On 2007-07-28 22:51:58 +0100, John Rumm said:

John Rumm wrote:

I see the use in various areas if its as good as the video. Whats this
E Cut blade for?

These are universal offset (i.e. flush cutting) blades that will cut
wood, plastics, and soft metals:

http://www.axminster.co.uk/product.a... file=1&jump=4

Will

it cut chipboard & copper pipe?

Yup.

In fact I noticed that they also call the wood only versions of this
blade "E-cut"... so chose with care if hacking off a pipe!

Another one that I use quite a bit is the minicut set. This has some
vey small blades which can be used to get into very awkward places.

Message-ID: from
John Rumm contained the following:

"According
to Bernoulli’s Law, greater speed means a lower pressure. The air
pressure under the wing is greater than the air pressure above it. The
result is that the wing, and consequently the whole aeroplane, is pushed
upwards and so the heavier-than-air machine is held up in the air."

Which if you take this as an explanation of flight, how do you explain
the ability of an aircraft to fly upside down?

I must have read this book as a kid (I remember doing most of the
experiments - I never could make a successful hot air balloon that
didn't immediately catch fire) and despite making many model aircraft I
was always confused by the omission of any mention of angle of attack.

--
Geoff Berrow (put thecat out to email)
It's only Usenet, no one dies.
My opinions, not the committee's, mine.
Simple RFDs http://www.ckdog.co.uk/rfdmaker/

The Medway Handyman wrote:
The Medway Handyman wrote:
John Rumm wrote:
You probably thought that about £100+ jigsaws too. Try one first (or
watch some of the videos on the fein site) before judging.

http://www.fein.de/fein-multimaster/...idname=muma_02

Oh & whats the difference between a Multimaster & a Supercut?

About £120 ;-)

Its a slimmer, smaller, lighter version. It has a different tool
clamping mechanism and its own range of blades (although an adaptor is
available to use "ordinary" blades on it (and possibly its blades on an
ordinary multimaster). They also make a bunch of very specialised blades
for this one for things like car glazing removal etc.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 2007-07-29 02:44:37 +0100, John Rumm said:

The Medway Handyman wrote:
The Medway Handyman wrote:
John Rumm wrote:
You probably thought that about £100+ jigsaws too. Try one first (or
watch some of the videos on the fein site) before judging.

http://www.fein.de/fein-multimaster/...idname=muma_02

Oh

& whats the difference between a Multimaster & a Supercut?

About £120 ;-)

Its a slimmer, smaller, lighter version. It has a different tool
clamping mechanism and its own range of blades (although an adaptor is
available to use "ordinary" blades on it (and possibly its blades on an
ordinary multimaster). They also make a bunch of very specialised
blades for this one for things like car glazing removal etc.

I thought that it was the other way round, John

Both tools weigh around 1.2kg

Multimaster spec . says 250W (input)
Supercut spec. says 400W (input)

Andy Hall wrote:

I thought that it was the other way round, John

Both tools weigh around 1.2kg

Multimaster spec . says 250W (input)
Supercut spec. says 400W (input)

Not seen them side by side, but I was under the impression the supercut
was slimmer and designed to be easier to hold etc.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 2007-07-29 06:12:44 +0100, John Rumm said:

Andy Hall wrote:

I thought that it was the other way round, John

Both tools weigh around 1.2kg

Multimaster spec . says 250W (input)
Supercut spec. says 400W (input)

Not seen them side by side, but I was under the impression the supercut
was slimmer and designed to be easier to hold etc.

Might be.

I couldn't find any dimensions.

"John Rumm" wrote in message
...
Roger wrote:

Interesting to note that it includes the same basic error (as in many
books) attributing the flight ability of an aeroplane to the Bernoulli
effect.

Or instructors are still teaching that every day - what is the error
John?

It is certainly a widely held belief that the 2 factors that give lift
are the aerofoil section (Bernoulli effect in action) and the angle of
attack of the wing.

Yup, I would agree with that. You will note however the book omits the
second of those factors - and it is this one that matters.

It simply says:

"According
to Bernoulli’s Law, greater speed means a lower pressure. The air pressure
under the wing is greater than the air pressure above it. The result is
that the wing, and consequently the whole aeroplane, is pushed upwards and
so the heavier-than-air machine is held up in the air."

Which if you take this as an explanation of flight, how do you explain the
ability of an aircraft to fly upside down?

The same theory holds good. Note that aeroplanes designed to routinely fly
upside down tend to have a symetrical aerofoil section so that the wing will
produce lift when inverted just as efficiently. A symetrical section still
relies on Bernoulli for lift.


Again this is a real enough description of the Bernoulli effect, however
in the book it is sighted as *the* way in which the wing gets lift, with
no mention of the far more significant contribution of the reactive force
found by vectoring a huge mass of air downward by virtue of the wing
angle.

It isn't far more significant at all. The Bernoulli effect creates about 2/3
of a wing's lift, ie the upper surface of the wing does about 2/3 of the
work, and the lower about 1/3. This is irrespective of the 'wing angle.'
(angle of attack is the term you need here) You can prove this easily in a
wind tunnel by taking a sheet of thin ply and cutting a wing profile from
it. You will find that presenting it at an angle to the airflow to 'vector
air mass downwards' will produce only a small proportion of the lift that a
similar sized wind profile with a proper aerofoil section is capable of.

Julian.

The message
from "Julian" contains these words:

Which if you take this as an explanation of flight, how do you
explain the
ability of an aircraft to fly upside down?

The same theory holds good. Note that aeroplanes designed to routinely fly
upside down tend to have a symetrical aerofoil section so that the
wing will
produce lift when inverted just as efficiently. A symetrical section still
relies on Bernoulli for lift.

With a symmetrical section you should get the same conditions above and
below the wing so how does it generate lift?


Again this is a real enough description of the Bernoulli effect, however
in the book it is sighted as *the* way in which the wing gets lift, with
no mention of the far more significant contribution of the reactive force
found by vectoring a huge mass of air downward by virtue of the wing
angle.

It isn't far more significant at all. The Bernoulli effect creates
about 2/3
of a wing's lift, ie the upper surface of the wing does about 2/3 of the
work, and the lower about 1/3. This is irrespective of the 'wing angle.'
(angle of attack is the term you need here)

Within reason the more asymmetric the aerofoil section the greater the
lift and the greater the angle of attack likewise so fixed ratios don't
make sense.

You can prove this easily in a
wind tunnel by taking a sheet of thin ply and cutting a wing profile from
it. You will find that presenting it at an angle to the airflow to 'vector
air mass downwards' will produce only a small proportion of the lift that a
similar sized wind profile with a proper aerofoil section is capable of.

Without resorting to a wind tunnel (a paper dart will glide) you can
easily prove you don't need an asymmetric section to get lift. When I
was a child and toys were much simpler you could get crude balsa wood
gliders that had flat sheet wings and they could be trimmed to glide
perfectly but would nose dive if thrown upside down.

--
Roger Chapman

"Roger" wrote in message
k...
The message
from "Julian" contains these words:

Which if you take this as an explanation of flight, how do you
explain the
ability of an aircraft to fly upside down?

The same theory holds good. Note that aeroplanes designed to routinely
fly
upside down tend to have a symetrical aerofoil section so that the
wing will
produce lift when inverted just as efficiently. A symetrical section
still
relies on Bernoulli for lift.

With a symmetrical section you should get the same conditions above and
below the wing so how does it generate lift?

You need a positive angle of attack, when you have this conditions 'above
and below the wing' differ and lift is produced.


Without resorting to a wind tunnel (a paper dart will glide) you can
easily prove you don't need an asymmetric section to get lift. When I
was a child and toys were much simpler you could get crude balsa wood
gliders that had flat sheet wings and they could be trimmed to glide
perfectly but would nose dive if thrown upside down.

Haven't you just answered (all by yourself!) the question you asked above?

Julian.

The message
from "Julian" contains these words:

Which if you take this as an explanation of flight, how do you
explain the
ability of an aircraft to fly upside down?

The same theory holds good. Note that aeroplanes designed to routinely
fly
upside down tend to have a symetrical aerofoil section so that the
wing will
produce lift when inverted just as efficiently. A symetrical section
still
relies on Bernoulli for lift.

With a symmetrical section you should get the same conditions above and
below the wing so how does it generate lift?

You need a positive angle of attack, when you have this conditions 'above
and below the wing' differ and lift is produced.

So when you invert the plane you get a negative angle of attack and the
plane is sucked down.


Without resorting to a wind tunnel (a paper dart will glide) you can
easily prove you don't need an asymmetric section to get lift. When I
was a child and toys were much simpler you could get crude balsa wood
gliders that had flat sheet wings and they could be trimmed to glide
perfectly but would nose dive if thrown upside down.

Haven't you just answered (all by yourself!) the question you asked above?

I suppose you could always argue that any change in pressure in a fluid
involves the Bernoulli effect but there is a world of difference between
the lift generated by a flat plane at an angle and that generated by the
an aerofoil section designed to provide lift.

--
Roger Chapman

The Medway Handyman wrote:
John Rumm wrote:
You probably thought that about £100+ jigsaws too. Try one first (or
watch some of the videos on the fein site) before judging.

http://www.fein.de/fein-multimaster/...idname=muma_02

The moment you pick one up you realise that it bears no resemblance
to a detail sander, although that is a job it will do but
significantly better than any other detail sander I have tried.

OK, I've watched & I'm weakening!

And if you buy one, you'll be obliged to say it's wonderful so you won't
look an idiot.
That's how you sell expensive gadgets.

"Julian" wrote in message
...

"Roger" wrote in message
k...
The message
from "Julian" contains these words:



snip

With a symmetrical section you should get the same conditions above and
below the wing so how does it generate lift?

You need a positive angle of attack, when you have this conditions 'above
and below the wing' differ and lift is produced.


Yep; despite the popular lyrics; it's not " ... the wind beneath my wings
...." but the suction above the wings that takes weight-off-wheels .
The effect is quite marked on aircraft when ,given the correct humidity
conditions, as the aircraft accelerates down th runway -suddenly a 'cloud'
of fog forms above the wings and the airframe 'rotates'.


--

Brian

Julian wrote:

"According
to Bernoulli’s Law, greater speed means a lower pressure. The air pressure
under the wing is greater than the air pressure above it. The result is
that the wing, and consequently the whole aeroplane, is pushed upwards and
so the heavier-than-air machine is held up in the air."

Which if you take this as an explanation of flight, how do you explain the
ability of an aircraft to fly upside down?

The same theory holds good. Note that aeroplanes designed to routinely fly
upside down tend to have a symetrical aerofoil section so that the wing will
produce lift when inverted just as efficiently. A symetrical section still
relies on Bernoulli for lift.

I am not suggesting the Bernoulli effect is in any way mythical, just
that the explanation given in the book is nonsense and does not describe
the correct mechanism. It also seems to fly in the face of the law of
conservation of momentum.

As you state the path length actually makes no difference and a
symmetric or flat aerofoil will still generate lift.

The book states:

"Now the air which passes over the curved upper side of the wing must
travel a much greater distance in the same time than the air which
passes below the wing. That means that the air going over the top of the
wing travels faster than the air beneath."

Which is flawed in two respects: firstly there is no reason why the air
split at the leading edge should remain in alignment at the trailing
edge, and secondly, the actual path length difference does not get close
to accounting for the speed increase of the airflow over the wing. Feed
numbers into the Bernoulli equation based just on that, and you will get
the wrong answer.

Again this is a real enough description of the Bernoulli effect, however
in the book it is sighted as *the* way in which the wing gets lift, with
no mention of the far more significant contribution of the reactive force
found by vectoring a huge mass of air downward by virtue of the wing
angle.

It isn't far more significant at all. The Bernoulli effect creates about 2/3
of a wing's lift, ie the upper surface of the wing does about 2/3 of the
work, and the lower about 1/3. This is irrespective of the 'wing angle.'

The relative contributions will depend on the attack angle and the
aerofoil shape (and many other factors like air speed, & density etc).
The Bernoulli effect enhances the vectoring or turning effect of the
airflow (and as you say, can in the right circumstances generate a
sizeable part of the turning effect). It also explains the influence of
top surface of the aerofoil on the overall lift generated (which a
simplistic model that only looked at the underside of the wing would miss)

(angle of attack is the term you need here) You can prove this easily in a
wind tunnel by taking a sheet of thin ply and cutting a wing profile from
it. You will find that presenting it at an angle to the airflow to 'vector
air mass downwards' will produce only a small proportion of the lift that a
similar sized wind profile with a proper aerofoil section is capable of.

Indeed. An aerofoil section will produce greater turning effect for a
given attack angle.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Roger wrote:

You need a positive angle of attack, when you have this conditions 'above
and below the wing' differ and lift is produced.

So when you invert the plane you get a negative angle of attack and the
plane is sucked down.

Unless you trim it so that the whole attitude of the airframe is steeply
enough raked when inverted to still offer a positive attack angle of the
wing irrespective of its natural upward sloping design when the right
way up.

There are some nice interactive simulators and explanations of this
stuff he

http://www.grc.nasa.gov/WWW/K-12/airplane/short.html


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Sun, 29 Jul 2007 12:00:26 GMT, Stuart Noble
mused:

The Medway Handyman wrote:
John Rumm wrote:
You probably thought that about £100+ jigsaws too. Try one first (or
watch some of the videos on the fein site) before judging.

http://www.fein.de/fein-multimaster/...idname=muma_02

The moment you pick one up you realise that it bears no resemblance
to a detail sander, although that is a job it will do but
significantly better than any other detail sander I have tried.

OK, I've watched & I'm weakening!

And if you buy one, you'll be obliged to say it's wonderful so you won't
look an idiot.

But it is.

That's how you sell expensive gadgets.

I buy things that can pay for themselves. The Multimaster is one of my
cheaper tools, most of the tools I have cost couple of hundred quid up
to around a grand or so.

I suppose to be fair, DIYers will be reading this and they won't be
able to justify spending hundreds of pounds on a tool whereas I can
put it to work and have it pay for itself.
--
Regards,
Stuart.

On 2007-07-29 14:10:01 +0100, Lurch said:

On Sun, 29 Jul 2007 12:00:26 GMT, Stuart Noble
mused:

The Medway Handyman wrote:
John Rumm wrote:
You probably thought that about £100+ jigsaws too. Try one first (or
watch some of the videos on the fein site) before judging.

http://www.fein.de/fein-multimaster/...idname=muma_02

The

moment you pick one up you realise that it bears no resemblance
to a detail sander, although that is a job it will do but
significantly better than any other detail sander I have tried.

OK, I've watched & I'm weakening!

And if you buy one, you'll be obliged to say it's wonderful so you won't
look an idiot.

But it is.

That's how you sell expensive gadgets.

I buy things that can pay for themselves. The Multimaster is one of my
cheaper tools, most of the tools I have cost couple of hundred quid up
to around a grand or so.

I suppose to be fair, DIYers will be reading this and they won't be
able to justify spending hundreds of pounds on a tool whereas I can
put it to work and have it pay for itself.

... and consumables can be built into the customer price.

The message
from John Rumm contains these words:

So when you invert the plane you get a negative angle of attack and the
plane is sucked down.

Unless you trim it so that the whole attitude of the airframe is steeply
enough raked when inverted to still offer a positive attack angle of the
wing irrespective of its natural upward sloping design when the right
way up.

Me being a bit careless with the terminology. I was using 'angle of
attack' as the angle between the centre line of the plane and the centre
line of the wing. If that has a separate definition I have yet to find
it.

--
Roger Chapman

John Rumm wrote:

Interesting to note that it includes the same basic error (as in many
books) attributing the flight ability of an aeroplane to the Bernoulli
effect.


But that is why the shower curtain sucks itself inwards AFAIK.


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

Roger wrote:
The message
from John Rumm contains these words:

So when you invert the plane you get a negative angle of attack and the
plane is sucked down.

Unless you trim it so that the whole attitude of the airframe is steeply
enough raked when inverted to still offer a positive attack angle of the
wing irrespective of its natural upward sloping design when the right
way up.

Me being a bit careless with the terminology. I was using 'angle of
attack' as the angle between the centre line of the plane and the centre
line of the wing. If that has a separate definition I have yet to find
it.

Angle of attack is the angle between the centre line (chord line) of the
wing and the direction of airflow.

The angle between the centre line of the fuselage and the wing is the
angle of incidence.

The angle of incidence is fixed at design time, the angle of attack
varies depending on what the plane is doing and its this that allows a
plane to fly upside down. Increasing the angle of attack increases drag.
At some point, depending on the airfoil section, too high an angle of
attack will cause the air flow to detach from the surface of the wing
causing a stall.

Wikipedia has several good write ups related to this, and can normally
be relied upon for straight factual stuff.

VH.

Message-ID: from The Medway
Handyman contained the following:

But that is why the shower curtain sucks itself inwards AFAIK.

It just does that to be annoying.

--
Geoff Berrow (put thecat out to email)
It's only Usenet, no one dies.
My opinions, not the committee's, mine.
Simple RFDs http://www.ckdog.co.uk/rfdmaker/

"Roger" wrote in message
k...
The message
from "Julian" contains these words:

Which if you take this as an explanation of flight, how do you
explain the
ability of an aircraft to fly upside down?

The same theory holds good. Note that aeroplanes designed to routinely
fly
upside down tend to have a symetrical aerofoil section so that the
wing will
produce lift when inverted just as efficiently. A symetrical section
still
relies on Bernoulli for lift.

With a symmetrical section you should get the same conditions above and
below the wing so how does it generate lift?

You need a positive angle of attack, when you have this conditions 'above
and below the wing' differ and lift is produced.

So when you invert the plane you get a negative angle of attack and the
plane is sucked down.

When inverted the negative angle of attack will produce a force that is now
_upwards_ (the wing is inverted) If the upwards force is vectorially equal
and opposite to the aircraft weight, which always acts downwards, the plane
will fly straight and level inverted.

Julian.

"John Rumm" wrote in message
...

The book states:

"Now the air which passes over the curved upper side of the wing must
travel a much greater distance in the same time than the air which passes
below the wing. That means that the air going over the top of the wing
travels faster than the air beneath."

Which is flawed in two respects: firstly there is no reason why the air
split at the leading edge should remain in alignment at the trailing edge,

There is a good reason, it has to because if it didn't you would either be
creating or destroying matter! Think of it as a continual process, If it
didn't remain in alignment it would have to find someplace else to go....,
what ever passes the leading edge _has_ (by inspection) to pass to the
trailing edge.


and secondly, the actual path length difference does not get close
to accounting for the speed increase of the airflow over the wing. Feed
numbers into the Bernoulli equation based just on that, and you will get
the wrong answer.

I remember a calculation once that showed that the Bernoulli effect on the
upper surface of a Jumbo Jet wing (this was the example used) produced a low
pressure that was equivalent to what a person could achieve by sucking on a
straw, ie next to bugger all. But calculate how many straws could be stood
on a Jumbo wing and you've got the few hundred tons of lift required.



Again this is a real enough description of the Bernoulli effect, however
in the book it is sighted as *the* way in which the wing gets lift, with
no mention of the far more significant contribution of the reactive
force found by vectoring a huge mass of air downward by virtue of the
wing angle.

It isn't far more significant at all. The Bernoulli effect creates about
2/3 of a wing's lift, ie the upper surface of the wing does about 2/3 of
the work, and the lower about 1/3. This is irrespective of the 'wing
angle.'

The relative contributions will depend on the attack angle and the
aerofoil shape

But the relative contributions remain similar, there's no great change.

Julian.

Julian wrote:

Which is flawed in two respects: firstly there is no reason why the air
split at the leading edge should remain in alignment at the trailing edge,

There is a good reason, it has to because if it didn't you would either be
creating or destroying matter! Think of it as a continual process, If it

Don't follow that. Perhaps we are talking at crossed purposes. Have look
at the model he

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

Click the Direction button, then give the wing say 10 degrees of
positive attack. Now slide the rake release point. You should see that
the air that splits at the leading edge does not arrive coincidently at
the trailing edge - the air flowing over the top section gets there
first even though the wing pictured has equal path length.

didn't remain in alignment it would have to find someplace else to go....,
what ever passes the leading edge _has_ (by inspection) to pass to the
trailing edge.

Indeed it does, but it does not have to do so at the same time as the
air which started out adjacent to it at the leading edge of the wing,
but which passed under it rather than over.

The relative contributions will depend on the attack angle and the
aerofoil shape

But the relative contributions remain similar, there's no great change.

Try this one:

http://www.grc.nasa.gov/WWW/K-12/airplane/shape.html

Non variable attack angle, but variable wing shape, and hence
significantly variable lift. Then compare with:

http://www.grc.nasa.gov/WWW/K-12/airplane/incline.html

Hi speed, hi altitude flight will also reduce the Bernoulli contribution
the lift noticeably due to reduced air density.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

The Medway Handyman wrote:
John Rumm wrote:

Interesting to note that it includes the same basic error (as in many
books) attributing the flight ability of an aeroplane to the Bernoulli
effect.


But that is why the shower curtain sucks itself inwards AFAIK.

Yup, and also by air displacement from inside the curtained area.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:
The Medway Handyman wrote:
John Rumm wrote:

Interesting to note that it includes the same basic error (as in
many books) attributing the flight ability of an aeroplane to the
Bernoulli effect.


But that is why the shower curtain sucks itself inwards AFAIK.

Yup, and also by air displacement from inside the curtained area.


Quite a few years ago when I worked for Nilfisk, we did a Buying Agency
exhibition. My oppo from t'north who had many years of experience & was a
glider pilot organised an exhaust air blower for one of the vacs.

Given the high airflow of the Nilfisk vac, this created quite a volume if
air. He bought a beach ball, inflated it & placed it in the airstream so
the airflow was going over the top of the ball.

The airflow caused the ball to spin & remain in the air a good 4' above & 4'
away from the vac.

It looked incredible! Spectators were amazed. The IT stand opposite
actually complained that they had spent £20K on interactice displays & we
got more attention with a 99p beach ball.


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

The Medway Handyman wrote:

The airflow caused the ball to spin & remain in the air a good 4' above & 4'
away from the vac.

It looked incredible! Spectators were amazed. The IT stand opposite
actually complained that they had spent £20K on interactice displays & we
got more attention with a 99p beach ball.

Reminds me of years ago when a mate of mine built a RC model "boat" out
of a 2L coke bottle. It did not so much cruise, as leap in an out of the
water almost uncontrollably (seriously over powered for its size and it
had no proportional throttle control). He would simply turn it on and
throw it (literally) into the water where it would bob about almost
submerged until power was applied. It seemed to upset a number of the
people at the lake who were accustomed to having a small crowd of boys
and dads watching as they piloted their multihull racing boats (in some
cases costing well over £1000!) at great speed, when they were upstaged
by a coke bottle, a RS540 motor and some old camera batteries!

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

"John Rumm" wrote in message
news:46ad11c9$0$1614$ed2619ec@ptn-nntp-

http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

Click the Direction button, then give the wing say 10 degrees of positive
attack. Now slide the rake release point. You should see that the air that
splits at the leading edge does not arrive coincidently at the trailing
edge - the air flowing over the top section gets there first even though
the wing pictured has equal path length.

Bugger, there's nothing to be seen in the 'java simulator' window. I wonder
if it's a site problem or something on my computer?

Have a look here when you have a moment:
http://amasci.com/wing/airfoil.html

Julian.

Julian wrote:

"John Rumm" wrote in message
news:46ad11c9$0$1614$ed2619ec@ptn-nntp-
http://www.grc.nasa.gov/WWW/K-12/airplane/wrong1.html

Click the Direction button, then give the wing say 10 degrees of positive
attack. Now slide the rake release point. You should see that the air that
splits at the leading edge does not arrive coincidently at the trailing
edge - the air flowing over the top section gets there first even though
the wing pictured has equal path length.

Bugger, there's nothing to be seen in the 'java simulator' window. I wonder
if it's a site problem or something on my computer?

If you go he

http://www.java.com/en/download/index.jsp

That will let you install the latest runtime environment for your browser.

(If you are using firefox then check you don't have Java unticked in the
content tab on options...)

Have a look here when you have a moment:
http://amasci.com/wing/airfoil.html

That seems to support what I was saying about the path length explanation.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Nah - best DIY gadget by far is the SO


--
geoff

I thought that saved you from DIY?