FIXED BODY AXES SYSTEM FOR AIRPLANES

AIRFOILS

WING CHARACTERISTICS

AERODYNAMIC FORCES

FORCES

1-FORCES DUE TO GRAVITY

2-FLUID STATIC AND DYNAMIC FORCES

3-PROPULSION FORCES

What's Different About Taildraggers?

What makes a taildragger different from an airplane with tricycle gear? There really is only one simple difference. The center of gravity is forward of the main gear on the tricycle gear airplane and behind the main gear of the taildragger. This one little difference accounts for some pretty significant differences in the way the airplanes behave while on the ground and during takeoff and landing.

Taxiing

The first difference you would notice comes during taxiing. Since the center of gravity is behind the taildragger's main landing gear, the airplane does not want to go straight. The tail wants to come around and go in front of you because the center of gravity is pushing from behind. When you push something, it's tricky to keep it going straight. Since the tricycle gear airplane's center of gravity is forward of the main landing gear, it acts to pull the airplane behind it. When you pull something, it comes along nice and straight behind you.

A good analogy can be made with one of those carry-on pieces of luggage everyone seems to have these days with two wheels on it and a pull out handle. If you pull it behind you it rolls straight along. This is the principle of the tricycle gear airplane at work. If you try to push it out in front of you, the principles of the taildragger are at hand and it's a different animal. You really have to pay attention and be quick to keep it out there in front of you. It constantly wants to go to either side and swing around behind you. The further off-center you let it get, the more difficult it is to get it straight again. If you let it get too far off center it's too late. It's sideways and you cannot get it back in front of you. If you have a piece of luggage like this, give it a try. You will get an excellent feel of the forces affecting the ground handling of a taildragger.

This is really the exact same physics at work as trying to balance a baseball bat standing straight up on the palm of your hand, with the grip end up in the air. It's not quite that quick in the airplane because most taildraggers have a much wider wheelbase to length ratio than a baseball bat. The taildragger's center of gravity is much closer to its main gear than the baseball bat's is to its tip, but this analogy really brings the point home. As long as you pay attention you can keep that bat balanced up there, but let your attention wonder just for a moment and the bat might start to fall. More than likely it will get too far over to save. You will soon run out of arm movement necessary to get back under the balance point, which would be like running out of brake power, rudder, and runway in the taildragger.

Takeoff

The next difference you will notice comes during takeoff. With a tricycle gear airplane, you accelerate down the runway, the airplane pretty much rolling straight on its own, until you reach a desired speed, at which time you simply pull back on the wheel and lift off. Takeoffs in a taildragger require a lot more work. Predominantly, right rudder will be required to keep the airplane rolling straight down the runway, but constant rudder corrections are necessary to keep it rolling absolutely straight. With the tailwheel on the ground, most taildraggers are rolling down the runway right at the stall angle of attack. This is by design for landing purposes. The normal takeoff procedure is to raise the tail just a little to the proper angle of attack for the airplane to fly itself off the ground. When the tail comes up, you lose the traction of the tailwheel, so a little more right rudder is required to keep it going straight. Also, there is a law of physics that says when the plane of a gyro is tilted, it reacts with an opposite force 90 degrees in the direction of rotation. Well, it turns out that the propeller is a pretty good gyro. When the tail comes up, you are tilting the plane of the propeller. The force you are applying is the equivalent of pushing at the top of the propeller arc from behind. Since the propeller is rotating clockwise when viewed from behind, the gyroscopic reaction comes as if it were pushing on the airplane's right side of the propeller arc. This tends to turn the airplane to its left while the tail is actually moving up. So, while the tail is moving up, an extra dose of right rudder is required. A good taildragger pilot leads with a little extra right rudder an instant before the tail starts up to keep the nose aligned perfectly straight, rather than waiting for it to start left and then apply the correction. Also know that the more horsepower the engine has, the stronger this gyroscopic reaction is, as well as torque, so more right rudder will be required. In some really powerful airplanes, you would not have enough rudder to counteract these forces, so power is carefully applied and increased thought the takeoff roll so you don't run out of rudder. Once you get the tail up and stopped at the desired pitch attitude, you're in pretty good shape. The airplane is picking up significant speed now, so the rudder is becoming very effective. The P-factor is also reduced with your now lower angle of attack. You still have to pay full attention straight ahead and use the rudders to keep the airplane going straight, especially in a crosswind. Soon, the airplane lifts itself gracefully off the ground. Many people get the tail too high on the takeoff roll and then pull back on the yoke to lift off. It's better to learn the right attitude for your airplane so it flies itself off under normal conditions. This allows you to look straight down the runway and ignore the airspeed indicator so you can keep the airplane straight.

Landing

The final difference you will notice comes during landing. This is probably where the difference seems most significant. First, there are the stability issues discussed above that begin during taxi. These issues have not gone away! When the airplane touches down, it must be going perfectly straight down the runway and its longitudinal axis perfectly aligned with the runway. In other words, no drift or crab (which really are the same thing). Second, at the moment of touchdown, since the center of gravity is behind the main landing gear, it's downward inertia pulls the tail down, thus increasing the angle of attack so the airplane becomes airborne again, or seems to bounce. There are two ways to deal with this. The first is to make sure the tailwheel touches at the same time, or a few inches before the main wheels. This is loosely called a full-stall or three-point landing (there is actually a difference between the full-stall and three-point landing which is discussed in more detail on the landing page). The second is to make a wheel landing, which is where you make your touchdown on the main wheels as smoothly as possible so the center of gravity has little downward inertia. You also anticipate the moment the main wheels touch and push forward a little on the yoke/stick to �stick� it on. You can really push the nose over and actually obtain a zero or slightly negative angle of attack with the wings so you're really �stuck� down to the ground. Both these landing techniques are discussed in much more detail on the landing page.

The merits of wheel landings verses full-stall/three-point landings in a crosswind are discussed in our great debate. Please visit that page and add your comments.

for more informaiton: http://www.taildraggers.com/Documentation.aspx

TYPES OF AIRPLANE LANDING GEARS

A Single Wheel

Some aircraft have only a single tire. Gliders are the most common example of single wheel planes. The pilot must balance a glider on the single wheel during takeoff and landing.

Two wheels

Airplanes called "tail draggers" have two main landing gear and a little wheel or skid on very rear portion of the plane. Tail draggers are steered on the ground with the rudder and require some very specific flying skills when taking off and landing. The infamous "ground loop" happens to the inattentive tail dragger pilot.

Three wheels

The modern landing gear style is the tricycle with two main landing gear and a nose gear. The steerable nose gear makes the tricycle geared airplane easier to steer on the ground. Takeoff and landing with the tricycle style gear is easier to learn than with the tail-dragger. A ground loop is not possible with this style of gear.

Retraction

An airplane's landing gear is either fixed or retractable. Retractable landing gear increases performance and fuel economy by reducing airflow drag. It also ads cost and complexity. A pilot who is switching from fixed gear to retractable needs to make certain to remember to lower the gear before landing.

AIRPLANE VEERED OF THE RUNWAY AT ATATURK AIRPORT

The plane which is belonged to Azerbaijan Airlines and making expedition between Baku-Istanbul, veered of the runway at Ataturk Airport when it was landing.The plane type is A319 and its fuselage,motors and landing gears were broken after accident. According to latest information,after landing, pilot could not stop the airplane at the time of going from pist to apron whereupon the plane was veered of the runway and slide on the soil floor.

Approximately 10 meters getting on the soilfloor airplane was deplaned and carried to the terminal. State Airports Administration started a operation due to moving the airplane from whereabouts.

There are nobody with wounded or died after incident.

The runway was operated after the incident area was cleared.

Harare Airport Plane Accident

An aircraft has been involved in an accident at Zimbabwe's Harare International Airport, a Zimbabwe aviation official say.

The head of Zimbabwe's Civil Aviation Authority, David Chawota, told Reuters news agency there had been "injuries, no deaths".

However, there are conflicting reports saying that the incident was part of a safety drill.

Witnesses said several ambulances were seen heading towards the airport.

AFP news agency is reporting the plane involved was a Boeing 767 flying from London.

The BBC's Brian Hungwe said as he arrived at the airport he could see smoke from its eastern perimeter.

But he said the situation was not clear.

"We are trying to establish what has caused the accident," Mr Chawota told AFP.

For more information: http://www.bbc.co.uk/news/world-africa-10879353

RADAR ALTIMETER

We are going to elaborate on principles of radar altimeters.Let's start.

Radar altimeter is a device which compute the altitude of airplane by using the radio wave.It mesausures the time differences between sending radio wave to the earth and echoing back to the airplane whereupon it takes the time and indicates the altitude of aircraft by using the sound velocity.

Transmitters and receivers are located on fuselage or under the wing.There are two types of altimeter,one of them is High Radio Altimeter and the other is Low Altitude Radio Altimeter.High Radio Altimeters are used for cruise.Going and coming signal times are measured,altitude is found by using h=c*t/2 formula eventually.Error margin is -+50ft.As we said the other types of altimeter are Low Altitude Radio Altimeters that are used generally for instrument landings.Coming and going signal times are compared and measured by shock.Operation frequency is between 4200-4400.Capability of transmitter is 0.5 W and its range is 2500ft.Error margin is -+2ft between 0-500ft altitude and +-%5 of its altitude between 500-2500ft.As you see,Low Radio Altimeters are more sensitive than High Altitude Altimeters.

Plane Crashes in Alaskan National Park

A large cargo-type plane crashed in Alaska Sunday and burst into a deadly fireball that sparked a forest fire at Denali National Park, officials said.

Park spokeswoman Kris Fister said there were fatalities, but it's unclear how many because "the plane pretty much disintegrated."

The fire was challenging responders, who did not immediately know who owns the multiengine aircraft. The plane went down near the park's eastern edge at 3:15 p.m., about 100 yards off the only major road in the park.

No missing planes were immediately reported and military officials have said none of their planes were involved.

Clint Johnson with the National Transportation Safety Board said there are a number of large transport planes operating in Alaska. The NTSB was expected to arrive on scene Monday morning.

'Big ball of flame'
Anchorage resident Jeff Kowalczyk, who witnessed the crash, said the crash site was "a big ball of flame," NBC affiliate KTUU-TV reported.

"We looked back and it started banking to the pilot's left, kept banking more and more until it was upside-down and crashed in the hill right in back of us," Kowalczyk said

"We walked around the perimeter, took about a half-hour for the park rangers to show up and help out — but we saw one body, one body burned pretty bad, pilot probably," he added.

George Clare, of Las Vegas, said he saw the plane flying very low and slowly while he was walking toward the visitor's center near the park entrance. He thought the plane was going to land on a local airstrip, so he proceeded to the visitor's center. Within minutes, people came running in and saying a plane had crashed.

He said the crash caused a column of smoke a few miles west of the visitor's center.

Clare said the aircraft looked like a military plane to him.

"It was a military khaki green kind of color," he said. "It was propeller-driven. It was a fixed wing aircraft and it had kind of a flat underbelly."

Doug Stockdale with the Alaska Fire Service said the fire was initially estimated at two acres but could have grown larger. Smokejumper fire crews were flown to the scene, he said.

The crash happened just four days after a military cargo plane crashed at Elmendorf Air Force Base in Anchorage, killing four people onboard.

The four airmen were on a training mission Wednesday evening for a weekend air show at the Air Force base, which wrapped up Sunday. The C-17 crashed about a minute after taking off.

For more information: http://www.msnbc.msn.com/id/38517169/ns/us_news/