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Assuming a Goose weights around 5 kilos and taking into account the isometric proportion in birds increasing their weight lifting abilities, when we relate this to the Hawk (capable of lifting 1.5 kilos) weighing 900 grammes, and estimating twice the bird weight lift capacity, we could suppose 10 kilos per goose. That would be an answer of about 120.
Maximum Lift Production During Takeoff in Flying Animals JAMES H. MARDEN
Department of Zoology, University of Vermont, Burlington, VT 05405, USA
Maximum lift production during takeoff in still air was determined for a wide variety of insects and a small sample of birds and bats, and was compared with variation in morphology, taxonomy and wingbeat type. Maximum lift per unit flight muscle mass was remarkably similar between taxonomic groups (54-63 N kg-1), except for animals using clap-and-fling wingbeats, where muscle mass-specific lift increased by about 25 % (72-86 N kg-1). Muscle mass-specific lift was independent of body mass, wing loading, disk loading and aspect ratio. Birds and bats yielded results indistinguishable from insects using conventional wingbeats. Interspecific differences in short-duration powered flight and takeoff ability are shown to be caused primarily by differences in flight muscle ratio, which ranges from 0.115 to 0.560 among species studied to date. These results contradict theoretical predictions that maximum mass-specific power output and lift production should decrease with increasing body mass and wing disk loading.
Maximum induced power output can be estimated for animals whose maximum lift force and wing length are known by using the actuator-disk equation from helicopter aerodynamic theory (Hoff, 1919; Weis-Fogh, 1972; Alexander, 1983):
where P, is induced power (W),
L is lift (N), p is air density (kg m~3), and r is wing semi-span (span/2; m). The units of the right-hand side of the equation convert to Watts (i.e. kgm2s~3). Using this equation with the measured maximum lift force of 14.46N for Harris' hawks, and assuming a wing length 0.50 m (Robbins et al. 1966), yields an estimate of maximum induced power output of 39.7 W, which is very close to Pennycuick et a/.'s empirically derived 40-46 W. This result demonstrates that it is possible to predict maximum P, from measurements of maximum lift and wing length. Furthermore, applying the helicopter equation to Marden's (1987) data for lift and wing semi-span from a wide variety of birds, bats and insects shows that the scaling of estimated P; with body mass also predicts the measured maximum P.
Marden (1987) showed that maximum load-lifting among a diverse sample of birds, bats and insects was an isometric function of total flight muscle mass, with little interspecific variation (r
2=0.99). This result was not predicted by previous data or theory, and to date had not been confirmed with independent measurements from other studies. Because the largest animal used in Marden's study was a pigeon (0.267 kg), results from Harris' hawks (0.920 kg) also permit a further test of the isometry of maximum lift production.
Estimates of maximum load-lifting and of flight muscle mass from Harris' hawks are necessary to compare their performance with that of other flying animals.
Pennycuick et al. (1989) determined that Harris' hawks were able to gain altitude while carrying 1.4 kg, but not while carrying 1.55 kg.
"It's not a question of where he grips it at. It's a simple question of weight ratio."
I don't know if anyone got this but Monty Python and the quest for the holy grail is on my top movies of all time.
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