Anti-gravity <> anti-mass

[phavoc]

You are right. Speed of the ships depends on the cargo (and price of fuel). Cruise ships average around 20knts or so. Containers ships about 25, and bulk carriers/tankers around 10-14. Even a small decrease in speed can really reduce your fuel burn.

Torps have always had a speed advantage, though I think the Alfa class Russian SSN has a speed close to 45kts with full power, or somewhere close to that. It's damn fast, and probably more than a slight bit noisy at that speed. Can't outrun an ASROC, but you might be able to get away from one or two torps. Though the clever Russians have a undrewater rocket-powered torpedo that gets up to about 200kts, or more. It's called the Shkval. It uses super-cavitating tech, the same that some recent articles talked about the Chinese wanting to use to build a 1,000kph super-sub. Dunno much about their maneuverability though, I suspect it's not necessarily the nimblest of things though with water being so much more denser than air.

Depending on where the ships are able to do their deployments, you are totally right. In the past task forces have deployed at high speed, and then gotten to their area of operations with low tanks. The idea being that their support ships would be encountered in-transit or when they got there (assuming no friendly port was around) to top them off. A fleet's supply train is always it's weakest link.

 

[Anonymous]

I suspect but cannot prove, that if you looked at the speed of the LONG range mode of certain torpedoes around the 1980s, it would be around 30 kn.

Seems ages ago but warships live a long time. I believe the British fought the Falklands War (1982) with the same torpedo they fought World War II with, maybe updated a bit.

 

[phavoc]

I suspect but cannot prove, that if you looked at the speed of the LONG range mode of certain torpedoes around the 1980s, it would be around 30 kn.

Seems ages ago but warships live a long time. I believe the British fought the Falklands War (1982) with the same torpedo they fought World War II with, maybe updated a bit.

The Mk 48 (with it's various upgrades) has been around since the 70s. It's the standard USN torp. I think it's top speed is around 50 kts, but it can be stepped down speed wise to give it more range. Torps in WW2 (based on German design, not the crap we started the war with) could do 30kts.

The Japanese Long Lance was a beauty of a torpedo. It had a top speed of about 50kts and a HUGE range for the time - about 40,000 yards (again with a stepped-down speed). Effective range was a little more than half that, but at Savo Sound the USN learned the hard way just how long ranged those things were.

 

[Condottiere]

I hear the Long Lance is over-rated, and more of a surprise factor for Allied ships early in the Great Patriotic War.

Also, I suspect in the next war, it will be drones and cruise missiles chasing ships in open waters, besides the hypersonic ballistic carrier-killer missiles the Chinese keep threatening to develop.

 

[Anonymous]

Also, I suspect in the next war, it will be drones and cruise missiles chasing ships in open waters, besides the hypersonic ballistic carrier-killer missiles the Chinese keep threatening to develop.

This is clearly untrue. We learned from Civilisation V that the last war began when two Indian spearmen attacked a Mayan tank. The war was still raging 15 years later when the Mayans blasted off for Alpha Centauri and lost contact with Earth.

 

[simonh]

I didn't make the question clear enough, does this negative curve also allow the ship to ignore the effects of a planet's gravity well and assuming that places the machines on the "underside" of the ship, did you tweak deck plans or just say it was built into the hull?

And, what should we call the heavy machinery at the back of the ship that pushes us forward?

:wink:

All gravity, whether positive or negative obeys the inverse square law with distance, a planet is a much larger object than an antigrav vehicle, so you will have to travel a lot further from a planet that you would from an antigrav vehicle to diminish its gravity by the same amount.

I'm not sure I follow this. Newtonian and relativistic gravitation doesn't care what the dimensions of an object are when determining how it's gravity field weakens over distance, only what it's mass is. Technically, if a vehicle is generating a virtual mass causing a 1G gravity field in it's local area, the field should reduce with distance in exactly the same way that the planet's field does. We can hand-wave that away by saying that our artificial gravity field has a different geometry to one generated by a real mass, with a more rapid reduction in field strength at distance, but the size of the vehicle isn't a factor in this.

I would say that a grav vehicle flies because it pushes down on matter mostly that is close to it, so long as their is matter nearby, it can continue to ascend, whether that matter is air or ground or water, it doesn't matter, but when the matter surrounding it diminishes to a vacuum, then that antigrav vehicle has reached its operational height, it can maybe push itself into orbit, but that's it, it can't travel any farther without a maneuver drive.

If the drive is generating a field that pushes everything around it downwards, why doesn't it push the rest of the vehicle downwards?

Simon Hibbs

 

[Anonymous]

Gravity does obey the inverse square law. The attraction is 1/distance**2. Newton's Law of Universal Gravitation is that the attraction between two masses is directly proportional to the magnitude of the masses and inversely proportional to the square of their distance apart.

The size of the object is relevant in that objects aren't point particles and their gravitiational attraction will vary as their size and composition changes. For example, gravity varies over the surface of the Earth as you go up and down mountains, or you pass over deposits of heavier metals such as iron.

The explanation I saw in (I think TNE?) of antigrav was that it reduces the mass of the vehicle. It doesn't actually push anything. However I'm certain this varies depending on which version of Traveller you have.

The answer to your question is because you attached the drive to the vehicle. Think of it like a rotor. It pushes down and the vehicle goes up because the rotor is attached to the vehicle.

 

[simonh]

The answer to your question is because you attached the drive to the vehicle. Think of it like a rotor. It pushes down and the vehicle goes up because the rotor is attached to the vehicle.

The rotor is pushing a large mass of air downwards, and the equal and opposite reaction is for the rotor to be pushed upwards, pulling the vehicle along with it. But some of that air does push against the top of the helicopter and increase it's resistance to being pulled up. This is why helicopters are streamlined vertically (to varying degrees), to present a lower profile to the down-wash of air. There's no magic that stops the helicopter being susceptible to the laws of nature just because it's attached to the rotor.

We talk about gravity affecting objects, but actually it operates at the sub-atomic level on particles. The field wouldn't know or care how the protons, neutrons and electrons of any given object are or are not bound to those of other objects. It only cares about which particles are in the field and acts on them.

If you want to get into specifics, what about people that aren't bonded directly to the hull? How about a ball being tossed back and forth between two people in the vehicle? What if someone in the vehicle jumps up off the deck? Do these things suddenly become susceptible to the field? For that matter, surely the drive itself would be inside the field it creates.

Simon Hibbs

 

[Anonymous]

The bottom of the craft is closer to the planet, and therefore the gravity at the top of the field is lower than at the bottom. Pushing equally in all directions will therefore cause the craft to rise, in a similar manner to how bouyancy works.

There is also no requirement that the field is equal strength in all directions.

 

[Condottiere]

The way I see it, air/raft lifters need an existing gravitational field to interact with.

Whatever the usual drives that spaceships use, don't need that, and in fact, it effects their manoeuvering.

 

[dragoner]

Grav plates kind of break the paradigm, do they stop working in deep space, inertial dampers?

 

[FallingPhoenix]

Strategically a naval task force is as fast as the diesel-powered support ship carrying its fuel and ammo.

Well, then we obviously need nuclear supply ships!

 

[Reynard]

From sorting the myriad bits and pieces, the lifters are part of the maneuver drive system acting as a VTOL for a ship while the main maneuver section is the gross motive unit for space travel with the power for quick intersystem travel. The gravitic field for inertial dampening is another gravity manipulation principle considered part of a ship's life support rather than motion system though both interact.

 

[Reynard]

"Well, then we obviously need nuclear supply ships!"

Those are economically efficient targets of opportunity.

 

[Condottiere]

If they can locate and catch them.

 

[phavoc]

From sorting the myriad bits and pieces, the lifters are part of the maneuver drive system acting as a VTOL for a ship while the main maneuver section is the gross motive unit for space travel with the power for quick intersystem travel. The gravitic field for inertial dampening is another gravity manipulation principle considered part of a ship's life support rather than motion system though both interact.

I have always had roughly the same idea. I had even consulted my DGP SOM and it talked about the HepLAR plates and their grav field, but if my fuzzy memory recalls correctly, it was a bit of a contradiction with the angle of the grav fields and such. the internal compensator had to be at an oblique angle to the drive field. But the manual never seemed to explain that very well. Though maybe it did and I just don't remember.

 

[simonh]

Strategically a naval task force is as fast as the diesel-powered support ship carrying its fuel and ammo.

Well, then we obviously need nuclear supply ships!

If your logistics strategy is to have only one support group and supply base, maybe.

This is why the US and the UK are so keen on keeping their scattered global network of naval bases operational. It's also why Russia is so keen on supporting Assad in Syria - Tartus is their only naval supply base in the Mediterranean. If your supply line to one depot and supply group is getting too long, it's nice to be able to switch to using another.

Simon Hibbs

 

[Condottiere]

I was fairly sure that the Russians would switch to Cyprus; there are converging strategic interests for the Russians' current intervention.

 

[simonh]

The bottom of the craft is closer to the planet, and therefore the gravity at the top of the field is lower than at the bottom. Pushing equally in all directions will therefore cause the craft to rise, in a similar manner to how bouyancy works.

There is also no requirement that the field is equal strength in all directions.

Won't a force pushing equally in all directions just cancel itself out? Or will it push the structure of the vessel apart? I'm having trouble visualizing this as it sounds totally different to what was described before.

Simon Hibbs

 

[Condottiere]

I guess we first have to figure out how the drives work, then we can discuss if it makes sense.