Click on the picture to enlarge it for a better view of the details.
       Bob Hoey explained his groups experiments with a variable geometry radio controlled bird model.  Bob was using the model of a Raven to accomplish the testing since the wing was less complex than that of other bird models types in his collection.
       Bob noted that the model was using a non-reflexed airfoil that required large trim elevator deflection so a better airfoil is needed.  The AC moved forward ½ inch with wing retraction but this was corrected with a minor linkage adjustment.  The wing structure is sort of awkward but strong, which is amazing considering the spar breaks.
      Above you can see the wing in both the retracted and extended positions.  Note the differences in the sweep angles of both the inboard and outboard sections.  The picture at the left shows the center section pivot at the trailing edge.In-flight wing movement required unloading the wing slightly to take the strain off the control rods.  Future models would use a jackscrew.  Bob noted that the concept worked with fast and fairly flat glides in both configurations.  However, there was NO obvious performance change with wing position.  More flight are needed before he would have a definitive answer on whether or not there were significant gains to be made for this reconfiguration system.
      Below are shots of the covered model with the wings in both positions.




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