Why Planes Don’t Fly Faster

Why Planes Don’t Fly Faster


This is a Wendover Productions video made
possible by Audible. So I recently went down the rabbit hole of
looking at old flight schedules. Airlines used to publish these physical brochures
with their fares and flight times, and when looking at this American Airlines one from
1967 I noticed something interesting. This flight between New York and LA was scheduled
as 5 hours and 43 minutes long—that didn’t seem right. American flight 3 was scheduled to leave JFK
airport everyday at 12 noon and arrive at LAX at 2:43 pm—there’s 3 hours time difference. It turns out that nowadays American Airlines
flight 3 still leaves JFK daily at noon, but the difference is that today, flight 3 is
scheduled to arrive at LAX at 3:27 pm—44 minutes later than in 1967. This has happened across the board—almost
every flight today takes longer than it did back in the 60s. In general the actual flight times—the time
in the air—is the same but with all the congestion and delays at airports the scheduled
times now account for things going wrong. What this means though is that, overall, flying
has slowed down. In 1967 we hadn’t been to the moon and computers
looked like this but we were flying everywhere just as fast or even faster than we do today. What happened that caused this immense lack
of progress in the last 50 years? There are three main types of aircraft engine—the
turboprop, turbofan, and turbojet—and each of them has a range of speeds when they’re
most efficient. The turboprop is the kind of engine you see
on most propeller aircraft. Almost all of the thrust with turboprop engines
comes from the propeller. The turbine which spins the propeller does
intake and speed up some air, but the exhaust air is not at a very high speed so it only
accounts for less than 10% of the overall thrust. These engines are generally inexpensive both
to buy and operate so a lot of smaller commuter planes use turboprop engines. Of course there’s a trade-off—they’re
not as fast. They’re most efficient between about 325
and 375 mph. Any faster than that its better to use a turbofan. Now, these are the engines that you see everywhere. Almost every commercial aircraft is turbofan
driven. With turbofans, the air is initially sped
up by a fan—that’s what you see when you look at an engine from the front. Then, some of the air goes into the interior
combustion chamber where the actual turbine that drives the fan is and the rest of it
goes around the turbine. While air that bypasses the turbine is also
sped up, the majority of the thrust comes from the air that passes through the turbine. Turbofans are most efficient at the speeds
you see most aircraft fly today—400-620 mph. If you want to go supersonic—above 767 mph—you
need a turbojet. Turbojets are very similar to turbofans except
all the air goes through the turbine—no air is bypassed. This lets them achieve extremely high speeds
but they also require an immense amount of fuel. These engines are really only efficient between
about 1,300-1,400 mph. What really determine the efficiency of engines
is something called the bypass ratio. That’s the ratio of the amount of air that
passes through the bypass duct to the amount that passes through the engine core. The thing is, it really doesn’t take that
much more energy to spin a larger fan—what requires a lot more fuel is to put more air
through the engine core. That means that engines that accelerate more
air through the bypass duct can get more thrust for the same amount of energy so, as a rule,
the higher the bypass ratio the more efficient the engine. Take a look at this General Electric GEnx
engine. This is a relatively new super-efficient engine
used on both the 787 Dreamliner and the 747-8i. You can see the fan is much larger than the
turbine itself. That’s because this engine has a bypass
ratio of 10:1—10 times more air goes around the turbine than through it. Compare that to the CFM International CFM56—an
older and less efficient engine. You can see there’s much less fan relative
to the turbine so this engine only has a bypass ratio of 5.9:1, but that’s still considered
to be high. The difference is most striking when comparing
either of those engines to the Pratt & Whitney JT8D. This engine has a bypass ratio of only .96:1
so it’s astoundingly inefficient but its still significantly more efficient than the
Rolls-Royce/Snecma Olympus 593. This engine is a turbojet. As I mentioned, these drive all the air the
fan picks up through the turbine so that means no air is bypassed. Therefore, it has a bypass ratio of 0:1 and
is what’s known as a zero-bypass engine. Since 100% of the air passing through the
engine goes through the turbine, the fuel consumption is significantly higher than that
of the GEnx, CFM56, or even the JT8D. The Concorde, using the zero-bypass Rolls-Royce/Snecma
Olympus 593, burned 46.85 pounds of fuel per mile flown, while the 787 Dreamliner, using
the 10:1 bypass ratio General Electric GEnx, uses 18.7 pounds per mile but the Concorde
was a tiny airplane even compared to the modestly sized 787. It seated only 100 passengers compared to
291 on the Dreamliner. That means that the per-person fuel economy
on the Concorde was just about 14 miles per gallon compared to 104 miles per gallon on
the Dreamliner. In the end, Air France and British Airways,
the only two Concorde operators, could not afford to keep flying the plane. Less than 1/3 of the seats were actually occupied
by paying customers. Others were filled by those using miles or
those upgraded from first class on normal flights. After all, it cost at a minimum $7,500 of
today’s dollars to fly one way from London to New York in those three hours and that
was to fly in seats that looked like this—not all that different than the economy seats
of today. When the Concorde started flying, first class
on other planes looked like this. While nice, these seats were just larger economy
class seats and it wasn’t incredibly easy to sleep in them. By the time the Concorde stopped flying in
2003, first class looked like this and the seats went fully flat into a bed. Many chose to spend a little less to pass
7 hours in this rather than spending 3 hours in these cramped seats. British Airways even introduced the first
fully-flat business class seat in 2000 so for significantly less money than the Concorde,
travelers could cross the Atlantic sleeping horizontally. This just wasn’t luxury anymore. The whole idea of the Concorde was to create
the most efficient way to cross the Atlantic for the business traveller, but with fully-flat
beds, those traveling towards Europe could leave the US in the evening, get their nights
sleep on the plane and wake up in Europe—essentially wasting no time. No longer luxurious or efficient, the Concorde
flew its final commercial fight on October 24, 2003 thereby ending the era of commercial
supersonic flight. Here’s the thing about flying—speed really
doesn’t matter to airlines. It really only exists as a selling point for
the consumer. The cost of the airplane is a relatively small
part of the overall cost to fly so you’ll never see an airline fly faster so they can
use their planes more. Planes lifespans are generally rated in cycles—the
number of times the plane takes off and lands. The Dreamliner is rated for 44,000 cycles
and has a list price, which is often much higher than the actual sale price, of $224.6
million dollars. That means that the cost of the airplane per
flight is barely over $5,000 while the fuel cost for a flight from New York to London
is well over $15,000. Therefore, airlines always just fly their
airplanes at the most fuel efficient speed. It turns out that that speed is just about
always between 500-550 miles per hour. What’s weird about this is that its well
below the speed of sound—767 miles per hour. Why don’t planes fly just below the speed
of sound? Well, this graph shows the drag on airplanes
at different speeds. Between Mach 0.8 and mach 1.2 is what’s
known as the transonic range. At these speeds, the airflow around an airplane
is not fully subsonic or supersonic. Essentially, some air is subsonic and some
is supersonic. So beginning at mach 0.8, some airflow becomes
supersonic which increases drag exponentially and destabilizes the aircraft so its actually
quite dangerous to fly right around the speed of sound—you either have to fly well above
or below. You can actually see when an airplane is flying
transonic. Its hard to see, but there are these lines
that look like scratches on the camera lens but actually are mini supersonic shock waves. Because of the disturbances in the airflow,
flying between mach .8 and mach 1.2 actually requires more fuel than flying above mach
1.2 so that’s why we have this number—613.8 mph—that’s the speed limit for commercially
viable subsonic jets. While supersonic flight and crossing the Atlantic
in 3 hours is flashy and exciting, what’s truly impressive is hopping the pond for $100
or $200 on an airline that’s actually making a profit, and that’s becoming more of a
reality today. With current speeds, airplanes are able to
fly anywhere on earth in 24 hours and that’s fast enough for almost everyone. The barrier to travel for most people is cost,
not speed, so manufacturers and airlines will continue to focus their efforts on driving
down the cost of travel, not the time. In the end, time is the enemy of the privileged
few, cost is the enemy of the masses. This video was made possible by Audible. Audible is the leading online audiobook provider
but I’m sure you already know that. What I’ll tell you is how I use audible. I love reading but there are a lot of times
when I just can’t read a paper book—when working out, doing dishes, even when editing
a video—so I download tons of audiobooks through audible so I can learn no matter what
I’m doing. If you listen when doing tasks like me, you’re
turning what is normally boring into something fun. I recently started listening to Skyfaring—a
book by 747 pilot Mark Vanhoenacker. It gives a glimpse into the pilot’s side
of flying, but its written much more like a novel or memoir than a heavy-duty non-fiction
book. The great thing is that you can listen to
this book for free thanks to Audible with the 30 day free trial you get by signing up
using the link Audible.com/Wendover. It’s a fantastic book and Audible is a fantastic
site so please do at least give them a look over at Audible.com/Wendover. Other than that, you can support Wendover
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you in two weeks for another Wendover Productions video.

100 thoughts on “Why Planes Don’t Fly Faster”

  • There are some blatant inaccuracies in the above video, but like everything else said or written in our world, they can put ANYTHING out there and say it's true, whether it is or not!
    There's no law against lying! So people need to research for themselves IN MORE THAN ONE PLACE to learn from authentic resources, what they can believe or not believe, and take everything else with a grain of salt!!

  • This explanation is partly wrong
    Modern airliners have high bypass ratio turbofans because they are more efficient.
    But the thing about bypass ratio is that, the higher it is, the more the engine turns into a ducted fan, so closer to a turboprop than a turbojet and so less and less efficient at high speeds.

    An old 727 with low bypass turbofans could go up to mach 0.9 while a 320 with high bypass struggles to go up to 0.8, because the engines are inefficient and can't deliver the thrust at these speeds.
    So to fly efficiently you need high bypass, and for a high bypass to be efficient, you need slower speeds.

  • Pedro Réquio says:

    Higher compression ratio=more efficiency, but due to temperature restrains it also means less work or thrust, or more correctly more work per unit of mass flow, so bypass allows for a lot more mass allow higher compression ratios and thus more thermal efficiency. Of course there is more to it like multi stage compressors and turbine, but in rough that's it.

  • Timothy Nechville says:

    The only answer to that Question is Drag!!!! No drag like at 70,000 feet and higher planes Fly very fast with little thrust necessary.

  • alwayz da case says:

    Coz they're bunch of metal sheet,plastic,rubber,glue,glass,bolts,nuts,screws,human flesh and bones on board especially the heavy balls of the pilots flying them

  • You are incorrect at 2:38, the majority of the thrust comes from the fan or air flowing around the turbine. Only 10-20% comes from the turbine exhaust. I have started watching some of your videos and have found a lot of misinformation.

  • Sarmad Hammod says:

    Despite the fact that Concorde was too expensive to fly, I still love it. Its a super-sonic plane capable of travelling much faster than the traditional planes we see today. Travel times are cut in half because of how fast it is. I love it.

  • TheRealCritique says:

    We need to work on tunnels and high speed rail. Airplanes are going to be dinosaurs in the future. We will be using high speed rail, and spacecraft. Much easier to go high speed in a vacuum without air resistance.

  • You are wrong about the" turbofan" aero- engine. The majority of the thrust is produced through the bypass duct not high pressure turbine. They are called high bypass turbofan like RR trent 1000, RR XWB , GNEX and etc.

  • infinitecanadian says:

    I sure wish that they had supersonic transcontinental flight. I want to go overseas some day but would hate having to sit in them cramped chairs for so long.

  • the guy who make this video ….1 star
    fuel cost for an airline to fly london -new york 18272 dollars ….hey retard 3000 dollars goes just for take off :))) depends a lot on how heavy it s …i mean serious you have 4,7 m views and this people believe in your bullshit ….fucking retard

  • I thought the Concorde was retired because of a crash from tire debris on the runway that started the fuel tank on fire?

  • Its quite obvious, the earth is flat and they don't want the masses to be able to fly to the boundaries. Think about that.

  • New Cathay planes can fly much 0.93 (~1100 km/h) and I seen cases where the plane flies at >1000 km/h (possibly over it’s critic Mach number)

  • Remember back in the day on Rockaway beach the Concord would fly over ,never heard a plane that loud until 9/11 when F-16 were flying over Brooklyn.

  • Abílio Esteves says:

    1:40 that’s a piston engine airplane, not a turboprop like you mentioned;
    1:48 you’re referring to the turbine, but are also including the compressor;
    You did a few mistakes trough out the video. Try to be more precise and try to speak with engineers, pilots before making a video about this matter. Googling isn’t enough, don’t be afraid of leaving the front of your computer. Interact with professionals of the subject.

  • There is one very serious error in the stated speeds of this video – the speed of sound AT SEA LEVEL, is indeed, 748 mph, but owing to decrease in density and temperature, it decreases to circa 625 to 630 mph by about 10,000 feet, and stays pretty constant at that value above that altitude. Hence, the airliners are in fact, flying at somewhere between .8 and .9 Mach. As far as the "privileged few" are concerned, you might also take note of the fact that they don't fly any faster, either – business jets that cost as much as airliners, still don't fly supersonic. Geoff Rohde

  • I will be soon releasing a teleporting machine that will put every airplanes out of business. In a blink of a eye you can teleport anywhere in the world as long that location has a teleport reciever.

  • I remember flying in the 60's 737s routinely cruised at 600 mph, they would announce the speeds over the intercom.
    Speeds have slowed because it's more efficient for airlines to do so.

  • Merlin theme Parks says:

    6:50 that is near identical to BA business class, 19 years later!! Good thing we are getting new business class seats soon.

  • Korotkoff Vladislav says:

    Nowadays all really practical projects of supersonic civil jets are all business jets – only if cost of flight is much more than Condorde's, it becomes usable without goverment subsidies

  • 2:38 Incorrect: The air bypassing the combustion chamber and compressors provides the most thrust, like in a Turboprop. This is because the sheer volume of air provides more thrust.

  • Why would people give up speed for comfort (if they can afford speed, that is)? You get to where you need to go quicker…. you don’t need to spend over 10 hours on long haul flights. If you can afford first class on a subsonic plane, I think thats pretty stupid considering that first class is ridiculously expensive anyway and isn’t worth the price. For a smaller price you get to your destination (which could be a vacation, visiting family, etc) faster. I can’t believe people would rather have comfort.

  • Gert Jan Kooistra says:

    You dont have to draw an arch when pointing out from where to where u fly. The Earth is flat so a straight line would do. Natural physic of water it finds and remains level, cant argue nature.

  • lonelyPorterCH says:

    But if they are delayed, do they fly faster to compensate or do they fly faster?

    We had a 1 hour delay today at the start, but I dont know, if we also landed 1 hour too late

  • Levon Alyanakian says:

    Why happened is now, anyone can fly not just the rich, and airlines don’t feel the need to please the middle class

  • How is it possible,for a airliner to carry 32,000 gallons of fuel for a 7 hr flight?,the weight alone at 5.21 lbs a gallon,approx 160,000 lbs,so if this is correct,there would have to be,2- tanks weighing 80,000 lbs. ,1 on each. Wing,cause that much fuel will not fit in the wings,and that much weight,would break off the wings,combined with the weight of plane,and passengers,a plane could not,even leave the ground and trying would,break off the wings,so something isnt correct about the engines and how they work,i know for a fact,when refueling an airliner,never is thousands of gallons pumped into a plane,the only fuel added is starting the engine,after a certain pressure ,compression is reached,the engine runs on the compressed air,for fuel,this is also why they fly a certain speed,the size and number of engines,and size and weight of plane,and the amount being compressed determines the speed of the plane,turbo jet motors,use the air and fuel ,to reach higher speeds,also the cost per gallon at what were told,would be so much,a flyt you couldn't fly anyone,anywhere,the cost of a ticket would be to high,so something is not being told to the masses, and I believe it's to keep everyone paying ,cause the air is free,and fuel costs are fake,and all these years,and tickets sold the airlines have ripped off billions of dollars from all the passengers,saying fuel is the main cost of the airlines,this is why tickets are high?this is just another example of the public being screwed by the airlines owners,federally run airports, with the gov,involved you know ,something not right and somehow there taking you're money,of course I'm stupid,and a retard,besides that,check it out,do the math,nothing makes sense,the flyt times and speed traveling,doesnt add up either,thats a scam also,

  • I wish we could make a modern concorde that has engines that adjust their bypass ratio on the fly, like an SR-71 Blackbird

  • This Video was stolen twice
    Once by Skyships
    Once by BRIGHT SIDE
    Actually the title is stolen from you and the thumbnail from Skyships

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