Pitot-Static Flight Instruments

Laversab Aviation Systems is a leading supplier of Air Data Test Sets and Pitot Static Testers to the Aviation Industry.

There are two major parts of the pitot-static system: the impact pressure chamber and lines, and the static pressure chamber and lines. They provide the source of ambient air pressure for the operation of the altimeter, vertical speed indicator (vertical velocity indicator), and the airspeed indicator.

IMPACT PRESSURE CHAMBER AND LINES

In this system, the impact air pressure (air striking the airplane because of its forward motion) is taken from a pitot tube, which is mounted in locations that provide minimum disturbance or turbulence caused by the motion of the airplane through the air. The static pressure (pressure of the still air) is usually taken from the static line attached to a vent or vents mounted flush with the side of the fuselage. This compensates for any possible variation in static pressure due to erratic changes in airplane attitude.

The openings of both the pitot tube and the static vent must be checked during the preflight inspection to assure that they are free from obstructions. A certificate mechanic should clean blocked or partially blocked openings. Blowing into these openings is not recommended because this could damage the instruments.

As the airplane moves through the air, the impact pressure on the open pitot tube affects the pressure in the pitot chamber. Any change of pressure in the pitot chamber is transmitted through a line connected to the airspeed indicator, which utilizes impact pressure for its operation.

STATIC PRESSURE CHAMBER AND LINES

The static chamber is vented through small holes to the free undisturbed air, and as the atmospheric pressure increases or decreases, the pressure in the static chamber changes accordingly. Again, this pressure change is transmitted through lines to the instruments, which utilize static pressure.

An alternate source for static pressure is provided in some airplanes in the event that the static ports become blocked. This source usually is vented to the pressure inside the cockpit. Because of the venturi effect of the flow of air over the cockpit, this alternate static pressure is usually lower than the pressure provided by the normal static air source. When the alternate static source is used, the following differences in the instrument indications usually occur: the altimeter will indicate higher than the actual altitude, the airspeed will indicate greater than the actual airspeed, and the vertical speed will indicate a climb while in level flight.

How Airplanes Work (Part 5)

The tail of the airplane has two types of small wings, called the horizontal and vertical stabilizers. A pilot uses these surfaces to control the direction of the plane. Both types of stabilizer are symmetrical airfoils, and both have large flaps to alter airflow.

On the horizontal tail wing, these flaps are called elevators as they enable the plane to go up and down through the air. The flaps change the horizontal stabilizer's angle of attack, and the resulting lift either raises the rear of the aircraft (pointing the nose down) or lowers it (pointing the nose skyward).

Meanwhile, the vertical tail wing features a flap known as a rudder. Just like its nautical counterpart on a boat, this key part enables the plane to turn left or right and works along the same principle.

Finally, we come to the ailerons, horizontal flaps located near the end of an airplane's wings. These flaps allow one wing to generate more lift than the other, resulting in a rolling motion that allows the plane to bank left or right. Ailerons usually work in opposition. As the right aileron deflects upward, the left deflects downward, and vice versa. Some larger aircraft, such as airliners, also achieve this maneuver via deployable plates called spoilers that raise up from the top center of the wing.

By manipulating these varied wing flaps, a pilot maneuvers the aircraft through the sky. They represent the basics behind everything from a new pilot's first flight to high-speed dogfights and supersonic, hemisphere-spanning jaunts.

This Laversab Aviation article will be continued. Airplanes are incredibly sophisticated machines. For one to function properly, it relies on hundreds of sophisticated component parts; some of them include: pitot static test equipment, air data test sets, RVSM test equipment.

How Airplanes Work (Part 4)

Aerial Navigation: Wings, Slats and Flaps

Having covered the basic physics of flight and the ways in which an airplane uses them to fly, the next obvious step is to consider navigation. How does an airplane turn in the air? How does it rise to a higher altitude or dive back toward the ground?

First, consider the angle of attack, the angle that a wing (or airfoil) presents to oncoming air. The greater the angle of attack, the greater the lift. The smaller the angle, the less lift. Interestingly enough, it's actually easier for an airplane to climb than it is to travel at a fixed altitude. A typical wing has to present a negative angle of attack (slanted forward) in order to achieve zero lift. This wing positioning also generates more drag, which requires greater thrust.

In general, the wings on most planes are designed to provide an appropriate amount of lift (along with minimal drag) while the plane is operating in its cruising mode. However, when these airplanes are taking off or landing, their speeds can be reduced to less than 200 miles per hour (322 kilometers per hour). This dramatic change in the wing's working conditions means that a different airfoil shape would probably better serve the aircraft. Airfoil shapes vary depending on the aircraft, but pilots further alter the shape of the airfoil in real time via flaps and slats.

During takeoff and landing, the flaps (on the back of the wing) extend downward from the trailing edge of the wings. This effectively alters the shape of the wing, allowing it to divert more air, and thus create more lift. The alteration also increases drag, which helps a landing airplane slow down (but necessitates more thrust during takeoff).

Slats perform the same function as flaps (that is, they temporarily alter the shape of the wing to increase lift), but they're attached to the front of the wing instead of the rear. Pilots also deploy them on takeoff and landing.

Pilots have to do more than guide a plane through takeoff and landing though. They have to steer it through the skies, and airfoils and their flaps can help with that, too.

This Laversab Aviation article will be continued. Airplanes are incredibly sophisticated machines. For one to function properly, it relies on hundreds of sophisticated component parts; some of them include: pitot static test equipment, air data test sets, RVSM test equipment.

Model 6580 Air Data Tester

Laversab Aviation Systems provides high accuracy RVSM air data testers to the Aviation Industry world-wide. The Model 6580 Air Data Test Set is designed to test the entire pitot and static system of the aircraft, including altimeters, climb indicators, airspeed / Mach indicators, air data computers and auto-pilots. It is configured for a 19" rack and occupies 4U height. Recently assigned an NSN: 4920 01 611 1045, this RVSM Tester is ideal for use either on the bench or in ATE systems.

 The built-in vacuum and pressure pumps on the Model 6580 ADTS make it easy to use.  No external pumps are required. The internal pumps are designed to run very quietly and transfer minimal vibration to the enclosure. GPIB and RS232 interfaces are standard on this Air Data Tester.  The Model 6580 may be ordered with an optional Remote unit. A very high accuracy version (Model 6580-HA) and a low-airspeed version for helicopters and UAV's (Model 6580-HA-LR) are also available.

Model 6300 Pitot Static Tester

Laversab Aviation Systems has been providing reliable and innovative air data testers to the Aviation Industry for more than 30 years. Our legendary model 6300 two-channel Pitot Static tester is primarily used in the Commercial, Business and General Aviation sectors, with a Military version covering a broader range suitable for the Fighter/Attack jets.

The 6300 Automated Pitot Static Tester connects directly to an aircraft’s Pitot and Static system. Using the small and lightweight Remote unit, a user can operate the tester from the cockpit and use it to test the entire pitot and static system of the aircraft, including altimeters, climb indicators, airspeed / Mach indicators, air data computers and auto-pilots. This air data tester includes built-in vacuum and pressure pumps and emergency manual bleed-down valves. The operator simply connects power, and the pitot and static hoses, to make the unit operational.

The high accuracy of this Air Data Test Set meets RVSM requirements. This tester needs to be calibrated only once a year. The use of “Profiles” makes it possible for the operator to run through a test using only a single key on the Remote unit. Additionally, all commands can be performed through the RS232 interface.

With a typical lifespan of 20 years, the 6300 Pitot Static Tester provides an excellent return on investment. With outstanding support provided by Laversab over the life of this RVSM tester, the 6300 delivers unsurpassed value.

How Airplanes Work (Part 3)

Every object on Earth has weight, a product of both gravity and mass. A Boeing 747-8 passenger airliner, for instance, has a maximum takeoff weight of 487.5 tons (442 metric tons), the force with which the weighty plane is drawn toward the Earth.

Weight's opposing force is lift, which holds an airplane in the air. This feat is accomplished through the use of a wing, also known as an airfoil. Like drag, lift can exist only in the presence of a moving fluid. It doesn't matter if the object is stationary and the fluid is moving (as with a kite on a windy day), or if the fluid is still and the object is moving through it (as with a soaring jet on a windless day). What really matters is the relative difference in speeds between the object and the fluid.

As for the actual mechanics of lift, the force occurs when a moving fluid is deflected by a solid object. The wing splits the airflow in two directions: up and over the wing and down along the underside of the wing.

The wing is shaped and tilted so that the air moving over it travels faster than the air moving underneath. When moving air flows over an object and encounters an obstacle (such as a bump or a sudden increase in wing angle), its path narrows and the flow speeds up as all the molecules rush though. Once past the obstacle, the path widens and the flow slows down again. If you've ever pinched a water hose, you've observed this very principle in action. By pinching the hose, you narrow the path of the fluid flow, which speeds up the molecules. Remove the pressure and the water flow returns to its previous state.

As air speeds up, its pressure drops. So the faster-moving air moving over the wing exerts less pressure on it than the slower air moving underneath the wing. The result is an upward push of lift. In the field of fluid dynamics, this is known as Bernoulli's principle.

This Laversab Aviation article will be continued. Airplanes are incredibly sophisticated machines. For one to function properly, it relies on hundreds of sophisticated component parts; some of them include: pitot static test equipment, air data test sets, RVSM test equipment.

How Airplanes Work (Part 2)

How Do Planes Fly: Thrust and Drag

Drop a stone into the ocean and it will sink into the deep. Chuck a stone off the side of a mountain and it will plummet as well. Sure, steel ships can float and even very heavy airplanes can fly, but to achieve flight, you have to exploit the four basic aerodynamic forces: lift, weight, thrust and drag. You can think of them as four arms holding the plane in the air, each pushing from a different direction.

First, examine thrust and drag. Thrust, whether caused by a propeller or a jet engine, is the aerodynamic force that pushes or pulls the airplane forward through space. The opposing aerodynamic force is drag, or the friction that resists the motion of an object moving through a fluid (or immobile in a moving fluid, as occurs when you fly a kite).

If you stick your hand out of a car window while moving, you'll experience a very simple demonstration of drag at work. The amount of drag that your hand creates depends on a few factors, such as the size of your hand, the speed of the car and the density of the air. If you were to slow down, you would notice that the drag on your hand would decrease.

We see another example of drag reduction when we watch downhill skiers in the Olympics. Whenever they get the chance, they'll squeeze down into a tight crouch. By making themselves "smaller," they decrease the drag they create, which allows them to zip faster down the hill.

A passenger jet always retracts its landing gear after takeoff for a similar reason: to reduce drag. Just like the downhill skier, the pilot wants to make the aircraft as small as possible. The amount of drag produced by the landing gear of a jet is so great that, at cruising speeds, the gear would be ripped right off the plane.

For flight to take place, thrust must be equal to or greater than the drag. If, for any reason, the amount of drag becomes larger than the amount of thrust, the plane will slow down. If the thrust is increased so that it's greater than the drag, the plane will speed up.

This Laversab Aviation article will be continued. Airplanes are incredibly sophisticated machines. For one to function properly, it relies on hundreds of sophisticated component parts; some of them include: pitot static test equipment, air data test sets, RVSM test equipment.

How Airplanes Work (Part 1)

Human flight has become a tired fact of modern life. At any given moment, roughly 5,000 airplanes crisscross the skies above the United States alone, amounting to an estimated 64 million commercial and private takeoffs every year [source: NATCA]. Consider the rest of the world's flight activity, and the grand total is incalculable.

It is easy to take the physics of flight for granted, as well as the ways in which we exploit them to achieve flight. We often glimpse a plane in the sky with no greater understanding of the principles involved than a caveman.

How do these heavy machines take to the air? To answer that question, we have to enter the world of fluid mechanics.

Physicists classify both liquids and gases as fluids, based on how they flow. Even though air, water and pancake syrup may seem like very different substances, they all conform to the same set of mathematical relationships. In fact, basic aerodynamic tests are sometimes performed underwater. To put it simply, a salmon essentially flies through the sea, and a pelican swims through the air.

The core of the matter is this: Even a clear sky isn't empty. Our atmosphere is a massive fluid layer, and the right application of physics makes it possible for humans to traverse it.

In this article, we'll walk through the basic principles of aviation and the various forces at work in any given flight.

This Laversab Aviation article will be continued. Airplanes are incredibly sophisticated machines. For one to function properly, it relies on hundreds of sophisticated component parts; some of them include: pitot static test equipment, air data test sets, RVSM test equipment.

Laversab opens a Calibration Center in Chile

Laversab Inc. a leading global provider of RVSM Pitot Static Testers and Air Data Test Set is proud to announce the opening of a new calibration center in Santiago, Chile. Desarrollo de Tecnologías y Sistemas Ltda., (DTS Chile) is the latest overseas Calibration Center demonstrating our ongoing efforts to have local calibration presence for our customers.

DTS has a technical Support Specialists team at their facility, and they will perform the maintenance and calibration of the equipment of Laversab customers in the region, as well as offer direct user help.