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new wingtip design



 
 
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  #11  
Old February 28th 15, 12:48 PM posted to rec.aviation.soaring
Martin Gregorie[_5_]
external usenet poster
 
Posts: 1,234
Default new wingtip design

On Fri, 27 Feb 2015 22:02:08 -0800, mmartin46 wrote:

I've been flying airplanes professionally for close to forty years and
sailplanes for fun. I spend a lot of time looking at the wing trying to
understand how it works. In the end, I conclude it's all magic. I
kinda like that.


I've never forgotten one cloudy day with a low overcast. I was in a car,
driving away from Heathrow toward Chobham Common, which put us directly
under the approach to Heathrow, when a 747 dropped out of the overcast on
finals. For a few seconds it was heading for us, grabbing the bottom of
the cloud and flinging it at the ground: it was like watching a waterfall
beneath its wing.

That sight made me realise two things: that a 747 really does weigh a
couple hundred tons and that the reaction from deflecting that huge mass
of air downward has more than a little to do with keeping it in the air.


--
[email protected] | Martin Gregorie
gregorie. | Essex, UK
org |
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  #12  
Old February 28th 15, 04:36 PM posted to rec.aviation.soaring
John Firth[_4_]
external usenet poster
 
Posts: 57
Default new wingtip design

At 04:59 28 February 2015, Paul Villinski wrote:
As a non-scientist/engineer, it baffles me that we are able to build
amazin=
gly sophisticated airplanes, yet, as the lecturer demonstrates, there is

a
=
huge amount of confusion over how to explain why a wing produces lift,

and
=
many of our common assumptions are simply wrong, i.e., the reason(s) for
ac=
celerated airflow over the top surface (which intuitively has never made
se=
nse to me). Engineers designing airplanes are themselves still arguing
over=
whether it's more about Bernoulli or the downward-turning force or

Coanda
=
effect. Yet, I'm still able to get from one coast to another at 35,000
feet=
traveling at 600 mph, while sipping coffee and watching a movie.

A reasonable parallel is the dual nature of light, which can be treated as
both wave and particle. Both models
explain the result.

John Firth

  #13  
Old February 28th 15, 06:16 PM posted to rec.aviation.soaring
Kevin Neave[_2_]
external usenet poster
 
Posts: 64
Default new wingtip design

Glider wings work on faith.

It's easy to have faith at 4-5000ft so the wings work well & soaring is
easy.

'Tis more difficult to have faith at 1000ft so wings work less well &
gliding is more tricky.

Much below 1000ft I lose all faith & land shortly after.

This assumes UK feet where 5000 is "High" not American / Australian / South
African feet where 5000 is "Low".

KN

At 15:36 28 February 2015, John Firth wrote:
At 04:59 28 February 2015, Paul Villinski wrote:
As a non-scientist/engineer, it baffles me that we are able to build
amazin=
gly sophisticated airplanes, yet, as the lecturer demonstrates, there i

a
=
huge amount of confusion over how to explain why a wing produces lift

and
=
many of our common assumptions are simply wrong, i.e., the reason(s) for
ac=
celerated airflow over the top surface (which intuitively has never made
se=
nse to me). Engineers designing airplanes are themselves still arguing
over=
whether it's more about Bernoulli or the downward-turning force o

Coanda
=
effect. Yet, I'm still able to get from one coast to another at 35,000
feet=
traveling at 600 mph, while sipping coffee and watching a movie.

A reasonable parallel is the dual nature of light, which can be treated a
both wave and particle. Both models
explain the result.

John Firth



  #14  
Old February 28th 15, 06:19 PM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 3,345
Default new wingtip design

I must admit that I didn't read the article thoroughly, but it seemed to
me by looking at the picture that the thing would enhance wingtip
vortices (the Windows spell checker did not like that word, BTW).
Anyway, I thought the idea was to reduce vortices since they're wasted
energy that could be used by the aircraft.

Aero engineers, please chime in.

On 2/28/2015 2:54 AM, Skypilot wrote:
The biggest problem is trying to prove up the % saved. Then you have to
convince the bean counters.


ND;897867 Wrote:
interesting article about a potential winglet replacement for jets.

I personally think that winglets have more sex appeal though, especially
maughmer's.

http://tinyurl.com/37q5aeb





--
Dan Marotta

  #15  
Old March 1st 15, 12:54 AM posted to rec.aviation.soaring
BobW
external usenet poster
 
Posts: 418
Default new wingtip design

On 2/28/2015 10:19 AM, Dan Marotta wrote:
I must admit that I didn't read the article thoroughly, but it seemed to me by
looking at the picture that the thing would enhance wingtip vortices (the
Windows spell checker did not like that word, BTW). Anyway, I thought the
idea was to reduce vortices since they're wasted energy that could be used by
the aircraft.

Aero engineers, please chime in.


I had the same off-the-cuff gut reaction when I first looked at it, too. Upon
further cogitation, I'm still uncertain eggzackly what-n-how the designer was
seeking to achieve what I think he was seeking to achieve. I also noticed the
article said he was an aeronautics teacher, so this may be a case of: Those
who can't do, teach!

In any event, I'm not investing my retirement in any company trying to make
and sell these babies...

Bob W.

  #16  
Old March 1st 15, 01:09 AM posted to rec.aviation.soaring
Bob Whelan[_3_]
external usenet poster
 
Posts: 389
Default new wingtip design

On 2/28/2015 4:48 AM, Martin Gregorie wrote:
On Fri, 27 Feb 2015 22:02:08 -0800, mmartin46 wrote:

I've been flying airplanes professionally for close to forty years and
sailplanes for fun. I spend a lot of time looking at the wing trying to
understand how it works. In the end, I conclude it's all magic. I
kinda like that.


I've never forgotten one cloudy day with a low overcast. I was in a car,
driving away from Heathrow toward Chobham Common, which put us directly
under the approach to Heathrow, when a 747 dropped out of the overcast on
finals. For a few seconds it was heading for us, grabbing the bottom of
the cloud and flinging it at the ground: it was like watching a waterfall
beneath its wing.

That sight made me realise two things: that a 747 really does weigh a
couple hundred tons and that the reaction from deflecting that huge mass
of air downward has more than a little to do with keeping it in the air.


Agreed...and for the sake of pub discussions, I think it's entirely
sufficient. Where the explanation quickly becomes complex is when we attempt
to mathematically analyze lift, because so far no single approach numerically
addresses lift creation's entire problem. Bernoulli and Coanda are probably
the most commonly known "incomplete applications" among the pub set; both are
concisely eviscerated (more accurately, bounded) by Dr. McLean in his
conceptual assessment of each's ability to address the physical situation.
Anyhow, fun to contemplate for those so afflicted...

Bob W.
  #17  
Old March 1st 15, 03:27 AM posted to rec.aviation.soaring
Martin Gregorie[_5_]
external usenet poster
 
Posts: 1,234
Default new wingtip design

On Sat, 28 Feb 2015 16:54:40 -0700, BobW wrote:

On 2/28/2015 10:19 AM, Dan Marotta wrote:
I must admit that I didn't read the article thoroughly, but it seemed
to me by looking at the picture that the thing would enhance wingtip
vortices (the Windows spell checker did not like that word, BTW).
Anyway, I thought the idea was to reduce vortices since they're wasted
energy that could be used by the aircraft.

Aero engineers, please chime in.


I had the same off-the-cuff gut reaction when I first looked at it, too.
Upon further cogitation, I'm still uncertain eggzackly what-n-how the
designer was seeking to achieve what I think he was seeking to achieve.
I also noticed the article said he was an aeronautics teacher, so this
may be a case of: Those who can't do, teach!

In any event, I'm not investing my retirement in any company trying to
make and sell these babies...

Bob W.


I had good results with a form of Hoerner tip on my F1A competition
models (wings 2011mn span, 150mm parallel chord centre panels, short tips
tapering to 100mm chord by keeping the TE straight and sweeping the LE
back. The general tip design guidelines I used we

- sweep the LE at least 10 degrees to promotee spanwise flow on the top
surface

- rake the edge of the tip about 30 degrees with a smooth,
rounded join to the LE and a sharp, acute angle join to the TE

- the tip's outside edge should follow the lower surface of the airfoil
with the upper surface smoothly blended down to meet the lower surface
at an acute angle.

The idea was for the spanwise flow to help move the tip vortex out from
the tip while the pointed TE would help stability by localising the tip
vortex.

My wings had carbon D-boxes with open structure behind that. The tips
themselves were carved from block balsa, finish sanded and covered with a
doped-on layer of 25 gsm glass-cloth. It all worked pretty much as I
hoped. The design flew well enough to be competitive and was extremely
stable and well-behaved in all sorts of air. There was an unexpected
bonus too: the glass covered tips were very tough. I lost count of the
number of times those models got overturned after landing and blown down
blacktop runways upside down, but always with remarkably little damage to
the tip blocks.


--
[email protected] | Martin Gregorie
gregorie. | Essex, UK
org |
 




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