[Ed. Note: CMneral Menez’s equivalent rank is Vice Admiral, Naval Constructors Corps.]
Introductory Remarks
In my previous paper (What Price Speed?, Submarine Review, October 1993), I recalled the simplified relationship that can be established between maximum speed and total displacement for a given payload:
View full article for table data
This relationship, derived from a volume equation which is the main tool in submarine preliminary design (rather than weight equation), is based upon an unlimited anaerobic energy (i.e. nuclear) propulsion plant design. In submarines, at a preliminary design stage, volume equation supported by a drawing is usually preferred to weight equation alone.
This formula is of value in a wide range of designs. However, it becomes less valid at the limits, when some parameters can no longer be considered as constant. For instance, specific power of the propulsion plant v becomes larger and cannot be considered as a constant when maximum power decreases.
There are also other limits to the validity of this relationship, coming from the other equations or inequations (weight, stability …) which must be satisfied in any design. A smaller propulsion plant of lesser maximum power which can be suitable in a low maximum speed design needs a better (i.e. heavier) radiation shielding, as maximum speed is of more common use than it is in a higher maximum speed design. This may lead to buoyancy and/or stability problems which react on the design.
These remarks, however, have no significant influence on the tendencies derived from our basic relationship which remain roughly true.
Cost and Displacement
When writing my previous paper, I made use of the term price in an ambiguous meaning. My aim was to show clearly that maximum speed had a price to be paid in volume, i.e. displace-ment, with no direct reference to money. In my mind, it went without saying that displacement was also related to cost in money.
Since I wrote that paper, I had the opportunity to read thoroughly Rockwell”s .Rickover Effect, in which the opinion of the Admiral in that matter is strongly expressed in the paragraph entitled Dinner with Edward Teller with an example derived from clock making.
” …Teller greeted us at the door, and before we could get our coats off, he stated the purpose of the visit. “Rick, you’ve got to build smaller submarines. ”
I bristled . This was a subject we had debated often, and I was ready for it. But Rickover’s response was calm and relaxed . “Why, Edward? The oceans are very big. ” “We will need lots of them, Rick. Lots of them. ”
“We can build lots of them, Edward.”
“No, they are too expensive.”
“Ah, you don’t mean they should be smaller. You mean they should be cheaper.”
“Isn’t it the same thing?”
“Not at all. You used to be able to buy a big Ingersoll pocket watch for a dollar. I suppose it’s a bit more now. But a tiny lady”s wristwatch is very expensive. Even without diamonds on it. No, smaller doesn’t mean cheaper. Not at all.”
The example put forward by Rickover is based on valuable knowledge of clock making, but it does not seem so valid when compared with submarine manufacturing.
In the mechanical clockwatch era, continuous progress in clock design and clockmaking was achieved by mass production directed to an ever increasing market. This single function item became therefore, more and more compact, whereas its price was falling. This does not mean, however, that the evolution of price per unit weight or volume for clocks over long periods, in constant money, was a decrease. Let us nevertheless assume that this evolution was such, although we have no publication to support this opinion. Equally, this does not mean that all watches were sold at the same price. Small ladies’ watches included expensive precious metals and needed more labor for their elaboration, leading to higher prices and thus making the market smaller.
With the evolution to electronic watches, all the data became obsolete. More expensive multifunction watches became available, together with low cost single function watches (Swatch).
There is no reason why a complex system like a submarine should follow the same laws in a market which, by the way, remains quite small .
Submarine design is governed by volumes and no volume is unduly created unless it is a useful one, because the propulsion plant should be increased accordingly and, consequently, the overall displacement. For instance, growth margin in volume, if incorporated in the design, is limited to a fairly low value.
Displacement, resulting from volume, is therefore a good evaluation of the costs which are to be expected at the beginning of a new design, although every volume is not given the same cost.
Technological Evolution
Since the very beginning of their history, submarines have incorporated various technologies in their design which have been subject to large improvements, occurring step by step with a quantum variation and no true continuity or simultaneity.
Referring only to the nuclear submarine’s era, this evolution has first been concentrated on energy production and propulsion, then on noise reduction techniques, then on sonar improvement, which relies largely on digitalization and data bussing. Large arrays have become feasible, leading to high capacity data processing. Other steps could be put forward, for instance in the domain of communications. In all these changes, mechanical parts which are essential in energy production and propulsion have been subject to less variations in techniques and costs than electronics, where digitalization, in particular in sonar systems, has allowed a large increase in capacities for a given volume, leading to a considerable evolution of costs. For instance, software may well reach tremendous costs by adding neither volume nor weight.
In constant money, cost per unit volume of nuclear submarines has grown quite evidently between successive generations of submarines, but at a moderate rate, due to the leverage effect of mixed mechanical, electrical and electronic technologies. Evolutions of 10 to 20 percent may well be put forward. Volume or displacement, as a result, is a good approach to the cost of a given design, provided that there is a means to cope otherwise with the influence of technical evolution on cost per unit volume. This may well be difficult when a new project is initiated and may lead to additional uncertainties on cost evaluation. These uncertainties may, however, be maintained at 10 percent or below, provided that a rough assessment of the technological evolution factor is made at the beginning and checked along the design process.
Dimensions
As mentioned in my previous paper, assuming that the designs are all of the ALBACORE type, which is very common in the Western world, the diameter of the pressure hull cannot be chosen at random. To accommodate properly crew and ship’s systems, the diameter of the pressure hull (hence of the hull in a single hull design) must be made close to preselected values leading to a good occupation of available space.
Preferential values are about 8 m ( – 26 ft), 10.5 m ( – 34 ft), 13m (-43ft).
As the ratio of length to diameter cannot be too small or too high, each diameter covers properly a range of overall volumes, with some problems occurring at the overlap.
The following figures can be given.
View full article for table data
Speed Capacity for Smaller Diameters
In the 8 m (26 ft) diameter range, it is known by practice that it is possible to design a submarine with:
V, = 3,200 m3 (113,000 cu.ft) V. = 1,100 m3 (39,000 cu.ft) Sm = 25 kn
Coming back to the full form of our relationship, we can write that:
Larger Diameters
A wide range of attack submarine designs can be covered when a single 10.5 m pressure hull is adopted.
This can be derived quite easily from SSBNs, whole characteristics can be assessed to be:
Vl – 11,000 m3(388,700 cu.ft)
Vv– 7,000 m3 (247,300 cu.ft)
Sm – 25 kn
The maximum speed of 30 len can be obtained for a set of Vt, Vv plotted as an example in the following table:
View full article for table data
Needless to say, 13 m (43 ft) diameter designs are not to be considered for attack submarines at the present time.
Conclusions
It has been shown in the three previous paragraphs that a useful volume of 1,500 m3 (5,300 cu.ft) can be accommodated either in a 3,200 m3 {113,000 cu.ft) 8 m (26 ft) in diameter submarine propelled at about 23 kn+, or in a 6,000 ml {212,000 cu.ft) lO.Sm {34ft) in diameter submarine propelled at about 30 kn.
Higher useful volumes probably require 10.5 m {34 ft) diameters, although a more accurate definition of this boundary should be useful, if one considers its impact on costs.
Smaller useful volumes of 1,100 nr {39,000 cu.ft) can be accommodated in a wider range of designs tabulated here.
View full article for table data
Two questions should be addressed now which require more operational and thus more classified considerations.
Is a 30 len maximum speed much better than a 23 len maximum speed, if one considers its impact on total volume of a design for a given useful volume?
I am not going to answer this question. My personal feeling, subject to controversy, is that the maximum usable speed, which is the only important one, is a quiet speed at which good passive detection can be achieved (limited self-noise) and counter-detection avoided (limited radiated nose). In the various designs considered here, it is most unlikely that large differences in maximum speeds will lead to appreciable differences in maximum usable speeds.
The true question, which I cannot address at all, is the second one.
Is a useful volume of less than 2,000 m3 (70,600 cu.ft) acceptable for a capable enough attack submarine?
This question leads to difficult discussions on what is essential, what is not. It also leads to questioning the general purpose design, that is to say a design including all capacities deemed necessary, sticking once more to the best capable.
In my view, more specialized designs of the 8 m+ (26 ft+) diameter with a speed limited to 25 len are to be considered in the future. These specialized designs should have as much commonal-ity as possible, in order to achieve a low unit price.
This does not mean, however, that no developments are necessary to achieve the required compactness. I suspect the contrary is probably true. For instance, BQQ5 or 6 forward antennae cannot easily be made compatible with torpedo tubes in an 8 m+ (26ft+) diameter design.
Neither does this mean that the inventory of a submarine force based on several specialized designs should not be higher than the one based on a general purpose design. As a whole, the total expense in the long term might well be higher. But in these matters, only the annual amount of budgetary money is of real importance. If such a policy were adopted, it should probably be easier to adapt programs to annual budgetary resources, which is the main financial constraint.
{Ed. Note: We regret that the final two paragraphs from Vice Admiral Menez’ article What Price Speed (October 93/ssue) were omitted. The missing paragraphs, which should have followed from page 36, are printed below. The formulae on page 36 for V,..,. and for V, were printed with the incorrect Power for the variable Sm. The co”ect formulae are: View full article for table data We sorry for any inconvenience]
WHAT PRICE SPEED (October 93) (Final Paragraphs)
In wartime or pre-wartime situations, fast deployment to places where increasing tension is observed must be considered. But as a rule this cannot be done without caution. Covertness must be achieved and the maximum usable speed is a speed at which good passive detection can be obtained (limited self noise), and counter detection avoided (limited radiated noise), that is to say a speed of between 15 and 20 len maximum.
In conclusion, a high maximum speed seems of very little use in wartime conditions, while its usefulness in peacetime may also be questionable. Since it represents a heavy burden in any design where high speeds are required, why not consider the possibility of lower values?
