Boeing and defense company Nammo partnering with the US Army have set a new range record during an indirect fire test of a ramjet-powered artillery shell when a Ramjet 155-mm round was fired from a 58-caliber Extended Range Cannon Artillery (ERCA).
Modern artillery has made many advances, but in terms of range, the guns used by the Western powers haven't improved more than marginally. This is unfortunate because rivals like Russia rely heavily on artillery fire, especially rocket artillery, which has over three times the range of cannon fire.
To overcome this, Boeing and Norway-based Nammo have partnered under the US Army’s XM1155 program to develop a new class of extremely long range artillery that uses advanced ramjet technology, yet can be fired by standard guns without modification.
The 155-mm shell used in the recent record-setting test at the Army's Yuma Proving Ground in Arizona and earlier tests using a 39-caliber towed artillery cannon at the Andøya Test Center in Norway looks very similar to a conventional round, but that is only superficial.
Where the fuse goes on a conventional shell, the Boeing/Nammo shell has an air intake with an aerospike projecting from it. Inside, the body of the shell is lined with solid rocket fuel that takes up little space because there's no oxidizer in the mix. When the shell is fired, it quickly accelerates to supersonic speeds, where the ramjet kicks in. The air in front of the shell is scooped in, compressed, mixed with the fuel, and burns, generating thrust.
The upshot of this is that the 155-mm shell increases the range from about 14 miles (22 km) to 93 miles (150 km). The Yuma test's exact record distance has not been released, but this gives some idea of what the goal was.
According to Boeing, the purpose of the test was to prove that the new ramjet shell could be safely fired from the ERCA gun and to demonstrate its performance in flight. The next objective will be to concentrate on the precision of the round.
"This program now has a thoroughly tested propulsion system that guarantees enormous range increases for all artillery cannons," said Morten Brandtzæg, Nammo CEO. "We believe the major development hurdles have now been cleared and production is viable within a relatively short time frame.
"Our successful tests demonstrate that ramjet projectiles – a real collaborative achievement of Boeing and Nammo – offer the range and precision desired by the Army. Ramjet technology heralds a revolution in artillery, significantly extending range and delivering strategic advantages to our users."
The video below discusses the Ramjet shell.
Source: Boeing