Air Weapons: Thermobaric Grenades go Airborne


December 21, 2023: Ukraine has demonstrated lots of ingenuity and innovation while fighting the invading Russian forces. A recent example of this was the Ukrainian use of UAVs (quadcopters) carrying a thermobaric/FAE (Fuel Air Explosive) grenade. The grenade carrying UAVs continuously search for Russian troops and only return to their operator to get their batteries recharged or to have another grenade installed after a successful attack. Using a small UAV armed with an FAE grenade doesn’t kill a lot of Russian soldiers but the existence of these armed UAVs terrifies Russian troops. The quadcopters are small targets and difficult to hit with rifle or machine-gun fire The UAVs are operated by nearby Ukrainian operators who are also taking notes on the dispositions of Russian forces. The UAV operators are difficult to attack because the Russian don’t know where they are.

UAVs have become heavily used by both sides for surveillance, reconnaissance, and attacks. These UAVs have become common in the combat zone because thousands have been built and used by both sides. This has been revealing for military analysts and leaders worldwide. The Russian invasion of Ukraine two years ago has resulted in the first, since World War II, major war between nations armed with nearly equal and similar weapons. What is different is the heavy use of UAVs. This has brought about changes in tactics and, to a lesser extent, strategy. Ukraine developed and heavily uses USV (Unmanned Surface Vehicles) which are used mainly for attacks on enemy naval targets and bases. Because of these USVs as well as UAVs the Russian Black Sea fleet has taken heavy losses and no longer controls the Black Sea. UAVs carrying explosives have attacked ships as well as naval bases. Warships and their bases shoot down UAVs but since these attackers are not manned, the attacker can afford to lose a lot of them in order to damage the Russian ships and naval bases. Before this UAV revolution, the attacker would lose more personnel than the defender. Attacks using UAVs reverse that situation with the defender, no matter how well armed, losing far more people than the attacker. This is one reason for the attack UAVs to carry FAE grenades or larger FAE weapons.

Russia has been using FAE weapons for a long time, especially in Ukraine. Earlier in the Ukraine War Russia sent some of their TOS-1A tank-mounted thermobaric/FAE 220mm rocket launchers to Ukraine. A TOS-1A carries 24 220mm rockets while a separate reload vehicle carries two pods containing rockets.

These weapons are a relatively recent development. Efforts to develop a workable FAE began over a century ago during World War One and continued until becoming effective enough for engineering use by the U.S. military during the Vietnam War. Then it was used primarily to create instant helicopter fields in the jungle. Russia got their thermobaric tech perfected a decade later, with the help of recent American FAE developments. Russia considered FAE devices chemical weapons and saw their TOS-1A vehicles as flamethrowers. Many NATO and Russian-backed nations also obtained or developed some FAE weapons.

FAEs are incredibly destructive because they literally create a fireball. These range in size from a few meters in diameter to over 500 meters. The smallest ones are FAE hand grenades or small projectiles while the larger ones are aircraft-transported bombs. Some short range ballistic missiles also have optional FAE warheads.

Technically, FAE devices can be incredibly destructive, incinerating anyone inside the fireball. Efforts to ban FAEs as inhumane and a crime against humanity have failed. This is largely because FAEs are simply a specialized explosive that is not radioactive and does not generate a lot of metal fragments. FAEs can do things high explosives cannot do. Clearing minefields is one example. Another is destroying an enemy position in a remote area with a lot of underground bunkers and surrounded by minefields. Since September 11, 2001, American forces have regularly used FAEs, some air dropped, to clear minefields. FAEs will detonate the mines and reach deep into caves or bunkers to kill anyone in there. Islamic terrorists have tried, with mixed success, to include improvised FAEs for major attacks.

Russia first used TOS-1 vehicles in Afghanistan during the 1980s. At the time, their TOS rockets only had a range of 3,500 meters and demonstrated sufficient performance in Syria and Iraq to revive sales of some older systems. One of the more unique among these revived weapons is the TOS-1A. The “TOS” stands for “heavy flamethrower system” because the TOS-1A only fires rockets equipped with FAE warheads. The TOS-1A is a 45 ton vehicle that uses a T-72 tank chassis with the turret replaced by a box-like launcher for 24 220mm rockets. These come in two sizes, one is 3.3 meters (20.8 feet) long weighing 173 kg (381 pounds) while the other is 3.7 meters long and weighs 217 kg. The larger rocket has a longer (6,000 meters) range. The TOS-1A is not a direct-fire weapon but the vehicle is meant to get close to the target and is equipped with a laser range finder and computerized fire control system to elevate the launcher to the right angle to put the unguided rocket as close to the target as possible.

While FAE can be very effective, it is a temperamental type of explosive that is not widely used. FAEs detonate and spread a mist of fuel (gasoline type stuff, or a mixture of other chemicals) and then ignite it. This creates a large, impressive looking explosion, as well as a powerful blast (called overpressure). The overpressure is powerful enough to set off landmines, as the pressure created on the ground triggers the pressure sensors on anti-personnel and anti-tank mines.

FAE has always been tricky to use. If the wind is blowing the wrong way, or the humidity isn’t quite right, the explosion is something of a fizzle. Russia developed new designs for FAE weapons that overcome many of these problems. Current FAE designs use compressed gas to form a mist cloud of fuel. A detonator then ignites the cloud and causes a huge explosion. The effect is like a nuclear weapon, for there is enormous pressure and a lot of flames. All the oxygen is also used up. If you aren't crushed or burned, you die from suffocation because of the lack of oxygen. Modern FAE chemicals are better able to seep into wherever air can go before detonating. In a cave, everyone dies. Even armored vehicles are vulnerable because some of the fuel sometimes seeps into the vehicle and starts fires when it explodes. Earlier on, if vehicle engines were running, it could cause firing cylinders to rapidly dissemble the engines.

The original TOS-1 was developed in the 1980s and used in combat in Afghanistan in 1988. Apparently, it was successful, but the Russians were withdrawing, and they took their TOS-1s with them. With the collapse of the Soviet Union in 1991, there was little money to build or further develop the TOS-1. At that time there were only about twenty in service. They were used in Chechnya during the 1990s and that was successful enough to revive development. That led to the TOS-1A in 2002 and production has increased since then. Over two hundred TOS-1s, most of them the 1A model, have been ordered. In Syria, the Assad forces used some of the older TOS-1s in combat while Iraq bought a dozen TOS-1As which they used extensively in the battle for Mosul. For city fighting the TOS-1A is particularly effective as the overpressure can kill or disable enemy troops inside buildings or bunkers as well as set off landmines and disable other types of explosive traps. Algeria bought some 52 TOS-1As and stationed the first ones to arrive on the Libyan border. It is unclear why Algeria purchased TOS-1A vehicles. Azerbaijan also ordered 36 of them and used them against Armenian forces in open areas with some success. Armenia has also purchased some TOS-1A vehicles of its own.

In 2017 the U.S. used one of its large (9.8 ton) MOAB (Massive Ordnance Air Blast) GPS-guided FAE bombs in combat for the first time. The MOAB was dropped on an ISIL (Islamic State in Iraq and the Levant) tunnel and cave complex in eastern Afghanistan. This area was guarded by hundreds of landmines and explosive traps in addition to several hundred of the Islamic terrorists. MOAB was officially known as GBU-43/B, and performed as expected, leaving over a hundred visible dead. Some ISIL men may have been vaporized and others buried deep in the collapsed caves and tunnels. A large explosion like this creates an overpressure that not only kills troops deep inside bunkers, but the shock wave also causes tunnels to collapse.

MOAB entered service in 2003 and fifteen were built but were never used for fear it would kill nearby civilians. The ISIL complex in Afghanistan was known to be restricted to ISIL members and had become a major storage site for weapons, ammo and bomb making components. It was also a training center, especially for bomb builders. Afghan forces were reluctant to try and take it from the ground because they had suffered a lot of casualties just probing the defenses. Smart bombs and laser guided missiles could destroy cave and tunnel entrances but not get at the men and material inside. This was the sort of target MOAB was made for. Within hours of the explosion Afghan troops and American special operations forces advanced through the areas destroyed by overpressure and blast, including minefields, and encountered no resistance. Using robots and various sensors it was found that a lot of items stored in those caves were destroyed or buried. Excavating all that was time-consuming and necessary to recover useful information on ISIL operations.

MOAB is not dropped out of bombers but pushed out the back of a SOCOM (Special Operations Command) MC-130E aircraft, or any similar aircraft with a rear ramp like the C-17. The blast can be felt several kilometers away, and the mushroom shaped cloud, which rises to over 3,000 meters high, can be seen more than 40 kilometers away.

MOAB replaced the Vietnam era BLU-82 (Daisy Cutter) bomb, which used a 6.3 ton slurry of ammonium nitrate and powdered aluminum. MOAB uses more powerful tritonal explosives. In addition to a more powerful explosion, MOAB doesn't need a parachute, like the Daisy Cutter, but uses a GPS (like JDAM) and an aerodynamic body to glide to and detonate the bomb at a precise area. Thus, the MOAB can be dropped from a higher altitude, outside the range of machine-guns and rifles. The force of a MOAB explosion is sufficient to knock over tanks and kill any exposed people within several hundred meters of the detonation.

Not to be outdone in 2005 Russia revealed it had built a bomb similar to MOAB, but theirs contained 7.1 tons of a more powerful explosive than MOAB used, and they claimed that the blast radius of the Russia bomb was twice the size of MOABs. While MOAB is equivalent to 11 tons of TNT, the Russian bomb was said to be equal to 44 tons of TNT. It also appeared, from the Russian test video, that their bomb was a FAE (fuel air explosive). This could be seen from the typical FAE two stage explosion. A Russian video also showed the area surrounding the blast, and the damage was consistent with an FAE explosion, and about as powerful as MOAB. It appears that the Russians were making publicity, not a factual announcement of a new weapon.

Russia also brought TOS-1As to Ukraine where they could use their new rockets with a range of 10 kilometers. The original 3.5 kilometers range rocket had been replaced with a six kilometer range model. Longer range rockets are important for TOS-1A survival. Russia has found that in combat these vehicles and their large load of FAE rockets are vulnerable to enemy fire, especially from ATGMs (anti-tank guided missiles). Some of these have ranges of five to ten kilometers and use “fire and forget” guidance. To protect TOS-1A vehicles from all this, TOS-1As are usually used in the midst of a group of other armored combat vehicles. The longer range rockets make it possible for TOS-1A vehicles to remain behind a hill or buildings for protection while it fires rockets at targets it cannot see. Russian troops provide a degree of fire control and, when firing a barrage of up to 24 rockets, precision is less of a factor. This led to the development of TOS-2, a truck mounted FAE rocket launcher which carried smaller rocket pods containing twelve rockets. TOS-2 is meant to keep out of sight while firing its rockets. Both TOS-2 and TOS-1 vehicles have a crew consisting of a commander, driver and gunner. In Ukraine, the Ukrainians have their own FAE weapons and have become quite proficient at destroying TOS-1A and reloading vehicles with ATGMs and armed UAVs.




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