Airtimes

If you’re flying in a commercial airliner and the engines cut out will the plane fall out of the sky or will there be time to land safely on the ground? (I’m scared out of my mind every time I fly)

Commercial airliners are good gliders and the "Glimli Glider" is a great example of how it can be put to good use.

At altitude you have substantial amount of potential energy by virtue of its position. This can be converted into kinetic energy, which means forward air speed. The airliner doesnt care if it is powered or not, all it needs is forward air speed. A good pilot can maintain the airspeed and glide to a safe landing.

Technorati Tags: Air Speed, airplane crash, Airplane Engines, Airspeed, Altitude, Commercial Airliner, Commercial Airliners, Fly, Forward Air, glider, Gliders, Kinetic Energy, pilot, Potential Energy, Quot, sky, Virtue

Ok im doing a report on airplanes from the small ones to the airliner jets and was wondering what exactly it means when a plane stalls. Also are there different type of stalls, and do pilots stall on purpose? And finally can you recover from a stall once it happens?

A stall is when the angle of attack, the angle at which the wings meet the onrushing air, is exceeded and the wings lose lift causing the plane to drop. The angle of attack at which this happens can vary depending upon the airspeed. Sufficient flow of air must continue over the wings to maintain lift. A stall can occur very basically speaking when one of two things may happen:
Too steep an angle of attack with insufficient flow of air over the wings causing a stall or
Insufficient airspeed at any angle, again not enough airflow over the wings.
A stall can be easily recovered from providing you have sufficient space between you and anything hard underneath you (like ground).
Pilots are trained to induce stalls thereby learning to recover from them.

Technorati Tags: Airflow, airplanes, Airspeed, Angle Of Attack, Ground Pilots, jets, Sufficient Space, Wings

just curious.

Aircraft approach speed and touchdown speed vary considerable depending on the weight of the aircraft and its configuration. But consider this: How long would it take to stop an aircraft going 220 mph at touchdown? A 747 could easily weigh 350,000 pounds, going at 220 mph, thats a LOT of energy to dissipate and that takes a lot of runway.

That is why most aircraft are fitted with things known as "high-lift devices" These things bend off the front and back of the wing to increase its "Curviness" (if you want to sound smart you can call it camber) These devices are known as flaps. They allows the aircraft to maintain the required amount of lift at a MUCH slower airspeed. A 350,000 pound airplane needs to make 350,000 pounds of lift in order to keep flying. The downside to these devices is that they slow the aircraft down dramatically. this is not such a bad thing when tryong to land ai arcraft.

Basically, the approach speed of an aircraft (known as Vref) vary considerably depending on the weight of the aircraft, but that range typically starts around the 100knot (114mph) range for smaller regional airliners and extend up to about 160 knots (182mph) for a heavy transport jet.

Some though, like small business jets approach even slower as they are considerably lighter and therefore do not need to make as much lift to maintain flight. And some, like a military F-16 approach significatly faster as they have no high-lift devices installed on the leading egdes of the wings to allow them to slow down

Technorati Tags: Airliners, Airplane Aircraft, Airspeed, Approach Speed, Business Jets, Downside, Heavy Transport, jet airplane, Knots, Lot, Small Business, Touchdown, Transport Jet, Wings

when an airplane is flying how does the speed increase or decrease? does it work on the newtron’s 3rd law?

There are a lot of good answers here, Yes – both 1.increasing the throttle and 2. lowering the nose should increase airspeed,
but I think your question was subtley asking how low flying affects airspeed.

I think what you are alluding to is what is called "ground effect". When an airplane or helicopter is low enough (1/2 to 1 wingspan or less for an airplane or 1/2 rotor diameter for a helicopter),
ground effect produces more lift. You are able to have higher acceleration and airspeed as less energy is required for "lift". That is because the hard or liquid surface is pushing back at you, better than a volume of air can.

An aircraft’s top speed is actually likely to occur at a higher altitude where the air is thinner, but acceleration in ground effect, is greater than acceleration in level flight at 500 feet. Optimum altitudes are different for each airplane and found in the POH, which is like an owners manual, for each airplane, and are ususally thousands of feet above sea level.

As an aside, pilots have to be careful of getting overconfident with the effects of ground effect in high altitude flying, as airplanes will become airbourne at slower speeds than they will need to keep from wingstall once they get out of ground effect. Big Bear Airport, in California, at 6748 ft. / 2056.8 m, is a prime example http://www.bigbearcityairport.com/ . On a hot day the air is very thing and pilots can take off and then climb a bit into a stall and end up landing in the lake. Talk about soggy sandwiches!

Hovercraft rely on ground effect and could not normally fly higher. The Russians had huge planes that would only fly in ground effect above the water in the Caspian Sea http://en.wikipedia.org/wiki/Ekranoplan . I know of one experienced pilot that was ferrying a small twin engine airplane from Hawaii to California. When one engine went out, he descended to about 5 meters and flew on one engine the rest of the way, sometimes getting a little ocean spray.

P.S. Yes, Newton’s law is valid for this. F = ma
There are four forces operating on an aircraft:
Lift, Drag, Gravity, Thrust.
In ground effect, there is more lift because for every action, there is an equal and opposite reaction and pushing on the ground – which can’t move, gets more direct reaction than pushing on air particles that can move AND
2. The drag is less out higher altitudes, because of thinner air, there is less friction, so higher altitudes can be optimal.

Unfortunately the engine performs less well, unless it’s turbo charged or a jet, so at some point there will be an optimum altitude for speed.

Technorati Tags: Airspeed, Altitudes, Bear Airport, Big Bear, Caspian Sea, Feet Above Sea Level, Ground Effect, High Altitude, Hot Day, Level Flight, Liquid Surface, Newtron, Poh, Prime Example, Rotor Diameter, Soggy Sandwiches, Speed Increase, Twin Engine Airplane, Wikipedia, Wingspan