Ship and aircraft operators are showing an increasing need for
ship-based helicopter capabilities. For the military, the helicopter is
often regarded as a force multiplier, by extending the surveillance and
strike capabilities of the ship's weapon system. Other roles such as
medical evacuation, personnel transport, and supply support are common
to both military and civil operators.
Helicopters often need to land on ships in extreme environmental conditions, day and night. When coupled with combined effects of ship motion, turbulence, and visual cues, such operations can be both demanding and potentially hazardous.
These factors mean that the attainment of an effective capability is not a simple matter of flying a helicopter on to a ship. There are a wide range of practical factors that contribute to this capability, and a number of technical considerations that must be thoroughly investigated prior to going to sea.
Prism personnel have first hand knowledge flying helicopters and
commanding ships and therefore have a thorough understanding of the
complexity of the task, and the operational imperatives. In addition to
this understanding of the problem, Prism has many years of experience
in the science behind the complex ship-helicopter interface. This
unique combination of operational and developmental experience means
that we can develop operating limits that maximise the operational
capability whilst maintaining safety to an acceptance level; making
Prism the right choice for bringing a ship-based helicopter capability
A major focus of the ship-helicopter integration effort is often centred on the conduct of First of Class Flight Trials (FOCFT), which are also referred to as Ship Helicopter Operating Limit (SHOL) trials, or Dynamic Interface Trials. Prism are world leaders in the conduct of FOCFT, with Prism members having been responsible for more than a dozen such trials for the navies of Australia, New Zealand, Denmark and Sweden.
However, FOCFT are only part of the story. The diagram below outlines the myriad of activities and considerations that must be taken into account in order to realise a capability. A synopsis of each of these activities is detailed here.
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Ship Design and Certification
In order to ensure that safe and practical helicopter operations can be conducted to a given vessel, the ship’s flight deck (or helideck) and aviation facilities must meet a range of certification standards, national guidelines, and operator requirements. Prism has a thorough understanding of these standards and how they apply to different ship classifications. We make sure the standards are appropriate, and then conduct a facilities assessment to evaluate the flight deck and aviation facilities in accordance with these standards.
The embarked environment has unique characteristics, which must be considered prior to a helicopter operating at sea, particularly if the aircraft type has had little embarked operating history. Prism understands this complex environment and applicable aircraft certification standards, and is therefore able to work with the certifying authority to review compliance with these standards prior to embarkation.
Turbulence is an expected aspect of the embarked environment, but it can vary significantly between different ship types. Prism can employ modelling tools during the ship design phase to assist designers in reducing adverse aerodynamic effects over the flight deck. Once the ship has been built, Prism is able to use modelling, or conduct actual airflow measurements, to identify airflow characteristics that could cause dramatic handling qualities issues for the pilot, thereby serving to minimise hazards during the conduct of the trial.
Ship Motion Limits
One of the major analysis tasks that is conducted prior to embarking a helicopter onboard a ship involves dynamic modelling of the aircraft on the flight helideck, to determine when the unrestrained helicopter begins to slide or topple, or when the restrained helicopter exceeds a structural limit. This activity is commonly referred to as “Toppling and Sliding” analysis; although, because it also analyses the restrained helicopter, Prism refers to this as Ship Motion Limits Analysis.
Essential to undertaking such an analysis is DeckSAFE; a suite
of programs developed within Prism. DeckSAFE incorporates a time-domain
six-degree-of-freedom (6DOF) rigid body dynamics simulation, with
non-linear mathematical models to accurately resolve the physical
behaviour of an embarked helicopter.
Ship and Aircraft Instrumentation
Instrumentation is required for FOCFT to provide critical safety information for the test crew, and to measure trials data to produce accurately-defined limits. With our in-house, experienced design team, we are able to instrument both the helicopter and ship and provide a telemetry link to enhance safety and trials efficiency. Prism has the flexibility to develop an entirely new data acquisition system, or to integrate our specialised SHOL-development software to an existing suite.
First of Class Flight Trials
FOCFT involves the development of Ship Helicopter Operating Limits
(SHOL), and evaluating the suitability of ship aircraft interface.
SHOL are a group of defined operating limits for safe operation of a particular helicopter type with a given class of vessel. The limits are a function of the vessel’s motion and superstructure turbulence characteristics, and also the performance and configuration of the helicopter type. SHOL development involves operating the helicopter in a wide range of environmental conditions, commencing in benign conditions, with an incremental build-up. Proven processes are followed to determine the operational flight envelope and any unique procedures required to safely operate from the vessel. The aircraft and ship are usually instrumented in order to safely reach the maximum operating limits.
Other aspects evaluated during FOCFT include night lighting, landing aids, hangar facilities, aviation environmental sensors and displays, communications equipment, etc.
Embarked Aviation Procedures
Procedural documentation includes:
- Ships Aviation Manual
- Helicopter Standard Operating Procedures
- Emergency procedures
- Training Manuals
- Check lists
Training in embarked aviation operations is applicable to:
- Other aircrew
- Flight deck teams
- Helicopter control officers (HCO)
- Radar operators (if required)
- Ship bridge staff including Captain, XO, Operations officers and Bridge Watch Officers
- Emergency teams
- Fire fighters
- Rescue crews
- Ships medical teams
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