General How does maneuver drive propel?

[mike wightman]

Yup, I neglected to go back and include 𝛾 in the relativistic calculation

Well the energy output of a LBB2 power plant can be rated however you want, so yes, the scout ship produces 1,000TW.

TL9 grav catalised fusion power is something isn't it, especially when you consider we haven't considered efficiency

I don't think people truly appreciate the energies being dealt with moving Traveller ships about.

Even a gravitic drive should obey energy conservation, so if you want to accelerate a 1000,000kg scout ship at 1g you still have to generate the energy to do so, we are just feeding the magical gravitcs rather than a magical fusion drive.

 

[AnotherDilbert]

Even a gravitic drive should obey energy conservation, so if you want to accelerate a 1000,000kg scout ship at 1g you still have to generate the energy to do so, we are just feeding the magical gravitcs rather than a magical fusion drive.

Yes, and no. A gravitic system is presumably not a closed system, it is connected to the local grav field.

In effect, I assume the grav drive sets up the connection to the local grav field, then lets the universe do the heavy lifting, otherwise the ship's power plant is obviously insufficient. Still magic with a different incantation...

 

[whulorigan]

In effect, I assume the grav drive sets up the connection to the local grav field, then lets the universe do the heavy lifting, otherwise the ship's power plant is obviously insufficient. Still magic with a different incantation...

That's what Droyne Coyns underneath engine mountings are for.

 

[atpollard]

Yes, and no. A gravitic system is presumably not a closed system, it is connected to the local grav field.

Yup ... like asking how much ENERGY the sail on a sailboat GENERATES and if it balances the energy needed to accelerate the boat through the water ... the SAIL captures the energy, it does not CREATE it. So too, the Grav Drive captures the energy from GRAVITY (hence the mass of the world needed for JUMP and things like Jump Shadows in certain flavors of the rules.)

Not THE ONLY explanation, but A VIABLE explanation.

 

[mike wightman]

That would work, taking energy from gravitational waves. So why do you need a fusion power plant?

 

[AnotherDilbert]

That would work, taking energy from gravitational waves. So why do you need a fusion power plant?

To maintain the gravitic "sail", to use atpollards analogy.

 

[Marcatlas]

Is there a requirement to insure a WATER ship with a three person crew operating as a tramp freighter among the Caribbean islands (or Indonesia)?
A bank holding a mortgage might want insurance, but is every small supply boat owned free and clear insured?

Different types of insurance. Banks holding a note on the freighter want insurance on the freighter itself. Ports want liability insurance in case the freighter causes damage to something else. Like a car's Comp & Collision insurance for the bank and liability insurance in case you hit another car, object or person.

 

[Marcatlas]

Yup ... like asking how much ENERGY the sail on a sailboat GENERATES and if it balances the energy needed to accelerate the boat through the water ... the SAIL captures the energy, it does not CREATE it. So too, the Grav Drive captures the energy from GRAVITY (hence the mass of the world needed for JUMP and things like Jump Shadows in certain flavors of the rules.)

Not THE ONLY explanation, but A VIABLE explanation.

Not in all versions. Only those that have a distance limit from a mass to operate the drive. Otherwise it's a closed system where the drive produces a grav well to "fall into".

 

[AnotherDilbert]

Otherwise it's a closed system where the drive produces a grav well to "fall into".

Can't be a closed system, the power plant doesn't produce remotely enough power to accelerate ships at several Gs.

Example (CT):
A Scout accelerates for a day at 2 G ≈ 20 m/s², achieving a velocity of 60×60×24×20 = 1 725 000 m/s or e_k = ½m1725000² ≈ 1.5 × 10¹⁸ J for a 1000 tonne mass.
During that time the power plant produces 500 MW × 60×60×24 s ≈ 43 × 10¹² Ws [=J].

So, we have spent 43 TJ to achieve 1 500 000 TJ kinetic energy. Either we give up on conservation of energy, or it's not a closed system.

 

[Condottiere]

What would be the definition of a closed system?

It would seem one that doesn't require the nearby presence of a (large) gravity well.

Which would leave us with the deep space drives.

 

[atpollard]

Which would leave us with the deep space drives.

Unless the effects of GRAVITY (like the Oort Cloud orbiting the Sun, or the Spiral Arm orbiting the center of the Galaxy) apply in "deep space". Then the system COULD be open (like the PP-MD combination generating the equivalent of a Grav-Sail).

 

[Marcatlas]

Can't be a closed system, the power plant doesn't produce remotely enough power to accelerate ships at several Gs.

If it is a Grav M Drive Mass doesn't matter. A 1G Gravity well pulls all objects regardless of mass at the same acceleration.

 

[Condottiere]

How tightly packed are the asteroids and comets?

Theory goes, you can use (external) lasers to propel a spacecraft.

I'm sure there is some loss of efficiency, but you could do that with the onboard laser, and presumably a reinforced solar sail.

 

[whulorigan]

That would work, taking energy from gravitational waves. So why do you need a fusion power plant?

Maybe you don't . . . Maybe all you need is a Collector . . .

 

[Condottiere]

A rag-and-bone man or ragpicker[2] (UK English) or ragman,[3] old-clothesman,[4] junkman, or junk dealer[5] (US English), also called a bone-grubber, bone-picker, chiffonnier, rag-gatherer, bag board, or totter,[6][7] collects unwanted household items and sells them to merchants. Scraps of cloth and paper could be turned into cardboard, while broken glass could be melted down and reused, and even dead cats and dogs could be skinned to make clothes. Traditionally, this was a task performed on foot, with the scavenged materials (which included rags, bones and various metals to be scrapped) kept in a small bag slung over the shoulder. Some rag-and-bone men used a cart, sometimes pulled by a horse or pony.

You have a whole bunch of smallcraft trolling around, collecting exotic particles, and other recyclable molecules, and selling them to starports.

 

[AnotherDilbert]

If it is a Grav M Drive Mass doesn't matter. A 1G Gravity well pulls all objects regardless of mass at the same acceleration.

And where did the grav field come from?

Gravity do obey conservation of momentum and energy, and Newton's laws.

The energy and momentum imparted on the ship comes from somewhere and cause a reaction on something else.


Can you lift yourself by dragging your hair?

 

[AnotherDilbert]

What would be the definition of a closed system?

In nonrelativistic classical mechanics, a closed system is a physical system that does not exchange any matter with its surroundings, and is not subject to any net force whose source is external to the system. A closed system in classical mechanics would be equivalent to an isolated system in thermodynamics. Closed systems are often used to limit the factors that can affect the results of a specific problem or experiment.

https://en.wikipedia.org/wiki/Closed_system