Achieving TRL 7
The aircraft concept was developed using traditional aerospace design techniques including Computational Fluid Dynamics and wind tunnel testing. A one seventh of length scale remotely-piloted model was flown to prove the design. The aircraft was taken from a design concept and scaled to a full scale prototype flight demonstrator during a US DOD funded programme titled the Long Endurance Multi Intelligence Vehicle (LEMV). Ground and flight trials of this full scale pre-production prototype aircraft were then used to validate the design and achieve TRL6.
The LEMV prototype was transferred to the UK following termination of the LEMV programme where further improvements and enhancements were carried out to return the aircraft to flight and bring it closer to production standard. In 2016 and 2017, the flight demonstrator aircraft undertook a series of flight trials in the United Kingdom (UK) conducted under European Aviation Safety Agency (EASA) approved civil aviation regulations. During these flights the aircraft was fully instrumented and the data gathered was used in HAV’s in-house developed simulator Flight Trainer Device to develop a comprehensive database of test and operational criteria. Moreover, these flights enabled HAV to gain extensive experience of operating and maintaining the aircraft on the ground in different conditions enabling the company to step confidently into a programme to achieve TRL8.
HAV has continued to learn and refine the aircraft’s design through hundreds of hours of simulated flight. With the prototype phase now complete, Airlander 10 is a de-risked platform and ready to commence the production aircraft programme. Plans are in place to work with customers to meet their specific requirements and to achieve a fully type-certified standard.
It should also be noted that while the aircraft airframe structure is innovative it is firmly based on proven technology. In addition, the systems and components used such as engines, flight controls and instrumentation will be produced to meet appropriate aviation production standards, thereby delivering a significantly lower risk for overall aircraft production certification and appropriate TRL.
Further Research, Test, and Evaluation Completed
Between the end of the LEMV programme and our return to flight in the UK, over 500 technical and production enhancements to Airlander were incorporated. These enhancements included introducing major modelling and flight control advances; developing gas modelling, sensing and management techniques; and characterised hybrid lifting body and buoyant lift control. Additionally, the propulsion system (engine power plant, propeller, and duct) underwent full integration testing in our test rig, which had been fully instrumented to aid the design and validate performance. Cumulatively, these actions and measures further matured the baseline design of the vehicle and flight testing expanded the flight envelope and provided the empirical data required to arrive at an optimal design.
As we gained experience and understanding of flying and operating the aircraft, further improvements were developed and incorporated. Ground and flight testing of the prototype Airlander in the UK included many months of operation outside in all weathers. In addition to allowing further development of the aircraft, this period allowed the development of improved ground equipment and maintenance practices to ensure that the production aircraft and its systems would be both robust and efficient.
Accelerated System Development and Aircraft Capability
We have built and maintain a fully-functioning Flight Training Device (FTD) which has proved of great value for pilot familiarisation as well as in the design, development, and performance modelling of the aircraft. The flight dynamics solver uses data from test flights, wind-tunnel experiments, engine rig tests, and empirical and design models to simulate real aircraft behaviour. Developed originally as a simulation environment for the study of aircraft flight characteristics, the FTD has now been further developed into a powerful tool that test pilots and flight test engineers use to practice, develop, and test flight techniques as well as to rehearse future test flights and normal and emergency procedures.
The FTD has been calibrated against results from flying the prototype aircraft enabling it to be used extensively as a tool to understand and validate the impact of design and productionisation changes, and to reduce the cost and risk associated with developing new capabilities. The FTD is also used to analyse data collected from test flights and to test design improvements before incorporating modifications onto the aircraft. The ability to modify the underlying models on demand has proved vital in assessing the effectiveness of potential design changes at the production aircraft refinement design phase.
We have designs and plans ready to move forward to production standard and LRIP. Having gained Design Organisation Approval from the Civil Aviation Authority (CAA), we will produce the aircraft to a CAA Type Certified standard which will meet the criteria for TRL8*.
*Updated 11th February 2021 to reflect new regulatory environment