Analysis Turkish Type Fast Attack Craft (TT-FAC, TTHB) Project in a nutshell

The Turkish Type Fast Attack Craft Project (Türk Tipi Hücumbot - TTHB, in Turkish), also known as the Next Generation Fast Patrol Boat Project (NG-FBP) of the Turkish Navy, first appears in documents published by the Undersecretariat of Defence Industries (now the Presidency of Defence Industries) in 2008. The aim of the project is stated as;

"Meeting the future needs of the Turkish Navy, providing the design of a new FAC to replace the ageing classes".

NM = Nautical Mile
BS = Beaufort Scale
FAC = Fast Attack Craft
FPB = Fast Patrol Boat
LOA = Length Overall
LWL = Length Waterline
DWL = Design Waterline
GT = Gas Turbine
DE = Diesel Engine
RG = Reduction Gear
EW = Electronic Warfare
EA = Electronic Attack
ED = Electronic Defense
IR = Infra-red
AShM = Anti-Ship Missile
SFOC = Specific Fuel-Oil Consumption


Background to the TTHB project and the early stages of the Request for Information (RFI) issued by SSM​

The Turkish Navy's first inclination was to acquire a Fast Attack Craft solution based on a composite structure that offered a light structure, naturally low RCS and IR & Acoustic signature, and armour protection by Kevlar that could be easily upgraded. Yonca-Onuk, manufacturer of the MRTP (Multi-Role Tactical Platform) series of boats, was the first choice. But this trend didn't last. The initial plan was to acquire at least 6 boats with 4 options (expected to grow to 15 over the years), in the 200 to 300 tonne range, with limited endurance but rapid strike capability. In addition to the rapid strike capability, TN has required this boat to have cruising capabilities in excess of 300 NM operational range at maximum attainable speed, minimum 60 knots, in Sea State 3 in BS.

The weapon and sensor configuration was listed and kept pretty much the same throughout the evolution of the design.​
  • 3D search radar and Guided Missile - Point Defense system​
  • Basic EW suite, R-ESM and limited EA capability​
  • 40 or 76 mm main gun, the tendency was for 40 mm fast forty.​
  • 4 or 8 Harpoon sized AShM​
The first designs that appeared will be skipped in this article, soon after the appearance TN shifted their focus towards more capable and high endurance platforms, this was the point where the public met with Anadolu Shipyard's Ada Class spin-off (Although it was not based on the Ada Class design, the features and lines were adopted from); an offer for the TTHB project that was widely acclaimed by the public. The designs submitted in response to the request for information issued by the SSM were now above 400 tonnes to meet certain requirements in terms of accommodation and endurance. ADIK's design had a displacement of 800 tonnes, WJ based propulsion, with 5 gas turbines; 4 x LM500 + 1 LM2500, the latter only for booster configuration, driving a single WJ, while other 4 GT's drive 2 WJ, 2 GT for each WJ. It has topped 60+ knots, with a displacement type of hull operating in semi-planning regime supporting its dynamic stability. It was not a FAC, however, can be assumed as a Corvette at this size and completely unaffordable.

adik-fac-jpg.52


The design features a low RCS platform with embedded (not pop-up) AShM launcher by directly adopting the Ada class mast with ESM module and 3D search radar. In addition, other designs from the same design office were made for other shipyards, briefly Desan, Sefine, Istanbul Shipyard. But the other eye-catching design(s) were the 2 different offers from RMK Marine. The propulsion system of these designs has not been made public, but it can be assumed that the design on the left used 3 waterjets (possibly GT-COGAG), 1 in booster configuration, and the one on the right used 2 waterjets, both powered by twin engines on each WJ (GT + GT COGAG).

rmk-tthb1_2-jpg.54
rmk-tthb2_2-jpg.55

One of these designs is focused on providing an integrated mast, a solution offered jointly by RMK and Aselsan with an APAR-based 3D search radar, pop-up AShM launchers (left or top image), and the other is focused on providing a novel design jointly by RMK Marine and a foreign partner (Design Solution), focused on a modern semi-catamaran hull form with integrated main gun and pop-up AShM launchers. Judging by their size, these designs were in the 450-600 tonne displacement range, and at the time were outside the Navy's specified range.

Another offer came from Dearsan, a solution based on the novel YTKB design, with increased capacity and high speed profile. The main propulsion was COGAG.

dearsan-tthb-jpg.56

So far, the scene has been dominated by platforms with a high visual profile (with the exception of Dearsan), as opposed to what TN was seeking; the ability to operate in the Aegean Sea with a low visual, IR profile in addition to low RCS, as these FACs are more likely to be targeted by anti-tank missiles as well as coastal AShM defences. Only Dearsan's platform came close to a low-visual profile, but failed to provide sufficient technical details on IR and RCS signatures.

Then STM, a company affiliated to SSM, proposed a new design, somewhat knowing what TN was looking for, a new design with extremely low RCS as well as very low visual profile with small DWL (less than 1.5 metres) and overall depth, FAC-55. It should be noted that from the outset the TN had an abrupt speed requirement, initially over 60 knots, later updated to 55 knots as the size increased. This speed range is only achievable with all-gas turbine propulsion and water jets for this size of platform. STM's FAC-55 was powered by 3 Rolls-Royce gas turbines, each driving a waterjet, giving a total of 28 MW of installed power (note that the Ada class is equipped with 32 MW of installed power), one in booster configuration, the other two in steerable condition.

stm-tthb2-jpeg.47


There were no comments on which design was chosen, but TN has signed a Concept Development Project, Phase I with STM in coordination with SSM (SSB). In this phase, the concept of FAC-55 has been studied in detail with certain modifications, towing tank tests have been carried out both for resistance in calm sea and sea state 3. In addition, STM carried out the preliminary signature studies and assessed the design for applicability. TN made requests during Phase I and the displacement of the vessel has increased continuously, reaching a point where the hull is no longer able to meet the 55 knots requirement at 3 GT, resulting in an update of 50 knots.


Project updates from 2021-2022​

Phase II of the concept development project was signed with STM in coordination with SSB. As the Conceptual Design Phase I was completed on a platform based on the FAC-55 design, the Turkish Navy had introduced new requirements for accommodation and installed equipment. This has rendered the FAC-55 design obsolete and STM has started studies on a new design for the Contract / Functional Design phase. In the first half of 2021, the new design has started to take shape, a platform more capable on the capabilities with the sacrifice of the visual profile and the maximum attainable speed. The latest iteration of FAC-55 was known to be over 550 tons with a maximum speed of 50 knots in sea state 3, while the maximum attainable speed was not disclosed but expected to be above 55 knots. (5 knots less than the first iteration). STM has in fact presented the design philosophy of the TTHB through the MPAC platform. First shown at IDEF'21, it then took its place on the STM website as of Q1 2022, repeatedly marketed by STM at all conferences and exhibitions and to special foreign customers - visitors. A new multi-purpose attack platform with almost the capabilities of a Corvette with optional growth space. After a personal engagement with STM's engineers, we have found out that the MPAC design is in fact not the TTHB itself, but it is TTHB with a "make-up" where the visual appearance has been altered to avoid possible licence issues with the TN. Little is known about the TTHB as of March 2022, but it is safe to say that MPAC is what the TTHB has become in terms of design philosophy. This information is based on insider knowledge.

1646401934733.png


The main differences are as follows.​
  • COGAG propulsion (3 WJ -> 3 RR GT - 28 MW) was replaced with CODAG design (3 WJ -> 2 LM500 GT + 2 MTU DE - 18-20 MW)​
  • Increase in the range, +30% range and higher cruise speed compared to the latest FAC-55 iteration​
  • More growth space and larger mast, with additional spots​
  • Conventional lateral AShM bay, compared to the forward-looking pop-up launchers utilized in FAC-55​
  • Increase in the Draught, thus resulting in a more efficient hull form​
  • Additional Deck with increased accommodation and space for the consoles and the equipment​
  • Additional FCR, increasing situational awareness​
  • Simpler and straight forward design, with affordable and easy to maintain propulsion system​
  • Reduction in the total price, nearly as 40% in overall design​
  • New design with the double endurance, better sea-keeping features, more provisions to stay longer at the sea​
  • Larger AShM Bay that can optionally be equipped with 12 Medium Range AShM, or Combination of 6 MR + 4 LR AShM, or 4 LACM + 4 AShM​
  • More electricity capacity, 35% increase in supply, thus indicating better EW, sensor suite​
  • Better EW suite, both R-ESM and C-ESM are now available, also Compact ED/EA system being developed by Aselsan is now seen on MPAC, so available at TTHB​
The updated 3D search radar was not listed among the differences, as the same radar was also planned to be used on FAC-55, an X-band based radar (as of the current choice, may change later so take it with a pinch of salt).

In summary, TN has abandoned the FAC-55 design in favour of the more conventional and flexible MPAC design, which, despite being an unfinished and untested design, has managed to attract several customers because it can be easily configured in different roles for different missions, including OPV and patrol boat roles, FAC roles with different payloads, flexible propulsion options thanks to the larger engine room and the ability to overhaul on site if necessary, with a comfortable engine room. We have also delivered the FAC-55 design was not a chosen design at the beginning of Phase I as TN has a habit of being involved in the projects and managing how the design evolves, by April-2021 in this forum. This information was confirmed by Nihal Yalçın, head of the Electrical&Electronic Integration Team of the Naval Platforms Division at STM, in a speech given at STG'22 organised by ITU-SAVTEK. In conclusion, we say that TTHB will be MPAC with minor differences on the outer shell, which meets the certain requirements for TN, protecting the core and the main features in dimensions, displacement, sensor-weapon payload, propulsion system et al same. Both SSB & TN have also agreed to work on 2 different TTHB designs, with several different features, while keeping the concept the same, with alternative systems for redundancy - something SSB applies as a principle with increasing numbers of unexpected embargoes.

At the end of the TTHB project, both STM & SSB & TN will hold design rights to 4 available platforms, namely FAC-55 (3 iterations in concept design phase), MPAC (completed contract & functional design phase), TTHB1 and TTHB2 (completed contract & functional design phase).​

TN still interested in high-speed strike capability, what next?​

Again, TN is still persuaded that it has a fast strike capability, but an MPAC-like platform can only deliver 40 knots speed with an efficient SFOC, 45+ knots speed with a manageable SFOC, and may have a maximum of 52-53+ knots achievable speed with an unmanageable, inefficient SFOC, but in all of these it has a longer operational range than the earlier FAC-55 design. TN still requires a platform capable of 60-65+ knots with affordable, reliable propulsion and capable of carrying at least 4 or 8 harpoon-sized AShMs. As a final note, here are the two options under consideration for now.
1.Yonca-Onuk's recently unveiled MRTP 51 design

The MRTP 51 has a maximum speed of 55+ (60+ in extreme cases) knots using diesel engines alone, with a highly manoeuvrable composite hull design. This is an update of the MRTP 49 design previously submitted to the TTHB.

img-20210818-wa0104-jpg.28752


2. Unmanned surface vehicle design, unknown, capable of carrying AShM missiles.

The design requirements for this have not been made public, but TN has made certain requirements for the TTHB design, certain capabilities to work with USVs (alternate console position, increased power and accommodation for operators, etc.). However, a USV design can easily be used for rapid strike actions in coordination with a more capable central communications ship. A USV would also easily reach speeds in excess of 60 knots, have a longer endurance than a manned platform due to the lack of crew on board, and could optionally be manned with a minimal crew to operate weapons and navigation.​
 
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Anmdt

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It is rapid respond platform with extra agility, and due to the its size, it fits perfect for ambushes. Sometimes you need to go and verify an event by eye or other SIGINT measures, close up before making a decision.

There were reports of FACs that can entrail large ships without ever being detected, especially when the sea state is 3+ the waves cause a clutter and noise on the radars that helps properly designed FACs to move around unnoticed.

However, nowadays they are more of an upgraded patrol boat with high speed and extra agility and soon other duties will be left to USVs.
What are your latest insights into the Admiral's statements? To be honest, I was amazed, I used to hear things the other way round.

Are we going to see an upgraded MPAC with a more powerful propulsion system? Or are we going to see a rollback to a FAC-55 like design?

I have merely speculated that MPAC may meet 45+ knots requirement @Sea State 3.
 

Anıl Mert Taşkın 

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What are your latest insights into the Admiral's statements? To be honest, I was amazed, I used to hear things the other way round.

Are we going to see an upgraded MPAC with a more powerful propulsion system? Or are we going to see a rollback to a FAC-55 like design?

I have merely speculated that MPAC may meet 45+ knots requirement @Sea State 3.
We're all waiting for the outcome of the latest design revision. At this stage it can be said that the design has been slimmed down, in contrast to what the Navy had demanded previously, and is leaning towards a more agile platform that can form "wolf packs" with USVs. One thing we can be sure of is that there won't be any disappointment. We will see a transitional form that will represent the future of unmanned platforms in FAC formation.​
 

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