Another important aspect of signature reduction is infrared (heat). Let’s take a closer look at this.
The first aspect that jumps out is the pair of diesel exhausts located on the ship’s sides, just above the waterline as seen in the photo below. Note the discoloration around the exhausts. On a side note, the various ‘camouflage’ schemes (it’s not really – it’s just a crew ‘feel good’ paint project) that have been applied to the ships all make a point of painting dark black around the exhausts as a means of hiding the exhaust stains.
|Diesel Exhausts Low on the Hull, Marked by Stains|
|Diesel Exhausts Covered by Black Camouflage Patches|
From a combat design point of view, the location of heat sources, in the form of the diesel exhausts, near the waterline invites hits by heat-seeking missiles at the waterline which is the worst place to have a hit as hits in that location have a high probability of causing flooding damage. Given the LCS’ minimal manning concept and survivability design intent to abandon the ship upon receipt of a significant hit, placing heat sources at the waterline all but guarantees the hits will be significant and the ship will be lost.
The one unknown aspect is whether the diesels would be operated in combat. The diesels are used for ship systems power and can be cross connected to the main propulsion system, as well, so I assume they would be operated in combat but I don’t know the combat power management scheme so I can’t say for sure. If the diesels are not used in combat then this is not a vulnerability.
The other source of heat is the exhausts from the ship’s turbines. For the Freedom variant, four 750-kW Fincantieri Isotta-Fraschini diesel generators provide 3 MW of electrical power to power the ship systems, according to Wiki. For newer Freedom variants, Fairbanks Morse has been selected to provide two 16-cylinder Colt-Pielstick PA6B STC diesel engines that will deliver 12 MW of propulsion power. (2)
Note the location of the main exhausts, circled in the photo below. From a combat design perspective, this is problematic since the exhausts are located within 20-30 ft of the ship’s main radar, the TRS-3D/4D. Thus, a hit by a heat-seeking missile on or near the main exhausts will almost certainly destroy the ship’s radar which provides the targeting for the ship’s only air defense, the short range AAW missile defense RAM launcher.
|Main Exhaust Location Near Radar|
The exhaust location, essentially, invites the destruction of the ship’s only AAW defense.
This post is somewhat speculative in that I don’t have any data on the ship’s actual IR signature but it’s not much of a reach to believe that the main exhausts and the diesel exhausts, if they’re used in combat, are the primary point heat sources. As we noted, the location of the main exhausts relative to the ship’s radar is problematic. For a ship that was supposedly designed with significant signature reduction in mind, the main exhaust location is puzzling and suggests a design philosophy that is not focused on combat. As noted in many other posts, this tendency to design warships without a focus on combat is as well entrenched as it is misguided. All of this is just one more bit of proof that the LCS is not, and cannot be, an effective combat vessel.
(1)Naval Technology website, “US Navy’s LCS 4 completes main engine light-off”, 29-Oct-2012,https://www.naval-technology.com/news/newsus-navy-lcs-4-completes-main-engine-light-off/