During the early days of World War I, it was not unheard of for airplanes to drop mortar rounds on the enemy. In fact, that was pretty much all those early air warriors had as an ordnance option.
But dropping mortar rounds was soon superseded by dedicated bombers that held racks of dumb bombs that weighed as much as 2,000 pounds.
A German pilot prepares to drop a mortar round on a target. This was what passed for bombing in the early days of World War I. (Youtube screenshot)
Now air-dropped mortar rounds are making a comeback, and they promise to be much more effective. That's because a new generation of extended-range GPS-guided 81mm and 120mm mortar rounds will be leveraged for use from UAVs. These rounds deploy winglets that allow them to glide towards a target as opposed to being committed to a ballistic arc.
As such, they can not only strike within six feet of their aim point thanks to their precision guidance (an optional low-cost laser seeker will give the rounds the ability to engage a moving target), they can also travel over 12 miles when fired from a baseline mortar like the M120 120mm mortar or the M252 81mm mortar.
Now, imagine if these were dropped from a UAV from, say, 25,000 feet, as opposed to being fired by a mortar on the ground. During a presentation at the 2017 Armament System Forum in Fredericksburg, Virginia, hosted by the National Defense Industrial Association, Alan Perkins of UTC Aerospace Systems discussed how these mortars could be used on UAVs like the MQ-1 Predator and the MQ-9 Reaper instead of the usual AGM-114 Hellfire missile.
Commandant of the Marine Corps, Gen. Robert Neller, is briefed on the Advanced Capability Extended Range Mortar (ACERM) during an Office of Naval Research (ONR) awareness day. The ACERM uses dual-mode guidance, advanced aerodynamics and improved propellants to increase the performance significantly beyond that of current systems. (U.S. Navy photo by John F. Williams)
The reason: The mortar rounds will have long range – in excess of 30 miles – when dropped from a UAV's normal altitude. Furthermore their warheads are much smaller than the Hellfire's. The 120mm mortar's M57 round has about four and a half pounds of high explosive. Compare that to the 20-pound warhead on a Hellfire. That greatly reduces collateral damage, but when a 120mm mortar round lands six feet away from some ISIS terrorists, it still ruins their day.
In short, the old way of hitting ground targets for airplanes has become new again.