1g Ships and Size:7 worlds...

[AnotherDilbert]

The hits start landing once below 500000 km, several turns of that.

Yeah, I think this scenario was for Mongoose, where the shooting starts at 25-50 000 km.

Even in LBB2 civvies will not detect until 150 000 km.

If made for strictly LBB2, the green ship shouldn't start moving until the red ship is detected at 600 000 km round 14.

 

[kilemall]

Yeah, I think this scenario was for Mongoose, where the shooting starts at 25-50 000 km.

Even in LBB2 civvies will not detect until 150 000 km.

If made for strictly LBB2, the green ship shouldn't start moving until the red ship is detected at 600 000 km round 14.

Assuming they are the only sensor platforms, true. I usually assume automatic detection satellites posted out to cover the 100D limit for A and B starports, dicey for C and No for D/E.

Incidentally, a computer based orbital simulator for RPGs should be able to handle Traveller combat. Or maybe we should get a Traveller mod for KSP.

MgT weapon ranges and time scales are more logical and doable than CT, along with the ‘just see an IR source’ for initial detection. It plays differently, and depending on how fast movers are you can fairly readily have those fast passes and gone encounters.

Unless you have much greater mass/IR detection ranges, there is a lot more escape opportunity as space is a lot more opaque. OTOH combat rounds are much faster so once MgT ranges are achieved there will be a lot more shooting in less time.

 

[Condottiere]

The primary advantage of a planetary body without an atmosphere is that any hull configuration can land or take off there.

If they have the requisite thrust or lift(ers).

An atmosphere should have the advantage that with a lifting body, and/or wings, you can bite on that, and use it as a force multiplier to, in this case, to an altitude with ninety nine percent Terran norm gravitational pull.

 

[mike wightman]

This is fun

SU34 - 62m² 45 tonnes

best ratio I have found so far.

 

[atpollard]

A rocket that launches vertically?

It was a cruise missile ... and not even one of the DARPA hypersonic lifting body cruise missiles with NO WINGS. Just a regular supersonic cruise missile with tiny wings. Once velocity gets high, air starts to behave more like water and wings become less of an issue. I posit that 1000 seconds at 1 G places one at speeds where you are not flying like an aircraft with wings to generate lift any more.

 

[AnotherDilbert]

It was a cruise missile ...

Yes, a Калибр 3M-54E1 submarine based missile.
The surface version is launched from vertical box-launchers:

I would guess the submarine version is similar.

Once velocity gets high, air starts to behave more like water and wings become less of an issue. I posit that 1000 seconds at 1 G places one at speeds where you are not flying like an aircraft with wings to generate lift any more.

If I understand correctly (unlikely as it may be) the trick is not lift at supersonic speeds, but getting off the ground at reasonable speed (hence runway length), and managing drag and heat buildup.

1 G for 1000 s would give you a speed of 10 km/s, in space where there are no pesky details like gravity and friction to worry about. 1 G thrust is a shitload of power, but jet fighters with that much power still need wings to operate safely and can't come remotely close to orbital speed in atmosphere. And neither can a Tesla Plaid.

 

[atpollard]

1 G for 1000 s would give you a speed of 10 km/s, in space where there are no pesky details like gravity and friction to worry about.

The Vector Movement RAW have rules for both GRAVITY and ATMOSPHERIC FRICTION. Use them as written or create House Rules to replace them.

Whatever floats your boat.

 

[AnotherDilbert]

The Vector Movement RAW have rules for both GRAVITY and ATMOSPHERIC FRICTION.

And we are back at "the vehicle cannot move"

Use them as written or create House Rules to replace them.

Sliding frictionlessly along the planets surface is a house rule, so, yes, it's a house rule that started this discussion about house rules?

 

[whartung]

The Vector Movement RAW have rules for both GRAVITY and ATMOSPHERIC FRICTION.

But it has no rules for aerodynamic lift, and if those ships are relying on lift to take off from larger worlds, it does not cover ships taking of from vacuum or very thin atmosphere worlds.

 

[atpollard]

And we are back at "the vehicle cannot move"


Sliding frictionlessly along the planets surface is a house rule, so, yes, it's a house rule that started this discussion about house rules?

The rules are SILENT about what it means when a vector crosses the surface of the planet.
If it was a LARGE vector from deep space that crossed the surface of the planet ... the REFEREE would apply common sense and say the ship crashed. If the ship was parked at the starport and the VECTOR is 100% from Gravity ... the ref would apply common sense and say the ship just stays on the surface. If the ship attempts to taxi parallel to the planet's surface and the vector includes both THRUST and GRAVITY ... then COMMON SENSE seems to fail us.

I believe the vector should be resolved into "horizontal" and "vertical" vectors with the surface supporting the vertical component and the horizontal component being applied to acceleration along the surface [like a car driving or an airplane taxing or an ice boat sliding over a frozen pond]. You believe that the ship just sits there [as if the thrust were vertical or the ship had crashed]. The RAW say ... [nothing about it] ... so whatever anyone does is a House Rule.

 

[atpollard]

But it has no rules for aerodynamic lift, and if those ships are relying on lift to take off from larger worlds, it does not cover ships taking of from vacuum or very thin atmosphere worlds.

Others have relied upon it and I would argue that at the velocities encountered at 1000 seconds at 1G ... "angle of attack induced lift" becomes unavoidable in any atmosphere possible to roll on a size 8+ world ... however, within the framework of the abstract RAW for Vector Movement, aerodynamic lift is not "essential" if one assumes that a "Launch Vector" whose end point falls within the Planetary Diameter represents acceleration along the surface of the planetary diameter with some of the "weight" supported as a force on the surface of the planet.* By the third "Turn, the endpoint of the resultant vector WILL be above the surface of the planet and will continue to gain distance from the planet's surface (and surface gravity) with each additional turn.

It all comes down to what happens in that first turn when you apply a 1.25 G vector down and a 1G vector forward to a ship that is stationary on the surface of a planetary template. Does it move forward like a car* or sit still like a boulder*? If it sits still, then it will NEVER move. If it starts to move, then RAW, the Movement Vector will eventually be greater than the Gravity Vector.

*[the cornerstone assumption is a frictionless surface (like the spherical bovine) in RAW vs the assumption of an infinitely sticky surface in the RAW].

 

[mike wightman]

Just a thought - what happens if you set all the grav plates on the ship to -1.25g?

If you set them to 0g does that make the ship weightless?

 

[Condottiere]

Depends on current position of the spacecraft.

I'm assuming it's more zeroing gravity in relation to the current gravity external influence.

 

[Condottiere]

Gravitational plating probably is dependent on technological level on the amount of force it can exert or neutralize.

 

[mike wightman]

I'm talking about the internal fields...

has anyone ever stopped to thing about the external to the ship effects of the internal artificial gravity and acceleration compensation field(s)?

 

[Condottiere]

So was I.

I've been thinking about this ever since I started trying to understand inertial compensation.

The difference between external and internal mechanics, may be a question of scale and energy requirement.

 

[AnotherDilbert]

The rules are SILENT about what it means when a vector crosses the surface of the planet.

Yes, agreed, of course.

If it was a LARGE vector from deep space that crossed the surface of the planet ... the REFEREE would apply common sense and say the ship crashed. If the ship was parked at the starport and the VECTOR is 100% from Gravity ... the ref would apply common sense and say the ship just stays on the surface.

Not "common sense" or "reasonable", our understanding of physics is used to create additional rules or limits. With specified exceptions (Jump, M-drives, etc.) normal physics apply to the Traveller Universe, so not quite a house rule (yet).

Our understanding of physics may of course be imperfect...

If the ship attempts to taxi parallel to the planet's surface and the vector includes both THRUST and GRAVITY ... then COMMON SENSE seems to fail us.

We have to apply physics, but there are a lot of things we don't know. Physics might not be a house rule, but as soon as you fill in the blanks of what we don't know, it's a house rule.

I believe the vector should be resolved into "horizontal" and "vertical" vectors with the surface supporting the vertical component and the horizontal component being applied to acceleration along the surface [like a car driving or an airplane taxing or an ice boat sliding over a frozen pond].

Yes, if we house rule that all ships have landing wheels, that all planets have long enough runways, a specified lift- and drag-coefficient for all ships, etc, etc...

I have played along with this scenario repeatedly, as a house rule. There's nothing wrong with it, it's just a house rule.

You believe that the ship just sits there [as if the thrust were vertical or the ship had crashed]. The RAW say ... [nothing about it] ...

Striker specifies "the vehicle cannot move", and without a runway and landing wheels it wouldn't be able to by LBB2. I don't read the rules to bend them to a predetermined conclusion, but to see that they actually say.

so whatever anyone does is a House Rule.

"The vehicle cannot move" isn't a house rule...



To make all ships fly to space like aircraft, we have to assume that these 1 G craft:


have a lot better flight characteristics than this 1 G craft:

To my limited knowledge, jet fighters don't generally fall off the Earth to end up in orbit. There's a reason we still faff about with rockets to go to space?



We have to assume that this:

~2000 tonne 1 G craft with a perhaps 500 m² lifting body can routinely take off on its aerodynamic lift in a VThin (10% Earth pressure?, about 15 km altitude?) atmosphere.

As far as I know 1 km (~3300') altitude makes a lot of difference to take-off speed and therefore needed runway length. 15 km would be a dramatic difference?


My limited, flawed grasp of fluid dynamics would suggest that all of that is rather improbable.

 

[AnotherDilbert]

Just a thought - what happens if you set all the grav plates on the ship to -1.25g?

The only thing we know is:

LBB5'79: Tech level requirements for maneuver drives are imposed to cover the grav-plates integral to most ship decks which allow high-G maneuvers while the interior G-fields remain normal.

and

LBB2'81: If the exact midpoint of the vector lies in a gravity band, a gravity vector will be added to the course vector to create a new vector.

Grav plates affects internal grav fields, but the ship is still affected by gravity as normal. The ship accelerates as usual (including by gravity), but you are not tossed about inside it.

The key word is "interior G-fields remain normal", i think.

If you set them to 0g does that make the ship weightless?

You are weightless inside the ship, the ship isn't weightless. If you are parked on a planet, the ship will be firmly grounded, but you will perceive weightlessness, as you are accelerated downwards by the planets gravity and accelerated upwards by the "grav-plates" for a net zero acceleration perceived. OK, there is probably some "interpretation" by me in there, but I can't see any other simple logical combination of the two quotes above..



I would interpret that as the grav-plates is a small, low-powered system that can move about a few people, not a few thousand tonnes of starship.

 

[AnotherDilbert]

has anyone ever stopped to thing about the external to the ship effects of the internal artificial gravity and acceleration compensation field(s)?

Yes, of course.

If our current understanding of physics is any guide, they just superimpose. -3 G (rearward) + 3 G (forwards) = 0 G perceived.

Inertial compensation = Acceleration compensation is just acceleration in the opposite direction, and by F=ma a force field in the opposite direction. Just like gravity...

 

[atpollard]

Striker specifies "the vehicle cannot move"

Striker specifies the STARSHIP is in ORBIT ... that is what keeps frustrating me about your references to Striker when discussing the LBB2 Combat Vector Movement. You are IGNORING the clearest STRIKER RAW of all ... Striker does not apply to a 1G ship on a size 8+ world! Striker says a Grav Vehicle (Grav Tank, G Carrier, Air Raft) cannot move. MT and FF&S (written by the Striker Gang to expand Striker to Starships) explains that Grav Vehicle "Drives" are different than Starship "Drives" [that whole deep space vs need planetary mass thing].