8 Percent More Lift and 32 Percent Less Drag

[Larry Dighera]

Just when you thought aviation science had reached it limit:



http://www.aopa.org/members/files/pilot/2005/news0508.html
Dept. of R&D
A whale of a tale
To improve aircraft wing design, scientists have turned to one of the
most unlikely sources in nature: humpback whales.

Wind-tunnel tests using scale models of humpback pectoral flippers
have shown that the bumpy flipper is a more efficient design and has
better stall characteristics than anything currently in aviation. The
results were previously reported by researchers from West Chester
University, Duke University, and the U.S. Naval Academy in the journal
Physics of Fluids.

The researchers compared a smooth flipper, similar to a modern
airplane wing, with one that had bumps or what are called tubercles.
The bumpy flipper produced 8 percent more lift and 32 percent less
drag, and stalled at a 40 percent steeper angle. The researchers said
that as a whale moves through water, the tubercles cause swirling
vortices by disrupting the line of pressure against the leading edge
of the flippers. The water is redirected into the scalloped valleys
between the tubercles, keeping the flow attached to the upper surface
of the flipper.

The findings could be applied not only to airplane wings, but also to
the tips of helicopter rotors, airplane propellers, and ship rudders.

[Mike Rapoport]

Just proves once more why you should leave the bugs on the leading edges.

Mike
MU-2


"Larry Dighera" > wrote in message
...
>
> Just when you thought aviation science had reached it limit:
>
>
>
> http://www.aopa.org/members/files/pilot/2005/news0508.html
> Dept. of R&D
> A whale of a tale
> To improve aircraft wing design, scientists have turned to one of the
> most unlikely sources in nature: humpback whales.
>
> Wind-tunnel tests using scale models of humpback pectoral flippers
> have shown that the bumpy flipper is a more efficient design and has
> better stall characteristics than anything currently in aviation. The
> results were previously reported by researchers from West Chester
> University, Duke University, and the U.S. Naval Academy in the journal
> Physics of Fluids.
>
> The researchers compared a smooth flipper, similar to a modern
> airplane wing, with one that had bumps or what are called tubercles.
> The bumpy flipper produced 8 percent more lift and 32 percent less
> drag, and stalled at a 40 percent steeper angle. The researchers said
> that as a whale moves through water, the tubercles cause swirling
> vortices by disrupting the line of pressure against the leading edge
> of the flippers. The water is redirected into the scalloped valleys
> between the tubercles, keeping the flow attached to the upper surface
> of the flipper.
>
> The findings could be applied not only to airplane wings, but also to
> the tips of helicopter rotors, airplane propellers, and ship rudders.
>

[Seth Masia]

See Scientific American, about a year ago:
http://www.sciamdigital.com/browse.cfm?sequencenameCHAR=item2&methodnameCHAR=resource_getitembrowse&interfacenameCHAR=browse.cfm&ISSUEID_CHAR=A4AD4ADB-2B35-221B-699D1485A73879AA&ARTICLEID_CHAR=A4B65445-2B35-221B-655AE8D9744434BC&sc=I100322


"Mike Rapoport" > wrote in message
ink.net...
> Just proves once more why you should leave the bugs on the leading edges.
>
> Mike
> MU-2
>
>
> "Larry Dighera" > wrote in message
> ...
>>
>> Just when you thought aviation science had reached it limit:
>>
>>
>>
>> http://www.aopa.org/members/files/pilot/2005/news0508.html
>> Dept. of R&D
>> A whale of a tale
>> To improve aircraft wing design, scientists have turned to one of the
>> most unlikely sources in nature: humpback whales.
>>
>> Wind-tunnel tests using scale models of humpback pectoral flippers
>> have shown that the bumpy flipper is a more efficient design and has
>> better stall characteristics than anything currently in aviation. The
>> results were previously reported by researchers from West Chester
>> University, Duke University, and the U.S. Naval Academy in the journal
>> Physics of Fluids.
>>
>> The researchers compared a smooth flipper, similar to a modern
>> airplane wing, with one that had bumps or what are called tubercles.
>> The bumpy flipper produced 8 percent more lift and 32 percent less
>> drag, and stalled at a 40 percent steeper angle. The researchers said
>> that as a whale moves through water, the tubercles cause swirling
>> vortices by disrupting the line of pressure against the leading edge
>> of the flippers. The water is redirected into the scalloped valleys
>> between the tubercles, keeping the flow attached to the upper surface
>> of the flipper.
>>
>> The findings could be applied not only to airplane wings, but also to
>> the tips of helicopter rotors, airplane propellers, and ship rudders.
>>
>
>

[Jose]

> The bumpy flipper produced 8 percent more lift and 32 percent less
> drag, and stalled at a 40 percent steeper angle. The researchers said
> that as a whale moves through water, the tubercles cause swirling
> vortices

Of course the physics is different, but it reminds me of an ad in
Scientific American some thirty years ago touting the benefits of the
new "rough" coating on electric cables, which allowed lower friction
when being pulled through a conduit.

Jose
--
Quantum Mechanics is like this: God =does= play dice with the universe,
except there's no God, and there's no dice. And maybe there's no universe.
for Email, make the obvious change in the address.

[Larry Dighera]

On Fri, 19 Aug 2005 09:58:32 -0700, "Seth Masia" >
wrote in >::

>
>See Scientific American, about a year ago:
>http://www.sciamdigital.com/browse.cfm?sequencenameCHAR=item2&methodnameCHAR=resource_getitembrowse&interfacenameCHAR=browse.cfm&ISSUEID_CHAR=A4AD4ADB-2B35-221B-699D1485A73879AA&ARTICLEID_CHAR=A4B65445-2B35-221B-655AE8D9744434BC&sc=I100322

Many thanks for the link.

Here are some more:
http://biomechanics.bio.uci.edu/_html/nh_biomech/whaleturn/whaleturn.htm
http://www.boatdesign.net/forums/showpost.php?p=25933&postcount=29
http://www.findarticles.com/p/articles/mi_m1134/is_5_113/ai_n6062533
http://www.cdnn.info/article/ocean_envy/ocean_envy.html
http://www.rcgroups.com/forums/showthread.php?t=259792&pp=15
http://www.sciencenews.org/articles/20040904/bob9.asp
http://academic.amc.edu.au/~tclarke/TobiasClarkeThesis.PDF

[Larry Dighera]

On Fri, 19 Aug 2005 18:03:36 GMT, Jose >
wrote in >::

>> The bumpy flipper produced 8 percent more lift and 32 percent less
>> drag, and stalled at a 40 percent steeper angle. The researchers said
>> that as a whale moves through water, the tubercles cause swirling
>> vortices
>
>Of course the physics is different,

Yes. Completely.

>but it reminds me of an ad in
>Scientific American some thirty years ago touting the benefits of the
>new "rough" coating on electric cables, which allowed lower friction
>when being pulled through a conduit.

As a union electrician for 40+ years, this is the first mention I have
heard of that. Interesting.

[Seth Masia]

So the leading-edge bumps play the same role as vortex generators, but
because they work in a more viscous medium (about 100x more viscous than
air) they're a lot more effective. It will be interesting to see if anyone
has success with an RC airplane with lumpy wings; or if sailboats will
adopt lumpy rudders.


"Larry Dighera" > wrote in message
...
> On Fri, 19 Aug 2005 18:03:36 GMT, Jose >
> wrote in >::
>
>>> The bumpy flipper produced 8 percent more lift and 32 percent less
>>> drag, and stalled at a 40 percent steeper angle. The researchers said
>>> that as a whale moves through water, the tubercles cause swirling
>>> vortices
>>
>>Of course the physics is different,
>
> Yes. Completely.
>
>>but it reminds me of an ad in
>>Scientific American some thirty years ago touting the benefits of the
>>new "rough" coating on electric cables, which allowed lower friction
>>when being pulled through a conduit.
>
> As a union electrician for 40+ years, this is the first mention I have
> heard of that. Interesting.

[Denny]

Actually, we began to fly with bumpy wings, or tubercles, from the
Wright Brorthers onwards... Look at any ragwing and you will see the
tubercles at regular intervals......

And even the whale researchers are behn the power curve... Some guy has
a patent on tape you run along the wing at the approx. 20% of chord,
which has pits on it, like a golf ball... Makes great claims to
improved stalling speeds, etc... And of course, there are the vortex
generator folks...
What goes around comes around...

denny

[Hilton]

The guy doing the research on a Whale is called Fish? I bet his startup
gets swallowed up by a larger company. ;)

Hilton


"Seth Masia" > wrote in message
...
> See Scientific American, about a year ago:
>
http://www.sciamdigital.com/browse.cfm?sequencenameCHAR=item2&methodnameCHAR=resource_getitembrowse&interfacenameCHAR=browse.cfm&ISSUEID_CHAR=A4AD4ADB-2B35-221B-699D1485A73879AA&ARTICLEID_CHAR=A4B65445-2B35-221B-655AE8D9744434BC&sc=I100322
>
>
> "Mike Rapoport" > wrote in message
> ink.net...
> > Just proves once more why you should leave the bugs on the leading
edges.
> >
> > Mike
> > MU-2
> >
> >
> > "Larry Dighera" > wrote in message
> > ...
> >>
> >> Just when you thought aviation science had reached it limit:
> >>
> >>
> >>
> >> http://www.aopa.org/members/files/pilot/2005/news0508.html
> >> Dept. of R&D
> >> A whale of a tale
> >> To improve aircraft wing design, scientists have turned to one of the
> >> most unlikely sources in nature: humpback whales.
> >>
> >> Wind-tunnel tests using scale models of humpback pectoral flippers
> >> have shown that the bumpy flipper is a more efficient design and has
> >> better stall characteristics than anything currently in aviation. The
> >> results were previously reported by researchers from West Chester
> >> University, Duke University, and the U.S. Naval Academy in the journal
> >> Physics of Fluids.
> >>
> >> The researchers compared a smooth flipper, similar to a modern
> >> airplane wing, with one that had bumps or what are called tubercles.
> >> The bumpy flipper produced 8 percent more lift and 32 percent less
> >> drag, and stalled at a 40 percent steeper angle. The researchers said
> >> that as a whale moves through water, the tubercles cause swirling
> >> vortices by disrupting the line of pressure against the leading edge
> >> of the flippers. The water is redirected into the scalloped valleys
> >> between the tubercles, keeping the flow attached to the upper surface
> >> of the flipper.
> >>
> >> The findings could be applied not only to airplane wings, but also to
> >> the tips of helicopter rotors, airplane propellers, and ship rudders.
> >>
> >
> >
>
>

[Brian]

It's called Turbulator Tape or another style is called zig zag tape. It
has been used on glider wings for many years.

Brian
CFIIG/ASEL