Chinese Hypersonic Developments (HGVs/HCMs)
- Thread starter A.Man
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Work on hypersonic vehicles/missiles are already in high gear in China for a long time. Posted by @之尺心亘 on Weibo.
Original post:
Roughly translated:
Original post:
Roughly translated:
China’s hypersonic tungsten rod experiment challenges the US ‘rods from God’ space weapon concept
- A scientific experiment has suggested a kinetic energy space weapon may not work as an effective bunker buster as previously thought
- The idea for a ‘rods from God’ hypersonic weapon was first conceived by the US military during the Cold War
A hypersonic space weapon concept, nicknamed “rods from God”, which was first dreamed up during the Cold War, might not be as effective as previously thought, according to a new study.
The idea for the hypersonic tungsten rod weapon involves dropping a large tungsten rod from a satellite or other spacecraft in orbit. When the rod hits the target at a speed of Mach 10, a tremendous amount of kinetic energy, similar to that of a nuclear weapon, would be released.
When it was first conceptualised, it was thought the weapon would be like a biblical plague raining down destruction from above – hence the term “rods from God”. But although it has been proposed by the US military repeatedly for decades, there is no evidence that any country has developed or deployed such a weapon.
Now, researchers at the North University of China in Taiyuan, Shanxi province, have had surprising results from an experiment they conducted to see what would happen if such a weapon hit a military concrete bunker.
The team, led by mechanical and electrical engineering scientist Fu Jianping with the university’s intelligent weapon research institute, accelerated tungsten rods to extreme velocities up to 3km per second (1.86 miles per second), or nearly nine times the speed of sound.
Tungsten is very dense and hard, and has the highest melting point of all metals. These properties make it an excellent material for use in kinetic energy weapons that kill with velocity and mass.
When a tungsten rod projectile hits a military concrete target at an extremely high speed, it generates a high-pressure shock wave that compresses and heats the target material to very high temperatures and pressures. This causes the target to transition from a solid to a plasma state, where the electrons are stripped from the atoms and the material becomes ionised, according to Fu’s team.
The plasma state of the target material is highly conductive to electrical currents generated by the high-pressure shock wave. These electrical currents can then create a magnetic field that interacts with the plasma, generating a force that accelerates the plasma to even higher velocities.
This accelerated plasma forms a plasma jet that erodes the target material and contributes to the penetration process. However, the plasma jet also interacts with the tungsten rod, causing it to erode due to the high-temperature and high-pressure conditions, according to the experiment.
The remaining mass of the tungsten rod is reduced significantly during the process. At Mach 8, Fu’s team found an entire arms-length rod can vanish almost instantly after impact.
“It is very necessary to study the penetration of tungsten rods into concrete at hypersonic speeds,” Fu and his colleagues wrote in the paper.
“With the development of launch platform technology, the speed of rod-type projectiles is increasing. However, the destructive effects of tungsten rods against concrete vary between hypersonic and conventional speeds. The destructive mechanism also changes accordingly,” the paper said.
“The penetration effect of kinetic energy projectiles on concrete has always been a research focus for a number of countries.”
The university is closely linked to China’s space defence programme, according to openly available information.
During the Cold War, the US Air Force launched a research programme on kinetic bombardment known as Project Thor. The concept was originally developed by Boeing scientist Jerry Pournelle in 1957 and later refined by others, including the Rand Corporation in the 1960s.
The idea was to drop a 6 metre (19.7 feet) tungsten rod from orbit to strike targets on Earth – achieving the force of a nuclear weapon without the radioactive fallout.
In 2003, a United States Air Force report introduced a new system called Hypervelocity Rod Bundles (HRB). This system consisted of tungsten rods that were 6.1 metres long and 0.3 metres in diameter. These rods were intended to be launched from space using a conventional rocket or other launch system, and steered to their target using a variety of guidance systems.
The HRB has the ability to strike targets globally with speeds of around 3km per second at impact. By deploying six to eight satellites on a given orbit, the system could strike a target within 12-15 minutes, according to some calculations. That is less than half the time it takes for an ICBM to reach its target – and without the warning of a launch.
Some researchers said that a large “rod from God” could have the yield of a small tactical nuclear bomb, and they could also be effective against nuclear bunkers.
But these systems were never implemented. One major reason was that the development and deployment of these weapons in space would have required a significant investment of time, money and resources, such as superheavy rockets.
Another factor was the development of other weapons systems, such as precision-guided munitions and cruise missiles, which were seen as more practical and effective for many military applications.
Then there would be political and strategic considerations. A misfire, for instance, could cause a disaster. The deployment of such a system could be seen as provocative or destabilising by other nations.
But China has taken the US military blueprints seriously. In a paper published in 2018, Chinese scientists reported a prototype experiment involving a hypervelocity kinetic energy projectile hitting a ground target in the Gobi Desert.
In the unprecedented experiment, a 140kg (308lbs) tungsten rod was fired at a speed of 4.6km per second by a classified platform from high above the desert, resulting in a parabolic-shaped impact crater with a depth of 3 metres and a diameter of 4.6 metres. The tungsten rod had a diameter of 11cm (4.33 inches) and a length of 84cm. The target area was sand and gravel.
It is possible that this experiment was intended to simulate the effects of a Project Thor or HRB-type weapon, according to some researchers, as the tungsten rod used in the experiment was similar in composition to those proposed for such systems.
But the Gobi experiment raised some questions about the effectiveness of the weapon when being used against a target hidden under the desert.
The data collected by Chinese scientists from the site suggested that the hypervelocity impact cratering effect was similar to that of a shallow-buried underground explosion, and that as the velocity increases, the effect becomes more like that of a surface-contact explosion.
This means that a “rod from God” could have limited ground-penetrating capabilities.
The natural ground in the Gobi Desert is different from reinforced concrete bunkers, which are typically designed to withstand high-velocity impacts and other forms of damage.
In its study, Fu’s team investigated how the depth of penetration of tungsten rods into concrete targets changed with the velocity of the projectile.
The results showed that depth initially increased with the velocity of the projectile, but then decreased after reaching a certain point.
“There is a maximum penetration depth of about 80 times that of the projectile diameter at the speed of 1.2km per second [about 3.5 times the speed of sound],” Fu’s team said.
Pushing the speed higher to hypersonic range, or above Mach 5, would not help the tungsten rod go any deeper into the concrete.
“The penetration depth under ultra-high speed conditions has no advantages over medium and low-speed penetration,” the team said.
At Mach 8, for instance, the entire rod would be turned into a plasma jet on impact, and the jet could only result in a penetration depth of about 50 times that of the rod diameter.
But that is just one of the factors to take into consideration when measuring the destructive power of a kinetic energy weapon such as a tungsten rod.
Other factors include the kinetic energy of the projectile, the velocity of the projectile, the mass of the projectile and the material properties of the target.
Surface explosions can also cause a wide range of damage, including structural damage to buildings and other infrastructure, injuries and fatalities to people and animals, and environmental damage.
Some military scientists say that the development of new launch technologies, such as hypersonic vehicles and rail guns, could increase the potential application of tungsten rods as a kinetic energy weapon.
Rail guns use electromagnetic forces to accelerate projectiles to extremely high velocities and hit targets 200km away at Mach 7.
Meanwhile hypersonic missiles, which can travel at speeds of Mach 5 or higher, provide another possible platform for tungsten rods to be launched from near-space altitudes.
China is the world’s largest producer of tungsten, accounting for over 80 per cent of global production. The second largest producer is Russia.
The United States is a significant consumer of tungsten, but it is not a major producer. The US military is heavily dependent on imports to meet its tungsten needs, with most of its supply coming from China.
By the way, these questions could sound unwise to those knowledgable on the matter here.
Regarding the DF-17 vs LRHW:
1. What are the differences between DF-17 and LRHW, considering that both of them are HGVs?
2. Why does each DF-17 TEL can only launch one DF-17 missile, while each LRHW TEL can launch two LRHW missiles?
3. Why does the DF-17 (1800-2500 kilometers) has lower strike ranges than the LRHW (2700-3000 kilometers), despite being bigger in size (which should carry more fuel)?
Regarding the DF-17 vs LRHW:
1. What are the differences between DF-17 and LRHW, considering that both of them are HGVs?
2. Why does each DF-17 TEL can only launch one DF-17 missile, while each LRHW TEL can launch two LRHW missiles?
3. Why does the DF-17 (1800-2500 kilometers) has lower strike ranges than the LRHW (2700-3000 kilometers), despite being bigger in size (which should carry more fuel)?
DF17 is moving target capable while LRHW isn't. US doesn't have the plasma sheath penetration tech. It's likely that the DF17's target systems and electronics are what mainly make it larger.
Because of that, the max range of DF17 would likely be on moving target, meaning that 2500km might be the hard limit of its guidence systems, while LRHW only needs to worry about fuel.
If the DF17 truly has bigger fuel volume than the LRHW, then I'd bet you can fire them further than the LRHW, but only on stationary, predetermined targets. However, that's just pure speculation since the LRHW isn't close to being finished and I doubt Chinese units will openly talk about how DF17s can be configured. There's also no way to know how much of the DF17's size is due to extra fuel and how much is due to electronics.
DF-17 is a wave raider glider. LRHW is cone shaped glider like DF-21D. For the same intitial velocity and altitude, DF-17's glider should fly much further than LRHW. It should also be able to cover a wider area (maneuverable), meaning LRHW hit a point, DF-17 can hit any point of a larger area.
If we trust wiki, DF-17 is 1.2m in diameter while LRHW is 0.88m. DF-17 is much wider.
The very first question is how and where did this 1800-2500km range come from. Without source from the test shot by PLA, anyone making a claim is just a guessing, My guess can be as good as US intellegent analyst.
The possible reason (if the range figure is to believe) is within your question (bold texts). The mass of the warhead (glider) is a dead weight, the heavier it is, the smaller the 1st stage is relative to the lauch mass. So the larger the warhead, the slower and shorter the acceleration, the lower initial altitude and velocity of the gliding phase, the shorter the range is. It is a trading between destruction power and range.
I suspect that your question regarding range stems from thinking the warheads have their own engine and fuels. No, none of DF-17 nor LRHW's glider carries fuel. Only their first stage carry fuel (SRBs). The range is determined by the size and burntime of their first stage.
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1: LRHW is not really a HGV in the conventional sense as you would expect with the standard aethestics being extremely thin and flat. The C-HGB is, if anything, more comparable to a more maneuverable Pershing II with its conical glide body. More resembling a MaRV not a waverider. So not really comparable per se as they possibly ( and highly probable that) fly different trajectories.
2: LRHW is, IIRC, supposed to be installed on DDGX and backfitted VPM modules. Apparently the IR-CPS cells on VPM modules are somewhere below 29 inches/0.74m in diameter while the DF-17 is approx 1m. So LRHW being the ground version of CPS would be similar in dimensions, and thus would be smaller than a DF-17 round-for-round.
3: Would require OPSEC breach, though I'm suggesting:
+ Maybe the DF-ZF has less advanced electronics so it requires fitting more?
+ More protective covering/ballast.
+ Provisions for a large anti-structure warhead. Given the sheer size of the DF-ZF glide vehicle I'm imagining it not as a precision ship killer but some sort of Guam killer.
+ Less advanced propulsion tech. Assuming the figures you quoted is decent enough to run assumptions on, it's not unreasonable to assume that the DF-17 use a less effective propulsion than the LRHW. After all PrSM is hitting in excess of 499km ( and might as well be far more than that) and is peaking solid fuel rocket right now and with ramjets can hit MRBM territory. US propulsion is still something else, so a certain possibility eh?
I recall seeing a graph somewhere on the forum, which plots speed versus distance for a hypersonic glide vehicle.
Also, if you look at it from a requirements perspective, all of Japan, Korea and Taiwan is within 1400km of mainland China.
Then the next potential target is Guam in the Second Island Chain, which would require a 3500-4000km ranges missile.
So why would the Chinese military overengineer A DF-17 HGV for a range of 3000km? Better to put a heavier payload in the and accept a 2000km range instead for example
The graph is probably from me which I got from a Chinese book.
In this book it presented calculations based on certain parameters of rocket stage, heat load, max altitudes. It presented three conclusions, ranges are from >5000km, >8000km and >12000km. For the 5000km study, the shortest range is 1800km, the shortest range gives the largest side range. If the missile is to reach the furthest range 5000km, it can not maneuver, it has to travel a straight line.It is all about energy, the 5000km max range and 1800km shortest range have the same energy. Now when somebody says DF-17's range being 1800-2500km, what exactly that means? If 1800 is the minimum, the maximum should be over 5000km according to the study. Just by looking at the 1800-2500 figure, I highly doubt whoever put up these numbers know what he was talking about.
A 5000km max range is NOT over engineering, it's true intended target is somewhere within 4000km. The "extra" energy is for evading interception (for both fixed and moving target) or chasing moving target. I am sure LRHW's "extrodinary" range is the maximum range, but as it is much less maneuverable, it's minimum range is much higher therefor giving an impressive number, but it is really a disadvantage instead of being proud of. But if people really want to compete for useless straight line race, DF-17 is probably able to go as far as LRHW.
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