AirTabs shown to work by respected EM member

[wmjinman]

Originally Posted by freebeard

He concludes that water moving at 0.1m/s is equivalent to air moving at 2m/s.

Yeah, I think I understand; instead of trying to get insight from the skin of a shark, Or maybe the shape of a fast bird, etc, how much more effective to use the "aerodynamics" of a super-high speed creature like a lobster.

[Xist]

Originally Posted by wmjinman

Yeah, I think I understand; instead of trying to get insight from the skin of a shark, Or maybe the shape of a fast bird, etc, how much more effective to use the "aerodynamics" of a super-high speed creature like a lobster.

I take my nephew to swim lessons every week because, as much as I love him, I love him more on the other side of a glass wall where I cannot hear him.

Each class has a mascott: Sharks, barracudas, dolphins, etc.

Level four is starfish.

How fast do starfish swim?

I guess that is better than barnacle, though.

[ChazInMT]

Somebody say Shark Skin???? Here's one of the coolest pics EVAH of sharkskin imaged with a scanning electron microscope. Eye of Science credit.




Good luck figuring that out! I never cease to be astounded by the complex shapes seen here, I think there is a lifetimes work in this picture alone trying to make sense of it.

[freebeard]

wmjinman -- It's been done:

Just not well.

ChazInMT -- Did you ever *really* look at shark skin? I'd like to see one of those plates in isolation; they must interlock.

Look at the boxfish skin at 1:30 in the following video. It's a triangulated mesh.

All -- Did I mention testing in a water flume? Why, yes I did.

Bionic Car | Mercedes-Benz

At 0:23 to 0:44 they show Mercedes Benz' well-paid engineers using a 1/3 scale clay model underwater—with SCUBA. The pulsed walls of air bubbles is something I've wanted to see.

Now I want to see pulsed bubbles of florescent green smoke.

aerohead -- Consider this a response to you post here.

Did you look at Suzuka's work? Desktop tuft testing? If you watch Part 1 you might well be skeptical, but in Part 4 he analyzes his results and compares with his full-scale moving floor tunnel work. His resumé is in Part 5

[aerohead]

*The flume would be okay for evaluating 2-D flow of AirTabs on any section.
*You wouldn't be able to test for 3-D flow though.That would require a water tunnel and a model of no more than 5% blockage ratio in relation to the test section's cross-sectional area.
*Water tunnels are problematic,as it's hard to penetrate the ground plane with the 3-axis balance.
*They typically require that the model be mounted to an overhead sting (as OPEL does with it's moving ground floor tunnel) and all force measurements are taken from 'above.'
*Texas Tech constructed an underwater tow tank in which the model road the floor of the tank,connected to a sting,which was attached to an overhead gantry crane which road on rails just like the US NAVY's David Taylor Model Basin in Maryland.
*This would make 3-D flow visualization and drag measurement possible.

[aerohead]

He's covered the Reynolds number 'verisimilitude' which is so critical for scale-model testing.
A leaf-blower will produce air speeds good enough for 1/24th-scale testing,so anyone with the chops to cover all the bases should be able to pull off the repeatability as Suzuka.
He has a nice setup! Way fun!
Thanks for sharing that.

[freebeard]

No problem. He impresses me.

Did you see the Mercedes Benz engineers in their SCUBA gear? I notice they way exceed 5% blockage.

I like the Texas Tech setup. Have you seen

Sauber wind tunnel at Hinwil (full HD

? Overhead sting so they can load the suspension.

[aerohead]

Originally Posted by freebeard

No problem. He impresses me.

Did you see the Mercedes Benz engineers in their SCUBA gear? I notice they way exceed 5% blockage.

I like the Texas Tech setup. Have you seen

? Overhead sting so they can load the suspension.

*I've only a still photo of the underwater model testing.'don't know if divers were actually down there during measurements.It made for dramatic photos though!
* wheels on the tank floor 'ground',necessitated the overhead measurements so they were kinda forced into that configuration.They should have been able to measure loads in all three axis.
*I've not seen the Sauber setup (I don't get to play very much lately),I really like it! With $millions on the table and bragging rights for the F-1 winner,they've got to do all they can within the rulebook parameters to have a shot at the Bouguet and champagne.

[freebeard]

(I don't get to play very much lately)

All I have is time and a DSL connection.

The Secret Life of Vortices: Evolution and Destruction of Vortical Flows

[aerohead]

I ran across a VG-related article from KITPLANES,Vol. 15,No.4,April,1998,Pgs 60-67, by Terrence O'Neill.
O'Neill had been in the market for a safe aircraft for he and his wife.
He narrowed the field to a Viking Dragonfly,tandem-wing,with low canard,high rear-wing.He added VGs to the canard after re-reading a 1993 Barnaby Wainfan article in KITPLANES on tandem-wing aircraft.
Piper Advanced Technology-1 designer George Meade was killed in this aircraft after experiencing what NASA termed a 'trim' (would remain stalled) event if C.G. was too far aft and power on.Prop blast held the canard at the stalled angle of attack.It was non-recoverable.
O'Neill had installed a set of Bacon-Saver angle of attack (AOA) indicators on his Dragonfly.On his first flight he experienced no funny business up to 12-degrees AOA,then at 13-degrees AOA the canard went bobbing into partial stall.
I've no data on the Dragonfly canard but I looked at a Clark Y I have data on.
At 0-degrees AOA,its upper contour goes to 11-degrees down-slope.
At 12-degrees 'clean' flying,the upper surface is at 23-degrees,Rolf Buchheim's recommended slope maximum for automobiles,and 1-degree steeper than what W.A.Mair has recommended.
As it happens,one of my fluid mechanics texts has a 3-photo montage of a Clark Y 'flying' in the wind tunnel.
*@ 12-degrees AOA there is perfect flow attachment on top over the 23-degree max. slope.
*@ 17-degrees AOA,88% of the wing is in separated flow with no re-attachment.
*@ 19-degrees AOA,the wing is stalled over the entire upper contour.
All this in spite of the presence of VGs.
On the You-Tube video from the old NACA film you can watch the stall progress as a function of AOA.
PS I found the image in the phil knox photo albums under Book Illustrations,page-1,line-5,far right image.(needs to be rotated)