Four-Winged Flapping Flyer in Forward Flight - Selected Topics of Computational and Experimental Fluid Mechanics - page 145

Fig. 1 To p sketch of the experimental setup. Bottom photos of the flapping flyer with forewing-
hindwing phase lags 0 ( left )and

ˀ

( right ). Each wing has a semi-circular shape so that c =

30mm

and L = 60mm. The distance between the wings d =

1mm, so that the trailing edge of the forewing
and the leading edge of the hindwing almost touch when the wings are aligned without bending;
the stroke amplitude max

37 ⓦ . Wings are made of 0.05mm thick Mylar (ʸ fw ) = max (ʸ hw ) = ʸ 0 =

10 − 5 Nm The leading edge is thicker (1mm) and made of
fiberglass so that it can be considered rigid and the deformation exclusively chord-wise

that gives a flexural rigidity B =

. ×

3 3

general be analysed simultaneously with the forewing-hindwing phase lag (Maybury
and Lehmann 2004 ; Rival et al. 2011 ). The motion of the wings is described using
the angles of the forewing and hindwing leading edges to the xz -plane, ʸ fw and ʸ hw ,

respectively (see Fig. 1 ), as

ʸ fw = ʸ 0 sin ( 2 ˀ ft ) and ʸ hw = ʸ 0 sin ( 2 ˀ ft − ˕), (1)

˕ ˀ

where f is the flapping frequency and the phase lag is varied between 0 and 2 .

For 0 <˕<ˀ the forewing is leading, whereas for ˀ<˕< 2 ˀ it is the hindwing

that leads. The Reynolds number Re = Uc /ʽ based on the cruising speed and the

chord length was in the range of 1,000-4,000.
The measured quantities are the cruising flight speed U and the consumed power
P i . In the study of the two winged flyer of Thiria and Godoy-Diana ( 2010 ) and
Ramananarivo et al. ( 2011 ) an additional independent setup was used to measure the
thrust force F by holding the flyer in a stationary position. The product of the force