Night Moves

Throughout its long history, the US Army tended to fight during the day, and only fight at night when forced to do so. This was doctrine all the way through the Vietnam War. The thinking was that the confusion of trying to fight at night negated any benefits of concealment and surprise. A review of most US Army night operations tended to support this. One incident that comes to mind is a regimental attack in the closing days of the Tunisian campaign in North Africa in WWII. The regiment jumped off from the line of departure on time, but became disoriented in the confusing terrain. They stormed their “objective” to find no resistance whatsoever. Why? The hill the assaulted was the same one they’d jumped off from. It took them all day to get reorganized. They tried it again the next night. And the same thing happened.

Things got somewhat better over the years, but for the most part, the Army made its attacks the same way they’d done them since the Revolution- at dawn.  But cedeing the initiative at night carried a heavy burden. For instance, in Vietnam, the Viet Cong and the North Vietnamese Army were able to move at night with little concern that they would be interdicted.  Letting the enemy roam around unimpeded for half the time wasn’t a winning strategy. An even bigger impetus was in Europe. Facing the massive Soviet armies to the east, the Army and NATO could ill afford to let the Soviets move and fight at night. A major initiative was put in place to “own the night”. Training was a large part of this, but emerging technologies would be a key enabler. The ability to see clearly at night would revolutionize how our Army fought.

There are three main technologies available to provide night vision- active infrared, passive (thermal) infrared, and image (or light) intensification. Active infra-red was the first technology used. In fact, it was used in the closing days of WWII in Okinawa. The M3 sniperscope was attached to a modified M2 carbine. A special lamp on top of the weapon projected an invisible beam of infrared light. A special scope mounted below the lamp could see the light. It was pretty crude, but good enough to find infiltrators out to its maximum range of about 70 yards.

M3 Sniperscope
M3 Sniperscope

As you can see, the system had some obvious drawbacks, prime among them that the system was far too bulky for more than specialized use. The other big drawback was that the sytem wasn’t passive. It wouldn’t take long for our enemies to develop their own scopes that could see the beam. And once that happened, using the sniperscope would be about as stealthy as running around with a flashlight. Active infrared would be used for several applications for many years, but its shortcomings meant it wouldn’t be the wave of the future for small arms or for infantry units.

Passive, or thermal infrared imaging is widely used by all branches of the service. When you see youtube videos of Apaches taking out insurgents in Iraq or Afghanistan, the black and white footage is from the thermal sensors onboard. Thermal sights work by measuring the difference in temperature radiated by various objects. Fortunately, most militarily significant objects, like people and tanks, radiate more heat than the average background. Thermal is great because it is totally passive and works well day or night. The problem from an infantry point of view is that the system is too large to be mounted on a rifle or machine gun. It takes a substantial mount such as a vehicle or aircraft, and a large power supply.

That leaves imaging intensification. Early image intensification systems were often called “Starlight Scopes” because that’s just what they were. Starlight scopes use the ambient light provided by starlight, moonlight and light pollution, which is then multiplied via  a series of fiber optics, prisms and lenses and electronic components to provide a visible, if monochromatic, presentation.  An early starlight scope was the AN/PVS-2.

pvs2

The PVS-2 was small enough to mount on an M-16 (if just barely) and under the right conditons could provide visibility to the effective range of the rifle (roughly 300 meters).

Now, the PVS-2 worked, but there was still plenty of room for improvement. First, it was too big. Second, the batteries didn’t last very long. And third, if a sudden source of illumination popped up, say a flare, or a fire, or an explosion, the image would be “washed out” by too much light. The answer was the PVS-4, which was pretty  much the standard night sight when I joined the Army. Each rifle squad would have two PVS-4s. The image was much clearer, and the lighter sight made it much easier to use.

PVS-4
PVS-4

But the PVS-4 didn’t solve the essential issue, how to turn night into day. For that, you needed to give soldiers the ability to see in the dark, all the time. That’s where night vision goggles came in. Basically, they work the same way, but are mounted on the head of the soldier. Early NVGs were somewhat cumbersome, and quite delicate. When I enlisted, the standard NVG was the PVS-5.

an-pvs-5-dvic576

You could walk at night, read a map, drive a vehicle, or even fly a plane using these.  Later, the much improved PVS-7 series came into use. The have much better clarity, and instead of using two tubes, use one tube split for two eyepieces. They are much lighter, and yet far more rugged. Early PVS-7s used a special battery size not available on the open market. The were also worn using a cumbersome harness worn under the standard helmet. Later, the Army adapted the -7s to use commercial batteries (AA) and developed a special bracket that is permenantly mounted to the soldiers helmet. The goggles can be quickly clipped on or removed from the bracket.

PVS-7
PVS-7

Almost there. The PVS-7 was pretty much everything the Army wanted except for one nagging issue. You couldn’t aim your weapon while wearing them.  The answer to that was something you are all familiar with- the laser pointer. By mounting a simple laser that shoots a beam of invisible, near infrared light, night fighting was revolutionized. Near infrared light shows up just fine in NVGs. The simple PAQ-4 aiming light would put a “death dot” on the target. You just looked through the goggles, walked the dot onto the target, and squeezed the trigger.

PAQ-4
PAQ-4

About half the soldiers in rifle squad will have NVGs normally. In some units, virtually all soldiers will have them. My own experience with them was generally pretty good. Truth be told tho, I rarely wore them. I carried them, sure, but most nights, there’s enough natural illumination to move around. Looking through NVGs can be quite disconcerting, since you are essentially viewing the world through a soda straw. The lack of peripheral vision can lead to dizziness and a lack of situational awareness. I would usually wear my goggles around my neck, only using them to further investigate something that caught my interest.  Also, we didn’t have the helmet brackets back when I was in. The harness was quite uncomfortable and rarely fit well. Finally, I’m something of a Luddite.

The Army is pretty happy with the PVS-7/PAQ-4 combo, but is still working to develop newer, lighter night vision systems. There’s a great deal of effort being put into making thermal sights small enough to mount on the M-16 family of rifles. Thermal sights aren’t blocked by smoke or dust like current NVGs. But cost and complexity are still major issues.

3 thoughts on “Night Moves”

  1. Would it be possible to somehow hybrid the systems? Mix image intensification and thermal sights so you can get the best of both worlds?

  2. On vehicle mounted systems, maybe. But they’re having a heck of a time coming up with a lightweight thermal system for small arms. Right now, image intensification works for most uses. It’ll be a while before we see a lot of lightweight thermal systems.

  3. As of September, 2010, I have seen a hybrid capability that uses image intensification and thermal. You can use one or the other, or overlay a thermal image over the other. And, it is small enough and light enough to go on a helmet mount. I don’t know if the army is going to buy it, but they could. It was awesome.

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