Railguns — latest update

It’s generally held by USN for sure, and the rest larger navies will follow

so I’m assuming from the technical nature of this discussion that a frigate would lack power and room to house this system in its current form?

Is it generally held that the Rail Gun is the future of naval artillery?

The generator set on the Type 45 produces 47MW the electric propulsion is rated at 40MW so in theory that leaves 7MW. The system is all AC and rated at 4.16kV the frequencies, voltages and load are controlled by computers to a high quality. The voltage is stepped down for the ships services to 440V and 115V. I know little about rail guns but if any existing ships are suited to one then I would expect it would be the Type 45 considering that it has a very advanced IEP.

Indeed, the Integrated Electrical Propulsion (IEP) system on the 45 is the reason I also mentioned it.

The type 45 got 2 very advanced WR-21 gas turbines which according to Wikipedia generates 41.5 MW each, however according to RR it can go higher: http://www.rolls-royce.com/marine/products/diesels_gas_turbines/gas_turbines/wr21.jsp

The WR-21 is the first production aero-derivative gas turbine to incorporate compressor inter-cooling and exhaust heat recuperation technologies that deliver low specific fuel consumption across the engines entire operating range. The 25MW WR-21 has a footprint is no larger than current simple cycle marine gas turbines and offers a 25-27 per cent fuel saving.

In addition it has 2 Diesel generators at 2 mW each so a total of 47MW as mentioned above.

Update on railguns, from Ares:

Video here:

http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=27ec4a53-dcc8-42d0-bd3a-01329aef79a7&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3a70e483c0-a0d0-462d-aaf9-83eb5f3ad9e8&plckScript=blogScript&plckElementId=blogDest

http://www.livescience.com/18714-navy-railgun-tests-leading-ship-superweapon-2020.html

So, what do people think? 10 shots a minute and 50-100 nm.

Could any European ships be adapted to such a railgun? Perhaps the type 45, they are already completely electrified, AFAIK?

Looks like the technology has evolved by leaps and bounds in the last few years. Last I heard of this concept(in reference to the DDX) I read it required so much power than it could only fire 10 shots… a day.:eek:

An Arleigh Burke class destroyer or a Type 45 destroyer with 4 turbines produce excess of 80,000 KW of power, but I am not sure what fraction of it is available as Electric power and how much is used for propulsion.

To provide 33 megajoules of energy per shot and with that firing rate (10 shots per minute, although I don’t expect all shots to be fired at max power) would require 5500 KW of power(at least). So either all the non vital systems would be put on standby ( in which case the system will still struggle to provide that much power) or the generators would have to be upgraded (which means additional load on the turbines, or maybe entirely new propulsion system ?). I think a retrofit would be a very difficult task unless the ship was designed with ample amount of extra on board power.

There would be a similar problem in using a compensated pulse alternator which needs mechanical power via a prime mover (either an electric motor or its own independent gas turbine) to prime up a very heavy flywheel. Although this system might by more compartmentalized, it wouldn’t take anything less than a small retrofit for this as well. I may be wrong but I don’t see any ship, not designed keeping rail gun system in mind, operating rail guns via a retrofit.

The generator set on the Type 45 produces 47MW the electric propulsion is rated at 40MW so in theory that leaves 7MW. The system is all AC and rated at 4.16kV the frequencies, voltages and load are controlled by computers to a high quality. The voltage is stepped down for the ships services to 440V and 115V. I know little about rail guns but if any existing ships are suited to one then I would expect it would be the Type 45 considering that it has a very advanced IEP.

so is it the same priciple as a linear motor except that the projectile is used instead of the guide rail

Why ia it called a rail gun At first I thought it was a gun on the railway like we had in the 2 Worls Wars

Because the projectile connects two conducting rails, completing a current loop under an intense magnetic field, which propels it forward.

Why ia it called a rail gun At first I thought it was a gun on the railway like we had in the 2 Worls Wars

But they need to charge the capacitors, so I would assume they would need a large electrical power source in addition to the space to fit the system?

If you want to fire 10 shots a minute then I would guess you need to charge pretty fast which could imply a large electrical source. That’s why I suggested the type 45.

Any electrical engineers who could comment on this?

An Arleigh Burke class destroyer with 4 turbines produce excess of 80,000 KW of power, but I am not sure what fraction of it is available as Electric power and how much is used for propulsion.

To provide 33 megajoules of energy per shot and with that firing rate (10 shots per minute, although I don’t expect all shots to be fired at max power) would require 5500 KW of power(at least). So either all the non vital systems would be put on standby ( in which case the system will still struggle to provide that much power) or the generators would have to be upgraded (which means additional load on the turbines, or maybe entirely new propulsion system ?). I think a retrofit would be a very difficult task unless the ship was designed with ample amount of extra on board power.

There would be a similar problem in using a compensated pulse alternator which needs mechanical power via a prime mover (either an electric motor or its own independent gas turbine) to prime up a very heavy flywheel. Although this system might by more compartmentalized, it wouldn’t take anything less than a small retrofit for this as well. I may be wrong but I don’t see any ship, not designed keeping rail gun system in mind, operating rail guns via a retrofit.

That’s right, in a nutshell. Coilguns, railguns, and some more obscure electrical weapons use pulses of very high voltage and/or current, thus you need to use capacitors. Capacitor needs to be charged over a resistor because typical internal resistance of source, capacitor and wiring is very low and too much current would be drawn into the capacitor. Time to charge a capacitor equals capacitance multiplied by overall resistance.

Railguns have a major problem with structural damage on rails during the operation. A lot of kinetic energy stresses the rails, plus you have ionization which can result in arc welding. Air brakedown occurs at 3.2kV/mm at standard atmosphere.

Energy bank charge time isn’t that much of an issue if you have top-grade capacitors and big power supply (like ship’s powerplant). If your supply can hold lots of amps then you lower down the charge circuit resistance and time goes down proportionally, not to mention that you’ll have less local resistor losses in form of thermal dissipation. However, cooling down and cleanup of the whole thing is a major issue, and that’s why even cutting-edge system needs several seconds between launches.

Depends on the energy source they are using. If they are using capacitor banks, then a retrofit should be easier, due to greater flexibility of an all electrical system. If the power source is a compensated pulse generator then it is going to be tricky, because unlike capacitor banks, they require massive reinforcements, cannot be deployed in a distributed layout and should be more maintenance intensive due to larger number of moving parts.

But they need to charge the capacitors, so I would assume they would need a large electrical power source in addition to the space to fit the system?

If you want to fire 10 shots a minute then I would guess you need to charge pretty fast which could imply a large electrical source. That’s why I suggested the type 45.

Any electrical engineers who could comment on this?

Could any European ships be adapted to such a railgun? Perhaps the type 45, they are already completely electrified, AFAIK?

Depends on the energy source they are using. If they are using capacitor banks, then a retrofit should be easier, due to greater flexibility of an all electrical system. If the power source is a compensated pulse generator then it is going to be tricky, because unlike capacitor banks, they require massive reinforcements, cannot be deployed in a distributed layout and should be more maintenance intensive due to larger number of moving parts.

ooh can anyone afford not to have it? is it too big for the Type 26 (me no navy expert but i did wonder when it was due to be fielded operationally.

and i also wondered if there are restrictions over technology transfer given that its a US project. Just because its BAE doesn’t mean the UK has access does it?