Helisafe TA: Helicopter Crash Protection
Occupant safety is and shall be a key design issue in the aviation market. Particular helicopters are highly complex systems, tricky to pilot, and often used for demanding missions in hostile environments.
Due to inherent risks in these operations and the complex manoeuvres close to the ground, there are still incidents involving helicopters. However, helicopter crashes should be survivable – they fly much closer to the ground and as such, the impact in a typical crash can actually be less than in a motorway car smash.
To date most of the work on helicopter safety has been concentrated on preventing technical failures and crashworthy design for airframe structures (absorbing elements in the sub floor, landing gear and seats). Nevertheless today’s safety equipment in helicopters still consists of passive harnesses and partly vertical energy-absorbing seats. Since crashworthy structural concepts are now well established, attention has been turned to increased occupant survivability in helicopter crashes based on cockpit and cabin safety through interacting advanced safety equipment.
Coventry University worked with partner organisations Autoflug (Germany) (Coordinator), Eurocopter SAS (France), Eurocopter Deutschland (Germany), PZL Swidnik (Poland), SIEMENS Restraint Systems, now known as Continental Safety Engineering International (Germany), DLR (Germany), CIDAUT (Spain), CIRA (Italy), TNO (Netherlands), Politecnico di Milano (Italy) and University Delft (Netherlands) on the European funded Helisafe TA project. The aim of the Helicopter Occupant Safety Technology Application project is to improve the survivability of occupants in case of helicopter crashes and to minimise the risk of severe injuries in both cockpit and cabin.
The Solution and Approach
The main focus of the project was to design for post-crash risks including those associated with operation over open water, rollover on ground impact, or operation in remote areas where subsequent rescue could be delayed. In all cases it was important to develop solutions that would mitigate injuries and enable occupants to leave the helicopter after a crash. The attention throughout was on the inside of the cockpit and cabin to with the aim to improve seats, harnesses and to consider and evaluate for the first time the use of automotive airbag technology in a civil helicopter.
The test programme involved three crash test dummies representing the pilot, a forward facing passenger and a side seated passenger. Full scale computer models of the helicopter and occupants were developed together with interior models of all three occupants and the safety concepts. Non destructive sled testing was performed using structural mock-ups for the pilot dummy and cockpit area at Siemens in Germany and for the passengers and cabin area at CIDAUT in Spain before final full scale crash tests were performed at the Italian Aerospace Research Centre (CIRA). Before and after tests were performed at all three sites to evaluate the performance of the new safety concepts developed during the project. The computer generated outputs from Coventry University were used to select the best harness designs and specify the pre-loads and firing times for the harness belt-pretensioners. The positioning and firing time for the airbag was also specified using the outputs from the Coventry University simulation work.
The project addressed the requirements to improve the mitigation of injuries and the chances of survival for the occupants, pilots and passengers, following a civil helicopter crash. Coventry University supported the programme of work with computer simulations to design and select occupant safety concepts involving seats, harnesses and airbags indepent of the size and weight of the occupants.
The computer simulation work developed by Coventry University provided the first successful attempts to model helicopter rollover and demonstrated the use of computer simulation using transferable automotive knowledge and methodologies to support a successful occupant protection development, test and evaluation programme in the aerospace sector.
The project partners benefitted through the demonstration of the effective use of computer simulation to support this programme of work. A new aerospace test dummy, in both hardware and software was developed within the project and fully validated using input from the Coventry University work to support the activity.
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