The development of ship–helicopter operating limits (SHOL) is fundamental to the ability of a helicopter to operate safely from the ship.

A SHOL trial aims to measure the impact of ship airwake, motion and visual cueing on helicopter performance, controllability and pilot workload across a range of sea, wind and lighting conditions.

The collected data is then used to develop safe operating limits for each intended aircraft operation for given aircraft masses and centre of gravity envelopes.

The scope of aircraft operations to be included in the trial and analysis should cover all intended operations on and to the ship under normal and emergency conditions by day and night, including the use of night vision devices.

At Prism Defence, we provide a full SHOL trial service from planning and conducting though to formal reporting. We also provide training and support to develop an organisation’s own SHOL trials capability.

 

Prism Defence conducts SHOL trials on the customer’s ship and aircraft under environmental conditions that are representative of the intended operating environment. Prism Defence tailors SHOL trials to meet:

• operational requirements of customers
• ship and aircraft availability
• required assurance levels

 

Prism Defence’s flight test professionals and supporting engineers are familiar with the demands of operating on naval vessels at sea under the most challenging conditions. We closely cooperate with the operational aircrew and ship crew to achieve the best outcome—safely and in the most efficient manner.

 

 

 

 

Before a helicopter can be cleared for embarkation on board a naval ship, rigorous analysis must be conducted to understand how much motion the helicopter can withstand on deck or in the hangar to avoid unsafe situations such as failure of restraints, damage to the airframe or sliding or toppling on deck.

 

Prism Defence has developed DeckSAFE, a bespoke suite of modelling and simulation tools, to provide an end-to-end ship motion limits analysis solution. The DeckSAFE physics engine is fully customisable, modular and includes the following key features:

• supports any helicopter configuration—single or multi-rotor, wheeled undercarriage or skids
• includes many of the most commonly used helicopter restraint and deck handling systems
• creates or customises simulation models to suit any shipborne application, deck handling systems and novel configurations

 

DeckSAFE has been comprehensively validated against a variety of experimental datasets.

 

DeckSAFE is typically used to determine ship motion limits for embarked helicopters, but it has also been used to analyse the safe carriage and movement of heavy vehicles and evaluate the efficacy of deck handling systems on naval ships.

 

Prism Defence’s ship motion limits analysis methodology can be used to:

• inform flight trial risk management
• optimise lashing configurations
• maximise operational capability
• perform incident investigations

 

Prism Defence’s engineering analysis team has a wealth of experience in conducting ship motion limits analysis across a range of aircraft types and operational scenarios to maximise operational capability and embarked safety for our customers.

COMPUTATIONAL FLUID DYNAMICS
 

The aerodynamic environment is a major contributor to the challenges facing operators when they conduct aviation operations in the vicinity of a ship. Air flowing over the ship’s superstructure, known as the ship airwake, generates turbulence, causes localised updrafts and downdrafts, and interferes with anemometer readings. Ship airwake can transport ship exhaust gases into the path of approaching aircraft.

 

Prism Defence uses state-of-the-art computational fluid dynamics (CFD) techniques to simulate ship airwakes, allowing our experts to:

• predict turbulence over the flight deck and helicopter approach path
• predict temperatures and exhaust gas concentration over the flight deck resulting from exhaust gases
• assess likely error of ship anemometer readings due to ship airwake effects
• assess the impact of changes to topside configurations and the effect that they may have on published ship–helicopter operating limits (SHOL)

 

Combining advanced turbulence-resolving models with an in-house high-performance computing cluster, Prism Defence can accurately predict aerodynamic features that might adversely affect ship–air operations.

 

Introducing CFD analysis early in the design or procurement cycle is highly cost-effective and provides:

• early and informed input to ship design
• optimisation of anemometer placement
• derivation of installed anemometer errors
• predictive risk management prior to the commencement of flight trials

 

Prism Defence’s in-house CFD capability is backed up by numerous validation studies and published academic papers. The CFD capability has been refined over many years to provide a robust and flexible solution which can be tailored to suit specific customer needs.

 

 

 

SHIP AVIATION FACILITIES DESIGN AND CERTIFICATION SUPPORT
 

Drawing on a wealth of operational experience, in-house technical resources and a resident body of expert knowledge, Prism Defence can apply its problem-solving skills to meet a broad range of ship–helicopter integration challenges.
 
Prism Defence can deliver independent and impartial operational and technical advice to assist customers with:

• defining ship-air interface requirements
• developing or evaluating tender responses related to ship or aircraft embarked operation capabilities and the design and layout of aviation facilities
• modelling and simulation to demonstrate requirements compliance
• quantifying technical risks
• addressing certification issues

 
The scope of delivery ranges from niche, task-oriented work packages to ship design consultancy and advice, procurement support and the planning and conduct of a complete flight test and evaluation campaign.
 
Prism Defence can advise customers how to establish an end-to-end process for the certification of ship aviation facilities. We offer a consultancy service that is unique in its field. It blends the inputs of operators, engineers and technologists to deliver solutions that support the customer in the delivery of full capability in the operation of rotorcraft from ships.

AVIATION PROCEDURES DEVELOPMENT
 

At Prism Defence, we develop bespoke embarked aviation procedures and associated documentation for our customers. Prism Defence is experienced in operating to single and multi-spot decks. We work with national procedures and regulations to design and deliver embarked aviation procedures such as:

• ship-helicopter operations manual (SHOM)
• ship aviation emergency procedures
• ship–air operation training manuals
• checklists

 

Prism Defence works with customers from a whole ship perspective to develop procedures to allow the safe and effective operation of rotorcraft by day and night, including emergency drills.

The development of the procedures can be linked to Prism Defence’s other services, including SHOL development and training for the ship and aircrew, providing an end-to-end package that will ensure the ship can operate safely and with full assurance in any environment.

 

 

 

 

Building on our extensive understanding of the multiple skill sets required to deliver organic helicopter or unmanned aircraft systems (UAS) capability at sea, Prism Defence offers full spectrum training in embarked aviation operations.

Our core expertise and practical experience let us deliver tailored, best practice packages that address all aspects of ship–air integration and operation.

In consultation with customers, Prism Defence develops and delivers courses that consider individual and team training needs to ensure safe, effective and standardised helicopter evolutions at sea. We will design and provide training for:

• pilot deck landing qualification
• ship’s aviation team
• flight deck teams
• emergency teams
• air controllers

 

Prism Defence delivers training at the customer’s premises and at sea on the customer’s ship with their equipment, ensuring the training is tailored and relevant. We work with customers to design optimal training packages that match requirements and available resources.