Infantry: Reusable Grenade Size UAV


August 15, 2021: The U.S. Marines are evaluating the new Drone40 UAV (Unmanned Aerial Vehicle) after noting its successful use by British troops in Mali, where foreign troops serve as part of a peacekeeping and counterterrorism effort. The British found the Drone40 very useful and word got around.

Drone40 looks like a 40mm tube-launched grenade. Grenade40 can be launched from the standard 40mm grenade launcher carried by infantry units. Once launched, or thrown, like a grenade, Drone40 stays in the air by extending four quad-copter type propellers. Using a form of UAV flight most preferred by the infantry, Drone40 can pause and hover to scrutinize areas or objects as well as enter structures, including caves. The hover ability is much more useful in built-up areas where you have to look into windows or alleys. If a Done40 finds a target the troops can either call in an air or artillery strike or, if the enemy is close enough, use their grenade launcher to fire 40mm high-explosive grenades. If the enemy is really close and comes into view, you can open fire using your rifles.

The standard Drone40 weighs 190 grams (6.7 ounces) while the heaviest version weighs 300 grams (10.6 ounces). The heavier versions carry larger and heavier payloads like high-explosive or armor-piercing warheads. Heavier payload versions also carry a laser designator, electronic jammer or a smoke/flash grenade. The heavier models have less endurance but all can remain in action for at least 30 minutes. The non-explosive Drone40s can be recovered and reused after a battery recharge and resetting the quad-copter propellers inside the 40mm shell. Some repairs may be needed depending on where and how the Drone40 came down.

Drone40 was developed by an Australian firm that took note of several earlier 40mm UAVs and concentrated on characteristics that were most popular with the troops. Drone40 built on two decades of earlier efforts to produce a portable recon device for infantry and was facing troops in many countries who liked what they had seen so far, but were ready for something that was better.

Drone40 was put on sale in 2019, and by late 2020 British troops in Mali had received several hundred Done40s and soon reported that they wanted more. The basic Drone40 is the same size as the standard 40mm grenade and thus usable in all infantry 40mm grenade launchers. This Drone40 is equipped to take video or pictures and transmit them back to the operator. A small tablet-like controller is used by the operator who must remain in sight of the Drone40 to control it and receive images at max range (20 kilometers). The image surveillance Drone40 can operate for up to 60 minutes if cruise speed is used. That speed can be nearly doubled to 1.2 kilometers a minute but that uses up more battery life. Drone40s are also capable of operating as a swarm in mass operations with explosive payloads. The success of Drone40 in Mali has generated interest in other countries looking for a portable, relatively inexpensive and reusable 40mm UAV.

The development of systems like Drone40 began shortly after 2001 as American operations in Afghanistan generated demand for improved surveillance tools for the infantry. That led to the 2009 arrival of the Switchblade UAV. Switchblade weighed one kilogram (2.2 pounds) and was a small UAV launched from its tube-shaped shipping container. Switchblade was sent to Afghanistan for secret field testing. This was very successful and the troops demanded more, and more, and more. Switchblade completed development by late 2009 and was initially thought useful only for special operations troops. In 2011, after a year of successful field testing with production models, the army ordered over a hundred Switchblades for troop use and since then has ordered a lot more.

While Switchblade was developed for the army, the marines apparently noted the success that soldiers and SOCOM (Special Operations Command) had with this system and ordered them as well. Switchblade was very popular with troops in Afghanistan and with SOCOM in all sorts of places they won’t discuss in detail. Switchblade is still used and thousands have been ordered and many of them used. There have been several upgrades

Switchblade was a lightweight and expendable (used only once) UAV that could also be equipped with explosives. When Switchblade is launched from its shipping/storage tube, wings flip out, a battery-powered propeller starts spinning and a vidcam begins broadcasting images to the operator. The Switchblade is operated using the same controller as the larger (two kg) Raven UAV. A complete Switchblade system (missile, container, and controller) weighs 5.5 kg (12.1 pounds).

Moving at up to a kilometer a minute, the Switchblade can stay in the air for 20-40 minutes, depending on whether or not it is armed with explosives. Switchblade can operate up to ten kilometers from the operator. The armed version can be flown to a target and detonated, having about the same explosive effect as a hand grenade. Switchblade enables ground troops to get at an enemy taking cover in a hard-to-see location.

Technically a guided missile, the use of Switchblade as a reconnaissance tool encouraged developers to refer to it as a UAV. But because of the warhead option, and its slow speed, Switchblade also functions like a rather small cruise missile. The troops were particularly enthusiastic about the armed version because it allowed them to more quickly take out snipers or a few bad guys in a compound full of civilians.

In 2013 the U.S. Navy requested a version of Switchblade, just for reconnaissance, that could be launched from ships or submerged (at periscope depth) submarines. In this case the sub would have a communications mast on the surface to receive data from what was called the Blackwing. This version is a little heavier, at 1.8 kg (four pounds). The size of the Blackwing is designed to fit into existing navy countermeasure launchers. Blackwing has no warhead option so endurance is about 60 minutes. Blackwing uses encrypted digital communications compatible with current navy systems. When released from a submarine countermeasures launcher, the Blackwing container pops to the surface and the Blackwing is ejected into flight like the other Switchblades. In 2016 the navy ordered over a hundred Blackwings for widespread testing from deployed ships. Based on this, armed versions of Blackwing were developed, even though they had less endurance. Blackwing was declared operational in late 2020 and the navy ordered more, including 120 recon versions for use on submarines. Tests with Blackwing launched from subs proved very useful when the sub had used its passive (silent) sonar to detect a possible target but needed a visual of the ship to determine what kind of target it was. Using Blackwing subs can confirm distant targets and use their Mk 48 torpedoes at max range (about 40-100 kilometers depending on speed). Subs found other uses for Blackwing that were not made public.

Switchblade is not a unique concept, as these “loitering munitions” have been around for decades. What Switchblade provided was a design that met the needs of combat forces, especially special operations personnel. Since Switchblade entered service and its popularity became widely known, similar systems have appeared, trying to provide features that Switchblade lacked but the troops would appreciate.

An earlier example of this was GLAUS (Grenade Launched Unmanned Aerial System). It looks like a 40mm grenade but is longer and heavier than the standard 40mm high-explosive shell and comes in two versions. One version launches a UAV with pop-out plastic wings, propeller and control surfaces. This version contains a video camera and communications link to the handheld controller used by the soldier who fired it. The comm-link is good for 2,000 meters and the UAV can stay in the air for 90 minutes. Each infantry fire team (4-5 troops) has one man designated a grenadier, with an M320 40mm grenade launcher attached under his assault rifle barrel. With the GLAUS UAV in the air, the team or squad (a larger unit with two fire teams) leader can scout the surrounding area from altitudes as high as 600 meters (2,000 feet). GLAUS is still considered in development by the U.S. Army, which has not found a manufacturer for it or interest in buying a lot of them. In part that is because there is a lot of competition. The army did submit a patent application for GLAUS in 2020 but the success of Drone40 may render GLAUS obsolete.

Most small infantry UAVs, like the current 2 kg (5 pound) Raven, which also operates close to the ground, usually at 100- or 200-meters altitude. Ravens are assigned to larger units like platoons (three squads) or companies (3-4 platoons). GLAUS was meant to be small enough for a patrol or small Special Forces team to carry with them and use far from friendly troops.

There was a second version of GLAUS that was a small helicopter, with shorter endurance (about 30 minutes), and the same capabilities as Drone40. GLAUS was not the first guided system built for the 40mm grenade launcher. In 2015 the Pike 40mm grenade was introduced by U.S. defense contractor Raytheon. By 2019 Pike was in production and had its first customer. There was no rush to buy Pike because of the cost. Drone40 costs a few thousand dollars each and is apparently cheaper than Pike plus being reusable.

The existing 40mm high explosive grenade cartridge is about 100mm (4 inches) long and weighs about 545 grams (19 ounces). The 40mm shell which leaves the launcher tube is about 43mm (1.9 inches) long, weighs about 250 grams (nine ounces) and can be fired out to about 400 meters. An experienced grenadier can only fire these grenades accurately at targets as far as 200 meters distant.

The Pike is a longer and heavier 40mm shell. Pike is 430mm (16.8 inches) long and weighs 770 grams (25.6 ounces). While the Pike warhead is about twice as powerful as the unguided 40mm grenade, most of the additional bulk and weight of the Pike is taken up by the laser detector in the nose, a microcomputer, four pop-out fins and electronic and mechanical components to operate the fins to guide the Pike to a target up to 2,000 meters away. The Pike homes in on laser light reflected from the target, which is “painted” by a laser designator that looks like a pistol. Normally Pike is operated by a two-man team. One man is the grenadier, firing the Pike from a common one round 40mm grenade launcher. The second man, the spotter, points the laser designator and holds it on the target until the Pike reaches it (after about 20 seconds). Actually, one person could operate the Pike because at max range Pike will be in flight for about 15 seconds before it can detect the laser light reflected off the target by the handheld laser designator. One person could fire the Pike, then pick up the laser designator, turn it on and designate the target.

Pike will land within five meters of the laser light reflected off the target. The warhead is more powerful than hand grenades so Pike will kill or injure anyone within ten meters (32 feet) of the aim point. Pike obtains its long range by using a small explosive charge to propel Pike about three meters into the air before a smokeless rocket motor takes over giving it the momentum needed to carry it at least 2,000 meters.

As of 2019, only one customer has been found for Pike. The Canadian Army bought some for its special operations troops. The major problem with Pike is the cost of each round. The standard 40mm grenade fired by infantry costs about $30 each. The Pike manufacturer (Raytheon) has not made public the cost of each round but, given the cost of other small laser-guided missiles (like the 70mm APKWS), each Pike probably costs at least $3,000 and probably two or three times that. It could be useful for special operations troops, but for most infantry there are plenty of other guided munitions available, many of them cheaper and more destructive than Pike. Meanwhile, American troops already have a very lightweight UAV with Switchblade, but not as light and portable as Drone40, GLAUS or Pike. The appearance of Drone40 was not surprising because the user demand was there, especially for a reusable version.

Israeli firms also responded to demands for reusability. In 2019 an Israeli firm introduced the Firefly, a loitering UAV, which is portable enough for infantry to carry and continually reuse. There is also the option to replace one of the two batteries with an explosive warhead and turn Firefly into a guided weapon. Another major advantage of Firefly is that it operates like a helicopter, not a fixed-wing aircraft. Being able to hover is a major advantage for loitering munitions used by infantry. What Firefly seems to have done is address all (or most) of the user criticisms of earlier lightweight loitering munition systems.

Firefly was developed by Rafael, the same firm that developed and builds the Spike family of ATGMs (anti-tank guided missiles). Much of the tech in Firefly was based on what is already used in Spike systems. In particular, Firefly has a guidance system that can track and attack a moving target. This can be critical for infantry using such a weapon because these targets are elusive in the first place and, without a UAV, the infantry would not have spotted dangers like snipers or moving troops at all.

Firefly is a dual rotor miniature helicopter and those dual (on top of each other) rotors make it stable in winds that would make a similar-sized fixed-wing or quad-copter UAV unusable. The .4 kg (one pound) warhead replaces the second battery to halve the normal 30 minutes of flight time. The operator uses a small tablet device that is mostly a touch screen and a Firefly controller. Firefly can be controlled up to 500 meters in a built-up (or forested) area or up to 1,500 meters in line-of-sight (nothing between Firefly and operator) mode. Firefly returns to the operator if the control signal is lost. The operator can press an icon on the screen to get Firefly to return immediately, abort an attack or carry out a high speed (19 meters/62 feet a second) attack on a target. The target can be moving, as in a sniper changing firing positions out of sight of the operator. This is accomplished using the ability of the Firefly guidance system to remember the shape of a target and follow it. The Firefly warhead would be most often used against troublesome targets like snipers or hidden machine-guns. Even without the warhead Firefly would be able to locate such lethal adversaries and enable the infantry to avoid them. Firefly can also be launched and operated from a moving vehicle.

The big advantage Firefly had over PIKE, GLAUS and Switchblade is reusability. Carry one Firefly and just use it as a UAV for a dozen or more times. Because of the relative simplicity of the Firefly compared to GLAUS, Pike or Switchblade, it was cheaper. Add in the reusability and Firefly is definitely cheaper. Drone40 and Firefly appear to be dominating the market for small UAVs for infantry use.


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