Instantaneous acceleration of the COM during wing-assisted incline running and during ascending flight
| . | Acceleration vector . | . | . | . | |||
|---|---|---|---|---|---|---|---|
| . | During WAIR . | . | During flight . | . | |||
| Wing position . | Magnitude (g) . | Orientation (degrees) . | Magnitude (g) . | Orientation (degrees) . | |||
| Start of downstroke (SDS) | 2.8±0.2 | 9±15 | 3.0±0.2 | 327±8 | |||
| Middle of downstroke (MDS) | 2.0±0.2 | 15±17 | 2.0±0.3 | 61±22 | |||
| Second third of downstroke (0.66DS) | 1.7±0.2 | 121±15 | 3.8±0.2 | 86±8 | |||
| End of downstroke (EDS) | 2.2±0.2 | 111±13 | 2.9±0.1 | 72±7 | |||
| First third of upstroke (0.33US) | 0.8±0.2 | 163±17 | 1.1±0.3 | 142±36 | |||
| Middle of upstroke (MUS) | 0.7±0.3 | 187±24 | 0.2±0.3 | 263±45 | |||
| . | Acceleration vector . | . | . | . | |||
|---|---|---|---|---|---|---|---|
| . | During WAIR . | . | During flight . | . | |||
| Wing position . | Magnitude (g) . | Orientation (degrees) . | Magnitude (g) . | Orientation (degrees) . | |||
| Start of downstroke (SDS) | 2.8±0.2 | 9±15 | 3.0±0.2 | 327±8 | |||
| Middle of downstroke (MDS) | 2.0±0.2 | 15±17 | 2.0±0.3 | 61±22 | |||
| Second third of downstroke (0.66DS) | 1.7±0.2 | 121±15 | 3.8±0.2 | 86±8 | |||
| End of downstroke (EDS) | 2.2±0.2 | 111±13 | 2.9±0.1 | 72±7 | |||
| First third of upstroke (0.33US) | 0.8±0.2 | 163±17 | 1.1±0.3 | 142±36 | |||
| Middle of upstroke (MUS) | 0.7±0.3 | 187±24 | 0.2±0.3 | 263±45 | |||
COM, center of mass; WAIR, wing-assisted incline running.
Values are means ± S.E.M. (N=121 wingbeats, from 3 birds,during WAIR; N=57 wingbeats, from 4 birds, during ascending flight). These same values are presented graphically in Fig. 3.
During the second half of downstroke the orientation of the acceleration vector is directed towards the substrate during running, and in line with the direction of travel during flight (wing positions 0.66DS through EDS).