A customer lives in an apartment house on the 17th floor. He wants to
use an old Hallicrafters AM and SW radio. He cannot put up a long wire
antenna in the conventional way, however he wants to "weave" a sort of
antenna outside on his terrace, sort of like a web, with insulators to
hold the wire in every bend off ground. In this way he hopes to
achieve the length of a long wire antenna in a confined space. Will
this scheme work? The other option would be to hang a 2 X 4 off the
edge of the terrace and drop a wire down with an insulator on it and
hope that he can secure it to a neighbors terrace several floors
below. Anyone have any thought on this problem. Thanks, Lenny

In a very broad sense, the customer is correct. A 10m wire forms a 20m
half-wave antenna, pretty much regardless of how it's oriented or it snakes
around.

There are books on compact and hidden antennas you might want to look at.

It's not unlike a wing. Almost any surface flat on the bottom and curved on
the top can produce lift.

On Mar 6, 8:17*am, klem kedidelhopper
wrote:
A customer lives in an apartment house on the 17th floor. He wants to
use an old Hallicrafters AM and SW radio. He cannot put up a long wire
antenna in the conventional way, however he wants to "weave" a sort of
antenna outside on his terrace, sort of like a web, with insulators to
hold the wire in every bend off ground. In this way he hopes to
achieve the length of a long wire antenna in a confined space. Will
this scheme work? The other option would be to hang a 2 X 4 off the
edge of the terrace and drop a wire down with an insulator on it and
hope that he can secure it to a neighbors terrace several floors
below. Anyone have any thought on this problem. Thanks, Lenny

What is the railing on the deck, wood or metal? He needs to keep the
wire aeay from any metal.

In article
,
klem kedidelhopper wrote:

he wants to "weave" a sort of
antenna outside on his terrace, sort of like a web, with insulators to
hold the wire in every bend off ground.

Lenny-

This is a case of "try it and it will probably work".

I once lived in an apartment with a balcony that had a railing. Someone
before me had bolted a CB 3/8-24 mirror antenna mount to the rail. I
attached a 40 Meter mobile whip and used it as a transmit antenna. The
Kenwood TS-690SAT had no trouble matching it. It didn't get out very
well but reception was good.

For a general purpose shortwave antenna, a 102 inch CB Whip mounted this
way on the railing, might work quite well. It could stick out away from
the building. He could feed it with Co-Ax cable, or just another long
wire between the whip and the radio's antenna terminal.

Fred

"klem kedidelhopper"

A customer lives in an apartment house on the 17th floor. He wants
to use an old Hallicrafters AM and SW radio.


** For AM broadcast, by far the best is to use a frame aerial.

Heaps of stuff on the net about making them.


He cannot put up a long wire antenna in the conventional way,


** Chances are any SW reception will be very badly affected by RFI from the
thousands of nearby TVs, PCs and other assorted electronic devices using
SMPSs that all radiate interference in the SW band. Only the strongest
signals will be heard OK and them he can pick up on a whip antenna mounted
on a balcony railing.


..... Phil

hr(bob) wrote:
On Mar 6, 8:17 am, klem kedidelhopper
wrote:
A customer lives in an apartment house on the 17th floor. He wants to
use an old Hallicrafters AM and SW radio. He cannot put up a long wire
antenna in the conventional way, however he wants to "weave" a sort of
antenna outside on his terrace, sort of like a web, with insulators to
hold the wire in every bend off ground. In this way he hopes to
achieve the length of a long wire antenna in a confined space. Will
this scheme work? The other option would be to hang a 2 X 4 off the
edge of the terrace and drop a wire down with an insulator on it and
hope that he can secure it to a neighbors terrace several floors
below. Anyone have any thought on this problem. Thanks, Lenny

What is the railing on the deck, wood or metal? He needs to keep the
wire aeay from any metal.

Or use the railing as antenna.

Also, when sort on space, a loop antenna might be usefull.

"William Sommerwerck" wrote in message
...
In a very broad sense, the customer is correct. A 10m wire forms a 20m
half-wave antenna, pretty much regardless of how it's oriented or it
snakes
around.

There are books on compact and hidden antennas you might want to look at.

It's not unlike a wing. Almost any surface flat on the bottom and curved
on
the top can produce lift.



So how come a symmetrical wing, such as might be found on a stunt plane,
still flies, and most asymmetric wings fly quite happily upside down ? :-)

Arfa

"Arfa Daily"

It's not unlike a wing. Almost any surface flat on the bottom and curved
on the top can produce lift.


So how come a symmetrical wing, such as might be found on a stunt plane,
still flies, and most asymmetric wings fly quite happily upside down ?
:-)



** I ask people who *think* they know how a plane flys that same Q.

Stumps them all the time.

Goes to show how simple explanations are often highly flawed.



...... Phil

It's not unlike a wing. Almost any surface flat on the
bottom and curved on the top can produce lift.

So how come a symmetrical wing, such as might be found
on a stunt plane, still flies, and most asymmetric wings fly
quite happily upside down ? :-)

I don't know. But that wasn't the point I was making.

On Sat, 6 Mar 2010 06:17:39 -0800 (PST), klem kedidelhopper
wrote:

A customer lives in an apartment house on the 17th floor. He wants to
use an old Hallicrafters AM and SW radio. He cannot put up a long wire
antenna in the conventional way, however he wants to "weave" a sort of
antenna outside on his terrace, sort of like a web, with insulators to
hold the wire in every bend off ground. In this way he hopes to
achieve the length of a long wire antenna in a confined space. Will
this scheme work? The other option would be to hang a 2 X 4 off the
edge of the terrace and drop a wire down with an insulator on it and
hope that he can secure it to a neighbors terrace several floors
below. Anyone have any thought on this problem. Thanks, Lenny

With just a randomly oriented long wire you will get unpredictable
results.

A better idea would be to get a PVC form of three to six inches and
helically wind the wire. The exact length won't matter because you
do not have a specific frequency in mind. Generally the more wire the
better. Mount it vertically or if you like move it around for the best
reception.

"Phil Allison" wrote in message
...

"Arfa Daily"

It's not unlike a wing. Almost any surface flat on the bottom and curved
on the top can produce lift.


So how come a symmetrical wing, such as might be found on a stunt plane,
still flies, and most asymmetric wings fly quite happily upside down ?
:-)



** I ask people who *think* they know how a plane flys that same Q.

Stumps them all the time.

Goes to show how simple explanations are often highly flawed.



..... Phil



I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies. I
don't really remember the details, but it relied heavily on the wing's angle
of attack into the air, to produce the pressure differential, and hence
lift. I seem to recall that it was the opposite way round from the
'conventional' teaching of increased speed of the air over the top of the
wing reducing the pressure, and that this theory had the attack angle
causing compression under the wing, thereby increasing the pressure to
produce lift. I do, however, remember it saying that air has no
'intelligence', and just because two previously adjacent molecules became
divided above and below the wing, there was nothing to say that they had to
form back up in the same way as they left the back edge of the wing, which
would require the air to move faster over the longer upper surface. I
believe it did say that the air actually does travel faster over the curved
face of the wing, and that the fact that it does, does produce a reduction
in pressure. However, this reduction is small, and only contributes a very
limited amount of lift, compared to the main mechanism that's at work.

Arfa

I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing flies. I
don't really remember the details, but it relied heavily on the wing's
angle
of attack into the air, to produce the pressure differential, and hence
lift. I seem to recall that it was the opposite way round from the
'conventional' teaching of increased speed of the air over the top of the
wing reducing the pressure, and that this theory had the attack angle
causing compression under the wing, thereby increasing the pressure to
produce lift. I do, however, remember it saying that air has no
'intelligence', and just because two previously adjacent molecules became
divided above and below the wing, there was nothing to say that they had
to
form back up in the same way as they left the back edge of the wing, which
would require the air to move faster over the longer upper surface. I
believe it did say that the air actually does travel faster over the
curved
face of the wing, and that the fact that it does, does produce a reduction
in pressure. However, this reduction is small, and only contributes a very
limited amount of lift, compared to the main mechanism that's at work.

I see your reasoning, but I don't think it's right. If the air near the
surface of the wing did not travel faster over the top of the wing, there
would be a buildup of air at the front.

And let's not forget that little experiment where one blows over the top of
a strip of paper, demonstrating, Bernouilli's Law.

Of course, this isn't to say that there is /only one way/ for a wing to
produce lift. But I don't want to get involved in this. Again, the point I
was making has been completely missed. What else is new?

On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

--
Rich Webb Norfolk, VA

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

--
Rich Webb Norfolk, VA

On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.

On Mon, 08 Mar 2010 21:00:51 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.

The Wright's were pretty smart and used a good airfoil design, otherwise
they'd have had to wait for another generation of efficient (power vs
weight) internal combustion engines to make the first flight. Good
designs have less drag and do produce more lift. Poor designs need more
thrust.

Ever fly one of those balsa wood gliders? (Do they even still make
those?) Body & rudder, wings, and elevators all punched out of a flat
sheet. Stick on a prop and a rubber band engine and it does fly.

Rack time ...

--
Rich Webb Norfolk, VA

"AZ Nomad" wrote in message
...
On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb
wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb
wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing
flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.


Tell that to a Harrier pilot.

Horsepower is king.

"AZ Nomad"

An airplane could fly (if not very efficiently) with wings made from
flat sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.


** ********.

Study this page very carefully:

http://www.aviation-history.com/theory/lift.htm



..... Phil

"AZ Nomad" wrote in message
...
On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb
wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb
wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing
flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.



Lift is still lift, whether it comes from the shape of the device or the
angle of attack. When you change the angle you increase the pressure on the
bottom. With a difference in pressure you have lift. As has been said
before, not very efficient, and not straight up, and therefore difficult to
create controlled flight.

Leonard

On Tue, 9 Mar 2010 06:07:42 -0500, Leonard Caillouet wrote:
"AZ Nomad" wrote in message
...
On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb
wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb
wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing
flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.



Lift is still lift, whether it comes from the shape of the device or the
angle of attack. When you change the angle you increase the pressure on the
bottom. With a difference in pressure you have lift. As has been said
before, not very efficient, and not straight up, and therefore difficult to
create controlled flight.

Go build an airplane using just a fin sometime. Video tape and it can
be added to all the other hilarious video footage pre wright brothers
flying machines.

On Tue, 09 Mar 2010 08:50:36 -0600, AZ Nomad
wrote:

On Tue, 9 Mar 2010 06:07:42 -0500, Leonard Caillouet wrote:
"AZ Nomad" wrote in message
...
On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb
wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb
wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing
flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.



Lift is still lift, whether it comes from the shape of the device or the
angle of attack. When you change the angle you increase the pressure on the
bottom. With a difference in pressure you have lift. As has been said
before, not very efficient, and not straight up, and therefore difficult to
create controlled flight.

Go build an airplane using just a fin sometime. Video tape and it can
be added to all the other hilarious video footage pre wright brothers
flying machines.

Grab your video cameras, folks!
http://www.hobbyplace.com/aircraft/toyplanes.php

--
Rich Webb Norfolk, VA

"AZ Nomad" wrote in message
...
On Tue, 9 Mar 2010 06:07:42 -0500, Leonard Caillouet
wrote:
"AZ Nomad" wrote in message
...
On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb

wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb
wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing
flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.



Lift is still lift, whether it comes from the shape of the device or the
angle of attack. When you change the angle you increase the pressure on
the
bottom. With a difference in pressure you have lift. As has been said
before, not very efficient, and not straight up, and therefore difficult
to
create controlled flight.

Go build an airplane using just a fin sometime. Video tape and it can
be added to all the other hilarious video footage pre wright brothers
flying machines.

I never suggested doing so. I simply pointed out that lift is a
differential in air pressure. It is often assumed to apply only to wing
shaped objects, but this is just an assumption. I don't think anyone here
seriously thinks that a straight fin in a good idea for an airplane wing.

Don't try to make an argument were there is none.

Leonard

On Tue, 9 Mar 2010 13:33:43 -0500, Leonard Caillouet wrote:
"AZ Nomad" wrote in message
...
On Tue, 9 Mar 2010 06:07:42 -0500, Leonard Caillouet
wrote:
"AZ Nomad" wrote in message
...
On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb

wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb
wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing
flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.



Lift is still lift, whether it comes from the shape of the device or the
angle of attack. When you change the angle you increase the pressure on
the
bottom. With a difference in pressure you have lift. As has been said
before, not very efficient, and not straight up, and therefore difficult
to
create controlled flight.

Go build an airplane using just a fin sometime. Video tape and it can
be added to all the other hilarious video footage pre wright brothers
flying machines.

I never suggested doing so. I simply pointed out that lift is a
differential in air pressure. It is often assumed to apply only to wing
shaped objects, but this is just an assumption. I don't think anyone here
seriously thinks that a straight fin in a good idea for an airplane wing.

Don't try to make an argument were there is none.

I wasn't the idiot who suggested that waving your hand around from
a car window was an example of lift.

On 3/8/2010 8:53 PM, Arfa Daily wrote:
"Phil wrote in message
...

"Arfa Daily"

It's not unlike a wing. Almost any surface flat on the bottom and curved
on the top can produce lift.


So how come a symmetrical wing, such as might be found on a stunt plane,
still flies, and most asymmetric wings fly quite happily upside down ?
:-)



** I ask people who *think* they know how a plane flys that same Q.

Stumps them all the time.

Goes to show how simple explanations are often highly flawed.



..... Phil



I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies. I
don't really remember the details, but it relied heavily on the wing's angle
of attack into the air, to produce the pressure differential, and hence
lift. I seem to recall that it was the opposite way round from the
'conventional' teaching of increased speed of the air over the top of the
wing reducing the pressure, and that this theory had the attack angle
causing compression under the wing, thereby increasing the pressure to
produce lift. I do, however, remember it saying that air has no
'intelligence', and just because two previously adjacent molecules became
divided above and below the wing, there was nothing to say that they had to
form back up in the same way as they left the back edge of the wing, which
would require the air to move faster over the longer upper surface. I
believe it did say that the air actually does travel faster over the curved
face of the wing, and that the fact that it does, does produce a reduction
in pressure. However, this reduction is small, and only contributes a very
limited amount of lift, compared to the main mechanism that's at work.

Arfa



The Bernoulli principle (the one about the faster air flow corresponding
to lower pressure) is sort of like the second law of thermodynamics (the
one about heat never spontaneously flowing from cold to hot). It's a
shortcut way to get the right answer, but doesn't have the satisfying
feel of a real physical derivation.

BTW by symmetry, symmetric wings require an angle of attack to generate
lift. Otherwise how do they know which way to push?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

"AZ Nomad" wrote in message
...
On Tue, 9 Mar 2010 13:33:43 -0500, Leonard Caillouet
wrote:
"AZ Nomad" wrote in message
...
On Tue, 9 Mar 2010 06:07:42 -0500, Leonard Caillouet
wrote:
"AZ Nomad" wrote in message
...
On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb

wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb
wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing
flies.

It's not really that complex. Didn't you ever, as a kid, hold your
arm
out the car window with your hand flat and "fly" it up and down as
you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from
flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.



Lift is still lift, whether it comes from the shape of the device or the
angle of attack. When you change the angle you increase the pressure on
the
bottom. With a difference in pressure you have lift. As has been said
before, not very efficient, and not straight up, and therefore difficult
to
create controlled flight.

Go build an airplane using just a fin sometime. Video tape and it can
be added to all the other hilarious video footage pre wright brothers
flying machines.

I never suggested doing so. I simply pointed out that lift is a
differential in air pressure. It is often assumed to apply only to wing
shaped objects, but this is just an assumption. I don't think anyone here
seriously thinks that a straight fin in a good idea for an airplane wing.

Don't try to make an argument were there is none.

I wasn't the idiot who suggested that waving your hand around from
a car window was an example of lift.

Actually, it is. It might even be an example of a wing, depending on how
you shape your hand. You appear to be looking for an argument and enjoy
insulting people rather than fostering understanding. Oh, but that is
supposed to be OK on Usenet? Sorry, intelligent discourse can take place
even here.

Leonard

"AZ Nomad"


** ********.

Study this page very carefully:

http://www.aviation-history.com/theory/lift.htm



..... Phil

"AZ Nomad"

** ********.

Study this page very carefully:

http://www.aviation-history.com/theory/lift.htm



..... Phil

"AZ Nomad"

** ********.

Study this page very carefully:

http://www.aviation-history.com/theory/lift.htm



..... Phil

"AZ Nomad"

** ********.

Study this page very carefully:

http://www.aviation-history.com/theory/lift.htm



..... Phil

"Phil Hobbs" wrote in message
...
On 3/8/2010 8:53 PM, Arfa Daily wrote:
"Phil wrote in message
...

"Arfa Daily"

It's not unlike a wing. Almost any surface flat on the bottom and
curved
on the top can produce lift.


So how come a symmetrical wing, such as might be found on a stunt
plane,
still flies, and most asymmetric wings fly quite happily upside down ?
:-)



** I ask people who *think* they know how a plane flys that same Q.

Stumps them all the time.

Goes to show how simple explanations are often highly flawed.



..... Phil



I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing flies.
I
don't really remember the details, but it relied heavily on the wing's
angle
of attack into the air, to produce the pressure differential, and hence
lift. I seem to recall that it was the opposite way round from the
'conventional' teaching of increased speed of the air over the top of the
wing reducing the pressure, and that this theory had the attack angle
causing compression under the wing, thereby increasing the pressure to
produce lift. I do, however, remember it saying that air has no
'intelligence', and just because two previously adjacent molecules became
divided above and below the wing, there was nothing to say that they had
to
form back up in the same way as they left the back edge of the wing,
which
would require the air to move faster over the longer upper surface. I
believe it did say that the air actually does travel faster over the
curved
face of the wing, and that the fact that it does, does produce a
reduction
in pressure. However, this reduction is small, and only contributes a
very
limited amount of lift, compared to the main mechanism that's at work.

Arfa



The Bernoulli principle (the one about the faster air flow corresponding
to lower pressure) is sort of like the second law of thermodynamics (the
one about heat never spontaneously flowing from cold to hot). It's a
shortcut way to get the right answer, but doesn't have the satisfying feel
of a real physical derivation.

BTW by symmetry, symmetric wings require an angle of attack to generate
lift. Otherwise how do they know which way to push?

Cheers

Phil Hobbs


Agreed, and that's the way I understood it. In fact as far as I understand
it, any wing, irrespective of its sectional shape, requires an 'angle of
attack' to fly, and how well a wing flies on any particular aircraft, is a
function of balancing angle of attack against drag so caused, and the power
input required to overcome that drag. I also understood that this was partly
the reason that jet aircraft tend to land and take off with a very 'nose up'
attitude, to increase the angle of attack and hence the amount of lift
whilst the airspeed is relatively low.

Accepting that angle of attack, and the necessary power to drive the wing
through the air being available, is the primary mechanism of lift
generation, then I am having difficulty understanding why some here have
contended that holding your hand out of a moving car window with an attack
angle, is not a valid example of lift generation. Your arm certainly gets
lighter when you do this, so is that not lift ?

Way, waaaay off topic, but a bit of a fun discussion ...

Arfa

On 3/10/2010 1:10 PM, Arfa Daily wrote:
"Phil wrote in message
...
On 3/8/2010 8:53 PM, Arfa Daily wrote:
"Phil wrote in message
...

"Arfa Daily"

It's not unlike a wing. Almost any surface flat on the bottom and
curved
on the top can produce lift.


So how come a symmetrical wing, such as might be found on a stunt
plane,
still flies, and most asymmetric wings fly quite happily upside down ?
:-)



** I ask people who *think* they know how a plane flys that same Q.

Stumps them all the time.

Goes to show how simple explanations are often highly flawed.



..... Phil



I saw an interesting dissertation on this some time back, which put
forward
a much more complex but better believable theory as to how a wing flies.
I
don't really remember the details, but it relied heavily on the wing's
angle
of attack into the air, to produce the pressure differential, and hence
lift. I seem to recall that it was the opposite way round from the
'conventional' teaching of increased speed of the air over the top of the
wing reducing the pressure, and that this theory had the attack angle
causing compression under the wing, thereby increasing the pressure to
produce lift. I do, however, remember it saying that air has no
'intelligence', and just because two previously adjacent molecules became
divided above and below the wing, there was nothing to say that they had
to
form back up in the same way as they left the back edge of the wing,
which
would require the air to move faster over the longer upper surface. I
believe it did say that the air actually does travel faster over the
curved
face of the wing, and that the fact that it does, does produce a
reduction
in pressure. However, this reduction is small, and only contributes a
very
limited amount of lift, compared to the main mechanism that's at work.

Arfa



The Bernoulli principle (the one about the faster air flow corresponding
to lower pressure) is sort of like the second law of thermodynamics (the
one about heat never spontaneously flowing from cold to hot). It's a
shortcut way to get the right answer, but doesn't have the satisfying feel
of a real physical derivation.

BTW by symmetry, symmetric wings require an angle of attack to generate
lift. Otherwise how do they know which way to push?

Cheers

Phil Hobbs


Agreed, and that's the way I understood it. In fact as far as I understand
it, any wing, irrespective of its sectional shape, requires an 'angle of
attack' to fly, and how well a wing flies on any particular aircraft, is a
function of balancing angle of attack against drag so caused, and the power
input required to overcome that drag. I also understood that this was partly
the reason that jet aircraft tend to land and take off with a very 'nose up'
attitude, to increase the angle of attack and hence the amount of lift
whilst the airspeed is relatively low.

Accepting that angle of attack, and the necessary power to drive the wing
through the air being available, is the primary mechanism of lift
generation, then I am having difficulty understanding why some here have
contended that holding your hand out of a moving car window with an attack
angle, is not a valid example of lift generation. Your arm certainly gets
lighter when you do this, so is that not lift ?

Way, waaaay off topic, but a bit of a fun discussion ...

Arfa



Because it's Usenet, and half the fun is the idiotic nitpicking.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

Leonard Caillouet wrote:

AZ Nonad wrote:

I wasn't the idiot who suggested that waving your hand around from
a car window was an example of lift.

Actually, it is. It might even be an example of a wing, depending on how
you shape your hand. You appear to be looking for an argument and enjoy
insulting people rather than fostering understanding. Oh, but that is
supposed to be OK on Usenet? Sorry, intelligent discourse can take place
even here.

Leonard


Too many people are ignoring him on the design newsgroup, so he's
trolling here.


--
Greed is the root of all eBay.

On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:


"Phil Allison" wrote in message
...

"Arfa Daily"

It's not unlike a wing. Almost any surface flat on the bottom and curved
on the top can produce lift.


So how come a symmetrical wing, such as might be found on a stunt plane,
still flies, and most asymmetric wings fly quite happily upside down ?
:-)



** I ask people who *think* they know how a plane flys that same Q.

Stumps them all the time.

Goes to show how simple explanations are often highly flawed.



..... Phil



I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies. I
don't really remember the details, but it relied heavily on the wing's angle
of attack into the air, to produce the pressure differential, and hence
lift. I seem to recall that it was the opposite way round from the
'conventional' teaching of increased speed of the air over the top of the
wing reducing the pressure, and that this theory had the attack angle
causing compression under the wing, thereby increasing the pressure to
produce lift. I do, however, remember it saying that air has no
'intelligence', and just because two previously adjacent molecules became
divided above and below the wing, there was nothing to say that they had to
form back up in the same way as they left the back edge of the wing, which
would require the air to move faster over the longer upper surface. I

Wait a second. The air isn't really moving. It's the plane that is
moving and the air is pretty much standing still, except where the
propeller blows it around but I don't think that's the whole wing.

So the molecules that were together before the plane got there are
still almost together after the wing slices through the air.

believe it did say that the air actually does travel faster over the curved
face of the wing, and that the fact that it does, does produce a reduction
in pressure. However, this reduction is small, and only contributes a very
limited amount of lift, compared to the main mechanism that's at work.

And what's the main mechanism?

Arfa

On Mon, 08 Mar 2010 22:26:11 -0500, Rich Webb
wrote:

On Mon, 08 Mar 2010 21:00:51 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:47:35 -0500, Rich Webb wrote:
On Mon, 08 Mar 2010 20:29:02 -0600, AZ Nomad
wrote:

On Mon, 08 Mar 2010 21:12:26 -0500, Rich Webb wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"
wrote:

I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies.

It's not really that complex. Didn't you ever, as a kid, hold your arm
out the car window with your hand flat and "fly" it up and down as you
changed the angle of attack? That's really all that's necessary. An
airplane could fly (if not very efficiently) with wings made from flat
sheets of plywood.

All you've got there is an inclined plane. You aren't creating lift.

Try it without the car.

The saying goes something like: with enough power, you could fly a
brick. The lift comes from the angle of attack.

Nope. You're just describing a fin.

Lift comes from turbulance on the upper edge causing a vacuum.
Without the airfoil, what you have is pre wright brothers technology
which didn't fly.

The Wright's were pretty smart and used a good airfoil design, otherwise

They were smart. They built a wind tunnel to see which wing shape had
the most lift.

they'd have had to wait for another generation of efficient (power vs
weight) internal combustion engines to make the first flight. Good
designs have less drag and do produce more lift. Poor designs need more
thrust.

Ever fly one of those balsa wood gliders? (Do they even still make
those?)

I think so but maybe not out of wood anymore. Actually funniest home
videos last Sunday had a section on people being hit by their own
planes. All were bigger than what we had, 18" wing span seemed
typical (although maybe people with planes like we had can't afford
video cameras, or aren't so caught up in themselves that they video
little stuff like this.)

?Body & rudder, wings, and elevators all punched out of a flat
sheet.

It's punched out of a flat sheet, but the slot in the fuselage is
curved with the center higher. They at least believe she airfoil
shape is neceessary for somethin to fly well.

Stick on a prop and a rubber band engine and it does fly.

Rack time ...

I don't know what the original topic is, or tangential one for that
matter.. but I do know a lot about airflow over wings.

I can tell you that if two molecules are neighbors, and they take
opposite paths above and below the wing, they do -not- wind up
neighbors on the trailing edge. Look at this image:

http://www.dinosaurtheory.com/wing_air_flow3.jpg

The main source of lift for an airplane is in fact the propeller. The
wing diverts some of the force of the air hitting it in an upward
direction (lift), and some into an impeding force (drag). The wing
(and every other surface) is only designed in an airfoil shape to make
it more efficient.

Whether the plane is moving through the air or the air around the
plane is not important; it's a superposition thing. A small plane with
a STOL (slow takeoff/landing) kit can hover, or even fly backwards, in
a good stiff breeze. The pilot doesn't need to compensate for this at
all (until he gets low enough for the terrain to interrupt the wind).

This is a very poorly understood concept. I've heard engineering
professors botching it up before.

Hope this sheds some light on something.

On Mar 22, 1:00*am, mm wrote:
On Tue, 9 Mar 2010 01:53:39 -0000, "Arfa Daily"



wrote:

"Phil Allison" wrote in message
...

"Arfa Daily"

It's not unlike a wing. Almost any surface flat on the bottom and curved
on the top can produce lift.

So how come a symmetrical wing, such as might be found on a stunt plane,
still flies, and most asymmetric wings fly quite happily upside down ?
:-)

** I ask people who *think* they know how a plane flys that same Q.

Stumps them all the time.

Goes to show how simple explanations are often highly flawed.

..... *Phil

I saw an interesting dissertation on this some time back, which put forward
a much more complex but better believable theory as to how a wing flies. I
don't really remember the details, but it relied heavily on the wing's angle
of attack into the air, to produce the pressure differential, and hence
lift. I seem to recall that it was the opposite way round from the
'conventional' teaching of increased speed of the air over the top of the
wing reducing the pressure, and that this theory had the attack angle
causing compression under the wing, thereby increasing the pressure to
produce lift. I do, however, remember it saying that air has no
'intelligence', and just because two previously adjacent molecules became
divided above and below the wing, there was nothing to say that they had to
form back up in the same way as they left the back edge of the wing, which
would require the air to move faster over the longer upper surface. I

Wait a second. *The air isn't really moving. *It's the plane that is
moving and the air is pretty much standing still, except where the
propeller blows it around but I don't think that's the whole wing.

So the molecules that were together before the plane got there are
still almost together after the wing slices through the air.

believe it did say that the air actually does travel faster over the curved
face of the wing, and that the fact that it does, does produce a reduction
in pressure. However, this reduction is small, and only contributes a very
limited amount of lift, compared to the main mechanism that's at work.

And what's the main mechanism?

Arfa