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Backwash Causes Lift?



 
 
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  #121  
Old October 4th 07, 07:51 PM posted to rec.aviation.piloting
[email protected]
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Posts: 1,130
Default Backwash Causes Lift?

On Oct 4, 10:47 am, Le Chaud Lapin wrote:

I could probably explain VOR to a 10-year-old, without ever mentioning
things like counters, angular frequency, anisotropic radiation,
frequency bands, sub-carriers, convolution, etc....and my explanation
would still be correct.



I doubt it. The ten-year-old, and most flight students,
have absolutely no frame of reference to understand any of this in any
depth. I teach a College course on Aircraft Systems, and I have to
keep things really simple so they can grasp a few basics. If you are
an electrical engineer, and I've had a few in my classes, we can get
more into the workings of the VOR, but we leave all the others yawning
and wondering if this is going to be on the final exam.
When we come to hydraulics, we talk about pressure, volume
and area and relate that to what we experience as kids playing with a
garden hose. The same analogy can be used to a limited extent when
explaining Ohm's Law. But now I encounter kids who grew up in
highrises and never squirted their sisters with a hose, so they have
more difficulty. Too much information, not enough relationship to
previous bases because there are none.
You have no frame of reference yet. When you start getting
into violent departure stalls, skidding-turn spins, accelerated
stalls, spirals and the like, the sounds and forces start to make the
textbook stuff real. Sure, Jeppesen isn't always right. I haven't
found a textbook yet that doesn't have some glaring errors, and the
one I use in the Systems class has at least four that I have to issue
corrections on in the syllabus. And the writers of texts have found
that they don't sell the books that go into thousands of pages of
detail; the students have neither the inclination for it nor the time.
They have careers in other fields. So the textbook authors keep it
really simple in the hope that the student will be piqued enough to
dig further on his own. Most don't.
You an argue this as long as you want, like Mx, but it's all
book-learnin' and when the ground starts to come up at you real quick
it won't matter one bit. You WILL want to understand AOA and where you
went wrong.

Dan
Flight Instructor
Aircraft Maintenance Engineer


  #122  
Old October 4th 07, 08:42 PM posted to rec.aviation.piloting
Le Chaud Lapin
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Posts: 291
Default Backwash Causes Lift?

On Oct 4, 1:51 pm, wrote:
On Oct 4, 10:47 am, Le Chaud Lapin wrote:

I could probably explain VOR to a 10-year-old, without ever mentioning
things like counters, angular frequency, anisotropic radiation,
frequency bands, sub-carriers, convolution, etc....and my explanation
would still be correct.


I doubt it. The ten-year-old, and most flight students,
have absolutely no frame of reference to understand any of this in any
depth. I teach a College course on Aircraft Systems, and I have to
keep things really simple so they can grasp a few basics. If you are
an electrical engineer, and I've had a few in my classes, we can get
more into the workings of the VOR, but we leave all the others yawning
and wondering if this is going to be on the final exam.
When we come to hydraulics, we talk about pressure, volume
and area and relate that to what we experience as kids playing with a
garden hose. The same analogy can be used to a limited extent when
explaining Ohm's Law. But now I encounter kids who grew up in
highrises and never squirted their sisters with a hose, so they have
more difficulty. Too much information, not enough relationship to
previous bases because there are none.
You have no frame of reference yet. When you start getting
into violent departure stalls, skidding-turn spins, accelerated
stalls, spirals and the like, the sounds and forces start to make the
textbook stuff real. Sure, Jeppesen isn't always right. I haven't
found a textbook yet that doesn't have some glaring errors, and the
one I use in the Systems class has at least four that I have to issue
corrections on in the syllabus. And the writers of texts have found
that they don't sell the books that go into thousands of pages of
detail; the students have neither the inclination for it nor the time.
They have careers in other fields. So the textbook authors keep it
really simple in the hope that the student will be piqued enough to
dig further on his own. Most don't.
You an argue this as long as you want, like Mx, but it's all
book-learnin' and when the ground starts to come up at you real quick
it won't matter one bit. You WILL want to understand AOA and where you
went wrong.


I agree with everything you wrote except this last part and the part
about the 10-year-old. I have teaching experience myself in
electrical engineering, and mathematics, computer science, ...all, non-
trivial. I have found that very many complex things can be taught to
people while still remaining honest. Certainly there might not be
utlization of Maxwell's equations or partial-differential equations,
or red-black trees, but insight can be instilled that will give the
student an understanding that is both intutive and accurate. As the
student matures, the depth of understanding might increase, but it can
at least remain true. Schools try hard to do this, but since there
are so many students in class at once, each with different proclivity
to learn, the curriculum, by necessity, quickly suffers from rote
drill, as you hinted at. I remember being introduced to notion of
sqare-root of negative number in elementrary school. Then middle
school. Then again in high school. I never really understod them in
middle school because the teachers would not allow that. All the
students were in monkey mode. I also remember when I first did long
division, I and wanted to move on to what was next, and the teachers
would not allow it. I was forced to do hundreds of long-division
problems, one after the other, like a pencil monkey, even though it
was quite apparent what was going on. It was their way of keeping me
occupied.

This was OK for square-root of -1.

I do not think it is OK for flying. I want theory and the practice,
because with flying, I think it is more relevant. I don't want to be
in the cockpit flying around my friends and their children harboring
the secret that regarded the KT as an impediment to me having some fun
yankin' and bankin'. It's irresponsible. And if there is a crash due
to pilot error because of shallow understanding...

....that's simply unacceptable in my book, especially when I have
passengers.

-Le Chaud Lapin-

  #123  
Old October 4th 07, 10:27 PM posted to rec.aviation.piloting
Paul Riley
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Posts: 42
Default Backwash Causes Lift?

"Dudley Henriques" wrote in message
...
TheSmokingGnu wrote:
Dudley Henriques wrote:
Crash Lander wrote:
I'd like to see what his thoughts are on String Theory.
LOL.

I'm sure he'd most likely say that twine was better :-))


What, and discount the obvious implications that Duct Tape has on modern
thinking?

TheSmokingGnu


Ah, duct tape!! Where would aviation be without it ?

--
Dudley Henriques


Hey, don't knock duct tape( we called it speed tape G). Kept water out of
my wing tank in Vietnam (Bird Dog) years ago. .50 cal rounds do a nasty job,
even on self sealing tanks. :-)))))

What the hey, even with one tank, for 2 hours, I still could fly the thing.
And did, for about 2 weeks.
:-)))))))))

Paul


  #124  
Old October 5th 07, 12:23 AM posted to rec.aviation.piloting
Crash Lander[_1_]
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Posts: 233
Default Backwash Causes Lift?

"Mxsmanic" wrote in message
...
Crash Lander writes:

I'd like to see what his thoughts are on String Theory.


String theory is a theory based on math rather than physical reality.



And we all know math has absolutely nothing to do with physical reality eh?
Crash Lander
--
Straight and Level Down Under.
http://www.straightandleveldownunder.net/


  #125  
Old October 5th 07, 12:26 AM posted to rec.aviation.piloting
Tina
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Posts: 500
Default Backwash Causes Lift?

Of course, but the specific statement I wanted made clear had to do
with getting conservation of momentum from Newton's relationship
between force, mass, and acceleration. The OP claimed to be an
engineer, he was suggesting something I thought was unlikely and you
demonstrated that nicely.

  #126  
Old October 5th 07, 12:29 AM posted to rec.aviation.piloting
Tina
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Posts: 500
Default Backwash Causes Lift?

I thought it was called 100 kt tape, but if it walks like a duct and
talks like a . . . .


I'll have another glass of wine now..

  #127  
Old October 5th 07, 12:31 AM posted to rec.aviation.piloting
Dudley Henriques[_2_]
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Posts: 2,546
Default Backwash Causes Lift?

Tina wrote:
I thought it was called 100 kt tape, but if it walks like a duct and
talks like a . . . .


I'll have another glass of wine now..



Ouch!!! Could it be that Shakespeare was right?

--
Dudley Henriques
  #128  
Old October 5th 07, 12:48 AM posted to rec.aviation.piloting
Jim Logajan
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Posts: 1,958
Default Backwash Causes Lift?

Tina wrote:
Of course, but the specific statement I wanted made clear had to do
with getting conservation of momentum from Newton's relationship
between force, mass, and acceleration. The OP claimed to be an
engineer, he was suggesting something I thought was unlikely and you
demonstrated that nicely.


Didn't he say he was an electronics engineer? Unless he's doing work on
electromechanical devices I can see how one can get rusty on dynamics.

I'm not sure questions regarding lift belong in a piloting group anyway.
Fluid dynamics is a particularly difficult subject because it is easy to
overlook things, such as: if a wing accelerates air downward, then
according to conservation of momentum some other mass must be accelerated
upward.
  #129  
Old October 5th 07, 12:53 AM posted to rec.aviation.piloting
Bertie the Bunyip
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Default Backwash Causes Lift?


Mxsmanic wrote:
Le Chaud Lapin writes:

Yes, I am. It's a combination of many things taking place at once.
Vacuum generation by the forward motion of the wing is one of them.


Gravity does that, not the forward motion of the wing. Without gravity, the
wing would simply move upwards until the effective angle of attack were no
longer positive.


Good grief.


Bertie

  #130  
Old October 5th 07, 12:54 AM posted to rec.aviation.piloting
Bertie the Bunyip
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Posts: 316
Default Backwash Causes Lift?


Le Chaud Lapin wrote:
On Oct 3, 9:26 pm, TheSmokingGnu
wrote:
Le Chaud Lapin wrote:
You can have lift of an object with no Bernoulli. It's simple vector
addition.


1. You are talking about nature's abhorrence of a vacuum.
2. Vacuum abhorrence is not lift.
3. Airplanes do not generate lift as a result of vacuum abhorrence.
----------
Conclusion: you are not talking about how aircraft generate lift.


Yes, I am. It's a combination of many things taking place at once.
Vacuum generation by the forward motion of the wing is one of them.


Enjoying yourself there Anthony_

i know I am!

Bwaahwahwhahwhahwhahwhahwhahwhahwhha!


Bertie

 




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