WHY Did The Tupolev Tu-144 Fail?!

- Was it a technological marvel that nearly succeeded, or simply a product of espionage? There are a lot of questions and misunderstandings about the Tupolev-144 or Concordski, as many of you might know it. But perhaps the thing it is most remembered for was a tragic, fatal crash that happened at the 1973 Paris Air Show, almost exactly 50 years ago.

Stay tuned. (delightful tune) The allure of supersonic passenger travel wasn't unique to the makers of the Concorde. I just did a video about the mysterious Everglades Jetport and how it was deeply connected to the American efforts to create their own supersonic airliner.

But what about the Soviet Union? In the early 1960s, the Soviets also had a very busy aviation industry that had created a number of attention-grabbing aircraft, both civilian and military. And since it was public knowledge that the British and the French were working on a supersonic passenger aircraft, the Soviets weren't just going to be sitting on their hands.

Now, you might think it's a little bit weird that the Soviet Union would even be interested in a design like that, something that would carry relatively few passengers over just medium distances. But the Soviets knew the propaganda value of launching such a design, especially if they could do it before the West. And they weren't just about to throw in the towel.

The Soviet Union launched the Tupolev-144 program in July, 1963, just six months after the launch of the Concorde program. And after a surprisingly fast development, even by the standards of that era, the aircraft flew for the first time on the 31st of December, 1968, about two months before the Concorde did. But from the very start, there were suggestions that the Tupolev-144 managed to beat the Concorde to the air simply because of either espionage or because its development was really rushed, resulting in an aircraft too immature to be really useful.

With that criticism in mind, let's look at what the Tupolev-144's specifications actually were and how they compared to the Concorde's. To start with, the Tupolev-144 was a bit bigger than the Concorde. It was around 4 meters or 13 feet longer and with a wingspan just over 3 meters or 10 feet greater than the Concorde.

As a result, Concorde had a single aisle cabin layout with two seats on either side of the aisle in what was essentially an all-business cabin. This gave the Concorde a capacity of 100 seats, although in theory, it could probably squeeze in a few more if needed. But by contrast, the Soviet jet actually had a two-class cabin, with five seats on each row in second class and three seats across in the first class.

This meant that in total, it had seats for 150 passengers, making its passenger capacity 50% higher than the Concorde. The 144 was actually also a little bit faster. You see, Concorde's designers had picked a cruise speed of Mach 2 specifically to be able to use aluminium throughout which was a much better understood material and easier to work with compared to the more exotic titanium which the Soviets favored.

What this meant was that in practice, Concorde's speed was temperature-limited to Mach 2. 04, although it could fly a little bit faster in the right conditions. The Tupolev-144 instead used titanium and steel for its wing leading edges and also in some other areas where they were subjected to higher friction heat in cruise, and this enabled it to cruise at Mach 2.

15. But in practice, it cruised at Mach 2 just like the Concorde. Having looked at all of that, you could say that the Tupolev-144 was actually a bit more ambitious than the Concorde, but not quite as extreme as Boeing's plans for the 2707 SST.

Like I mentioned in my last video, in their most conservative plans, the American SST was supposed to fly at Mach 2. 7, using a wide body construction, carrying 230 passengers. But as we all know, that never happened.

But now we get to the range. And this is where the specs of the Tupolev 144 actually starts to fall behind those of the Concorde. Even in its final D version, which actually never got to carry passengers, the Tupolev-144 couldn't fly further than 3,500 nautical miles.

And that's to be compared with the Concorde's 3900 nautical miles. Now, that might not sound like a huge difference. But it meant that the Concorde could fly across the Atlantic while the Tupolev-144 just couldn't.

But was this really a deal-breaker for the design? Actually, no. And that's because the Soviets were planning to use the aircraft a bit differently from the way the British and the French were.

And that strategy difference could have easily tipped the balance into the Soviet jet's favor. And I'll explain all about that after this. So, today, I want to share an amazing resource with you that has been a real game-changer for me personally, and that's Brilliant, today's sponsor.

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So, thank you Brilliant for your continuous support of the channel. Now back to the video. A key factor that could have helped the Tupolev-144 to become successful was simply geography.

Unlike Britain and France or many other countries with early orders of the Concorde, the Soviet Union was huge. And this meant that the use case for the Tupolev-144 was radically different than the Concorde's. Simply put, the Soviet Union was so big that a supersonic airliner would be quite handy for domestic trips.

But then you might ask, doesn't that mean that the Soviet jet would have to fly at supersonic speeds over land? Well, this was a big no, no for the Concorde. And those who were passengers on ships and heard it crossing the sound barrier over them will tell you why that was.

(thunderous boom) (people chattering) Now, it turns out the Soviets weren't as worried about Mach busting some small towns. When it was in service with Aeroflot, the airline primarily flew it over sparsely populated areas. But beyond that, they didn't really have any limitations.

And when it came to international travel, the Tupolev-144 would eventually have been able to fly from the eastern reaches of the Soviet Union to destinations in Asia by going supersonic over water. Another difference between the Soviet Union and the West, which would come into play a little bit later, was of course, the fuel prices. Because even after the Yom Kippur War in 1973 and its effect on fuel prices worldwide, the Soviet Union wasn't as affected as the rest of the world because of its domestic oil production.

And this meant that a lot of the factors that would spell real trouble for supersonic jets in the rest of the world could be more manageable for the Soviets, at least in certain extent. So, to recap, the Tupolev-144 actually had a solid use case that would have allowed both Aeroflot and its manufacturers to gain experience in passenger supersonic flights. This could have possibly given them the opportunity to slowly improve its range and capacity over time.

So, what happened? Well, to try to understand this, we have to look a little bit closer at the aircraft's actual design. Other than the size difference, the Tupolev-144 and the Concorde look really similar, but there are some big differences.

Obviously, they both use a delta wing, which isn't actually that surprising because most designers of supersonic jet projects turn to delta wings to meet the radically different lift and drag requirements between a supersonic cruise at Mach 2 and the much lower subsonic aerodynamics used during takeoff and landing. Concorde was equipped with what's called an ogee-shaped or S-shaped delta, which made it behave well in a range of different center of gravity configurations and also provided a relatively low landing speed at a high angle of attack. But by contrast, the Tupolev-144's wing design was much simpler.

This meant that it needed canards, that's those smaller wings on its nose, to improve its low speed characteristics and to reduce its takeoff and landing speeds. The first prototype, by the way, didn't have those canards. That really first only appeared on the production variant of the jet.

But the canards also added weight. And to keep them from producing drag in cruise, Tupolev designed them to be retractable, which added even more weight. And even with the canards extended, the Tupolev still needed to land at a higher speed than the Concorde did, requiring longer landing distances, more durable tires, and a brake parachute.

The other key to why the Tupolev-144 didn't have the range of the Concorde had to do with its engines. In theory, the first engine the Soviets fitted to the 144 was actually more advanced than the Concorde's. This was a low bypass afterburning turbofan called the Kuznetsov NK-144.

By contrast, the Concorde had the Rolls-Royce/Snecma Olympus 593 turbojet which was a rather mature design. Basically, an evolution of the engine for the Avro Vulcan Bomber, which first flew already back in 1952. Obviously, the Concorde version was substantially improved.

But more importantly, this engine was a much better choice than the theoretically more modern turbofan of the Tupolev-144. But how does that make any sense? All airliners today have turbofans, not turbojets, right?

Well, yes, they do and that's because, as I've explained in other videos, it's normally more efficient to push a larger amount of air backwards at the same speed than to push the same amount of air backwards at higher speed. That's why turbofans today are getting bigger and bigger in diameter, with more and more air bypassing the turbine itself, which is known as a bigger bypass ratio. But this assumes that we're flying subsonic like today's airliners do.

At supersonic speeds, this larger frontal area of high bypass turbofans can actually start to become a problem, adding much more drag. Now, obviously, I'm oversimplifying this a little bit. There are many supersonic military jets today with afterburning low bypass turbofans, but at the time that this was happening, getting those type of engines to work efficiently was really, really hard.

All this meant that Tupolev would eventually also adopt a turbojet engine for the 144 called the Kolesov RD-36-51. But this came much later. All Tupolev 144 passengers flew on the original, less efficient turbofan version.

And actually, it's not just the engines themselves that ended up hurting the 144's efficiency and range. There was also another issue with these engines which had to do with where they were placed. As you can see here, the four engines on the Tupolev-144 are much closer to the aircraft's center line than the Concorde's are.

Now, we pilots like having the engines close to the plane's center line because that means that we don't have to worry as much about asymmetric thrust if one engine were to fail. But it seems like the main reason why the Tupolev engineers put the engines where they did was because they wanted, or rather needed, the engine air intakes to be very long. I will eventually do a video focusing more on Concorde itself where I'm going to go into this in more detail.

But what you need to understand here is that the Concorde's engine intakes were key to its success. Concorde was the first airliner to have an analog fly-by-wire control system. But it also had an inlet-by-wire.

And why was that? Well, if you think for a minute about how much air a jet engine actually needs to operate properly. During takeoff and at low speeds, it really needs all of the air that it can get.

But as soon as the aircraft's speed starts coming close to the speed of sound, designers needed to make sure that the air going into the engine was not supersonic. Obviously, on normal airliners, this isn't really a problem because we don't go supersonic. Fighter jets and other supersonic jets have their own ways of dealing with this problem.

But in practice, really fast and big supersonic jets needs engine inlets that can change their geometry at different speed regimes to make sure that their engines can continue to function properly. Both the Concorde and the Tupolev-144 had variable geometry inlets. The inlet-by-wire system in the Concorde controlled the inlets and various gates at different speeds and conditions, including after an engine failure at high speed.

And crucially, they also helped make the engines more efficient in cruise by increasing the overall pressure ratio. But the inlets on the Tupolev-144 were much simpler. So, to help control the airflow and keep it more consistent, the Soviet engineers made the inlets really long, twice as long as on the Concorde.

But this additional length also added a lot of drag. What all of these issues actually meant was that to sustain the necessary power in cruise, the Tupolev 144 needed a little bit of afterburner continuously. An afterburner works, simply put, by dumping extra fuel into the back of the engine nozzle and then burning it.

This generates more thrust, but at the price of a much higher fuel burn and noise. And speaking of exhaust nozzles, the ones on the Concorde also had a variable geometry which not only made it more efficient, but it enabled reverse thrust on landing, which was another thing missing from the Tupolev. That's partially why it needed those drag parachutes after landing.

The lack of reversers might also have been why the Tupolev-144 had a unique eight-wheel main gear boogie set up, possibly to allow for better braking. Although that gear design might also have to do with the way it retracted into the fuselage, requiring relatively small diameter wheels and tires. But according to some analysts, the main problem with the Tupolev-144 was just the rush of its initial development.

It seems that completing it and getting it into the air before Concorde was a highly politically-charged decision. And this takes us to that fateful Paris Air Show on the 3rd of June, 1973, 50 years ago. Both the Concorde and the Tupolev-144 were scheduled to perform back-to-back shows, meaning that effectively, the show became a contest between the two.

Unlike Concorde, the Tupolev didn't have a fly-by-wire system, but it had a simpler stability and control augmentation system. For the air show, it appears that some protections and limitations in this system were turned off, possibly to allow for more elaborate and eye-catching maneuvers. The Tupolev pilots had performed their air show once already the day before without any type of issues.

But on the 3rd of June, just after the Concorde's performance, the Tupolev-144 crew appeared to make an unscheduled steep climb near the end of their routine, which had not been part of their show the previous day. This was then followed by a very steep dive. And it appears that the airframe of the 144 became overstressed when its pilots tried to pull out of the dive, causing it to completely break apart.

The aircraft hit the ground, instantly killing all six crew members on board and causing eight more fatalities on the ground. The investigation into the crash didn't end up reaching a definitive conclusion as to what caused it, and this gave rise to several conspiracy theories. Some claimed that a French fighter jet was flying too close to the 144 in order to photograph its canards, surprising the Soviet pilots and leading to that final maneuver.

In the Soviet Union, some would later claim that the British and French deliberately let Soviet spies steal compromised Concorde files to lead engineers into making a faulty aircraft, which actually sounds insulting both to Western and Soviet engineers, to be honest. There were also theories around construction methods, metal fatigue, or issues involving the bypassing of the stability system. But in any case, Tupolev, after the crash, ended up strengthening the structure and modifying the flight controls to make overstressing the aircraft much more difficult.

When it came to actually making the aircraft useful, both the Concorde and the Tupolev took a very long time to enter into service. And when they actually did, the Tupolev again beat Concorde by one month; well, sort of. In reality, when the Tupolev-144 entered service in December of 1975, it only flew mail and cargo, basically continuing its test program.

It actually started flying passengers in November of 1977, well after the Concorde did. As for what it was like to fly in, apparently, its pilots were kept really busy because the design was still in its infancy and reliability always remained a problem. But probably the best known problem it had at least from a passenger perspective, was its cabin noise, which was so bad that people famously had to pass handwritten notes to each other in the cabin in order to communicate in flight.

This had partly to do with the continuous use of afterburner in cruise, something that Concorde only needed during takeoff, but also with the position of the engines and a very noisy cabin pressurization system. In the end, the Tupolev-144 would stop flying passengers after just seven months, or 55 flights. This happened after a second accident, a crash landing that took place in May of 1978 during a delivery test flight of the improved Tupolev-144D variant.

After an undetected fuel leak, the aircraft caught fire. And two flight engineers perished in the crash, while six others on board survived. Even though the cause of the crash only affected this new variant, it appears that by this point, the Soviet leadership and Aeroflot had simply had enough.

The Tupolev-144 never flew passengers again, even though some freight and mail flights restarted eventually. Later on, another incident included an uncontained compressive disk failure in August of 1980 which happened during cruise at supersonic speed. Another aircraft also suffered some minor structural issues.

So, in total, the Tupolev-144 fleet made just 103 revenue flights, including cargo. But plans to bring it back to service did persist. We know that because its production officially didn't end until 1982.

And after that, it only got some use as a test bed, including for pilots of the Soviet Buran space shuttle. There were other plans for more versions of the aircraft, including military ones, but the Soviet Air Force and Navy just weren't that interested. And more recently, there were actually thoughts to revive the program or launch its successor, called the Tupolev-244.

That version would use hydrogen burning engines and some technology borrowed from the Tupolev-160 bomber, but it also didn't go anywhere. And in a really, really odd twist, especially given the current geopolitics, the last user of the Tupolev-144 actually was NASA. - A new period of cooperation in aeronautics between Russia and the United States.

- This was part of a program that NASA called the High Speed Civil Transport. In that program, the last Tupolev-144 ever made was refurbished and fitted with new afterburning turbofans borrowed from the Tupolev-160. The plane was flown within Russia from 1996 until 1999, when NASA ended the program.

Today, a number of Tupolev-144s are showcased in various museums, just like the Concordes are. So, was this aircraft just another failed supersonic project, or even the product of espionage? Well, sadly, it seems like this interesting plane was seen by those in power mainly as a propaganda tool, which no longer really mattered after its initial successes and failures.

As for the espionage question, ultimately, it didn't really matter. In the end, it was the execution of the project and the poor support that killed it, rather than anything to do with its origins. Now, I really hope that you liked this story.

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