Projectile Protectors – Half II: Ballistic Helmets

In the primary a part of this deep dive into ballistic safety, we talked about physique armor. What about defending your dome? Let’s take a short look again on the historical past of helmets to higher perceive their worth.

The primary documented use of helmets in fight was present in historic Sumeria and Akkadian civilization, each from the area we might name Mesopotamia, circa 2300 BCE. The earliest bronze helmets are reported to have come from the Mycenae in 1700 BCE, and these Greeks had been additionally believed to be the inventors of the primary plate armor set.

Use of fight helmets was prolific inside the Historical Greek and Roman Empires, at first being manufactured from leather-based and finally varied varieties of metallic and metal-alloys — initially leather-based and brass, then bronze and iron. As weaponry turned extra subtle, so too did the necessity for extra strong protections of soldier’s heads. Navy use of helmets was initially employed to forestall the wearer from cuts, arrows, and low-velocity musketry.

Ultimately, within the seventeenth century, the usage of army helmets declined as rifled firearms entered the battlefield. Whereas some holdouts, like Napoleonic period cavalry, nonetheless wore ornate helmets, they served extra as standing symbols than safety from ballistic threats. Nevertheless, within the early twentieth century firstly of World Struggle I, the widespread use of battlefield artillery resurrected the necessity for helmets — metal ones. Fashionable battlefield hazards included lateral frag from artillery and falling particles, in addition to bullets (the latter wouldn’t be defeated till a lot later within the late twentieth and early twenty first century).

After metal, fashionable battlefield troopers wore PASGT (Personnel Armor System for Floor Troops) and related helmets crafted from Kevlar, Aramid, or the same artificial fiber. Extra not too long ago, they’re crafted from ultra-high-density polyethylene. The light-weight but ultra-strong supplies shield in opposition to lateral frag and shrapnel, many pistol rounds, and even rifle rounds, as we are going to talk about on this article.

One other main adaptation has been safety from non-ballistic threats, like a concussive shockwave, in addition to the inner padding. Ample padding inside a helmet helps soak up the inertia from ballistic threats and mitigate backface deformation (extra on this later), in addition to making the helmet extra comfy to put on.

Above: The Crye Precision AirFrame makes use of a novel two-piece overlapping shell that gives improved air flow. Crye says it may possibly additionally “scale back the damaging results of explosive blast waves.”

Helmets vs. Physique Armor: How Are They Totally different?

Each cease bullets and shrapnel, however there are some inherent variations. Whereas some physique armor could also be curved, it has nowhere close to the curvature of a helmet, which primarily must be a partial sphere. This creates challenges with any ballistic materials and is the place the artwork and science of ballistic safety meet. To be able to have a strong armor system in your head, there must be consistency within the layers and density all through the armor system in order to not have any failure factors.

“If you’d like a quarter-inch helmet, it must be a quarter-inch all the best way round. With the fabrication course of, with out crown-reinforcements the thickness of your helmet will range from crown [of the head] to sides. We add crown reinforcements to assist forestall that,” Dub Robertson, retired Grasp Sgt. (USMC), Plant Supervisor for Exhausting Head Veterans, elaborated.

It is a delicate stability, Robertson stated, in that should you add extra plies (extra layers) otherwise you don’t take note of this stability, you may get beauty deformations like wrinkles and bubbles, which can or might not result in a ballistic failure. Particularly, he stated you need the within of the helmet to be as clean as doable. That is why helmets that defeat ballistic threats are a lot tougher to manufacture than non-ballistic helmets.

Director of Analysis & Growth of Engineering at HighCom Ed Clark defined their proprietary helmet fabrication course of: “The know-how we make the most of is the XTclave, which is our proprietary know-how. It’s a special methodology of consolidating the supplies collectively to create the helmet. As you in all probability are conscious, when these uncooked supplies are available, they’re on a roll they usually’re comparatively versatile. They’re successfully like a giant sheet of material. We then put these materials onto a ply-cutting machine to kind the specified shapes, then stack a number of layers of fabric on prime of each other.

This materials stack is then put right into a pre-forming press to offer it an preliminary form. Then, we do a ultimate consolidation stage via our XTclave, which imparts the total consolidation strain and temperature into the shell. Historically, most producers will make the most of solely a press, so in impact they’re making use of the consolidation strain solely via one aircraft.”

What’s extra, the ultra-high-molecular-weight polyethylene (UHMWPE), colloquially referred to as poly, doesn’t paint effectively. Not like armor, helmets are sometimes worn outdoors of a service and are uncovered to the weather, so the outside end is a vital consideration. That is the place “skins” are available.

“Sometimes, skins are an aramid materials, aka Kevlar. [Hard Head Veterans] usually do one pores and skin interior layer, and one pores and skin outer layer. Clearly, utilizing aramid helps with the ballistic properties of the helmet. We do know some corporations on the market are utilizing carbon fiber; they do the ‘guts’ of the helmet in [UHMW]PE, however their first or second pores and skin is carbon fiber. We’ve seen some movies of them capturing a helmet with one of these a configuration, and whereas there isn’t a dent within the helmet, because it helps with compression, there isn’t a ballistic safety supplied from carbon fiber.

It helps with blunt impression, because of the lack of compression within the materials, however has no ballistic safety benefits, so we haven’t used it in our helmets,” Robertson from Exhausting Head Veterans defined on a name. Additionally, carbon fiber is fairly costly, which provides to the price of the helmet.

Helmets are about as excessive of a curve as you’re going to get and usually are not as easy as one thing like urgent physique armor — even curved plates. Fabrication processes just like the proprietary XTclave use a fluid medium to switch strain, which works effectively when creating issues with compound curves and sophisticated geometries. Nevertheless, different customary strategies of fabrication, comparable to layering plies of UHMWPE, are nonetheless sturdy. So long as the producer understands the dynamics of crown reinforcement and it passes ballistic testing, you have to be good to go.

Testing Protocols for Helmets

Ballistic helmets undergo the same testing protocol to physique armor, with some slight nuanced variations. A lot of the helmets in the marketplace are solely rated to defeat pistol rounds, which technically is a Degree II or IIA ranking. Per NIJ 0106.01 for ballistic helmets, to acquire a Kind II ranking, the helmet should defeat high-velocity pistol-caliber rounds such because the .357 Magnum or high-velocity 9mm (+P or +P+).

One firm who I interviewed for this piece manufactures a rifle rated helmet — HighCom Safety’s RCH helmet. The RCH is rated in opposition to widespread rifle threats and boasts a Degree III ranking, in a position to defeat 7.26×39, 5.56×45 XM193, and even the hard-hitting 7.62×51 NATO.

One other consideration with regards to ballistic helmets is safety from shrapnel, sometimes called lateral frag. The benchmark for that is MIL-STD-662F, and this exams in opposition to totally different weights of shrapnel that one would see on the battlefield or in an space of operation, going from 2 grains to 44 grains in weight, at various velocities.

The MIL-STD-662F framework is utilized to grade armor — that features physique armor, armored seats for plane and floor automobiles, crew station armor on army vessels, plane armor, bulkheads, tactical shelters, and even “clear armor” like windshields, shields, or home windows. The RCH abides by the MIL-STD-662F along with NIJ 0101.06 Degree III Score.

Contemplating the intense curvature of a helmet, the NIJ’s testing is extremely in-depth, and requires totally different hit angles to go — fundamental aircraft, coronal aircraft, sagittal aircraft, and likewise takes into consideration the angle of assault when testing. There’s an NIJ customary for Ballistic Helmets printed if you wish to go deep on the specs, however discuss with the desk for an excerpt.

Above: Exhausting Head Veterans (HHV) latest ATE Lite helmets are made in Sweetwater, Texas, utilizing a mix of UHMWPE and aramid fibers.

What About Backface Deformation?

As with physique armor, backface deformation is prime of thoughts for ballistic helmets as effectively. Whereas there’s extra “padding” with a helmet — each the structural “impression layer” and the softer padding that’s used for consolation — backface deformation is a non-trivial consideration with ballistic helmets. This began from a analysis and improvement paper from the U.S. Military the place 25mm was the usual, however many corporations at this time have gotten right down to 15mm at max, and in some circumstances 8mm or much less with high-velocity pistol rounds, effectively beneath the U.S. Authorities requirements.

Per HHV’s spec sheet on their HPE helmet, which I had the prospect to check, the backface deformation of a 9mm 124-grain spherical screaming at over 1,400 ft per second — far above most manufacturing unit hundreds — is at max 15mm on the crown, and solely 8mm behind the top.

This deformation is usually not seen until you peel off the protecting padding of the helmet post-gunshot anyway, however it’s comforting (as comfy as you may get with getting shot within the head) to know that the construction of the helmet will deform solely about ⅓ of an inch.

“Typically, we get helmets again for a dimension trade, and we discover the impression pads are out of there. The impression pads are there for a purpose! They’re particularly designed to scale back backface deformation. The consolation pads aren’t even concerned within the testing, we simply ship the helmet and the impression pads,” Robertson said.

Helmet Weight: It Issues!

Contemplating the human head itself weighs about 8 kilos, and each inch you progress your head ahead from vertical alignment functionally provides 10 kilos to your dome, any ballistic helmet you place in your head will must be light-weight so as so that you can be fight or mission efficient. That is simply as necessary, if no more necessary than physique armor being light-weight. Helmet weight has been confirmed in research to have an effect on cognitive efficiency. When in a hostile engagement, your most beneficial weapon just isn’t your rifle or sidearm, however your mind; helmet weight and cognitive fatigue are correlated.

Furthermore, even the pressure that’s positioned in your neck impacts cognitive efficiency. There are additionally muscular concerns as a number of research have discovered that the heavier the helmet, the extra muscular fatigue and/or threat of damage whereas working within the area.

“There’s a huge drive towards light-weight safety not too long ago, and it’s changing into increasingly more obvious with numerous armed forces … As forces have gotten extra superior, they’re utilizing extra gear to help — headsets, NVGs, augmented actuality. All that gear is including weight. And if it’s happening the top, it’s placing extra load on the top, which suggests your endurance isn’t going to be so long as you’d like, and also you may undergo neck trauma down the road.

So, taking what we time period ‘lifeless weight’ out of a helmet shell is a profit as a result of it means you’ll be able to both put extra gear again onto your operator’s head, otherwise you’re permitting them to put on it for longer,” Clark of HighCom defined, underscoring the significance and validity of the beforehand talked about research.

Above: Oregon Ballistic Laboratories (OBL) additionally exams helmets based on NIJ requirements. Every helmet is examined from quite a lot of angles.

So … What Helmet Ought to You Purchase?

Similar to with physique armor, the helmet that’s best for you is the one that matches your wants and price range. In case you don’t want ballistic safety, an unarmored “bump helmet” gives fundamental impression safety and the flexibility to put on head-mounted equipment like night time imaginative and prescient. In case you’re not working the place you’ll be able to anticipate to see rifle hearth and lateral frag, or simply desire a layer of safety in your most beneficial weapon (your mind), a pistol-rated NIJ Degree II helmet could also be good for you, and can solely run you a couple of hundred {dollars}.

If you’d like one thing that may cease incoming hearth from an AK and solely weigh a few kilos, you’re in luck — they make these now. Simply be sensible concerning the threats you’re more likely to face and keep in mind that increased ranges of safety at all times include not less than a couple of minor trade-offs.

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Written by Alexander Castiglione