Steel Hornets: Inside Ukraine’s Amazon For Drone Bombs

This year Ukraine will build more than a million drones, and import at least a million more. Most will be small FPV kamikazes, while others will be bombers. This is creating a huge demand for new drone munitions which is being met by startups like Ukraine’s Steel Hornets.

Steel Hornets, “a private manufacturer of weapons systems for unmanned aircraft systems”, is essentially a mail-order drone bomb company sending munitions directly to users. They have been remarkably successful, with a string of innovative designs developed in consultation with drone operators at the front line. (Incidentally, they should not be confused with Ukraine’s similarly-named Wild Hornets who make the drones).

Artillery shells for Ukraine cost around $2,000 each; Steel Hornets’ munitions are much, much cheaper but still capable of destroying tanks and other targets. Steel Hornets has a very different approach to traditional arms makers. It might just be the closest thing to an Amazon AMZN for drone munitions: rather than fulfilling massive government contracts they ship tiny batches to retail customers on a grand scale. And this approach may be just as revolutionary as Amazon was in its day.

This Is Not Your Grandfather’s RPG

FPV kamikaze drones have typically been armed with warheads taken from RPG rockets. For more than six decades, the 85mm PG-7 has seen action everywhere from Vietnam to Somalia to Afghanistan. And while it was produced in large numbers, supplies are not endless; a recent Ukrainian video shows the unboxing of a PG-7 originally manufactured in 1968.

These warheads are becoming scarcer. And while they are very effective against armored vehicles, FPVs are increasingly used to target individual Russian footsoldiers. Operators want something with more of an antipersonnel effect.

Small quadcopter bombers, often DJI Mavics, are typically armed with modified grenades. Early on the most common drone bomb was a modified Russian 30mm Vog-17, usually fired from a grenade launcher, but this has no effect on armored vehicles and needs good aiming to harm personnel on foot. Drones often drop hand grenades, including the old Ukrainian F1 – which resembles the classic U.S. Mk2 ‘Pineapple’ grenade of WWII, the more modern RGD-5, and imported German DM51 and U.S. M67 grenades.

One of the most prized drone bombs is the ‘Golden Egg’, the U.S. M433 40mm grenade, another one usually fired from a launcher which combines anti-armor and anti-personnel effects. None of these is designed to be dropped from a drone. Soldiers make field modifications to the fusing so they work as aerial bombs, but this is not 100% reliable.

In addition there are a wide array of home-made drone bombs, some of them using soda cans as bodies, the more advanced with 3D-printed tailfins. There are also makeshift incendiaries, Molotov cocktails and thermobaric blast weapons.

What drone operators want is something cheap and reliable which can be easily acquired in large numbers without the need for complicated work. And this is what Steel Hornets provide, with a wide range of drone munitions, small and large bombs for quadcopters from consumer-grade Mavics to Baba Yaga heavy bombers, plus of course a selection of warheads for FPV kamikazes.

But there is a twist.

*Explosive Not Included

Steel Hornets provide their munitions without explosive filling or detonator. This makes them safe to handle and easy to distribute via the postal service, allowing Steel Hornets to supply drone operators quickly and efficiently wherever they are.

To arm the munition, the operator fits it with a standard military MD5M or KD8A detonator, devices the size of a thumb drive available by the million. Then also pack the bomb body with plastic explosive.

A spokesman for Steel Hornets said that explosive was typically drawn from supplies for demolition work, or scavenged from other munitions. For example, the UR-77 Meteorite demining system uses line charges filled with over 1,450 kilos / 3,200 pounds of plastic explosive to blast a path through minefields. One line charge contains enough explosives for several hundred drone bombs.

Steel Hornets are also exploring other ways for users to source explosive filler. With commercial plastic explosive costing just a few dollars a pound (the U.S Army pays $22 a pound for small demolition charges but they do not do things cheaply), it should not add much to the cost of the finished munition.

You might reasonably wonder what exactly it is that Steel Hornets are selling. After all, what is there to a bomb apart from the explosive and detonator?

And the answer is: the smart part.

Smart Bombs

Steel Hornets produce three types of drone bomb: armor-piercing shaped charges for use against tanks and other vehicles, fragmentation weapons effective against personnel, and dual-purpose munitions which combine both functions. All three require considerable design, so munitions from Steel Hornets give a real advantage over garage-made or field-improvised alternatives.

The aerodynamic plastic bomb casings are 3D printed with fins to ensure they fall in straight. They are also well balanced so they can be carried without affecting the stable flight of the drone.

“It’s not the cheapest, but it’s a very flexible manufacturing method,” says the Steel Hornets spokesman.

It allows them to make in very small batches, and also to change the design instantly with no need for re-tooling. But the more significant element is inside.

Anti-armor munitions are built around a shaped charge. This is a hollow cone, usually made of copper, with explosives packed around it, When the explosive detonates, it blasts the copper into a narrow, high-speed jet of metal capable of punching through armor plate.

Shaped charge technology dates back to Charles Munroe documented the principle back in 1888, while he was working at the U.S. Naval Torpedo Station at Newport, Rhode Island. Monroe discovered the effect accidentally when blocks of explosive stamped with “USN” left a reversed image of the letters on a steel plate they were detonated against. He went on to reproduce the ‘Munroe Effect’ by deliberately creating cavities in explosive charges, and found it was greatly enhanced by lining the cavity with metal.

Since then the design of shaped charge liners has become a whole field of study in itself and there are many different designs with conical, hemispherical and trumpet-shaped liners of different geometries made of different types of metal.

For example Steel Hornet’s BP 75mm replacement for the standard PG-7 warhead weighs 850 grams/ 30 ounces, somewhat lighter than the original. In tests Steel Hornets’ shaped charge with a copper liner penetrated 180mm / 7 inches of steel plate. This is less than the original which can go through 260mm/ 10 inches of armor, but this is not seen as a problem.

“We are seeking a compromise between weight, size, and cost,” the Steel Hornets spokesman told Forbes. “Additionally, we are making the shaped charge jet thicker, which often results in more confident penetration, albeit slightly reducing the penetration thickness.”

But their 850-gram weapon is sufficient to disable a tank by striking outside the frontal arc where armor this thinner. Even Russia’s vaunted T-90M, which boasts the equivalent of more than 500 mm/ 20 inches of armor at the front, has less than 150mm of armor at the sides and rear making it vulnerable to Steel Hornet’s design.

“T-90s have already been destroyed by it,” confirms the spokesman.

The miniature tank busters are a bargain at $14 a time. As with other Steel Hornets products the minimum order is a box of five. This gives an idea of how different they are to traditional arms companies dealing in orders of thousands.

Anti-Personnel Effects

The PG-7 anti-tank warhead does not produce much shrapnel and is not an effective antipersonnel weapon. Targets can walk away from a near miss. Steel Hornet’s alternative is a fragmentation casing filled with ball bearings.

Again, there is a whole field of study behind maximizing the lethality of shrapnel and ensuring that the cloud of fragments is the right size and shape. The exact size, number and distribution of these determines how effective a weapon is. In the U.S. this has given rise to the computer modelling known as Lethality Enhanced Ordnance developed by Orbital ATK, later acquired by Northrop Grumman NOC . This is the technology which produced munitions like the rockets fired by HiMARS with its 182,000 tungsten ball bearings of a particular diameter carefully arranged around an explosive core.

Steel Hornets may not have the same facilities, but they have done a lot of experimentation, plus they have the advantage of instant feedback from the field. After several iterations they have a design called Thermos. This weighs 1200 grams / 42 ounces when fully loaded but combines armor penetration with shrapnel effect, all for $17. For pure lightweight antipersonnel effect there is the smaller 300-gram/11-ounce WT300, from dropping from quadcopters, at just $3 a time including a long probe to ensure it explodes well above ground level.

Steel Hornets also make the even more lethal ‘flying claymore’ for FPV drones. Rather than detonating on impact, this is triggered by operator command as it approaches the target, and fires a carefully calculated spray of shrapnel over a wide area. But you will not find details on their web site.

“For obvious reasons, we don't disclose information about our remotely detonated explosive ordnance,” says the spokesman.

Other innovative products are similarly only discussed directly with customers rather than shared openly.

A Light Industry With Heavy Results

Steel Hornets could hardly be more different from the conventional arms business. Rather than the world of heavy machinery and brass shell casings, theirs is a culture of 3D-printing and lightweight composites. While traditional companies take years and millions of dollars to develop new designs, they can turn around a new product in weeks on a shoestring budget.

The market is changing fast. While Mavic-type consumer quadcopters were the main bombers just a few months ago, now most bomb drops are by FPV-type drones, which can deliver much heavier munitions.

“Carriers are becoming larger and larger, “says the spokesman. “And the fleet of drone planes is developing very rapidly.”

Economies of scale drive traditional munition production, but Steel Hornets work with small batches. They are effectively a retail operation, which is why a comparison with Amazon is apt. And rather than relying on a few huge suppliers with long lead times for munitions – hence the mad scramble to acquire artillery ammunition — a collection of small startups like Steel Hornets could meet Ukraine’s demand for millions of drone munitions. Getting artillery shells from other countries may still be a problem, but these are munitions that can be made locally with minimal capital expenditure.

Just as small, agile drones are starting to look like the future of war, small agile suppliers may be the future of defense procurement. And Steel Hornets, with their growing experience in the toughest of conditions, are leading the way.