‘Supersonic’ subs – reality, pipedream or propaganda ?
A flight of fancy !
by Robert Whiston FRSA Sept 2014
Some thoughtful soul, possibly from the Tampa Bay Enquirer (or Reuters) posted news on the “Torpedo Technology”  blog page of an allegedly ‘super-sonic’ submarine. Allegedly, a Chinese professor at a China based institute had claimed that it was theoretically super-sonic submarine travel was possible and that they had it under development.
This happened a few days ago and so it has been able to scan other news sources and the ‘Harbin Institute of Technology’ (the originator of the claim), is not a name that leaps immediately to mind
Coverage of the claim has met with serious doubts and reservations, if only because the physics are almost insurmountable at present. Eradicating bow waves have always posed problems for submarine designers and the management of water flow around submarines is a science unto itself.
On a conventional submarine layout (see the profile below), the water flow first has to meet the bow, then the conning tower (fin) before finally hitting the turbulence aft and the screw (or screws, aka the propeller).
The new technology that Harbin Institute scientists claim to have developed is comparable to, if not based on, the technique deployed on the Russian “Shakval” torpedo of the 1980s (with an estimated speed of 200 – 370 mph). In their proposed submarine it also shrouds itself in air bubbles to reduce the friction and resistance of water. The downside of the “Shakval” torpedo is that it reputedly travels only, or at best, in a straight line and might only have a range of only 4 – 8 miles. Will these limitations dog Chinese efforts ?
Far fetched ?
Apparently, after reaching a speed of 47 mph or more, the vessel could enter the ‘supercavitation’ high speed state and could theoretically travel up to 3,600 mph while underwater.  This would be made possible by a man-made liquid membrane on or over the vessel surface which would help steer as nozzle directional controls create different levels of friction on areas of the submarine to create turns.
It this is a rather contradictory or opaque explanation, Li Fengchen, professor of fluid machinery and engineering explained that:
- “Our method is different from any other approach, such as vector propulsion, or thrust created by an engine. By combining liquid-membrane technology with supercavitation, we can significantly reduce the launch challenges and make cruising control easier.”
One suspects that the supersonic submarine would, like the Shakval torpedo, fly in its own gas bubble created through “supercavitation. Critics have pointed out that a rudder would be useless on a Shakval torpedo, (being inside the water-free bubble), and any wire guidance system would be suspect or unreliable.
However, a cross-section of the torpedo does indicate ‘cavity piercing’ fins for steering “the missile” (see right). And in common with the proposed Chinese submarine, a rocket propellant is being considered as the motive force and at 3,000 MPH that too must be considered more of a missile than a ship.
While artist impressions are just that and can therefore be very misleading, the depiction of the proposed Chinese submarine (shown below) appears to have a supercavitation envelope extending well to the stern of the projectile.
Prof Li acknowledged that there are many technical problems that needed to be solved before supersonic submarine travel could become feasible. Not least of which is the control issue (with the need of a redundant system always to be on hand).
At present a ground-to-air missile has a disproportionately large propellant tank and one can only imagine the size of both the propellant motor and the fuel tank required for a submarine to cut through the denser water. Even if the water density is reduced by bubbles and polymers, if the large distances envisaged are to be travelled, this will raise other considerations. We have no idea how these bubbles will be manufactured by the craft as its spans the great oceans but one can imagine a massive amount of air will be used up and that air cylinders or air generation equipment will eat into cargo space unless a regime of air bubble manufacture using something like hydrogen extraction from water is utilised.
The Concorde experience
When supersonic air travel became a reality with the Anglo-French Concorde it came at the price of many things including flying blind at mach 2, drag, blind landings and air fame expansion and contraction.
For supersonic travel nose cone shapes needed to be aerodynamic as shown in the following pictures of two prototypes. However, it was not long before a mechanical nose droop and nose up option was chosen as the best synthesis. This resulted in the very distinctive Concorde nose.
Pictures courtesy of “Heritage Concorde” (http://heritageconcorde.com/technical-2/nose-visor).
Similarly pioneering problem will attach to submarines travelling at very high speeds. It will need to see where it is going and needs to be able to avoid not bird strikes but underwater strikes with sunken wrecks, mountainous regions, fish and large sea mammals.
The news of this startling maritime proposal comes against a background of China continuing to fall out and bully her immediate neighbours. It’s quite likely this ‘super-sonic’ news has more to do with intimidation than any practical application and follows hard on the heels of the contradiction in China’s avowed ‘friendship’ foreign policy agenda.
All this blustering, posturing and serious threatening by China has involved territorial water disputes with its immediate neighbours. Of course, under those waters lie the gas and oil reserves China desperately needs and which were highlighted by this author some years ago (see “Shi Lang’ – a new page opens”, 2011).
China does not want to be ‘import dependent’ like her immediate and economically more advanced neighbour, and arch rival, Japan
China and the CPC (Communist Party of China), have long attached great importance its ‘friendship’ stance of being a good neighbour, of being helpful and friendly to all in the China Sea area. As recently as Aug 25th 2014 Beijing restated the country’s policy is to help its neighbours prosper and according to the Communist Party of China seek peaceful coexistence with all. 
China is quick to point out its peaceful co-existence, principle with neighbours like India and Nepal yet rides roughshod over, say, Vietnam or Tibet, the latter of which never wanted China’s invasion in 1950 – though in true Marxist style the Chinese see it as ‘a war of liberation’ – and later (in 2006) its direct railway connection. In between such dates The Dali Lama became and remained a hunted man.
With an eye to history, China’s policy to work in cooperation and help its neighbours prosper. Her plans to aid them grow economically (e.g. Fiji, Tibet, Taiwan, India, Pakistan), also involves their growing away from their traditional allies and source of support i.e. the West, usually in the form of the US or Europe.
All this rather smacks of Japan’s infamous “Greater East Asia Co-Prosperity Sphere” of the 1930s which actually replaced one colonial landlord with another and had nothing to do will liberation, self-determination or democratisation or economic greatness (except for Japan).
So China’s claim to islands in the China Sea, driven not by integrity by a lust for oil, and its laissez-faire approach to investment in Africa and African governments (which are some of the cruelest), rings hollow.
Since the 1980s we have seen China blackmail dozens of countries into not trading with Taiwan (they found it almost impossible to get submarine replacement for its World War 2 Guppy’s). This precedent of letting the Chinese government find its feet so it could join the ranks of the international community and begin to act sensibly, has backfired as can be seen in its heavy-handed approach to its near neighbours like the Philippines and Vietnam.
However, bullying tactics are not confined to small states but has drawn in larger countries like Australia which publicly “chastised” Taiwan (with an Aussie trade deal in the offing?) for continuing to push for its independence. 
The crushing of HK
And even closer to home, Hong Kong is another case of, “We told you so.” Many of us can recall the unbridled enthusiasm for a ‘One China’, exhibited by our Chinese colleagues at the prospect of Hong Kong being handed back to China – and their even greater delight on the day it happened. They totally overlook the inept way the PLA entered HK and took control with poor taste and a bad grace. This was all the more magnified by the unruffled, dignified lowering of the colours in what was a seemingly effortless British ceremony in HK harbour economising the respect for the individual and of promises made.
Over the subsequent years Hong Kong has endured a series of snubs and Peking directives with the latest one (Aug 2014) being the reneging of a promise to Hong Kong that it could pick its own political leaders. Hong Kong’s dram of a democracy while remaining within China, is now finally crushed.
Until more is known this idea is just that; an idea, and this flight of fancy should be binned in the ‘science fiction’ category until we hear to the contrary.
E N D
 See ‘Chinese Military Claims to Design First Supersonic Submarine’ http://news.bestoftampabay.com/chinese-military-claims-to-design-first-supersonic-submarine/
 See “Neighbours high on China’s foreign policy agenda”. http://www.ekantipur.com/2014/08/25/top-story/neighbours-high-on-chinas-foreign-policy-agenda/394053.html
 See ‘Aussie-Chinese poker game’ http://www.australianbusinessjournal.com.au/aussie-chinese-poker-game/