OSTIV Congress Day 3

Aeroelastic gliders; D. Eller and U. Ringertz

U. Ringertz

The first paper of the morning session was “Aeroelastic gliders,” presented by competition pilot, Ulf Ringertz. The presentation provided an overview of the strengths and weaknesses of the traditional flutter analysis. Details and difficulties of performing a ground-vibration test were also discussed. The inability to accurately determine the damping along with its very important role in determining the flutter of the flutter behavior of gliders was talked about. Suggestions and contributions of on-going work for improving flutter prediction were outlined. The ultimate goal of aeroelastic research is to address these issues already in the design phase of an aircraft rather than react to findings in flight test.

Examining Atmospheric Conditions for the Potential Exploration of Gas Giant Vorticities with Autonomous Gliders; R. LeBeau, G. Bramesfeld, S. Warning, C. Palotai

R. LeBeau

In the second presentation, Ray LeBeau discussed the possibility of using an autonomous glider to explore as giants such as Jupiter, Saturn, Neptune, and Titan. A glider mission could offer far greater horizontal coverage and duration compared to parachuted atmospheric probes. In addition, simulations and observations of the atmosphere of Uranus and Neptune indicate the possible use of updrafts in front of their dark spots, which are anitcyclonic high-pressure systems. First estimations indicate that a 100 kg glider could remain airborne in access of 33 hours of horizontal coverage.

Influence of aerodynamic and design parameters on sailplane performance in rough air; K. Kubrynski

K. Kubrynski

After the break, Krzystof Kubrynski presented two papers, “Influence of aerodynamic and design parameters on sailplane performance in rough air” and “Aerodynamic design of a flapped airfoil for high performance sailplane.” In the presentation, the cross-country performance of a sailplane was reviewed suing “static” thermal models, and then these results were compared with the performance of a sailplane in “dynamic” thermals. In particular, the influence of the lift-curve slope of the airfoil on performance was investigated. In the second part of the presentation, these findings were used to design an airfoil that takes advantages of the “dynamic” findings. After a number of “adjustments” to Xfoil to improve  the agreement between theory and experiments, a new airfoil was designed using a genetic optimization algorithm.

Design of a sailplane wing airfoil for boundary layer suction; L. Boermans

L. Boermans

The last presentation of the day was given by Loek Boermans who discussed current efforts of developing a suction airfoil for sailplanes. Suction airfoils have the potential in significantly reducing profile drag, which is the dominating drag contribution during interthermal cruise. Current natural laminar airfoils are reaching a limit with 95% and 75% of the chord having laminar flow on the lower and upper surface, respectively. The presenter showed his developments of using constant suction on the upper surface. The subsequent increases in performance have the potential of a standard class glider with a maximum lift-to-drag ratios in the mid 50s. The talk addressed issues of the integration of the suction system in the wing and possible fabrication approaches.

Note:
The senior authors have been requested to submit their papers to OSTIV’s quarterly, peer-reviewed, print and on-line journal Technical Soaring. The contact is Chief Editor Dr. Judah Milgram. Thus, soon you will be able to study the complete papers.