Sunday 1 September 2013

August 2013 Notes: Possibilities of Future RN AEW

Reason for writing:

Should it be Merlin, UAV or Osprey? As the E-2D is not an option with a STOL carrier design as has been built for the Queen Elizabeth class, how Britain can innovate its position into an advantage?

Key Words/Phrases:                                                                   

·         VSTOL: Vertical/Short Take Off and Landing, the cheapest system of carrier flight deck, but requires the most expensive aircraft… the Royal Navy (RN) was the first navy to employ this to provide its fixed wing airpower, but that was out of necessity when the first Queen Elizabeth class was cancelled (CVA-01 was due to have been called after the Queen) and all it managed to get built were the ‘Through-Deck Cruisers’ of the Invincible class.

·         CATOBAR: Catapult Assisted Take Off & Barrier Assisted Recovery, the system used on most major aircraft carriers, it allows for the widest range of possible aircraft to operate…but it is also more expensive to install and maintain than the VSTOL flight deck, although that is offset by its capabilities visa-vie aircraft operation.

·         STOL: Short Take Off and Landing

·         F-35 Lightning II (Joint Strike Fighter): produced in multiple variants, B for VSTOL and C for CATOBAR, this is the new stealth jet strike/fighter (what used to be called a Fighter Bomber…i.e. could fight its way to the target, drop its bombs and fight its way back) coming into service with the RN for the Fleet Air Arm to fly of the carriers.

·         Eurofighter Typhoon: Principle aircraft belonging to the Royal Air Force at the moment, a Cold War inspired Dog-Fighter that was used in conjunction with Tornadoes over Libya to do some limited bombing… although it was the much more venerable Tornadoes which had to aim the weapons.

·         NATO: North Atlantic Treaty Organisation – Britain’s principle strategic alliance,

·         AAD: Area Air Defence

·         UAV: Unmanned Aerial Vehicle

·         Surface Combatants: Corvettes, Frigates, Destroyers and Cruisers…the back bone of any navy these are the vessels which provide the presence/patrolling in peace, the task group fire power in war time and are essential to pretty much everything a fleet can be required by its government to do – sometimes is divided into Minor & Major surface combatants with the size split at ~5000tons.  

·         Aircraft Carrier: as defined by a paraphrasing of Admiral Caspar John (1st Sea Lord) -

o   An air field operating anything from thirty sixty to eighty aircraft; with the fuel, stores, fire-fighting equipment and so on which go with it.

o   A couple of batteries of heavy anti-aircraft defences with ammunition and control gear.

o   A minor Battersea Power Station.

o   A big radio transmitting and receiving station.

o   The radar, communications and other ancillaries equivalent to an RAF fighter sector controller.

o   Consider all the personnel (about two thousand) and accommodation wanted for these functions, then issue them all with three month’s provisions

o   Now put the whole lot inside a metal box eight hundred feet long by ninety feet wide, by about ninety feet high, make the box self-propelled and operate aircraft from the top of the lid.

o   There is your Aircraft Carrier.”[1]

·         LPH: Landing Platform Helicopter – like an aircraft carrier in terms of having a large flight deck/island configuration, but doesn’t carry fighter aircraft and concentrates on troop transport.

·         LHA: Landing Platform Helicopter/Attack – basically an LPH but with the ability to operate fighter aircraft of the VSTOL type.

·         LHD: aviation wise similar to an LHA usually, but as well as flight deck it also has a stern ‘dock’ that landing craft can operate out of allowing troops & heavy equipment to be sent ashore

·         Aviation ship: generic term used to cover any vessel where the primary method of functioning within it’s role is the support of aviation, i.e. aircraft carrier, LHA or LHD.

·         Radar Horizon = the distance at which an aircraft/ship can be detected on or traveling as close as makes no difference to the surface of the earth =  (2xHx(4Re/3)) [2]

o   The radius of the Earth used is 20,925,524.9ft, and is represented by Re.

o   Height of the radar above the surface is represented by H.

o   While every attempt is made to make the figures given as accurate as possible they are only general guides as there are some factors such as the transmitting radar's power, pulse length and Pulse Repetition Frequency, PRF, and the target echoing area are either protected information or unknown.

Figure 1. The Horizon…


Airborne Early Warning is not a luxury, it’s not even a benefit, it’s a necessity in modern warfare. With it task forces can see around the curvature of the earth; a crucial capability when facing sea skimming hypersonic missiles  or just low flying aircraft the earlier the detection the less the chance that anything unfortunate will happen.

It was a lesson re-learnt at a cost in the Falkland’s war, where there was no such capability; it having been lost with the retiring of HMS Ark Royal and her Gannets in 1978. It took two years after the war was over and lot of treasure for the current aircraft, (which are still in service currently) the Sea King Mk 7 AEWs, to be brought into service.  However, the Sea King was not a new aircraft in 1984 (in fact the Falkland’s War was where the ASW and Commando or ‘Junglie’ versions had proved their metal), so now in 2013 it is unsurprising that it is time for them to be replaced.

With this in mind a de facto replacement has emerged in terms of an updated version based upon the new medium helicopter stalwart off the RN, the Merlin. This presumptive direction of development however is not the only option and due the importance of this role to the fleet especially, but also to Britain’s armed forces capabilities as whole, it is worthwhile considering what other options there are.

Broadly speaking, and discounting E-2D Hawkeye due to the fact that the Queen Elizabeth’s are STOL aircraft carriers not CATOBAR[3], there are four options that conceivably offer a solution to the need for AEW RN:

·         Option 1: Merlin

·         Option 2: Osprey or AW609

·         Option 3: UAV

·         Option 4: Merlin & UAV

The trouble for all these options is they also have to advance on what is already acknowledged as an excellent capability, the Searchwater 2000 Radar having evolved to not only be able to watch the sea and the air, but also the land – proving itself a major asset in the war in Afghanistan, as well as Libya and countless other operations. 

Figure 2. Searchwater 2000 AEW Radar

Before getting into the analysis of the options, the aircraft’s ceiling or operating is going to be referred to a lot, because it’s important. The table below explains why; the high an AEW aircraft can operate at the better. For example the horizon difference between 30 & 20,000ft is nearly 40 Nautical miles; or 2.5x the Radar Horizon of the S1850M Radar that will be mounted 184ft up on the Queen Elizabeth Class Aircraft Carriers (now Radar Horizon is not the maximum range of detection, it’s at what point the curvature of the earth begins to interfere) – the highest mounted radar system in the fleet without an in service AEW system.

Height above sea level Ft
Radar Horizon in Ft
Radar Horizon in nautical miles
Difference in detection range to 20,000ft

Key Points:

Option 1: Merlin

The primary option; what is being actively pursued, 14 airframes have apparently already been allocated to be upgraded from the original ASW variant to and AEW version. The trouble is that there are two variants on offer. Thales are putting forward the solution of just transferring the Searchwater System from the Sea Kings to the Merlin’s – a solution which offers rapid turnaround perhaps ending the reality of an AEW capability gap[4]. However, Lockheed Martin are putting forward a system based around the radar that’s being used in the F-35 offering (at least theoretically) potential savings in logistics & training thanks to commonality and advantages in terms of capability. Unfortunately the Lockheed Martin is the missing dinner today to have a feast for lunch tomorrow option.

Furthermore, whilst any system might produce the better aircraft/better radar than presently in service, they are still limited in altitude terms by the lack of a suitable cabin space. Therefore making any improvement offered in reality less valuable as they will still be limited by the curvature of the earth.

Figure 3. Merlin Helicopter Plans
Figure 4. An Early Thales Proposal

Figure 5. The more recent Thales Proposal
Figure 6. The Lockheed proposal envisages pods on both sides of the aircraft

Option 2: Osprey or AW609

The alternative to a helicopter of course is a tilt rotor, and despite some popular assertions there is more than one option for that breed of aircraft. The primary option though is the MV-22 Osprey, an aircraft which has proved itself to an extent in combat but which also has suffered for the trials, tribulations and expenses of being the first tilt rotor aircraft to enter service. This has pushed up not only development costs but also implementation costs, because whatever theoretical points of similarity there are between helicopter’s and tilt rotors proved of less help. However, for AEW work the V-22 0sprey does have advantages, a 20,000lb internal carry capacity with an alternatively 15,000lb external carry capacity would mean it’s base design has the potential to be very useful as an AEW aircraft; it’s capacity and flight profile mean it could also make a very useful tanker aircraft[5]. However, at the moment it lacks a pressurised rear cabin – meaning before any conversion to AEW configuration (i.e. adding radars and the various control terminals inside the aircraft) to offer a meaningful advantage over a helicopter it would have to be pressurised. Whilst speed and range are great assets; an AEW aircraft isn’t a fighter - it doesn’t have to be fast, it does have to be stable… and the range that matters most is the detection range it’s radar provides, something for which ceiling matters more than anything else.

Figure 7. A V-22 Osprey at work

The Augusta Westland 609 is smaller, has less lift capacity and is in fact beaten by the Osprey in many ways, but it does have a pressurised cabin. Although it’s current ceiling is registered as the same as the Osprey it could conceivably operate at a higher altitude. However, for the UK this would be an even more expensive project than the V-22 Osprey as it would be the sole military user, and the requirements of military aviation in terms of protection & system redundancy are far more exhaustive – as is required by the fact that military aviation will likely as not come under fire with the intent of blowing it up, whereas civil aviation hopefully will not.

Figure 8. An AW 609 in flight

Tilt rotor aircraft are going to be a major feature in future wars, the V-22 Osprey already has been; they are certainly the vogue and in the future when the technology has matured they will offer dramatic advantages that will be definitely worth investment. However, at the moment as good they are, they are also expensive, they would add a further logistics train to the RN for a comparatively niche/role number (if they were being used to provide the replacements for the Junglies and an order of 60 or so airframes was made then it might be worth considering but as that is not the case…), and of course there is the fact that adding the aerodynamic intricacies of an enhanced external radar system to an aircraft that already fights with the laws of physics might well have very interesting results. This means that for the time being it seems sensible to put the option to one side… but it’s not the only option.

Option 3: UAV

A lot of trouble is being taken & money is being spent to build manned AEW aircraft (most importantly these are going to use up to 14 Airframes which could be used for troop transport or ASW or…), yet they replicate effort – the space in the back of a helicopter or plane is a confined replica of the command & control capabilities that already present (and has to be present) inside an Aircraft Carrier or an AAD. Furthermore flying an AEW helicopter is boring, requiring a high degree of attention for many hours doing a repetitive job.

Such a course of action therefore seems very strange in the light of recent developments with unmanned aircraft – especially that UAVs seemingly have not even been considered. An illogical finding considering that unmanned aircraft can fly higher than a manned because it’s lack of a pressurised cabin has no bearing; at a high enough altitude it might also work as a communications relay. It can hold position for hours without getting tired or bored, and most importantly in a world where needlessly endangering service personnel lives is increasingly frowned upon it would reduce exposure of personnel in something which by its very nature is very visible to the enemy.

There are two option sets the British Government could pursue either Rotary UAVs or Blimp UAVs; both of which would have advantages & disadvantages. Certainly from the perspective of the larger space offered by an aircraft carrier a Blimp UAV[6] which could fly higher, and stay on station longer would be very attractive. However, the general purpose utility of a Rotary UAV[7] - that it could be used to carry equipment, mount weapons or act as a scout – from the perspective of surface combatants this would be exceedingly useful, a force multiplier that would build on the ScanEagle that’s recently been brought into service[8].

Whereas in comparison to the increased manpower and increase cost of manned units (both in terms of £ and space – a finite commodity aboard ship); multiple UAVs could be used, with perhaps only one or two transmitting whilst others are just acting as receivers. This would have several advantages, for example if one of the transmitting units has to drop out of position for some reason, it can be replaced by just flicking a switch. More importantly stealth mainly works not by making the radar signals disappear, but by deflecting them away from the receiver; therefore the more receivers tuned within a radar network, the greater the chance of detecting an enemy stealth unit (whether it travels by air, land or sea).

Further to all this, there is not exactly a dearth of existing off the shelf options -maybe in terms of blip, in which case a search of the internet suggests a lot of work is being done on it but as yet no real working prototypes. In terms of Rotary UAV capable of carrying a equivalently powerful sensor suite to that proposes the Boeing A160 Hummingbird (has had some good results and has already worked with the Forester Radar system[9], but has also crashed), the Boeing Eagle Eye (was ordered then cancelled by the United States Coast Guard) and possibly the best on paper for ease of implementation the Northrop Grumman MQ-8 Fire scout that is already in service with the USN – with 27 of the 168 planned already operational[10]. The table over page allows for a quick comparison between these options and the two primary manned options.

Augusta Westland
AW101 Merlin
V-22 Osprey
Tilt Rotor
300knots (at 15,000ft)
20,000lb of internal or 15,000lb of external
A160 Hummingbird[11]
20+hrs (at 15,000ft – longest flight so far 18.7hrs)
20,000ft (limited by engine certification); capable of 30,000ft
Eagle Eye
Tilt Rotor
Northrop Grumman
MQ-8B Fire Scout[12]
5hrs (with 600lb load)
MQ-8C Fire X[13]
14hrs (with 600lb load)
E2D Hawkeye
Fixed Wing

Unmanned = Bold

There are of course many other UAVs but the criteria were that they should be available, and able to carry the radar, a mixture of other sensors and the requisite communications equipment. After that anything else would be a bonus.

Figure 9. MQ-8B Fire Scouts conducting operations aboard the USS Halyburton (FFG 40) during its second at-sea deployment[14]


Of these it’s the MQ-8C which would offer the best package available, procuring 24 to support the surface combatants (as currently planned Type 26s & Type 45s[15]) and a further 24 for Aircraft Carriers and ships of the Amphibious Task Group[16], would cost 48x $18.2million (fly away cost)= £562million – before the additions of radars, training and integration costs[17]. For that the RN would gain 48 AEW aircraft, or 48 long range scouts, 48 communication hubs, 48 gunships, and because the MQ-8C has been designed to assist with logistics 48 cargo-carriers[18].  The fact is the number put forward would be primarily for AEW but would also be more than capable when it came to other missions. They would provide every surface combatant commander with the option of putting up their own dedicated ‘all seeing’ ‘eye in the sky’ should they need to.  The radar and the sensors would be attachment, rather like the weapons containers in the stanflex system[19] could be taken in and out of service for maintenance without affecting the aircraft; they could be updated or modified just as quickly with no disruption to service. Under current circumstance this would be an advantage as it would make the choice of radar very simple – the current Searchwater system could be used until a better one comes available, retaining the value of the money invested in the Lockheed Martin system…but crucially allowing more time for it to be implemented.

Figure 10. A Boeing A160 Hummingbird carrying a Forester Radar system[20]


Option 4: Merlin & UAV

There are though some who will feel that taking back command and control to the carrier is a regression; well of course there is a middle way. A way which would still save precious Merlin airframes and protect lives on operations; this would again involve the sensor suite being carried aboard UAVs, but when a task group is instead of the data just being fed back to the carrier it would also be transmitted to a Merlin equipped to act as a Forward Airborne Control Aircraft (FACA); something which could be very useful when providing protection for a deployed land force or when it’s necessary to push the air defence network beyond Line of Sight communication range[21].

Such a scenario would actually make it far easier on the merlin airframes, as has been covered, the type and position of the sensor suite has offered many problems with the design therefore by taking that out, and instead increasing communication facilities and having more terminals to allow for both control of UAVs as well as to maintain situational awareness/direct the battle.

Advantages of this arrangement would be that escorts could benefit from UAVs, and the aviation ships would have a UAV/Merlin mix giving them a greater level of flexibility… instead of 13-14 aircraft being necessary, 6-7 could be used to provide these Forward Airborne Control Aircraft – only 2-3 would be required per aircraft carrier as they would not need to be operated continuously, but as required by operations.

A continuation of all this produces the option that the control systems could be palletised, along with the commando seats and the ASW systems; so that instead of the helicopters being assigned fixed roles, they would be able to be easily adapted to roles as required. Helicopters aboard aviation ships would under this circumstance no longer be pre-defined assets but would be adaptable units increasing the flexibility of the air group be orientated to provide the best capability for any operation. Therefore no longer would 16 helicopters be, 6 ASW, 4 AEW and 4 Commando, but instead would be 16 airframes. Airframes which in times of transit when the threat would be aircraft, submarines or ships could be 2 FACA and 14 ASW; yet in support of an amphibious operation these could be transitioned to 5 ASW, 3 FACA and 8 Commando – supplemented at all times by UAVs, UAVs which if the MQ-8C Fire X was procured would be able to act as sensor suite, gunship, scout and cargo-carrier.

Points of Interest/Brief History of AEW in RN:

·         AEW in the Royal Navy started life as binoculars and flairs in the hands of Observers flying in the backs of Spotter aircraft in the 1920s. This system was a tactical operational development by the RN and its Fleet Air Arm (FAA) in response to the limited detection range then possessed in the face of the growing speed (primarily, but also other capabilities) of aircraft; as well as the evolving capabilities of ships and their guns. In the pre-radar world this was the state of the art response; and it worked. During many exercises in the 1920s it proved its worth; it was not full-proof but it was a large improvement over the situation prior to its introduction. Whilst this was not the end of the British story; lack of funds and the focus of British technical development on primarily other applications means the next phase of its development was led by the United States Navy (USN).

·         The USN in World War II (thanks to new technologies, and evolutions in strategic thinking) faced a range of problems much the same as the RN did, baring one thing. The USN had an advantage over their transatlantic counterparts - whereas the RN had to face the world in order to protect an Empire and a Commonwealth which spanned it, the USN had to face just one ocean and just one navy, the Imperial Japanese Navy (IJN). This allowed for a specialisation of sorts to take place in their air arm; a wider variety of the types of aircraft to be carried in comparison to the consolidated RN air groups which were a primary feature of their response to their global commitments. Even with this and less completion for radar scientists, the USN actually ordered their first system, Cadillac, just eight months prior to the first Kamikaze attacks[22]. It was ordered with the intention of supporting operations as part of War Plan Orange. It was very basic, a Grumman Avenger fitted with AN/APS-20 radar.  It could detect small ships and aircraft formations at ranges of up to 100 miles; a substantial increase over the 30 miles a ship mounted radar was then capable of achieving[23].  It allowed fighters to be directed on to Japanese formations before they got within their strike range; increasing the chances of that attack never getting through.  It was a cornerstone of the Big Blue Blanket alongside the picket destroyers.

·         The RN was very covetous of this system, but unfortunately the war ended and the purse strings were tightened before they could acquire their own version. However, the post-war government of Clement Atlee declaring another 10 year rule to be in place; it was very unfortunate for them when just five years later the Korean War broke out in June 1950. So in 1951 the second ten year rule was discarded; the RN immediately purchased fifty Skyraider AEW aircraft from the US, and formed up 849 Squadron with the role of providing training, integration and every carrier with a flight of four aircraft. They proved their worth… so much so that the RN did not have to fight hard in the halls of Whitehall to justify their replacements.

Figure 11. A Flight of 4 Douglas Skyraider AEW of the RN
Figure 12. A Fairey Gannet AEW 3 flying over HMS Eagle.

·         Their replacements were Fairey Gannets, the first home grown AEW – although it did make use of the AN/APS-20 radars which had been fitted to the Skyraiders.  It was an aircraft and a system which once inspired an American pilot seeing it flying, to declare he had found God[24]. The Gannet was ungainly, but it did the job; whilst the RN had carriers capable of operating conventional fixed wing aircraft it gave them what they needed – warning, the ability to monitor the space around the fleet for hundreds of miles in any direction providing the RN with great operational security and flexibility. But, unfortunately, the 1967 carrier decision brought this to an end, with the big carriers and their air groups of AEW, Strike Aircraft, Fighters and ASW helicopters being retired from service as a cost saving measure. This was not though the end of AEW for Britain.

·         The Falklands war was a wake-up call, every single ship lost, as well as the on-going supply of the Argentinian forces by C-130s can be put squarely at the feet of lack of AEW. Without it the carriers had to operate further away from the islands, without it the Sea Harriers on Combat Air Patrol (CAP) could not operate far enough up-threat and were therefore always playing catch up to Argentinian raids, and without it ships on picket duty were exposed bastions – rather than providing a mutually supporting defensive line as the Big Blue Blanket of World War II had achieved. This is not to say that no ships would have been lost had there been AEW aircraft present; but it is very reasonable to assume far fewer ships and many less personnel would have been lost. Under these circumstances the current RN AEW system was born.

Figure 13. A Sea King Mk 7, the current fleet AEW, that has served with distinction & purpose in countless conflicts since it's entry into service, but most recently Afghanistan and the Gulf


In the current circumstance of defence it’s Option 1 which is the most likely to come about, probably the Lockheed Martin version as the actual spending of money could be put off longest. It’s not really sensible or practical in terms of force security but under the current economic climate it’s the Treasury which will most likely have the final say and they are watching the pennies very careful as the British economy is drawn back from abyss that Greece, Spain and other countries have fallen into. Which is a great shame because really its options 3 or 4 which should be chosen, option 3 would be very bold & brave and therefore is not a likely course of action.

However, option 4 where the UAVs could be employed from frigates, destroyers, auxiliaries – anything, just as long as they had the right pods aboard; therefore giving every vessel it’s own AEW protection, without taking up the space of an extra helicopter. The capabilities this would bring to counter piracy, counter drugs, the constabulary duties of a navy in ‘peace’ time would be amazing… it would be a massive force multiplication, still not allowing a ship to be in two places at once but would certainly multiply that ship’s area of effect. The Aircraft Carriers would be the ones to make use of the FACA as has already been espoused, able to provide forward of aircraft over a beach head or on-going land operation whilst the fleet operates many miles out to sea away from the problems of inshore waters.

The biggest difference Options 3 & 4 would bring though would be sheer numbers, if the situation arose that it was necessary then a Task Group could be surrounded by a ring of synchronised airborne radar, providing an almost physical barrier to any attack…or more likely mount multiple AEW surveillance flights over not just the Task Group but other strategic points within its area of operations. Allowing the Task Group to provide security & over watch for minimum effort, but achieving maximum impact.


Further Reading:




[1] (John 1987, 162-3)
[2] (Varshney 2002, Wolff 2011)
[3] And this is a shame because altitude of operation is key to how successful a AEW aircraft will be, none  of the rotary options can fly as high because of their lack of a pressurized cabin for the crew/passengers
[4] Which as the RN’s capability is based on helicopters, which can operate as well from the back of a frigate or an Auxiliary as they can from Illustrious or Ocean seems to be a pointless endangerment of British Service personnel’s lives
[9]‎ (11/08/2013) & (11/08/2013)
[10] In a further twist, Northrop Grumman have in partnership with Qinetiq offered to produce and unmanned Gazelle conversion in 2011, (08/08/2013)
[15] 13 Type 26s , 6 Type 45s & 1 Antarctic Patrol Ship, so it’s based on 1 per ship (apart from the last which will probably require 2 as its operating in the Antarctic), with some more for assignment to Auxiliaries functioning in an escort role – i.e. when a Bay class is sent drug smuggler hunting, or
[16] Based on each Queen Elizabeth being assigned 6, and the Ocean & Illustrious replacements being assigned 6
[17] Numbers of course would be different should more vessels be ordered, for example should some BMD type 45s fitted with (rather than for) MK 41 VLS for the SM-3 ABM system be built or a fleet of corvettes constructed with hangar space for the UAVs. &
[21] Although the other method to get round this would be satellite communications, the fact is that there are a growing number of ASAT systems in service and in development – and British communication satellites are in a public/private partnership which makes them very expensive to use.
[22] (Gibson 2011, 7)
[23] (Gibson 2011, 7)
[24] (White 2009)

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