1g Ships and Size:7 worlds...

[Spinward Flow]

Here's a fun little exercise for everyone who enjoys RAW Fundamentalism.

We all know (and agree) that streamlining is required to ENTER atmospheres. There are multiple citations across multiple books stating this to be so.

Can anyone cite a source (in CT, preferably) where CT explicitly says that Streamlining is of ANY ASSISTANCE ... at all ... in LEAVING atmospheres?



Go in ... sure.
Get out ... that's different. Related, sure ... but still different.

Ingress does not equal egress (and all that jazz).



Can anyone quote some RAW from CT which uneqivocably states that streamlining assists with "lifting" a spacecraft (not a Striker vehicle) out of an atmosphere from surface to orbit?
Anyone?

 

[AnotherDilbert]

But, again, an Air Raft can reach orbit in <UPP Size Code> hours. There's no mention of different air rafts for different worlds of different gravities.

Look at the LBB3 descriptions of Ground Car or Helicopter, e.g.:

LBB3'77, p17:
_ _ Air/Raft skill may be used beneficially by characters for all air vehicles; unlike as with land vehicles, persons without air/raft skill cannot operate air vehicles.
_ _ The following examples of air vehicles are given to indicate characteristics and costs:

Primitive Biplane Aircraft (4) CR 200,000. ...

Fixed Wing Aircraft (5) CR 1,000,000. A twin jet aircraft monoplane with a crew of 2 and capacity for 6 passengers. The aircraft weighs 5 tons with a cargo capacity of 5 tons. Wingspan: 15 meters. Length: 15 meters. Normal cruise speed is 600 km per hour with a range of 3500 km. Referee's options for the craft could include a seaplane version, hardpoints for ordnance or auto-cannon, larger versions, etc.


Helicopter (6) CR 1,000,000. Single engine rotary wing aircraft capable of vertical take-off and landing, as well as maneuverability in tight places. This craft weighs one ton with a capacity for one ton of cargo and passengers. Range: 600 km; maximum speed: 250 km per hour. A larger version would be a twin engine cargo helicopter costing CR 2,000,000; weighing ten tons, and capable of carrying ten tons.

Air/Raft (8) CR 6,000,000. Also known as a flier, the air/raft relies on solid state null gravity modules for lift and propulsion. Four independent, individually replaceable modules (CR 1,000,000 each) insure a maximum of safety. Loss of one module reduces lift by one-quarter. The standard air/raft weighs 4 tons and can carry a payload of up to 4 tons including pilot and passengers. Cruise speed is 100 km per hour with unlimited range and endurance. Normally, air/rafts are open topped; the referee may allow a pressurized version or such options as gun mounts, searchlights, crash cushions or larger capacities at higher prices.

Does this describe all the characteristics and limitations of either Helicopters or Air/rafts?
How does gravity or air density affect the performance of the Helicopter? Can all helicopters land at all altitudes (air pressures)?
Is there only one model of Helicopter in the universe?

No, of course a short paragraph can't describe all Helicopters or all Air/rafts in detail. It's explicitly just an example to indicate what the characteristics might be. I think you are expecting a bit too much of LBB3.

Striker has a lot more space and describes this in more detail (but still very simplified). But of course that doesn't count...
In high gravity, the air/raft can carry a bit less cargo, in low gravity it can carry a bit more. With no cargo it's nippier and faster than when it's fully loaded. No big deal...

Exactly. This is the "fantasy" element of the Traveller universe.

Sure, if that's what you want. It just wasn't LBB2 that said it.

 

[atpollard]

Grav vehicles, just like spacecraft or helicopters need thrust greater than local gravity to fly. As the rules (and physics) say. As I have quoted a few times in this thread.

Aircraft and HTOL Spacecraft do not fly when they accelerate down a runway to reach “takeoff speed” … they operate more like a car with the wheels supporting their weight against the pull of gravity.

 

[Enoki]

Grav vehicles, just like spacecraft or helicopters need thrust greater than local gravity to fly. As the rules (and physics) say. As I have quoted a few times in this thread.

Thrust, no. Lift, yes. If it required just thrust, a hot air balloon would never fly... Just like a ship can float on water, a balloon can float on an ocean of air. A starship with some amount of displacement will do the same, particularly if you have grav negating ability. So, the ship might only require .75G of negation to 'float' on the ocean of air it's in... It's shape doesn't matter. What matters is it's displacement (volume).

 

[mike wightman]

Here's a fun little exercise for everyone who enjoys RAW Fundamentalism.

We all know (and agree) that streamlining is required to ENTER atmospheres. There are multiple citations across multiple books stating this to be so.

Can anyone cite a source (in CT, preferably) where CT explicitly says that Streamlining is of ANY ASSISTANCE ... at all ... in LEAVING atmospheres?



Go in ... sure.
Get out ... that's different. Related, sure ... but still different.

Ingress does not equal egress (and all that jazz).



Can anyone quote some RAW from CT which uneqivocably states that streamlining assists with "lifting" a spacecraft (not a Striker vehicle) out of an atmosphere from surface to orbit?
Anyone?

Can you provide a similar direct quote of where it says ships can't fly like planes, and a quote that forbids a 1g ship from taking off from a size 8+ world

go on

put up or shut up

Basic physics tells us that a streamlined shape can generate lift, the shape of ships, their deckplans and art work shows them flying like planes. Just because the word lift isn't used does not stop grav vehicles, planes and helicopters flying in the Traveller universe, but for some reason known only to a select few streamlined starships can not generate lift and fly.

 

[mike wightman]

Look at the LBB3 descriptions of Ground Car or Helicopter, e.g.:

Does this describe all the characteristics and limitations of either Helicopters or Air/rafts?
How does gravity or air density affect the performance of the Helicopter? Can all helicopters land at all altitudes (air pressures)?
Is there only one model of Helicopter in the universe?

No, of course a short paragraph can't describe all Helicopters or all Air/rafts in detail. It's explicitly just an example to indicate what the characteristics might be. I think you are expecting a bit too much of LBB3.

Striker has a lot more space and describes this in more detail (but still very simplified). But of course that doesn't count...
In high gravity, the air/raft can carry a bit less cargo, in low gravity it can carry a bit more. With no cargo it's nippier and faster than when it's fully loaded. No big deal...



Sure, if that's what you want. It just wasn't LBB2 that said it.

So you are saying that helicopters and planes can generate lift, and that we can take their flight characteristics from here in the real world but for some reason streamlined ships can't - which defies logic and the laws of physics.

 

[Captain_Ahab]

not a great argument, imho

"Can you provide a similar direct quote of where it says ships have mass. No? Then, gravity has no effect on them and they have no inertia."

or else apply logic and basic laws of physics to everything in Traveller, leading to some unexpected and unwanted results

ultimately, these are houserules and not RAW, and lead to increasing levels of complexity

 

[atpollard]

Here's a fun little exercise for everyone who enjoys RAW Fundamentalism.

Nobody enjoys "RAW Fundamentalism" ... some of us object when people claim the RULE BOOK SAYS something that it does not actually SAY, but must be inferred from rules for other things. We are being pedantic about the actual definition of a "RAW".

• IMTU, the G-rating of a ship must exceed local gravity or you take the Shuttle from orbit. I just don't claim that the RULES explicitly state that (ie. R.A.W.).
• IMTU there is also no Third Imperium (also not RAW).

This is not about demanding adherence to the RAW, it is about calling what is actually WRITTEN the RAW and not the eisegesis of what is written the RAW. There is very little RAW about starships taking off from planets ... mostly just references to the fact that they do. So the burden of proof for a claim that starships cannot take off from many worlds rests with a requirement for a clear RAW that says that. LBB2:77 pg10-11 list the distance and travel time from surface to orbit at 1G in a RULE AS WRITTEN.

 

[AnotherDilbert]

Grav vehicles, just like spacecraft or helicopters need thrust greater than local gravity to fly. As the rules (and physics) say. As I have quoted a few times in this thread.

Aircraft and HTOL Spacecraft do not fly when they accelerate down a runway to reach “takeoff speed” … they operate more like a car with the wheels supporting their weight against the pull of gravity.

Grav vehicles and helicopters don't generally use runways to accelerate, as they don't rely on aerodynamic lift from wings. Striker says spaceships fly like grav vehicles.

HOTL spacecraft are not defined by any CT Traveller rule, but you can of course house rule them ant any time you want.

 

[AnotherDilbert]

Grav vehicles, just like spacecraft or helicopters need thrust greater than local gravity to fly. As the rules (and physics) say. As I have quoted a few times in this thread.

Thrust, no. Lift, yes. If it required just thrust, a hot air balloon would never fly... Just like a ship can float on water, a balloon can float on an ocean of air.

I used thrust for "force generated by the drive system" as in "that jet engine has a thrust of 100 kN". That thrust can be directed up, down, or sideways. OK, that is a bit sloppy.

Lift is technically an aerodynamical force perpendicular to the airflow over the aerodynamic body, e.g. wing. It isn't necessarily anti-parallel to the gravity vector.

So, what I meant was a grav vehicle directs thrust from it's drive downwards to counteract gravity, and any excess backwards for propulsion. If drive thrust is less than the weight (local gravity) of the vehicle it can't get off the ground and fly. Just like a helicopter.

A starship with some amount of displacement will do the same, particularly if you have grav negating ability. So, the ship might only require .75G of negation to 'float' on the ocean of air it's in... It's shape doesn't matter. What matters is it's displacement (volume).

Yes, if you house ruled a grav drive in spacecraft.
Buoyancy from the air is orders of magnitude too small to matter to compact heavy objects like Traveller spaceships.

 

[AnotherDilbert]

So you are saying that helicopters and planes can generate lift, and that we can take their flight characteristics from here in the real world but for some reason streamlined ships can't - ...

Yes, we know how fixed wing aircraft and helicopters work. There are many different aircraft and their complete characteristics can't be described in a short paragraph. Presumably the same is true for grav vehicles.

... which defies logic and the laws of physics.

That defies your house rules, yes.

Can a streamlined car fly? The Laws of Physics says no.
Streamlined ≠ massive lift from wings or other lifting bodies.
Streamlined generally means low drag coefficient.
https://dictionary.cambridge.org/dictionary/english/streamlining

As MT put it:

Without power, a streamlined craft drops like a rock.

CT Striker 1981, B2, p41:
_ _ A. Movement: The movement rate of a spaceship is determined in the same way as that for a grav vehicle; the ship's maneuver drive rating is used as its G value. A ship with a G rating equal to or less than the planetary gravity may not take part in combat actions except from orbit.

A spaceship with lower M-drive rating than local gravity can't fly.
It's RAW whether you like it or not. You can of course disregard it, as a house rule.

 

[Spinward Flow]

Can you provide a similar direct quote of where it says ships can't fly like planes, and a quote that forbids a 1g ship from taking off from a size 8+ world

go on

put up or shut up

Already done. Repeatedly.
Here's an invoice for you.

Reply #238
Reply #360
Reply #411

If LBB1.77 and LBB2.81 are insufficiently authoritative for you as sources ... {shrug} ... that is quite literally Not My Problem.

Just because you don't like the answers is not a good enough reason to pretend the answers haven't already been given, proven and cited (with references!) before in a conversation you have been participating in heavily.

Also, nice trick trying to put the onus of proving a negative onto me ("ships can't fly like planes") rather than accepting the onus of proving the positive ("streamlined ships fly exactly like planes") yourself. Extra bonus points for trying to use an absence of text denying your assertion as proof that your assertion is therefore valid.

My position is that maneuver drives are rated in "absolute values" of acceleration (1G, 2G, etc.) ... rather than in "relative values" determined by whatever gravity well happens to be nearby (1x, 2x, etc.). I assert that this "absolute value" in maneuver drive acceleration is relevant in the context of takeoff/landing potential (of the YES/NO variety) at the bottom of a gravity well on a planetary surface. The fact that the interplanetary travel time formula of LBB2 (77 and 81) is set up such that maneuver drive performance is a CONSTANT rather than a VARIABLE tends to buttress my case.

You (obviously) disagree.



Guess we'll just have to leave it there.

 

[AnotherDilbert]

This is not about demanding adherence to the RAW, it is about calling what is actually WRITTEN the RAW and not the eisegesis of what is written the RAW. There is very little RAW about starships taking off from planets ... mostly just references to the fact that they do. So the burden of proof for a claim that starships cannot take off from many worlds rests with a requirement for a clear RAW that says that.

Striker:

_ _ A. Movement: The movement rate of a spaceship is determined in the same way as that for a grav vehicle; the ship's maneuver drive rating is used as its G value. A ship with a G rating equal to or less than the planetary gravity may not take part in combat actions except from orbit.

_ _ 1. Grav Vehicle Maneuver Gs: A grav vehicle has Gs of acceleration equal to its thrust in tons divided by its weight, also in tons. One G is needed to keep the vehicle in the air (and if its thrust is less than one G, the vehicle cannot move); thrust in excess of one G is used for maneuver. Thus to find maneuver Gs, subtract one from the total G value.

Rule 53: Planetary Environment
_ _ The basic Striker rules describe conditions on an Earth-like planet (in Traveller terms, size 8, with a standard atmosphere). Planets with different sizes, gravities, and atmospheres will have various effects, as explained below.
...
_ _ 1. Movement: For the movement of all ground vehicles, ... Grav vehicles require a more complicated determination of movement. The movement rate is determined as outlined in the vehicle design rules in Book 3, but instead of subtracting 1 from the G-rating of the vehicle's drives, the local gravity is subtracted instead.

This, just like LBB2, says that spaceships with a lower M-drive rating than local gravity can't fly, they can't take off, literally "the vehicle cannot move". How much clearer do you want it?

Gravity affects spacecraft in Traveller. Physics doesn't disappear in a cloud of unicorn farts around spacecraft.

LBB2:77 pg10-11 list the distance and travel time from surface to orbit at 1G in a RULE AS WRITTEN.

No, this does not describe orbital manoeuvres (it's LBB2'81, p10):


LBB2'77, p1 says:

No, that doesn't describe orbital manoeuvres either.

Who is drawing improbable implications from this text?

 

[atpollard]

Grav vehicles and helicopters don't generally use runways to accelerate, as they don't rely on aerodynamic lift from wings.

... says your house rule. The RAW say no such thing (they are silent on the issue of aerodynamic lift and runways). The Deckplans are NOT, as a rule, Tail-sitters but far more "Airplane-like".

 

[atpollard]

Striker says spaceships fly like grav vehicles.

A half-truth. Striker does not deal with surface to Orbit travel ... it contains rules for MINIATURES and small unit combat. The comments about Spaceships refer to how to apply the STRIKER COMBAT RULES to them ... treat them like Grav Vehicles (Grav Tanks and Grav APCs are given extensive treatment in the Striker rules).

 

[atpollard]

HOTL spacecraft are not defined by any CT Traveller rule, but you can of course house rule them any time you want.

Nor are VTOL spacecraft defined by any CT Traveller Rule, are they?
That is MY POINT, your rules for VTOL Starships are as much a "House Rule" as any HTOL Starship rule that I might present. More so, in fact, because the PLANS show the DRIVES in the REAR of the ship and you have them thrusting DOWN for takeoff (VTOL) and FORWARD for interplanetary travel. I have at least posited a constant FORWARD thrust.

I only mentioned HTOL because it was questioned how a ship could take off under the COMBAT VECTOR MOVEMENT RAW ... so I read the RAW and launched the ship tangential to the planet rather than perpendicular ... then followed the RAW for Vector movement and Gravity bands.

 

[Spinward Flow]

The RAW say no such thing (they are silent on the issue of aerodynamic lift and runways).

The copium ... why are you increasing the dosage to deny the already beyond obvious?

The Deckplans are NOT, as a rule, Tail-sitters but far more "Airplane-like".

Which works just fine for MOST worlds ... also known as Size: 7- where 1G maneuver power can exceed local gravity, enabling Gravitic VTOL maneuvering.

Please do not conflate "works in MOST places" with the broader notion of "therefore works in ALL places" ...

Striker does not deal with surface to Orbit travel

The comments about Spaceships refer to how to apply the STRIKER COMBAT RULES to them ... treat them like Grav Vehicles (Grav Tanks and Grav APCs are given extensive treatment in the Striker rules).

Wait wait wait ... hold the phone.

Starship movement rules don't apply to atmospheres and planetary surfaces, even though any plain text reading of LBB2.81 vector movement makes it absolutely clear that they do ...

And grav vehicle movement rules don't apply to surface to orbit travel either, especially if times are given for grav vehicles to reach orbit.



Yeah, I think we're done here.

 

[atpollard]

Striker:

"Striker fills an important place in the Traveller universe - rules for ground combat with 15mm figures and vehicles."​

​

"The true value of Striker, however, lies with the advanced rules. A complete system for designing armored vehicles and aircraft at different tech levels is presented, along with air-to-air and air-to-ground combat rules. The package contains everything a Traveller adventurer needs for campaigning with miniatures."​

- Striker Book 1, pg 0

It is helpful to remember what Striker IS and what it IS NOT.
Rules for flying your Starship from the SURFACE to ORBIT are found in LBB2:77, pg 10-11. (10,000 km in 2000 seconds at 1G)
[Miniatures, vector movement, planetary gravity bands and "aerodynamic lift" not required ... you are free to add any and all of those as House Rules IYTU with my blessings, but they are not essential parts of the RAW for getting to orbit.]

 

[atpollard]

Starship movement rules don't apply to atmospheres and planetary surfaces, even though any plain text reading of LBB2.81 vector movement makes it absolutely clear that they do ...

I used your LBB2:77 vector movement rules to take off. They PROVE that you cannot lift off VERTICAL, but placing the thrust vector horizontal and accelerating until the vector clears the gravity band works as well as any part of the whole clunky Vector Movement system. I hate all of it, but that doesn't mean that the system is wrong ... just that I don't like it.

Why are YOU insisting on pointing the thrust vector straight up? What in the rules says that is required? What is wrong with skimming across the ocean like a stone to build up velocity?

What about LBB2:77 pg 10-11? Does it say that a 1G ship can fly from Surface to Orbit (10,000 km) in 2000 seconds or not? Is that a rule about the ability of a Starships to take-off or not? Does that IMPLY that planetary Gravity does not hamper launch to orbit (for whatever reason) or not?

Your accusations against me ring false. I disagree with your conclusions, that is true, but I have examined them and tested them and weighed the IMPLIED consequences of a space vector movement system (that does not prevent horizontal takeoff) against the CLEAR rules for a ship traveling from Surface to Orbit presented in LBB2.

• Vector Movement prevents VERTICAL takeoff, but not HORIZONTAL. (try it)
• STRIKER is about MINIATURES COMBAT and the Starship rules govern which starships may participate by maneuvering like "Grav Tanks and Grav APCs ... Starships with 1G MD may not participate in Combat. [That is not the same as not being able to make a slow, clumsy climb to orbit with so little agility that a WW2 Fighter Plane with Korean War era missiles could shoot it down.]
• LBB 1-5 are clear that ships do fly to orbit and that Streamlining impacts which ships may enter which atmospheres. They say NOTHING about MANY ships being unable to land on MANY worlds (something important enough that it should have been mentioned). 2000 seconds at 1G from Surface to Orbit ... that is what the rules say. Why completely IGNORE the one CLEAR rule?

 

[AnotherDilbert]

Grav vehicles and helicopters don't generally use runways to accelerate, as they don't rely on aerodynamic lift from wings. Striker says spaceships fly like grav vehicles.

... says your house rule. The RAW say no such thing (they are silent on the issue of aerodynamic lift and runways). The Deckplans are NOT, as a rule, Tail-sitters but far more "Airplane-like".

Yes, the obscure house rule called LBB3:

Air/Raft (8) CR 6,000,000. Also known as a flier, the air/raft relies on solid state null gravity modules for lift and propulsion. Four independent, individually replaceable modules (CR 1,000,000 each) insure a maximum of safety. Loss of one mod- ule reduces lift by one-quarter.

That can't possibly apply to grav vehicles, right? This must mean that grav vehicles fly using aerodynamic lift from their large wings, no doubt!


And the irrelevant book in Striker:

_ _ 1. Grav Vehicle Maneuver Gs: A grav vehicle has Gs of acceleration equal to its thrust in tons divided by its weight, also in tons. One G is needed to keep the vehicle in the air (and if its thrust is less than one G, the vehicle cannot move); thrust in excess of one G is used for maneuver. Thus to find maneuver Gs, subtract one from the total G value.

That just states "the vehicle cannot move", that obviously means the vehicle can move if we just apply enough unicorn farts.