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CONCEPTS IN SUBMARINE DESIGN PDF

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ppti.info - Ebook download as PDF File .pdf) or read book online. concepts in submarine design. 1 - Design in general. pp · ppti.info Access. PDF; Export citation. 2 - Milestones in submarine history. pp Cambridge Ocean Technology Series: Concepts in Submarine Design Series Number 2 by Roy Burcher, , available at Book Depository with.


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Read Online Concepts in Submarine Design (Cambridge Ocean Te pdf look for book, may be the book untitled Concepts in Submarine Design (Cambridge. If you may be interested to read this Concepts In Submarine Design publication of You will likewise find this electronic book in style ppt, pdf, txt, kindle. Concepts in submarine shape design. *Mohammad Moonesun1,2, Asghar Mahdian3, Yuri Mikhailovich Korol1,. Mehdi Dadkhah2, Mehrshad Moshref Javadi2.

However, usable volume is very limited, since the strength of the sphere decreases as it is made larger. Su bmarine designers tend instead to use stiffened cylinders, which are the most practical compromise between weight, streng1h, and arrangement.

They may be externally framed to limit losses of precious internal volume , with hemipherical caps at the ends.

Frequently bought together

Despite its cost in volume, internal framing has important dvantages. Water pressure tends to press the skin of the pressure hull into the frame. By contrast, it tends to tear the skin away from external frames.

Their welds, moreover, are more vulnerable to stress-enhanced corrosion. Truncated cones are sometimes used as a concession to overall hull shape, to improve hydrodynamics. Several World War II submarine designs had non-cylindrical end ections. These were accepted to gain pace for more torpedo tubes, at a considerable cost in structural complexity or, perhaps, weakness.

Some British submarines had non-reloadable bow tubes external to the pressure hull, a compromise which made for a powerful initial torpedo salvo without requiring a weakening of the pressure hull. For any cylindrical pressure hull, strength declines as diameter increases; deeper diving requires either a narrower or thicker hence heavier pressure hull or a new hull material.

There are several American example. The nuclear attack boat Narwhal built apparently required considerably increased diameter to take a carefully silenced power plant.

The subsequent Los Angeles and Ohio classes required more space to fit more powerful reactors. It is not clear to what extent diving depth limitations had to be accepted in any of these cases; the alternative would have been increased hull strength bought with thicker plating or frames brought closer together, both of which add weight. The other major limitation on diving depth is the streng1h of the many connections at which the pressure hull is penetrated; examples include the propeller shafts, the periscopes, and the seawater inlets of a nuclear submarine.

As ubmarines dive deeper, it becomes harder to maintain absolute watertightness III these hull penetrations. A circular cross-section is an awkward space, relatively difficult to use fully. One early twentieth century designer, the Italian Laurenti, tried to use elliptical pressure hulls, but he was defeated because he could not achieve sufficient streng1h on the available weight. His successors tried multiple cylinders instead, to gain internal volume without excessive length. The first such submarines to be built came in , the German Type XXI and the Japanese J; the former with a figure-8 and the latter with side-byside cylinders.

In the Type XXI, the extra volume was used to gain volume for extra batteries; in more conventional submarines, The US submarine was typical of single-hUll craft of her period.

She is shown in drydock at Portsmouth Navy Yard. New Hampshire. The entire circular-section hull shown is the pressure hull.

Her starboard forward diving plane can be seen folded back against the casing. There were no stern tubes.

US Navy the batterie were stowed below the deck in the space remaining within the usual cylinder. At about the same time the Dutch naval constructor M F Gunning in Britain uggested a triple-hulled cargo submarine, the hulls forming the apexes of a triangle; po twar his ideas were applied to several Dutch attack submarines. The new Soviet Typhoon class missile submarine appears to employ a pair of side-by-side pres ure hulls, with missile tubes between them.

Pre umably the Soviet were unable or unwilling to build a single circular-section hull of sufficient diameter to accommodate these missiles more conventionally.

Alternatively, they may have wanted to continue to use the industrial plant built up to construct pressure hulls for the 'Yankee' and 'Delta' classes. In the Typhoon, the elliptical cross-section is formed by fairing the gaps between the two cylinders. A truly elliptical hull would be far too weak to be worthwhile. The circularsection interioJ is the pressure hull proper.

The big external tanks. Two circular frames are visible inside the pressure hull itself: the braces will be removed as the submarine is fitted out. This photograph was taken at Manitowoc Shipyards on Lake Michigan. As a result, the US Navy decided to build a small submarine for experimental purposes prior to introducing the new HYI30 steel in full-size submarines.

A imple change in hull material can have a dramatic effect on diving performance. The United States entered World War II with submarines built of mild steel, rated to dive routinely to about ft, ie with a collapse depth of about ft.

They also expected to introduce a new high tensile steel HTS that would bring collapse depth to ft. Operating depth was therefore set at ft in the new submarines. But none ofthe essential machinery, such as the trim pump, had been tested at the greater depth, and the new submarines were rated only at ft.

In practice, this sufficed, as the new HTS was 20 downgraded due to wartime shortages, and the calculation were therefore overoptimistic. Given a fixed demand for internal deck space, the submarine designer can choose from a variety of external hull forms. A submarine intended for high surface speed has to be relatively long, for a favourable peedlength ratio. This requirement wa, if anything, exaggerated by the scarcity of internal volume for diesel engines for surface propulsion.

Until after , then, submarines were build on a single principal deck level, with batteries relatively heavy below it; and the principal compartments distributed along the boat's length, namely torpedo rooms fore and aft in some boats , limited berthing, a control room, and engine spaces. Underwater, by contrast, for a given hull form, drag is proportional to the surface area of the submarine.

A long hull has a relatively high ratio of surface area to volume, and in any ca e reductions in volume di placement reduce surface area as well. However, note that in the case of the current Los Angeles cla s, increased power was equated to much longer machinery spaces, hence to greater overall length. Note that outside the engine and reactor room the key requirement for internal space is for deck space with adequate headroom , not for volume per e.

Smaller hulls could be wrapped around the same deck area, if it was arranged differently. For example, Skipjack, launched in , was the first US submarine with four deck levels. She had about the arne total deck area as the three-level Nautilus, but much reduced total pressure hull volume, for a noticeable saving in di placement, and also in hull urface area, hence drag. Given a fixed hull volume, appendages such as the fixed sail and the diving planes contribute heavily to hull drag, and advocates of high underwater speed have proposed that the sail be eliminated altogether.

For example, the Thresher class hull was much larger than that of the earlier Skipjack largely to fit a new bow sonar and a much quieter hence more voluminous powerplant. Their cost in speed was to be held to a minimum. The designers could not increase power, as it would have taken far too long to design an entirely new reactor.

The only choice was to minimise the increase in drag, and that was achieved in part by cutting down the sail structure and the masts it contained. An example will illustrate the lengths to which the designers were prepared to go, although it should be noted that a proposal to eliminate the sail altogether was rejected.

In the Skipjack class the superstructure other than the sail had been reduced to a spine which covered the intake and exhaust piping of the emergency diesel engine, housed in the engine room and connected to a snorkel in the sail. That spine had to be dispensed with, but there was no space within the hull to pass the piping through. The solution was drastic. The emergency diesel was moved out of the engine room, and placed in a separate space almost directly under the snorkel in the sail, which itself was drastically reduced in size.

Some speed had nevertheless to be acrificed, but not nearly as much as would have been the case had earlier design practices been continued. Ironically, within a few years the Thresher design had to be modified to increase the number of masts and the height of the sail, apparently for near-surface performance, and speed had to be sacrificed anyway.

It seems likely that the sacrifice wa limited by the careful hydrodynamic design of the original Thresher. Submarine evolution can be read in part as a balance between surfaced, ubmerged, and diving characteristic.

That is, until , surfaced performance equated to strategic mobility, while submerged performance counted primarily at the point of attack. The higher the surfaced speed, the better the chance a submarine had of closing with highspeed urface targets, and also the faster its transit to the war patrol areas. World War I experience, particularly in the German avy, showed how much more important surfaced speed was, and the US Navy actually redesigned its submarines for better surface performance at the expense of underwater speed.

For example, the American'S' class was designed with carefully streamlined bridges and fairwaters, and with deck guns able to retract for minimum underwater resistance.

However, in response to war experience they were redesigned with larger, drier bridges, and with more powerful deck gun. At the same time surface safety features such as permanent life rails and wood decks were added.

The total cost of the change in emphasis was about 3 knots in underwater peed. The other great issue in surface performance is reserve buoyancy, essentially the volume of the tanks the submarine floods to submerge.

In the US Navy, for instance, the evolution from coastal defence to seagoing submarines was measured in part in the increase in reserve buoyancy from 12 per cent in the original Holland of to 13, 16, and 19 per cent in the later 'D' , 'E' , and 'F' classes, the latter capable of going about miles out to sea.

Even then there were problems. Most of the reserve buoyancy was amidships, so that boats tended to nose under in head ea rather than rising to them. Aft, propellers and diving planes were too near the surface, coming out f the water too easily in rough weather. This issue is somewhat clouded by the practice of providing submarines with freeflooding superstructures for better seakeeping.

Some early de igners, such as the merican Simon Lake, made their casings watertight, controlling their flooding. Such designs were relatively complex, and made for slow diving. However, a fully freeflooding casing could flood in a heavy sea, and make a submarine bow-heavy. The typical olution was to provide buoyancy tanks forward, watertight except for flooding holes; they improved surface performance, and could be flooded on diving.

The three basic submarine hull forms, single-hull, double-hull, and the intermediate or saddle tank, are alternative approaches to the surface v submerged problem.

A classic single-hull submarine carries all of its tankage inside the pressure hull. In consequence it is the simplest to build, at least in small sizes, and it has the least hull surface area, for minimum underwater resistance. However, that internal tankage detracts from the limited internal volume of the submarine. The greater the reserve buoyancy required for surface cruising, the worse the problem. In modern single-hull su bmarines, moreover, considerable internal space is lost to reinforcing frames, which can be external hence inexpensive in pace terms in doublehulled craft.

John P Holland's early submarines were intended primarily to operate submerged, for coastal defence, and so emphasised underwater performance; they had single hulls. The US Navy, for example, abandoned the single hull during World War I in order to achieve greater urface reserve buoyancy, and did not return to it until the era of the 'true submersible' nuclear submarines. Most Western submarine designs are described as single-hulled, but they differ from their classic ancestors in that all of their main ballast tanks are outside the pressure hull.

Instead, they occupy portions of the streamlined hull fore and aft of the pressure hull. Many of the earlier single-hull ubmarines had some of their ballast fore and aft, but they also had internal ballast tanks. Probably the earlie t all-external single hull class was the German Type XXIII coastal submarine of ; internal space was at a premium due to its unusually large battery capacity. Double hulls were introduced in by a French designer, Maxime Laubeuf, who advocated 'submersibles', ships which would spend most of their time on the surface, diving only in the presence of their targets.

His approach was to superimpo e a floodable ship hull, adapted from contemporary torpedo boat practice, atop a submarine-type pressure hull. To keep this casing well out of the water, he had to provide substantial reserve buoyancy in the form of floodable saddle tanks between pressure hull and casing. By contrast, the French in particular commonly referred to single-hull boats as submarines, ie as craft uitable only for submerged operation.

Cambridge Ocean Technology Series: Concepts in Submarine Design Series Number 2

For example, the earlie t French undersea craft were propelled only by batteries, and they were intended to operate underwater almost all of the time. She was complete except for her casing and her conning tower.

The framing visible amidships belonged to the pressure hUll. The bow was complete because it contained the buoyancy tank. The Electric Boat house flag flies from the stub that would have led into the conning tower. Walrus was delivered incomplete. The double hull, then, was associated with surface performance and with fuel capacity.

Roy Burcher, Louis Rydill. Concepts in submarine design

Submarines typically had only a 6 to 10 per cent reserve buoyancy, compared to as much as 30 to 40 per cent in a submersible, in which a ship-like outer hull surrounded the pre ure hull.

The ubmersible was much more seaworthy, with its substantial freeboard, and could attain higher speeds on the surface, due to its finer hull form. It was also much safer on the urface, due to its greater transverse and longitudinal tability from its greater waterplane area. The space between the two hulls was generally u ed for ballast, but it could also stow fuel oil, for greater range. External ballast tankage could even be used for stowage of weapon in pressure-proof containers.

Finally, framing between the two hulls could increase pressure hull trength without any co t in valuable internal space. On the other hand, all of that superstructure had to be flooded a the submarine dived. US Navy although war experience soon changed that.

The Royal Navy came to the double hull via an intermediate step, the saddle tank, in which external tanks were built around the pressure hull. In the 'D' class approved in reserve buoyancy was gained by carrying most of the balla t water externally, although some internal tanks were retained.

The extra internal space made for much better habitability rather than for extra fuel for greater range , since the earlier singlehull 'C' class already had a theoretical radius of action beyond the endurance of the crew. The saddle tanks al 0 greatly increased waterplane area, hence longitudinal and transverse stability on the surface. At this time the French and Italian navies were already using more or less completely double-hulled submarines.

British constructors rejected them for the time as too complex, with unduly bulky ballast piping. However, by many British officers felt that the double hull might be worth testing, and in February a Submarine Committee called for both overseas and coastal submarines of double-hull design. Only later would it become clear that small double-hull submarines were inefficient. The following year there were reports that nearly all of the German programme was for medium doublehull over eas submarines, and the Admiralty chose to follow suit with a 'G' class.

The Royal Navy continued to develop large double-hull submarines during , but abandoned the type altogether postwar. The recent official history notes that its single great disadvantage was excessive diving time; all of the stability and reserve buoyancy problems of the single-hulled boats could be solved by appropriate saddle-hull design. The German cho e double-hull construction from the first, apparently in part because they demanded good seakeeping.

Concepts-in-Submarine-design.pdf

They initially went to single-hull designs only for small coastal types intended to operate from the Belgian bases Types UB and UC , although a much larger minelayer UE was also designed with a single hull, for simplicity of construction. In both UE and later versions of UB, small saddle fuel not ballast tanks were added for range, but, from the point of view of ballasting, all of these submarines were pure single-hull types.

With the later version of the UC minelayer, the designers returned to the double hull for improved surface seakeeping. In the German returned to the single hull for a new ton UF class intended pecifically to operate in the English Channel and the North Sea. They believed that by confining oil tanks to the interior of the hull they could eliminate leakage under depth charging, and thus improve the chances for escape.

A single hull also made for much quicker diving, and for simpler hence faster construction. Later an enlarged UF, UG, was designed to replace the relatively complex double-hulled UBlII; the single-hull concept was relaxed to the point of allowing water ballast but not oil fuel externally. Compared with UBIII, this design was considered simpler and stronger, having greater stability if reduced surface performance. Neither UF nor UG was completed, due to the end of the war. Postwar, German designers at first continued to develop their wartime doublehull or nearly double-hull designs, culminating in Type IA.

It had small saddle diving tanks while the main diving tank was in the pressure hull under the control room. Fuel oil was carried inside the pressure hull, to avoid leakage, as in the UF class.

Modern American and British designer favour single-hull submarines because they have a minumum of wetted surface, hence minimum drag, for a given internal volume. The new Los Angeles i a particularly extreme example, with all ballast tanks concentrated at the ends, outside the pressure hull. They have relatively little reserve buoyancy, and virtually the entire length of the pres ure hull i also the outer skin of the submarine.

By contrast, Soviet designers appear to favour double hulls for a variety of reasons. Their submarines often operate in ice fields, in which a single hull might be punctured. Great reserve buoyancy is thus an important safety factor. In addition, a double hull provides a measure of protection against contact attack, eg by ASW torpedoes. Many writers have suggested that Western lightweight torpedoes, such a the ubiquitou Mark 46, cannot penetrate both hulls of most Soviet craft.

Others would argue that the shock effect of even such small warheads would suffice, and that the resulting outer hull rupture would dramatically increa e the submarine's noise signature, hence its detectability. Full double hulls are relatively difficult to build and to maintain, because the compartments near the ends are necessarily very narrow and therefore difficult to inspect or to paint. Indeed, it appears that Soviet submarines have to be partially dismantled for hull maintenance, And, below a substantial displacement, the external tanks consume so much volume that the submarine proper is badly crowded.

Thus, although the Royal Navy favoured saddle hull designs, e sentially partial double hulls, its two smallest submarines 'H' and 'R' classes, about to tons surfaced, tons submerged were single-hull types. Professor Ulrich Gabler, the designer of the current German IKL submarines, has claimed that, for a given diving depth and cruising speed, the single-hull submarine will generally be smaller and less expensive than its double-hull counterpart.

It will also present a smaller sonar cross-section, but, on the other hand, the larger the expected radius of action, the more valuable the external tankage inherent in a double-hull design. Thus, although a single hull was the natural solution for German coastal submarines, double hulls were far better for the first generation of postwar ocean submarines.

Nuclear power is the exception, since external tankage does not contribute to the range of a nuclear submarine, only to the resistance of its hull. Submarines designed to spend most of their time on the surface had to be able to dive very quickly in an emergency, 0 that the reserve buoyancy so valuable on the surface had to be shed very quickly. Moreover, although much of the freeboard of a submarine was a free-flooding structure, there was orne question as to how rapidly it could be flooded.

Hence the standard World War II modification to US fleet submarines, in which numerou additional free-flooding holes were cut in their casings. The e arne hole added considerably to underwater drag, as well a to flow noise at high underwater peeds. The same submarine had already suffered when their streamlined superstructures were cut down to provide additional platforms for light anti-aircraft guns - a nice illu tration of choosing surface over underwater qualities.

The Briti h 'R' class of illustrates the elements of compromise as they were understood at the time. British submarine commanders in forward patrol areas had often sighted U-boats transiting on the surface, but had been unable to close them to attack. Between I January and I October there were sightings but only 13 successful anacks. The earliest proposal for a fast ASW submarine was made in March , but work began only later in the year. Anti-submarine attack required not only high speed, to get into position, but also a very powerful torpedo salvo, as the targets were small and agile, and as there would be little hope of a second hot.

Thus the original design called for a submerged speed of The price paid was in surface speed and in surface seagoing qualities. In both, British requirements conflicted with those of the Germans, the latter determining much postwar American and Japanese policy. The Germans saw surface performance as a means of reaching their often farflung operational areas.

Days lost in transit could not be made up, and underwater speed would matter little to a submarine spending most of its patrol time on the surface. By contrast, a British submarine in German waters would have to operate largely submerged after a hort transit time so the cost of a day could be discounted.

Hence the 'R' class designers were able to concentrate on underwater speed and manoeuvrability, at the expense of surface qualities. They cho e a single-hull design for minimum underwater drag, and further reduced drag by cutting away the freeflooding superstructure abaft the conning tower. Hull lines aft were very fine, for a combination of propulsive efficiency and agility reduced deadwood. Inside the hull, an unusually high fraction of the length, 35 per cent, had to be devoted to machinery, consisting of a bhp diesel and two electric motors, for a total of bhp 15 knot for 30 minutes, or By way of comparison, the contemporary conventional 'H' class, of similar size, had a bhp diesel for surface power and bhp submerged 13 knots and II knots, respectively , and the battery consisted of cells for the 'R'.

Postwar, the 'R' suffered in comparison with more conventional submarines due to very low surface speed 8 knot , and poor seakeeping; they were easily 'pooped' by following seas, due to very limited buoyancy aft.

If it is dry enough, even a submarine with relatively low freeboard can operate on the surface; hence the significance of the changes in the American'S' class in The earliest submarines were provided only with small armoured' watertight conning towers, in which their commanders could tand when they were submerged.

Before the development of periscopes, the only view was froin ports in this tower, and it was standard practice for the submarine to rise intermittently to just awash during its approach to the target. Surface performance was another matter. At first, there were no permanent bridges, and orders had to be shouted down an open conning tower hatch.

The conning towers of early British submarines were so short that high waves could wash over them, swamping the boat. But the British view was that the conning tower per se was no more than a passageway between the control room and what became a permanent bridge.

There was little point in passing the periscopes through this relatively narrow tube. The first British submarine with this type of conning tower was C in , and this system persisted in all later boats.

A recent British official historian observed that there was a conflict between a desire to increase the length of periscopes to increase periscope depth for safety and the need to be able to dive in hallow water, which in turn made a low silhouette attractive.

Typically British conning towers had upper and lower watertight hatches, to provide extra security against flooding by wave breaking over the bridge. The US Navy followed a rather different path. From the large V-4 on , it placed periscope eyepieces in large conning towers rather than in the control room located in the pressure hull proper. Total periscope length was fixed by the height of the structure above the bridge, which determined in part the ize of the silhouette the submarine presented on the surface; when housed, the lower end of the periscope was nearly at the keel.

However, periscope depth was determined by the height of the eyepiece above the keel; by placing its eyepieces in the conning tower, the US Navy and other navies employing similar configurations gained about 10ft. They also gained in periscope height above water, hence range, when the periscope was used for look-out on the surface.

In mo t US fleet type submarines, the conning tower contained an attack centre from which the captain operated, although most of the ship controls were in the compartment below. This separation led to later demands for amalgamation of the attack centre and the control room.

The separate conning tower's great disadvantage was its bulk adding resistance underwater. That was no great problem as long as high underwater speed was not demanded, but in the US Navy began to develop a fast underwater submarine, which became the Tang. One of the first measures taken was to forego the conventional conning tower, to reduce the bulk of the fairwater enclosing the periscopes, snorkel, and surface bridge.

Perhaps surprisingly, the loss of periscope depth was not universally accepted, and both Darler diesel and Seawall nuclear of the mids had small conning towers justified entirely in terms of increased periscope depth. Later designs lacked conning towers; underwater speed was far too important. Conning tower design is only one factor affecting another important aspect of submarine design, performance near but by no means at the surface.

The classic problem of a submarine at very shallow depth is that sudden changes in trim as when a torpedo is 24 fired or even violent waves can so change its buoyancy as to cause it to surface inadvertently, to broach, and 0 to expo e itself.

The entire issue might be thought obsolete in an era of nuclear submarine, but that is so far not the case that attempts to eliminate the ail as a majorsource of underwater drag in US submarines have generally died in the face of requirements for periscope-depth performance. Historically, depth keeping was essential if an attacking submarine was to be able to make periodic periscope ob ervations of its target; the periscope was the only effective attack en or.

Then near-surface depth keeping became important for snorkelling; the snorkel had to be kept out of the water, but not too far out ie too detectable. For example, at least in early installations, each time a wave shut down the snorkel air intake the diesels would begin to suck air out of the boat so violently that air pres ure would drop rapidly. Nuclear propulsion solved that problem, and it might be argued that the periscope is of little value in submarine v submarine duels.

But thi is not the only important current submarine role. For instance, the covertness of the submarine makes it an ideal platform for collecting electronic and even photographic intelligence, for both of which it mu t project sen ors out of the water.

The public discussion of US submarine intelligence mission into Soviet fleet operating areas using Slurgeon class boats can be read alongside statements that this design shows a much taller sail than its predecessors, a feature which would keep the submarine deeper under water when at periscope depth, and thus would make it Ie s responsive to surface wave motion. One of the two central problem of submarine development, until late in the nineteenth century, was to provide reliable underwater power.

The first solution wa the electric motor, supplied by a storage battery. The major drawback was very limited endurance, just as in an electric car.

Even so, a fully electric boat capable of submerging and of travelling a limited distance submerged was clearly useful for harbour defence, and a number of such submarines were built at the end of the nineteenth century, especially by the French Navy. Limited high speed underwater endurance is still a problem for conventional submarines. Submarine underwater speeds are usually quoted at a maximum battery discharge rate, which cannot last for more than an hour or two.

Hence the need for surface operation, in which the submarine could be powered by a long endurance fossil-fuelled engine also able to recharge its batteries.

That was. The other nineteenth century problem was trim control. Early submarine inventor tended to fill their ballast tanks only partly, to compensate for water density and details of weight aboard their craft. As a result, they suffered badly from the effects of free water surface. They also tended to try to hover; without any waterplane area, their boats had little longitudinal stability. John Holland solved both problems by relying on dynamic as well as static forces, by using the lift generated by hull and hydroplanes as his ubmarine moved through the water.

That controlled lift could balance off weight and trim imbalance, so that, for example, ballast tanks could always be entirely filled. The combination of separate surface and underwater powerplants was the key to strategic mobility, and even to the ability to deal with high-speed target in the open ocean.

In the latter case, a typical submarine tactic was to run on the surface, just out of visual range of a target ship or convoy, either submerging to attack or waiting for night to deliver a surface attack.

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The surfaced submarine would dive to frustrate pursuit. In either case, high surface speed was vital, and that in turn required relatively large surface engine, which made claim on limited internal space. They competed with battery space and with electric motors and generators. The size of the latter determined, at least to a large degree, underwater endurance, since they recharged the batteries when the submarine ran on the surface or, later, snorkelled. Here there wa much room for complicated compromises.

For example, the US Navy ultimately chose to connect its diesels to generators, always running the propellers on electric motors.

When a fleet submarine ran on the surface, it would always be charging it batterie , since power would always be fed through them. This was a relatively cumbersome system, and represented a sacrifice of space and weight. The benefit was a higher surface speed when charging batteries; in some other navies diesels had to be de-clutched in order to connect them to the generators. Diesels were by no means the only surface powerplants tested.

Compared to steam turbines, they produced relatively little power for their weight. Steam engines seemed attractive for high surface speed. Their major drawback was twofold; they required many more openings in the pressure hull, a potential diving hazard, and they took much longer to start up and to secure. The first problem was particularly evident in the fast British 'K' class submarines of , which needed steam turbine power to reach battle fleet speed.

The second was exemplified by the early French steam submarines sometimes taking as long as 15 minutes to submerge. Even so, when the US Navy sought very high surface speeds after for submarine radar pickets, it returned to steam plants. One result was the pressure-fired boiler for a steam turbine, a machinery plant ultimately employed only in surface Ships.

The entire concept of using two separate powerplants was extremely expensive for anything as volume-critical as a submarine, but it was inescapable; only fossil fuels could store sufficient energy for sustained high power in a limited volume. They in turn required oxygen, and no submarine could carry a sufficient volume for extended underwater operation.

There were attempts to use high power underwater, the most notable being the German Walter turbine, but they were all very limited in endurance by the volume of oxidiser the submarine could carry.

Thus, until the advent of the snorkel, high sustained power meant surface operation. A submarine exercising its longrange mobility became, temporarily, a surface ship, giving up its stealth entirely. Even while norkelling, the snorkel head itself is detectable and it is larger than an attack periscope so there is still a acrifice of invisibility.

One former ASW pilot referred to a snorkelling submarine as 'a small surface vessel' which had abandoned its essential submarine quality. Typically submarines snorkel intermittently in hopes of avoiding excessive exposure, and, therefore, detection. Moreover, when it is snorkelling, a submarine is limited in speed, partly to avoid damage to the snorkel itself.

Partly, too, the snorkel is generally used to charge batteries, so that only a fraction of the power being developed goes directly into propulsion. For example, a modern German IKL submarine may make only 5 knots on its snorkel, but as much as 22 knots at maximum battery rate submerged. The nuclear submarine is at present unique in combining underwater and long-range propul ion, because it alone packs very high energy densities into a fuel requiring no oxygen for its combustion.

Nuclear plants are also unique in that they are so powerful that excess energy becomes available for many auxiliary functions. For example, it is typical for nuclear submarines to renew their atmospheres by hydrolysi, extracting oxygen from the water through which they steam. A conventional submarine attempting to remain underwater for an extended period usually uses chemical devices such as 'candles', which are less effective. Almost certainly, too, only a nuclear submarine has sufficient excess electrical capacity to power a very large active sonar; certainly commanders of nuclear aircraft carriers have remarked on the degree to which their powerplants assured them of sufficient energy for their electronic systems.

New in Cambridge Ocean Technology Series: Concepts in Submarine Design Series Number 2. Description This book explores the many engineering and architectural aspects of submarine design and how they relate to each other and the operational performance required of the vessel.

Concepts of hydrodynamics, structure, powering and dynamics are explained, in addition to architectural considerations which bear on the submarine design process. The interplay between these aspects of design is given particular attention, and a final chapter is devoted to the generation of the concept design for the submarine as a whole.

Submarine design makes extensive use of computer aids, and examples of algorithms used in concept design are given. The emphasis in the book is on providing engineering insight as well as an understanding of the intricacies of the submarine design process.

It will serve as a text for students and as a reference manual for practising engineers and designers. Other books in this series. Add to basket. Ocean Waves: Series Number 4: Fundamental Aspects Volume 1 R. Series Number 5: Practical Considerations Volume 2 R. Table of contents Introduction; 1. Design in general; 2. Milestones in submarine history; 3. Submarine hydrostatics; 4.

Submarine structures; 6. Powering of submarines; 7. Geometric form and arrangements; 8. Dynamics and control; 9. Submarine systems; Figure 6. Given a fixed demand for internal deck space, the submarine designer can choose from a variety of external hull forms.

As previously described, the pres- 3. Moreover, it appears that the Soviets are much less concerned with avoiding detection than are their Western counterparts; they rely on aggressiveness, numbers and speed to attack and then to evade. This book will serve as a text for students and as a reference manual for practicing engineers, naval architects, and designers. Their major drawback was twofold; they required many more openings in the pressure hull, a potential diving hazard, and they took much longer to start up and to secure.

The mere ability to dive to a moderate depth was sufficient to defeat visual detection under most circumstances, which is why submarines had only limited diving depths up through the early part of World War II.

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