The Wooden Armored Vehicles of Marawi

A V-150 fitted with wooden armor. Photo courtesy of Raffy Tima's official Twitter account.

Perhaps the most memorable and most talked about images of the Battle of Marawi (2017) are the armored vehicles of the Armed Forces of the Philippines (AFP) covered with makeshift wooden boards that had been hammered together and fitted on the vehicle's exterior.

Pictures of these started first coming out last June 7, 2017,¹ two weeks into the battle and created quite a stir in the internet, ending up being featured in articles in quite a number of established local and foreign publications like Popular Mechanics,² for example.

It was also a hot topic in Social Media and Forums, and while most have been positive or sympathetic towards it, others tend to be more amused, while others still were downright hostile, ending up making fun of the whole thing. One Chinese webpage reported that some had called the vehicles as “Wooden Chariots”, and even mocked that the wood made the vehicles “amphibious” since wood floats on water.³

’Vehicle Losses’
The main reason why our forces started putting these wooden boards on their vehicles is because the terrorist Dawlah Islamiyah Ranao (DIR) in Marawi had started using RPG-2 Anti-Tank Weapons in much greater quantities than we have ever faced before, and they have proven to be quite effective at breaching our vehicle's armor.⁴

Thus the troops wanted to put more protection on their vehicles in the hopes of making them more survivable in battle. The AFP has not published any official tally on exactly how many vehicles it had lost to these RPGs, but reading around on available news reports, I count at least four vehicles that were lost, with the actual number likely even higher.

Among the first to have been lost were two vehicles which were trapped and then disabled in Marawi. Their pictures were later used as propaganda by the DIR when they posted them online last May 31, 2017.⁵

Another vehicle was lost a couple of days later, with the whole incident caught on video and again later used as propaganda by the DIR. The video showed a terrorist holding an RPG launcher and aiming it at what looked like a V-150 Armored Personnel Carrier (APC). The vehicle was later seen billowing in smoke.⁶

A fourth one was lost after it crossed a Bridge, with the enemy firing their RPGs from the third floor of a building. As per the account of one of the soldiers who was inside the vehicle, he saw one RPG round miss and hit the ground in front of the vehicle. The next one though hit straight on, injuring the occupants and burning the vehicle.⁷

’Spaced Armor’
I initially was skeptical about the effectiveness of this type of armor, but our soldiers have testified that they have seen these work in terms of stopping RPG rounds by having them explode on the wood rather than on the actual metal surface of the vehicles.⁸

Now I think what these wood are supposed to accomplish is similar to the concept of “Spaced Armor” where at least two sets of armor are used in combination, set at some distance from each other, with one armor used to degrade the performance of the weapon before it hits the next armor.

’Spaced Armor Study’
In 2014 a definitive study of the use of Spaced Armor against High Explosive Anti Tank (HEAT) (also known as a “Shaped Charge”) rounds was done in China,⁹ and the results showed that Spaced Armor does work, but only under certain specific conditions.

Using actual experimentation and then computer simulation based on that experimentation, Spaced Armor was found to be able to degrade the penetration of a Shaped Charge rounds by as much as 80%, from a calculated penetration of 98 mm to an actual penetration of only 20 mm. But this was done using two steel plates, each 30 mm thick and 140 mm apart from each other.

To replicate the two plates using wood, then it would have to be a lot thicker since wood is around 25 times softer than steel if we compare their Brinell Hardness Number (BHN).¹⁰ So the wood will have to be around 1,500 mm or five feet thick to have the same effect which, of course, makes it highly improbable and impractical.

’HE Rounds’
So our soldiers say the wood works, but the science says it shouldn’t … what’s happening here, then? I think what’s really happening is that first, the armor on our vehicles are just too thin that you don’t actually need a Shaped Charge round to puncture it, a High Explosive (HE) round would be enough shatter it.

The armor on our V-150s for example are only rated to defeat up to 7.62 mm caliber rounds and are actually only 6 mm (0.25 inches) thick.¹¹ Anything more than a 7.62 mm round like any RPG round would be able to defeat it.

Remember that an improvised HE round made from 60 mm mortar rounds I estimated to have around 340 g of explosive filler, more than ten times that on the explosive found on a 40 x 46 mm caliber HE round used on our M203 and M320 Grenade Launchers.

However, an HE round explodes omni-directionally (i.e., in all directions), so if they explode off a wood on top of an armor, then the wood breaking apart absorbs some of the energy of the explosion and at the same time helps redirect the blast outwards since it is the path of least resistance.

’HEAT Rounds’
But the terrorists are known to be using Shaped Charge rounds also which focuses its explosion in one direction and in a much smaller area to defeat armor. A PG-2 HEAT Ammunition used by RPG-2s are designed to be able penetrate up to 200 mm (4 in.) of Rolled Homogenous Armor (RHA),¹² or more than 33 times the armor thickness of our vehicles.

So in that case, what is happening here again? I think a big factor there could be that since the PG-2 rounds in Marawi are mainly just “homemade” copies, then there are differences in the way they are produced, causing them to perform way below what the technical specifications should be.

Now as to what exactly is wrong with those rounds, I think it is better if I just discuss it much later, perhaps if and when the terrorists have made their RPG-2s obsolete and moved on to better and more powerful weapons. For now I will just say that it might have something to do with the liner and the explosives that were used.

’Proper Add-On Armor’
Those could be the factors why the wooden armor ended up being effective against the RPG-2 that the terrorists are using. Note also that vehicle losses due to the RPGs seem to have tapered off after our troops started putting them on their vehicles.

So as long as the enemy is using homemade RPG-2s, then those wooden armor are fine to use. But, still, ultimately it may be best for our armed forces to invest in a PROPER Anti-RPG Add-on Armor rather than just relying on improvised armor.

For one I think it will mean a big boost to the morale of our soldiers. Right now they are making these improvisations not necessarily because they want to, but more because they think they need to. I think that naturally they would want to have a proper add on armor than the one that they had to make out of their hands themselves.

Also the wood armor does look haphazardly put (which it is), something which goes against the disciplined or ordered mindset of a typical military organization. And they are unsightly and even comical at times, ending up being a magnet for mockery.

Last is that after seeing how the wooden armor have kept their current weapons relatively ineffective, then the terrorists will likely seek to upgrade to better weapons in the future.

’Options and Criteria’
There are many options for Anti-RPG Add-on Armor out there right now, but these are geared mainly against the RPG-7 Anti-Tank Weapon because it is quite prolific and common all throughout the world and thus there is a lot of demand for products to protect against it.

But for our use, we will need one that will work not only against the PG-2 Shaped Charge round copies, but also against the improvised HE rounds of the RPG-2 for now. Traditional anti-RPG-7 countermeasures like Slat (or Cage) Armor works best against Shaped Charge rounds, but I don’t think they work well against HE rounds.

Slat armor works by deforming the Conical Liner of a Shaped Charge round thus preventing a proper explosive jet to be formed, but HE rounds aren’t as dependent on that. I think Composite Steel-Ceramic armor will work well against all RPG-2 rounds though, so the AFP might want to consider those.

Other considerations for me is that such an add-on armor should be as light as possible. Any additional weight to the vehicle will tax the engines more, affecting its durability and also reducing the vehicle’s performance.

The armor also has to be combat proven, or at least well tested and documented that they do work against the threats we are expecting. Last is that it has to be durable enough to withstand years and years of regular use in the field, and has to be as low maintenance as possible.

’Parting Shot’
Like it or not, these wooden armor will be one of the more lasting images of the Battle of Marawi. They were improvised because of the need for added protection due to the vehicle losses incurred by the terrorists’ prolific use of RPG-2 weapons.

Their use elicited various reactions from Social Media, most were positive but there were those who were amused or downright mocking also. However, the soldier’s testimonies and actual results after their use seem to show that they indeed to work, but probably only because the rounds used by the terrorist are improvised and homemade.

The AFP might want to consider using proper add-on armor on our vehicles instead of just relying on improvised ones, and they will need to consider an armor that can defeat these improvised RPG-2 rounds.

Kudos to our soldiers for their spirit of innovation for making these wooden armor despite the lack of budget and and under the intense pressure of combat, and coming up with the Wooden Armored Vehicles of Marawi.

A Simba fitted with wooden armor. Photo courtesy of Jeff Canoy's official Twitter account.

SOURCES:

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1. ISIS Hunter V-150 with Wood Armor,
   (https://web.archive.org/web/20170718024053/https://twitter.com/raffytima/status/872314378925867008) 


2. These ISIS-Fighting Philippine Tanks Are Clad in DIY Wooden "Armor",
   (https://web.archive.org/web/20170617070938/http://www.popularmechanics.com/military/weapons/a26804/wooden-armor-tank-rockets/) 


3. The Philippine military chariot loaded wooden armored combat IS friends joked: firewood return,
   (https://web.archive.org/web/20170718024257/http://www.bestchinanews.com/Military/7316.html) 


4. The RPG-2s of Marawi,
   (https://web.archive.org/web/20170718025602/https://rhk111smilitaryandarmspage.wordpress.com/2017/07/09/the-rpg-2s-of-marawi/) 


5. In pictures: ISIS attacks Philippine Army convoy in Marawi, many armored vehicles captured,
   (https://web.archive.org/web/20170618145244/https://www.almasdarnews.com/article/pictures-isis-attacks-philippine-army-convoy-marawi-many-armored-vehicles-captured/) 


6. First official ISIS video emerges from Marawi, shows heavy clashes with Philippine Army,
   (https://web.archive.org/web/20170714100152/https://www.almasdarnews.com/article/first-official-isis-video-emerges-marawi-shows-heavy-clashes-philippine-army/) 


7. Military learns painful lesson on urban warfare,
   (https://web.archive.org/web/20170707171517/http://www.straitstimes.com/asia/se-asia/military-learns-painful-lesson-on-urban-warfare) 


8. Wood-reinforced vehicles foil Maute antitank weapons,
   (https://web.archive.org/web/20170620194901/http://newsinfo.inquirer.net/907313/wood-reinforced-vehicles-foil-maute-antitank-weapons) 


9. Spaced Armor Effects on Shaped Charge Jet Penetration,
   (https://web.archive.org/web/20170718024922/https://www.researchgate.net/publication/268452665_Spaced_Armor_Effects_on_Shaped_Charge_Jet_Penetration) 


10. Brinell Hardness Test Equation,
    (http://www.engineersedge.com/manufacturing/brinell_hardness_test_equation_13173.htm) 


11. Cadillac Gage Commando M706,
    (https://web.archive.org/web/20170706000111/http://www.tanks-encyclopedia.com/coldwar/US/Cadillac_Gage_Commando_M706.php) 


12. RPG-2 Anti-Tank Rocket Launcher,
    (https://web.archive.org/web/20170622024015/http://www.military-today.com/firearms/rpg_2.htm)