Wednesday, 13 October 2010

Super Merlin

The frontline British military helicopter fleet is currently highly fragmented.

Only as a result of difficult financial circumstances is this situation likely to change.

The Ministry of Defence can no longer afford to operate a multiplicity of types procured in small quantities at high cost.

Many of the older types are likely to be withdrawn without replacement.

The remaining types are likely to consist primarily of 4 newer helicopters which are currently in service or about to enter service.

These are the Apache,Wildcat,Chinook and Merlin.

The Wildcat and Apache fulfill the "find" and "attack" niche roles and consequently make up a minority of the helicopter fleet.

In future these roles may be taken over by other platforms due to technological developments.

It is unfortunate that army aviation is being pigeonholed into these roles.

These helicopters will not be discussed further here but more information on the Wildcat can be found in an earlier post.

The Chinook performs the medium/heavy "lift" role.

This involves transporting men,equipment and supplies.

The helicopter's "lift" role is essential to warfighting in low threat density/high terrain density environments.

The "lift" role can only be performed by helicopters and thus is likely to be the main role for military rotorcraft in future.

The Boeing Chinook is a particularly fast and efficient weight lifter.

It is far more expensive than a British Merlin but also far cheaper than the Sikorsky CH53K.

The internal dimensions of the Chinook are large enough to accommodate light vehicles used by British forces.

However,the Chinook has a number of negative points.

Although it's rotor is a similar diameter to that of the Merlin,it's twin rotor configuration gives it a much larger "rotorprint".

As the Chinook has wheels at all four corners of the fuselage,it also has a much larger "wheelprint" than the tricycle undercarriage Merlin.

This wheel arrangement also precludes parking the Chinook with it's tail protruding over the edge of a ship's flightdeck to save space.

The great and uniform width of the Chinook,due to it's sponson mounted fuel tanks,precludes densely packed parking.

The Chinook is not fully marinised and lacks features such as powered rotor folding,strong rotor brakes and negative lift which are important for operating on ships.

These problems do not preclude the use of the Chinook on board ships.

They do however preclude the efficient use of the Chinook on board ships.

Having even one large helicopter parked on deck with rotors spread has a negative impact on flightdeck operations.

As the United Kingdom has a requirement to deploy air mobile forces by ship,this is a major problem.

The Merlin can perform three primary roles:naval warfare;"lift" (transport) and search and rescue.

Despite the Merlin being a multirole helicopter,the naval warfare Merlin in British service is a specialised anti-submarine helicopter and the "lift" role Merlin of the Royal Air Force is not marinised.

Other countries operate multi-role naval and marinised "lift" variants of the Merlin.

A multirole Merlin could perform all of the Royal Navy's naval warfare tasks,eliminating the need for a naval Wildcat.

In the "lift" role,the Merlin is capable of most tasks but is limited in terms of vehicular lift.

The Merlin's fuselage crossection is slightly too small for vehicles like the Supacat High Mobility Transport (H.M.T.) series.

This is unfortunate as the width and height are only a matter of inches less than that which those vehicles would require for internal carriage.

It would not be a major technical challenge to build a larger fuselage but it would be challenging financially.

For the forseeable future then,Merlin is limited to external carriage of many light vehicles.

Unfortunately the weight lifting capability of the Merlin is less than the 7,500 kg gross weight of the Supacat H.M.T. and similar vehicles.

Merlin's useful load is 6 tonnes,more than the 5,500 kg kerb weight of the Supacat H.M.T.400 Jackal.

But that leaves little margin for fuel.

This problem can be easily resolved.

The Merlin has considerable growth potential.

Uprated engines and transmissions have already been flown on the Merlin and could easily be incorporated into new build helicopters.

With the B.E.R.P. IV rotors a Merlin has already flown at significantly increased weights:

"First flight on the dedicated trials aircraft (ZJ117),which is equipped with RTM322-02/8 engines rated at 2000hp,took place on January 12th 2007.

Trials flying concluded on 9th November 2007,which included an additional programme of flying in support of the UOR clearance. 

During that time the maximum speed demonstrated was 198 knots TAS,and the aircraft operated comfortably at a take-off weight of 16500kg (compared with 15600kg current AW101 maximum mass and 14600kg as the initial design max gross weight for Merlin Mk.3)."

The Rolls Royce RTM 322 has growth potential to 3,300 shp,well beyond the 2,300 shp of current British Merlins.

A minimum modification new build "Super Merlin" H.C. Mk.4,fully marinised with uprated engines,transmission and cargo hook,would be very well suited to British lift requirements on land and sea.

At present the only "lift" roled Merlins in British service are the Royal Air Force H.C.3/3a fleet.

It is currently intended that these helicopters be transfered to the Royal Navy for use in support of the Royal Marines.

However,despite being based on a naval helicopter design,these helicopters lack folding rotors and tails.

Making these helicopters suitable for maritime use will entail significant time and expense.

However,there is an alternative.

At present there is a requirement for new helicopters for use in the search and rescue role both by the armed forces and the Coast Guard.

It is currently intended that newbuild helicopters be purchased for the search and rescue role.

These helicopters may be civilian types.

Pilots trained to operate civilian helicopters will not be able to operate military helicopter types.

There is no benefit to military involvement in search and rescue if the helicopters used are not military types.

There is a justification for military involvement in search and rescue if the helicopters used for that purpose are the same helicopters the military uses in combat.

The Merlin H.C.3/3a helicopters do not have tail and rotor folding which they would require if they are to be transferred to the amphibious lift role.

However,a search and rescue helicopter does not require tail and rotor folding.

The Merlin H.C.3/3a could be converted to the search and rescue role as the Merlin H.A.R.3/3a.

This would free up funds to purchase new build fully marinised amphibious lift "Super Merlin" H.C.4s with uprated engines,transmissions,cargo hook and folding rotors and tails.


Chuck Hill said...

I like the way you think.

Now if the Brits would just form a military Coast Guard.

GrandLogistics said...

Hello Chuck Hill,

if some of the reports on the defence review are to be believed Britain is forming an armed Coast Guard.
They are calling it the Royal Navy!

I was hoping you would stop by as there was something I wanted to ask you.
I am guessing you would be familiar with the peculiarities of language used by coasties?
I read something by a U.S.Coastguard officer the other day and it sounded like gobbledegook to me.

I can't recall what it was now but it had something to do with a class of boat,maybe a 42 footer.
I will try to find it again and post it here if I do.


Chuck Hill said...

I haven't posted a comment for a while but I do stop by almost every day. Find your thought process refreshingly clear.

I hope someone in Whitehall is paying attention.