Russians Alarmed By Ukraine’s Fence Post Drone Bomb

The new Ukrainianbomb is a crude but effective bunker buster Russian Telegram

Russian social media has been circulating images of a Ukrainian drone bomb which is square with a metal point like the ground spike for a fence post. This is a penetrating weapon, as a sticker on the bomb proclaims, and it has Russian military bloggers worried. Now nowhere is safe.

FPVs and drone bombing have driven Russian forces underground into bunkers and forced them to cover roads and facilities with nets, wire cages and steel mesh. A few weeks ago Russian reports started circulating of a new drone bomb punching through such defenses. The new images suggest that this weapon is now being produced at scale, and a Ukrainian video shows it in action.

Ukraine operates a fleet of heavy bomber multicopters of various types, notably the Vampire, but also Kazhan (“Bat”), Heavy Shot and Nemesis. The Russians call them by the generic term of Baba Yaga. Vampire can deliver a 33-pound bombload to a target ten miles away.

Multicopter bombers typically drop modified mortar bombs or anti-tank mines and similar repurposed munitions, depending on the target. But there are some purpose-built munitions for specific tasks, like this one.

US GBU-57 bomb - note penetrating nose and the slender profile compared to general purpose bombs AFP via Getty Images

Penetrating bombs date back to WWII when they were developed to hit heavily protected targets like battleships and concrete fortifications. The U.S. revived the concept 1980’s with the 2,000-pound BLU-109 “Bunker Buster” first of a series of ever more powerful up to the mighty 30,000-pound Massive Ordnance Penetrator.

These bombs differ from standard or “general purpose” bombs in three ways: they have a streamlined penetrating nose, reinforced to withstand impact; they tend to be long and narrow to concentrate force in a small area and reduce resistance; and they feature a delayed action fuse, so the bomb goes off after it had broken through protection. The fence post bomb, primitive as it looks, follows the same pattern.

The nose is designed to withstand the impact force of being driven into the ground. Since fence post anchors already exist, there was no need to reinvent them. Comparison with other items in the image, notably the Tolsen 300 mm hacksaw, suggests that the design is based on spike for a standard 100mm fence post. Commercial fence spikes are stamped from sheet metal and machine welded whereas this example seems to be hand-welded, and the metal appears to be thicker than a normal fence spike. If this started as a product from a hardware store it has been heavily modified in a garage workshop.

A rough calculation suggests that, assuming a 25-pound munition dopped from a few hundred feet, the penetrator will go through a foot of hard-packed dirt or four feet of soft soil.

The new munitions are now apparently being produced in significant numbers Russian Telegram via X

Bunkers are typically constructed with a log roof (more resilient than concrete), covered with a foot or more of dirt to absorb blast and shrapnel. The penetrator will go through the earth covering and may find a gap in the log roofing.

The other key feature is the delayed action fuse. Most drone bombs are impact fused and will be set off by hitting the ground, or can be prematurely detonated when they strike a metal cage or netting. A delayed fuse means the bomb does not go off until it has penetrated.

A Ukrainaian video shows one of the mini bunker busters in action, as bomb is clearly visible with the only obvious difference from the version seen on Russian media being the color of the tail fins. This is dropped beside a building, and the delay seems to be more than a second after it hits the ground. When it goes off, the underground blast is enough to collapse one side of the building. This is miniature version of the earthquake bomb concept developed by British engineer Barnes Wallis in WWII and successfully used to destroy viaducts and other structures.