The Concorde didn't fly supersonically above land, it only could above the ocean. The Tu-144 however flew between Moscow and Almaty, so entirely above land; why did it fly like this? Didn't it have a that loud sonic boom? If no, why not? If it had, why did it fly above land anyway while the Concorde refused to go supersonic above land?
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83$\begingroup$ In the soviet union nobody was going to complain... $\endgroup$– GdDCommented Dec 16, 2020 at 13:06
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12$\begingroup$ I don't understand the downvotes. What's wrong with my question? It asks on whether there may have been a technical advantage over the Concorde that allowed it to fly above land. Tu-144s seemed to be more progressed anyway. $\endgroup$– GiovanniCommented Dec 16, 2020 at 14:25
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15$\begingroup$ I don't know for sure @Giovanni, I didn't downvote but I didn't upvote either. My constructive feedback is that your question needs a bit more research. Did the Tu-144 fly supersonic on it's regular route? Did the route take it over major population centers or were they avoided? You need to account for the nature of the soviet union as well, people were hardly in a position to complain. $\endgroup$– GdDCommented Dec 16, 2020 at 14:29
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6$\begingroup$ @Giovanni Your question assumes a technical difference, but it was actually a political/legal difference. $\endgroup$– StephenSCommented Dec 16, 2020 at 17:23
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21$\begingroup$ @Giovanni: I suspect the downvotes, like mine, are because the answer is so blindingly obvious, and belongs on the Politics site (or perhaps History). To repeat what others have said, this was the Soviet Union. $\endgroup$– jamesqfCommented Dec 16, 2020 at 18:22
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5 Answers
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The actual 'legal' reasons have already been mentioned. However, there was a bit more to it.
- Tu-144 was meant to fly over land from the beginning; there was no way around it, unlike Concorde. So it was designed to fly higher. In particular, Tu-144 had about 20% lower wing loading and 20% higher thrust-to-weight ratio (at MTOW) than Concorde. (The reality was a bit more complicated; for example, Concorde was limited to FL600 again for 'legal' reasons, due to certification of the pressurisation system AFAIK).
- Soviet citizens, apart from not being asked their opinion, were quite used to sonic booms from military aircraft. In many places of the country, they wouldn't even raise an eyebrow. In the Urals where I grew up, I heard them almost daily.
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6$\begingroup$ Concorde was also meant to fly over land. Many of the intended routes were between Europe and Asia and cross-continent in the USA. $\endgroup$– jwentingCommented Dec 17, 2020 at 14:34
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4$\begingroup$ Your answer, with the personal experience, is the most useful IMHO. $\endgroup$– J.HirschCommented Dec 17, 2020 at 22:40
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2$\begingroup$ Regarding the last point: This is certainly true for other Eastern bloc countries too. In the GDR I heard supersonic booms every Wednesday, when an Soviet airfield nearby had their flight training day. $\endgroup$– lejonetCommented Dec 18, 2020 at 14:03
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2$\begingroup$ When I grew up in the 1980s sonic booms were quite usual in the northern FRG, too. I am too young to actually remember, but in my memory it was a daily thing. The disregard for civilians on the ground was not a Eastern Bloc thing, it was a cold war thing, or an 80s thing... $\endgroup$ Commented Dec 18, 2020 at 22:27
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3$\begingroup$ @I'mwithMonica, As an American who visited FRG in the late 80's, I was shocked by the number of sonic booms I heard every day. I never heard one at home, despite living within 50 miles of 2 major USAF bases. It was a Cold War thing, but the burden wasn't shared equally by all participants in the Cold War. $\endgroup$ Commented Dec 19, 2020 at 17:22
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The Tupolev Tu-144 was just as loud as the Concorde. As it was already pointed out, the Concorde was legally prevented from going supersonic over land by the US, UK, but it was more than capable of going supersonic over land. There were no similar restrictions over the Soviet Union for the Tu-144. Both planes had a sonic boom.
The plane's chief designer, Alexei Tupolev, whose father Andrei designed the first Soviet jet, was aboard and acknowledged the noise problem, saying it was inevitable with supersonic flight.
"The sonic boom is no different that a thunderclap - so it is no different than nature itself," he said.
From what I can determine, the noise from the Kuznetsov NK-144A turbofan engines that powered the Tupolev Tu-144 were not quiet and comparable to the noise of the Concorde with Rolls-Royce/Snecma Olympus 593 engines at takeoff produced 119.5 decibels. There is no side-by-side comparisons of the noise.
The Tu-144 was much louder inside during flight because of the amount of air it needed to move to keep the skin cool. The Concorde used more advanced cooling methods to keep the interior noise down.
One additional point is that each of the four NK-144A engines produced 6,000 lbs of thrust more than the Olympus 593. Even though the Tu-144 weighed 22 tons more than Concorde, it never really flew at full capacity, so it had a substantial kick during takeoff.
Now if I could just go on a flight with either plane.
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11$\begingroup$ The sonic boom is generated by the front of the plane pushing air faster than it can move away. It will generate one even if the engines made no noise. $\endgroup$– NelsonCommented Dec 17, 2020 at 13:42
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6$\begingroup$ plus a million for that last sentence m'man - shed a tear for the lost days of speed $\endgroup$– FattieCommented Dec 17, 2020 at 14:08
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4$\begingroup$ @Fattie: What speed? The Concorde & Tu-144 don't go any faster, perceptually, than a subsonic commercial airliner. If you want fast in an airplane, take your Piper Cub out and fly with the wheels in the sagebrush. $\endgroup$– jamesqfCommented Dec 17, 2020 at 16:42
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4$\begingroup$ @jamesqf: I perceive 3 hours London to New York as fast (Concorde). I perceive the same journey by 787 in 6 hours as not so fast. I consider a Piper Cub slow in any configuration - unless it was tied to the back of a Concorde! $\endgroup$ Commented Dec 18, 2020 at 14:23
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5$\begingroup$ @jamesqf: When I'm heading west and the sun is rising in front of me, then that's a very good perception of flying faster. $\endgroup$ Commented Dec 19, 2020 at 18:43
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The Concorde didn’t “refuse” to go supersonic over land; it was legally prohibited from doing so by every country it flew to/over.
The Tu-144 produced the same sonic boom, but aside from a few exhibitions, it flew only to/over countries that had no such law.
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$\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$– FedericoCommented Dec 17, 2020 at 7:51
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Another reason is that much of the flight was over the huge land mass of Kazakhstan with very low population density. So few people live in the steppes there that Roscosmos lets the first stage of rockets taking off of Baikonur simply fall to the ground. You wouldn't want to do that over France or England.1
Population density is higher in Russia close to Moscow, but still lower than in Western Europe, so with a suitable flight corridor most of the flight would be over sparsely populated areas.
1 Bear with me when I divert a little. For details about the first stages falling from the sky in Kazakhstan I recommend the stunning documentary Space Tourists by Christian Frei. One of its threads follows Kazakh metal scrap collectors who hunt them down. You will be surprised what they do with the round bottom part of the fuel tanks on the first evening after finding a stage.
answered Dec 18, 2020 at 8:23
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1$\begingroup$ "You will be surprised what they do with the round bottom part of the fuel tanks on the first evening after finding a stage." This is not a news site trying to get clicks. $\endgroup$– SamCommented Dec 18, 2020 at 13:31
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$\begingroup$ @Sam I am not involved in any way with that movie, if that's what you are implying. Or did you mean I sound like click bait? I just didn't want to give it away. The movie is worth buying or watching if it's still available at all. And while the movie and this detail are off topic on this site, they aren't by much (hey, the first stage is flying, in the atmosphere!). But that's why I put it in a footnote and said "bear with me". $\endgroup$ Commented Dec 18, 2020 at 15:36
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2$\begingroup$ @Sam By the way, do you think this answer has any merit concerning the subject matter? I think it is one main reason -- if Kazakhstan were as densely populated as England or France then even in a Soviet totalitarian regime the plane would not have flown that route (but instead to Irkutsk or some other Siberian place). $\endgroup$ Commented Dec 18, 2020 at 15:51
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3$\begingroup$ @Peter-ReinstateMonica, it's an important distinction that the USSR had lots of sparsely populated land to fly over without bothering too many people. $\endgroup$ Commented Dec 19, 2020 at 17:26
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In addition it's also worth noting that the TU-144 only made 102 commercial flights. It wouldn't really have got to the point where anyone would complain.
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1$\begingroup$ Welcome to Av.SE! Can you provide a link to that statistic? With so few flights, no wonder nobody complained! $\endgroup$– Ralph J ♦Commented Dec 17, 2020 at 23:42
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1$\begingroup$ But the Tu-144 was used by the military until 1999. $\endgroup$– GiovanniCommented Dec 18, 2020 at 8:28
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1$\begingroup$ @Giovanni, western military jets flew supersonic over land regularly, as mentioned in comments to Zeus's answer. $\endgroup$ Commented Dec 19, 2020 at 17:25