Aircraft development: 40% cost savings possible
The regrettable failure of German OEMs such as Grob or Fairchild Dornier is partly due to the huge initial investments involved in the development of new aircraft. This is one of the most important cost saving potentials in aircraft construction, which v-plane engineering GmbH has addressed. The company demonstrates that cost savings of up to 40% can be achieved in aircraft development thanks to rigorous networking of the development environment.
As in all modern industrial sectors, the challenge is to push virtual development on the digital level as far as possible until the first prototype is constructed. And so the Integrated Design Process (IDP) was developed at v-plane. In this process, v-plane links all the necessary design disciplines such as 3D CAD Design, aerodynamic calculation using numerical methods, structural calculations harnessing the finite element method, flight mechanics stability analyses, structural tests and flight simulations. All EASA certification regulations are taken into account from the beginning in a database.
3D CAD Design represents the absolute foundation of all modern methods. Data of most customary CAD tools can be used with the intelligent employment of universal interfaces. Two CAD models must be provided, namely the model of the internal aircraft structure and the model of the outer shell.
Aerodynamic calculations are performed based on the model of the outboard wings. All flight conditions relevant for the approval procedure can be considered. The input parameters are angle of attack, angle of sideslip, flight speed, flight altitude, rudder and deflection flaps. Also non-stationary transonic effects such as jolts and the non-stationary flow separations induced by these effects are allowed for. The result of the calculations is all aerodynamic loads (forces and moments), which can be provided in further steps of the calculation of mechanical structures and the flight mechanics analysis. Also, optimizations are performed as part of the flow analysis. The focus is on optimization of resistance and of cooling air flows. The optimum placing of Pitot tubes and static pressure sensors can be obtained from further evaluations.
The calculations of mechanical structures are based on the CAD model of the internal structure and use the flow mechanics loads as external boundary conditions. The result is the zones of highest stresses and the associated safety factors. In further optimization steps, the structure can be strengthened in critical zones and mass saved in low-load zones. In the case of composite structures, the calculations result in the schedules of assemblies.
The flight mechanics derivatives – likewise obtained from the flow analysis – are further analysed and a check can be performed as to whether the stability criteria relevant for the approval procedure are fulfilled. The derivatives also serve as an input for the flight simulation, with which the behaviour of the aircraft as seen by the pilot is displayed. Rudder forces and moments for all flight manoeuvres can also be calculated – which also represent important input for the implementation of autopilots.
The EASA approval regulations serve as a basis for all steps, also for the definition of the critical load cases or the flight envelope which has to be verified. The results of all the intermediate steps relevant for the verification are stored directly in the certification database in the form of a report and are available to the CVEs and the respective authorities.
The certification database designed by Calin Gologan and Viorel Tigau contains all certification regulations and prescribes the necessary verification steps. It is a central management tool for the Office of Airworthiness and takes over the necessary controlling function in the approval process. The project status can be viewed at any time, and dislocated partners also have access according to their authorization. At the end of the process, a set of so-called approved data with which an aircraft can be built is generated.
The whole system was developed under the supervision of Calin Gologan and Dr. Volker Kassera. The system contains no data breaks thanks to the interfaces which have been created.
The results of all steps are checked with regard to certifiability, maintainability and production cost and iterated until a satisfactory result has been achieved for all areas. Only then does prototype construction commence.
The initial outlay is higher with this method, but the costs are recovered very quickly, as costs and time-consuming modifications to the prototype are avoided. The project risk drops considerably and development schedules and costs can be calculated.
To validate the IDP method, v-plane has as a sideline activity constructed its own four-seater passenger aircraft with the working name TR230, which will make its maiden flight in 2010. – Joachim Lau -
German Summary
Das bedauerliche Scheitern von deutschen OEMs wie Grob oder Fairchild Dornier ist zum Teil auf die enormen Anfangsinvestitionen bei der Entwicklung von neuen Flugzeugen zurück zu führen. Hier liegt eines der wichtigen Einsparpotenziale im Flugzeugbau, dessen sich beispielsweise die v-plane engineering GmbH angenommen hat. Sie zeigt: Durch konsequente Vernetzung der Entwicklungsumbebung sind Kosteneinsparungen bis zu 40% in der Flugzeugentwicklung möglich. Der deutschsprachige Beitrag ist nachzulesen auf www.aerotec-online.com
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