Pictures from Marawi City showing armoured personnel carriers (APCs) clad in improvised wooden reinforcement have been going viral online.
It is thought that the wooden coverings can trigger the explosion of Rocket Propelled Grenades (RPGs) before they make contact with the actual armour beneath.
Lieutenant Colonel Jo-ar Herrera, spokesman for the Joint Task Force Marawi, said they had proven effective.
“It’s a little effective,” he said. “When it hits the wood, it can explode on impact. It’s really just additional protection.”
A January 2016 article in Popular Mechanics revealed the same trick being used to by Iraqi and Syrian forces, who attached spare tyres to their tanks.
A more recent article on the website discussed the effectiveness of the trick.
It read: “RPGs and other infantry anti-tank weapons use so-called high explosive anti-tank (HEAT) technology, also known as shaped charges.
“A cone-shaped cavity is placed against a slab of metal, or tank armour, and an explosive charge is detonated behind it. The cavity channels the force of the explosion through the cone to the tip. This enables a shaped charge warhead to penetrate armour up to seven times the diameter of the charge.
“The result is that a handheld rocket launcher such as the RPG-2 can penetrate more than 180 millimeters of steel armor. This is more than enough to pierce the armor of a V-150 armored car, which is designed to stop bullets with a diameter of 7.62-millimeters or smaller.
“To be effective, wooden armour would have to do one of two things: stand away from the vehicle’s hull, or be plenty thick.”