Mystics & Statistics

This is a new blog post from TDI associate Chip Sayers, who has able to make the Third HAAC in person this time:

Project SKYSWEEPER

Armed First-Person Point of View (FPV) drone use in war zones has become a major topic of discussion in the last number of months and news this week of multiple breaches of security at U.S. military bases in the homeland have brought home the point that we need a general strategy for use against drones anywhere, but that also works in U.S. airspace.  In a war zone, a solution could be relatively straight-forward in that use of “lethal force” on the battlefield is expected.  That doesn’t hold true for use in U.S. airspace.

While this photo is almost certainly for propaganda purposes — it beggars’ belief that such small drones could lift off while burdened so outrageously — this photo does generally illustrate the armed FPV drone concept.

This FPV quadcopter sports twin M-72 -class light anti-tank weapons fixed to fire straight down on unsuspecting armored vehicles. 

The title of this post is an homage to the scale model I built as a 9-year-old of a US Army M-51 “Skysweeper” 75mm automatic antiaircraft gun. The Skysweeper had revolver magazines giving it a rate of fire of 45 rounds per minute, and an on-mount gun-laying radar and fire-control computer that ensured its proximity-fused shells would be placed with deadly accuracy. A similar system could put paid to the drone threat in areas where firing artillery is acceptable. 

In the 1990s, Oerlikon created Advanced Hit Efficiency And Destruction (AHEAD) ammunition for its line of 35mm antiaircraft guns. AHEAD, when fired, passes through three coils on the end of the gun’s barrel.  The first two measure the muzzle velocity of the round and compares that to the measured range of the target from its fire-control computer. The third sets the shell’s fuse to burst at the optimal point to damage the target. AHEAD rounds carry a payload, depending on the shell, of between 152 and 860 tungsten projectiles that can effectively shred anything in its path.

This proof plate from an AHEAD round detonation should be terrifying to anyone on the receiving end of its wrath, especially low-flying aircraft — manned, or unmanned.

A Gepard Flakpanzer. The 35mm AAA system is self-contained with search and target tracking radars, fire-control computer and guns on a turret with a Leopard tank chassis.  Note the coils at the ends of the gun barrels for programming AHEAD rounds.

The German Gepard 35mm Self-Propelled Anti-Aircraft Gun (SPAAG) has been sent to Ukraine and, according to reports, the Gepard has proven to be highly effective against Russian drones. NATO countries have managed to scrape together 52 Gepards to cover potentially 1,100 kilometers of frontage, leaving an average density of one Gepard for every 20 kilometers in a simplistic, but illustrative calculation. Ammunition has also been a problem because Switzerland — the country of origin — objected to “violating their neutral status” by selling it to combatants. It begs the question of what they thought their weapons and ammunition were going to be used for — Fourth of July celebrations?  NATO has obtained through hook and by crook a quarter-million rounds, but that’s less than 4.4 minutes of fire, across the force. 

However, AAA is of no use against drones operating in U.S. airspace.  This brings to mind “the Battle of Palmdale” when a Navy drone went rogue and overflew Los Angeles in August 1956. Air Defense Command interceptors attempted multiple times to down the drone with unguided rockets, only to have the rockets’ high-explosive warheads wreak havoc on the ground below.

As we saw in last year’s shootdown of a Chinese balloon which crossed the entire breadth of the Continental U.S. (or CONUS), once the aircraft enters U.S. airspace, we must be concerned with wreckage crashing on the good citizens of Muleshoe, TX or other sparsely populated points of the country. Gone are the days when USAF Air Defense Command envisioned using rockets with nuclear warheads in U.S. airspace to defend against Soviet bombers with much larger nuclear payloads aboard. In last year’s incident, once the decision was made to finally bring down the Chinese balloon, USAF interceptors were held back until the balloon had cleared the U.S. coast, but not so far as to cause the wreckage to land in deep water.  While the high-altitude interception went off like clockwork (believe me, it was not as easy as it looked) we obviously need a means of dealing with threats that don’t risk causing physical harm to bystanders.

In Southeast Asia, reconnaissance drones were used in large numbers to photograph denied areas of North Vietnam.  Usually, they were launched from DC-130 motherships, flew over their North Vietnamese objectives, and were recovered over the South China Sea by waiting CH-3 helicopters that snared the drones’ recovery parachutes, lest they be damaged on landing. The system proved incredibly reliable with one source claiming that in 2,700+ attempts, over 2,600 were successful — a remarkable recovery rate.

A USAF C-119J demonstrates the parachute recovery technique.

USAF CH-3 helicopter with a Ryan AQM-34R Lightning Bug reconnaissance drone in tow.

The sad end of a happy warrior (he’s seemingly smiling). The North Vietnamese took the drone threat seriously and VPAF interceptor pilots were given full victory credit for shooting down a drone.

In a similar manner, helicopters or small cargo planes could use capture nets to sweep up drones fairly cheaply. Obviously, this would require a fairly permissive air defense environment, such as that found in U.S. airspace, Israel and parts of Ukraine. It is a simple, but likely effective technique when used appropriately. The most difficult part of this scheme is having the helicopter (or cargo plane) on station when drones are in the air.  Aircraft could be put up preemptively when the likelihood of drone incursions is high and aircraft available for other missions — such as aircrew recovery — could be ready as quickly as attaching the catch apparatus to an external cargo hook. In Israel’s current situation, one could envision a lot of helicopters and other aircraft being very busy, indeed. However, by using aircraft already on hand, there would be little sunk cost other than aircrew training.

Another approach would be to jam the drone’s control signal. This, of course, would not work on drones that have an autonomous guidance system similar to the U.S. Lightning Bugs flying over North Vietnam, though that carries its own set of issues. Rather infamously, the Lightning Bug that was to provide the final reconnaissance for the raid to free prisoners from the North Vietnamese POW camp at Son Tay in 1970 went astray because the drone turned to soon and didn’t see that the camp had been flooded by monsoon rains and evacuated. In any event, jamming drones in the CONUS could potentially interfere with civilian bandwidths, causing the same kind of complaints that caused sonic booms to be banned over the U.S. mainland. Nevertheless, relatively low-powered jammers that could be located in the center of a large military installation might still be useful.

High-power microwave generators can be highly directional and could interfere with a drones electronics to the point that its circuit boards are “fried,” knocking the aircraft out of the sky. While purpose-built HPM weapons may appear on the battlefield in the very near future, the primary radar of the Lockheed F-35 Lightning II is believed to be capable of performing such duties and are becoming operational at such rates that they could be tasked for this under certain circumstances.

Air defense lasers may be an ideal weapon for dealing with drones, but they have been long promised and thus far failed to achieve operational status. Whatever their issues, particle beam weapons are probably further out on the technology horizon than lasers.  In the meantime, laser “dazzlers,” designed to temporarily blind pilots, have been out there — and effective — since the Falklands War, 42 years ago. Laser dazzlers could at least keep the drones from getting good optical reconnaissance data and deter amateurs from overflying facilities that may easily ruin their drone’s optics (whether or not they really can).

While we wait for these perfect weapons, rather more primitive arms may just fill the bill: just prior to WWII, the British developed an antiaircraft weapon the consisted of a multiple rocket launcher where the rockets trailed cables to ensnare German Stukas trying to bomb Royal Navy capital ships at sea. A similar system might be effective against drones that would be brought down by hitting or being hit by the streaming cable. Better still would be if they could successfully boost a net into the air. This approach would be particularly attractive as the threat drones are generally relatively slow and are unlikely to see such an attack unless it is launched from directly in the drone’s flight path. It would also be a relatively low threat for accompanying infantry. Such a “monkey catcher” could be mounted in pairs on an armored vehicle’s turret. On the platoon or company command net, the order “drone left,” “drone forward,” or “drone right,” the unit’s vehicles could slew their turrets to face the threat and each fire a net in that direction. An individual monkey catcher might not have a high probability of success, but multiples firing from different angles would have a much higher chance of knocking down the offending drone.

At some point, laser air defense weapons will mature and be fielded, ending the current threat. Until that time, “out-of-the-box” thinking may provide a more near-term solution to the threat we face today.