China Purchases Russian Radars
In 2004 China bought Russian Podsolnikh-E high-frequency (HF) surface-wave radars for coastal surveillance. These radars use the ionosphere and the conducting surface of the sea as reflectors to form the boundaries of a waveguide. They reach beyond the usual radar horizon, which is four-thirds of the visual horizon. What is special about HF radar is that the wavelength is so long (typically 10 to 150 meters) that it is not greatly affected by the shape of the object it encounters. Stealth shaping would have little or no effect on detection. Maximum range against surface targets, set by the nature of HF propagation, is generally given as 180 nautical miles, and against air targets as 250 nautical miles. Podsolnikh uses two separate antenna fields 500 to 3,500 meters apart, each 100 meters wide, one to transmit and one to receive.
An HF radar cannot support a direct attack against a stealthy surface ship on its own. Because the radar has a very long wave-length, it has limited precision. The Russians claim that the simplest version of their radar will determine target range and bearing within 1 kilometer and 1 degree, respectively. Because the radar detects by Doppler, it also directly measures target speed (to within two kilometers per hour or about one knot). A missile fired on the basis of this sort of data would still have to search for its target, and the target's stealthy design would probably be far more effective against the missile's short-wave seeker. However, the missile would know that the target was within a box of limited size, perhaps 1,600 by 5,000 feet. Stealth would reduce target radar cross-section to the level of random noise. A missile could compare the apparent motions of all radar returns above a minimum size, and sift out those that did not behave like ships. That might be enough for it to determine the ship's location.
Alternatively, a group of missiles or aircraft might compare their radar images (the Russians have long had a missile-to-missile link, admittedly carrying very little data, in their SS-N-19, and they offer one in the current Yakhont). Netted radar sensing can reveal stealthy aircraft, largely because few if any objects are stealthy in all aspects. A moving surface vessel has the additional disadvantage that it trails an easily detected wake. Stealth might still retain value, in that a ship with a small enough radar cross-section could be confused with a decoy moving realistically. Since decoys are relatively large, the required degree of stealth might be dramatically less than that represented by a ship such as DD(X). However, such a ship would probably still be vulnerable to infra-red (IR)- or electro-optically guided weapons, which are much more difficult to decoy.
Anti-radar stealth is quite expensive. To reduce radar cross section dramatically, the ship or airplane must be shaped very carefully. Defects in surface shape must be eliminated both during construction and in service. Construction demands a degree of precision unknown in the past, and is far more expensive. Shape must be maintained within a fraction of a wavelength, and the target radar probably operates at about one centimeter wavelength or below. Maintaining a precise shape in service is even more difficult. The need to maintain a precise shape explains why, at least at first, the B-2 bomber was not considered effectively stealthy in rain (droplets forming on it would destroy its stealthy shape). For a ship battered by the sea, that means much heavier hull plating. It may also be necessary for the hull to always present itself at the same draft and even at the same trim and without noticeable roll. This sort of performance requires ballast tanks to compensate as loads are consumed, so that the waterline never changes. The ship may retain much less reserve buoyancy than would be normal for her size, with consequent limits on her ability to absorb damage. To a considerable extent, from a design point of view, the surface ship, which in the past always benefited from very flexible design constraints, comes to resemble a submarine, with very limited internal space compared to her displacement. These factors may help to explain why DD(X) is such a massive ship.
Until the advent of HF surface wave radars, U.S. ships could consider themselves largely invisible to foreign countries as soon as they disappeared beyond the coastal radar horizon. With the very important exception of ducting situations, such radars see no more than 20 to 40 miles out to sea. With its long-range guns, DD(X) might be able to fire from outside solid surveillance range. At the least, it could expect to approach a potentially hostile coast undetected. This potential justified a very heavy investment in stealth.
Now that the Chinese appear to be buying a specifically counter-stealth long-range radar, the value of that investment may be compromised. They could provide North Korea either with HF radars or with the fruits of Chinese HF radar surveillance of Korean waters. In the latter case the United States would not have the option of opening hostilities by destroying the offending radars, as it did so successfully in Iraq. Given the Chinese example, the Russians will probably sell HF radars to countries that may feel vulnerable to U.S. attack. The radars themselves provide no insurance, but they do bring into question the value of extreme stealth measures in those ships used to attack surface targets.
As for missiles, the advent of such radars suggests that current subsonic stealthy missiles, such as the Tomahawk, may be less useful in the future. Instead, the future could belong to ballistic or semi-ballistic weapons that spend most of their time outside the surveillance volumes of HF radars. Alternatively, U.S. forces may have to launch at much greater ranges simply to allow at least the initial missiles to fly outside HF radar coverage (HF radar sites should be easy to spot). None of this takes into account the new passive radar technology, which promises detection of many stealthy air vehicles flying over relatively populous areas.
Varyag Redux?
Speculation is increasing about the former Russian carrier Varyag, which Ukraine sold to the Chinese in 2000. At the time, the ship was described as a leaking hulk, purchased for conversion into a casino in Macao. Nothing came of the conversion plan, and the casino story may have been a ruse. The carrier, now painted in standard Chinese naval colors, is at a yard at Dalian, where a new Chinese missile destroyer (pennant 115) is being completed. Like several Chinese shipyards, this one handles both commercial and military work, so the presence of the ship does not prove very much.
The main question is: Just how complete or incomplete was the ship when she left Ukraine? At the time, published satellite photographs showed material for the ship piled on the adjacent pier. Varyag was never fitted with her radars, and the material on the pier probably included a good deal of her electronics. At the time, Soviet-era shipyards were being plundered for valuable materials, which would presumably include the wiring and piping of a modern warship. On the other hand, it is not clear whether material deep in the ship had been removed. Engines and boilers, installed prior to launch, would need to be taken out through the deck, and photographs did not show any large holes in the ship. Clearly they were not operational when the ship was towed to China, but that may have been because the necessary electronics either had not been installed or had been stolen. This equipment could be easily replaced.
There are, however, obstacles to restoring derelict vessels to operational status. A ship lying incomplete for a decade or more deteriorates. The insulation on wiring can rot, particularly in a hot climate. Even main propulsion machinery can be damaged (ships lying in reserve in the United States had their engines and propellers turned over regularly so they would not get out of true). There is no evidence that much effort was made to preserve Varyag after construction was canceled. The Ukrainians did have hopes of selling the ship for completion. Such hopes would have encouraged them to make minimal preservation efforts. Buying the ship as a casino would have been a canny way to circumvent any Ukrainian attempt to have the Chinese pay for completion in the yard that had built the ship, and also to force her sale price down to something like scrap value.
For years reports surfaced that the Chinese had shown intense interest in the ship, that they had invited her designers for consultation, and they had bought her plans. A recent Russian article refers to Varyag as a future Chinese carrier target, to be used either to train Chinese naval aviators or to test anti-carrier tactics. The article assumes that the ship cannot possibly be made operational, but it is not clear why that should be so. Completion would involve installing the heavy self-defense battery planned, and also the surface-to-surface missile battery (SSN-19s). Western carriers operate effectively without equivalent weapons. The Chinese might well be willing to forego them, in which case the ship may be much closer to usable than her designers suppose. Are we about to see a radical shift in the Chinese Navy?