> Ian Woollard wrote:
>>
>> Rutan's Voyager managed 10:1, so probably not that much different
>> Isp/lift wise. We're possibly not talking orders of magnitude 
>> better.
>> I did wonder whether the fact that birds have a much smaller 
>> ballistic
>> coefficient made a big difference, but then again birds fly in that
>> v-formation which gives some of the effects of a much bigger 
>> vehicle,
>> and probably helps make up for it.
>>
>
>
> Albatross
> 25Watts/kg  'apparent ISP' ~1.28e6s L/D of ~20 'thrust ISP' ~64000s
>
> Voyager
> 140watts/kg  'apparent ISP' ~0.35e6s L/D of ~27 'thrust ISP' ~13000s
>
> Not based on tremendously reliable data so take it with a pinch of 
> salt...

Looks like they have a few extra tricks that even Voyager couldn't 
manage :-)

|| ...  the birds go on a binge, a feeding frenzy, before their long 
haul flights until up to 55 per cent of their weight is fat. They then 
reduce the size of their gut, kidney and liver by up to 25 per cent to 
compensate for the added weight. Obese with fuel, freed from the 
baggage of a heavy guts, the godwit are ready for the air. The 
scientists think that the birds reshuffle proteins in their bodies 
before they set out and that this allows them to reduce the size of 
their food-processing organs.

More related interesting stuff here

        http://www.nzbirds.com/birds/kuaka.html

and other NZ birds here

        http://www.nzbirds.com/birds



        Russell
]

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