…and to add, it helps if you remember that the air wasn’t really moving until it hit the leading edge of the wing.

Then it was accelerated so that its relative speed is reduced as its actual velocity increases. In other words, think backwards, and try to see the relative speed of the ‘moving’ air as resulting from how much it is not being accelerated by interaction with the wing – or more specifically, how that acceleration is being countered by an accelerative force in the other direction caused by bunching of streamlines.

Then if you imagine that higher relative speed, and resultant lower pressure, being sustained for a distance you can see how it need have nothing to do with the longer journey and its about the acceleration and deceleration (relatively) of the air by the distorting streamlines – somehow its easier to picture when you realise you are working backwards, and picture the wing as being propelled through the stationary air at a velocity that will never quite be matched by the relative velocities that create the lift.

YES, it’s complicated, or at least an effort for anyone to get their head around – it’s not just NACA/NASA making it so. No, you don’t need to follow this to get a pilot’s license, but the question was about how it actually works 🙂

Tangmere?

Increasingly rare to find in circulation. Back in the 80’s it seemed a rummage in the magazine pile of any second hand book shop would net a few copies of ‘Aeroplane’. Now.. hardly ever. I think it’s to do with generations – they would be junk from late Grandad’s attic the first time around and a ‘job lot’ or house clearance sold to the bookshop. Now survivors are part of people’s cherished collections, and rarely get ‘job lotted’ out to bookshops or even car boots.

You got a bargain there – people are asking a fiver for just one. And yes, perfect time capsules – and the ads can teach a lot about aircraft manufacture, often being quite literal and illustrated very carefully. If the Germans really were interested in how we made aeroplanes as was (perhaps arrogantly) thought, they would have studied the ads, not the articles!

I often wonder whether the ads were really worth it. Would a manufacturer really choose a DH prop over Rotol for the new design because an ad in ‘Aeroplane’? It’s not like Joe Smith or Sidney Camm would go ‘Oh, de Havilland – not heard of them, let’s give their propellers a try’. Same goes for Dowty hydraulics, and many other prolific and frequent advertisers of the time.

I think the distance thing comes into force in August?

Eye4wings.. Hurricane wings are one of the great mysteries. Yes there are many flying, but if you were to administer a truth drug to those responsible they’d tell you the bits all fitted together to make them slightly different every time. That washout – well spotted. It’s achieved by the front spar tip boom/extension having a ‘drooped’ taper. And it is very subtle – not classic ‘washout’ as it only applies to the rounded tips and not the ‘primary aerofoil’ (and giving the impression of zero incidence when viewed from the side). Now, if you could use that eye to work out the angle off the vertical ‘datum’ on which the plane of the main spar web lies 🙂 Clues – it ain’t vertical, and it ain’t the 2 degree incidence either.. in practice it appears to vary somewhere in between and be how the centre section and its mounting points ‘came together’.

As an aside, originally the wings were bolted to the factory wall, and that was your jig right there!

Steven wh has more or less nailed it.. A lot of wing foils are symmetrical and they lift when you give them an angle of attack. They still need a profile though, as this works to prevent the drag induced pitch-up a flat plate would quickly give. (Kite strings and your arm out the train window also prevent this). In a free-flying body this is done by shaping to keep flow attached as opposed to turbulent.

Bernoulli is all about local acceleration of air .. the air does not know what it’s counterpart on the other side of the foil is doing, and isn’t trying to catch up/slow down so it meets its counterpart molecules at the trailing edge! In fact, as pointed out, it doesn’t, there is a slight ‘stagger’. There are two parts to this. The larger effect is simply that the upper surface air has been speeded up and then slowed. Even if it is moving at the same relative speed at the end as it was initially (the aircraft air speed), it will have ‘got ahead’ during its fast phase – and if that phase is sustained long enough this can easily outweigh the longer journey! You won’t get net thrust, as the air is eventually slowed down again, so its not as contrary to the laws of physics as it first seems. Of course, if you heat the air… you get a Meredith effect.. but I digress.
Then there is a more subtle friction effect, where a ‘flat’ lower surface has slightly more boundary-layer friction drag than the cambered upper surface. What happens at the boundary layer is of no small importance, and is often counter-intuitive. For example, it is quite normal for this layer to flow forward, trailing-edge to leading edge, if only locally.

Yes Sadsack, and that’s another example of the dangers of ‘interpretation’. In the 50’s audiences wanted their war heroes to sound like (or even be) David Niven – and not show any sign of the strain of war. That was history ‘translated’ to suit the culture of the times. Now it puts generation after generation off having any interest in what seems, without context, a posh boy’s jape.

Reading back posts and looking at things ‘in the round’, it looks to me like those in charge of Hendon’s future are not as clueless as it would first appear. Instead they are focussed with laser-like clarity in a digital and entrepreneurial way on their target audience of semi-retarded photophobic crap-technology fetishists with no interest in history or aeroplanes.

It is as though the authorities are slightly apologetic about it being an historic aircraft museum, and feel the pill needs to be sweetened somehow – and are casting around for ways of doing it. ‘Battle of Britain’? Bit old-aeroplaney, that. Best get rid of it.. We could replace it with a Samuel L Jackson theme park, cos he was in a film about planes or sumfink. As long as its nice and digital and entrepreneurial.

I like ‘Bob’. Or Kate, for short.