Beam, Fulcrum, Torque, Law of the Lever and Mechanical Advantage

Posted by PITHOCRATES - April 30th, 2014

Technology 101

(Originally published May 1st, 2013)

A Lever is a Rigid Beam on a Fulcrum

Archimedes said, “Give me a place to stand, and I shall move the Earth with it.”  At least we think he did.  Archimedes of Syracuse was a Greek genius.  Mathematician.  Physicist.  Engineer.  Inventor.  And astronomer.  One of many of the ancient Greeks who advanced modern civilization.  By using math and science.  He did a lot.  And explained why things worked the way they did using math.  Like the Law of the Lever.

In the days before the twist-off bottle cap we used bottle openers.  Because try as we might we could not pry a bottle cap off with our hands.  Most grown men just didn’t have the strength to do that.  But a child could open a bottle if that child used a bottle opener.  For that bottle opener is a lever.  Giving the child leverage.  The ability to use a little bit of force to do a lot of work.

A lever is a rigid beam on a fulcrum.  Like a seesaw.  A common playground fixture.  If two kids of equal weight are on either end of the seesaw and the fulcrum is in the center these kids can effortless push up and down.  But if a grown adult sits on one end and a child is on the other the weight of the adult will drop his side of the seesaw down.  Leaving the child up in the air on the other side.

As the Lever increases in Length the more it will Amplify the Input Force we Apply

Now that’s no fun.  Having the seesaw permanently tipped in one direction.  However, even two people of different weights can enjoy playing on the seesaw.  All they have to do is move the fulcrum towards the heavier person until the seesaw balances.  So that there is a short length of seesaw between the fulcrum and the heavy person.  And longer length of seesaw between the fulcrum and the lighter person.  This creates the same amount of torque on both side of the fulcrum.

Torque is the turning force created by a force acting about a fulcrum.  The force in this case is the weight of the people on the seesaw.  Which we calculate by multiplying their mass by the force of gravity.  With the force of gravity being constant the greater the mass the greater the weight.  This weight pressing down on the beam creates torque.   And the further away from the fulcrum the greater the turning force.  Such that a lighter weight at a greater distance from the fulcrum can balance a greater weight at a shorter distance from the fulcrum.  Allowing a child to play on a seesaw with someone of far greater mass.  Because the lever amplified the smaller force of the child.  Allowing the child to move a heavier weight.  To illustrate this consider the following table.

Lever

This is just a visual aid.  The numbers don’t represent anything.  It just shows a relationship between force and the length of the lever.  In this example we need 1000 units of force to move something.  If we use a lever that is 10 units from the fulcrum we need to apply 100 units of force.  If we have a lever that is 40 units from the fulcrum we only need to apply 25 units of force.  If we have a lever that is 80 units from the fulcrum we only need to apply 12.5 units of force.  As the lever increases in length the more it will amplify the input force we apply.  Which is why a child can open a bottle with a bottle opener.

A Wheelbarrel combines the Lever with the Wheel and Axle

A lever gives us mechanical advantage.  The amplification of a small input force into a larger output force.  Such as a hand-held bottle opener.  But what about the kind that used to be fastened to pop machines?  When you bought a glass bottle of pop out of a vending machine?  The fulcrum is the fixed bottle opener.  And the lever is the bottle.  A can opener was often on the other end of a bottle opener.  Instead of a grip to latch onto a bottle cap this end had a triangular knife.  When we lifted up on the lever it pressed down and pierced a hole in a can.

A wheelbarrel allows us to move heavy loads.  This device combines two simple machines.  A wheel and axle.  And a lever.  The wheel and axle is the fulcrum.  The lever runs from the fulcrum to the handles of the wheelbarrel.  We place the load on the lever just before the axle.  When we lift the far end of the lever we can tilt up the load and balance it over the axle.  The lever amplifies the force we apply.  And the wheel and axle reduce the friction between this load and the ground.  Allowing us to move a heavy load with little effort.

Today’s pop bottles have screw-top caps.  Some people still use a lever to help open them, though.  A pair of pliers.  We use the pliers because we don’t have the strength to grip the cap tight enough to twist it open.  The pliers are actually two levers connected together at the fulcrum.  The pliers amplify our hand strand-strength to get a very secure grip on the bottle cap.  While our hands compress the two levers together getting a firm grip on the cap we can then use our arm to apply a force on the handles of the pliers.  Providing a torque to turn the bottle cap.  Very simple machines that make everyday life easier.  Thanks to the knowledge Archimedes handed down to us.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , ,

Helicopter

Posted by PITHOCRATES - January 15th, 2014

Technology 101

Varying the Pitch of the Tail Rotor Blade counters the Twisting Force caused by the Helicopter Engine

If you have a rear-wheel drive car with a longitudinally mounted engine (the crankshaft in the engine runs from front to back) you’ve probably noticed the car twisting along the longitudinal axis when starting or revving the engine.  If you ever operated a hand-drill and had the drill bit get stuck in the material you’re drilling through you’ve probably felt the drill twist in your hands.  These are examples of torque.  As the engine or drill motor spins in one direction they also create a counter torque in the opposite direction.  If a drill bit spins clockwise the motor is trying to spin counterclockwise.  Around the axis of the drill bit.

A helicopter has an engine spinning in one direction.  This spins the rotor that creates lift and directional motion.  But a helicopter is not attached to anything.  Motor mounts hold an engine in place in a car that prevents it from spinning in the opposite direction of the crankshaft.  With the car in contact with the ground.  We hold a drill motor to prevent it from spinning in the opposite direction of the drill bit.  With ourselves in contact with the ground.  A helicopter hovers over the ground, though.  It has no physical attachment to prevent the counter torque from spinning the helicopter in the opposite direction from the rotor.  Which is why there is a tail rotor on a helicopter.

Running out from behind the engine/cockpit of a helicopter is a tail boom.  At the end of that boom is a small rotary wing that spins like a propeller.  We can vary the pitch of this blade to push air through in either direction.  Or move it to a neutral position and move no air through it.  By varying the pitch of the tail rotor blade we can provide a counter force to balance the twisting force caused by the engine.  This is what we do with the foot pedals in the helicopter.  Change the pitch in the tail rotor blade to apply more or less counter-twisting force.  To cancel that created by the engine.  And to turn the helicopter to face a new direction.  Especially when hovering.  Helicopters with two large lift-producing rotors/engines (like a Boeing CH-47 Chinook) don’t need tail rotors.  The two engines just spin in opposite directions.  And cancel each other’s twisting torque.

On a Helicopter they Twist the Rotor Blade to Produce more Lift and Increase the Angle of Attack

Both planes and helicopters produce lift with a wing.  A fixed wing on an airplane.  And a rotary wing on a helicopter.  Air passing over the curved surfaces of a wing produces lift.  The more curved the wing the more lift.  And the greater the angle of attack of the wing the greater the lift.  Which is why planes take off with the nose/wings pitched up to create the maximum amount of lift.

Powerful engines on airplanes produce thrust to move the wing through the air.  Requiring long runways to take off.  And dangerous high speeds on the ground.  About 100 mph or so to get airborne.  Making the take off the most dangerous part of flying.  A helicopter, on the other hand, needs no runway.  For it can take off and land vertically.  Because the engine spins the wing through the air to create lift.  It doesn’t have to accelerate the helicopter to produce lift.

Airplane wings have leading-edge slats and trailing edge flaps to increase the curvature of the wing.  And a tail-mounted elevator that can deflect air up pushing the tail down, pitching the nose and wings up.  Increasing the angle of attack of the wings.  On a helicopter they twist the rotor blade to produce more curvature and increase the angle of attack.  With something called the swash plate assembly.

If you let go of the Controls of a Helicopter it will likely Crash for a Helicopter is Inherently Unstable

The rotor shaft rises up vertically from the engine and terminates in the rotor blade assembly above the helicopter.  And passes through the swash plate assembly.  A fixed lower swash plate that doesn’t spin.  And an upper swash plate that spins with the rotor.  Sandwiched between the swash plates are ball bearings.  Allowing these two plates to be in physical contact with each other.  Yet allows the top plate to spin while the bottom plate remains stationary.

Attached between the upper swash plate and the rotor blades are control rods.  Attached between the lower swash plate and the helicopter control levers in the pilot’s hands are control rods.  It is via the swash plate assembly that the pilot’s control inputs are transferred to the rotor blades.  When the pilot pushes the swash plate assembly up with the collective control in his or her left hand (looks like a parking brake on a car) the control rods on the upper plate push up on one side of each rotor blade equally.  Increasing its angle of attack and curvature of each blade equally.  Creating lift.  And drag.  Causing the engine to slow down from the increased load on it.  So when the pilot lifts the collective he or she also twists the handle to increase engine speed (like the accelerator on a motorcycle).

The pilot’s right hand controls the cyclic.  Or the stick coming up between his or her knees.  This is what gives a helicopter its directional motion.  When the pilot moves the cyclic forward it tips the swash plate assembly forward.  The back side of the swash plate assembly rises up while the front side remains roughly where it was.  So as a rotor blade rotates from the front position (forward of the cockpit) to the back position (behind the cockpit) the control rod begins to push up the leading edge of the blade.  Increasing its angle of attack and the curvature of the blade.  Reaching its highest position at the very back of its rotation.  Producing its maximum lift.  As it travels from the back to the front the control rod begins to lower the leading edge of the blade.  Decreasing its angle of attack and the curvature of the blade.  Reaching its lowest position at the very front of its rotation.  This uneven lifting force of the rotor blade tips the helicopter forward and pulls it forward in directional motion.  If the pilot tips the cyclic to the left lift increases on the right side of the rotor, pulling the helicopter to the left.  If the pilot pulls back on the cyclic the lift increases on the front of the rotor, pulling the helicopter backward.

Planes are inherently stable.  If you let go of the controls it will fly true and straight.  For awhile at least.  If you let go of the controls of a helicopter it will likely crash.  For a helicopter is inherently unstable.  And requires constant inputs to the flight controls from the pilot to maintain stable flight.  As it is a delicate balancing act between the collective, the cyclic and the foot pedals.  For every input of one creates an imbalance that must be corrected by the input of another.  Making the helicopter pilot perhaps the most skilled of all pilots.  Especially those kids just out of high school who flew in Vietnam.  Who flew these complicated flying machines like sports cars as they avoided enemy fire.  Making them without a doubt the finest pilots ever to fly.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , ,

A Diesel Car is a better value than an Electric Car

Posted by PITHOCRATES - December 22nd, 2013

Week in Review

People aren’t buying electric cars.  Because they are too expensive.  And because of their limited range.  Governments (federal and states) are trying to encourage people to buy cars they don’t want by offering subsidies to both manufacturers and buyers.  Which is getting some people to buy these cars.  But not many.  For even with those subsidies they’re still expensive.  And still have limited range.  Unlike these alternative cars (see These Diesels From Audi, BMW and Mercedes Cost Less To Own Than Your Gas-Powered Luxury Car by Hannah Elliott posted 12/19/2013 on Forbes).

Automakers have long lamented the American public’s reticence to embrace diesel technology as wholeheartedly as have Europeans…

But those who have adopted diesel love it. Audi head Scott Keogh routinely tells me his company sells out of each TDI model they make; Detlev von Platen at Porsche  told me at the LA auto showst month that diesel technology will continue to play an “increasingly significant” role for its fleet, especially the best-selling Panamera.

The truth is that while there is a price premium (roughly $5,300 on average) associated with the initial purchase cost of diesel vehicles, they typically get 30% better gas mileage and flaunt superior torque numbers and reliability ratings. The automotive analysis firm Vincentric estimates that driving a diesel car will save $2,117 in fuel costs over one year assuming annual rate of 15,000 miles.

Note the one thing conspicuous by its absence.  The word ‘subsidies’.  For people will pay a premium for a diesel.  Because there is value in a diesel.  They have superior torque.  Giving them greater pulling force than comparable sized gasoline-powered cars.  Better reliability.  And best of all they get a 30% better fuel mileage.  Which gives them greater range than a gasoline-powered care with a comparable sized fuel tank.  Giving them a greater range between fuel-ups than with a gasoline car.  And a far, far, far, far, far greater range than an electric car.  Giving the diesel an excellent value for the money.  Something you don’t have to bribe people to buy with subsidies.

www.PITHOCRATES.com

Share

Tags: , , , , , , ,

Wheel and Axle

Posted by PITHOCRATES - May 8th, 2013

Technology 101

The Key to the Wheel and Axle is the different Angular Velocities of the Outer Surfaces of the Axle and Wheel

Have you ever tried to turn a screw using only your fingers?  You might be able to get it started and spin it a few rotations.  But eventually you’ll be unable to turn the screw any further.  If you use a screw driver, though, you’ll be able to turn the screw all the way in.  Why?  For the same reason you can turn the handle on the spigot when you want to water the grass.  And why you can open the door when you enter your home.  Because of a wheel and axle.

The wheel and axle is one of six simple machines.  The others being the lever, the inclined plane, the pulley, the wedge and the screw.  The wheel and axle are two circular parts whose outer surfaces rotate at different speeds.  Think of a large wagon wheel.  Wooden spokes connect the outer rim of the wheel (the felloes) to the hub.  Imagine the wheel turning one quarter turn.  The end of the spoke at the felloes has to cover more distance than the end of the spoke at the hub.  Therefore the spoke end at the felloes travels faster than the spoke end at the hub.

In the ideal machine power in equals power out.  And power equals the torque (twisting force) multiplied by the angular velocity (how fast something spins around).  The key to the wheel and axle is the different angular velocities of the outer surfaces of the axle and wheel.  If power remains the same while the angular velocity changes then the torque must change.  Let’s use some meaningless numbers to illustrate this point.  The angular velocity is 4 and the torque is 2 on a wheel’s surface and the angular velocity is 2 and the torque is 4 on an axle.  Power in equals 8 while power out also equals 8.  But the torque increases.  So using the wheel and axle gives us mechanical advantage.  The ability to amplify force to do useful work for us.

Mechanical Advantage amplifies our Input Force to do Useful Work for Us

What makes a screwdriver work is the handle on it that we grip.  Which represents the outer surface of the wheel.  While the metal shaft the handle fastens to is the axle.  The handle provides a larger surface for our hand to grip.  Allowing us to apply a greater turning force (torque) to the handle than we could to the metal shaft.  The angular velocity of the surface of the handle is greater than the metal shaft.  So the torque of the metal shaft is greater than the torque we apply to the handle of the screwdriver.

The mechanical advantage amplifies our input force to do useful work for us.  To turn a screw that our fingers aren’t strong enough to turn.  Just as the handle on the water spigot allows us to twist it open.  And the door knob allows us to twist open the latching mechanism to open a door.  Things we couldn’t do without a large handle to grasp and twist.  To amplify our limited force.  To do useful work.

The old-fashioned water well is another example.  Across the top of the well is an axle.  A length of rope long enough to reach the water below is attached to a bucket.  The other end is attached to the axle.  Also attached to the axle is a wheel that we can turn by hand.  Or a hand crank.  As we turn the wheel or crank the rope wraps around the axle.  Pulling up the bucket full of water.  The speed of our hand spinning the wheel or the crank is greater than the speed of the spinning axle.  That is, our input angular velocity is reduced.  Which increases the torque on the axle.  Allowing it to pull up a heavy bucket of water that we couldn’t do as easily without the wheel and axle.

Using more Gears in a Gear Train can greatly Reduce the Angular Velocity which Greatly Increases the Output Force

We can amplify our input force more by adding some additional wheels.  And some gears.  For example, when we started harvesting sugarcane we used a mechanical press to squeeze the juice out of the cane.  And we did this by running the sugarcane through a couple of rollers with a narrow gap between them.  Crushing and pulling this cane through these rollers, though, required a lot of force.  Which we produced with a couple of wheels and axles.  One axle was the roller.  Attached to this axle was a large wheel.  Only we didn’t turn this wheel.  This wheel was a large gear.  Its teeth meshed with the teeth of a smaller gear on another axle.  Attached to this second axle was another wheel.  With a hand crank attached to it.

When we turned this wheel we rotated the small gear on the hand-crank axle.  This gear turned the larger gear attached to the roller axle.   Which pulled and crushed the cane through the press.  This reduced the angular velocity twice.  Thus increasing the torque twice.  Which twice amplified our input force.  Using more gears in a gear train can greatly reduce the angular velocity from the input axle to the output axle.  Greatly increasing the output force.  Like in a motor vehicle.  The engine spins at a high angular velocity.  The power output of the engine spins a gear train inside a transmission.  Greatly reducing the output angular velocity.  While greatly increasing the turning force sent to the drive wheels.

High-spinning electric motors have replaced the hand-crank on modern sugarcane presses.  These use a gear train or a belt and pulley system (or both) to reduce the spinning speed of the electric motor.  So when the force turns the rollers it doesn’t pull the cane through dangerously fast.  It pulls it through slow but with great force.  Which will flatten the cane and squeeze every last drop of fluid from it.  Or someone’s hand if it gets caught in the rollers.  Which usually have hand-guards around them to prevent that from happening.  But some people still operate machines that have no such guards as they hand-feed the cane into the press.  This is a disadvantage of using mechanical advantage.  For it can cause great harm just as easily as it can do useful work for us.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , ,

Beam, Fulcrum, Torque, Law of the Lever and Mechanical Advantage

Posted by PITHOCRATES - May 1st, 2013

Technology 101

A Lever is a Rigid Beam on a Fulcrum

Archimedes said, “Give me a place to stand, and I shall move the Earth with it.”  At least we think he did.  Archimedes of Syracuse was a Greek genius.  Mathematician.  Physicist.  Engineer.  Inventor.  And astronomer.  One of many of the ancient Greeks who advanced modern civilization.  By using math and science.  He did a lot.  And explained why things worked the way they did using math.  Like the Law of the Lever.

In the days before the twist-off bottle cap we used bottle openers.  Because try as we might we could not pry a bottle cap off with our hands.  Most grown men just didn’t have the strength to do that.  But a child could open a bottle if that child used a bottle opener.  For that bottle opener is a lever.  Giving the child leverage.  The ability to use a little bit of force to do a lot of work.

A lever is a rigid beam on a fulcrum.  Like a seesaw.  A common playground fixture.  If two kids of equal weight are on either end of the seesaw and the fulcrum is in the center these kids can effortless push up and down.  But if a grown adult sits on one end and a child is on the other the weight of the adult will drop his side of the seesaw down.  Leaving the child up in the air on the other side.

As the Lever increases in Length the more it will Amplify the Input Force we Apply

Now that’s no fun.  Having the seesaw permanently tipped in one direction.  However, even two people of different weights can enjoy playing on the seesaw.  All they have to do is move the fulcrum towards the heavier person until the seesaw balances.  So that there is a short length of seesaw between the fulcrum and the heavy person.  And longer length of seesaw between the fulcrum and the lighter person.  This creates the same amount of torque on both side of the fulcrum.

Torque is the turning force created by a force acting about a fulcrum.  The force in this case is the weight of the people on the seesaw.  Which we calculate by multiplying their mass by the force of gravity.  With the force of gravity being constant the greater the mass the greater the weight.  This weight pressing down on the beam creates torque.   And the further away from the fulcrum the greater the turning force.  Such that a lighter weight at a greater distance from the fulcrum can balance a greater weight at a shorter distance from the fulcrum.  Allowing a child to play on a seesaw with someone of far greater mass.  Because the lever amplified the smaller force of the child.  Allowing the child to move a heavier weight.  To illustrate this consider the following table.

Lever

This is just a visual aid.  The numbers don’t represent anything.  It just shows a relationship between force and the length of the lever.  In this example we need 1000 units of force to move something.  If we use a lever that is 10 units from the fulcrum we need to apply 100 units of force.  If we have a lever that is 40 units from the fulcrum we only need to apply 25 units of force.  If we have a lever that is 80 units from the fulcrum we only need to apply 12.5 units of force.  As the lever increases in length the more it will amplify the input force we apply.  Which is why a child can open a bottle with a bottle opener.

A Wheelbarrel combines the Lever with the Wheel and Axle

A lever gives us mechanical advantage.  The amplification of a small input force into a larger output force.  Such as a hand-held bottle opener.  But what about the kind that used to be fastened to pop machines?  When you bought a glass bottle of pop out of a vending machine?  The fulcrum is the fixed bottle opener.  And the lever is the bottle.  A can opener was often on the other end of a bottle opener.  Instead of a grip to latch onto a bottle cap this end had a triangular knife.  When we lifted up on the lever it pressed down and pierced a hole in a can.

A wheelbarrel allows us to move heavy loads.  This device combines two simple machines.  A wheel and axle.  And a lever.  The wheel and axle is the fulcrum.  The lever runs from the fulcrum to the handles of the wheelbarrel.  We place the load on the lever just before the axle.  When we lift the far end of the lever we can tilt up the load and balance it over the axle.  The lever amplifies the force we apply.  And the wheel and axle reduce the friction between this load and the ground.  Allowing us to move a heavy load with little effort.

Today’s pop bottles have screw-top caps.  Some people still use a lever to help open them, though.  A pair of pliers.  We use the pliers because we don’t have the strength to grip the cap tight enough to twist it open.  The pliers are actually two levers connected together at the fulcrum.  The pliers amplify our hand strand-strength to get a very secure grip on the bottle cap.  While our hands compress the two levers together getting a firm grip on the cap we can then use our arm to apply a force on the handles of the pliers.  Providing a torque to turn the bottle cap.  Very simple machines that make everyday life easier.  Thanks to the knowledge Archimedes handed down to us.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , ,

Generator, Current, Voltage, Diesel Electric Locomotive, Traction Motors, Head-End Power, Jet, Refined Petroleum and Plug-in Hybrid

Posted by PITHOCRATES - June 6th, 2012

Technology 101

When the Engineer advances the Throttle to ‘Run 1’ there is a Surge of Current into the Traction Motors

Once when my father suffered a power outage at his home I helped him hook up his backup generator.  This was the first time he used it.  He had sized it to be large enough to run the air conditioner as Mom had health issues and didn’t breathe well in hot and humid weather.  This outage was in the middle of a hot, sweltering summer.  So they were eager to get the air conditioner running again.  Only one problem.  Although the generator was large enough to run the air conditioner, it was not large enough to start it.  The starting in-rush of current was too much for the generator.  The current surged and the voltage dropped as the generator was pushed beyond its operating limit.  Suffice it to say Mom suffered during that power outage.

Getting a diesel-electric locomotive moving is very similar.  The massive diesel engine turns a generator.  When the engineer advances the throttle to ‘Run 1’ (the first notch) there is a surge of current into the traction motors.  And a drop in voltage.  As the current moves through the rotor windings in the traction motors it creates an electrical field that fights with the stator electrical field.  Creating a tremendous amount of torque.  Which slowly begins to turn the wheels.  As the wheels begin to rotate less torque is required and the current decreases and voltage increases.  Then the engineer advances the throttle to ‘Run 2’ and the current to the traction motors increases again.  And the voltage falls again.  Until the train picks up more speed.  Then the current falls and the voltage rises.  And so on until the engineer advances the throttle all the way to ‘Run 8’ and the train is running at speed. 

The actual speed is controlled by the RPMs of the diesel engine and fuel flow to the cylinders. Which is what the engineer is doing by advancing the throttle.  In a passenger train there are additional power needs for the passenger cars.  Heating, cooling, lights, etc.  The locomotive typically provides this Head-End Power (HEP).  The General Electric Genesis Series I locomotive (the aerodynamic locomotive engines on the majority of Amtrak’s trains), for example, has a maximum of 800 kilowatts of HEP available.  But there is a tradeoff in traction power that moves the train towards its destination.  With a full HEP load a 4,250 horsepower rated engine can only produce 2,525 horsepower of traction power.  Or a decrease of about 41% in traction horsepower due to the heating, cooling, lighting, etc., requirements of the passenger cars.  But because passenger cars are so light they can still pull many of them with one engine.  Unlike their freight counterparts.  Where it can take a lashup of three engines or more to move a heavy freight train to its destination.  Without any HEP sapping traction horsepower.

There is so much Energy available in Refined Petroleum that we can carry Small Amounts that take us Great Distances

The largest cost of flying a passenger jet is jet fuel.  That’s why they make planes out of aluminum.  To make them light.  Airbus and Boeing are using ever more composite materials in their latest planes to reduce the weight further still.  New engine designs improve fuel economy.  Advances in engine design allow bigger and more powerful engines.  So 2 engines can do the work it took 4 engines to do a decade or more ago.  Fewer engines mean less weight.  And less fuel.  Making the plane lighter and more fuel efficient.  They measure all cargo and count people to determine the total weight of plane, cargo, passengers and fuel.  So the pilot can calculate the minimum amount of fuel to carry.  For the less fuel they carry the lighter the plane and the more fuel efficient it is.   During times of high fuel costs airlines charge extra for every extra pound you bring aboard.  To either dissuade you from bringing a lot of extra dead weight aboard.  Or to help pay the fuel cost for the extra weight when they can’t dissuade you.

It’s similar with cars.  To meet strict CAFE standards manufacturers have been aggressively trying to reduce the weight of their vehicles.  Using front-wheel drive on cars saved the excess weight of a drive shaft.  Unibody construction removed the heavy frame.  Aerodynamic designs reduced wind resistance.  Use of composite materials instead of metal reduced weight.  Shrinking the size of cars made them lighter.  Controlling the engine by a computer increased engine efficiencies and improved fuel economy.  Everywhere manufacturers can they have reduced the weight of cars and improved the efficiencies of the engine.  While still providing the creature comforts we enjoy in a car.  In particular heating and air conditioning.  All the while driving great distances on a weekend getaway to an amusement park.  Or a drive across the country on a summer vacation.  Or on a winter ski trip.

This is something trains, planes and automobiles share.  The ability to take you great distances in comfort.  And what makes this all possible?  One thing.  Refined petroleum.  There is so much energy available in refined petroleum that we can carry small amounts of it in our trains, planes and automobiles that will take us great distances.  Planes can fly halfway across the planet on one fill-up.  Trains can travel across numerous states on one fill-up.  A car can drive up to 6 hours or more doing 70 MPH on the interstate on one fill-up.  And keep you warm while doing it in the winter.  And cool in the summer.  For the engine cooling system transfers the wasted heat of the internal combustion engine to a heating core inside the passenger compartment to heat the car.  And another belt slung around an engine pulley drives an air conditioner compressor under the hood to cool the passenger compartment.  Thanks to that abundant energy in refined petroleum creating all the power under the hood we need.

The Opportunity Cost of the Plug-in Hybrid is giving up what the Car Originally gave us – Freedom 

And then there’s the plug-in hybrid car.  That shares some things in common with the train, plane and (gasoline-powered) automobile.  Only it doesn’t do anything as well.  Primarily because of the limited range of the battery.  Electric traction motors draw a lot of current.  But a battery’s storage capacity is limited.  Some batteries offer only about 20-30 miles of driving distance on a charge.  Which is great if you use a car for very, very short commutes.  But as few do manufacturers add a backup gasoline engine so the car can go almost as far as a gasoline-powered car.  It probably could go as far if it wasn’t for that heavy battery and generator it was dragging around with it.

This is but one of many tradeoffs required in a plug-in hybrid car.  Most of these cars are tiny to make them as light as possible.  For the lighter the car is the less current it takes to get it moving.  But adding a backup gasoline engine and generator only makes the car heavier.  Thus reducing its electric range.  Making it more like a conventional car for a trip longer than 20-30 miles.  Only one that gets a poorer fuel economy.  Because of the extra weight of the battery and generator.  Manufacturers have even addressed this problem by reducing the range of the car.  If people don’t drive more than 10 miles on a typical trip they don’t need such a large battery.  Which is ideal if you use your car to go no further than you normally walk.  A smaller battery means less weight due to the lesser storage capacity required to travel that lesser range.  Another tradeoff is the heating and cooling of the car.  Without a gasoline engine on all of the time these cars have to use electric heat.  And an electric motor to drive the air conditioner compressor.  (Some heating and cooling systems will operate when the car is plugged in to conserve battery charge for the initial climate adjustment).  So in the heat of summer and the cold of winter you can scratch off another 20% of your electric range (bringing that 20 miles down to 16 miles).  Not as bad as on a passenger locomotive.  But with its large tanks of diesel fuel that train can still take you across the country.

The opportunity cost of the plug-in hybrid is giving up what the car originally gave us.  Freedom.  To get out on the open road just to see where it would take us.  For if you drive a long commute or like to take long trips your hybrid is just going to be using the backup gasoline engine for most of that driving.  While dragging around a lot of excess weight.  To make up for some lost fuel economy some manufacturers use a gasoline engine with high compression.  Unfortunately, high compression engines require the more expensive premium (higher octane) gasoline.  Which costs more at the pump.  There eventually comes the point we should ask ourselves why bother?  Wouldn’t life and driving be so much simpler with a gasoline-powered car?  Get fuel economy with a range of over 300 miles?  Guess it all depends on what’s more important.  Being sensible.  Or showing others that you’re saving the planet.

www.PITHOCRATES.com

Share

Tags: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,