Discussion Shadow Destroyer Propulsion Design Options

[Urwumpe]

In the final design steps, I noticed that I never really decided how the Shadow Destroyer was meant to be propelled. It was just a waterline model, what happens below the hood was not that interesting. But now, that the ship gets into an add-on, the question became important: How should the ship be propelled?

That is not just a pure engineering question, but also political. It is meant to drive at the same era as the Delta-Glider, so nuclear shouldn't be as feared as it is today, but still, it could face economic and political restrictions.



I have grouped the four leading candidates into this drawing as example:

All versions have a pair of bow thrusters in each float,

Diesel-Electric means the electricity on-board the ship is produced by multiple diesel generator units, and the ship thrust is produced by an electrical engine, in this case housed into two Azipod™ units with two counter-rotating propellers each. That is the current state of the art technology for civilian ships, especially ferries make use of it.

CODLAG or Common Diesel-Electric and Gas Turbine is a combination of the diesel-electric propulsion concept with a gas turbine and electric motors acting on a common propeller joined by a gear box. This is the latest development for military ships.

Nuclear-electric replaces the diesel engines of the diesel-electric approach by two nuclear reactors (there is even room for two more in the hull design). The propulsion is still achieved by Azipod™ units.

Nuclear-direct drive is essentially the state-of-the art for nuclear submarines. each propeller is without gearbox connected to a turbine. Electricity is produced by smaller turbines with directly connected generators. This design offers the highest maximal speed, but also a lot of noise at maximum speed.

Both pod propelled vehicles only have a very high agility even at low speeds, and can even accurately keep station at a location. The classic drive versions rely on rudder and bow thrusters.

In summary:

Option | Fuel | Range | Cruise speed | Max. Speed | Agility | Noise level
Diesel-Electric|Diesel|Low|Low|Medium|High|Very low
CODLAG|Diesel|Low|Low|High|Low|Medium
Nuclear-Electric|Nuclear|Unlimited|Medium|High|High|Low
Nuclear-Direct|Nuclear|Unlimited|Medium|Very high|Low|Medium

Since this is a SWATH, it requires 80% more power for high speeds as a catamaran, so don't expect it to travel in excess of 35 knots in any case, but has the advantage that it is a stable platform even at rough sea and high speeds, which makes especially radar operations easier. The nuclear versions could still cruise well at 25 knots, the diesel versions would be limited to 10 knots for maximum range, a pretty slow speed for a military vessel. (The [ame="http://en.wikipedia.org/wiki/Sea_Fighter"]Sea Fighter[/ame] ship reaches 55 knots, but is less than half as big as this one, and more power means more noise)

The nuclear versions on the other hand would, aside of the Greenpeace protesters in every civilian port, also have the disadvantage of a lower number of ships in the class, because of the higher costs of nuclear technology.

Because of the best option being essentially a political decision, I thought its best to make a vote on it. What do the citizens of this simulated planet think?

 

[Dambuster]

Nuclear electric. IMO range is the most important overall factor, since if your ship can't reach wherever you need it to go, it's pretty much useless. Nuclear direct would be nice for speed, but the lack of manoeuverability and higher noise would probably be a bit of a downer.

What's this ship meant to be used for, anyway?

 

[RisingFury]

Given that you're going for stealth, I'd sacrifice a bit of top speed for silence, with the nuclear-electric...

Also, I think that OF is biased towards nuclear propulsion, given the amount of interplanetary and interstellar ships we fly...

 

[T.Neo]

I second nuclear electric. Seems to score highest in all categories.

Higher cost / lower vessel numbers is indeed a problem, but if this is futuristic, the cost of nuclear technology might be lower, allowing higher production numbers.

What about another 'variant" with diesel electric or CODLAG propulsion? Or would that be too much effort, above that of just building nuclear vessels? I suppose it'd turn the ship into a whole new class...

Greenpeace protestors can be cordened off, or "roughed up" by hired undesirables if you're a little less nice, or towed out to sea and used as target practice for the ship, if you are a really despicable dictator...

 

[Urwumpe]

What's this ship meant to be used for, anyway?

By pure honesty: For transporting Annular Ramjet Cruise Missiles over the oceans and launch them. At least that was the reason why I sketched this ship one day. Pretty much a goof since the ARCM was already more a joke than a well-planned add-on. The rest came for giving it a bit more cause.

It is now essentially a floating command center and combat platform, that can fight from surface threats to space targets, but is pretty poor against submarines. It can carry two helicopters or one helicopter and two UAVs, has 16 cruise missile launchers and magazine space for about 96-128 cruise missiles, six VLS systems with 16 missiles or launcher packs each (and additional magazine space for 96 reloads, but reloading is not possible in combat), as well as two RAM launchers for point defense and four BK-30 gun pods.

The radar system is capable of detecting small satellites in 2,500 km distance and Delta-glider size targets in 60,000 km distance, the maximum range possible is 80,000 km (but very slow scan rate and small scan sector then). Additionally, it has a optical sensor station "Cyclops" on top of the "main mast", that can operate as Optical/IR telescope.

It is too large to be invincible or invisible... its stealth capabilities are just for permitting it a small chance to dodge cruise missiles, or delay detection while relying on a data link network for gathering information. It is not meant to be fighting for its own, but have a fleet of other ships and satellites around it (That is why it is a destroyer and not a cruiser). Its weapons permit fighting surface and air targets even at long distances, protecting even more specialized ships around it (For example aircraft carriers, but also ASW frigates ).

It is not really necessary to be fast, since it can launch 16 friends that can travel at Mach 6 in (freak-)wave altitude (currently 50m altitude, autopilot update to less than 15m is underway) for 600 km. Or Mach 15+ in 30 km altitude for really long range missions. (One test launch crossed the Atlantic, went low behind Ireland, zig-zagged over England and hit a target in the North Sea, with a few percent of fuel left).



---------- Post added at 11:09 PM ---------- Previous post was at 11:01 PM ----------

What about another 'variant" with diesel electric or CODLAG propulsion? Or would that be too much effort, above that of just building nuclear vessels? I suppose it'd turn the ship into a whole new class...

Would be pretty much a new class. The ship has a lot of room for growth left inside, because I had a) No clue yet what it will eventually become and b) all good ship designs had room for upgrades left. Could in theory be turned into anything nice, just a few changes to the mesh and you could have an aircraft carrier.

But the main limitation and why I ask for one: I doubt I can produce two different ship classes at a time. Maybe I can do one later, but I think it is better to do one good, instead of many bad. Also I still hope for the ship also getting VC locations, like the engineering department, which is pretty much specific for the propulsion system.

One longer distance idea I have for this one is make a bigger open-source project of it, called "Orbiter: Shadow War", but that is really not more than a few pencil sentences in my idea sketch book.

 

[Urwumpe]

I would say, we have a clear majority for nuclear electric and all people who are interested in voting must have had voted...so lets close the poll and implement the choice in the design.

 

[Sky Captain]

I'd too go for nuclear electric because endurance at sea seems to be very important. Especially if cruisers and carriers already are nuclear powered then ability to assamble an all nuclear battlegroup capable of sustained high speeds would be advantegous. Also nuclear electric means you always have plentiful electricity so you may also include in armament few free electron lasers for anti missile defence.