Wind Tunnel Testing
The increasing availability of affordable computational resources has rapidly increased the usage and accuracy of CFD. An argument could be made that an aircraft’s drag and stability characteristics can be characterized via CFD as accurately and comprehensively as going to a wind tunnel. With that said, wind tunnel testing has some distinct advantages.
Testing in a wind tunnel allows for data to be gathered at a speed far greater than what is possible using all but the most expansive (and expensive) CFD resources. Numerous configurations can be rapidly tested and altered, and the flow can be visualized in real-time.
Optimum Aerodynamics has a variety of wind tunnel testing experience including powered model testing to simulate propeller effects and icing tunnel experience. We can provide assistance with wind tunnel and model selection, run log development, or data reduction.
Elevator angle required to trim at different CG and flap positions — wind tunnel data reduction
Stability and Control
Favorable stability and control characteristics are required for an aircraft to gain certification as well as positive pilot opinion. Aircraft stability and control must be considered at the beginning of a program as the conceptual design is established. Numerous inputs have an affect on stability and handling characteristics such as the desired loading envelope, empennage and control surface sizing and design, and power effects. A background in reversible control systems has increased Optimum Aerodynamic’s awareness of stability and control challenges that are increasingly often solved with fly-by-wire flight control systems. Some of our experience in this field includes:
- Longitudinal static and dynamic stability prediction and analysis
- Lateral / directional static and dynamic stability prediction and analysis
- Control surface effectiveness and elevator deflection required to trim
- Roll rate prediction (including aileron sizing)
- Hinge moment and stick force analysis
Optimum Aero has developed 3 degree of freedom (3DOF) models for both longitudinal and lateral / directional aircraft response. This can be used to characterize aircraft response to control inputs including damping frequency and period. See the data below which compares flight test and 3DOF model results to actual flight test elevator input.
Flight Test Data (green) and Simulation Results (blue)
Aircraft Performance
Optimum Aero has experience with performance analysis throughout all stages of the design cycle. In addition to cruise performance, rate of climb and field performance are also considered. Using equations defined in the Air Force Flight Test Engineering Handbook flight test performance data can be reduced to standard day conditions as well as expanded to any requested non-standard conditions. An accurate model of the propulsion system is required for accurate data expansion and reduction. Below are various performance analysis performed by Optimum Aerodynamics:
- Performance Prediction
- Cruise Speed
- Climb Performance
- Rate of climb
- Time, fuel, and distance to climb
- Field Performance
- Glide Performance
- Flight Test Data Performance Analysis
- Airspeed Position Error Correction
- Drag Model Reduction
- Performance Substantiation Reports
- Pilot Operating Handbook (POH) Performance Tables or Charts