Tag Archives: channel 4

A Brush with Base Jumping

Base jumper in the Lauterbrunnen Valley, Switzerland (Photo: Tim Jones)

I see from the TV listings that Channel 4 (UK) will tomorrow be airing  The Men Who Jump off Buildings: a documentary about the extreme sport of base jumping.  Launching from Buildings, Antennas, Spans, Earth (hence BASE), base jumping practitioners have only seconds to control their descent  and deploy a parachute.   Jumps from buildings and cliffs are particularly demanding due to the danger of hitting something sideways on the way down.

Base jumper in Lauterbrunnen Valley (Photo:Tim Jones)
Base jumper in Lauterbrunnen Valley (Photo:Tim Jones,Darkroommatter.com)

While the Channel 4 show promises to focus more on jumps from buildings, it reminds me of a base jump from a cliff side I witnessed in 2007, in Switzerland’s Lauterbrunnen Valley.  The rapid-fire sequence of photos I took at the time should convince you that stamp collecting isn’t such a bad hobby after all.

I later discovered Lauterbrunnen is something of a base jumping hot-spot, famous for the quality of the jumps, but also for the number of related deaths in recent years.

The sequence of 16 pictures in the gallery below shows the various stages of the jump, including the free-fall glide and chute deployment; the main chute is activated by a smaller chute the jumper holds and throws out at the critical moment.

Although the guy in the pictures landed safe and sound – I had a chat with him later – the sequence  shows him fighting to unravel a tangled harness.  Jumpers say every jump is different, so an ability to think quickly on the spot is as important as understanding the theory.

Lauterbrunnen valley (photo:Tim Jones)
Lauterbrunnen Valley (photo:Tim Jones, Darkroommatter.com)

The timing and manner of the chute’s release depends on many factors, including the jumper’s velocity, which in some cases may be below the terminal velocity of around 120 mph.  It goes without saying that the time available to avoid objects and adjust parachutes is severely limited.

Apart from one holiday paragliding experience in the Med., I’ve only worn a parachute while flying gliders – and thankfully never had to use it.  And for now, exhilarating as I’m sure base jumping is, I think I’ll stick to walking up mountains rather than jumping off them.

Of Blitz and Bomb Shelters

Watching the last episode of Tony Robinson’s ‘Blitz Street’ on Channel 4 this week has prompted a few thoughts and surprising memories.

Children made homeless in the London Blitz (Wikimedia Commons)

The four-part series revisited the intensive ‘Blitz’ bombing of Britain during the Second World War by recreating a wartime street and subjecting it to progressively larger explosions, simulating the range of bombs and missiles delivered by the Nazis.  The real Blitz bombing was focused on London, but also other cities including: Liverpool, Hull, Coventry, and the city where I was later raised – Leicester.

The show was framed as a serious science experiment that would, as well as being entertaining, generate new data for historians.  To that end, the houses were wired with pressure sensors to measure the intensity of the blasts, and the associated destruction was captured with high speed photography.

For example, readings taken inside a recreated domestic Anderson Shelter, constructed from corrugated steel and earth, revealed how under certain bombing conditions the pressure wave would be sufficient to kill the occupants, consistent with contemporary reports of whole families being found externally unscathed but dead from internal injuries.   Under other conditions, the test explosions suggested that simply hiding under the stairs had offered adequate protection.

Amazingly, a bottle of milk parked outside one of the houses survived the entire simulated campaign, ranging from the explosion of a 50kg High Explosive (HE) bomb, right through to a simulated V2 rocket impact.

Well, what can you say?  Great television.  And that surviving bottle of milk was a gift to the producers.  For sure, some will criticise various points of historic content and scientific accuracy.  Viewers have commented on the under-representation of Hull as the second most bombed city after London; and I was bemused at the placement of the V2 simulated charge behind an earth bank that seemed to guarantee it wouldn’t totally obliterate the set.  Others might find the whole thing an unnecessary waste of building materials and explosives.

However the popular verdict washes out, I thought the show’s mix of social history with science and technology successfully outweighed any failings.  Here we saw one of the more negative applications of science and technology in context: Science Communication, right?  But more so, a graphic raising of awareness that war isn’t just something that happens to others on CNN.

Beyond the politically incorrect schoolboy/girl appeal of blowing things up, Blitz Street got me digging deeper into the science behind the show, looking out my old university notes on flow simulation, super-sonic pressure wave propagation and nozzle design (re the V2).

On a completely different tack, the show reminded me of the many happy (formative?) hours I’d spent as a teenager inside an air-raid shelter.

How come?  I may be old enough to have benefited from real chemistry sets and the relaxed authority that accommodated them, but I certainly wasn’t around in the Second World War. I did however grow up assuming everyone had a WWII surface air-raid shelter in their back garden, like this one at my parents home in Leicester.

air-raid shelter
Second World War surface air-raid shelter

I’ve always known this cube, with its 14 inch thick brick walls and reinforced concrete ceiling as simply ‘The Shelter’.

air-raid shelter
Walls are about 14" thick

When the family moved here in the seventies, the interior was still in immediate post-war condition, including wooden bunk supports for two, maybe four max, persons.  To protect from lime, the concrete ceiling had been lined with fascinating newspapers of the period, discovered when I converted The Shelter to a photographic darkroom, re-papering it with pages from Amateur Photographer Magazine.

At the age of twelve or so, The Shelter became my first chemistry laboratory.  Minimal ventilation via perforated bricks at the top of each thick wall meant that reactions that were exothermic or likely to generate noxious gases were relegated to the annexed greenhouse.  For example, anything where chlorine or oxides of nitrogen were produced, or compounds were combined with acids or oxidants; and anything involving organic compounds.  All these were better suited to the fume-cupboard environment of the greenhouse.

air-raid shelter
Concrete lintel above entrance

An interesting design feature in the wall at right-angles to the main entrance, is a sort of escape hatch comprising a two foot square of bricks where the cement has been replaced with plain sand.   The idea, I presume, was that if the house got bombed and fell onto the shelter, the occupants, safe inside, could kick out the bricks on the adjacent wall.  It’s been mortared up since, but you can still see the outline in the photo.  Originally, an iron bar extended out from the hatch that an external rescuer could pull on to release the brickwork.

Air-raid shelter emergency exit
Air-raid shelter emergency exit (under concrete lintel)

Now of course I’m keen to know how my Shelter would have fared against Tony Robinson’s bombs – something to be investigated when I find an appropriate (=free) fluid dynamics package.

And from a social history perspective, I’m intrigued as to why the house had it’s own surface air-raid shelter in the first place.  A scan of GoogleEarth suggests none of the neighbours have anything similar; and it’s not the sort of structure that could be easily or inexpensively removed.  So more research needed there.

The house wasn’t situated next to a munitions factory or similar target; it’s just one house in a row of similar suburban dwellings.  Maybe the owner was just nervous enough, and had the cash, to go one better than the standard Anderson shelter.  I’ve heard of similar domestic shelters associated with homes where military personnel were billeted.  A US Airborne division was stationed in the city, so maybe that’s the reason.  Either way, it was more than paranoia.  According to The Leicester Chronicler, two hundred and fifty homes in Leicester were completely destroyed by bombing.  A map of all bombs dropped on Leicester during WWII is here at Wartimeleicestershire.com.

Anyhow, looks like Channel 4 at least succeeded in inspiring a nostalgic ramble;  make of it what you will.