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Design of two Airfoils for a Canard Airplane

Martin Hepperle

For the airplane-project 'YAKA' (a development of the Ecole Nationale Supériore at Toulouse, France) two airfoils have been developed: Section MH 200 for application in the main wing and section MH 201 for the canard wing.

All results were obtained by using the Eppler-Code [1] for design and analysis of the airfoils. The design method of this code is based on conformal mapping while the analysis of various flap deflections is performed by a higher order panel method. Once the velocity-distribution is known, the drag-coefficients are calculated using an integral boundary layer analysis method. The lift- and momentum-coefficients from the potential theory are corrected for boundary layer effects (especially separation).

Section MH 200

The airfoil MH 200 has been designed to surpass the aerodynamic characteristics of the NACA 63₁-412 section while conserving maximum lift coefficient, momentum coefficient and at least retaining the thickness of 12 percent.

The results show some improvements:

the increased thickness of approximatly 13 percent allows a weight reduction of the main wing structure,
the laminar-bucket characteristics of the NACA 631-412 were avoided by incorporating a smooth change of transition location with variation of angle of attack,
the drag polars show improvements in the Reynoldsnumber range between 1·10⁶ and 8·10⁶ which should lead to better cruise performance of the entire aircraft. These effects were achieved without reducing the maximum lift coefficient or increasing the momentum coefficient,
positive flap deflections up to 10 degrees allow shifting the region of minimum drag to a lift coefficient c_l = 1.0 while performing better than the NACA 631-412 airfoil,
the same is true for negative flap deflections, moving the low drag region to c_l = -0.3 at a flap deflection of δ = -10°, thus resulting in lower drag in case of aileron and flap deflections.

Section MH 201

The airfoil MH 201 was intended to replace the NASA GA(W)-2 airfoil. The airfoil shows a smoother drag polar at the same or lower drag coefficients than the GA(W)-2. Flap deflections are more effective when compared to the NASA airfoil.

Bibliography

[1] R.Eppler, D.Somers: ‘A Computer Program for the Design and Analysis of Low-Speed Airfoils’, NASA TM-80210, 1980.

[2] R.J.Mc Ghee, W.D.Beasley: ‘Low Speed Aerodynamic Characteristics of a 13 Percent thick Airfoil Section designed for General Aviation Applications’, NASA TM X-72697, 1975.