Phase II Final Report - NASA's Institute for Advanced Concepts

Chapter 3.0 Vehicle Design
3.3 Wing Aerodynamics
This will further increase the number of cases required to be evaluated. The best option would
be to perform CFD analyses for all these cases, and validating by experimental runs in the wind
tunnel, to account for the unsteady effects of flapping wing flight. The experimental runs can be
compensated for the Earth's environment and then based on Reynolds Number, the results could
be extrapolated for the Mars Environment.
Empirical results can be generated on a newly constructed flapping wing simulator in the GTRI
wind tunnels (See Figure 3-133.). This hardware simulator, developed under a DARPA-funded
project, is capable of operating with a full scale blown winglet of the exact planform used by the
Mars Entomopter and at speeds comparable to those used in the CFD simulations. These wind
tunnel tests are beyond the scope of work originally proposed under this NIAC Phase II effort,
but will be conducted as follow-on work to advance and refine the CFD and analytical models
developed here.
Figure 3-133: GTRI Kinematically-correct Full-scale Wind Tunnel Wing Flapping
Simulator
3.3.4 Active Flow Control (“Blowing” of the Wings)
Even though positive net lift is obtained from both the CFD and analytical solutions, the force is
not sufficient for flight in Mars’ lower atmosphere. Hence, active flow control technology will
be used to augment the lift, and thrust along with reducing the drag of the Entomopter. The
reciprocating chemical muscle-based propulsion of Entomopter provides exhaust that can be
used as a supply of gas for circulation control. Blowing of the wing in a proper way is critical
not only to the stability and control of the Entomopter, but in the Mars application, its ability to
fly. Experiments on Earth in the wind tunnel have shown that blowing can achieve phenomenal
results, with increases in lift by a factor of ten [83, 84]. Under the NIAC Phase II study, incorporation
of the affects of blowing within the analytical formulation were not possible, though this
has been identified as a follow-on effort. Similarly, the optimal computational description of the
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