Things you always wanted to know the answer to [Vol. 3]

[XFDreamer]

Aeroplane wings. I understand how they work. They create lift hence the plane flys.

So how can a plane fly upside down?

Surely the shape of the wing should send it smashing into the ground.

[gl20]

Lift is not just down to wing profile but also angle of attack ie with the plane right side up and in nose up attitude the overall lift is increased since it increases the distance air over the top side of the wing. If the plane is inverted you can still achieve this by pushing the nose down (meaning it will point to the sky). The total lift won't be as much as it is offset by the natural lift (or downforce) of the now inverted wing but still enough lift for the plane to stay up. Plus on an aerobatic plan the wing assymetry is reduced (or you can even have a symmetric wing profile) so that lift is almost entirely down to nose pitch.

I think..

[red_slr]

Trimmed for level flight....

[walm]

gl20 said:

Lift is not just down to wing profile but also angle of attack ie with the plane right side up and in nose up attitude the overall lift is increased since it increases the distance air over the top side of the wing. If the plane is inverted you can still achieve this by pushing the nose down (meaning it will point to the sky). The total lift won't be as much as it is offset by the natural lift (or downforce) of the now inverted wing but still enough lift for the plane to stay up. Plus on an aerobatic plan the wing assymetry is reduced (or you can even have a symmetric wing profile) so that lift is almost entirely down to nose pitch.

I think..

All that "distance air travels over the wing causes lift" is just poor schoolboy physics. It's true but it is a very minimal part of what makes a plane fly.
Firstly what makes the plane fly is the conveyor belt as we all know.
The second most important part is the fact you have two huge bloody great pieces of aluminium sending a column of air directly down.
Try sticking your hand out of a moving car and angling it 45deg to the horizontal - your arm will want to shoot upwards.

This is why they extend huge flaps out the back of the wing which catch even more air and send it down.

Hence when upside down you can just stick the nose UP and keep flying - just like you do when taking off.

[Nom de ploom]

Apologies for morbiditiy but..

Q. How do Explosions kill or injure people? I understand that shrapnel and flying debris can maim and injure and kill but when it is reported that "x no. of people were killed by the blast" how does that happen?

is it the shock wave ? what actually is the force of the blast? is there any footage of an experiment that can demonstrate this?

again apologies for the nature of the question but I have genuinely always wanted to know.

ta

[Hugo a Gogo]

shock wave moves the bits inside your body just as much as things outside

Imagine shaking a large black forest gateau inside a sealed tin

that's your guts and brain inside your ribs and skull

bashed and bleeding, arteries torn away etc

[gwm]

Hugo a Gogo said:

Imagine shaking a large black forest gateau inside a sealed tin

A macabre but succinct example.

Similar to this, in that the force from a pressure wave does the same:

https://www.youtube.com/watch?v=qsp-nrf_8KQ

[Nom de ploom]

Hugo a Gogo said:

shock wave moves the bits inside your body just as much as things outside

Imagine shaking a large black forest gateau inside a sealed tin

that's your guts and brain inside your ribs and skull

bashed and bleeding, arteries torn away etc

what is the physics behind the shockwave ? is is based on the explosives creating outward air pressure?

thanks for the answer though

[Hugo a Gogo]

yes, the wave of high and low air pressure

here's a wiki about a common 'blast injury' that doesn't have surface effects
https://en.wikipedia.org/wiki/Pulmonary_contusion

[davhill]

My mistake...moved.

Edited by davhill on Thursday 13th August 14:01

[Issi]

gwm said:

Hugo a Gogo said:

Imagine shaking a large black forest gateau inside a sealed tin

A macabre but succinct example.

Similar to this, in that the force from a pressure wave does the same:

https://www.youtube.com/watch?v=qsp-nrf_8KQ

This is also what happens when you jump from a high bridge into water, I always thought that you were knocked out and drowned, but then I read a book about the Golden Gate Bridge and it stated that 99% of the time, the jumpers were killed by having their organs reorganised when they impacted the water.

[Dr Jekyll]

1) How do you know whether you are showing persistence in the face of setbacks (essential for success) or hopeless perseverance in a doomed endeavour (insanity)?


2) Why is Lady Jane Grey not referred to as Queen Jane the first, but the equally uncrowned Edward is referred to as King Edward VIII?

[singlecoil]

Dr Jekyll said:

2) Why is Lady Jane Grey not referred to as Queen Jane the first, but the equally uncrowned Edward is referred to as King Edward VIII?

I guess that was partly history being written by the victors, and partly because it could be said that she was never actually Queen, because the current Act of Succession made Mary the Queen, followed by Elizabeth (assuming Mary didn't have children).

[SpeckledJim]

Dr Jekyll said:

1) How do you know whether you are showing persistence in the face of setbacks (essential for success) or hopeless perseverance in a doomed endeavour (insanity)?

Only in retrospect. The dividing line between genius and insanity being defined only by success.

[Shaolin]

Do successful people have dreams (while asleep) of successes? and do our anxiety dreams cause us to have less self confidence?

I was having difficulty sleeping last night and started thinking about this. Most (all?) people have dreams where you are trying to do something, get somewhere and it keeps going wrong, you're delayed, go the wrong way, lose stuff etc. etc. at the end you've failed to do the straightforward thing you were trying to do. So do we retain this as a memory of the experience we didn't actually have thereby making us more cautious and less confident, as we might with a real experience? Conversely if I had dreams where I was always a success, would it make me more self confident? I don't know about anyone else but I never have a dream where everything turns out far better than I ever expected and I end up as some kind on hero in my own head - which is the sort I'd choose.

[TwigtheWonderkid]

Dr Jekyll said:

1) How do you know whether you are showing persistence in the face of setbacks (essential for success) or hopeless perseverance in a doomed endeavour (insanity)?

Winners never quit and quitters never win. But conversely, those who never win and never quit are idiots.

[StevieBee]

Dr Jekyll said:

1) How do you know whether you are showing persistence in the face of setbacks (essential for success) or hopeless perseverance in a doomed endeavour (insanity)?

The latter is what is more commonly known as being "a Labour supporter".

[Muddle238]

[quote=walm]

The second most important part is the fact you have two huge bloody great pieces of aluminium sending a column of air directly down.
Try sticking your hand out of a moving car and angling it 45deg to the horizontal - your arm will want to shoot upwards.

This is why they extend huge flaps out the back of the wing which catch even more air and send it down.
quote]

Not sure if serious...

[rohrl]

Muddle238 said:

walm said:

The second most important part is the fact you have two huge bloody great pieces of aluminium sending a column of air directly down.
Try sticking your hand out of a moving car and angling it 45deg to the horizontal - your arm will want to shoot upwards.

This is why they extend huge flaps out the back of the wing which catch even more air and send it down.

Not sure if serious...

It is serious.

Wings create lift because there is higher air pressure beneath them than above but what you've been told about lift occurring because the top surface of the wing is longer than the bottom is not the full story.

http://www.cam.ac.uk/research/news/how-wings-reall...

[Mastiff]

SpeckledJim said:

Dr Jekyll said:

1) How do you know whether you are showing persistence in the face of setbacks (essential for success) or hopeless perseverance in a doomed endeavour (insanity)?

Only in retrospect. The dividing line between genius and insanity being defined only by success.

Great question - great answer!