View source for French submarine Charles Brun

{{short description|1906 experimental naval boat}}
{{good article}}
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{{Infobox ship image
|Ship image=Charles Brun (1911).jpg
|Ship caption=''Charles Brun'' in [[Toulon]] [[roadstead]], 1913
}}
{{Infobox ship class overview
|Name=''Charles Brun''
|Operators={{navy|France}}
|Class before={{ship|French submarine|Amiral Bourgois||2}}
|Class after={{sclass|Clorinde|submarine|4}}
|Cost=
|Built range= 1907–1912
|In service range=
|In commission range=
|Total ships completed=1
|Total ships scrapped=1
}}
{{Infobox ship career
|Hide header=
|Ship country=France
|Ship flag={{Shipboxflag|France|naval}}
|Ship name=''Charles Brun''
|Ship namesake=[[Charles Brun (France)|Charles Brun]]
|Ship ordered=31 December 1906
|Ship builder=[[Arsenal de Toulon]]
|Ship original cost=
|Ship laid down=4 April 1908
|Ship launched=14 September 1910
|Ship christened=
|Ship completed=
|Ship commissioned=  
|Ship struck=7 June 1920
|Ship fate=Sold for [[ship breaking|scrap]], 30 December 1920
|Ship notes=
}}
{{Infobox ship characteristics
|Hide header=
|Header caption=(as built)
|Ship type=[[Submarine]]
|Ship displacement=*{{Cvt|360|t|LT|0|lk=on}} (surfaced)
* {{Convert|453|t|LT|0|abbr=on}} (submerged)
|Ship length={{convert|45.6|m|ftin|abbr=on}} ([[o/a]])
|Ship beam={{convert|4|m|ftin|abbr=on}}
|Ship draft={{convert|3.6|m|ftin|abbr=on}}
|Ship power=*4 Maurice boilers
*{{cvt|1300|PS|0|lk=on}} (steam)
*{{cvt|200|PS|0}} (electric)
|Ship propulsion=*2 [[propeller shaft (ship)|shafts]]
*2 [[Marine steam engine#Triple or multiple expansion|triple-expansion steam engines]]
*2 [[electric motor]]s 
|Ship speed=*{{convert|13.5|kn|lk=in}} (surfaced)
* {{convert|7.25|kn}} (submerged)
|Ship range=*{{cvt|1050|nmi|lk=on}} at {{convert|7|kn}} (surfaced)
*{{cvt|10.7|nmi}} at {{convert|2.8|kn}} (submerged)
|Ship test depth={{convert|30|m|ftin|abbr=on}}
|Ship complement=25
|Ship armament=* 2 × {{convert|450|mm|in|1|abbr=on}} bow [[torpedo tube]]s
*2 × single 450&nbsp;mm [[Drzewiecki drop collar]]s
*2 × single external 450&nbsp;mm torpedo launchers
}}
|}
'''''Charles Brun''''' was one of four experimental [[submarine]]s ordered for the [[French Navy]] in 1906. Each boat was built to a different design and ''Charles Brun'' was intended to test a novel powerplant. Although the shore-based [[prototype]] installation was successful, it was a failure when evaluated aboard the submarine, and the boat was never [[Ship commissioning|commissioned]] for active service. Her [[hull (watercraft)|hull]] was stripped of its equipment and was used to test a [[floating drydock]] in 1914. During the [[First World War]], the hull was ordered to be converted into a water tank in 1916, but it is not certain if this was actually done before it was sold for [[ship breaking|scrap]] in 1920.

==Background==
The [[naval architect]] and engineer Just Lucien Maurice had submitted multiple submarine designs to the Navy's Board of Construction ({{lang|fr|[[Conseil des travaux]]}}) using a unique [[Air-independent propulsion|closed-cycle]] powerplant of his own design. The board rejected the four proposals that he submitted in 1902, believing them to be too high risk and that their submerged range was inadequate. The [[List of naval ministers of France|Navy Minister]] ({{lang|fr|Ministre de la Marine}}), [[Jean Marie Antoine de Lanessan|Jean de Lanessan]], was intrigued by his concept and ordered that a prototype of his powerplant be built at the [[Cherbourg Naval Base]] ({{lang|fr|Arsenal de Cherbourg}}) for testing.<ref name=r4>Roberts, p. 444</ref>

Maurice had designed a steam [[fire-tube boiler]] that utilized the boiler's combustion gases to heat a mixture of [[sodium acetate]] and [[potassium]] in the space between the two concentric fire tubes. Once the mixture melted at a temperature of {{convert|212|°C}}, it would then heat the water in the boiler and the resulting steam would be fed to a conventional [[Marine steam engine#Triple or multiple expansion|triple-expansion steam engine]]. When the submarine submerged the mixture would retain heat, continuing to generate steam, until it solidified.<ref name=r4/>

The prototype at Cherbourg was successful enough that Navy Minister [[Gaston Thomson]] opened a competition for submarines that were faster on the surface and with longer range than the preceding {{sclass|Pluviôse|submarine|4}} on 6 February 1906. Surfaced requirements were for a maximum speed of {{convert|15|kn|lk=in}}, a range of {{convert|1250|nmi|lk=in}} without using an auxiliary fuel tank, and a range of {{cvt|2500|nmi}} with the extra fuel. Submerged, the boats had to have a maximum speed of {{convert|10|kn}} and a range of {{cvt|100|nmi}} at {{convert|5|kn}}. Four designs were submitted, including Maurice's for ''Charles Brun'', all of which were authorized by the board.<ref>Roberts, p. 442</ref>

==Description==
''Charles Brun'' was significantly smaller than the other designs submitted for the competition with a surfaced [[Displacement (ship)|displacement]] of {{convert|360|t|LT|0|lk=on|sp=us}} and a submerged displacement of {{cvt|453|t|LT}}. The boat had an [[overall length]] of {{convert|45.6|m|ftin}}, a [[beam (nautical)|beam]] of {{convert|4|m|ftin|sp=us}} and a [[draft (hull)|draft]] of {{cvt|3.6|m|ftin|sp=us}}. Her crew numbered 25 officers and sailors.<ref name=r5>Roberts, p. 445</ref> She had a [[test depth]] of {{convert|30|m|ft|0|sp=us}} and a [[metacentric height]] of {{cvt|0.432|m|ftin|0}} when surfaced. Like most French submarines of this period, ''Charles Brun'' was fitted with a prominent "walking deck" above her [[Submarine hull|single hull]] to facilitate operations on the surface.<ref>Garier, pp. 210, 212, 216</ref>

The submarine's hull was divided into seven [[Ship floodability|watertight compartments]] plus the [[conning tower]]. The boat had three [[rudder]]s, two below the [[waterline]] and the third above the "walking deck" to improve her submerged maneuverability. She had three sets of [[diving plane]]s, fore, aft, and [[amidships]], to control her depth below the water. The hull was fitted with a dozen external [[ballast tank]]s and three internal tanks, one of which could be used as an auxiliary tank for [[fuel oil]]. Normally, ''Charles Brun'' had a capacity of {{convert|11440|L|sp=us}} of oil, plus another {{cvt|2000|L}} that could be stored in the ballast tank.<ref>Garier, pp. 209–210, 212–213</ref>

On the surface, the boat was powered by a pair of three-cylinder triple-expansion steam engines, each driving one [[propeller shaft (ship)|propeller shaft]] using steam provided by two pairs of Maurice boilers that had a working pressure of {{convert|30|kg/cm2|kPa psi|0|abbr=on|lk=on}}. The engines were designed to develop a total of {{convert|1300|PS|lk=on|sp=us|0}} and a maximum speed of {{convert|13.5|kn}}.<ref name=r5/> Submerged, the steam engines could be supplemented by a pair of {{convert|100|PS| kW|0|adj=on|sp=us}} [[electric motor]]s using electricity from 120 [[Tudor batteries]].<ref>Garier, p. 211</ref>

Internally, ''Charles Brun'' was armed with two superimposed {{cvt|45|cm|in|1|sp=us}} [[torpedo tube]]s in the bow. Externally, the boat was equipped with two rotating [[Drzewiecki drop collar]]s below the "walking deck" and two fixed launching frames at the [[stern]] aimed to the rear.<ref name=r5/>

== Construction, trials and subsequent history==
''Charles Brun'', named for the naval architect and politician [[Charles Brun (France)|Charles Brun]] who had worked on the first {{ship|French submarine|Plongeur||6}},<ref name=g9>Garier, p. 219</ref> was ordered on 31 December 1906 from the Toulon Naval Base ({{lang|fr|[[Arsenal de Toulon]]}}). She was [[laid down]] on 4 April 1908 and was [[Ceremonial ship launching|launched]] on 14 September 1910 and began her [[sea trials|trials]] the following month. Initial testing of her powerplant was plagued by combustion problems that sent a lot of smoke and flames out the [[funnel (ship)|funnels]], but these were resolved before the submarine began her sea trials on 1 June 1911.<ref name=r5/> These were initially limited to performance on the surface and quickly revealed that the boilers produced only {{cvt|1200|kg}} of steam compared to the prototype's {{cvt|1600|kg}} because Maurice had altered the design of the boilers, reducing the amount of the sodium acetate/potassium mixture by over 20 percent and had changed the spacing of the boiler tubes which concentrated their heat in the center of the mixture rather than distributing it evenly throughout. Despite these issues, ''Charles Brun'' reached a speed of {{convert|13.6|kn}} from {{cvt|1098|PS}} on 21 May 1913 and had a range of {{cvt|1050|nmi}} at {{convert|7.15|kn|1}}.<ref name=g3>Garier, pp. 213–215</ref>

Submerged maneuverability of the boat was evaluated on 12 January 1912 and her turning radius ranged from {{cvt|280|to|326|m|yd}} compared to the {{cvt|190|m|yd}} of the ''Pluviôse'' class. The submarine made her deepest dive ({{cvt|25|m|ft}}) on 10 October and operation of the powerplant and her habitability underwater was judged acceptable.<ref name=g3/> Her speed and range while submerged was found to be totally inadequate: she reached a speed of {{convert|7.25|kn|1}}, but could only sustain it for 10 minutes, and had a range of {{convert|10.7|nmi|abbr=on}} at {{convert|2.8|kn}} versus the requirement for 100 nautical miles. Even using the electric motors, her underwater endurance could not be extended beyond about three hours because the Maurice boilers worked best when used at a high rate in a relatively short period.<ref name=r5/>

The Navy's Test Commission ({{lang|fr|Commission permanent d'Essais de la Flotte}}) assessed ''Charles Brun'' as unsuitable for active service with the fleet after her trials were concluded in August 1913 and began condemnation proceedings on 20 October after rejecting a proposal to replace the forward boiler with batteries taken from a decommissioned {{sclass|Naïade|submarine|2}}. Beginning in January 1914, her hull was stripped of most of her equipment, her engines were reused in the [[gunboat]] {{ship|French gunboat|Espiègle||2}}, and then [[ballast]] was added so it could be used in testing floating drydocks. When the First World War began in August, her conversion into a water tank for the naval base in [[Bizerte]], [[French Tunisia]], was proposed, but could not be performed because of stability issues from the earlier work. A contract was issued to [[Chantiers et Ateliers de Provence]] on 1 July 1916 to convert the hull into a water tank at their [[shipyard]] in [[Port de Bouc]]. The hull was there in September, but the conversion was probably not performed because she was listed as a submarine hull when she was finally struck<ref name=r5/> from the [[navy list]] on 7 June 1920. The boat was listed for auction on 13 November, but did not sell. It was sold to M. Saglia for 11,000 [[French francs|francs]] on 30 December and subsequently scrapped.<ref name=g9/>

== See also ==
*[[List of submarines of France]]

==References==
{{reflist}}

==Bibliography==
*{{cite book|last=Garier|first=Gérard|title=Des ''Émeraude'' (1905-1906) au ''Charles Brun'' (1908–1933)|series=L'odyssée technique et humaine du sous-marin en France|volume=2|year=1998|publisher=Marines édition|location=Bourg-en-Bresse, France| trans-title=From ''Émeraude'' (1905–1906) to ''Charles Brun'' (1908–1933)|isbn=2-909675-34-3|language=French}}
* {{cite book|last=Roberts|first=Stephen S.|title=French Warships in the Age of Steam 1859–1914: Design, Construction, Careers and Fates|year=2021|location=Barnsley, UK|publisher=Seaforth Publishing |isbn=978-1-5267-4533-0}}

{{WWI French ships}}

{{DEFAULTSORT:Charles Brun}}
[[Category:1910 ships]]
[[Category:Submarine classes]]