Appendix D
Data anomalies
The anomalies listed below are shown merely to inform the reader. There is no suggestion the data presented in this article is correct beyond doubt, that is for the reader evaluate.
1) The eminent naval writer Norman Friedman in his "SUBMARINE DESIGN AND DEVELOPMENT " states -
the Guppies came quite close to the performance of the Tang. A 1953 comparison shows the latter no faster submerged, but its specialised design (and shorter hull) showed in much better manoeuvrability and better longitudinal stability.
This seems at odds with the original model towing tank curves that show the yet unnamed, "261 ft sub" was 2 to 3 knots faster than the Guppy. However we are given no detail of the 1953 trial or which of the Tang class was trialled. In 1958 the first four Tang class were extended due to the forced replacement of the novel but troublesome 'vertical pancake' engines with more conventional engines. Two were actually built longer with the new engines. Then in 1967 four of the class receive another extension to accommodate PUFFS sonar - a changing scene!
The electrical propulsion system was a modified version of the Guppy with a modest increase in power propelling a more efficient submerged high speed hull than that of the Guppy.
2) The reasons for the GIA/GIIA conversions?
Alden tells us that -
Because of the high cost of the Guppy II conversion, the Bureau of Ships devised two less expensive modifications in which the major change was the abandonment of the four-battery arrangements. Instead, a new higher-capacity battery of standard size, the so-called SARGO II type, was developed and the original battery wells were left unchanged
On the other hand -
Friedman in his book "SUBMARINE DESIGN AND DEVELOPMENT " page 65 says-
But the new battery used twice as much lead as a conventional one, and wore out twice as fast, with an estimated life of only 18 months. There was some fear, in the late 1940s, that there would not be enough lead for the conversion programme; the existing foreign sources were either in hostile hands (Balkans) or in an unstable area (Burma). Later conversions (Guppy II') employed a conventional Sargo II" battery
Friedman's " - used twice as much lead etc" comment, seems contrary to the actual decrease in mass from 232 tonnes to 192 tonnes. The mass of the SARGO I was the same as the SARGO II. The new cells, both GUPPY I and SARGO II apparently used more but much thinner plates.
The guaranteed cell service life - SARGO I = 600 cycles or 72 months. SARGO II = 400 cycles or 48 months. Guppy 1 = 300 cycles or 30 months.
Obviously the actual service experience is what counts, together with the mass of the total electrolyte and the amount of case material with twice the number of smaller cell cases and so on, but the apparent anomaly seems worth drawing to the reader's attention.
3) The figure of 1719 hp per propeller shaft submerged (total 3438 shp) given in NavPers 16162 is higher than the power given by other sources.
Checking for a comparison in BR3043, the 1932 Royal Navy Thames Class of Fleet Submarine displaced 2680 tons submerged compared to the US Fleet Submarine of 2400 tons. Appendix I
The specification was 10 knots for 1.3 hours developing 2500 shp. During trials 10.58 knots for one hour was achieved developing 2585 shp. A figure significantly lower than the figure of 3428 shp given for the USN submarine.
The preserved Fleet Submarine USS Pampanito web site data states 9 knots for one hour developing 2400 shp.
These are also the figures given by the authoritative Commander Alden.
However if the motor shunt field characteristics allowed (and this is unknown) it is possible that the higher shp was achievable for a period less than one hour for speeds greater than 9 knots, but so far there are no anecdotes or reports to support this.
4) NavPers 10490 states that
The capacity of a GUPPY cell is about 90% of that of a SARGO type
This is a rather ambiguous figure as the percentage capacity depends on the hourly rate used. At the more usual comparative 5 hour rate, the correct figure is 75%. At the 1 hour rate the figure is 81.6% and at the 1/2 hour rate the figure is 84%.
On the same page there is an undoubted dimensional error in regard to the SARGO where the width of 15 inches is shown as 21 inches.
As the length is actually 21 inches, this error would make the SARGO cell square and this, it was not!
5) Friedman, again in - "SUBMARINE DESIGN AND DEVELOPMENT", Page 65 gives some Guppy figures -
The full Guppy conversion replaced the original pair of 126-cell batteries by four new 126-cell units, each two-thirds the weight but with about 75% more capacity. That almost doubled available underwater power at the high discharge rate (4250 vs 2638 shp for one hour). At the medium (6 hour) rate, the 'Guppy' battery had 50% more energy
Taking the Guppy 1 cell specification one hour data = (4340 amps x 2 x 424 volts x 0.9) / 746 = 4440 shp, add 134 hp auxiliary load to Friedman's 4250 shp and we have a close match. The 134 hp is as used in Appendix B.
A similar calculation for the original SARGO 1 of the Fleet Submarine gives 2655 shp, very close to Friedman's figure. So far so good.
He goes on.
Later conversions of the (Guppy II') employed a more conventional 'SARGO II' battery, and were limited to 15 knots underwater, compared to the 17 of a 'Guppy' battery submarine
He clearly relates the power increase to 4250 shp with a submerged speed of 17 knots.
This information suggests that the Guppy II could achieve 17 knots at the one hour rate when this article has firmly taken the high speed to be 16 knots at the 30 minute rate for a number of good reasons including the anecdotes of people who operated these submarines. Appendix B and Appendix H
As Friedman does not give any reference sources or the circumstances in which these figures were derived - we are at a technical impasse, as it were!
Additionally if the one hour rate is accepted as being correct in relation to the Guppy maximum speed/power/endurance then the Guppy II would not only have significantly exceeded the maximum submerged speed of the RN converted T Class, but achieved this using only 73% of the power, for twice the endurance period! A remarkable difference, especially when one considers that the converted T Class actually had a slightly higher AH capacity than the GII! Appendix F
Regarding the "two-thirds of the weight" comment. (GUPPY cell = 460 kg - SARGO I cell = 760 kg. 60.5%. Close enough.
Continuing, "but with about 75% more capacity". The comparison is apparently between 126 battery units with no hourly rate specified but assuming the usual comparative 5 hour rate then the 126 cell batteries were 75% of the capacity of the original. The key factor was doubling the number of batteries - an overall increase of 150%. The equivalent numbers at the one hour rate are 81.2% and 63%. At the half hour rate, 84% and 68.3%
And "That almost doubled the power at the high discharge rate (4250 vs 2638 shp for one hour)". The shp numbers are close enough to the calculation 4306 vs 2543 shp in Appendix B - though the statement "almost doubled" is misleading, 4250 / 2638 = 1.61. Close to the 63% above.
The statement "6 hour rate had 50% more energy", is correct.
Friedman lowers the Guppy speed in his book "THE POST WAR NAVAL REVOLUTION - Submarines Page 191", when he makes a brief reference to maximum speed and tells us that -
The Guppy conversion entailed new batteries and modified motors; underwater speed increased from about 10 knots to as much as 16 knots.
The detail in MOTORS and CONTROL CIRCUITS cannot be seen as a motor modification.
6) Alden states that the conversion from GII to GIII, involved inserting a 15 foot section, while Friedman in "SUBMARINE DESIGN AND DEVELOPMENT" Page 66 in a caption to a photograph of USS Pickerel(SS 524), tells us it was 10 feet. Alden in addition, tells us that the USS Tiru (SS 416) was unique in only having a 12.5 foot insertion due to the fact she had only three engines and perhaps had already had more space than the rest of the GII.
The British military historian, Richard Humble, in his book 'UNDERSEA WARFARE" Page 122 states incorrectly that the original Guppy conversions of 35 submarines involved a 15 foot insertion into the hull. His figures of 20 Balao and 15 Tench submarines don't seem to relate to the program detail given by Alden?
K&C Bonner in their COLD WAR AT SEA P 337-38 - re' the main Guppy program
The boat were turned into jumbo size by slicing them in half and adding a 15 foot section.
7) These technical anomalies are not confined to the USN Guppy submarine - for instance the British A Class - Friedman in his book "SUBMARINE DESIGN AND DEVELOPMENT " Page 66.
the large A Class was also rebuilt. It was long enough to fit enlarged batteries, and reportedly the original electric motors were not replaced. Like the fast T Class, the rebuilt A Class had an underwater speed of 15 knots
Yet in another of Friedman's books "POST WAR NAVAL REVOLUTION" Page 192, in a caption alongside a 1961 photograph of my old boat Amphion with her streamlined "face lift" he correctly says -
However, larger motors were not fitted, so speed did not materially increase.
The A Class motors were only 1250 shp, actually smaller than older T Class - 1450 shp. The Converted T Class had their motor shp increased to a nominal 6000 shp, in practice about 5800 shp. Appendix F
RN Submarine Museum, owners of the preserved Alliance say 10 knots submerged. The A Class were not a particularly large submarine at 1620 tons submerged'
A 25% increased in battery capacity was gained by fitting modern cells of the same dimension in the existing tanks.
In fact the streamlining of the A Class, 1955 to 1960 was similar to the five streamlined T Class. Appendix I
8) Friedman is not alone, Eric Groves, the esteemed British historian, also confuses in regard to the A Class in his book "FROM VANGUARD TO TRIDENT" and tells us that -
The A class were modernized with new streamlined bows and sterns and large streamlined fins. Battery capacity was increased, although unlike the T Class Conversion, the motors were not enlarged as they were more powerful anyway
A reader unfamiliar with these submarines might well believe that the A class was converted in the manner of the major T Class Conversion and could achieve the faster speeds in the order of 15 knots like the converted T Class or the US Guppy.
The A Class was a 'front line' submarine in the Royal Navy from 1945 to 1958 when the Porpoise Class first appeared.The fact that the A Class was not converted for high submerged speed is an important part of any interest in Royal Navy submarine policy in the years following WWII.
It was fact, in many respects a very good submarine of WWII design, but no major changes were made to the propulsion throughout the long service of these submarines, despite Miller in his "SUBMARINES OF THE WORLD" giving the streamlined 'A' four 1075 bhp diesels instead of the correct and original, two 2150 bhp
He also gives the streamlined A Class a submerged speed of 15 knots!
9) Usually these technical data anomalies can only be checked properly by access the original sources, for instance Kemp's otherwise excellent book "THE 'T' CLASS SUBMARINE" reports that the Taciturn, when carrying out speed trials, achieved 17 knots on the surface. A big improvement on the direct drive diesel speed trial. Unfortunately he goes on to attribute the improvement to the new diesel-electric mode provided in the conversion. This was clearly not correct as the contrary situation was in fact the case, the diesel-electric mode being always slower than the same diesel engines in direct drive.
A review of the 1952 official trial document revealed that the surface speed of 17 knots was actually achieved using the enlarged fast battery electrical propulsion system that would normally have been used when submerged. See T Class Conversion.
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