The operational range and payload of the Merlin helicopters used by the Royal Marines have been significantly improved following comprehensive trials conducted with commando assault ship HMS Albion around the UK.

As a result of these trials, Merlins can now transport up to a dozen additional troops or, by carrying extra fuel, extend their flight time by an additional two hours.

This increased capacity could mean the helicopters operate further into hostile territories if required.

A Royal Navy press release stated, “Extensive trials with commando assault ship HMS Albion over the past few weeks around the UK – in good weather and bad – mean Merlins could carry up to a dozen extra troops or, with extra fuel aboard, fly for another two hours, which mean operating much deeper into hostile territory if necessary.

Since 2016, the Merlin has served as the ‘battlewagon’ of the Commando Helicopter Force, transporting up to twenty-four Royal Marines from ship to shore and around the battlefield. The helicopters also deliver supplies, ammunition, guns, and vehicles as required.

The performance metrics for safe Merlin operations, known as Ship Helicopter Operating Limits (SHOL), were based largely on data derived from the helicopter’s predecessor, the Sea King. However, with the Royal Marines transitioning to new Littoral Response Groups and an increased focus on raiding operations, it became essential to maximise the capabilities of the Merlin Mk4.

The press release detailed that “Tests years in the planning… were arranged on HMS Albion as she returned from her spring deployment to the Baltic.” The trials involved testing the Merlin’s performance under increasingly heavier operating weights and in different wind conditions, taking the helicopter into unexplored areas of the flight envelope.

In addition to enhancing future Merlin operations from HMS Albion or sister ship HMS Bulwark, the data from the trials is being examined to determine if the results can be applied to other ships and the submarine-hunting version of the Merlin, the Mk2.

You can read more about this by clicking here.

Tom Dunlop
Tom has spent the last 13 years working in the defence industry, specifically military and commercial shipbuilding. His work has taken him around Europe and the Far East, he is currently based in Scotland.

81 COMMENTS

  1. I just have to wonder if they can now carry more fuel and / or carry more weight then will that decrease the lifetime of the airframe ? In other words make them an Helicopter version ot the T23 Frigate ie flogged to death before a delayed replacement is in sight.

    • I don’t think the frame will be the issue.

      Neither the engines as there is sooooo much power there.

      My instinct it is that it will impact service intervals on everyone’s favourite gearbox!

    • This is an excellent increase in capability. It doesn’t mean they are going to fly so much longer on every flight, or have any adverse affect on maintenance. This is why they do extensive trials before release to service is given.

      • Exactly it’s a capacity that can be used but it’s hardly likely to be the norm I suspect though transferring goods between ships might be the most commonly used option I suspect.

        I am just surprised that it’s limits and capacity weren’t properly defined when in prototype form indeed I suspect they were, simply basing it on SeaKing parameters seems like more of an organisational matter, you know just continue using them i. the way they always have for years encouraged by being in peace time so no one could put in the effort and cost to bother to change.the rule book, manuals and all the support implications. Nice pr gloss mind to hide a certain element of complacency in not making what they already knew general and legalised practice.

  2. Good Day! Good news?

    Perhaps the Government will use this to reduce the numbers further?

    One question however, why is it not possible for all political parties to agree a sensible ( Funding over many years) at a level which is acceptable for all, to ensure proper security and planning for industry to have a secure footing. Also at a level that ensures a proper security for all cases ( Mad Vlad and others included).

    As it is this chop and change and cuts etc is a disaster!

    Nick presently in Hamburg

    • Sadly Nick, it’s not possible for our political parties to make a decision about who buys the drinks after hours.😉. Changing the subject slightly, could this improved Merlin be a contender for the NMH or is that too simple?

      • No mate. Merlin is not a “medium” helicopter!
        When I first set eyes on one at Boscombe many moons ago I could not believe how big it looked.

      • The Merlin is on the very large end of medium rotor at 32,000Ibs fully loaded ( standing room only it can carry 45 troops or 16 stretchers and medical team)…I believe the NMH is looking for something more in the region of 15-20,000Ibs fully loaded ( taking 10-15 troops) as some of the airframes it will be replacing are only 12,00ib fully loaded ( medium rotors range from that 12,000Ib up to Merlin size but they are simply very different beasts, even if all called medium lift rotors….there should really be a difference category for these very large generally navel rotors that don’t quite hit the 50,000Ib max takeoff weight that most people consider a heavy lift rotor..but are seriously larger that anything most people consider medium life (12,000-20,000 Ibs).

        • Thanks Jonathan. Puts everything into context. It was just a passing thought om my part thinking about commonality but I do get the weight issues.

        • yes. those gross weights are the standard metric and commonly expressed in metric tonnes
          Merlin HC.4 is 15 T class (maybe now higher )
          Wildcat is 6 T
          Chinook F is 22.5 T
          Seahawk is 8 T (maybe higher for latest R variant
          The old Sea King HAS.5 was 10 T
          The AW189 possibly for RAF is 8.3T

      • Policticans don’t buy drinks, thats the job for the donators and special interest groups. All parties can agree on that front.

    • Same thing applies to a lot of policies like key uk infrastructure, things like power stations etc.

      When multiple decade plans are needed it needs taking out of our short sighted self serving political system.

      • Would be good to buy some more HM2 airframes. I’m surprised the production line has lasted this long but upon the conclusion of the Polish order I doubt it’ll last much longer.
        With the massive expansion of the CHE facilities at Ashchurch they could dump some of the older airframes there. Even if only 30 airframes were kept in service it’d increase the resilience of the fleet.

          • I think they will be assembled by Kawasaki in Japan, i assume parts might came from all Leonardo group (Italy, UK, Poland even US)

          • there is also looking like a follow on order of 20+ more from Poland…to complement their AW149 order ( home built)…it’s interesting that a very discerning buyer like Poland ( who buy from the best deal…no matter the nation is buying the AW149 ( which gets a bit of hard press in this county)…what is really interesting is that they are also looking like they may buy a similar number I’d black hawks….so they are mixing their rotor fleet..from what I have read they seem to prefer the AW149 as an all round medium lift battlefield taxi and the Blackhawks for special forces work.

            where as the UK is moving the a one medium lift rotor does everything approach….

          • AW 149 have better space cabin config, nevertheless the most interesting is that Polish AW 149 will have Hellfire missiles.

          • That’s a nice to have on a utility medium lift rotor. The AW149 is a very nice medium lift rotor.

    • Peter wrote:

      “”Excellent but rather odd that the capabilities of such a mature platform are only being identified now””

      The UKs AW101 fleet were upgraded from 2014 onwards with:

      The Navy upgrading 30 to the MK2 standard (with an option for another 8 (not sure if that happened)) which would see new capabilities for the Merlin’s Blue Kestrel Radar and Sonar system; broaden datalinks; and upgrade the aircrew console and avionics, including large flat panel touch screens. On a tactical level, these improvements will enable 40 times the number of targets to be tracked compared to the Merlin Mk.1, improve submarine detection in shallow water, and enhance night operations resulting in far greater operational flexibility, and reduced lifetime maintenance costs.

      The Fleet Air Arms 28 Merlin HC3 battlefield helicopters updated to the Merlin Mk.4 configuration, which will include the same cockpit modernizations and obsolescence/ minor redesigns as the Mk.2, plus standard naval changes like a folding rotor head, strengthened landing gear, deck lashing points, and a fast roping point for the Royal Marines.

      • Evening Farouk.

        The other 11 HM1 beyond the 30 ( there were 44 originally, with I think 3 lost ) were not upgraded to HM2 standard.

        Many of us here called for them to also get the upgrade so that they could be the dedicated ASCS Sqn on Crowsnest, like what 849 NAS provided until that was disbanded with the withdrawal of Sea King ASCS7, which would free more Merlin for their main ASW task.

        The others were reportedly sitting around for some years and according to some here, cannibalised for spares, so alas that has gone.

        On the CHF Merlins, I thought the number to be converted for the CHF to be 25, not 28, which as you correctly state was the original number that the RAF had. 22 then another 6 bought in a panic by Gordon Brown from examples destined for Denmark, who quite rightly was getting flack for lack of helicopters in Afghanistan.

        He had also slashed the FABR ( Future Amphibious Battlefield Rotorcraft ) budget of some billions at that time too, FABR which was to be the Sea King Commando replacement until they just took the existing Merlin’s off the RAF and called them a “replacement”
        Effectively cutting numbers in the process, as the S Kings were I recall 33, though of course I assume the Merlin is far more capable than the elderly Sea King.

        • Evening Daniele,
          Whilst I can understand the frustration and anger felt towards the Governments penny pinching ways when it comes to the military. If we take a step back and look at the bigger picture we can see it isn’t just a British malaise (Note I am not defending the Gov or the other side of the bench)

          The May and July Issue of Air forces monthly have run articles on the Italian airforce and both mentioned the Italian holdings of the AW101. 30 in total , now what I found interesting is ata round the same time the Uk upgraded its fleet, the Italians purchased 15X HH-101A Caesar touted as the best version of the 101 going, the thing is, from what I can glean, the upgrades it received are no different to what the Royal Navy had done. Yes it has different higher rated engines , but from what I can see there is very little difference. The interesting part is in Oct 2021 a study was launched by the Italians to upgrade the rest of their 101 fleet to near the Caesar standard (not touching engines or airframe) as nothing has been done since they were purchased to upgrade them, the program started this Jan with an end date of 2031.

          That said they do own 98 NH90s as well as a load of others. Just surprised the PM isn’t that interested in improving ours, I mean he does like to travel on them every chance he gets.

          • Thanks for that, Farouk.
            They operate Chinook too I understand, but a much smaller fleet to ours.

            Swings and roundabouts, a look at Italy’s assets will reveal strategic enablers and assets that they lack.

            They, for some reason, desire helicopters in number, assume to support their industry?
            We know numbers are only a part of the picture. How many of them can deploy on operations, for how long, at what distance from Italy, and what logistic tail and experience do they have?

          • I was sent this the other day, its a link to the EDR magazine and goes back to Jan 2022. Well worth a buitchers you might like the March /April 2023 issue and its article on the booties

          • Italians have always have been a fan of helicopters, maybe the Da Vinci gene !? 😂

            They do have the weather advantage so it makes sense they invest in them. their FREMM(Aw101+NH90) and PPA(2 NH90) have space for 2 helicopters

            The HH101-Ceasar is a special ops helicopter plus pilot search and rescue one. so it is a very specialised bird.

          • Babcock is pushing a version of Arrowhead 140, with a larger hangar, that can take 2x NH90 size helicopters.

          • They deployed helicopters to Afghanistan, Iraq, Somalia and Mali.
            In Afghanistan there were A-129, NH90 and Chinook in small numbers.

        • Hi DM – great outline of the 101 orbat. I wonder why they did not, bring the stored airframes into service. Can’t be a lack of crew?
          With the diminished number of surface ASW ships, you’d think the RN would be keen to operate these helos as a force enable .

          Oh well, I’ll defer to the judgement of the upcoming Labour administration in 2024! God help us.

        • And another cheeky option for the RAF to consider. “40 + NH 90 , one careful owner down under. Looking to relocate for a good home – barks like a dog an loves to play dead! Loaded with that certain french design flair, temperamental and un reliable!

          Low on airframe hours, big on maintenance costs. Enquiries to the Australia Ministry of defence.

          • I read somewhere that NH90 is naff! It was considered many years ago for UKSF and rejected.

          • I did hear that it had lots of teathing problems, but it’s got a slightly smaller rotor diameter than the black hawk and yet is a bigger rotor with almost twice the interval load of a black hawk…20 seated troops vs 11…1500kg vs 2500kg. I think it probably cost a fair crack more though.

          • Hi DM. Unsure if you heard, an Aussie NH 90 went down in the ocean yesterday. 4 crew missing presumed gone. I feel terrible for posting my smart ares comment earlier.

          • Only read it on here. And I didn’t infer anything “smart arse” in your comment mate, so don’t bash yourself for no reason. Accidents happen. You know that with your experience.

          • Sadly one less ADF NH90 (MRH90) airframe available after one went down during night flying exercises for Talisman Sabre exercise off the coast of Queensland overnight.

            Unfortunately it looks likely that the four crew on board have not survived and while the search for the crew is ongoing it is now likely a recovery rather than rescue mission. RIP.

            The operationally troubled MRH 90 Taipans are ironically due to be replaced by 40 of the latest generation Blackhawks. The Taipan was originally acquired to replace the ADF’s early generation Blackhawks.

            Details of the cause of the crash are still forthcoming but night operations are inherently dangerous. The current incident mirroring the crash of two Blackhawks on night exercises in 1996 with the loss of 18 servicemen.

            The ADF will also prematurely replace the Tiger attack helicopters with 29 latest generation Apache helicopters.

            So you’re welcome to them.

          • Hi OZ. Sadly, the crash was the lead story on the National news here in New Zealand. Terrible tragedy and as I said to Daniel, I feel terrible for posting my earlier smart arse comment re the NH90. I do recall the two Blackhawks that were lost in ’96.I think it was a SAS night exercise?

          • No problem mate. You weren’t to know when you posted.

            The crash could have been much worse. The MRH 90 that ditched in Jervis Bay back in March had 10 personnel on board but a there were only minor injuries then. Its floats deployed and the airframe was recovered.

            The operational tempo of a massive exercise like Talisman Sabre is always going to pose risks.

            An American transporter carrying an Abrams MBT (not an ADF Abrams as originally feared) was involved in a 7 vehicle highway crash with civilian vehicles earlier in the exercise putting six people in hospital and sparking a bushfire.

            Hope the RNZAF NH 90 fleet continues to operate safely.

      • I knew some but not all of that. None of the upgrades really explains why the capacity or range enhancement is being tested now and not earlier.

        • Because NATO is at a heightened state of readiness due to Russia’s behaviour?

          If it had not been done earlier, I’m glad it’s being done now.

          Or…it is in part due to the LRG (N) and (S) plan which was not a thing before so not as much effort put into deploying RM Commandos from offshore assets at distance into the ME.

          AL Faw an obvious war exception.

    • Indeed I think in reality it was known, they would be known in design and testing just passed off by the relevant authorities to exploit those capabilities, but present circumstances and long term standard use backing up the potential has meant they are keen to get the most from each airframe as and when required. This is more about freeing up regulation on known evidence driven qualities.

  3. It’s funny these things take so long to arrange. When did the Mark 4s first get delivered? And wasn’t the Wildcat SHOL off the River class only tested last year from HMS Trent? I suppose these must be pretty complex tests.

    • Jon,
      The last MK4 was delivered at the end of last year:
      UK completes Merlin HC4/4A upgrades
      The UK has upgraded the last of its Leonardo Merlin HC3/3A (latterly the interim iHC3/3A standard) transport and assault helicopters for littoral use by the Royal Navy (RN) and Royal Marines (RM). The Ministry of Defence (MoD) announced the milestone on 2 December, saying all 19 HC3 and six HC3A Merlin helicopters are now at the HC4/4A Commando Merlin standard, and ready to support 3 Commando Brigade Royal Marines and other UK forces through to their planned out-of-service date (OSD) of 2030. “The 25 aircraft have been updated by Leonardo Helicopters under the Merlin Life Sustainment Programme (MLSP) negotiated by Defence Equipment & Support (DE&S), the procurement arm of the UK Ministry of Defence,” the MoD said. The Merlins were transferred from the Royal Air Force (RAF) to the RN Commando Helicopter Force (CHF) in July 2015, being delivered in a baseline HC3/3A ‘land’ configuration. Seven of these were then modified to the interim iHC3 configuration to bridge an operational capability gap between the retirement of the Westland Commando HC4s on 31 March 2016, and the introduction into service of the Merlin HC4/4A in September 2017.

      Maybe there lies the reason for the trials to take so long

  4. So do I understand this correctly…. The Merlin’s have been operating for the last few years under the Ship Helicopter Operating Limits that were set for the sea kings? Thus the much larger payload/weight/range/operational safety of the Merlin has been ignored and they have been flying way below what they were capable of performing?
    The increased range/performance quoted in the article, isn’t actually in reality an increase in the performance of the helicopter, it’s merely an increase in the SHOL?

  5. The Merlin fleet really does offer so much more that most other nations naval rotor fleets..and is a significant capability the RN and RM has..when you look at comparisons to the SH-60/MH-60 mix the US navy uses there is no comparison. A very very good set of navel rotors. A profoundly better ASW platform than everything else and as a medium rotor for amphibious operations it’s again profoundly better….unless you move to tilt rotor…

    • Jonathon, you probably know more on matter than me but I’d really like to see more Merlins in ASW & Crowsnest config ( T31s and T45s need way better asw than they have at present a a Merlin is a must for them in that regard). Even if it meant converting RM helos ( tho new build better). I’d like to see Blsckhawks for troop transport for RM and army as for that role I think Blackhawks are well proven and are easier to repair from battledamage compared to the more composite built Merlins.

      • With you on the BH, but for the NMH requirement only. I think it unrealistic we would be buying so many as to replace Puma and Merlin HC4.

        FAA has Drones planned for the “find” role to augment Merlin and also for ASCS to enable more Merlin to be used for their primary role.

        • Hi Daniele

          With Merlin I think there is a definite case for buying a few more airframes while the production line is still hot, after all the AEW role is not going away anytime soon and we really need an extra 6ish cabs to cover that role.

          • Morning mate.

            Indeed, I’ve suggested here before if I had a choice of more F35 or Merlin, I choose Merlin. That pinch point is greater, such is its capability and our pressing need for more ASW depth.

            And agree with your points above re Merlin vs BH for the CHF/RM too.

      • Hi old school for the RM and amphibious ops you do really want the range, payload and spare power the Merlin gives you over a more modest sized medium rotor like the Blackhawk..for example

        1) you only have a specific number of spots on on amphibious ships deck and you can only generate a specific number of sorties, so you want the maximum lift….a black hawk only carriers 11 troops, 2600Ibs internal or 9000Ibs…for a Merlin it’s 30 seated troops or 45 standing..6700Ibs internal or 12,100ibs external.

        2)Combat range of a black hawk is 320nmi combat range of a Merlin is 750nmi

        so as you can see each sortie from an amphibious ship or carrier using a Merlin can carry three times the troops twice as far as a black hawk…which is why for the RN/RM it’s the very best choice and a Blackhawk or any other 15-20,000IB max takeoff weight rotor is not so great…

        The final thing is a fully loaded Merlin can loss an engine on take off and not need to jettison anything onto a ships deck, if a two engine rotor like Blackhawk losses one engine on take off and it’s fully loaded it’s got more of an issue.

        You have to remember from the outset the Merlin was alway designed as a medium lift Naval rotor,its whole purpose is and focus is to be operated from the deck of a ship ( the Blackhawk was designed as a land based medium rotor…( as an example floatation never came into the design concept of the Blackhawk and floatation needs to be a primary concern for any navel rotor….you don’t want something with 30 troops on it sinking……Blackhawk has had a number of sinking events) .the best rotor for the marines is Merlin.

        • Jonathon. Thx for the reply – very informative. So BH for army and a few more Merlin for AEW and ASW. Too logical for MOD I suppose….

          • Yes around 6-10 more Merlin airframes to cover the AEW burden would be perfect…the product line is still open as well so it’s not even an issue..it’s just an off the shelf order of the best navel medium rotor out there ( it’s really hard to not go on about how much better Merlin is as a medium naval rotor than anything else.

  6. If you want maximum range out of a Merlin, you need new build, post US101 airframes + new generation engines.

    • No so with helicopters as they can easily but not cheaply- be rebuilt in a way winged planes cant.
      AH1 Apaches for Army are being rebuilt – with american engines and lastest electronics and new components
      The US Military has been rebuilding many types including Chinooks and others

  7. Could we not give our Merlins Refuelling capability ? although think am right that our CHF do not have this ability.Plus we don’t have deactied SF HEL like some of our European so called friends which have this ability.Think best bet is for the government to give us maybe 10 new builds PlZ but has ever 💰💰💰🙄

    • deactied” Dedicated? We do have dedicated SF Helicopters, though fewer than before, as 657 AAC was lost in cuts a few years ago and never replaced.

      Have a look at JSFAW “Joint Special Forces Aviation Wing” at RAF Odiham, which is a joint outfit of both the RAF ( 7 Sqn ) and Army ( 658 Sqn ) personnel. 658 is located away at Credenhill, 7 is at Odiham.
      I could point out which which hanger they occupy at Odiham, but best not.

      Not dedicated, but 815 and 846 NAS also support SF, especially in MCT as needed, while 1 AAC I understand has the SF Wildcat Flight commitment, while 664 Sqn of 4 AAC, who work with CRW Wing in CT Ops, provide Apache as and when required.

      The RAF Puma force has supported SF in the past, and I assume 33 Sqn still provides Puma for the SD Flight.

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