The rear end of the wing is S, the apex of the wing is T, the front end of the wing is U, and the lowest point of the wing is V.

The lift generated by the wing in the above figure is considered to be equivalent to the lift generated by a wing with a length of 9.8 m with a square STUV as the cross section.

Therefore, the lift in each aspect is calculated.

1) Lift calculation on surface ST

Since the area is 1.07 x 9.8 = 10.5㎡ and the angle of attack of the surface ST is 8 °, the speed in the direction perpendicular to the surface ST (on the surface) at a flight speed of 150km / h is

150km / h x sin8 ° = 20.9km / h

The atmospheric pressure above 500m is 955hPa, the speed of sound is 1219km / h, and the force acting on the surface ST is

20.9km / h / 1219km / h x 955hPa / 1013hPa x 1kgf / ㎠ x 10000㎠ / ㎡ x 10.5㎡ = 1697kgf

In the vertical direction, 1697 x cos8 ° = 1680kgf,

Drag is 1697kgf x sin8 ° = 1697 x 0.139 = 236kgf.

2) Similarly for the surface TU

Area is 0.4 x 9.8 = 3.92㎡, angle of attack is minus 11.3 °

The straight speed is 150km / h x sin11.3 = 29.4km / h

The force acting on the surface TU is 890 kgf (downward), the vertical direction is -873 kgf (downward), and the drag is 174 kgf.

3) About surface UV

　 Area is 0.95 x 9.8 = 9.31㎡, angle attack is 5.3°

The straight speed is 150km / h x sin5.3° = 13.8km / h

The force acting on the surface UV is 994 kgf, the vertical direction is 990 kgf , and the drag is 91 kgf.

4) About surface VS

Area is 0.51 x 9.8 = 5.0㎡, angle of attack is minus 2 °

The straight speed is 5.25km / h

The force received by the surface VS is 203 kgf (downward), -203 kgf (downward) in the vertical direction, and the drag force is 7.0 kgf.

Therefore, in terms of overall lift,

1680-873 + 990-203 = 1594kgf

The total drag of the wings is 236 + 174 + 91 + 7 = 508kgf.

The drag force other than the wings has a projected area of about 0.2 m2.

150km / h / 1219km / h x 955hPa / 1013hPa x 1kgf / ㎠ x 10000㎠ / ㎡ x 0.2㎡ = 232kgf

Taking 35% of that, 81kgf

Therefore, the drag of the entire airplane is 508 + 81 = 589kgf.

The lift when this light aircraft is flying at 150km / h in the attitude shown in the conditions is 1594kgf.

The results of Case 2 are shown in the table below.

2020.10

Trial calculation of lift