It is a specialised form of seaplane, an aircraft that is designed to take off and land on water utilising a carriage and pontoons that maintain the fuselage above water level.

Flying boats were among the largest aircraft of the first half of the 20th century. Their ability to alight on water allowed them to break free of the size constraints imposed by general lack of large, land-based runways, and also made them important for the rescue of downed pilots, a capability put to great use in world war II. Following World War II, their use gradually tailed off, with many of the roles taken over by land aircraft types. In the 21st century, flying boats maintain a few niche uses, such as for dropping water on forest fires and for air transport around archipelagos.

seaplanes

2007-12-10T10:00:00.000-08:00

A seaplane is a fixed-wing aircraft designed to take off and land (or "alight") upon water. Seaplanes can be divided into separate categories such as float planes, flying boats, and amphibious aircraft ("amphibians").

These aircraft are occasionally called hydroplanes, based on usage in several Romance languages, which is rare in english.

A floatplane has slender pontoons mounted under the fuselage. Two floats are common, but many floatplanes of World War II had a single float under the main fuselage and two small floats on the wings. Only the "floats" of a floatplane normally come into contact with water. The fuselage remains above water. Some small land aircraft can be modified to become float planes.
In a flying boat, the main source of buoyancy is the fuselage, which acts like a ship's hull in the water. Most flying boats have small floats mounted on their wings to keep them stable.

The term "seaplane" is used by some to refer only to floatplanes (aircraft with floats as landing gear), with the flying boat being a distinct type of craft. This article treats both flying boats and floatplanes as types of seaplane.

An amphibious aircraft can take off and land both on conventional runways and water. A true seaplane can only take off and land on water. There are amphibious flying boats and amphibious floatplanes, as well as some hybrid designs, e.g., floatplanes with retractable floats. Modern production seaplanes are largely amphibious and of a floatplane design.

In the post war period the availability of large paved runways and the greatly expanded performance of land based planes meant that both commercial and military use of seaplanes was much reduced. Anti-Submarine Warfare was just as easily carried out with land based aircraft, which often had better performance, and Search and Rescue could more easily be carried out with helicopters, which had the advantages of being operated from smaller ships, and in higher sea states. The compromises that came from being able to float and rise again from the water caused excessive drag and added considerably to the weight of the aircraft. In commercial service this translated into increased costs, and for a military aircraft, into reduced warloads, speeds and ranges.

Only in specialized roles were they able to remain competitive, such as waterbombing, where their ability to quickly reload was a huge asset. A number of surplus WW2 seaplanes including the Consolidated Catalina and Martin Mars were initially used in this role but their advancing age has required a new specially designed aircraft in the form of the Canadair Waterbomber which operates alongside an entire air force of second-hand land-based bombers and transports.

The only amphibian aircraft produced for post war commercial usage was the Grumman Mallard which was designed as a true airliner, with modern technology and longer ranges, greater passenger and cargo loads. The Mallard saw production from 1946-1951. Only 59 were delivered, used mostly by corporations and some regional commuter carriers.

Life Aboard the Space Shuttle

2007-12-07T22:41:00.000-08:00

orbiter must provide you with an environment similar to Earth. You must have air, food, water, and a comfortable temperature. The orbiter must also take away the wastes that your body produces (carbon dioxide, urine, feces) and protect you from fire. Let's look at these various aspects of the orbiter's life support system.

On board the space shuttle, you need to have the following:

atmosphere similar to Earth
carbon dioxide removed
contaminating or trace gases removed
normal humid environment

Our atmosphere is a mixture of gases (78 percent nitrogen, 21 percent oxygen, 1 percent other gases) at a pressure of 14 lbs/in² (1 atm) that we breathe in and out. The space shuttle must provide a similar atmosphere. To do this, the orbiter carries liquid oxygen and liquid nitrogen in two systems of pressurized tanks, which are located in the mid-fuselage (each system has two tanks for a total of four tanks). The cabin pressurization system combines the gases in the correct mixture at normal atmospheric pressure. While in orbit, only one oxygen-nitrogen system is used to pressurize the orbiter. During launch and landing, both systems of each gas are used.

Five loops of fans circulate the atmosphere. The circulated air picks up carbon dioxide, heat and moisture:

Chemical carbon dioxide canisters remove carbon dioxide by reacting it with lithium hydroxide. These canisters are located in the lower deck of the crew compartment and changed every 12 hours.
Filters and charcoal canisters remove trace odors, dust and volatile chemicals from leaks, spills and outgassing.
A cabin heat exchanger in the lower deck cools the air and condenses the moisture, which collects in a slurper. Water from the slurper is moved with air to a fan separator, which uses centrifugal force to separate water from air. The air is recirculated and the
water goes to a wastewater tank.

Besides air, water is the most important quantity aboard the orbiter. Water is made from liquid oxygen and hydrogen in the space shuttle's fuel cells (the fuel cells can make 25 lb (11 kg) of water per hour). The water passes through a hydrogen separator to eliminate any trapped hydrogen gas (excess hydrogen gas is dumped overboard). The water is then stored in four water storage tanks located in the lower deck. Each tank can hold 165 lb (75 kg). The water tanks are pressurized by nitrogen so that water can flow to the mid-deck for use by the crew. Drinkable water is then filtered to remove microbes and can be warmed or chilled through various heat exchangers depending upon the use (food preparation, consumption, personal hygiene). Excess water produced by the fuel cells gets routed to a wastewater tank and subsequently dumped overboard.

Outer space is an extremely cold environment and temperatures will vary drastically in different parts of the orbiter. You might think that heating the orbiter would be a problem. However, the electronic equipment generates more than enough heat for the ship. The problem is getting rid of the excess heat. So the temperature control system has to carry out two major functions:

Distribute heat where it is needed on the orbiter (mid-fuselage and aft sections) so that vital systems do not freeze in the cold of space.
Get rid of the excess heat.

To do this, the shuttle has two methods to handle temperature control:

Passive methods - generally simple, handle small heat loads and require little maintenance
- Insulating materials (blankets), surface coatings, paints - reduce heat loss through the walls of the various components just like your home insulation.
- Electrical heaters - use electrically-heated wires like a toaster to heat various areas.
Active methods - more complex, use fluid to handle large heat loads, require maintenance
- Cold plates - metal plates that collect heat by direct contact with equipment or conduction
- Heat exchangers - collect heat from equipment using fluid. The equipment radiates heat to a fluid (water, ammonia) which in turn passes heat on to freon. Both fluids are pumped and recirculated to remove heat.
- Pumps, lines, valves - transport the collected heat from one area to another.
- Radiators - located on the inside surfaces of the cargo bay doors that radiate the collected heat to outer space
- Flash evaporator/ammonia boilers - these devices are located in the aft fuselage and transfer heat from Freon coolant loops overboard when cargo bay doors are closed or when cargo bay radiators are overloaded.
  - Flash evaporator
    1. Freon coolant loops wrap around an inner core.
    2. The evaporator sprays water on the heated core.
    3. The water evaporates removing heat.
    4. The water vapor is vented overboard.
  - Ammonia boiler
    1. Freon coolant loops pass through a tank of pressurized ammonia.
    2. Heat released from the freon causes the ammonia to boil.
    3. Ammonia vapor is dumped overboard.

The cabin heat exchanger also controls the cabin temperature. It circulates cool water to remove excess heat (cabin air is also used to cool electronic equipment) and transfers this heat to a Freon exchanger. The Freon then transfers the heat to other orbiter systems (e.g., cryogenic gas tanks, hydraulic systems) and radiates excess heat to outer space.

The orbiter has internal fluorescent floodlights that illuminate the crew compartment. The orbiter has external floodlights to illuminate the cargo bay. Finally, the control panels are lighted internally for easy viewing.

Food is stored on the mid-deck of the crew compartment. Food comes in several forms (dehydrated, low moisture, heat-stabilized, irradiated, natural and fresh). The orbiter has a galley-style kitchen module along the wall next to the entry hatch, which is equipped with the following:

food storage compartments
food warmers
a food preparation area with warm and cold water outlets
metal trays so the food packages and utensils do not float away

Like any home, the orbiter must be kept clean, especially in space when floating dirt and debris could present a hazard. Wastes are made from cleaning, eating, work and personal hygiene. For general housecleaning, various wipes (wet, dry, fabric, detergent and disinfectant), detergents, and wet/dry vacuum cleaners are used to clean surfaces, filters and the astronauts. Trash is separated into wet trash bags and dry trash bags, and the wet trash is placed in an evaporator that will remove the water. All trash bags are stowed in the lower deck to be returned to Earth for disposal. Solid waste from the toilet is compacted, dried and stored in bags where it is returned to Earth for disposal (burning). Liquid waste from the toilet goes to the wastewater tank where it is dumped overboard.

Fire is one of the most dangerous hazards in space. The orbiter has a Fire Detection and Suppression Subsystem that consists of the following:

area smoke detectors on each deck
smoke detectors in each rack of electrical equipment
alarms and warning lights in each module
non-toxic portable fire extinguishers (carbon dioxide-based)
personal breathing apparatus - mask and oxygen bottle for each crew member

After a fire is extinguished, the atmosphere control system will filter the air to remove particulates and toxic substances.

History of the Space Shuttle

2007-12-07T22:38:00.000-08:00

Near the end of the Apollo space program, NASA officials were looking at the future of the American space program. They were using one-shot, disposable rockets. What they needed was a reliable, less expensive rocket, perhaps one that was reusable. The idea of a reusable "space shuttle" that could launch like a rocket but land like an airplane was appealing and would be a great technical achievement.

NASA began design, cost and engineering studies on a space shuttle and many aerospace companies also explored the concepts. In 1972, President Nixon announced that NASA would develop a reusable space shuttle or space transportation system (STS). NASA decided that the shuttle would consist of an orbiter attached to solid rocket boosters and an external fuel tank and awarded the prime contract to Rockwell International.

At that time, spacecraft used ablative heat shields that would burn away as the spacecraft re-entered the Earth's atmosphere. However, to be reusable, a different strategy would have to be used. The designers of the space shuttle came up with an idea to cover the space shuttle with many insulating ceramic tiles that could absorb the heat of re-entry without harming the astronauts.

Remember that the shuttle was to fly like a plane, more like a glider, when it landed. A working orbiter was built to test the aerodynamic design, but not to go into outer space. The orbiter was called the Enterprise after the "Star Trek" starship. The Enterprise flew numerous flight and landing tests, where it was launched from a Boeing 747 and glided to a landing at Edwards Air Force Base in California.

Finally, after many years of construction and testing (i.e. orbiter,main engines, external fuel tank, solid rocket boosters), the shuttle was ready to fly. Four shuttles were made (Columbia, Discovery, Atlantis, Challenger). The first flight was in 1981 with the space shuttle Columbia, piloted by astronauts John Young and Robert Crippen. Columbia performed well and the other shuttles soon made several successful flights.

In 1986, the shuttle Challenger exploded in flight and the entire crew was lost. NASA suspended the shuttle program for several years, while the reasons for the disaster were investigated and corrected. After several years, the space shuttle flew again and a new shuttle, Endeavour, was built to replace Challenger in the shuttle fleet.

In 2003, while re-entering the Earth's atmosphere, the shuttle Columbia broke up over the United States. NASA grounded the space shuttle program after the accident and worked feverishly to make changes and return the shuttles to flight. In 2006, the shuttle Discovery lost foam from its external fuel tank. Once again, the program was grounded and scientists struggled to solve the problem. The Discovery launched twice in 2006, once in July and again in December. According to NASA, the July 2006 launch was the most photographed shuttle mission in history. The Atlantis launched in September 2006, after delays due to weather, a problem with the fuel cell and a faulty sensor reading.

While the space shuttles are a great technological advance, they are limited as to how much payload they can take into orbit. The shuttles are not the heavy lift vehicles like the Saturn V or the Delta rockets. The shuttle cannot go to high altitude orbits or escape the Earth's gravitational field to travel to the Moon or Mars. NASA is currently exploring new concepts for launch vehicles that are capable of going to the Moon and Mars.

How Space Shuttles Work

2007-12-07T22:34:00.000-08:00

In its 26-year history, the space shuttle program has seen exhilarating highs and devastating lows. The fleet has taken astronauts on dozens of successful missions, resulting in immeasurable scientific gains. But this success has had a serious cost. In 1986, the Challenger exploded during launch. In 2003, the Columbia broke up during re-entry over Texas. Since the Columbia accident, the shuttles have been grounded pending redesigns to improve their safety. The 2005 shuttle Discovery was supposed to initiate the return to flight, but a large piece of insulating foam broke free from its external fuel tank, leaving scientists to solve the mystery and the program grounded once more until July 2006, when the Discovery and Atlantis both carried out successful missions.

In this article, we examine the monumental technology behind America's shuttle program, the mission it was designed to carry out, and the extraordinary efforts that NASA has made to return the shuttle to flight.

First, let's look at the parts of the space shuttle and a typical mission.

The space shuttle consists of the following major components:

two solid rocket boosters (SRB) - critical for the launch
external fuel tank (ET) - carries fuel for the launch
orbiter - carries astronauts and payload

A typical shuttle mission is as follows:

getting into orbit
- launch - the shuttle lifts off the launching pad
- ascent
- orbital maneuvering burn
orbit - life in space
re-entry
landing

A typical shuttle mission lasts seven to eight days, but can extend to as much as 14 days depending upon the objectives of the mission. Let's look at the stages of a mission one by one.

Military Aviation: Key Innovations

2007-12-05T03:17:00.000-08:00

While the Wrights may not have invented flight -- other powered aircraft had taken short hops before the Kitty Hawk flight of 1903 -- they certainly invented flying. Their master accomplishment was to develop the techniques for controlling an airplane: using a primitive wind tunnel of their own design, they calculated the forces that their Wright Flyer would have to overcome in order to stay airborne, and the means (a properly pitched propeller and wings that could be twisted to steer the plane) to do it.

Like the inventors of other groundbreaking military technologies, the Wrights were naively convinced that their invention would make war obsolete. Given the fact that airplanes could prevent surprise attacks, they believed no sane government would be willing to send its troops into battle.

The Rotary Engine

One of the biggest problems that early airplane designers had to overcome was the sheer weight of the available engines; heavy steel radiators and the water within severely hampered performance. In 1908, French engineers hit upon a solution: the rotary engine, which used spinning cylinders that were cooled by the passing air and didn't require liquid coolant. The first rotary airplane engine produced a then quite respectable 50 horsepower and was so comparatively small and light that it was named the Gnome.

Airborne Cameras

Once the German and Allied armies settled into great lines of trenches, and cavalry became useless in World War I, the airplane began to prove itself as an essential source of reconnaissance. At Neuve Chapelle in March 1915, the British based their battle plan on aerial surveillance and photographs. Early cameras were heavy and unwieldy; they took their images on glass plates, which were brought back to a mobile lab and developed. Taking airborne photos was one of the most dangerous jobs of the war; the airplane had to fly straight and level, presenting an easy target for ground fire.

Synchronized Machine Guns

As airplanes became armies' "eyes in the sky," the obvious question arose: How to blind the enemy? Early combat pilots tried shotguns, bombs, and fixed machine guns with little success. The easiest way to aim at another target was to point the entire airplane at it -- but how do you fire a machine gun from the front without shooting off your own propeller? The answer: synchronize the firing of the gun to the movement of the blades. In Anthony Fokker's original design, a series of pistons prevented the machine gun from firing when the blades were in front of it. When the system was mounted on the Fokker Eindecker, it was transformed into the first true fighter plane.
The Bomber

Although the idea of dropping bombs from above had existed for as long as military aircraft, the vision was thwarted by reality: bombs were heavy, and early aircraft were severely limited in the weight they could carry. But in 1914, Igor Sikorsky, a 20-year-old Russian designer, drew up plans for the first heavy bomber, with four engines and a 10-man crew. In 1917 the Germans followed suit with the Gotha, a massive plane inspired in part by Sikorsky's design. Gotha raids killed hundreds of Londoners, inflicted significant economic damage, and were an ominous harbinger of things to come.

The "Thick Wing" and the Monoplane

Ironically, the nation that lost the Great War pioneered the future of aviation even as they were being defeated. At the University of Gottingen, scientist Ludwig Prandl's and his team developed the science of aerodynamics and created the "thick wing," which gave planes the ability to climb at much steeper angles without losing lift and stalling. The thick wing also eliminated the need for a biplane, because it allowed engineers to mount the plane's structural reinforcements inside it. At the Schneider Trophy races of the 1920s and 1930s, the world's top designers unveiled monoplanes that were increasingly faster, more powerful, and more streamlined -- among them the precursor of the legendary Supermarine Spitfire.

Radar

At the beginning of World War II, after Germany had conquered France, the only thing standing between Hitler and complete domination of Western Europe was Britain's Royal Air Force. But the RAF had an invaluable tool: a new technology called radar, which used radio waves to detect the position of incoming aircraft. Atmospheric scientist Robert Watson Watt developed the British system, and although seven other countries developed radar simultaneously during the 1930s, the British had the most urgent need for it and were the first to put it to use in an early warning network called Chain Home. The network gave the British priceless advance warning of German air raids, and allowed them to concentrate their outnumbered fighters at critical locations. On December 7, 1941, an American radar station detected the Japanese planes approaching Pearl Harbor, but the U.S. military had little faith in the system and mistakenly assumed the signal came from a formation of American B-17s.

HOW FLIGHT WORKS

2007-12-05T03:04:00.000-08:00

Take-off

Take-off is the first step towards flying the aircraft. In order for a jet aircraft to take-off, it must first release its wheel brakes. The second step is powering up the engine to maximum speed to start moving down the runway. Once the aircraft has reached a decent take-off speed, usually 100 to 200 miles an hour depending on the type of aircraft, the pilot will pull back on the control device causing the elevators to shift upwards. This causes the airflow to push on the top of the elevators and force the back of the wing down causing the aircraft to lift off the runway nose first. Now that the takeoff is complete we move to the phase of flight, elevation.

Elevation

Elevation is the process of an aircraft increasing its altitude. This is what makes it possible for the aircraft to increase its altitude to maintain a level line of flight. Once the plane has taken off, the pilot must make the aircraft climb in order to reach crusing altitude. Like before, in the take-off, the pilot will pull back on the control device to start the climb. The elevators will again go up, and the flow of the air will push the aircraft upwards. Continuing this procedure, the pilot will keep climbing until he or she has reached the cruising altitude suitable for the type of aircraft. Now that we have reached our cruising altitude, let's investigate why we are moving so smoothly through the air.

Bernoulli's principal

The following information came from a man named Bernoulli who developed a theory about flight in the mid 1700's. This principle stated that lift, the force that supports an aircraft, is generated by different pressure over the top and bottom of the wing. The air that flows over the curved wing of an airplane has a longer distance to travel than the air flowing under the wing. The air on the top of the wing has to travel faster because of the increased distance, thus creating a lower pressure. On the other hand, the air that is traveling on the under side of the wing is traveling slower so it creates a higher pressure. With the lower pressure on the under side, and the higher pressure on the top side, you get a combination that produces lift which keeps the airplane flying. With a better understanding of how flight works, let's move to the next phase, controls.

Controls

Ailerons The ailerons are located on the back of both aircraft wings. The ailerons are controlled by moving the control device to the right or left. When the control device is to the left, the right aileron will be shifted upwards and the left aileron will be shifted downwards. This will cause the aircraft to rotate around its horizontal axis to the left.
Elevators An aircraft's elevators are located on the two horizontal fins on the back of the plane. They are controlled by moving the control device forward and backwards. When the control device is pulled back the elevators both shift upwards causing the plane to climb and vice versa.
Rudder An aircraft's rudder or rudders are located on the vertical tail fins. Each tail fin has one rudder. The rudder is controlled by the aircrafts rudder pedals located on the floor of the cockpit. There are two pedals and each one turns the rudder a different way. If the pilot pushes down of the right rudder pedal the rudder will shift to the right side causing the plane to yaw, or "slide", to the right along its vertical axis.

When all three of these controls are used simultaneously, the aircraft will turn and climb or dive very smoothly. No one control dominates another and an aircraft must have all three in order to fly

Antonov An-225 :The World's Biggest Plane

2007-12-05T02:56:00.000-08:00

There is nothing on Earth or in the air quite like the Antonov An-225. Dwarfing a Boeing 747 and out-lifting a U.S. Air Force C-5A Galaxy, it can haul an expeditionary force into combat, or carry enough food to avert a famine. Yet, oddly, the original purpose of the An-225 was neither hostile nor humanitarian. Conceived in the chilliest years of the Cold War, the plane was designed as an airborne tow truck for the now-defunct Soviet space shuttle program. Despite its lack of armaments, NATO war planners gave the An-225 a military code name, Cossack. History would reveal that the Soviet nickname for the An-225, Mriya, which is Ukrainian for "dream," was more apt.

In keeping with the Soviet penchant for building the world's biggest everything, the An-225 was designed to carry twice as much as a Boeing 747 freighter. The dimensions of the An-225 are staggering--nearly a football field from nose to tail and wingtip to wingtip. With a maximum takeoff weight of about 1.32 million pounds, it is 50 percent heavier than a fully loaded C-5A. To get so massive an aircraft into the sky, Ukrainian engineers equipped the An-225 with six ZMKB Progress Lotarev D-18T turbofan jets, each capable of pumping out 51,590 pounds of thrust.

After only 3-1/2 years in development, Mriya took its maiden voyage on Dec. 21, 1988. Less than a year later the Berlin Wall fell, and with its collapse the Soviet Union dissolved. Ukraine, home to the Antonov Design Bureau that created the An-225, split away as an independent republic. And with these changes the future of the An-225 changed as well.

Military Roots
As revolutionary as it appears, the An-225 is a derived rather than original aircraft. Basically, it is an enlarged version of the Antonov An-124 military transport. Engineers stretched this smaller plane nearly 40 ft. and added two engines. To distribute the weight of the fully loaded, 6-engine aircraft, the An-225 was equipped with an unusually configured 32-wheel landing gear. Normally, only the nose gear of an aircraft is steerable. On the An-225 there are 20 steerable wheels: four in the nose gear and 16 at the rear of the 28-wheel main gear. The result is an aircraft that is extremely maneuverable.

Making the An-225 equally agile in the air is the reason behind the plane's signature wide split-tail. While most of the An-225 follows the lines of the smaller An-124, the modified split-tail was added to maintain the plane's maneuverability when it carries large exterior loads.

Arriving In Style
The An-225 made its international debut in a style befitting its dimensions: by landing at the 1989 Paris Air Show with the Buran space shuttle on its back. Eight months earlier, on Nov. 15, 1988, the Soviet shuttle made history in its own right, with its one and only orbital flight, an unmanned mission in which it circled the Earth twice. Despite this success, the shuttle program was grounded for lack of funds, and formally discontinued in 1993. Without a mission, the need for the An-225 evaporated. The massive plane was parked outside its hangar near Kiev, its engines scavenged for parts.

With the breakup of the Soviet Union, the Antonov Group acquired the An-225 and began searching for a way to make the plane profitable. The An-225 boasts a payload of 551,150 pounds. What cannot fit inside can be put on its back. Objects as large as 33 ft. in diameter and 230 ft. long can be accommodated. Plus, it offers exceptional speed and range: The big jet cruises at nearly 500 mph and, fully loaded, it could fly nonstop from New York to Los Angeles. Armed with these impressive credentials, the Antonov Group found a business partner, Motor-Sich, the Ukrainian manufacturer that built the plane's engines. Together they invested the equivalent of $20 million to repair the An-225 and install modern avionics.

The first hint that the investment might pay off came on Jan. 2, 2002. The plane took off from Stuttgart, Germany, on its first commercial flight, hauling 216,000 prepared meals for American military personnel in the Persian Gulf. "Bookings range from general cargo to items of over 200 tons and pieces that would only fit on the roof," says a spokesman for Air Foyle HeavyLift, the company that hopes to put the An-225 into regular service.

There is an outside chance that an An-225 will play a role in the Russian space program, as a flying first stage of the proposed MAKS Space Plane, which could fly as early as 2006.

Meanwhile, the status of the An-225 is being challenged by the new Airbus A-380. Scheduled to fly in 2006, it boasts a takeoff weight of 1,235,000 pounds, a shade lighter than the An-225.

PEARL HARBOUR

2007-12-03T10:16:00.000-08:00

Pearl Harbor Raid, 7 December 1941 --
Overview and Special Image Selection

The 7 December 1941 Japanese raid on Pearl Harbor was one of the great defining moments in history. A single carefully-planned and well-executed stroke removed the United States Navy's battleship force as a possible threat to the Japanese Empire's southward expansion. America, unprepared and now considerably weakened, was abruptly brought into the Second World War as a full combatant.

Eighteen months earlier, President Franklin D. Roosevelt had transferred the United States Fleet to Pearl Harbor as a presumed deterrent to Japanese agression. The Japanese military, deeply engaged in the seemingly endless war it had started against China in mid-1937, badly needed oil and other raw materials. Commercial access to these was gradually curtailed as the conquests continued. In July 1941 the Western powers effectively halted trade with Japan. From then on, as the desperate Japanese schemed to seize the oil and mineral-rich East Indies and Southeast Asia, a Pacific war was virtually inevitable.

By late November 1941, with peace negotiations clearly approaching an end, informed U.S. officials (and they were well-informed, they believed, through an ability to read Japan's diplomatic codes) fully expected a Japanese attack into the Indies, Malaya and probably the Philippines. Completely unanticipated was the prospect that Japan would attack east, as well.

The U.S. Fleet's Pearl Harbor base was reachable by an aircraft carrier force, and the Japanese Navy secretly sent one across the Pacific with greater aerial striking power than had ever been seen on the World's oceans. Its planes hit just before 8AM on 7 December. Within a short time five of eight battleships at Pearl Harbor were sunk or sinking, with the rest damaged. Several other ships and most Hawaii-based combat planes were also knocked out and over 2400 Americans were dead. Soon after, Japanese planes eliminated much of the American air force in the Philippines, and a Japanese Army was ashore in Malaya.

These great Japanese successes, achieved without prior diplomatic formalities, shocked and enraged the previously divided American people into a level of purposeful unity hardly seen before or since. For the next five months, until the Battle of the Coral Sea in early May, Japan's far-reaching offensives proceeded untroubled by fruitful opposition. American and Allied morale suffered accordingly. Under normal political circumstances, an accomodation might have been considered.

However, the memory of the "sneak attack" on Pearl Harbor fueled a determination to fight on. Once the Battle of Midway in early June 1942 had eliminated much of Japan's striking power, that same memory stoked a relentless war to reverse her conquests and remove her, and her German and Italian allies, as future threats to World peace

The wrecked destroyers USS Downes (DD-375) and USS Cassin (DD-372) in Drydock One at the Pearl Harbor Navy Yard, soon after the end of the Japanese air attack. Cassin has capsized against Downes.
USS Pennsylvania (BB-38) is astern, occupying the rest of the drydock. The torpedo-damaged cruiser USS Helena (CL-50) is in the right distance, beyond the crane. Visible in the center distance is the capsized USS Oklahoma (BB-37), with USS Maryland (BB-46) alongside. Smoke is from the sunken and burning USS Arizona (BB-39), out of view behind Pennsylvania. USS California (BB-44) is partially visible at the extreme left.
This image has been attributed to Navy Photographer's Mate Harold Fawcett.

USS Maryland (BB-46) alongside the capsized USS Oklahoma (BB-37).
USS West Virginia (BB-48) is burning in the background.

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Sailors in a motor launch rescue a survivor from the water alongside the sunken USS West Virginia (BB-48) during or shortly after the Japanese air raid on Pearl Harbor.
USS Tennessee (BB-43) is inboard of the sunken battleship.
Note extensive distortion of West Virginia's lower midships superstructure, caused by torpedoes that exploded below that location.
Also note 5"/25 gun, still partially covered with canvas, boat crane swung outboard and empty boat cradles near the smokestacks, and base of radar antenna atop West Virginia's foremast.

history

2007-12-02T11:07:00.003-08:00

The ease with which birds roam the skies has always been envied by man. The dream to be able to take off to the skies is probably as old as mankind itself. However, the concept of the aeroplane or airplane is fairly new.

Just about 2 centuries ago man tried imitating birds by creating the omithopter. The omithopter was basically a machine with flapping wings. Unfortunately, it did not scale well. Flapping wings were great to lift light bodied birds. However, they simply did not have the power required to lift an entire machine and a human body as well. The concept was good but could not be executed.

In around 1783, another attempt at flying was made by a few daring aeronauts in lighter-than-air balloons. While this experiment succeeded in getting off the ground – literally – it did not go very far either. The aeronauts had no way to maneuver the balloon and were completely dependent on the strength and direction of the wind for their flight. The project was grounded soon after.

It was only in 1799, that an Englishman named Sir George Cayley built the first true airplane. He conceptualized a flying machine that had fixed wings instead of flapping ones, a propulsion system and even movable control surfaces. Thus, the fundamental concept of airplanes came into existence.

With his emphasis on lift, thrust and control Cayley designed the first glider in 1804. It had a single wing and a movable tail mounted on a universal joint. It also had an adjustable center of gravity and was the first ever aircraft of any size capable of flying. In 1809 Cayley expanded the glider concept and built a man-sized one with wings spanning 300 feet. A few hops were all it could manage. Around the same time Cayley also published a three part series ‘On Aerial Navigation’ in Nicholson’s Journal Of Natural Philosophy to propound his theory on flying as being a consequence of lift, propulsion and control.

While Cayley was working on his glider there were others too who were trying to fly. In 1831 Thomas Walker proposed the tandem-wing design airplane. It featured a wing whose camber was upside down. Had it been built it would have stayed firmly on the ground. In 1843 Samuel Henson proposed the first ever design for a propeller driven fixed-wing aircraft. A few years later Henson built his airplane with Stringfellow but it only managed brief glides.

It was after years of experimentation and research in 1849, that Cayley finally built a small glider that could lift about 80 pounds of weight. He called it the ‘boy-glider’ since it could lift a 10-year old boy for a few yards. And what followed changed the course of flying forever. In 1853, Cayley built an improved version of the boy-glider and convinced his coachman to pilot it. The coachman made a wavering and uncontrolled glide of a few hundred feet. This was the first ever truly manned flight in a fixed wing aircraft!

Soon after attempts started being made by others as well to build power aircrafts. In 1857 Felix Du Temple and his brother Louis flew a model monoplane with steam engine driven propellers. This was the first ever, successful flying powered aircraft.

In 1871, Penaud built the planophore. It was a 20-inch long monoplane with a pusher propeller powered by a rubber band and flew 131 feet in 11 seconds. Wenham and Browning in the same year demonstrated the wind tunnel to prove that cambered wings produce more lift than other types of wings. There were continued attempts by many inventors to build successful powered aircrafts. While many important discoveries were made, no one was able to build an aircraft capable of sustained flight.

In the last two decades of the nineteenth century many discoveries and attempts were made to build an airplane. Moulliard of France pointed out the necessity of training pilots to fly the various aircrafts being built. Parsons in England used a small steam engine to propel a plane for almost 300 feet. This is the first ever account of a jet aircraft.

In 1884 a significant discovery was made by Horatio Philips. He worked with cambered wings in a wind tunnel, which is the scientific foundation for modern airfoil designs as well. He also discovered that when wind blows across a curved surface, it creates a low pressure area on top of the surface and high pressure area below it. This is what generates the much-required lift.

In 1891 Samuel Langley began experimenting with Aerodromes and even got funding from the government. The first five attempts however, were all miserable failures.

And finally, it was around the same time, the Wright brothers start building their airplane and getting recognized for their work at Kitty Hawk. The story of the Wright brothers’ airplane reads like a true American success story! All the above events seem to be leading up to the grand finale executed and performed by Orville and Wilbur Wright.

history

2007-12-02T11:07:00.001-08:00

history of aeroplanes

2007-12-02T11:02:00.000-08:00

History

There have been many pioneers in the history of aeroplanes but the first to successfully fly an aeroplane were the Wright Brothers, Orville and Wilbur. Orville and Wilbur were skilled craftsmen and keen experimenters. They owned a business making and repairing bicycles. They were able to bring the value of a scientific approach to the invention of a heavier-than-air machine.

On the 17^th of December 1903 they were successful in producing the world's first powered flight. Wilbur ran alongside the plane, Flyer, as Orville took off on the sand dunes outside a town called Kitty Hawk in North Carolina, USA. The flight lasted just 12 seconds and travelled 37 metres. This distance is less than the wingspan of a modern airliner, but it was a major accomplishment at the time.

The brothers received very little recognition in their home country. People were very sceptical about their achievement. On the 8^th of October 1908, Wilbur flew their famous plane, Flyer, in front of a large crowd in France. The next day it was all over the French newspapers.

Orville and Wilbur Wright

Why Do Aeroplanes Fly?

Aeroplanes planes are able to fly due to differences in air pressure. When a plane is on the ground, not moving, the pressure around it is the same top and bottom. The downward pressure of gravity is the same as the upward pressure of the ground. The plane has no lift.

A plane on the ground.

The shape of the wing gives the aeroplane the ability to lift of the ground. The wings are more curved on top than they are the bottom. As the wings move through the air, the air that travels over the top of the wings has further to move than the air travelling below. Air that moves faster has lower air pressure than air that moves slower. This means that there is lower air pressure above the wing than below. The result is an upward force or pressure and the plane is able to lift.

A cross section of a wing with air moving over it.

A plane is able to move forward because of the engine powered propellor. As it starts to move forward, the air pressure on the plane starts to change as the air moves over the wings. The upward pressure is now greater than the downward pressure of gravity and the plane starts to lift of the ground and is able to fly.

The principle of 'lift'.

history of airbus

Learning to Hover

Why Flying a Helicopter is Hard

First Lesson: Air

First Lesson: Ground

Choosing a Flight School and Instructor

Piston engines

Aviation fuel

Flying boats

seaplanes

Life Aboard the Space Shuttle

History of the Space Shuttle

How Space Shuttles Work

Military Aviation: Key Innovations

HOW FLIGHT WORKS

Antonov An-225 :The World's Biggest Plane

PEARL HARBOUR

Pearl Harbor Raid, 7 December 1941 --Overview and Special Image Selection

history

history

history of aeroplanes

Pearl Harbor Raid, 7 December 1941 --
Overview and Special Image Selection