:
General Aviation Configuration Development Support
During
the past 20 years, Bihrle Applied Research (Bihrle) has supported the
general aviation industry during the development and certification of
numerous single and twin engine propeller driven aircraft as well as
business jet configurations. This has included static and dynamic wind
tunnel testing to provide aerodynamic data for configuration development
and analysis as well as for use in stall and post-stall behavior analysis
and simulation. These efforts include the calculating possible spin
modes with neutral and prospin/recovery control settings using three
degree of freedom methods (Reference 1). This methodology allows the
manufacturer to identify possible adverse deep stall and spin characteristics
concurrently with the wind tunnel testing. The acquisition of these
results early in the aircraft development process allows for on site
aircraft configuration changes that may be needed to improve spin/departure
behavior. The results are also used to brief the flight crews prior
to high angle of attack flight tests so they could properly anticipate
the aircraft flight characteristics during departure and recovery maneuvers.
For this particular test, Bihrle designed and developed the model, specifically built for the dynamic tests, and provided for any required modification during the tests. The resulting model was lightweight with low inertias that would allow the use of a high-resolution strain gauge
balance, optimizing the measurement of dynamic forces and moments.
The static and dynamic wind tunnel tests were conducted prior to flight test to acquire all of the data needed to analyze the normal flight characteristics, the high angle of attack characteristics of the candidate aircraft as well as calculate three degree of freedom spin modes.
Following analysis of the data and the calculations, an report was prepared for the customer that included analysis plots of all test data, a listing of all calculated spin modes with their parameters (angle of attack, turn rate, etc.), and observations and discussion of the airplanes
behavior in normal flight as well as at high angle of attack conditions. Further, the pertinent aerodynamic characteristics and their potential effect on departure, spins, and recovery were presented and discussed.
Armed with the knowledge from the dynamic testing and analysis, a highly successful flight test was conducted for the full-scale aircraft. From these wind tunnel results, the test pilot could anticipate what to expect from the aircraft during stall/spin testing. The flight test
results were in good agreement with the predicted results. Finally, this allowed the customer to efficiently and safely complete the high angle of attack flight test portion of the aircraft certification.
Reference 1:
William Bihrle, Jr. and Billy Barnhart, “Spin Prediction Techniques”, Journal Of Aircraft, Volume 20, Number 2, February 1983.
Other Dynamic Testing Success Stories
Boeing T-45 Goshawk Inverted
Spin/Spiral Mode and Hinge Moment Testing
Review
of Dynamic Testing SBIR Results
Boeing
F/A-18E/F Super Hornet Static/Dynamic Testing and Database Development
