- The aircraft that you're
seeing here is not just another crazy idea that
someone else dreamed up. No, the Sonic Cruiser
was actually something that Boeing really worked on, even registering patents
to its design and presenting it to their airline customers. - The first unveiling
of the Sonic Cruiser. - And they also took it really seriously. Even though it was never built, many of the technologies
that came from it and even much of the
concepts behind it eventually led to the creation
of an actual Boeing aircraft. Stay tuned. (playful tune) A few weeks ago I launched
a video series here on the channel, called "The Classics", about airliners and other aircraft
that truly left their mark on aviation history. This video is obviously
going to be a little bit different since the aircraft in
it is much more recent and never even entered service but it was still important in its own way. And to start us off and
also give you a little bit of background info,
I am going to talk about an old classic,
although one that, sadly, didn't make a very big
mark in commercial aviation. And that's really a shame
because what I'm talking about is the stunning-looking Convair 990. Now it's fair to say that Convair
isn't a household name today but that wasn't always the case. Convair has plenty of history
as an aircraft manufacturer, going all the way back to World War II. The company was
created from the merger of Consolidated and Vultee
which happened during the war. And later on, they continued making both civil and military aircraft. In the late 1950s, Convair
was very much in its heyday, especially on the military side. They also made some
piston-engine airliners but when it came
to jets, they had been a bit late to the game. Boeing's 707 entered service in October of 1958,
with the Douglas DC-8 following suit around 11 months later. And Convair launched
its own jet airliner, the Convair 880 in May, 1960. Now I've covered the story
of the 707 which was obviously the undisputed king
of this first generation with over 1,000 of them entering service and then came the DC-8
which came in second with just over half as many produced but the Convair 880, unfortunately, was widely regarded as a failure with only a measly
65 aircraft built in total. So why was this then? Well, to start with, the 880 had a five-abreast economy seating, unlike the DC-8 and the 707,
which sat six passengers on each row and this seems
to have been a big factor in the jet's poor sales performance. It was just considered too small. And with a capacity
of only 110 passengers, it was never going to be anything else. And on top of that,
it also had a shorter range than both of its competitors but it was a little bit faster than them. Beyond that, the only really
notable thing about the Convair 880 was that Elvis Presley
actually bought one. The aircraft remained in production
for only around three years and ultimately created
a big loss for Convair but the company still believed
that they had a solid design so they wanted to
try to find a fix for it. Since Convair couldn't compete
with the others on efficiency, they thought that they
could maybe make a niche in the speed department instead. And since the 880 was
already a bit faster than the others, Convair marketed their new model, the 990,
as an even faster jet, with enough range to complete
transcontinental journeys. The 990 was a bit longer
than its predecessor and was modified further to increase both its range and speed. The goal was to be able to fly
150 passengers against the wind on a westerly route, for example
from New York to Los Angeles, non-stop with a cruise
speed of Mach 0.89. These specifications proved to be a bit harder than Convair thought when they first started. But the company really
tried to achieve them. The 990 had a very Innovative
early turbofan engine design, instead of the 880's turbojets
and it also featured a set of very distinctive pods on
the upper rear side of its wings. These were called anti-shock bodies and their purpose was
to reduce wave drag which happens when part of the airflow of the wings starts to move
faster than the speed of sound. These transonic shock waves
is something that you, as a passenger, can actually
sometimes still see on the top of even today's airliners. It often looks like a thin optical line that dances parallel to the wing's
leading edge about a quarter or a third in on the wing. The design of these anti-shock bodies was based on research
that was brand new at the time, involving
something called the area rule and we'll get back
to that a little bit later but as you have probably guessed, the idea didn't really catch on. Some newer airplanes actually
did use some other variations of the anti-shock bodies, combined with the flap track fairings but, in general, today
we don't really need them because most planes
don't fly fast enough for them to make a real difference and aircraft using supercritical
wings don't need them at all. The Convair 990 did enter service
with American Airlines and Swiss Air but in terms of sales, it did even worse than the 880 with only 37 aircraft built. American Airlines were
thinking of buying more of them but scrapped that idea when the aircraft never really met its
promised specifications. It turned out that, in practice,
the Convair 990 would cruise at Mach 0.84 which was comparable to that of the DC-8 and the 707. It is a real shame
that it didn't do better because period footage
of it shows what looks like a really comfortable cabin. Convair made barely over
100 880s and the 990s combined and they never made
another passenger airliner after this fiasco. After multiple mergers and acquisitions, the Convair name
slowly faded into history while its former facilities
and operations eventually got sold to either Lockheed
or McDonnell Douglas. The story of the Convair 990 foreshadowed what eventually would also happen
to aircraft like the Concorde, the Tupolev 144 and even
the canceled Boeing 2707-SST. As it turns out,
airlines and passengers were more interested
in efficient, affordable travel rather than a truly fast aircraft. So with this being a video
about Boeing's Sonic Cruiser, at this point, you might think
this will be a very short video, right? Well, not so fast. It is impossible to understand
the Sonic Cruiser project just by looking at aircraft designs from the 1950s and '60s. In order to really understand it, we need to first look at another
aircraft development race that took place in the 1990s. And before we do that there's this: What is actually the best way
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supporting my work. Now let's continue. When Boeing first
presented the Sonic Cruiser on the 29th of March, 2001 some critics said that they thought it was a three-days-early
April's Fool joke. But it turns out that Boeing
were completely serious. In 2001, Boeing had already
absorbed McDonnell Douglas, a move that would later be criticized by many as a step away from its past as an engineering-led company and towards one that was
more ruled by Wall Street. But the events that led to
the Sonic Cruiser project really involved the
original engineering-led and truly innovative part of Boeing. And as strange as it sounds, the aircraft that pushed
Boeing down the path towards the Sonic Cruiser
was a competitor design that we today know as the Airbus A380. Yes, this takes us
back to the mid-1990s when Airbus was talking to the airlines about what they called the A3XX. This was the start of the
epic battle of the super jumbos because when Boeing
learned of Airbus' plans for a double-decker aircraft, their engineers initially wanted
to compete by launching one or even more enlarged 747 variants. When we talk about this,
it's worth remembering that since the launch
of the 747 in the 1960s, Boeing had never extended
the length of its fuselage. The 747-300 and 400
had a longer upper deck but the overall length
of the plane did not change. The only exception to this
was the shortened 747SP which I've talked
about in a different video. But during the super jumbo battle during the mid-1990s,
it seems like Boeing was going to finally change that. In 1996, Boeing revealed plans
for three possible enlarged 747s, called the 747-500X, 600X and 700X. The first two would feature
a new wing and a fuselage that was to be slightly
extended by different amounts and then the 700X would take things even further with both
a longer and a wider fuselage. Boeing worked on these designs
for years but ultimately concluded that there wasn't really
a market big enough to support the plans for
these super-sized 747s. Later, Boeing instead came up with a more modest
747 enlargement plan where they would modify
the existing 747 wing and have a more modest fuselage stretch but fit some new engines
and avionics to it but the fact that even that plan failed to gain any interest from the airlines, confirmed something
that Boeing's engineers and researchers had been
suspecting for a while. The way that the Airlines and passengers were flying long haul was changing. Now it's also worth to point out here that all of this development work
was taking place at a time when there was still some resistance to the idea of more generous extended-range twin-engine
operations performance standards or ETOPS for short. These ETOPS rules now allow
twin-engine aircraft to fly in routes over sea
with no alternates close by. But in the mid-1990s,
it still wasn't clear how easy it would be for new airliners to get ETOPS approvals good
enough to make them viable. Airbus betted that quad-jets
like the 747, the Airbus A340 and later, the A380, would continue to rule the skies over the oceans and therefore, be the
only logical way forward. But, by contrast, Boeing made sure that when their 777
entered service in 1995, it did so with a full
180-minute ETOPS approval. That meant that
it was allowed to operate three hours away single-engine speed from an alternate and, therefore, making it viable for
basically any oceanic trip. The airlines really liked the 777 design and pressured Airbus to give the same treatment to its Airbus A330 but Airbus refused
and instead continues to push the four-engine A340
for long oceanic trips. And this gave Boeing's
engineers an idea. The 777 was obviously a twin-jet but it was still relatively big. If they could design another twin, smaller, but still with long enough range to work for long haul
and make it fly faster, they could give the airline something they could really use
to connect smaller cities directly instead of flying
through big airport hubs. Yes, this was indeed another chapter in the battle between hub and spoke, the traditional way for
long-haul travel for airlines and the point-to-point model
which was the up and coming one. Passengers seemed to mostly prefer the point to point because that meant that they didn't have to
change flights halfway through which made their travel quicker so it looked like speed and convenience still maybe was a strong bargaining chip. And this finally brings us
to the purpose of the Sonic Cruiser. Since both the airlines
and their passengers liked the speed of point-to-point travel, why not compound the speed further by making a really fast twin-jet,
one that would cruise at Mach 0.98? Now those of you who did physics at school know that going fast comes with a fairly big penalty. Drag increases with the square of speed, meaning that when
you double the speed, drag gets four times bigger. But Boeing's engineers had some
very good reasons to believe that they could pull this off without making the Sonic Cruiser inhibitively fuel thirsty. First, there was some fresh research from NASA on the topic
of transonic and supersonic travel as I explained in my video
about the Tupolev 144 but the main factor
that made Boeing's engineers favor the Sonic Cruiser concept was the use of composite
materials like carbon fiber. Composites can make for lighter structures which helps to reduce the fuel burn but they also have a
few more characteristics that would make them key for this type of aircraft
because composites can also be useful when engineers want
to build large complicated shapes and this is particularly true
for pressurized structures like an aircraft fuselage. And to understand why
that is so important, we have to return back to the area rule that I mentioned before. Now imagine slicing an aircraft
like a cucumber, front to rear, including the fuselage its wings
and control surfaces, et cetera. What the area rule says is that
the cross section of each slice should increase and decrease
as smoothly as possible from nose to tail. This will minimize wave drag
which is a huge factor when the aircraft starts
to move into the transonic and, subsequently,
the supersonic speed regime but what this means in practice is that, for example, where
the fuselage meets the wing, the fuselage should get a bit slimmer to account for the thickness of the wing. This would require the fuselage
to have this thin waist where it meets the wing,
basically a Coke-bottle shape and you can actually
see exactly this shape on some supersonic military jets. The Convair F-102, for example,
was redesigned during development with a Coke-bottle fuselage
to better conform to this rule. But fighters and other military jets that follow this rule have only
a pressurized cockpit. Unlike an airliner, they don't need to pressurize the rest of
their sculpt and curb fuselage. This is why, for example, the Concorde had a perfectly straight fuselage
even though its engineers absolutely knew about the area rule and could have used
it to make Concorde even faster and more efficient. But they were working with aluminium plus they also had to deal
with the high temperatures associated with flying at Mach 2. So they had to settle with
this simpler straight design instead of using the area rule. But with these new fantastic materials, the Sonic Cruiser would not be
bound by these same limitations as the earlier types had been. But remember Boeing had already been bitten by supersonic
airliner endeavors earlier, with the failed Boeing 2707 SST. As I explained in my recent
video about that aircraft, it was simply too ambitious,
being both bigger and faster than the Concorde and it
nearly bankrupted Boeing when it was canceled. - And we are talking about a plane in the end of the '60s
that will move ahead at a speed faster than Mach 2
to all corners of the globe. - So this time, Boeing's engineers
thought that they would play it safe, adapting existing research
to a much more conservative design. This design would
not be quite supersonic. It would instead cruise at Mach 0.98, so close to Mach 1 and that just
make things much, much easier. It would for example enable them to more easily use
high-bypass turbofan engines. And it would also solve a lot of the friction-temperature-related problems that would come with supersonic speeds. Boeing was betting big
on composite materials in this design which they saw as the ideal solution
for this type of use. A Boeing patent from back in the day when the development was going on, gives us a lot of insight
into how the design features of this aircraft would have
made it operationally-feasible. They also showed the importance that Boeing's engineers placed
on the area rule and how they would take advantage of it. Now, as a general rule, it's a bad idea to fully trust patent documents because they often exist just
to lock down certain features, not to show a true
depiction of an actual plan. In fact, they often can be deliberately misleading in that regard. But looking at the general configuration of the Sonic Cruiser, its fuselage was going to be wide near the nose then as the delta wing got broader, the fuselage slowly started
to taper, growing thinner. The rest of the aircraft's configuration also had some features
of supersonic jets, like the delta wing and
the canards near the nose who actually looked a bit
like all the ones on the Tupolev 144 except that these ones
wouldn't be retractable. And, crucially, the Sonic Cruiser
will have two engines, not four, both of them buried into
the rear structure of the aircraft so that their intakes
were below the wing. Boeing's engineers really believed that they could offset
the higher fuel consumption associated with flying at Mach 0.98 by simply optimizing the aerodynamics of the Sonic Cruiser and airlines like Virgin Atlantic and American Airlines were really enthusiastic
about this new design and also none of those airlines
had showed any real interest in the Airbus A380, making them perfect customers for Boeing's
now radically-different market idea with the Sonic Cruiser. And, incidentally, Airbus announced its A380 formally just days
before Boeing unveiled the Sonic Cruiser for the first time and that was probably not a coincidence. A smaller, very fast,
point-to-point airliner was really attractive to a lot of people and, obviously, it was an example of a forward-thinking,
engineering-led Boeing Company that really contrasted
themselves from Airbus. So why didn't it happen? Well, there are a few reasons for this. Firstly, some analysts believed
that Boeing's numbers for the aircraft's range and speed and, therefore, its efficiency
likely were a bit optimistic. Boeing had been adamant that the aircraft wouldn't
be less efficient than other aircraft flying at the time
and that likely didn't really hold up. And with that, like Convair discovered with the 880 and 990 designs, the airlines simply preferred
the extra efficiency that they could gain at a slower speed
and, obviously, the extra range that would come with that. And also, in reality, the benefits of flying a bit faster
weren't as earth-shattering as Boeing's researchers had thought. For a 3,000 nautical-mile journey between New York and London,
for example, a typical jet today would take between six and seven hours to complete that flight. In practice, the faster speed
of the Sonic Cruiser would reduce this by around one hour, meaning a time saving
of around 20% or so. Now I'm sure that many
of you would appreciate that but for the airlines,
making such connections work would run into some operational problems. Scheduling these faster flights
so that they would depart and arrive at the right
time for each time zone is a bit more complicated
than it actually seems. And this is especially true
when you consider that the airline would also have to fit the schedule
to their Sonic Cruiser alongside the rest of their non-Sonic-Cruiser fleet. And, finally, another reason
why the Sonic Cruiser project was scrapped was that it was
just having some really bad timing. As I'm sure some of you noticed when I've said it earlier,
Boeing unveiled it in March, 2001 and a few months later, 9/11 would completely
change aviation forever. With many airlines struggling
to survive after that, suddenly the idea of a super sleek, super fast but somewhat
ambitious airliner just made no sense. But for Boeing,
the Sonic Cruiser program was not a complete loss. Their ideas about the point-to-point versus hub-and-spoke operations were fundamentally correct
and their technological advances on composites were
absolutely on the money. As I'm sure many of
you know, all of these ideas and technological advances
ultimately led to the 7E7 concept with E meaning efficiency. That aircraft is flying successfully
today as the 787 Dreamliner. Its composite fuselage
which made its large windows possible and its use of electrics
instead of bleed air to pressurize the cabin and power
many other systems are all ideas that Boeing started developing
for the Sonic Cruiser. They just had to adapt
them to a shape closer to what they already knew. Now I hope that you liked this video and if you did, leave a like, a comment and subscribe to the channel. If you want to support the work
that me and my team does, then please consider joining
my awesome Patreon crew. I have lovely Zoom hangouts
with them whenever I can and I've just finished sending out
this year's Patreon gifts for those who have
registered addresses. Now check out these videos
next which I know that you'll like and buy yourself a Classic t-shirt. There are links to it
in the description below. Have an absolutely fantastic day
and I'll see you next time, bye-bye.
