The hypersonic speed is triggered as soon as the booster stage is released and the scramjet starts working to achieve those speeds. I believe the Russians know that the determining factor of Tsirkon is not its description of avoiding detection by enemy systems, but its speed. Hypersonic speed means it must fly relatively high, which means it must be able to be detected at long range, but the high speed will reduce the available reaction time and, of course, the maneuverability would make it a desperately difficult target to be engaged.
Traveling at high altitudes is not a problem because the very high speed means that although the air may be cooler and thinner, the volume of air collected is huge simply because of the flight speed, so it's okay to use a scramjet engine. In reality, the scramjet engine works best at high altitude, so staying at high altitude and diving to land on the target can be a useful concept. Tsirkon will fly at mach 8 only at high altitudes. At high altitudes the air is less dense compared to lower altitudes. The heat accumulated due to friction with the air will be less at these higher altitudes, at which altitude the scramjet will work best, so the Zircon would hardly perform any flight course action at low altitude.
Plasma is created around mach 6 and becomes increasingly detrimental to radio communications thereafter. On mach 8, signals such as GPS reception will be seriously affected.
As for temperature, hypersonic velocities generally generate boundary-layer temperatures of 1000°C or more, enough temperature to saturate the IR sensors, that in itself is not a problem, the Tsirkon probably at terminal velocity, will have speeds at mach 6, SAM missiles like the Russian 48N6 has 6.2 mach speed and even features a semi-active nose radar.
Going back to the IR sensors issue, behind a nose blinded by the plasma, the Tsirkon missile may have forward-facing side IR sensors that it might be able to look even under the plasma. In addition, a normal old technology cooled thermal imager has its elements cooled with liquid nitrogen, cooling the surface of the missile. To overcome the problem of generated heat, Tsirkon can easily have ablative materials near the hot spots (nose) and even pump its liquid fuel through the surface of the skin where heating occurs to prepare the fuel and cool the surface.
Regarding the search for the target, it all comes down to how much the target moves and how accurately the target is located in the first place, it is worth noting that the missile flying at mach 6, will reach the target in less than 7 minutes at 500 km from range, compared to the target ship, it will travel a much shorter distance in any direction, leaving a much smaller target area for the missile to search for the target. Just noting that most ballistic targets when performing the maneuver reduces speed, but for Tsirkon which is a powered missile, then it won't lose as much speed during turns, and can regain lost speed, in the matter facing Tsirkon, slow down speeds before hitting targets is due to target acquisition, last stage tracking, with the scramjet engine burning all the time means more energy and the ability to maneuver without necessarily losing speed.
This was probably already beaten to death by other two users which I dont know if you came across yet but the agreement I can see on both sides is that speed and based on what altitudes are cruised at(no idea how long zircon is staying in 40kms altitude throughout its flight) plasma forms which effects radio frequencies based on their wavelengths. -10 or -15 decibels or whatever it was, was the effects of dropping spheres from space according to a NASA research paper. But what we or what I dont know is would scramjets have more favorable plasma conditions because I take it that spheres have a creeping wave return while I think scramjets dont suffer from such effects from radars. And the obvious no shit example of scramjets besides being hypersonic is the advantage of lower altitudes over ballistic missiles.
Also the communcation part with the missile was already beaten to death here as well.
https://www.technologyreview.com/20...black-out-problem-for-re-entering-spacecraft/
What you said is true, it just confirms what I said.
Let me clear the whole thing about missile communication. The Russians weren't the first to create a kind of communication with the spacecraft reentering the atmosphere, it was NASA. Until the entry of the "Tracking and Data Relay Satellite System" (TDRSS), upon re-entry into the atmosphere, the space shuttle suffered a blackout preventing it from communicating with ground stations, although this gap without communication depended on many things such as the shape of the shuttle space, the angle of reentry, speed and other things, the fact is that all space shuttles suffered the blackout, some for 9 minutes, others for 30 minutes and depending on the conditions previously reported. That ended with the introduction of TDRSS.
The TDRSS allowed the shuttle to communicate by relay via data relay satellites during re-entry, through a hole in the ionized layer at the end of the shuttle's tail, created by the shape of the spacecraft. NASA and China National Space Administration have data relay satellites (for NASA this is TDRSS), which allow tracking and communication during the blackout, basically, the rear end of the re-entry vehicle is not obstructed by plasma.
Because of the shape of a warhead when it reenters the atmosphere, the rear end will likely not be obstructed by the plasma, and thus, at the rear, the temperature would be thousands of times lower, so the only place that can receive a data relay sits in the The same way the space shuttle communicates with the TDRSS during re-entry, I think the Chinese did it with the DF-21D.
Three (plus) spacecraft circling 22,000 miles overhead are better than dozens on the ground.
www.airspacemag.com
In other words, communication during reentry even under plasma has been resolved since the 1990s, I'm sure many studies have been done to get around this, the plasma problem being much more significant for reentry vehicles or warheads than for objects that remain in the atmosphere continuously, but the plasma problem still manifests itself.
My problem with these missiles is a Yasen-M(also how stealth are they from SONAR arrays placed on coasts) getting close to our coast and launching an entire barage of them. it will take awhile to get infrared satellites or ground radars to cue the attack is coming to respond effectively with interception methods in which I think it is already too late when a nuclear warhead is flying low above our heads and if detonation occurs all electronics in close proximity are screwed and when it occurs it will cause major radar blind spots depending how fast the frequencies disapate where another barrage of missiles pass through the radar blind spots masking themselves from radars further away targetting them creating a domino effect entering the mainland deeper and deeper assuming they are all getting intercepted while the detonations occur until we are stone age and not browsing secretprojects anymore.
The scramjet works best at high altitudes, some sources indicate the altitude is 40 km, another 30 km, however, I see that at some point in the missile's flight course, it could be operating at 50 km altitude.
The issue of IR tracking of the Tsirkon by the Americans through satellites is not unfeasible, this is because the Tsirkon would have a very significant increase in its IR signature, even at low altitudes, it would hardly go unnoticed by the Americans. On top of that, LM is ready to deploy another IR surveillance satellite, improving surveillance against ballistic and hypersonic missiles:
https://www.electronicsweekly.com/news/lockheed-martin-completes-sbirs-geo-6-missile- warning-satellite-2021-10/
