Malaysian Airlines Flight 370

Posted by PITHOCRATES - March 16th, 2014

Week in Review

There are a lot of airplanes in the air at any given time.  And, remarkably, over 99% of those planes reach their destinations safely.  So when one doesn’t it’s big news.  Such as Malaysian Airlines Flight 370.  A plane that has been missing since March 8, 2014.  Ten days as of this writing.  And still no one knows what happened.  There’s been a lot of speculation.  From pilot suicide to fire to electrical failure to catastrophic mechanical failure to a high jacking to piracy.  Some have even suggested that it may have been a trial run by terrorists to test a new terror plot.  To see the problems they may encounter.  And to see what the response would be.  If it wasn’t it might as well had been.  As all the speculators have given a wealth of information that terrorists might have gained had it been a trial run.

So what do we know?  Concretely?  The plane and the people aboard are missing.  Which is the only absolute we know.  Now what plausible assumptions can we make?  The plane crashed and we haven’t found it yet.  Or the plane was stolen.  For some future use.  If it crashed it is imperative to find it should there be an unknown issue with the Boeing 777.  An incredibly safe airliner to date.  And very popular with the airlines for their long-haul routes.  So if there is an unknown issue we need to know because there are so many of these flying.

Perhaps the more disturbing assumption is that it was stolen.  Because it is an intercontinental jetliner.  North Korea has missiles that can reach the United States.  Saddam Hussein had scud missiles that could reach Israel.  Iran has a nuclear program.  But may not have long-range missile technology.  A 777 provides long-range capability.  And if it was stolen it would be hard to blame any state for what may happen if that plane was used for some nefarious purpose.  As there would be no flight plan filed tracing it back to a departing airport.  Which is even a greater incentive to find it.  As a lot of people are talking about this possibility one would assume that great attention is being placed on runways long enough for a refueled 777 to take off from.  Which would be longer than one needed to land a 777 low on fuel.  And one could also assume that airborne radar is being used to try and catch anyone trying to fly at night below radar coverage.  Giving ample warning to scramble fighter jets to intercept the threat.  And shooting it down if necessary.  So even if it turns out that the airplane was stolen it would be very difficult to use that airplane for nefarious purposes.  But not impossible.

There would be a lot less speculation had that transponder remained turned on.  For if we can ‘see’ the airplane we know where it is.  A rather simple device that tells air traffic control everything they need to know about an airplane.  Which is important considering how many airplanes are in the sky at any one time.  Just to get an idea of how many you can watch a visualization of all air traffic over European airspace (see Watch an Entire Day of Air Traffic in One Astonishing Visualization by Kyle VanHemert posted 3/14/2014 on Wired).  So perhaps ‘hardening’ the transponder is the first thing we should be doing.  Something that can probably be done for little cost.  Say adding a rechargeable battery to the transponder that is only accessible from outside the aircraft.  So it is inaccessible during flight.  If the transponder is switched off and it transfers to battery it could broadcast the high jacking code.  While providing the plane’s location.  If the plane has a catastrophic breakup in flight the transponder could be in a hardened shell that keeps broadcasting during and after this event on battery power.  It may add some weight.  And some cost.  But if it can provide an aircraft’s location after an event it may prevent some of the uncertainty in future events like there is with Malaysian Airlines Flight 370.


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Aviation Incidents and Accidents

Posted by PITHOCRATES - March 12th, 2014

Technology 101

The Pilots of Aloha Airlines Flight 243 landed Safely after Fatigue Cracks caused Part of the Cabin to Disintegrate

The de Havilland Company introduced the jet airliner to the world.  The Comet.  A 4-engine jet airliner with a pressurized cabin that could carry 36 passengers.  It could fly at 40,000 feet at speeds close to 500 mph.  Just blowing the piston-engine competition away.  Until, that is, they started breaking up in flight.  A consequence of pressuring the cabin.  The inflating and deflating of the metal cabin fatiguing the metal of the cabin.  Until fatigue cracks appeared at stress points.  Cracks that extended from the cycles of pressurizing and depressurizing the cabin.  Until the cracks extended so much that the pressure inside the cabin blew through the cracks, disintegrating the plane in flight.

Japan is a nation of islands.  Connecting these islands together are airplanes.  They use jumbo jets like buses and commuter trains.  Packing them with 500+ passengers for short hops between the islands.  Putting far more pressurization cycles on these planes than typical long-haul 747 routes.  On August 12, 1985, Japan Airlines Flight 123 left Haneda Airport, Tokyo, for a routine flight to Osaka.  Shortly after takeoff as the cabin pressurized the rear pressure bulkhead failed (due to an improper repair splice of the pressure plate using a single row of rivets instead of a double row following a tail strike that damaged it).  The rapid force of the depressurization blew out through the tail section of the aircraft.  Causing great damage of the control surfaces.  And severing the lines in all four hydraulic systems.  Leaving the plane uncontrollable.  The crew switched their transponder to the emergency code 7700 and called in to declare an emergency.  But they could do little to save the plane.  The plane flew erratically and lost altitude until it crashed into a mountain.  Killing all but 4 of the 524 aboard.

Hawaii is similar to Japan.  They both have islands they interconnect with airplanes.  Putting a lot of pressurization cycles on these planes.  On April 28, 1988, Aloha Airlines Flight 243 left Hilo Airport bound for Honolulu.  Just as the Boeing 737 leveled off at 24,000 feet there was a loud explosive sound and a loud surge of air.  The pilots were thrown back in their seats in a violent and rapid decompression.  The flightdeck door was sucked away.  Looking behind them they could see the cabin ceiling in first class was no longer there (due to fatigue cracks radiating out from rivets that caused pressurized air to blow out, taking the ceiling and walls of the first class cabin with it).  They could see only blue sky.  They put on their oxygen masks and began an emergency descent.  The first officer switched the transponder to emergency code 7700.  The roar of air was so loud the pilots could barely hear each other as they shouted to each other or used the radio.  The flight controls were operable but not normal.  They even lost one of their two engines.  But the flight crew landed safely.  With the loss of only one life.  A flight attendant that was sucked out of the aircraft during the explosive decompression.

The Fact that 185 People survived the United Airlines 232 Crash is a Testament to the Extraordinary Skill of those Pilots

On June 12, 1972, American Airlines Flight 96 left Detroit Metropolitan Airport for Buffalo after arriving from Los Angeles.  The McDonnell Douglas DC-10 took on new living passengers in Detroit.  As well as one deceased passenger in a coffin.  Which was loaded in the rear cargo hold.  As the DC-10 approached 12,000 feet there was a loud explosive sound.  Then the flightdeck door was sucked away and the pilots were thrown back in their seats in an explosive decompression.  The aft cargo door (improperly latched—its design was later revised to prevent improperly latching in the future) had blown out as the cargo hold pressurized.  As it did the rapid decompression collapsed the floor above.  Into the control cabling.  The rudder was slammed fully left.  All three throttle levels slammed closed.  The elevator control was greatly inhibited.  The plane lost a lot of its flight controls but the pilots were able to bring the plane back to Detroit.  Using asymmetric thrust of the two wing-mounted engines and ailerons to compensate for the deflected rudder.  And both pilots pulling back hard on the yoke to move the elevator.  Due to the damage the approach was fast and low.  When they landed they applied reverse thrust to slow down the fast aircraft.  At that speed, though, the deflected rudder pulled them off the runway towards the terminal buildings.  By reapplying asymmetric thrust the pilot was able to straighten the aircraft out on the grass.  As the speed declined the rudder force decreased and the pilot was able to steer the plane back on the runway.  There was no loss of life.

On July 19, 1989, United Airlines Flight 232 took off from Stapleton International Airport in Denver for Chicago.  About an hour into the flight there was a loud bang from the rear of the plane.  The aircraft shuddered.  The instruments showed that the tail-mounted engine had failed.  As the crew responded to that the second officer saw something more alarming.  Hydraulic pressure and fluid quantity in the three hydraulic systems were falling (a fan disc in the tail-mounted engine disintegrating and exploded like shrapnel from an undetected manufacturing flaw, taking out the 3 hydraulic systems).  The flight crew soon discovered that they had lost all control of the airplane.  The plane was making a slight turn when the engine failed.  And the flight control surfaces were locked in that position.  The captain reduced power on the left engine to stop the plane from turning.  The two remaining engines became the only means of control they had.  Another DC-10 pilot traveling as a passenger came forward and offered his assistance.  He knelt on the floor behind the throttle levels and adjusted them continuously to regain control of the plane.  He tried to dampen the rising and falling of the plane (moving like a ship rolling on the ocean).  As well as turn the aircraft onto a course that would take them to an emergency landing at Sioux City.  They almost made it.  Unfortunately that rolling motion tipped the left wing down just before touchdown.  It struck the ground.  And caused the plane to roll and crash.  Killing 111 of the 296 aboard.  It was a remarkable feat of flying, though.  Which couldn’t be duplicated in the simulator given the same system failures.  As flight control by engine thrust alone cannot provide reliable flight control.  The fact that 185 people survived this crash is a testament to the extraordinary skill of those pilots.

On July 17, 1996, TWA Flight 800 took off from JFK Airport bound for Rome.  About 12 minutes into the flight the crew acknowledged air traffic control (ATC) instructions to climb to 15,000 feet.  It was the last anyone heard from TWA 800.  About 38 seconds later another airplane in the sky reported seeing an explosion and a fire ball falling into the water.  About where TWA 800 was.  ATC then tried to contact TWA 800.  “TWA800, Center…TWA eight zero zero, if you can hear Center, ident…TWA800, Center…TWA800, if you can hear Center, ident…TWA800, Center.”  There was no response.  The plane was there one minute and gone the next.  There was no distress call.  Nothing.  The crash investigation determined that an air-fuel mixture in the center fuel tank was heated by air conditioner units mounted below the tank, creating a high-pressure, explosive vapor in the tank that was ignited by an electrical spark.  The explosion broke the plane apart in flight killing all 230 aboard.

The Greatest Danger in Flying Today may be Pilots Trusting their Computers more than their Piloting Skills

On December 29, 1972, Eastern Airlines Flight 401 left JFK bound for Miami.  Flight 401 was a brand new Lockheed L-1011 TriStar.  One of the new wide-body jets to enter service along with the Boeing 747 and the McDonnell Douglas DC-10.  Not only was it big but it had the latest in automatic flight control systems.  As Flight 401 turned on final approach they lowered their landing gear.  When the three landing gear are down and locked for landing there are three green indicating lights displayed on the flightdeck on the first officer’s side.  On this night there were only 2 green lights.  Indicating that the nose wheel was not down.  So they contacted ATC with their problem and proceeded to circle the airport until they resolved the problem.  ATC told them to climb to 2000 feet.  The 1st officer flew the aircraft on the course around the airport.  The captain then tried to reach the indicating light to see if it was a burnt out lamp.  Then the flight engineer got involved.  As did the first officer after turning on the automatic altitude hold control.  Then another person on the flightdeck joined in.  That indicating lamp got everyone’s full attention.  Unable to determine if the lamp was burnt out the pilot instructed the flight engineer to climb down into the avionics bay below the flightdeck to visually confirm the nose gear was down and locked.  He reported that he couldn’t see it.  So the other guy on the flightdeck joined him.  During all of this someone bumped the yoke with enough pressure to release the automatic altitude hold but no one noticed.  The airplane began a gradual descent.  When they approached the ground a ground proximity warming went off and they checked their altitude.  Their altimeters didn’t agree with the autopilot setting.  Just as they were asking each other what was going on the aircraft crashed into the everglades.  Killing 101 of the 176 on board.

On June 1, 2009, Air France Flight 447 was en route from Rio de Janeiro to Paris.  This was a fly-by-wire Airbus A330 aircraft.  With side stick controllers (i.e., joysticks) instead of the traditional wheel and yoke controls.  The A330 had sophisticated automatic flight controls.  They practically flew the plane by themselves.  With pilots spending more of their time monitoring and inputting inputs to these systems than flying.  Flight 447 flew into some turbulence.  The autopilot disengaged.  The aircraft began to roll from the turbulence.  The pilot tried to null these out but over compensated.  At the same time he pitched the nose up abruptly, slowing the airplane and causing a stall warning as the excessive angle of attack slowed the plane from 274 knots to 52 knots.  The pilot got the rolling under control but due to the excessive angle of attack the plane was gaining a lot of altitude.  The pitot tube (a speed sensing device) began to ice up, reducing the size of the opening the air entered.  Changing the airflow into the tube.  Resulting in a speed indication that they were flying faster than they actually were.  The engines were running at 100% power but the nose was pitched up so much that the plane was losing speed and altitude.  There was no accurate air speed indication.  For pilot or autopilot.  The crew failed to follow appropriate procedures for problems with airspeed indication.  And did not understand how to recognize the approach of a stall.  Despite the high speed indicated the plane was actually stalling.   Which it did.  And fell from 38,000 feet in 3 and a half minutes.  Crashing into the ocean.  Killing all 228 on board.

It takes a lot to bring an airplane down from the sky.  And when it happens it is usually the last in a chain of events.  Where each individual event in the chain could not have brought the plane down.  But when taken together they can.  Most times pilots have a chance to save the aircraft.  Especially the stick and rudder pilots.  Who gained a lot of flying experience before the advanced autopilot systems of today.  And can feel what the airplane is doing through the touch of their hand on the yoke and through the seat of their pants.  They are tuned in to the engine noise and the environment around them.  Processing continuous sensations and sounds as well as studying their instruments and the airspace in front of them.  Because they flew the airplane.  Not the computers.  Allowing them to take immediate action instead of trying to figure out what was happening with the computers.  Losing precious time when additional seconds could trigger that last event in a chain of events that ends in the loss of the aircraft.  That’s why some of the best pilots come from this stick and rudder generation.  Such as Aloha Airlines Flight 243, American Airlines Flight 96 and United Airlines Flight 232.  Sometimes the event is so sudden or so catastrophic that there is nothing a pilot can do to save the aircraft.  Such as Japan Airlines Flight 123 and TWA Flight 800.  And sometimes pilots rely so much on automated systems that they let themselves get distracted from the business of flying.  Even the best stick and rudder pilots adjusting to new technology.  Such as Eastern Airlines Flight 401.  Or pilots brought up on the new technology.  Such as Air France Flight 447.  But these events are so rare that when a plane does fall out of the sky it is big news.  Because it rarely happens.  Planes have never been safer.  Which may now be the greatest danger in flying.  A false sense of security.  Which may allow a chain of events to end in a plane falling down from the sky.  As pilots rely more and more on computers to fly our airplanes they may step in too late to fix a problem.  Or not at all.  Trusting those computers more than their piloting skills.


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Feedback Loop Control System

Posted by PITHOCRATES - October 30th, 2013

Technology 101

Living through Winters became easier with Thermostats

When man discovered how to make fire it changed where we could live.  We no longer had to follow the food south when winter came.  We could stay through the winter.  And build a home.  As long as we could store enough food for the winter.  And had fire to stay warm.  To prevent our dying from exposure to the cold.

There’s nothing like sitting around a campfire.  It’s warm.  And cozy.  In large part because it’s outside.  So the smoke, soot and ash stayed outside.  It wasn’t always like that, though.  We used to bring that campfire inside the home.  With a hole in the roof for the smoke.  And families slept around the fire.  Together.  Even as some fornicated.  To propagate the species.  But that wasn’t the worst part about living around an indoor campfire.

Your distance from the fire determined how hot or cold you were.  And it was very hot by it.  Not so hot away from it.  Especially with a hole in the roof.  Worst, everyone got colder as the fire burned out.  Meaning someone had to get up to start a new fire.  The hard way.  Creating an ember.  Using it to start some kindling burning.  Then adding larger sticks and branches onto the kindling until they started to burn.  Which was a lot harder than turning the thermostat to ‘heat’ at the beginning of the heating season and forgetting about it.  Then turning it to ‘off’ at the end of the heating season.

A Feedback Loop Control System measures the Output of a System and Compares it to a Desired Output

Replacing the indoor campfire with a boiler or furnace made life a lot simpler.  For with a supply of fuel (natural gas, fuel oil, electricity, etc.) the fire never burned itself out.  And you never had to get up to start a new one.  Of course, that created another problem.  Shutting it off.

Boilers and furnaces are very efficient today.  They produce a lot of heat.  And if you let them run all day long it would become like a hot summer day inside your house.  Something we don’t want.  Which is why we use air conditioners on hot summer days.  So heating systems can’t run all day long.  But we can’t keep getting up all night to turn it off when we’re too hot.  And turning it back on when we’re too cold.  Which is why we developed the feedback loop control system.

We did not develop the feedback loop control system for our heating systems.  Our heating systems are just one of many things we control with a feedback loop control system.  Which is basically measuring the output of a system and comparing it to a desired output.  For example, if we want to sleep under a cozy warm blanket we may set the ‘set-point’ to 68 degrees (on the thermostat).  The heating system will run and measure the actual temperature (at the thermostat) and compare it to the desired set-point.  That’s the feedback loop.  If the actual temperature is below the desired set-point (68 degrees in our example) the heat stays on.  Once the actual temperature equals the set-point the heat shuts off.

The Autopilot System includes Independent Control Systems for Speed, Heading and Altitude

Speed control on a car is another example of a feedback loop control system.  But this control system is a little more complex than a thermostat turning a heating system on and off.  As it doesn’t shut the engine off once the car reaches the set-point speed.  If it did the speed would immediately begin to fall below the set-point.  Also, a car’s speed varies due to terrain.  Gravity speeds the car when it’s going downhill.  And slows it down when it’s going uphill.  The speed controller continuously measures the car’s actual speed and subtracts it from the set-point.  If the number is negative the controller moves the vehicle’s throttle one way.  If it’s positive it moves the throttle in the other way.  The greater the difference the greater the movement.  And it keeps making these speed ‘corrections’ until the difference between the actual speed and the set-point is reduced to zero.

Though more complex than a heating thermostat the speed control on a car is pretty simple.  It has one input (speed).  And one output (throttle adjustment).  Now an airplane has a far more complex control system.  Often called just ‘autopilot’.  When it is actually multiple systems.  There is an auto-speed system that measures air speed and adjusts engine throttles.  There is a heading control system that measures the aircraft’s heading and adjusts the ailerons to adjust course heading.  There is an altitude control system that measures altitude and adjusts the elevators to adjust altitude.  And systems that measure and correct pitch and yaw.  Pilots enter set-points for each of these in the autopilot console.  And these control systems constantly measure actual readings (speed, heading and altitude) and compares them to the set-points in the autopilot console and adjusts the appropriate flight controls as necessary. 

Unlike a car or an airplane a building doesn’t move from point A to point B.  Yet they often have more complex control systems than autopilot systems on airplanes.  With thousands of inputs and outputs.  For example, in the summer there’s chilled water temperature, heating hot water temperature (for the summer boiler), supply air pressure, return air pressure, outdoor air pressure, indoor air pressure, outdoor temperature, outdoor humidity, indoor temperature (at numerous locations), indoor humidity, etc.  Thousands of inputs.  And thousands of outputs.  And unlike an airplane these are all integrated into one control system.  To produce a comfortable temperature in the building.  Maintain indoor air quality.  Keep humidity levels below what is uncomfortable and possibly damaging to electronic systems.  And prevent mold from growing.  But not keep it too dry that people suffer static sparks, dry eyes, dry nasal cavities that can lead to nose bleeds, dry and cracked skin, etc.  To prevent a blast of air hitting people when they open a door.  To keep the cold winter air from entering the building through cracks and spaces around doors and windows.  And a whole lot more.  Far more than the thermostat in our homes that turns our heating system on and off.


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Aircraft De-Icing Systems

Posted by PITHOCRATES - October 23rd, 2013

Technology 101

A build-up of Ice on Airfoils causes a Reduction of Lift and a Loss of Stability

In the classic movie Airport (1970) after the guy pulled the trigger on his briefcase bomb the plane suffered a massive decompression.  When Dean Martin got back to the cockpit he told the flight engineer to give them all the heat they had.  Because it’s very cold flying above 10,000 feet without pressurization.  That’s why World War II flight crews wore a lot of heavy clothing and thick mittens in their bombers.  As well as oxygen masks as the air was too thin to breathe.  The B-17 even had open windows for the waste gunners.  Making it very cold inside the plane.  Because the air is very, very cold at altitude.

There is another problem at altitude.  Because of these very frigid temperatures.  Water droplets in the air will freeze to any surface they come into contact with.  They can reduce engine power for both propeller and jet engines.  They can freeze on ports used for instrumentation and give inaccurate readings of vital aircraft data (such as engine pressure ratio, aircraft speed, etc.).  And they can freeze on airfoils (wings, rudder, tail fin, etc.).  Disturbing the airflow on these surfaces.  Causing a reduction of lift and a loss of stability.

Ice and airplanes are two things that don’t go together.  As ice forms on a wing it disturbs the airflow over the surface of the wing.  Increasing drag.  And reducing lift.  Causing the plane to lose speed.  And altitude.  If the ice continues to form on the wing eventually it will stall the wing.  And if the wing stalls (i.e., produces no lift) the plane will simply fall out of the sky.  In the early days of aviation pilots were highly skilled in flying their planes where there were no icing conditions.  Flying over, under or around masses of air containing water droplets in subfreezing temperatures.  Today we have anti-icing systems.

The most common Anti-Icing System on Commercial Jets is a Bleed Air System

One of the most common anti-icing systems on turboprop aircraft is the use of inflatable boots over the leading edge of the wing.  Basically a rubber surface that they can pump air into.  When there is no ice on the wing the boot lies flat on the leading edge without interrupting the airflow.  When ice forms on the leading edge of the wing the boot inflates and expands.  Cracking the ice that formed over it.  Which falls away from the wing.

Commercial jets have larger airfoils.  And require a larger anti-icing system.  The most common being a pneumatic manifold system that ducts hot air to areas subject to icing.  Which works thanks to a property of gas.  If you compress a gas you increase its temperature.  That’s how a diesel engine can work without sparkplugs.  The compressed air-fuel mixture gets so hot it ignites.  This property comes in handy on a jet plane as there is a readily available source of compressed air.  The jet engines.

As the air enters the jet it goes through a series of fast-spinning rotors.  As the air moves through the engine these rotors push this air into smaller and smaller spaces.  Compressing it.  Through a low-pressure compressor.  And then through a high-pressure compressor.  At which time the air temperature can be in excess of 500 degrees Fahrenheit.  It is in the high-pressure compressor that we ‘bleed’ off some of this hot and pressurized air.  We call this a bleed air system.  The air then enters a manifold which ducts it to at-risk icing areas.  From the engine cowling to the wings to the instrumentation ports.  Using the hot air to raise temperatures in these areas above the freezing temperature of water.  Thus preventing the formation of ice.

The Drawback of a Bleed Air System is Reduced Engine Efficiency

The bleed air system does more than just anti-icing.  It also pressurizes the cabin.  As well as keeps it warm.  Which is why we don’t have to dress like a crewmember on a World War II bomber when we fly.  It also powers the air conditioning system.  And the hydraulic system.  It provides the pressure for the water system.  And it even starts the jet engines.  With the source of pressurized bleed air coming from the auxiliary power unit mounted in the tail.  Or from an external ground unit.  Once the jets are running they disconnect from the auxiliary source and run on the bleed air from the engines.

There is one drawback of a bleed air system.  It bleeds air from the jet engine.  Thus reducing the efficiency of the engine.  And a less efficient engine burns more fuel.  Raising the cost of flying.  With high fuel costs and low margins airlines do everything within their power to reduce the consumption of fuel.  Which is why pilots don’t top off their fuel tanks.  They’d like to.  But extra fuel is extra weight which increases fuel consumption.  So they only take on enough fuel to get to their destination with enough reserve to go to an alternate airport.  Even though it seems risky few planes run out of fuel in flight.  Allowing the airlines to stay in business without having to raise ticket prices beyond what most people can afford.

To help airlines squeeze out more costs Boeing designed their 787 Dreamliner to be as light as possible by using more composite material and less metal.  Making it lighter.  They are also using a more efficient engine.  Engines without a bleed air system.  In fact, they eliminated the pneumatic system on the 787.  Converting the pneumatic components to electric.  Such as using electric heating elements for anti-icing.  Thus eliminating the weight of the bleed air manifold and duct system.  As well as increasing engine efficiency.  Because all engine energy goes to making thrust.  Which reduces fuel consumption.  The key to profitability and survival in the airline industry.


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Dirigibles may do the Heavy Lifting in Alaska

Posted by PITHOCRATES - July 28th, 2013

Week in Review

If you’ve watched Ice Road Truckers you’ve learned that it isn’t easy to move freight in Arctic regions.  Like Alaska.  Because there aren’t a lot of roads or bridges in Arctic regions.  Hence the ice roads.  Crossing rivers, lakes and oceans in the winter when they’re frozen over.  But even these roads cover only a fraction of Alaska’s sprawling country.  Which is why the airplane dominates in Alaska.  To move freight.  And people.  Making for some really high transportation costs.  Raising the costs of everything the good people of Alaska buy (see Hometown U: Could blimps find a place in Alaska skies? by Kathleen McCoy, Hometown U, posted 7/27/2013 on Anchorage Daily News).

Rob Harper at AUTC [Alaska University Transportation Center] pointed me to a new study the Center and UAA’s Institute for Social and Economic Research (ISER) partnered on, looking at the effect of higher transportation fuel prices. He called it a true eye-opener on the ever-rising cost of moving goods to and around Alaska. Every household and business is affected. No one thinks fuel prices will go down again.

ISER economists have often looked at spiking heat and electricity costs, but this was a first attempt to document higher transportation costs rippling through Alaska’s economy. In 2010, economist Ginny Fay and her study colleagues reported, Alaska’s per capita energy consumption was triple the national average.

Alaska fuel prices increased more than 25 percent between 2009 and 2010. Consumers responded by buying fewer cars and airplane tickets. They also paid higher prices for everything they did buy, from food to clothing…

Industries that use the most fuel are the hardest hit. In Alaska, that’s aviation, which uses 90 percent of it, Fay wrote.

And this in a state that exports oil.  But while they may be rich in oil reserves they have no refinery capacity.  Which means refined aviation fuel, diesel and gasoline has to be brought into Alaska.  And unlike the lower 48, that get their refined petroleum products via pipelines, Alaska must rely on more costly modes of transportation.  Shipping it over land or over water in smaller batches at greater prices.

Here’s where those slow, graceful dirigibles wedge their way back into our conversation. Being lighter than air thanks to nonflammable helium, and moving much slower than planes, they consume a lot less fuel. One research study for the military in 2009 compared an hour of flight time in an F-16 ($8,000) to an hour of flight time in a dirigible (less than $500).

Traditional air cargo is the most expensive way to move freight on a fuel-cost-per-ton-mile basis. Fay’s analysis showed that rail is cheapest, followed by trucks, then barge, ships and ferries. But Alaska only has 500 miles of rail. Our ships and barges often leave the state less than full, raising the cost per ton-mile. And we only have two roads, one north and one south. Most of Alaska is nowhere near a road or a coastline. So we’re back to air cargo.

Rail is the cheapest way to move heavy freight because of steel wheels on steel rails.  There’s very little friction so locomotives can pull a very long train consist full of heavy freight.  And they move fast.  Day or night.  In any kind of weather.  So they can quickly carry revenue-producing freight nearly around the clock.  Trucks are fast like trains but carry far less per load.  And whereas railroads change out train crews to keep trains rolling around the clock most long-haul trucks are privately owned.  And when the driver reaches his legal limit of driving time per day he or she has to park their rig and rest for a mandatory rest period.  Thus reducing the revenue-miles of trucks compared to trains.

Barges, ships and ferries can carry larger loads than trucks but loading and unloading takes time.  Time they can’t earn revenue.  Also, they travel slower than trains or trucks.  Limiting the amount of revenue-earning trips they can make.  Whereas air cargo is the fastest way to move cargo.  Allowing many revenue-earning trips.  But the planes flying in Alaska carry a fraction of the cargo trains, trucks, barges, ships and ferries can carry.  Greatly increasing the fuel-cost-per-ton-mile.  Which makes the dirigible such an attractive alternative in Arctic regions like Alaska.

The dirigible doesn’t need a road or waterway.  It can travel year round weather permitting.  It’s slow but because it burns so little fuel the cost per trip is nothing compared to an airplane.  It can’t carry as much as a train, barge or ship but it can go where a train, barge or ship can’t.  And it can travel as the crow flies.  A straight line between two points.  Something that only an airplane can do.  But it can do it for a far lower fuel-cost-per-ton-mile than an airplane.

There is little downside of using a dirigible to ship freight in these inhospitable Arctic regions.  Unless you’re a fan of Ice Road Trucking.  For a dirigible could probably carry anything a truck can carry.  And without a road, paved or ice, to boot.  Putting the ice road truckers out of business.


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High-Speed Train crashes in Spain because things moving at High Speeds on the Ground can be Very Dangerous

Posted by PITHOCRATES - July 27th, 2013

Week in Review

Trains are heavy.  Getting a train moving is one thing.  But getting it to stop is another.  Because heavy things moving fast have a lot of kinetic energy.  The energy of something in motion.  In classical mechanics we calculate the kinetic energy by multiplying one half of the mass times the velocity squared.  That last part is really important.  The velocity part.  For as the speed increases the kinetic energy increases by a far greater amount.  For example, a train increasing speed from 30 kilometers per hour (18 mph) to 190 kilometers per hour (114 mph) increases its speed by 533%.  But because we square the velocity the kinetic energy increases by 3,911%.   Making high-speed rail more dangerous than regular rail.  Because of the great amounts of kinetic energy involved.

Airplanes are very heavy.  They travel at great speeds.  And have great amounts of kinetic energy.  Which is why plane crashes or so horrific.  Anything with that amount of kinetic energy suddenly stopping dissipates that energy in great heat, noise and the explosion of solid parts.  But plane crashes, thankfully, are rare.  For when they are travelling at those great speeds they’re up in the air thousands of feet (or more) away from anything they can hit.  And if there is a malfunction they can fall safely though the sky (with enough altitude) until the pilots can recover the aircraft.  For airplanes have the best friend to high speed objects.  A lot of empty space all around them.  Not so with high-speed rail (see Driver in custody after 80 killed in Spain train crash by Teresa Medrano and Tracy Rucinski posted 7/25/2013 on Reuters).

The driver of a Spanish train that derailed, killing at least 80 people, was under police guard in hospital on Thursday after the dramatic accident which an official source said was caused by excessive speed.

The eight-carriage train came off the tracks, hit a wall and caught fire just outside the pilgrimage destination Santiago de Compostela in northwestern Spain on Wednesday night. It was one of Europe’s worst rail disasters…

Video footage from a security camera showed the train, with 247 people on board, hurtling into a concrete wall at the side of the track as carriages jack-knifed and the engine overturned…

El Pais newspaper said the driver told the railway station by radio after being trapped in his cabin that the train entered the bend at 190 kilometers per hour (120 mph). An official source said the speed limit on that stretch of twin track, laid in 2011, was 80 kph…

Investigators were trying to find out why the train was going so fast and why security devices to keep speed within permitted limits had not slowed the train…

Spain’s rail safety record is better than the European average, ranking 18th out of 27 countries in terms of railway deaths per kilometers traveled, the European Railway Agency said. There were 218 train accidents in Spain between 2008-2011, well below the EU average of 426 for the same period.

There are no rails to derail from in the air.  And no concrete walls to crash into.  Air travel requires no infrastructure between terminal points.  High-speed rail travel requires a very expensive, a very precise and a highly maintained infrastructure between terminal points.  As well as precise controls to keep the train from exceeding safe speeds.  Planes do, too.  But when you have thousands of feet of nothingness all around you there is time to make adjustments before something catastrophic happens.  Like derailing when speeding through a curve too fast.

Air travel is safer than high-speed rail travel.  Which is why when a plane crashes it’s big news.  Because it happens so rarely these days.  Thanks to good aircraft designs.  Good pilots.  And having thousands of feet of nothingness all around you when flying at speeds close to 950 kph (570 mph).  Unlike having a concrete wall just a few feet away from a train traveling at high speeds.

High-speed rail may work in France and Japan.  The only two rail lines to pay for themselves are in these countries.  But every other passenger rail line in the world needs a government subsidy.  Because the costs of a rail infrastructure are just so great.  Making high-speed rail more of a source of union jobs than an efficient means of transportation.  Which is why they are a fixture in countries with liberal governments.  Who subsidize the high cost of these union jobs with taxpayer money.  In exchange for votes in the next election.


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Vacuum Toilet

Posted by PITHOCRATES - April 24th, 2013

Technology 101

The Siphon in a Flush Toilet sucks the Waste out of the Toilet Bowl

The common flush toilet in our homes is located in a bathroom.  A dedicated room in our houses.  Often times tucked away off of a bedroom.  Private and secure.  Where we can take care of any of our business with comfort and dignity.  It’s nice.  Hiding that part of our life away from the rest of the world.  In fact, some people are such nervous pooers that they can’t go anywhere but at home.  Lucky for them they didn’t live in ancient Rome where communal toilets were long benches with holes in them.  And people sat next to each other while doing their business.  Elbow to elbow.  Literally.

What makes the flush toilet in our homes possible is basically one thing.  They don’t move.  They’re permanent installations that sit on terra firma.  And because of that they can use gravity.  When we flush a toilet water pours down from a tank into a bowl.  Forcing the contents of the bowl up and over the drain out of the bowl.  The siphon.  Filling this pipe completely with water.  So that when the water falls down into the sanitary sewer pipe it creates a siphon.  Pulling everything behind it down into the sanitary drain.  Where gravity pulls it down to pipes under our houses and into the sanitary sewer system under the street in front of our house.  Where these pipes slope downhill towards the wastewater treatment plant.

The flush toilet works in our house because they don’t move.  And we can dig pipes deep underground.  Two things we can’t do on boats, trains and planes.  So early boats and trains had a simple toilet.  If you looked down into the toilet seat on a boat you saw the water.  And if you looked down into the toilet seat on a train you saw the railroad track underneath.  Which could really chill a pair of butt cheeks on a crisp winter day.  Making a cold toilet seat in your bathroom in the morning seem toasty warm by comparison.  Early planes had a chemical toilet.  Basically a port-a-potty.  Filling the air with the aroma of a construction site toilet.

The Suction of a Vacuum Toilet is greater than the Siphon of a Flush Toilet

Today in most countries you can’t defecate into a river, lake or ocean.  Or onto railroad tracks.  It’s not sanitary.  And just plain disgusting.  But because boats, trains and planes move a flush toilet with a bowl full of water just isn’t an option.  Because water in a moving bowl tends to splash out of the bowl.  Which can splash corrosive waste in nooks and crannies around the toilet.  Making a mess in the lavatory.  Though chemical toilets were an option and we used them for some time they just didn’t smell good.  Especially on an airplane.  As you just couldn’t roll the window down for some fresh air.

A flush toilet on an airplane has another problem.  Water has mass.  To carry water for flush toilets increases the weight of the airplane.  Requiring more fuel.  As fuel is the greatest cost of flying airlines and aircraft manufacturers do everything within their power to reduce the weight of an airplane.  Which is why today’s aircraft use a vacuum toilet system.  Where instead of using water and gravity to create a siphon they use a vacuum pump to create a suction.  A vacuum toilet does not use water.  There is no water in the bowl.  When you ‘flush’ a drain opens in the bottom of the bowl and a powerful vacuum sucks it clean.

The suction of a vacuum toilet is greater than the siphon of a flush toilet.  Allowing smaller pipes as the powerful suction does not allow any clogging of pipes.  Smaller pipes (and no water like in a flush toilet) reduce weight.  Helping to cut the cost of flying.  That powerful suction also sucks out all of the stink with each flush.  Another benefit of the vacuum toilet.  Which is a good thing in a small room without a window you can open.

A Truck transfers the Sanitary Waste from an Aircraft Holding Tank into the Sanitary Sewer System

Planes pitch up, pitch down and bank left and right.  Which would be a problem for wastewater moving under the force of gravity.  Or for water in a bowl.  Which is another benefit of a vacuum toilet system.  Which doesn’t use gravity.  Or water.  So the pipes of a vacuum toilet system can run in any direction.  Up, down or flat and level.  The force of the suction will pull the waste to the holding tank no matter the path it takes to the holding tank.

As the flight progresses people use the toilets.  And the holding tanks fill up with waste.  When they land they are pretty full.  And the airlines need to empty them.  If you ever watched an airplane at a gate after it lands you will see a whirlwind of activity.  Baggage and freight comes off.  Then they load baggage and freight for the next flight.  Cleaning crews enter the aircraft.  Food service cleans out the galleys and loads food and beverages for the next flight.  Fuel trucks refuel the aircraft (either from a fuel truck or a fuel hydrant system in the apron).  And then there’s the poop truck.  Which will open a hatch on the belly of the aircraft.  Connect a large hose.  Open a valve.  And drain the holding tank into the truck.  Pump in some blue disinfectant.  And make the toilets ready for the next flight.

The poop truck then drives someplace where they can dump their load.  Larger airports may have a special building for this.  Where they drive in and stop over a grate in the floor.  Dump their load onto the grate.  Water sprays onto the floor to help wash everything into and through the grate.  Where it falls into a ‘chopper’ pump to break down the solids more.  And then it enters the sanitary sewer system at the airport.  Where it uses gravity to flow downhill towards a wastewater treatment plant.  Just like it does when we use the bathroom in the privacy and security of our home.


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Boeing 787 Dreamliner, Fuel Costs, Electric Systems, Auxiliary Power Unit and Lithium-Ion Batteries

Posted by PITHOCRATES - January 23rd, 2013

Technology 101

Auxiliary Devices reduce the Power Output of the Engine available to Drive a Car Forward

If you’re middle age (or old) you may remember looking under the hood of a car.  When you could see things.  In the days of rear-wheel drive cars and big engines.  The front of the engine had a power takeoff pulley attached to the crank shaft.  The thing the pistons spun when it converted reciprocal motion into rotational motion.  Wrapped around that pulley were a lot of belts.  Sometimes three or more.  They transferred the rotational motion of the crankshaft to auxiliary devices.

These devices included the water pump that pumped engine coolant to remove the heat of combustion.  An alternator to generate electric power.  A power steering pump to make steering easier.  An air pump to inject air into the exhaust system to help complete the combustion process to reduce emissions.  (An electronic air pump has since replaced this belt-driven device.)  And an air conditioner compressor.  All of these devices reduce the power output of the engine available to drive the car forward.  Requiring more fuel.

Today’s cars have a lot more stuff under the hood.  Engines are often mounted transversely.  And the multiple belts have been replaced with one serpentine belt that winds around all of these auxiliary devices.  And engines are smaller.  With on board computers that maximize the power output of smaller engines.  That drive lighter cars.  But one thing hasn’t changed.  When you turn on the air conditioning you can still hear the engine labor under the additional load.  While burning more fuel.

The Boeing 787 Dreamliner can do what other Planes can do while Burning less Fuel

In the airline industry the greatest cost is fuel.  So anything that allows airlines to burn less fuel greatly interests the airlines.  And it’s why pilots do careful calculations to determine how much fuel to carry.  That is, to determine the absolute minimum amount of fuel to carry.  If it were up to pilots they’d top off the fuel tanks.  But if they did that the airlines could not operate profitably.  Because you have to burn fuel to carry fuel.  And the more fuel you carry the more you have to burn.  Increasing your fuel costs to the point an airline loses money.  Especially if you’re landing with a lot of fuel in your tanks.  So pilots load less fuel than they would want.  Because to get a paycheck their company has to operate at a profit.  But it doesn’t stop there.  Not for aircraft designers.

Designers have been using more plastic in airplanes.  Because plastic is lighter than metal.  So engines can burn less fuel.  These composite materials are also stronger than metal.  So less of them can replace equivalent metal components.  So engines can burn less fuel.  Airlines have also been charging more for carry-on luggage.  In part to help offset their rising fuel costs.  And in part to encourage people to carry less onto the airplane.  So engines can burn less fuel.  Then Boeing raised the bar on burning less fuel.

The Boeing 787 Dreamliner is a remarkable design.  Remarkable because it delivers what airlines want most.  An airplane that can do what other planes can do.  But does it while burning less fuel.  Boeing has used more composite material than any other manufacturer.  Making the 787 the lightest in its class.  And lighter things allow engines to burn less fuel.  But Boeing did more than just make the airplane lighter.  They used electric systems to replace hydraulic and pneumatic systems normally found on an airplane.

The 787 Dreamliner uses Lithium-Ion Batteries to start their Auxiliary Power Unit

Hydraulic and pneumatic systems bleed power from the aircraft engines.  As the engines drive pumps and compressors for these systems.  By converting these to electric systems more of the power of the engines goes to producing thrust.  Which means they burn less fuel to fly to their destination.  They even replaced the pneumatic starters (that spin the engines during starting) with a combination electric starter/generator.  Saving weight.  And reducing the complexity.  By replacing two parts (pneumatic starter and electric generator) with one (combination starter/generator).

To start the aircraft engines they first start the auxiliary power unit (APU).  The APU is typically mounted near the tail of the aircraft.  The APU provides power, lights, heating, air conditioning, etc., when the main engines aren’t running.  Some provide back up power (electric and pneumatic) should the main engines fail in flight.  The APU also drives an air compressor to provide the pneumatic power to spin the main engines for starting.  Going to all electric systems (except for the engine anti-ice system) removes the air compressor from the APU.  Reducing the weight.  And they further reduced the weight by making another change.  To the battery that starts the APU.

The 787 uses lithium-ion batteries.  Which can provide the same power larger batteries of different technologies can provide.  As lithium-ion batteries has a very high energy density.  But with great energy density comes great heat.  Some of these batteries have actually caught fire.  In electric cars.  Laptop computers.  Cell phones.  Even in Boeing 787 Dreamliners.  They’re not sure why.  And they’ve grounded the fleet until they figure out why.  It may be because they are overcharging.  Or that there are internal shorts causing a thermal runaway (releasing all the stored energy at one time).  Or the caustic electrolyte is leaking and causing a fire.  Until they determine what the problem is the 787 will remain grounded.  Making it very difficult to enjoy the cost savings of that remarkable design.


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Thrust, Drag, Lift, Weight, Concorde, Center of Pressure, Center of Gravity, Boeing 747, Slats and Flaps

Posted by PITHOCRATES - January 16th, 2013

Technology 101

The Drawback to increasing Thrust and Lift with more Powerful Engines is the Weight of Greater Fuel Loads

To get an airplane off of the ground requires two things.  To produce thrust that is greater than drag.  And to produce lift that is greater than weight.  You do this and you’ll get any airplane off of the ground.  Of course, getting these two things is not the easiest thing to do.  Primarily because of the purpose of airplanes.  To move people and freight.  People and freight add weight.  Which increases the amount of lift needed.  And they make the plane bigger.  A bigger object displaces more air increasing drag.  And thus requiring more thrust.

Engines provide thrust.  And wings provide lift.  So the obvious solution to overcome greater drag is to produce greater thrust.  And the solution to overcome greater weight is to produce greater lift.  And we do both with fuel.  Greater amounts of fuel can power bigger engines that can produce more thrust.  And larger wings can produce greater lift.  But larger wings also produce more drag.  Requiring additional thrust.  And fuel.  Or, we can produce greater lift by moving air over the wings faster.  Also requiring additional thrust.  And fuel.

Of course, the obvious drawback to increasing both thrust and lift is the added weight of the fuel.  The more fuel carried the more weight lift has to overcome.  Requiring more powerful engines.  Or bigger wings.  Both of which require more fuel.  This is why our first planes were small by today’s standards.  The thrust of a propeller engine could not produce enough thrust to travel at high speeds.  Or operate at high altitudes.  And the first wings were relatively fixed.  Having the same surface area to produce lift at takeoffs and landings.  As well as at cruising altitudes.  Big wings that allowed the lifting of heavier weights produced a lot of drag.  Requiring more fuel to overcome that drag.  And the added weight of that fuel limited the number of people and freight they could carry.  Or they could trade off that fuel for more revenue weight.  The smaller fuel load, of course, reduced flying times.  Requiring an additional takeoff and landing or two to refuel.

A Wing that produces sufficient Lift at 600 MPH does not produce sufficient Lift at Takeoff and Landing Speeds

The supersonic Concorde was basically a flying gas can.  It was more missile than plane.  To travel at those great speeds required a very small cross section to reduce drag.  Limiting the Concorde to about 100 revenue paying passengers.  Its delta wing performed well at supersonic flight but required a drooping nose so the pilot could see over it to land and takeoff due to the extreme nose pitched up attitude.  As Concorde approached supersonic speeds the center of pressure moved aft.  Placing the center of gravity forward of the center of pressure.  Causing the nose to pitch down.  You correct this with trim controls on slower flying aircraft.  But using this on Concorde would create additional drag.  So they trimmed Concorde by pumping the remaining fuel to other fuel tanks to move the center of gravity to the center of pressure.

They designed Concorde to fly fast.  Which came at a cost.  They can only carry 100 revenue paying passengers.  So they can only divide the fuel cost between those 100 passengers.  Whereas a Boeing 747 could seat anywhere around 500 passengers.  Which meant you could charge less per passenger ticket while still earning more revenue than on Concorde.  Which is why the Boeing 747 ruled the skies for decades.  While Concorde flies no more.  And the only serious competition for the Boeing 747 is the Airbus A380.  Which can carry even more revenue paying passengers.  How do they do this?  To fly greater amount of people and freight than both piston-engine and supersonic aircraft?  While being more profitable than both?  By making compromises between thrust and drag.  And lift and weight.

Jet engines can produce more thrust than piston engines.  And can operate at higher altitudes.  Allowing aircraft to take advantage of thinner air to produce less drag.  Achieving speeds approaching 600 mph.  Not Concorde speeds.  But faster than every other mode of travel.  To travel at those speeds, though, requires a cleaner wing.  Something closer to Concorde than, say, a DC-3.  Something thinner and flatter than earlier wings.  But a wing that produces lift at 600 mph does not produce enough lift at takeoff and landing speeds.

Planes need more Runway on Hot and Humid Days than they do on Cool and Dry Days

The other big development in air travel (the first being the jet engine) are wings that can change shape.  Wings you can configure to have more surface area and a greater curve for low-speed flying (greater lift but greater drag).  And configure to have less surface area and a lesser curve for high-speed flying (less lift but less drag).  We do this with leading-edge slats (wing extensions at the leading edge of the wing).  And trailing-edge flaps (wing extensions at the trailing edge of the wing).  When fully extended they increase the surface area of the wing.  And add curvature at the leading and trailing edge of the wing.  Creating the maximum amount of lift.  As well as the greatest amount of drag.  Allowing a wing to produce sufficient lift at takeoff speeds (about 200 mph).  Once airborne the plane continues to increase its speed.  As it does they retract the slats and flaps.  As the wing can produce sufficient lift at higher speeds without the slats and flaps extended.

But there are limits to what powerful jet engines and slats/flaps can do.  A wing produces lift by having a high pressure under the wing pushing up.  And a low pressure on top of the wing pulling it up.  The amount of air passing over/under the wing determines the amount of lift.  As does the density of that air.  The more dense the air the more lift.  The thinner the air the less lift.  Which is why planes need less runway on a cold winter’s day than on a hot and humid summer’s day.  If you watch a weather report you’ll notice that clear days are associated with a high pressure.  And storms are associated with a low pressure.  When a storm approaches meteorologists will note the barometer is falling.  Meaning the air is getting thinner.  When the air is thinner there are fewer air molecules to pass over the wing surface.  Which is why planes need more runway on hot and humid days.  To travel faster to produce the same amount of lift they can get at slower speeds on days cooler and dryer.

For the same reason planes taking off at higher elevations need more runway than they do at lower elevations.  Either that or they will have to reduce takeoff weight.  They don’t throw people or their baggage off of the airplane.  They just reduce the fuel load.  Of course, by reducing the fuel load a plane will not be able to reach its destination without landing and refueling.  Increasing costs (airport and fuel expenses for an additional takeoff and landing).  And increasing flying time.  Which hurts the economics of flying a plane like a Boeing 747.  A plane that can transport a lot of people over great distances at a low per-person cost.  Adding an additional takeoff and landing for refueling adds a lot of cost.  Reducing the profitability of that flight.  Not as bad as a normal Concorde flight.  But not as good as a normal Boeing 747 flight.


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Air, Low Pressure, High Pressure, Lateen Sail, Flight, Wing, Lift, Drag, Leading Edge Slats, Trailing Edge Flaps and Angle of Attack

Posted by PITHOCRATES - October 10th, 2012

Technology 101

There’s more to Air than Meets the Eye even though it’s Invisible

When you take a shower have you noticed how the shower curtain pulls in towards you?  Have you ever wondered why it does this?  Here’s why.  Air has mass.  The water from the showerhead sends out a stream of water drops that also has mass.  So they fall to the floor of the shower.  Pushing air with it.  And pulling air behind it.  (Like drinking through a straw.  As you suck liquid out of the straw more liquid enters the straw.)  So you not only have a stream of water moving down alongside the shower curtain.  You also have a stream of air moving down alongside the shower curtain.

As the falling water sweeps away the air from the inside of the shower current it creates a low pressure there.  While on the outside of the curtain there is no moving water or air.  And, therefore, no change in air pressure.  But there is a higher pressure relative to the lower pressure on the inside of the shower curtain.  The low pressure inside pulls the curtain while the high pressure outside pushes it.  Causing the shower curtain to move towards you.

There’s more to air than meets the eye.  Even though it’s invisible.  It’s why we build modern cars aerodynamically to slice through large masses of invisible air that push back against cars trying to drive through it.  Making our engines work harder.  Consuming more gas.  And reducing our gas mileage.  While race cars will use spoilers to redirect that air up, forcing the weight of the car down on the tires.  To help the tires grip the road at higher speeds.  We even design skyscrapers to be aerodynamic.  To split the prevailing winds around the buildings to prevent large masses of air from slamming into the sides of buildings, minimizing the amount buildings sway back and forth.

We put the Engines on, and the Fuel in, the Wings to Counteract the Lifting Force on an Aircraft’s Wings

Air can be annoying.  Such as when the shower curtain sticks to your leg.  As it steals miles per gallon from your car.  When it shakes the building you’re in.  But it can also be beneficial.  As in early ship propulsion before the steam engine.  Large square-rigged sails that pushed ships along the prevailing winds.  And triangular lateen sails that allowed us to travel into the wind.  By zigzagging across the wind.  With the front edge of a lateen sail slicing into the wind.  The sail redirects the wind on one side of the sail to the rear of the boat that pushes the boat forward.  While the wind on the other side follows the curved sail creating a low pressure that pulls the boat forward.  Like the inside of that shower curtain.  Only with a lot more pulling force.

Harnessing the energy in wind let the world become a smaller place.  As people could travel anywhere in the world.  Of course, some of that early travel could take months.  And spending months on the open sea could be very trying.  And dangerous.  A lot of early ships were lost in storms.  Ran aground on some uncharted shoal.  Or simply got lost and ran out of drinking water and food.  Or fell to pirates.  So it took a hearty breed to travel the open seas under sail.  Of course today long-distant travel is a bit easier.  Because of another use for air.  Flight.

Like a lateen sail an aircraft wing splits the airflow above and below the wing.  And like the lateen sail an aircraft wing is curved.  The air pushes on the bottom of the wing creating a high pressure.  While the air passing over the curve of the top of the wing creates a low pressure.  Pulling the wing up.  In fact, it’s the wind passing over the top of the wing that does the lion’s share of lifting airplanes into the air.  The low pressure on top of the wing is so great that they put the engines on the wings, and the fuel in the wings, to counteract this lifting force.  To prevent the wings from curling up and snapping off of the plane.  Planes with tail-mounted engines have extra reinforcement in the wings to resist this bending force.  So those lifting forces only lift the plane.  And not curl the wing up until it separates from the plane.

To make Flying Safe at Slow Speeds they add Leading Edge Slats and Trailing Edge Flaps to the Wing

Sails can propel a ship because a ship floats on water.  The wind only propels a ship forward.  On an airplane the wind moving over the wings provides only lift.  It does not propel a plane forward.  Engines propel planes forward.  And it takes a certain amount of forward speed to make the air passing over the wings fast enough to create lift.  The faster the forward air speed the greater the lift.  Today jet engines let planes fly high and fast.  In the thin air where there is less drag.  That is, where the air has less mass pushing against the forward progress of the plane.  At these altitudes the big planes cruise in excess of 600 miles per hour.  Where these planes fly at their most fuel efficient.  But these big planes can’t land or take off at speeds in excess of 600 miles per hour.  In fact, a typical take-off speed for a 747-400 is about 180 miles per hour.  Give or take depending on winds and aircraft weight.  So how does a plane land and take off at speeds under 200 mph while cruising at speeds in excess of 600 mph?  By changing the shape of the wing.

We determine the amount of lift by the curvature and surface area of the wing.  The greater the curvature the greater the lift.  However, the greater the curvature the greater the drag.  And the greater the drag the more fuel consumed at higher speeds.  And the more stresses placed on the wing.  Also, current runways are about 2 miles long for the big planes.  That’s when they land and take off at speeds under 200 mph.  To land and take off at speeds around 600 mph would require much longer runways.  Which would be extremely costly.  And dangerous.  For anything traveling close to 600 mph on or near the ground would have a very small margin of error.  So to make flying safe and efficient they add leading edge slats to the front edge of the wing.  And trailing edge flaps to the back edge of the wing.  During cruise speeds both are fully retracted to reduce the curvature of the wing.  Allowing higher speeds.  At slower speeds they extend the slats and flaps.  Greatly increasing the curvature of the wing.  And the surface area.  Providing up to 80% more lift at these slower speeds.

At takeoff and landing pilots elevate the nose of the aircraft to increase the angle of attack of the wing.  Forcing more air under the wing to push the wing up.  And causing the air on top of the wing to turn farther away for its original direction of travel as it travels across the top of the up-tilted wing.  Creating greater lift.  And the ability to fly at slower speeds.  However, if the angle of attack it too great the smooth flow of air across the wing will break away from the wing surface and become turbulent.  The wing will not be able to produce lift.  So the wing will stall.  And the plane will fall out of the sky.  With the only thing that can save it being altitude.  For in a stall the aircraft will automatically push the stick forward to lower the nose.  To decrease the angle of attack of the wing.  Decrease drag.  And increase air speed.  If there is enough altitude, and the plane has a chance to increase speed enough to produce lift again, the pilot should be able to recover from the stall.  And most do.  Because most pilots are that good.  And aircraft designs are that good.  For although flying is the most complicated mode of travel it is also the safest mode of travel.  Where they make going from zero to 600 mph in a matter of minutes as routine as commuting to work.  Only safer.


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