Tubercles lower stalling airspeed?

Jokes aside, this is serious research:

'...The potential was enough for the Ontario Centres
of Excellence and the Ontario Power Authority to contribute
about $70,000 in early-stage research funding, and
to encourage collaboration with the wind-engineering
group at the University of Western Ontario. Independent
third-party verification of the new blade's performance
will be a crucial step toward commercial production.

snip...

It turns out the key to a humpback's agility lies in
its long flippers, which feature a unique row of bumps
or 'tubercles' along their leading edge that give the
wing-like appendages a serrated look. Researchers such
as Frank Fish, a professor of biology at West Chester
University in Pennsylvania, have found that the tubercles
dramatically increase the whale's aerodynamic efficiency.

In one particular study conducted inside a controlled
wind tunnel, Fish and research colleagues at Duke University
and the U.S. Naval Academy saw 32 per cent lower drag
and an 8 per cent improvement in lift from a flipper
with tubercles compared to a smooth flipper found on
other whales.

They also discovered that the angle of attack of the
bump-lined flipper could be 40 per cent steeper than
a smooth flipper before reaching stall – that is, before
seeing a dramatic loss in lift and increase in drag.
In an airplane scenario, that's typically when you
lose control and crash.

'That stall typically occurs on most wings at 11 or
12 degrees at the angle of attack,' says Fish, adding
that with the humpback design 'stall occurred much
later, at about 17 or 18 degrees of attack. So the
stall is being delayed.'

The implications are potentially enormous. Delayed
stall on airplane wings can improve safety and make
planes much more manoeuvrable and fuel-efficient. The
same benefits can also be found on ship and submarine
rudders, which explains the U.S. Navy's quiet involvement.'

Earlier, Angus Mac Lir wrote:

Jokes aside, this is serious research...

Definitely. Ornithopter developers are going to be all over it.

Bob K.

On May 15, 1:08 pm, Angus Mac Lir
wrote:
Jokes aside, this is serious research:

'...The potential was enough for the Ontario Centres
of Excellence and the Ontario Power Authority to contribute
about $70,000 in early-stage research funding, and
to encourage collaboration with the wind-engineering
group at the University of Western Ontario.

What fluid did they use for the tests? Water and air have somewhat
different Reynolds numbers. If the whale wings really worked that
well in normal sea level O2N2 mix I would be kind of surprised. I can
believe they might have some advantage at whale speeds in H20.

the word is hydrodynamic
not aerodynamic, same principle though


bagger

I uncovered a video of the testing.

http://tinyurl.com/2umfup

(note that the bowl of petunias still achieved a slightly better
minimum sink rate)

I tracked down a video of the actual testing:

http://tinyurl.com/37otk9

As previously suggested both the minimum sink rate (that term could
apply equally to aerodynamics and hydrodynamics I suppose) and L/D do
indeed seem to come out about very similar to the bowl of petunias (if
you watch closely).

wrote:
I uncovered a video of the testing.

http://tinyurl.com/2umfup

(note that the bowl of petunias still achieved a slightly better
minimum sink rate)


I don't think that was a hump back. Isn't that what was under
discussion?? :-)
...lew...