1g Ships and Size:7 worlds...

[AnotherDilbert]

You do not fly like a rocket, you take off like a plane as shown in artwork, deckplans and starport layout (runways).

In LBB2?

Where are starport runways defined as standard in CT?

 

[AnotherDilbert]

Then Striker is wrong.
A streamlined ship can fly.

The rules are wrong, because you really want all starships to land on all worlds?

Or, just possibly, you house ruled just a tiny bit?

The values are whatever they need to be for a TL9 hull to achieve hypersonic flight in trace atmosphere. I wouldn't worry about heat transfer, and as for ionisation the m-drive has that covered.

Physics is wrong, because you really want all starships to land on all worlds?

But again, it's a game, and fiction to boot. It works if you want it to.

Agreed completely: Your TU works however you want, not because the LBBs told you it had to be that way, but because you house ruled it.


Why is it such a problem to say that something is a house rule?

 

[Baroun Tardis]

I think you have to establish if the Classic manoeuvre drive creates a field effect, pure thrust, or a combination of both.

I'm kinda wondering now... and this may be a pointless digression, but ...
If the M-drive makes a 'drive bubble' around the ship, such that everything inside is accelerated at the same time...
Does that include the air around the ship at the moment the drive kicks in?
If so, does that give a streamlined ship extra "wing area" since the bubble is bigger than the ship?

 

[Spinward Flow]

does that give a streamlined ship extra "wing area" since the bubble is bigger than the ship?

Depends on how much Handwavium you want to incorporate into your TU, I guess ... (beyond the obligatory minimum, that is).

 

[AnotherDilbert]

If the M-drive makes a 'drive bubble' around the ship, such that everything inside is accelerated at the same time...

Depends if we want to believe the rules in LBB2:

LBB2'81, p26:
_ _ 3. Thrust: Maneuver drive thrust is measured in Gs (gravities) expressed as a vector of both length and direction.

Thrust is a force. If the M-drive produces thrust, there are no magical bubbles or field effects necessary.

 

[mike wightman]

I can answer that question using only a single word.
You ready?
You watching?

Okay, here I go ...

DIFFERENTLY.

The way that a CTOL plane takes off is not the same as the way a VTOL helicopter takes off ... or a starship lifts off ... or a rocket launches skyward.

Sure, there may be common principles in engineering and the "physics problem" involved is relatively similar ... but the methods and processes used to "solve that problem" are not UTTERLY IDENTICAL, nor are they interchangeable, between the different varieties of craft.



Stop trying to conflate THIS ...

... with THIS ...

So you are saying all ships in your Traveller universe take off like rockets.
I am saying streamlined ships can fly like planes do since they have 1g engines and streamlined hulls. Not to mention the field the m-drive generates that can deflect radiation.

Tell you what since you have such a pleasant posting style here are a few links that may help your limited understanding:

Lifting body - Wikipedia

en.wikipedia.org

oh look here are some body shapes:
similar to the scout courier

Martin Marietta X-24 - Wikipedia

en.wikipedia.org

and these resemble the type A, course you would have to scale them up, but TL9 should manage.

Northrop M2-F3 - Wikipedia

en.wikipedia.org

 

[atpollard]

Have to agree with @AnotherDilbert here on this one, but I've got even more corroborating evidence that you neglected to look for.
LBB2.81, p26-37 deals with Space Combat and (wait for it) ... vector movement!

Specific (repeated!) mentions of gravity in vector movement are highlighted in bold text.
Note that the "standard design type A free trader" IS DIRECTLY MENTIONED within the vector movement rules.

LBB2.81, p27:


LBB2.81, p28:


LBB2.81, p28:


LBB2.81, p28-29:


LBB2.81, p31:


LBB2.81, p36-37 even has formulas and a table for easy use to determine gravity bands around planetary surfaces.
Note that the table provided on LBB2.81, p37 specifically details the surface gravity of Size: 8+ worlds (at 1.000G, 1.125G and 1.250G respectively).

• Size: 7 = 0.875G - 1G = -0.125G vector
• Size: 8 = 1.000G - 1G = +0.000G vector
• Size: 9 =1.125G - 1G = +0.125G vector
• Size: A =1.250G - 1G = +0.250G vector

Not to put too fine a point on things that ought to be beyond obvious enough already ... but you need to achieve a "negative G vector" if you want to Go To Space Today™ from a planetary surface. That's just vector math for you!

Also, LBB2.81, p28 includes this tidbit:

In other words ... THERE IS NO OVERCLOCKING of maneuver drives available for "bursts" of maneuver in CT.



Extra bonus points to anyone who reads through LBB2.81, p26-37 and realizes that "atmospheric LIFT due to streamlining" is conspicuously absent from any mention AT ALL as an available modifier to movement vectors for starships and small craft. In fact, the closest thing you can get to the notion is (wait for it) ...

LBB2.81, p34:


Last I checked, being on the surface of a planet with a standard or dense atmosphere counted as being within 1000km (10mm using the vector movement scaling) of a planet. So a Standard or Dense atmosphere adds a 0.1G drag force to vector movement under LBB2.81 (and LBB2.77 for that matter)!

So if we circle back to our vector math assumptions that resolve movement vectors and add in the atmospheric DRAG (not lift! drag!) of Standard and Dense atmospheres, we get this result:

• Size: 7 = 0.875G + 0.1G - 1G = -0.025G vector
• Size: 8 = 1.000G + 0.1G - 1G = +0.100G vector
• Size: 9 =1.125G + 0.1G - 1G = +0.225G vector
• Size: A =1.250G + 0.1G - 1G = +0.350G vector

So a "standard design type A free trader capable of 1G acceleration" CAN LIFT OFF from a Size: 7 world (0.875G) at either 0.125G vertical (Atmosphere: 5-) or agonizingly slowly at 0.025G vertical (Atmosphere: 6-9) under LBB2.81 vector movement RAW.

That same "standard design type A free trader capable of 1G acceleration" is going to remain FIRMLY MIRED in the gravity well of any Size: 8+ world ... and adding Atmosphere: 6-9 only makes things WORSE ... not better!


BECAUSE THEY DIDN'T HAVE TO.

Any tabletop wargamer who can compute vector math in their head could figure it out (for themselves!) VERY VERY QUICKLY.

I think you just proved that Airplanes cannot Fly under RAW.
No wonder the OTU rushed to develop Grav Drives and Air/rafts.

On a more serious note, NOTHING you quoted changes under the accelerate to generate lift paradigm offered by @mike wightman

The only question for a RAW argument is "where is the rule that explicitly says a 1G ship cannot lift off from a world with greater than 1G"?
If the rules are silent on the subject and one must INFER ... then the rules are silent. The classic example being "Do Laser Pistols exist?" in which there is no explicit listing for "Laser Pistol" but ONE of the editions includes Referee advice on exactly how to create a Laser Pistol.

I am all for acknowledging the RAW, but they actually have to be WRITTEN as RULES to be RAW. Inferences from other rules are GREAT (I love them and do them all the time), but it is not completely "kosher" to call them "RAW". Adding VECTORS during COMBAT does not describe a ship's "ability" or "inability" to land/takeoff. If one wants to get pedantic about physics ... FTL travel and reactionless drives are also "impossible" [yet there they are, in the rules, just like Starships using them to take-off.]

 

[Baroun Tardis]

Depends if we want to believe the rules in LBB2:

Thrust is a force. If the M-drive produces thrust, there are no magical bubbles or field effects necessary.

I guess my question is : if it produces thrust, what does it apply it to?

Rocket engine is welded into the frame of the vehicle. Light it up, it pushes on the frame... and then that pushes on the people inside, and you get squished

But does an M-drive apply thrust to everything in the hull at once?

 

[Grav_Moped]

and these resemble the type A, course you would have to scale them up, but TL9 should manage.

Northrop M2-F3 - Wikipedia

en.wikipedia.org

I'd actually considered doing up a set of deck plans for the Type A based explicitly on that.

 

[atpollard]

Rules as written say, "no".

Agreed.

... Except the RULES AS WRITTEN may not actually SAY "No." I just reread this topic and nobody seems to have ever produced that "smoking gun" rule that says that my Type A Free Trader (1G) cannot take off [and should not attempt to land] on a size 8+ world. It is always just something inferred from real world Newtonian Physics and 1G vectors. Well, THAT is NOT RAW ... that is YOUR "House Rule" (which y'all are entitles to). However, the RAW appear to be SILENT on the subject.

1. Logic says it might/should be a problem.
2. Rules say Starships fly between worlds using reactionless drives and land on/take off from planets if STREAMLINING and ATMOSPHERE permit.
3. Referee decided all maters not explicit in the rules (which IS in the RAW).

 

[Spinward Flow]

I think you just proved that Airplanes cannot Fly under RAW.

No ... that is a completely wrong perspective and understanding of the question.

Let me rephrase it this way.



Do space worthy craft follow the Space Combat Movement Rules (that can be found in LBB2.81, p26-37)?
Broadly speaking ... YES.

Do aircraft follow the Space Combat Movement Rules (that can be found in LBB2.81, p26-37)?
Broadly speaking ... NO. Aircraft use a different system (which is best detailed by Striker).

Hence the answer I provided ...

How does a plane take off?

DIFFERENTLY.

 

[Grav_Moped]

Broadly speaking ... NO. Aircraft use a different system (which is best detailed by Striker).

The issue here is ships operating in the same aerodynamic regime as aircraft.
Of course this glosses over the fact that most Traveller ships, as illustrated, aren't particularly good at being aircraft.
But that's how art goes when the artist is either unfamiliar with aerodynamics or has other objectives/priorities for their work.

 

[AnotherDilbert]

OK, I'll start from the beginning again.

... Except the RULES AS WRITTEN may not actually SAY "No." I just reread this topic and nobody seems to have ever produced that "smoking gun" rule that says that my Type A Free Trader (1G) cannot take off [and should not attempt to land] on a size 8+ world.

Smoking gun?

Striker, B2, p46:
_ _ 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.

Spacecraft does not fly using aerodynamic lift, but by drive thrust.
Spacecraft works like grav vehicles, not like aircraft.
Striker is the CT design system for grav vehicles and aircraft, so might have some idea about how that works?

It is always just something inferred from real world Newtonian Physics and 1G vectors.

Not real world physics, but the LBB2 spacecraft movement system very explicitly says:

LBB2'81, p28:
... During the movement phase, lay out the vector of the ship to determine where it will move. 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. ...

That is RAW, and also a reasonable simplification of how physics work.

Well, THAT is NOT RAW ... that is YOUR "House Rule" (which y'all are entitles to). However, the RAW appear to be SILENT on the subject.

I would say that LBB2 counts as RAW?
I would even say that Striker counts as RAW?

 

[Spinward Flow]

This is, of course, glossing over the fact that most Traveller ships, as illustrated, aren't particularly good at being aircraft.

Because they don't have to be particularly good at being aircraft!

When you've got --> ENOUGH <-- anti-gravity/contra-grav/maneuver drive thrust power to --> EXCEED LOCAL GRAVITY <-- by (and I know saying this will offend some holdouts in this thread who are being quite obstinate about this) a --> SUFFICIENT MARGIN <-- you don't have to "fly like an aircraft" ... because you can fly like a Grav Vehicle/Lighter-Than-Air Craft that relies on "bouyancy" for lifting force, rather than aerodynamic lifting forces.

With enough maneuver drive power, aerodynamic performance becomes "nice to have" rather than a limiting factor. The maneuver drive makes the ship "fly" through the air, but the hull doesn't have to be "specialized" for atmospheric performance. Capable, yes ... perfect, don't make me cackle.

The problem is when you change the parameters in play.

When the --> LOCAL GRAVITY EXCEEDS MANEUVER POWER <-- you're going to need to get more "lift" force from somewhere than the ship can provide while you're parked, whether that be at a downport berth or floating in the ocean offshore. Why? Because LOCAL GRAVITY EXCEEDS MANEUVER POWER ... so you can't VTOL to start your launch.

If your Referee is feeling "kind" towards you about your plight, you might need to make some kind of CTOL rollout for launches and landings, which would presumably involve a runway of some kind in order to get your ship above aerodynamic stall speed under local conditions of atmospheric pressure. If you're exceptionally fortunate, there might even be some kind of CATOBAR type catapult launch and arrested landing system infrastructure that your ship can make use of ... but such facilities are going to be limited to the downport (meaning they're no help with wilderness refueling where you'll need to VTOL or CTOL without any kind of ground support infrastructure).

Will such ground support infrastructure be available at type E or X downports?
Pull the other one, guv'nah.

Will such ground support infrastructure be available at type C or D downports?
Maybe ... maybe not.

Will such ground support infrastructure be available at type A or B downports?
Probably ... but honestly, it depends.



There's a reason why 1G "up" (maneuver thrust) combined with 1G "down" (gravity) yields a movement vector that looks a lot like this:

Spoiler Alert: You Are Not Going To Space Today.



You want to be thinking of Traveller starship "flight movement" more in terms of needing to do ... well ... THIS (minus the configuration changes, of course) ...

 

[coliver988]

I have to say I too am enjoying the conversation, as it raised points I never thought about. When I played in college, all streamlined ships could land and take-off. I just used the books I enjoyed as the basis, and it is SF: of course the ships can land & take off.

Now though, pretty sure I'd lean in the direction of using the M-drive to determine if they can or cannot to make it a bit more crunchy.

But carry on - it is a very interesting read!

and re:
I would say that LBB2 counts as RAW?
I would even say that Striker counts as RAW?

LBB2 certainly if I were only playing in a LBB2 world. Striker came out later, and yes, if I were to incorporate those rules, it would be RAW. But as there are a few years between the two, the question really needs to be clarified as to when do they apply as RAW. As for HG, again, depends on the game I was running . So in an LBB2 world I would actually have all ships able to take off & land if streamlined; Striker or HG, then M-drive is taken into account.

But that is IMTU. Not sure it would be a strict reading of the rules, but as mentioned way, way upstream: the RAW are just the starting point when playing any RPG game. Almost no one plays strictly RAW as most games have the rule 0 (so, err, technically, it really is RAW no matter what?)

 

[AnotherDilbert]

But does an M-drive apply thrust to everything in the hull at once?

I think not:

LBB5'79, p17:
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.

We would not need these grav plates if everything accelerated at the same rate.

I would have to conclude, without a direct quote (in CT, it's explicit in later editions), that the thrust is applied to the drive ≈ the frame of the ship.

I don't even have to invent magical field effects, apart from the explicitly mentioned grav plates artificial (magical) grav fields.

 

[Grav_Moped]

(meaning they're no help with wilderness refueling where you'll need to VTOL or CTOL without any kind of ground support infrastructure).

Martin P6M SeaMaster (wikipedia)

... and that mostly for scale, since the Convair F2Y Sea Dart was small enough to weaken the analogy.

 

[Grav_Moped]

Again, this is in the category of "yeah, it'd work if..." that assumes that starships are shaped differently than they're generally depicted (in this case, that their undersides are moderately-efficient planing hulls).

 

[Grav_Moped]

... which comes down to, if you're going to all the trouble of distorting the hull to be both optimized for hypersonic airspeeds and high-speed hydroplaning, wouldn't it be easier to use a slightly more powerful maneuver drive?

The problem is that the rules as written don't provide for that. It's literally "double or nothing".

 

[AnotherDilbert]

Let's see what we would need in the way of wings, to land a Free Trader like a current aircraft.

I'll use two comparisons, a large jetliner and a small jet fighter:

Airbus A380:
Max take off weight ~500 tonnes with a wing area of 845 m².

JAS-39 Gripen NG:
Max take off weight ~16 tonnes with a 25 m² wing area.

A Free Trader would be roughly 2000 tonnes, so would need a:
2000 / 500 × 845 ≈ 3400 m² wing area, or
2000 / 16 × 25 ≈ 3100 m² wing area.

Close enough, let's say 3000 m², heck, let's say 2000 m² for superior tech at TL-9.

2000 m², that is 1000 m² per wing, perhaps something like a 10 m wide and 100 m long wing? So, a 30 m long Free Trader with a 200 m wingspan?