TLG provides design, analysis and certification for new and modified aircraft and related aerospace products. TLG specializes in full vehicle analysis and optimization including static and dynamic loads, flutter, structural design and stress analysis, aerodynamic design, Computational Fluid Dynamics (CFD) analysis, FAA certification and aircraft performance and handling qualities.
Aircraft Design Cycle
Design, Aerodynamics, Loads, Flutter, Structural Design and Stress Analysis, and Performance are part of a total aircraft optimization design cycle. Aircraft design is an iterative process; early in the design phase, a loop around the design cycle may take only a few days or weeks. As the design matures and the detail increases, each additional loop may take months. When all the requirements are met, it’s time to build an airplane! A graphical representation of the design cycle is shown below. TLG can provide engineering services for many parts of the design cycle.
The design naturally starts with Design Requirements and Objectives (DRO); this is more than just saying “A jet aircraft that carries six people and goes 1250nm!” Along with size, performance and weights, the DRO should include cost objectives and certification requirements (a “cert plan”). From the DRO, the initial configuration work is done. TLG engineers have experience defining aircraft configurations (wing size, placement, control surface sizing, etc.) on a wide range of programs from small stability and control enhancements to complete, clean sheet designs.
Once an initial configuration is defined, the first loop around the design cycle can begin. In a sense, all information is needed at once; the aerodynamic analysis needs structure and weights data, while structural design requires loads, and loads analysis needs aerodynamic data! A trip around the design cycle will involve aerodynamics; a new set of loads which will change the structure and in doing so change weights, which then alters performance. After a trip through the design cycle, the results are compared against the objectives. Are the new weights and performance meeting requirements? Can the structure be manufactured within the cost requirement? Will the handling qualities meet certification requirements? This phase of conceptual design will usually involve numerous, relatively short design cycles as the configuration evolves to meet requirements.
The first big milestone in a program is typically Preliminary Design Review (PDR). At this stage, the Outer Mold Line (OML) and aerodynamics are mostly complete, and the initial design of structure and systems are sufficient to show that the aircraft should be feasible and meet DRO requirements. A much more intensive detailed design cycle follows between PDR and Critical Design Review (CDR). At CDR, engineering drawings are already being released, the structure and systems are mostly complete and the final weights and performance have been determined. At this point, changes to the design due to changes in loads or not meeting the DRO are very costly. At least one more design cycle is still needed for certification design which includes certification loads and performance. This cycle even continues up through flight test as the certification loads depend on flight test data.
TLG engineers have extensive experience in all phases of the design cycle. TLG is your source for aircraft design and analysis from conceptual design to final certification!