WW2 naval dazzle-camo 'could beat Taliban RPGs'

Original URL: https://www.theregister.com/2011/06/02/dazzle_vs_rpgs/

Comical claim

Posted in Science, 2nd June 2011 13:14 GMT

Researchers at Bristol uni say they have performed experiments indicating that if British troops were to use the "dazzle camouflage" favoured for warships in the World Wars on their vehicles in Afghanistan, this would make them harder to hit with RPG anti-armour rockets, a favourite Taliban weapon.

Dr Nick Scott-Samuel, psychologist and lead researcher on the study, wrote:

The effect should obtain... on modern, low-tech battlefields where handheld weapons are fired from short ranges against moving vehicles. We show that in a typical situation involving an RPG7 attack on a Land Rover the reduction in perceived speed would be sufficient to make the grenade miss where it was aimed by about a metre, which could be the difference between survival or otherwise for the occupants of the vehicle.

Can this be true?

Let's look at the details. The study involved showing test subjects different patterns moving across a computer screen, in an attempt to see whether the nature of the pattern affected the subject's perception of it. According to Scott-Samuel and his colleagues, high-contrast zigzag or check patterns moving fast made their subjects underestimate speeds consistently.

However, the threshold at which this was seen involves pretty high speeds. The subjects only began to get their speed estimates wrong when the dazzle-cam patterns were tracking past at 20 degrees/second or more, which in the case of a vehicle 70m away means it must be travelling at 55 mph or more.

The researchers go on to say that this will make it noticeably harder to hit such a vehicle with an RPG* shoulder-fired rocket, a common weapon in use by the Taliban:

Dazzle patterning should offer some protection from such devices. The effect size observed for check and zigzag patterns at this speed is an error of circa 7 per cent. An approximate calculation, based on the best available knowledge of the flight characteristics of a typical weapon, shows that the grenade takes around 0.5 s to reach a target at 70 m [22]; in 0.5 s a 90 km/h [55 mph] vehicle moves 12.5 m, and so a 7 per cent error is about 90 cm. In other words, the missile would hit around 1 m behind where it was aimed, a difference which may be sufficient to prevent loss of life.

Come off it

There are quite a few problems with this. Afghanistan is very rough country, mostly not suited to high-speed driving off road. The fastest British military vehicle in use there, the "Jackal" gun truck, is rated for an absolute maximum offroad speed of 80 kph, not 90, and must mainly travel much more slowly. Even on-road, average speeds (and this is in the relatively peaceful northwest - pdf here - not the war-torn south) are seldom more than 30 kph.

In the more realistic case of a vehicle moving at 30 kph, an RPG shooter would need to be within a perilous 25 metres of his target for the dazzle camo to have any effect on him. Even assuming such a bold and sneaky attacker, the resulting error would be barely 9cm, not worth wasting paint to obtain.

Even in the rather fantastical case of vehicles hurtling along mostly dreadful Afghan roads at 90kph+, the error produced by dazzle-cam - already unimpressive at 90cm, against targets which are 5m long and more - will naturally shrink fast as the range shortens in from 70m, due to decreased flight time of the rocket. And beyond 70m range, the vehicle needs to be going at completely ridiculous speeds for the dazzle camo to work on the shooter's brain.

In summary, dazzle camouflage would produce a very marginal, not really very useful effect in the unusual case of vehicles travelling at implausibly high speeds in a very narrow range band - say 60-80m at best.

And dazzle camouflage, of course, is not camouflage at all in the usual sense: it doesn't make things harder to spot in the first place, indeed it makes them easier to see because it requires high-contrast patterns. The idea behind dazzle-cam is not to avoid being seen, but to make oneself harder to hit once one has been seen. It was originally meant to prevent German submarines getting an accurate idea of a warship's range, speed and heading, so causing difficulties in getting a hit with a visually aimed dumb torpedo.

From this study it becomes apparent that it never worked in the matter of causing a speed-estimation error, as warships don't go fast enough for the effect to kick in. It's also quite plain that in fact - contrary to the Bristol researchers' conclusions - that it has pretty much zero utility in the case of RPGs and military vehicles, certainly not enough to justify dispensing with actual camouflage effects designed to make a vehicle harder to see in the first place.

Almost unbelievably, given how basic the mathematics is, this idea has not only been published in the academic press (here, by PLoS ONE) but taken up by actual MoD scientists. The "TARIAN" anti-RPG textile protection - itself a very cunning idea - has been tested (pdf) in a dazzle pattern by the Defence Science and Technology Laboratories recently (see pic above). ®

Bootnote

*Generally held to stand for Ruchnoy (Handheld) or Raketniy (Rocket) Protivotankoviy (Anti-tank) Granatomet (Grenade Launcher), in Russian. Usually shortened to Rocket Propelled Grenade in English. Could refer to any of a number of similar-looking shoulder-fired rocket systems of Soviet/Russian design and manufactured in many countries. The 1960s-vintage RPG7 is the most commonly enountered, normally firing basic shaped charge anti-armour projectiles.