The current air vehicle design process has evolved to meet the needs of the manned system. Manned vehicles are very expensive to produce, spend a long time in service and have to be designed to be safe – particularly from the pilot's point of view. For these reasons the design process is also expensive, highly complex and takes a long time to complete.
Over the past 20 years the use of computer modelling has developed rapidly and computational tools are used extensively in aerodynamic and structural design and in the design and evaluation of the flight control system. So much work is now done in simulation that use of many of the traditional tools such as wind tunnels, structural test machines etc have been reduced to a very low level and, in some cases, has been removed.
However, the traditional approach to air vehicle design does suffer from a number of problems
- It is very difficult (near impossible) to compress the process into a shorter time period.
- It is very difficult to reduce cost
- In some important areas, e.g. aerodynamics, the physics used in the simulations is not accurate under the flight conditions and, therefore, there is excessive uncertainty in the predictions. This adds risk to the programme technically and financially.
- Many of the problems and issues that cause delays and cost overrun towards the end of a programme are the result of errors, etc introduced in the early project stage i.e. first 24 months. If better information can be made available in the very early stages, the whole programme can be better controlled
- Since design cycle times are so long, design teams do not get the opportunity to hone skills on a significant number of flying vehicles. The lack of experience adds to programme risk.
All these issues point to the need for the production of a flying vehicle at the very earliest stage in an aircraft, (manned or unmanned) programme. Until recently, this was impossible for manned systems. However, the development of advanced UAV capability makes “rapid prototyping” possible.