The great conversion of MegaTraveller starships back to High Guard

[Sigtrygg]

Current explanation appears to be that the (onboard) manoeuvre drive creates an equivalent (counter) field effect that neutralizes the effects of acceleration.

It has to counteract all perceived accelerations, that include the "g forces" from maneuvering, which would be a lot more than thrust rating of the engine.

 

[Sigtrygg]

No, canon is a grav field opposite to the perceived inertial acceleration.


But we were not discussing canon, but Sigtryggs house-rule.

The High Guard quote is not comprehensive, the Supplement 7 quote (repeated in lots of adventures) is more so.

Most ships have grav plates built into the deck flooring. These plates provide a constant artificial gravity field of 1 G.

and yet we know they can be adjusted

Acceleration compensators are also usually installed, to negate the effects of high acceleration and lateral G forces while maneuvering.

A ship's passengers would be unable to tell whether they were moving through space or grounded on a planet without looking out a viewscreen.

 

[AnotherDilbert]

Another important feature of all manoeuvre drive systems is gravitic compensators or ‘G compensators’. These enable a ship to engage in high levels of thrust without adversely affecting the crew contained inside. Ships are typically equipped with enough gravitic compensation to counter whatever Thrust score the ship has. Therefore, a ship with Thrust 4 is also equipped to compensate for 4 Gs of thrust.

HG'80, p17:
Tech level requirements for maneuver drives are imposed to cover the grav plates integral to most ship decks, and which allow high-G maneuvers while interior G-fields remain normal.

There is no contradiction between these. The words "typically" and "most" shows that it's not an intrinsic part of the tech, but an optional component.

The reason it would need to be field effect, is otherwise you'd need to incorporate it within the entire hull.

MT (errata) [quoted above] states you do have to include gravity for the whole hull.

Of course it's a field effect, just like gravity, otherwise it wouldn't affect all occupants.

 

[AnotherDilbert]

Yes it can, this is magic handwavium after all. If it can already do the impossible adding a bit more shouldn't be an issue.

OK, it's your handwavium... If you are OK with it just being magic, good for you I guess.

Yes it is absurd, but then so is artificial gravity and acceleration compensation.

Yes, artificial gravity is absurd but doesn't bend physics into a pretzel, it works in predictable ways according to Newton, even if we have no idea how the field is created.

Adding inertia manipulation, and artificial gravity manipulation of inertia, is an added layer of even more magical magic, that is completely unnecessary in my opinion.

 

[AnotherDilbert]

The High Guard quote is not comprehensive, the Supplement 7 quote (repeated in lots of adventures) is more so.

Yes, of course they can change.

The artificial gravity component counteracting the perceived inertial acceleration has to change strength and direction to counteract the momentary acceleration.

Simplified something like this:


The person in the ship feels no perceived acceleration, but accelerates with the ship. Total perceived acceleration relative to the ship is zero (except the normal 1 G gravity).

If you can (magically) make artificial gravity, you can use that gravity to counteract perceived inertial acceleration, no additional magic needed.

 

[Condottiere]

It is magic, but I can myself to believe that gravity might be artificially induced, locally.

That also means that I perceive a down and up.

Inertial compensation is the (physical) elimination of any felt (physical) movement created by the onboard thrusters.

If there are multiple thrusters/modules, they'd have to somehow unconsciously coordinate, or more likely, eliminate any acceleration created by themselves.

 

[Sigtrygg]

Yes, of course they can change.

The artificial gravity component counteracting the perceived inertial acceleration has to change strength and direction to counteract the momentary acceleration.

Simplified something like this:
View attachment 1669

The person in the ship feels no perceived acceleration, but accelerates with the ship. Total perceived acceleration relative to the ship is zero (except the normal 1 G gravity).

If you can (magically) make artificial gravity, you can use that gravity to counteract perceived inertial acceleration, no additional magic needed.

You are not taking into account the considerable "g forces" that result from a ship with a momentum due to travelling at 100km/s attempting to turn with 6g "thrust"

 

[Condottiere]

Could be that manoeuvre drive factor/zero is discounted, because the cost doesn't include the inertial compensators.

 

[AnotherDilbert]

You are not taking into account the considerable "g forces" that result from a ship with a momentum due to travelling at 100km/s attempting to turn with 6g "thrust"

I don't understand what you mean.

If you turn the drive sideways, to accelerate sideways, to change the velocity vector ("turn") you get an acceleration of 6 G. Whether that 6 G is the same direction as your current velocity vector (~momentum) or not is irrelevant. There is no water or air to push against to get more turning acceleration than drive acceleration.

If you mean rotate the ship around its centre of gravity I can only guess that is limited by the available compensator, just as the M-drive is, presumably for safety reasons. But I don't see what the ship's velocity vector (~momentum) has to do with that.

 

[AnotherDilbert]

Could be that manoeuvre drive factor/zero is discounted, because the cost doesn't include the inertial compensators.

I would assume this includes acceleration compensation, to "ensure a normal gravitational environment" under normal conditions including acceleration:

MgT HG17, p10:
Non-Gravity Hulls: Basic hulls include artificial gravity, using grav plates to ensure a normal gravitational environment for the comfort and convenience of the crew.

Doesn't explicitly include nor exclude acceleration compensation, but such is the Mongoose way...

 

[Condottiere]

Acceleration is probably a tad above that of a solar sail, but it doesn't seem sufficient to have any practical effect on either people or objects within the hull.

It's pretty clear at the moment that acceleration compensation is extruded from the same thing that causes it, the manoeuvre drive.

 

[AnotherDilbert]

It's pretty clear at the moment that acceleration compensation is extruded from the same thing that causes it, the manoeuvre drive.

Except of course where it's actually defined, e.g. TNE:

FF&S, p77:
Artificial gravity G compensators create an artificial gravity field in direct opposition to the axis of acceleration, thus negating the acceleration (up to the limit of the artificial gravity field).

As in MT it's a separate system, neither a part of the hull, nor the drive:

 

[Condottiere]

I would have no problem separating it, but Mongoose stapled it to the manoeuvre drive.

I think it's possible to unstaple it, but the option is not mentioned.

 

[AnotherDilbert]

I would have no problem separating it, but Mongoose stapled it to the manoeuvre drive.

Yes, it's a component of the manoeuvre drive system, gravitic or reaction (rocket), as far as I can tell. It's still uses artificial gravity tech.

It is even specifically noted:

Artificial Gravity uses similar technology but can only be used to generate internal gravity and does not serve as
a substitute for the G-compensation provided by a manoeuvre drive.

It's not some magical side-effect of the gravitic M-drive.

 

[Condottiere]

Only the manoeuvre drive.

So backstrapping that fifteen gee rocket onto the hull, is still going to mulch the (human) crew.

 

[AnotherDilbert]

Only the manoeuvre drive.

So backstrapping that fifteen gee rocket onto the hull, is still going to mulch the (human) crew.

HG22 doesn't say that. It does say:

Note that high-burn thrusters do not include inertial compensation for a higher thrust rating than that of a ship’s manoeuvre drive.

But all reaction drives are not HBT:

HIGH-BURN THRUSTER
A high-burn thruster is an auxiliary chemical rocket designed to give a temporary speed boost to a ship. This is done by adding a reaction drive whose Thrust is cumulative with that of the ship’s regular drive system. A reaction drive used as a high-burn thruster should require far less fuel than a ship that uses reaction drives as its main source of thrust ...

HBT reaction drive ≠ main reaction drive, silly as it may seem.


If they meant to say all reaction drives were incompatible with compensators or artificial gravity, I think they failed.

 

[Condottiere]

I'd really be cautious with high burn thrusters, rules and interpretations, that is.

As I understand it, it's basically ye reactionary rocket, cloned.

And I don't think I spotted anything that indicates inertial compensation is included with said rockets, cloned or otherwise.

And I think it's copy paste, since fuel consumption appears to be the same as a default rocket.

 

[Sigtrygg]

I don't understand what you mean.

As I said earlier - get in your car and drive in a straight line towards a bend.

Do this at 20mph, 30mph and 40 mph.

Instead of coasting keep accelerating to maintain your speed.

What do you experience inside the car.

You experience a pseudoforce throwing you sideways. in a formula 1 car this can be several "g", in a rocket accelerating at only 2g it can experience several gs as it turns

 

[AnotherDilbert]

I'd really be cautious with high burn thrusters, rules and interpretations, that is.

They made HBT rather limited, you can only add a G or two.

Originally HBTs were a retrofit (MgT1), not a part of the regular drive system, it's still listed in the Spacecraft options chapter, not the Drives chapter. In that context it makes sense that it is not covered by the regular compensators.

And I think it's copy paste, since fuel consumption appears to be the same as a default rocket.

Fuel for an hour or so is much less than fuel a main reaction drive would need, that part is understandable.

And I don't think I spotted anything that indicates inertial compensation is included with said rockets, cloned or otherwise.

I may be overthinking this, but as far as I can see compensators are a separate component:

Manoeuvre drive systems include thrusters and gravitic compensation (also called G compensators).
...
Artificial Gravity uses similar technology but can only be used to generate internal gravity and does not serve as
a substitute for the G-compensation provided by a manoeuvre drive.

Compensators is the same tech as artificial gravity, just as earlier editions.

Both Gravitic and Reaction drives contains thrusters:

Reaction drives are similar to manoeuvre drives but instead act as giant thrusters, exhausting gases that push the ship forward like today’s rockets.

The primary component of manoeuvre drives in the Charted Space universe is the thruster plate. Thruster plates use gravitic technology to move a ship without the need for exhaust propellant.

Manoeuvre Drive Systems consist of thrusters and compensators.

Manoeuvre drive systems include thrusters and gravitic compensation (also called G compensators).

Both Gravitic and Reaction drives contains thrusters.

To fit a manoeuvre or reaction drive, consult the Thrust Potential table and decide what Thrust score you want your ship to have. The figure below that Thrust score shows what percentage of the ship’s hull the manoeuvre drive consumes, in tons.

Manoeuvre and Reaction drives seems to be used somewhat interchangeably.


As far as I can see a Manoeuvre Drive System consists of a drive (either gravitic or reaction) and a compensator.


I can't see any reason artificial gravity compensators couldn't be combined with reaction drives. It's clearly not the thruster itself that performs the compensation.

 

[AnotherDilbert]

You experience a pseudoforce throwing you sideways. in a formula 1 car this can be several "g", in a rocket accelerating at only 2g it can experience several gs as it turns

No, in space there is no road to push against. Only the drive can accelerate the craft.

In a car the sideways acceleration is performed by the friction of the front wheels, no such thing in space.