Linda S. Ellis
Helicopter Model Tested in Icing Conditions at NASA's Lewis Research Center
Cleveland, OH -- Icing studies that may result in major improvements in predicting helicopter rotor performance in icing
conditions were recently completed at NASA Lewis Research Center's Icing Research Tunnel.
A 1/6th scale Sikorsky Black Hawk Helicopter model was tested for ten weeks, over a wide range of icing conditions and critical
forward flight conditions.
The testing by NASA, the U.S. Army and Sikorsky Aircraft, Stratford, Ct., was focused to expand the experimental database as well
as develop reliable methods to reduce the cost and time required to certify civil helicopters for flight into forecasted icing.
"The new experimental database resulting from these tests will be used to further refine and validate a computer code that Sikorsky
and NASA developed in earlier testing," according to Thomas H. Bond, Project Manager at Lewis.
The code predicts the loss in helicopter rotor performance occurring when ice accumulates on the rotors during an icing encounter.
"We expect this code can be used to predict full-scale helicopter performance in icing after the code is further validated with full-scale flight test data.
Engineers also undertook a pioneering effort to define and develop the methodology for testing simulated icing shapes on rotors.
"We constructed molds of the ice buildup on the blades, and then produced castings or artificial ice shapes," continued Bond.
Engineers will now attach these shapes to the leading edges of the rotors of the scale model for testing in a conventional (dry air)
Bond goes on to explain, "We'll compare these dry air wind tunnel results for artificial ice shapes with the Icing Research Tunnel test
This is the first time artificial ice shapes have been seriously suggested as part of the icing certification process for rotary-wing
aircraft. Results of the testing will be made available to the U.S. helicopter industry for further recommendations.
"We hope that the code predictions and artificial ice shapes can ultimately be accepted as an alternative to some of the icing flight
testing now required by the Federal Aviation Administration to certify a helicopter for flight into forecasted icing," said Bond.
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