Max wrote:Joat42 wrote:You need to have magazines on a warship and they are usually located in the citadels which are heavily armored (at least if we talk about modern ships, don't know how the Haraldhs are setup).
Using compressed air/gas for propulsion is far more inefficient, expensive and dangerous than using hydrostatic propulsion, and Safeholds engineers has far more experience in hydraulics than pneumatics.
Even today its extremely difficult to built high pressure gas systems that isn't prone to a diverse range of problems where contamination is the top one. Also, finding leaks in pneumatic systems are a nightmare compared to a hydraulic system where you can see the hydraulic fluid leaking.
Another issue with pneumatic systems compared to hydraulics is that pneumatics require a lot of more energy because of the heat-loss during the compression cycle.
If you need a system that can handle high/heavy loads only hydraulics works in this context, since pneumatics require so much larger motors/cylinders to be able to handle same load.
OK. This is a brain storming session and I'm not all that invested in pneumatic systems. The problem was coupling a turbine to the propulsion. Gearage and other direct connection systems ware given a down-check. I remembered that pneumatic systems had been used recently when a problem like that arose. Hydraulic systems were not practical for some reason. Still, you seem to have some ego attachment to that solution. You've thrown up some pretty weak objections...
No ego attachment at all, just an aversion to bad or unnecessarily complex ideas.
Max wrote:Heat loss fro compression:
Scavenge the the heat and use it to pre-heat the water going into the boiler. If this is a direct burn fuel injected turbine, the compressed air is available from a tap into the compression stage.
That is a zero sum game, for that energy loss/scavenge cycle you need to scale the system up to compensate. Also, when the air is expanded to drive something it's going to get very cold, and at sea things tend be humid and you would quickly get ice buildup. So you would probably have to pipe heat to the motors.
Max wrote:Leaks:
This is air, not some exotic gas. The whistle will lead you to the major leaks and soapy water will find the lesser leaks.
I'm not entirely sure you understand at what pressures this system needs to work at to be somewhat efficient. Compared to for example steam (which carries more workable energy) you need higher pressures. Also, the pneumatic lines will need to have quite a large diameter to be usable. Leaks will be interesting to fix...
Max wrote:Explosive potential:
Intermediate between fuel stores and armaments. Comparable to boilers. You don't need propulsion quite as much as you need ammunition, but it is still one of your more valuable assets and worth some effort to protect. One of the benefits of decoupling the engines and the motors is that you can put the more vulnerable pieces in safer places.
Do you realize how big a chunk of volume the capacitors are going eat up to be able to handle propulsion of a ship? Since at current level of technology they can't be welded and they would need to be riveted together. Riveted seams tend to fail spectacularly at high pressures and that volume of air needs to go somewhere (without destroying other things on it's way). That implies we need to add a safety system to went the air in case of failure, since a sudden wave of overpressure inside the ship would have a tendency to (at best case) rupture your ear drums.
Max wrote:Contamination:
Again, air is not an exotic working fluid and it is fairly easy to clean. Hydraulic fluids (even distilled water) are exotic by comparison and would have to be recycled religiously and losses would be hard to make up.
If you get away from turbines, you might get some use of distilled water with steam pressure accumulators as your working fluid in a hydraulic system.
Max
No, air is not very exotic and it may appear to be easy to clean. The problem arises from the water-vapor in air, it's very hard to dry the air to avoid getting condensation in the system. Condensation leads to rust/oxidation which will contaminate the system and ruin seals. And we are not even talking about contamination caused by building it in the first place.
For hydraulics you can use any type of available oil; vegetable oil works just fine, no need to use distilled water.
Some other problems with pneumatic systems, the higher the pressure the higher the friction; friction causes pressure drops, ie. things will get progressively inefficient. The manufacture of pressure valves, relief valves and flow control valves are much more difficult to manufacture for gas than fluid. Also, pneumatics are very non-linear which can causes all sorts of added problems which needs to be dealt with.
The point is, if you are going with a pneumatic system - just use steam from the beginning since it's more efficient. There is no need to make it more complex by adding different methods of converting and distributing energy. And if you have the technology for building a steam turbine you can most likely build the gearing so you get direct propulsion.
