Wednesday, May 02, 2012

China developing EMALS-type catapults for aircraft carriers

An EMALS catapult test range in the United States
It could still be a long while before Chinese engineers master a technology that the US has been working on since the mid-1980s 

Chinese engineers are reportedly trying to develop an electromagnetic catapult system for China's future aircraft carriers, the People's Liberation Army Daily claimed in a 28 April report. 

General Ma Weiming (馬偉明), a professor at the PLA Naval University of Engineering, is said to have led the efforts to develop the system, which seeks to emulate the development of the Electromagnetic Aircraft Launch System (EMALS) in the United States. 

Compared to existing steam catapult technology, an electromagnetic catapult is seen to offer improved efficiency, increased launch energy, lower through-life costs and improved end-speed control. Additionally, the scalability of the system is better suited for launching unmanned aerial vehicles. 

My article, published today in Jane's Defence Weekly, continues here (subscription required). What follows is background information not included in my JDW article:

General Ma Weiming
Aside from older carriers, like China’s refurbished ex-Varyag, which use ski jumps to launch aircraft, modern nuclear aircraft carriers use steam catapult technology to give naval aircraft the extra boost necessary to launch (push) from their decks. However, steam technology — which usually uses a piping system to collect steam from the ship’s nuclear reactor (heat is transmitted to a secondary loop via a heat exchanger)* — is very stressful on airframes and is maintenance intensive. 

EMALS catapults use a process similar to an electromagnetic rail gun to accelerate (pull) the shuttle that propels an aircraft on the deck, and allows for more gradual acceleration which reduces stress on the airframe. Given the amount of energy required to propel an aircraft from a deck within 3 seconds — enough to power 12,000 homes, according to Defense Industry Daily — carriers using electromagnetic propulsion require generators that can weigh as much as 80,000lbs. 

Provided the technology is developed in time, the US Navy’s CVN-21 Gerald R. Ford-class aircraft carriers, which are in the building stage, will use EMALS on their decks. The UK has also mulled the technology for its Queen Elizabeth-class carriers, in part to accommodate F-35C aircraft. The US-based General Atomics is spearheading the efforts. Among the advantages of EMALS catapults are their higher energy, which allow for launching of heavier naval aircraft on a deck. It is also said that EMALS make it easier to control the sequence of UAV launches.

Test launches using EMALS have already been successful with a variety of aircraft, with further compatibility testing scheduled for this year and reliability tests next year. System integration and certification expected in 2015, the same year the first CVN-21 hull, the USS Gerald R. Ford, is scheduled for commissioning. 

China reportedly has plans to build two conventional and two nuclear aircraft carriers by 2020. Unconfirmed reports also indicate that the conventionally powered ex-Varyag, which is expected to enter service in August, could eventually be retrofitted as a nuclear-powered carrier and outfitted with EMALS catapults.

*With thanks to James Holmes of the US Naval War College for explaining the principle behind this.


Michael Fagan said...

"The UK has also mulled the technology for its Queen Elizabeth-class carriers, in part to accommodate F-35B aircraft."

You mean the F-35C; the Bravo is the short take-off, vertical landing variant.

There is controversy in Britain because iDave (the Prime Minister) has reversed his previous decision to go with the C variant rather than the B. With the more expensive B, the QE carriers won't need (and therefore won't have) cats-and-traps, and for that reason won't be able to accomodate Rafaeles and Super Hornets - either as guest planes, or as cheaper alternatives to the F-35. Guess who has lobbied against the F-35C? BAE Systems - which also makes the crappy Tornados and the Typhoon.

Michael Fagan said...


"EMALS catapults use a process similar to an electromagnetic rail gun to accelerate (pull) the shuttle that propels an aircraft on the deck..."

The obvious inference to make about a possible Chinese EMALS, is that they are running a parallel railgun program too because, as implied above, the two systems are quite similar in engineering (although the cooling requirements for a railgun will likely be more difficult than for the cats). And there have been rumours that in fact the PLA is running an experimental railgun program - which makes perfect sense to me as an anti-ship, access-denial weapon. Assuming they have the spare cash, the PLA would be stupid to not be spending it on developing a railgun program.

I know - I must stop with my railgun "fixe idee".

J. Michael Cole 寇謐將 said...

Yes, F-35C for carrier-launched, British Navy is also acquiring F-35B VSTOL, though. Thanks for the catch.

There are indeed parallels between EMALS and a railgun, which is something to look out for on the Chinese side. And somehow I know the reference to this system — your "idee fixe" as you put it — would prompt a comment :)

Michael Fagan said...

"Yes, F-35C for carrier-launched, British Navy is also acquiring F-35B VSTOL, though..."

Also? I thought the buy was going to be either/or, as in either the C or the B. The procurement decision has swung back and forth between the two in recent months (because iDave is easily swayed and is reportedly "frightened of people who have stronger views than him"), but I doubt the British can afford to buy both jets (what they should do is kit out the QEs with cats-and-traps and then buy Rafales from the French instead).

The thing with the railgun is that the technology can be stolen to speed up development - unlike the more publicized developments like the aircraft carrier. Learning how to land J-15s (or whatever jet they end up using) on the Varyag at sea is a problem for which there are no real short-cuts; it's pure skill, and it has to be acquired the hard way.

J. Michael Cole 寇謐將 said...

They seem to be going back and forth on the B or C variants. UK DefSec Hammond has recommended UK switch back to B STOVL. Who knows what's going to happen in the end!

Apollo Yeh said...

The last I read about the QEs is that the Queen Elizabeth itself would keep a STOVL configuration and that the Prince of Wales would get built with a CATOBAR configuration. I have this pet theory that this apparent back and forth is the result of my own country's apparent inability to get the F-35's multiple incarnations fielded in a predictable timeframe.