General Atomics Electromagnetic Rail Gun

[bobbymike]

From Defensetech.org -

http://defensetech.org/2010/05/05/killer-drone-builder-general-atomics-builds-killer-electromagnetic-rail-cannon/

[donnage99]

I thought BAE is the one working on this?

[bobbymike]

donnage99 - Ya I had not heard of any program like this at G.A. until this story. I have BAE as well as the Naval Research Laboratory - Future Weapons had a segment on the NRL's rail gun, I believe the one that holds the record for energy at 9 Mjs.

[TomS]

It's not a huge shock to see G.A. working on this, though. They are the lead on the Navy's electromagnetic launch system (catapult) effort, so they have plenty of expertise on pulsed power applications.  EMALS is more of a linear motor/coil gun, but some of the support technologies are certainly transferable.

Here's the page for GA's Advanced Weapon Launcher system program.
http://atg.ga.com/EM/defense/railgun/index.php

[DSE]

It's not a huge shock to see G.A. working on this, though. They are the lead on the Navy's electromagnetic launch system (catapult) effort, so they have plenty of expertise on pulsed power applications.  EMALS is more of a linear motor/coil gun, but some of the support technologies are certainly transferable.

Here's the page for GA's Advanced Weapon Launcher system program.
http://atg.ga.com/EM/defense/railgun/index.php

Though EMALS isn't exactly an over performing project.

[bobbymike]

Speaking of which from Insidedefense.com - PM: Catapult Mishap Delays First EMALS Aircraft Launch Until Fall

DefenseAlert, May 4, 2010 -- The first test launch of an aircraft using the Electromagnetic Aircraft Launch System has been delayed until the fall, due to a catapult failure earlier this year, the program manager said yesterday.

[ouroboros]

I wouldn't call the EMALS problem an outright failure. From the descriptions, it sounds like a combination of someone flipping a bit in the software and setting it to reverse rather than forward during the test, and the not so hot idea of putting critical equipment directly in the path of the shuttle should it reverse (or overshoot if returning from the other end under normal operations). The first is an easy software fix, the second is a layout issue that may not be surmountable depending on the shape of the equipment spaces on the new CVN though.

The interesting thing about EMALS is the possibility of having a nonlinear shape to the launch track, and thus the possibility of fitting catapults to skijump carriers.

Has there been anything conceptually similar for railguns? I seem to remember a bizarre concept for a coilgun (not a railgun) that used a circular ring first stage to bring the projectile up to speed, and a shorter main barrel for final boost. This allowed a surprising compact design, though considering the nature of where I saw it, I wouldn't be surprised if that was pure fantasy and not grounded in reality. Though the similarity with launch loop mechanical launchers, and the fact that the loop helps solve the railgun projectile/sabot injection issues is the reason why the concept may have legs.

[bobbymike]

There is coilgun work being done I think by the Army Research Lab. I saw something on Future Weapons about a coilgun mortar.

[bobbymike]

EMALS News from Aviation Week

Recent tests at NAS Lakehurst, N.J., should have builders of the USS Gerald R. Ford (CVN-78) sleeping more easily. The Navy’s risky bet in the design of the Ford—its reliance on an all-electric replacement for the steam catapult—appears to be paying off.

Problems and delays with the electromagnetic aircraft launch system (Emals) last year were a threat to the carrier, because its design and construction reached a point where reverting to steam would have been difficult and expensive. With Emals in mind, the Ford-class features a much more powerful electrical generation and distribution system than the predecessor Nimitz-class ships, along with the virtual elimination of steam-energized services such as heating, galleys and pumps and 10 km. (6 mi.) of steam lines.

The Navy has delayed delivery of the $11.5-billion carrier for budgetary reasons twice. (Commissioning is expected in September 2015.) The scheduled progress of Emals now matches the carrier’s build schedule but with so little slack in some areas that the Navy is continuing to monitor development of the system closely.

The land-based prototype of Emals at Lakehurst started high-speed “no load” test runs in April, and will start to accelerate with dead loads—ballast—at speeds increasing from 50-180 kt. At prime contractor General Atomics’ plant in Tupelo, Miss., prototypes of the Kato Engineering power modules are undergoing accelerated life testing, performing 6,800 power cycles. So far, tests show no signs that the powerful electrical surges cause electromagnetic interference with aircraft, ammunition or ejection seats. The first aircraft launch at Lakehurst is expected by year-end.

Initial Emals components for Ford are due at the Newport News shipyard in May 2011. The tightest schedule concerns the 12 power units, which are high-speed motor-generators weighing 80,000 lb. each and functioning as flywheel energy storage and release units. Some are not due at the yard until the day before they are installed.

Emals will deliver energy more flexibly than Nimitz-class steam catapults. The F-35C Joint Strike Fighter demands more launch energy than the F/A-18E/F, and Emals will allow the Ford to launch the JSF at maximum weight with less wind-over-deck.

Emals can also be set to lower energy levels than a steam catapult, allowing it to launch small, lightly loaded aircraft like unmanned aerial vehicles.

The Ford class features a new advanced arrester gear as well, also produced by General Atomics and replacing hydraulic rams with a water turbine and induction motor, permitting a finer setting of arresting force and reducing the need for manual adjustments between landings. Like Emals, it is expected to allow the carrier to operate heavier and lighter aircraft than the current Mk. 7 arrester gear. Unlike Emals, it is intended to be backfitted to Nimitz-class carriers.

The carrier will be part of the process of introducing a landing guidance system to the Navy: the Joint Precision Approach and Landing System (Jpals). It will be one of the first ships with Jpals, which is slated to be on all carriers and large amphibious transports by 2018. The second Ford-class ship, CVN-79, is due to be the first carrier without SPN-41 and SPN-46 radars, which provide carriers with an automatic landing capability.

Adoption of Jpals is urgent for the Navy because current radars will not be supportable after the early 2020s. Jpals is also associated with the F-35C, because the fighter’s reduced radar cross-section means that current radar-based autolanding systems cannot acquire it. The installation of Jpals on carriers will match service entry of the F-35C.

The first increment of Jpals will be qualified for flight guidance down to 200 ft. and 0.5-mi. visibility. Accuracy is intended to be sufficient for an automatic landing, and that capability is being demonstrated as part of the Northrop Grumman X-47B Navy Unmanned Combat Air System program.

The key to its accuracy is shipboard-relative GPS, which uses two GPS receivers—one forward of the island on the starboard side and the other on the portside stern. The space between the sensors and their relative location allows the system to measure the position of the ship accurately and track its movement—speed, pitch, roll and heave—with the aid of three Northrop Grumman LN-270 inertial reference units. Using the same differential GPS technique, Jpals also provides an accurate aircraft position. A data link allows the system to transmit automatic landing guidance.

Credit: US Navy