Astronz

Boeing 787 Dreamliner: Composite Airframe May Be Unsafe?

2013-01-15T08:55:00.003-08:00

A former employee Vince Weldon of Boeing claims that the new carbon-composite airframe of the Boeing 787 Dreamliner may be unsafe. who had worked for Boeing for 46 years claims in an interview with journalist Dan Rather that he was fired in 2006 because he pointed out safety glitches in relation to this new breakthrough technology to be used widely in the construction of the Dreamliner (composite is to replace aluminium in the body frame of the airliner

Advantages of Design:

Guarantee weight reduction (thus increased fuel efficiency and less environmental harm)

Possibility of more humidity in the passenger cabin, which would reduce the effects of flying on the human body. At the time when he was laid off.

Risks of its design:

The brittle carbon-composite compounds based airframe would break much easier than the traditional, more flexible aluminium aircraft body in an emergency landing for example (more likely to shatter on any impact actually.

If ignited and catching fire, it would omit poisonous and toxic gases and chemicals while burning,

The fuselage is less resistant to lightnings while flying,

Any damages are harder to see and visually locate.

Advantage of conventional Alluminium aircraft:

Risks would reduce the chance of survival in case of an accident involving any of the above described situations.

In 2007 a McDonnel Douglas airplane has broken in two and caught fire during an (emergency) landing in Thailand, claiming 88 deaths and leaving 42 survivors who could escape the burning airplane – so such a situation can happen with a traditionally built aluminium aircraft as well unfortunately, but the risk of such a situation largely increases by the usage of composite materials.

Who is this Vincent A. Weldon ?

Vincent A. Weldon is an American aerospace engineer, having designed critical components for the Apollo moon mission, as well as the Space Shuttle.

Weldon joined Boeing in 1960, in what was a 46-year career with the firm. He was first involved in the wing design of the Boeing 727 airliner, a design that incorporated high-lift devices such as triple-slotted flaps, which enabled the 727 to be one of the first jet aircraft capable of operating from relatively short runways.

Vince Weldon's experience in the use of composite materials led to him being asked by Boeing to research how advanced composites could be used to build its next generation passenger airliner, the 787 Dreamliner Weldon told Boeing management that the carbon fiber-reinforced plastic material which was being used to construct the Boeing 787 Dreamliner was unsafe, and less safe than a conventional aluminium aircraft. Boeing fired Weldon in July 2006.

Weldon detailed his concerns about the 787 airliner in a letter he wrote to the Federal Aviation Administration (FAA). He also criticised the FAA's guidelines for composite airliners, saying they do not go far enough to guarantee passenger safety on the 787.


Maximum portion of the structure is composite

New Fasteners which works as Crack Sensor

2013-01-06T02:10:00.001-08:00

Alcoa is developing aircraft fasteners with Sanford researchers that also function as sensors capable of detecting crack propagation in multilayer composite structures

The technology could reduce inspection frequencies for wing stringers by one-half. Fatigue cracks forming at fastener holes are a common form of airframe damage.

How it works?

In the invention, a fastener couples layers of a multi-layer structure together via an opening that traverses the structure. A sensor circuit is inserted into the opening with the fastener, inducing an electrical response in a portion of the multi-layer structure adjacent to the opening. If the structure surrounding the fastener hole is damaged, the electrical response is slowed, indicating a failure.

In one example of the technology, a sensor film is embedded on the shank of an aircraft fastener, such as a 1.5 inch shank fastener from Alcoa Fastening Systems. An eddy current is applied to the sensor. The sensor's circuit is established by a coating applied to the fastener and the conformable film.

The sensor circuit includes an active conductor to induce the electrical response, and a passive conductor to sense the induced electrical response. The active and passive conductors are wound around an outer diameter of the mechanical coupler to form an alternating winding pattern of active and passive conductor lines.

"When you plug this in, you can see if there is a crack and if it has propagated," says Bill Christopher, executive vice president of Alcoa.

Structural health monitoring (SHM) technology:

Stanford University developed the structural health monitoring (SHM) technology under a research grant sponsored by Alcoa.

Alcoa's SHM system can be used for aluminum aircraft structures as well as hybrid structures that combine carbon fiber-reinforced composite and aluminum. For example, the SHM system can be applied to the joint between aluminum ribs and carbon fiber reinforced wing skins.

Pre-production prototypes of Alcoa's SHM system are currently being tested with select customers for commercial applications. Alcoa plans to complete comprehensive testing with select customers before SHM reaches full production.

VORTEX SURFING SAVES FUEL AND MONEY

2012-10-18T07:21:00.000-07:00

Flight tests with C-17s "vortex surfing" at Edwards Air Force Base, Calif., Sept. 6 and Oct. 2, have demonstrated potentially large savings of fuel and money by doing what geese do naturally. Tests show that flying in formation might be smarter than flying alone for Airmen, and not just for birds

Vortex surfing involves the whirlwinds of turbulence generated at the wingtips of planes in flight. Because they produce turbulence and drag, aeronautical engineers do their best to minimize these. That’s the reason for the little winglets on aircraft. Now, instead of trying to get rid of vortices, the USAF is trying to exploit them to increase fuel economy.

This may be cutting edge as far as aviation is concerned, but vortex surfing has been around a long time. In fact, nature has been exploiting it for millions of years. Geese flying in formation vortex surf. The lead bird generates vortices as it flies and the other geese position themselves inside the wave of turbulence also known as a slipstream. Though the lead bird is working hard, the vortices it generates increase lift for the following birds. The lead bird has to work harder, but the net energy savings for the flock as a whole goes down.

The concept, formally known as Surfing Aircraft Vortices for Energy, or SAVE, involves two or more aircraft flying together for a reduced drag effect like what you see with a flock of geese," said Dr. Donald Erbschloe, the Air Mobility Command chief scientist.

Early indications from the tests promise a reduction of fuel consumption by up to 10 percent for the duration of a flight. Over long distances and with even a small fraction of Air Mobility Command's average of more than 80,000 flights a year, the fuel and cost savings could reach into the millions of dollars, experts say.

The Air Force Research Laboratory will analyze the data from for possible applications to other aircraft on a variety of missions.

Dr. Erbschloe said larger air mobility aircraft like the C-17 can fly in formations that are potentially easy to maintain and which do not require the planes to be exceptionally close together.

"The test flights were flown at longitudinal separations of 4,000 or greater," said William Blake, one of the key developers of save at the AFRL.

According to AFRL officials, modified C-17 formation flight system software enabled precise auto-pilot and auto-throttle systems to ensure the trailing aircraft achieved and maintained proper flight position without active assistance from pilots.

"The autopilot held the position extremely well -- even close to the vortex," said Capt. Zachary Schaffer, an aircraft commander on one of the test flights. "The flight conditions were very safe; this was as hands-off as any current formation flying we do."

Other pilots found differing levels of ride quality and discovered some flight test points might be difficult for long-endurance flights.

"The key will be finding the right balance of quality for improving fuel efficiency and ride," said Maj. Eric Bippert, another aircraft commander on one of the test flights.

Bippert said being a part of the test program with so many talented engineers was a remarkable experience, and the concept could eventually impact global air transportation, overall.

"AMC has done really well with fuel efficiency at the operational level," said Erbschloe. "The command has worked to gain efficiencies from the 'low-hanging fruit' such as optimizing flight routing, reducing weight where possible, and by not carrying excess fuel. save offers significant efficiency gains, if employed in concert with these initiatives."

He said early indications show the tests meet AMC criteria of the concept regarding safety and minimization of aircrew and aircraft strain while also being operationally sensible with a viable return on investment.

"AMC consumes 20 percent of the fuel used by the overall federal government, so we're constantly looking for pragmatic ways to improve our fuel efficiency," said Erbschloe.

"Assured energy advantage for our Air Force is only possible through revolutionary energy initiatives like save," said Dr. Mark Maybury, Air Force chief scientist, upon hearing the results of the tests.

The save concept was previously highlighted in the 2011 Energy Horizons study, sponsored by the Secretary of the Air Force and chaired by Maybury.

The tests were the culmination of an ongoing, combined effort between AMC, the AFRL, the 412th Test Wing, the Air Force Life Cycle Management Center, the Defense Advanced Research Projects Agency, the Boeing Company and NASA Dryden Flight Research Center.

Morphing leading edge reduces drag and noise in takeoff and landing

2012-09-10T07:08:00.002-07:00

The morphing leading edge concept would replace traditional leading edge slats on fixed wing aircraft

Passengers looking out the window of a passenger plane will likely have noticed slats on the leading edge of the wing, along with the flaps on the trailing edge of the wing, being extended during takeoff and landing. These leading edge slats provide the lift necessary at low speeds, with the gap between the wing and the slats directing air from the underside of the wing to the top. Unfortunately, this gap also generates a lot of noise. A team of researchers has now developed a morphing leading edge that eliminates the gap and reduces noise and drag during landing.

The “smart droop nose” developed by researchers at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) working with partners Airbus, EADS Innovation Works and Cassidian Air Systems, literally morphs into a different shape during takeoff and landing so that no separate slats – and no gap – is necessary.

The morphing leading edge can be lowered by up to 20 degrees with virtually no loss of lift

In developing the new leading edge, the researchers faced a number of challenges. "On the one hand, the structure needs to be very elastic, to enable it to morph to the required shapes, but on the other it has to be very rigid,” said DLR Department Head Hans-Peter Monner. Ultimately, the leading edge must bear around one third of the weight of the aircraft during landing."

The morphing leading edge is made from glass-fiber reinforced material

The material also had to produce wing surfaces that are as flat as possible to achieve laminar airflow. Concentrating on the glass- and carbon-fiber reinforced composites typically used by the aviation industry, they found that glass-fiber reinforced material best fit the bill.

The droop nose design concept also sees the skin on the front edge of the wing curved, rather than stretched to minimize the stress placed on the material. Individual layers are then placed on top of each other so that the skin creates a structure with a customized rigidity distribution. The leading edge them morphs into the desired shape using actuators and support elements integrated along the wingspan.
The researchers have tested the system’s operation and performance in in one of Europe's largest wind tunnels at the Russian Central Aerohydrodynamics Institute’s (TsAGI) Zhukovsky research facility south of Moscow and found that the morphing leading edge can be lowered by up to 20 degrees with virtually no loss of lift.
The team plans to continue development of the concept to meet industrial requirements, such as lightning protection, de-icing and the ability to withstand bird strikes.

The morphing leading edge being tested at a wind tunnel in Moscow

This article is taken from AERO GIZMO.

Presentation on Aircraft propulsion system

2012-07-26T08:14:00.000-07:00

This is my presentation on propulsion system of aircraft.
You can get basic idea of jet propulsion of aircraft in this presentation

To view the presentation click below

http://www.authorstream.com/Presentation/avionraky-1483268-aircraft-jet-propulsionsystem/

G-Suit

2012-06-04T09:35:00.002-07:00

G.Force, you might familiar with this term. when you are in the giant wheel, little G-force can be experienced. But this is very small amount, we can not even sustain this small amount of G-force, then think about the Astronauts and fighter Pilots. they has to sustain the G-force of amount 3G to 10G.

Earth gravity is 9.8 m/s2.
3G = 3 * 9.8 m/s2
now imagine 10G = 10* 9.8 m/s2
At this higher G-force our blood pressure goes to higher, and sometimes it leads to death.

There are two types of people experienced this G-force on a regular basis. Astronauts and fighter plane pilots.
Astronauts experiences when they are taking-off and re-entry situation. particularly when they re-entry.
when Astronauts re-entry to the earth atmosphere their space shuttle velocity is about 28,000 km/hr, this is hypersonic speed. at this situation they experience 10G.and their blood pressure is higher. To withstand this force they ware G-Suits.

How G-suit work : The suit is only pair of Chaps that has a waist that wraps around your gut. It has a hose that plugs into the aircraft which forces compressed air into bladders built into the suit. When the aircraft makes tight turns, causing g loads on the pilot, it forces the air into the lower legs, thighs, and gut area to force blood back up into the torso and to prevent it from pooling into your legs.

If they lose too much blood from their head under these loads they will lose consciousness and pass out. Once they pass out they will lose control and risk crashing. The G suit does not do all the work however, it only helps. The Astronaut in the spacecraft still has to do an enourmous amount of work to retain consciousness. They must flex the muscles in their legs and abs as hard as he can and take short, forced breaths.

After the re-entry Astronauts were loose their consciousness and feel giddy. It will take a week for them to come to normal situation.

SPACE ELEVATOR

2012-03-17T10:55:00.000-07:00

Hello friends you might heard the story in MAHABARATHA, in which Arjuna was built a ladder to heaven through which Bheema was traveled.Yes its a story written by great "Vyasa maharshi". The same thing is going to be real now, you can travel to space and that too takes 5 hours journey, you can observe our Earth curvature and the sky turns to black color from blue. Which sounds like a Sci-fi movie story.

But this is not a story, this is real and this is really possible in our world, which is called SPACE ELEVATOR.

"Elevator to space". A space transportation system.Yuri Artsutanov first proposed the idea in 1960, and up until 15 years ago it was purely in the realm of science fiction. But Sumio Iijima's discovery of CARBON NANOTUBES (CNTs) in 1990 and Bradley Edward's engineering research in 2001 is clearing the road map to a space elevator's construction. Scientists today are conducting a lot of research in the field of nanotube tethers for commercial applications on Earth. Sooner than most people expect, I hope a space-elevator-capable CNT tether will become available and kick the space elevator's development into high gear.

A space elevator is essentially a long cable extending from our planet's surface into space with its center of mass at geostationary Earth orbit (GEO), 35,786 km in altitude. Electromagnetic vehicles traveling along the cable could serve as a mass transportation system for moving people, payloads, and power between Earth and space. Current plans call for a base tower approximately 50 km tall -- the cable would be tethered to the top. To keep the cable structure from tumbling to Earth, it would be attached to a large counterbalance mass beyond geostationary orbit, perhaps an asteroid moved into place for that purpose.

Carbon nanotube :

CNT is a new form of carbon, equivalent to a flat graphene sheet rolled into a tube. CNT exhibits extraordinary
mechanical properties: the Young's modulus is over 1 TeraPascal and the estimated tensile strength is 200 GigaPascals. Fiber materials such as graphite, alumina, and quartz have exhibited tensile strengths greater than 20 GPa during laboratory testing for cable tethers. The desired strength for the space elevator is about 62 GPa. Carbon nanotubes have exceeded all other materials and appear to have a theoretical strength far above the desired range for space elevator structures. "The development of carbon nanotubes shows real promise," said Smitherman. "They're lightweight materials that are 100 times stronger than steel."

And there are some more technologies to build such a elevator.but CNT is the present assumption.

In his last years, Sir Arthur C. Clarke predicted that the space elevator will be built "about 10 years after everyone stops laughing". I believe people will stop laughing once a proper tether is demonstrated, and we think that this will happen within 5 to 10 years. Hopefully that means about 15 to 20 years before the first launch.

Conceptual pictures:

Videos:

NOVA Science now video

Hummel Helicopter

2012-03-07T07:28:00.000-08:00

Exited....? Even i was exited.

This is the new concept of light weighted helicopter with TANDEM DUCTED ROTOR design.

The passenger capacity is two and it will not take more space, it can be folded flat.

The Hummel could be of great help in emergency situations, when there is minimal space, because of its small size and folding ability.

Hemmel means "Bumble bee"

But this is just a conceptual design.It won't take much time for prototype.

It can be used for passenger transport, emergency transports like organs or units of stored blood and for conventional tasks, such as monitoring (e.g. coast guard, police, army, scientists).

This dose not require Helipad.

Further detail click the link below:

TILTROTOR

2012-02-21T09:51:00.000-08:00

" TILTROTOR" this is the new terminology we hearing now a days. All the aviation people use to think about such a design which uses VTOL and Fixed wing aircraft. We think this design is not implemented yet, but this is.
Yes what you heard is right. it is implemented and waiting for FAA certification.

AGUSTAWESTLAND is one of the aviation firms made this dream come true. The shown pictures are the AW609 aircraft.

The unique characteristics of the AW609 Tiltrotor combine the benefits of a helicopter and a fixed wing aircraft into one aircraft. Taking off and landing vertically, flying above adverse weather conditions with up to nine people in comfort in a pressurised cabin at twice the speed and range typical of helicopters, the AW609 represents the next generation of aircraft transport for civil (both private and commercial operators), government and para-public roles. This multi-role aircraft can be configured for passenger transport, search and rescue, law enforcement, maritime surveillance, training and government applications. The AW609 will be certified for instrument flying in known icing conditions and features a composite fuselage and wings, an advanced glass cockpit and full fly-by-wire digital controls. These advanced technologies will provide new levels of performance, reliability and affordability for future operators.

Its Applications:

» COAST GUARD

The performance characteristics of the AW609 offer coast guards capabilities and cost-effectiveness simply not available in any other single aircraft. The AW609 offers coast guard operators highly cost-effective and time efficient point-to-point transportation at speeds up to 275 knots and ranges up to 700 nm.

» EMS/SAR

The AW609 is a multi-mission tiltrotor aircraft designed to employ the speed of a turboprop airplane with the vertical takeoff and landing capability of a helicopter offering unique capabilities to EMS/SAR operators. For EMS and SAR operations, the AW609 offers basket, litter and a 600 lb capacity exterior hoist option.

» OFFSHORE

The AW609 offers speed, range, all weather capability and comfort making it an ideal aircraft to transport crew offshore. Designed from the outset for low maintenance and maximum operational flexibility, the AW609 will offer operators cost-effective, point-to-point transportation at cruise speeds up to 275 knots and at ranges up to 700 nautical miles. This long range capability makes the AW609 particularly suited to “deepwater” operations in the Oil & Gas industry.

» GOVERNMENT VVIP

The AW609 offers new flexibility in transport for VVIPs and Heads of State. The combination of vertical takeoff and landing together with range capability and speed enable the VVIP to reach distant congested urban areas directly, quickly and with high levels of security. The pressurised spacious cabin provides a comfortable and productive working environment and the aircraft has ample space to carry any necessary luggage.

AW609 Demonstration

TECHNICAL DATA:

Weights
Max take off	7620	kg	16800	lb
Max useful load	2495	kg	5500	lb

Engine Rating (2 x Pratt & Whitney PT6C-67A)
Take off power	1447	kW	1940	shp
Maximum continuous power	1249	kW	1675	shp

Fuel Capacity
Standard*	2470	lb	369	USgal

* Unusable Fuel 50 l (13 USgal)

Crew
Pilots / Passengers	2 / 9

External Dimensions
Length (overall)	14.04	m	46	ft
Overall height	5.10	m	16.70	ft
Prop rotor diameter	7.92	m	26	ft

Performance (ISA - MTOW - pending certification)
Max demonstrated speed	616	km/h	333	kts
Max cruise speed	509	km/h	275	kts
Rate of climb	n.a.	m/s	n.a.	ft/min
Operational ceiling	7620	m	25000	ft
Max range (standard tanks)	1296	km	700	nm
Cabin pressure altitude	8000	ft	2438	m

EQUPMENT

Pressurised cabin
Fly by wire flight control system
Heated composite rotor blades
Nine seat interior with soundproofing

AVIONICS SYSTEMS

3 multi-function active matrix Liquid Crystal Displays (LCDs)
Full IFR package
Dual-channel Nacelle Interface Unit (NIU) (each nacelle)
Dual-channel data concentrator unit
System maintenance diagnostics computer
Integrated Avionics Processor Unit (IAPS)
Flight guidance system
Flight management system
Global positioning system
Weather radar
ELT

Satellite orbit information

2012-02-11T07:40:00.000-08:00

Geostationary Orbit

The most common orbit used for satellite communications is the geostationary orbit (GEO). This is the orbit described above – the rotational period is equal to that of the Earth. The orbit has zero inclination so is an equatorial orbit (located directly above the equator). The satellite and the Earth move together so a GEO satellite
appears as a fixed point in the sky from the Earth.

The advantages of such an orbit are that no tracking is required from the ground station since the satellite appears at a fixed position in the sky. The satellite can also provide continuous operation in the area of visibility of the satellite. Many communications satellites travel in geostationary orbits, including those that relay TV signals into our homes.

However, due to their distance from Earth GEO satellites have a signal delay of around 0.24 seconds for the complete send and receive path. This can be a problem with telephony or data transmission. Also, since they are in an equatorial orbit, the angle of elevation decreases as the latitude or longitude difference increases between the satellite and earth station. Low elevation angles can be a particular problem to mobile communications.

Low Earth Orbit/Medium Earth Orbit

A low earth orbit (LEO), or medium earth orbit (MEO) describes a satellite which circles close to the Earth. Generally, LEOs have altitudes of around 300 – 1000 km with low inclination angles, and MEOs have altitudes of around 10,000 km.

A special type of LEO is the Polar Orbit. This is a LEO with a high inclination angle (close to 90degrees). This means the satellite travels over the poles.


Satellites that observe our planet such as remote sensing and weather satellites often travel in a highly inclined LEO so they can capture detailed images of the Earth’s surface due to their closeness to Earth. A satellite in a Polar orbit will pass over every region of Earth so can provide global coverage. Also a satellite in such an orbit will sometimes appear overhead (unlike a GEO which is only overhead to ground stations on the equator ). This can enable communication in urban areas where obstacles such as tall buildings can block the path to a satellite. Lastly, the transmission delay is very small. Any LEO or MEO system however , for continuous operation, requires a constellation of satellites. The satellites also move relative to the Earth so wide beam or tracking narrow beam antennas are needed.

Elliptical Orbit

A satellite in elliptical orbit follows an oval - shaped path. One part of the orbit is closest to the center of Earth (perigee) and another part is farthest away ( apogee ). A satellite in this type of orbit generally has an inclination angle of 64 degrees and takes about 12 hours to circle the planet. This type of orbit covers regions of high latitude for a large fraction of its orbital period.

How the star born?

2012-01-28T20:38:00.000-08:00

Click the below

Video of how the star born?

New Fixed Wing Digital Audio Panel Optimized For Fixed-Wing Aircraft

2012-01-26T07:05:00.000-08:00

A new fixed wing digital audio panel for the Digital Audio and Intercom System DVCS6100 was unveiled at NBAA 2011 by Becker Avionics.

The new panel variant of the Audio Control Unit (ACU) 6100 is specifically tailored for fixed-wing applications. The new fixed-wing ACU6100 comes in a horizontal and vertical format to ease retrofit installations.

The new fixed-wing audio control panel is similar to the standard ACU6100, but includes oxygen mic switching, marker beacon mute and other functions. The panel will be available in a number of different lighting options, from soft white light to NVG compatible lighting. The ACU6100 is a pushbutton audio selector panel that controls all audio and intercom functionality for the systems Remote Electronic Unit (REU) 6100 via a dual CAN-Bus connection.

The DVCS6100 integrates all communications in the aircraft and provides flexible user-programmable configurations. The system offers a unique ability to effectively manage and control multiple audio sources and cabin passenger positions. Becker’s Digital multichannel audio and intercom system provides the flexibility to specifically customize the system to meet the demanding requirements of business aviation and airlines.

The DVCS6100 manages all transceivers, receivers and audio warning sources in one central system. It provides inter phone communication for up to 6 audio control stations to meet crew member needs. The system can handle up to 8 transceivers, 8 receivers, 6 fixed inputs and 8 warning tones. The DVCS6100 is the newest generation audio management system and was designed to meet specific needs of commercial and business aviation applications. Adaptable to all airborne applications, from large to small platforms, the DVCS6100 provides crisp and clear audio communication.

The Becker Avionics' DVCS 6100 also provides an optional Cabin Intercommunication and Passenger Address system, consisting of the Control Panel CP3100, External Jack Box EB3100, Intercom Amplifier IC3100, Public Address Amplifier PA3100, Converter Box CB 3100, Service Station ST3100, and Digital Player DP 4100. The DVCS6100 easily integrates all communications in the aircraft and provides flexible user-programmable configurations.

Link: http://www.aero-tv.net/index.cfm?videoid=ac6fafe1-913f-4ece-8e8a-a10288d34467

Books for aeronautical students

2012-01-26T04:06:00.000-08:00

Aerodynamics and Flight Mechanics E-Books

http://www.4shared.com/dir/3691758/3...odynamics.html

Aerodynamics for Engineering Students by E.L.Houghton (2002) [9.21MB]

http://rapidshare.de/files/21089629/...__5th_ed._.rar

Applied Aerodynamics Education by Devenport Mason [0.19MB]

http://rapidshare.de/files/22492513/...aa-98-2791.pdf

Missile Aerodynamics by J.N.Nielson (1960) [19.87MB]

http://rapidshare.de/files/22493320/...Hill_1960_.pdf

Aerodynamics, Aeronautics and Flight Mechanics by McCormick [3.43MB]

http://rapidshare.de/files/22492628/...an_p1-179_.pdf

A scientist at Cambridge University has debunked the long-held myth about how aircraft stay aloft

2012-01-25T22:47:00.000-08:00

Aeroplanes can fly as their wings cause the air pressure underneath to be greater than that above, lifting them into the air. But, engineers have for years been frustrated by a theory which wrongly explains what causes the pressure change, a myth commonly found in school textbooks and flight manuals.

But, Holger Babinsky of Cambridge University's engineering department has now created a minute-long video, posted on You-Tube website, to lay to rest the myth once and for all, the Daily Telegraph reported.

According to conventional wisdom, the pressure change happens as the air on the curved upper surface of the wing has further to travel than that below the flat underneath surface, meaning it must travel faster to arrive at the other side of the wing at the same time.

Babinsky says the myth goes against the laws of physics and the real explanation has nothing to do with the distance the air has to travel. According to him, the curvature of the wing causes the change in air pressure because it pulls some of the air upwards, which reduces pressure, and forces the rest beneath it, creating higher pressure.

A law known as the Bernoulli equation means that when pressure is lower, air moves faster - so the air stream above the wing does moves more quickly than the one below, but this is not what causes the difference in pressure.

Babinsky proved his theory by filming smoke passing across a wing. If traditional wisdom had been correct the smoke above and below the wing should have reached the front edge at the same time. The video demonstrates that the explanation is fundamentally flawed because the plume above the wing reached the edge much sooner than the plume below, he says.

Fly NASA (Where the sky is not the limit)

2012-01-25T10:19:00.000-08:00

Want a career that’ll take you full circle? Adventure. Commitment. Leadership. Achievement. These are the core values of NASA’s distinguished astronaut corps. They’re also the rewards of fulfilling work. The 21st century astronaut will serve on long-duration missions aboard the International Space Station – and future deep space missions. NASA is going places where there are no boundaries. Your unique talents and experiences can take you there too.

Because NASA understands it is what makes us different that makes us successful as a nation, it seeks fresh perspectives to take us out of this world.

All U.S. civilians and active duty military personnel with a bachelor’s degree in engineering, science or math and three years of professional experience meet the requirements to apply to become the next highest class of astronaut candidates on Earth.

Apply to explore with us. Fly NASA, where the sky is not the limit.