Re: [dinosaur] Archaeopteryx had active flapping flight ability based on wing bone geometry (free pdf)

[Mike Habib <biologyinmotion@gmail.com>]

Running launch is an adaptation to water takeoff; it is a specialist form of 
takeoff and is not typical of most birds. 

In most cases, terrestrial launch is initiated via leaping (ie it is hind limb 
driven). The wings engage in a downstroke *after* toe off, exactly as Tim 
noted. In fact, leaping launch powered by the walking limbs is typical for both 
powered and unpowered flyers (see work by Earls, Tobalske, Nachtigall, etc). 
This is why launch is can be looked at as a two-phase process: a walking limb 
driven phase I (launch proper) and a wing driven phase II (climb out).

The role of the wings in water launch is not well understood. Water birds can 
run on the surface without using the wings, so the build up of speed across the 
surface seems not to be wing dependent. It is likely that the wings are used 
either for stability or simply to build vorticity prior to launch (ie to 
counter the Wagner Effect), since running launch accelerations are lower than 
leaping launch accelerations.

Cheers,

âMike Habib

Sent from my Cybernetic Symbiote

> On Mar 14, 2018, at 3:39 AM, Ruben Safir <ruben@mrbrklyn.com> wrote:
> 
>> On 03/13/2018 11:29 PM, Tim Williams wrote:
>> Vertical take-offs are initiated by the hindlimbs in extant
>> birds (Earls 2000 JEB 203: 725-739), and it's likely that
>> _Archaeopteryx_ was capable of the same (leaping into the air, with no
>> need for a running take-off; Dececchi et al. 2016 DOI
>> 10.7717/peerj.2159). The wings are deployed for the climb-out phase of
>> the launch, and a modern avian flight stroke is not essential for this
>> - just large wings capable of thrust generation.
> 
> Without the lift from the wing stroke the bird just lands on its face
> and the separation of these two aspects of launch that you make here is
> illogical.  Furthermore, despite what Earls says, I recommend you walk
> out to Sheepshead Bay in Brooklyn and watch how Swans and Ducks actually
> get into the air.  Swans are not leaping into the air and then taking
> off on winged power.  They 100% depend on building air speed with a
> combination of flight stroke and running on the water.  Without a
> sternum to anchor chest muscles, that is going to be more true, not
> less.  Flight stroke IS 100% essential.  Maybe there is someones next
> research paper.
> 
>