Thursday, May 14, 2009

String Tech

It's a pity that Hitler and his gang were such a bunch of vicious, xenophobic bastards.

In an idle moment - of which I have many - I went looking for details of the V-1 flying bomb: the world's first cruise missile. I'm building a 3D model. The stuff I found is extraordinary. There's loads of info on the Web, and though it's fragmentary there's enough to piece together the workings of almost every item in the device.

I was particularly interested in the guidance system. Pictures usually just show a jumble of shapes, and I'd always assumed they used a crude, valve-based equivalent the sort of thing we'd used today. No: there are no active electrical components in it, unless you count the gyro motors and a couple of solenoids - which I don't.

They did the entire control system pneumatically! Pressure is provided by two wire-wound compressed-air balloons. When the course drifts and the gyro tilts, it squeezes one of two pressure lines feeding either side of a piston in a differential cylinder. This pressure imbalance causes the piston to push the rudder left or right. A more delicate barometer arrangement does the same thing to ailerons on the tailplane for altitude. Amazing!

And then there's the pulse-jet itself. No moving parts except a few hundred little spring-steel flaps, and running cheap and dirty wartime gasoline, it was still so good that the US spent ages duplicating it to make a cruise of their own. It developed 3kN of thrust, enough to deliver nearly 1,000 kilos of Amatol the 250 clicks to London.

(A bunch of guys in a Californian extreme sports/dangerous fun group got hold of an original vane assembly and managed to duplicate it using NC machines. They use it for making horribly loud 50Hz noises.)

Many spectacular inventions came out of WWII - the Japanese intercontinental balloon bombs must be the cutest - but the V 1 and 2 are both serious paradigm-shifting technology. Because it practically gave birth to the Space Age, the V2 gets all the credit, but the V-1 solved some horrendous problems using technology we wouldn't touch today. While we can be glad that the Nazis bit off more than they could chew, if you squint a bit you can kinda see why they thought the Germans were a super-race.