Planes are grounded due to heavy heat, unstable air layers in the sky and flight paths that are expected to change - the climate crisis also affects the aviation industry
By Assaf Ben Naria, Zivata, Science and Environment News Agency
27 injured passengers, some with fractures and severe bruises - these were the results of a flight between Moscow and Bangkok that was supposed to be quite routine. The Boeing 777 of the Russian airline Aeroflot was only 40 minutes away from the Bangkok airport, when it suddenly dropped and shook in the air for many seconds. "Blood on the ceiling, people with broken noses, injured babies", is how one of the passengers described what happened in those seconds to the reporter CNN. "It came out of nowhere, the plane jumped in all directions. It felt like driving in a car where one of the wheels suddenly explodes."
According to the airline's statement, the cause of the severe shaking experienced by the plane is passage through an unstable air layer - turbulence. Currently, there are no accurate means that can predict the exact location of the turbulent sky, which explains the fact that the seat belt light did not come on at all before the Russian plane began to dance in the air. For this very reason, after reaching cruising altitude, the pilot will usually advise passengers to fasten their seat belts as long as they are seated. If until now you haven't paid attention to the captain's message on the subject, perhaps to start listening to him, because climate change will make the flights of the future much more bouncy, according toA recently published study.
Hotter - more shaking
The connection between climate change and the aviation industry that emerges from the new research is further proof that the global climate crisis is not only the problem of some remote island residents that the sea threatens to cover, but affects the lives of all of us - at sea, on land and in the air. Indeed, an increase in the frequency and intensity of extreme weather events as a result of climate change threatens the aviation industry, which is affected by the climate more than any other type of transportation. as per US Department of Transportation, flight delays related to extreme weather are the biggest cause of flight delays today. Only recently, for example, American Airlines had to cancel many flights after the air temperature at the airport in Arizona in the United States reached 48 degrees.
study who examined the effect of the warming of the air temperature on the surface of the earth, and the increase in the number of extreme heat events, found that this would have serious consequences for airplanes, especially when it comes to fields with short runways and relatively small airplanes. The study looked at four major airports in the US and found that the number of days on which take-off weight restrictions will be applied is expected to increase by 200 percent in the next 30-50 years compared to today. In Phoenix, the capital of Arizona, for example, the number of restriction days is expected to increase from zero today to 20 in 2050.
And as we have already seen, if the plane gets permission to take off, it is expected to fall into an unstable air layer. study which was published last May warns that with the increase in the concentration of carbon dioxide in the atmosphere, as a result of the global climate crisis, the frequency of cases in which the plane will encounter turbulent air currents (Clear Air Turbulence) during the flight will increase. While theStudies Predecessors indicated a connection between climate change and an increase in cases of severe to severe turbulence, the current study found that the increase will be in all levels of severity of the turbulence - from mild to severe. The research examines a scenario in which the concentration of carbon dioxide in the atmosphere is doubled compared to the pre-industrial era, which according to Evaluations Variation may occur as early as the end of this century. In light of the fact that the concentration of carbon dioxide in the air, measured continuously on Mt Mauna Loa In Hawaii, which has long since crossed the 400 ppm mark and is now approaching 410 parts per million, this scenario seems more realistic than ever.
The researchers found that in an atmosphere with double the concentration of greenhouse gases, the number of times a passenger plane will encounter air with turbulence defined as "mild" will increase by 59 percent. Turbulence of the light type is also the most common, therefore it is a significant figure with consequences for the comfort of the passengers in the flight and the costs of the flight, since turbulent air increases the fuel consumption of the plane and sometimes also forces the pilot to change the route during the flight.
A jump of 30 meters in the air
According to the model used by the researchers, the cases in which the pilot will be forced to maneuver through moderate turbulence will double, while the number of cases of severe turbulence is expected to be multiplied 1.5 times. The latter figure will have an impact not only on passenger comfort, but also on their safety, as severe turbulence can cause mechanical damage to the aircraft.
Turbulence describes a state of unstable air, and it often results from vertical air currents or areas with low pressure ("air pockets"). Pilots have difficulty avoiding entering turbulence, because it often disappears from the plane's satellite and warning systems, and of course also from the pilot's eyes.
The turbulences are classified according to their severity. The light type is characterized by slight vibrations and vertical movement of the plane up or down a few meters, and apart from the temporary discomfort, there is usually no danger to the passengers or the plane in this situation. Turbulence of moderate severity, however, currently occurs once every few thousand flight hours. In such a case, the aircraft may deviate about ten meters up or down, which may cause a feeling of discomfort among the passengers. Severe turbulence is much rarer, in which the plane may jump up to a height of 30 meters in a very short period of time. In these cases, passengers who are not wearing seat belts may be injured, and several deaths have even been recorded over the years.
At the height where most civil flights fly, there are fast air currents called the jet streams. Most of the jet streams on Earth are from west to east, and planes sometimes use these streams to shorten flight times (therefore a flight from New York to Tel Aviv will sometimes be shorter than the opposite route). Researchers believe that climate change will also affect the jet streams and their shift towards the transatlantic flight paths that are common today. The air at the edges of the jet streams is unstable, and that is where the areas exposed to turbulence will most often be found. Therefore, with the change in the currents, the researchers predict that the planes - and those who fly in them - will meet them with much greater frequency in the not-too-distant future.
22 תגובות
Israel
I don't know helicopter figures but hovering uses a lot of fuel, and high hovering uses much more. The reason for the low efficiency is the flow regime around the rotor. This is not fundamentally different from the situation in a fixed-wing aircraft at slow speed.
In forward flight the helicopter advances into stagnant air. In hover the compressed air below the rotor is drawn into the low pressure above it. There is a donut of vortices around the rotor that causes a vertical wind to drop - meaning the smaller the angle of attack.
At low altitude, the ground interferes with this vortex and reduces the effect. The same phenomenon exists when landing in civilian airplanes - a certain increase in ground effect lift.
Right..
So for all the Wagers - engines, propellers, Amayat - if every balloon can stay in the air for years without burning a single candle?
And after all, in reality, how much energy do you really need to burn to keep 10 tons in the air for an hour? (not that I know) and why so many (although I don't know how much)?
Israel
I think the minimum power is 0.
It is also worth adding in the matter of the propeller as a rotating wing the issue of the wing profile and the angle of attack: we see that in slow planes the profile is thick and the angle of attack - the inclination of the wing in relation to the direction of flight - is high. This is how you get maximum lift.
In the rotating propeller, the speed increases in direct proportion to the distance from the axis of rotation, as in any wheel. Therefore, in the propeller near the axis, the profile is thick and the angle of attack is high, and the profile gets narrower and the angle of attack gets smaller towards the end, in order to get an optimal thrust in relation to the engine power.
And now a little kitbag question: theoretically, in terms of pure physics, what is the minimum engine power needed to keep a 10-ton helicopter floating in the air?
א
Regarding the F-22 (and other modern planes like the Typhoon): there is a trick in these engines - the receiver reduces the speed of the air entering the fan. The air is accelerated, then the nozzle raises the speed of the air to supersonic, faster than the air entering the receiver. There is another complication here due to the fact that the speed of sound depends on the temperature of the gas, but this is not important at the moment.
Note Newton's second law: impulse is mass multiplied by velocity. We are not interested in temperature or pressure. Of course, if we take a vessel with a hole and heat gas in it, then the increase in temperature will increase the pressure of the gas and then it will be ejected from the hole and create an impulse. But you have to find a way to refill the vessel. This is basically what happens in a jet engine - the exhaust gases from the combustion chamber turn a turbine that turns a compressor that puts air into the combustion chamber.
א
I will try to clarify the issue of the propeller. Take something like a Beasley Grill (which looks like a screw) and a bucket full of jelly. Screw in the Beesley at a rate of one revolution per second. If the beesley is free and the distance between the windings is 6 mm then the beesley will advance 6 mm per second, right? If you stop the Beesley from moving then it will force the Jelly to move backwards, like you drill into a tree if you drill a spiral.
If you try to push the Bisley forward faster than 6 mm per second then there will be resistance right?
Maybe it's easier to imagine driving a screw into wood. Everyone and their own imagination 🙂
This is a very rough explanation, but good enough to understand the speed limit of each propeller.
What I said about an explosion was only intended to demonstrate that in terms of the energy source alone there is almost no limit to the speed at which the energy in the fuel can be released (of course there is a limit in terms of the engine)
I didn't fully understand how a ship's propeller that spins too fast slows it down. And I didn't understand whether this is a real limitation or something that can always be solved by the structure of an engine. If I understood correctly, it is even possible to exceed the speed of sound without using burners, for example in the f-22 (by dry engine you mean without a burner so that the thrust is created only from rotation?) In any case, my main question is about passenger planes.
Another thing, you said that today it is not possible to compress air with the intensity of pressure created by the combustion of a burner. Sounds logical, but is it possible to produce the pressure by heating air (electrically) as is done in combustion?
א
No propulsion system that I know of relies on an explosion - not even a cannon shell or a rifle bullet. In a pilot you need a relatively constant thrust.
There are basically two ways to generate thrust in an aircraft - a propeller or a stream of gases. Let's close the propeller issue first.
You can look at a propeller as a rotating wing. The lift on a wing depends on two factors (I'm simplifying to emphasize what's important): speed and angle of attack. This angle is the angle between the wing chord (roughly an imaginary line from the front of the wing to the back) and the relative wind, and has a maximum value that must not be exceeded. In the propeller, the relative wind depends on the ratio between the rotation speed and the flight speed. To visualize this, think of a ship's propeller and turn it at a constant rate. At slow speed the propeller pushes water backwards, but at a certain speed the propeller just "screws" into the water. At a higher speed, the propeller will actually slow down the ship!
That is - there is a final speed of an aircraft with a propeller. A turbofan engine is not fundamentally different. In such an engine, the propeller is inside a receiver, and the receiver is built so that it slows down the speed of the air entering the engine. For example, in the F-15/16, the air reaching the fan is always subsonic, even though the plane can fly supersonic.
In principle - there is no problem for an electric motor to turn the engine of a fighter plane such as the F-15/16, but the motor will only operate in the dry area (that is, up to half of the maximum thrust).
The flow of gases is very simple to understand - all you need is Newton's second law. This is the principle of fanless jet engines, burner mode and rocket engines. In principle, it is possible to build an electric compressor that will not be limited by the problems of the propeller (for example - a piston compressor), but this is a bit futuristic.
Miracles
I guess the problem is not only in the energy to inflate these but also in the possible power. Fuel as a principle can release all its energy in one moment (explosion like in the Twin Towers)
I guess the battery has a limitation in this regard (on the other hand, there is also supercapacitor technology)
But let's talk regardless of the source of the electric current.
If I understand correctly airliner jet engines are of the turbo fan type. If I understood correctly, it mainly uses the rotation of the shaft for thrust. So is there a problem in principle with rotating the fan with an electric motor or does an electric motor have an upper limit of power.
And one more thing, apart from creating a rotation by magnetic fields, is there no other option for propulsion with electricity?
א
Today, the amount of energy per volume unit of electric batteries competes well with liquid fuel, and soon the weight will also compete. So in terms of carrying weight for the range there is a lot to talk about.
But, electricity today can only turn a propeller, and the thrust of a propeller decreases with speed. To get high thrust at high speed you need a jet or rocket engine.
Miracles
Not really related to the article but about aviation.
I wanted to ask a question
Following a discussion on another website about an article in which an electric plane was presented. Of course a light plane and similar to piston planes.
And the question arose as to whether an electric engine with performance similar to jet engines is even possible. (I'm not necessarily talking about a mature technology, but at least something that was presented under laboratory conditions, actually also a theoretical idea) Intuitively, it seems not.
my father
The t-n-t-k shelf... it didn't slide from the land to the sea. Even when it melts, the sea level will not rise, but the danger is different. The white ice reflects most of the sun's radiation, but after it melts this will no longer happen.
The rate of warming is higher than you said, between 2 times 6. According to what you say, the earth has already warmed 0.5 degrees in my lifetime. Do you even understand what half a degree means in the whole world? We live in a very delicate balance, and half of it has a huge meaning!! Add to that the number of people in the world more than doubled during this period, the forest cover also decreased a lot.
Father, you should open your eyes. The earth is not in danger, but the lives of your grandchildren definitely are!
Correction - according to the photographs that were published it seems that the surface is still in place and it just broke, if it is sitting on land as you claim then yes, as soon as it slides into the sea the water level will rise a little.
Avi,
Are you claiming that this ice shelf sat on land and slid off it sideways into the ocean? are you sure about that In any case it hasn't melted yet, so why would the water level change? Look at the photos, it's still intact...
And I am not against the theory of global warming, I am against these exaggerations which, in my opinion, only increase the distrust of those who do not believe in it.
to the opponent
The aforementioned ice shelf broke off from the Antarctic continent above the continent, so according to the scientists it was supposed to raise the level.
Avi,
The ice shelf that broke off floats on the surface of the water and therefore even if it all melts the water level will not change (put a large ice cube in a glass of water and let it melt, you will see that the water level will not change). The fear, as far as I understand it, is that this ice shelf is only the first swallow, and as the ice surface at the poles gets smaller and smaller, there will be less white surface that reflects the sun's radiation, and more sea area that absorbs the sun's radiation and contributes to global warming.
What can raise the water level are glaciers that sit on solid ground and on mountain peaks, when they melt and flow into the oceans the level will probably rise.
And yesterday I saw an article on the news on one of the "serious" channels that the war in Syria is also a result of the climate crisis.
To remind you, we all agree that there is global warming, and that it is due to an increase in the concentration of CO2 in the air...
But in the meantime it is an average increase of one tenth of a degree in ten years, which can only be measured with special equipment.
And in the meantime, the ice shelf in Antarctica that was immediately feared broke away - what happened to the sea level?.
Herzl
This is true. There is also danger at height, but the danger is significantly higher when landing.
Nissim: You are right. Only near the airport it usually ends in a crash because of the low altitude.
Herzl
The problem is that such systems detect wind shear only in the field area. I don't know of a system that can detect CAT at altitude, and certainly not wherever you fly.
Indeed, there are means for detecting shear winds and turbulence. At the airport of Denver, Colorado, USA, laser radars (LIDAR - LASER RADAR) have been installed for about 20 years. They measure the air currents in the field area and alert the control. I assume that while in the fields this equipment is installed, but I know that Denver was the first installation. About 30 years ago, a passenger plane crashed in Colorado due to wind shear.