The UK Ministry of Defence intends to complete a study later this year that will determine the future requirements for its medium- and heavy-lift helicopter fleets, opening up the possibility of an acquisition of high-speed designs.

Under an operational analysis study, due to conclude by mid-2019, the defence ministry will look to establish the size of its future inventory and the capabilities of the rotorcraft within it.

Decisions taken as part of the assessment could see the UK opt to acquire a high-speed helicopter in the coming years.

Any such platform could replace the Royal Air Force's Airbus Helicopters Puma HC2s and the Leonardo Helicopters AW101 Merlin HM2s and HC4/4As operated by the Royal Navy.

In addition, the outcomes from the study will also influence the size and speed of a planned acquisition of Boeing CH-47 Chinooks.

Late last year the USA approved the potential sale of up to 16 of the tandem-rotor type to the UK, but London has yet to place a firm order.

Air Commodore Al Smith, head of air manoeuvre capability, says the analysis is being informed by the rise in state-on-state conflicts and the increasing need for sufficient aircraft available to project "as much combat power as we can".

Its remit includes the consideration of whether high-speed helicopters would address that need, as well as any requirement to operate in what Smith describes as "urban canyons".

But if the UK opts for a next-generation model, that would likely alter the number of helicopters needed.

"If we pivot towards a high-speed platform, that changes the force mix," said Air Cdre Smith, speaking at IQPC's International Military Helicopter Conference 2019 in London on 5 February.

Although not involved in the US Army's Future Vertical Lift effort, London has embedded officials in the programme office and is monitoring development of the two competing designs – the Bell V-280 tiltrotor and the Boeing-Sikorsky SB-1 Defiant.

Air Cdre Smith says the analysis began in the autumn and should conclude by mid-year. Its outputs will also enable the defence ministry to reach a so-called "main gate" funding decision for the Chinook purchase.

At present, the RAF has 60 CH-47s in its inventory, but the size of that fleet will also hinge on outputs from the operational analysis, says Smith.

But with the RAF's oldest airframes dating from the early 1980s, Air Cdre Smith points out that regardless of the eventual fleet size, new Chinooks will be needed if the service wants to maintain its heavy-lift capability.

Increasing maintenance costs and availability constraints mean that those elderly examples need to be phased out, he says, pointing out that they absorb three times the maintenance capacity compared with the RAF's newer CH-47s.

And, with one-third of the fleet having accumulated more than Boeing's recommended 10,000 flying hours, "there is a financial and availability cost in making sure they remain safe", he says.

Any new-build CH-47 would be delivered from around 2025, in line with the arrival of Boeing's Chinook Block II upgrade.

While the UK remains interested in high-speed platforms, Air Cdre Smith cautions that the two proposed architectures are still relatively immature – indeed, Future Vertical Lift is not yet a programme of record – which will influence the timescale for any purchase.

"Either you make a really early decision to jump, or you say I'm not going to do it in this generation; then you have to recapitalise [your existing fleet] in the interim.

"They are expensive programmes, so you need to be sure of the data before you jump," he says.