1g Ships and Size:7 worlds...

[mike wightman]

You have a good point. But, that too, is calculable.

On Earth, at least, to reach the International Space Station, (the altitude required for a 1G capable starship to be able to pull away from a 1.125 G gravity well,) a rocket has to reach a speed of 25,000 mph... or Mach 32.6.

I see no reason a TL9 1g ship can not achieve a hypersonic speed of mach 32+.

 

[mike wightman]

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

Perhaps you should try it yourself by the rules as written.
As soon as the ship accelerates and flies off the ground it is in the 0.75g band (or are you insisting that planes can't fly). That gives it a 25mm vector after subtracting for gravity.
Next turn it is in the 0.5g band, so its total vector is 75mm
Next turn it is in the 0.25g band, total vector 150mm and so on.
Not as fast to orbit as a 2g ship following a rocket trajectory (which is never vertical the whole trip)

Give LBB2 combat by the rules as written a try, including making planetary templates.

 

[AnotherDilbert]

No, I am using the rules laid out in the space combat games. So are you saying lift and drag do not exist in the Traveller setting and that planes therefore can't fly?

No, of course not. Neither am I saying 2000 tonne bricks are very good aerodynamically.
Aircraft works as usual, as detailed in Striker...

Striker is not LBB2 and deals with grav modules not maneuver drives, it contradicts what is already stated for ships (in that they can enter atmospheres).

Striker is Traveller and CT, contemporary with LBB2'81, and the quoted rule applies specifically to spaceships.

Striker, 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.

Or are you saying 1g ships can't fly at all regardless of streamling because of what Striker says?

No, but Striker says a ship must have a higher G-rating than local gravity: A 0.5 G ship would float happily in a local gravity of 0.3 G, for example. It must be streamlined to enter the atmosphere at all, of course.

Streamlining is just saying nothing will fall off the hull, and it won't burn up during a normal reentry. Nothing is said, or as far as I can see implied, about wings or other lift capability.

Streamlining is a necessary, but not sufficient, precondition for entering a world's atmosphere.

 

[AnotherDilbert]

Perhaps you should try it yourself by the rules as written.
As soon as the ship accelerates and flies off the ground it is in the 0.75g band (or are you insisting that planes can't fly). That

Try again, starting at zero velocity at the worlds surface.

 

[Captain_Ahab]

I see no reason a TL9 1g ship can not achieve a hypersonic speed of mach 32+.

what is cross sectional area?
Cd?
air density?
thrust available?

I'm afraid I don't see how it is possible except during an actual re-entry
and that's without considering stagnation temps or the energies that the ship absorbs through radiative transfer during hypersonic flight

 

[whartung]

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.

What's the G rating of an Air Raft for this discussion?

 

[AnotherDilbert]

What's the G rating of an Air Raft for this discussion?

Not explicitly defined, but presumably about 1.1 G.

According to Striker, 0.1 G over local gravity gives a speed of about 100 km/h.

 

[Grav_Moped]

I just enjoy the discussion, provided it is civil of course

This.

 

[Grav_Moped]

Perhaps you should try it yourself by the rules as written.
As soon as the ship accelerates and flies off the ground it is in the 0.75g band (or are you insisting that planes can't fly). That gives it a 25mm vector after subtracting for gravity.
Next turn it is in the 0.5g band, so its total vector is 75mm
Next turn it is in the 0.25g band, total vector 150mm and so on.
Not as fast to orbit as a 2g ship following a rocket trajectory (which is never vertical the whole trip)

Give LBB2 combat by the rules as written a try, including making planetary templates.

It works under the rules. Under real world physics? Not like that, anyhow. Not that it matters.

 

[Spinward Flow]

Perhaps you should try it yourself by the rules as written.

* ahem *

I DID.

I gave chapter, verse and mathmatical computations.
I showed my work while doing so.
I even did it exclusively using the book that the "standard type A Free Trader that is capable of 1G" appears in, rather than appealing to other sources (such as Striker).

As soon as the ship accelerates and flies off the ground

Explain how a ship can do that when it cannot get unstuck from the ground in the first place.

As I detailed (again) ... a 1G starship can do that on a Size: 7- world ... but cannot do so on a Size: 8+ world using the RAW that you're telling me to use.

 

[Condottiere]

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

Pure thrust plus lifting body would allow it to fly like a plane in an atmosphere, and then I would guess it's a question of thrust to actual weight ratio.

 

[mike wightman]

No, of course not. Neither am I saying 2000 tonne bricks are very good aerodynamically.
Aircraft works as usual, as detailed in Striker...



Striker is Traveller and CT, contemporary with LBB2'81, and the quoted rule applies specifically to spaceships.
View attachment 3544




No, but Striker says a ship must have a higher G-rating than local gravity: A 0.5 G ship would float happily in a local gravity of 0.3 G, for example. It must be streamlined to enter the atmosphere at all, of course.

Streamlining is just saying nothing will fall off the hull, and it won't burn up during a normal reentry. Nothing is said, or as far as I can see implied, about wings or other lift capability.

Streamlining is a necessary, but not sufficient, precondition for entering a world's atmosphere.

Then Striker is wrong.
A streamlined ship can fly.

 

[mike wightman]

Try again, starting at zero velocity at the worlds surface.

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

 

[mike wightman]

what is cross sectional area?
Cd?
air density?
thrust available?

I'm afraid I don't see how it is possible except during an actual re-entry
and that's without considering stagnation temps or the energies that the ship absorbs through radiative transfer during hypersonic flight

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.

 

[Grav_Moped]

Annnnd... we've looped around to the fun thing about Traveller: the rules as written don't describe the OTU -- but now, here's a spot where they don't even describe the game itself.

 

[mike wightman]

* ahem *

I DID.

I gave chapter, verse and mathmatical computations.
I showed my work while doing so.
I even did it exclusively using the book that the "standard type A Free Trader that is capable of 1G" appears in, rather than appealing to other sources (such as Striker).

Explain how a ship can do that when it cannot get unstuck from the ground in the first place.

As I detailed (again) ... a 1G starship can do that on a Size: 7- world ... but cannot do so on a Size: 8+ world using the RAW that you're telling me to use.

How does a plane take off?

 

[mike wightman]

Annnnd... we've looped around to the fun thing about Traveller: the rules as written don't describe the OTU -- but now, here's a spot where they don't even describe the rules themselves.

Oh this has been a discussion point for forty six years

On the one side you have the rocket crowd and on the other the spaceplane - the setting evidence is space plane from deckplans, artwork and starport layout (they have runways)

 

[Enoki]

what is cross sectional area?
Cd?
air density?
thrust available?

I'm afraid I don't see how it is possible except during an actual re-entry
and that's without considering stagnation temps or the energies that the ship absorbs through radiative transfer during hypersonic flight

Air / atmospheric density is an important issue here. Obviously heavier things can float in an ocean of water than can float in an ocean of air. The same can be said that things that float in the air on Earth might not float in the air on an Earth-like planet with half the atmosphere... So, the weight to volume ratio-- eg., the displacement--of the ship makes a difference here regardless of its drive capacity.

Thus, there's far more to this than just the drive capacity of the ship.

So, if the ship is streamlined, and even just a lifting body with some aerodynamic capacity, it could potentially move forward until it generates sufficient lift to offset gravity and then fly in the planet's atmosphere.

 

[Grav_Moped]

How does a plane take off?

With wheels on pavement. Which is problematic for some canon ship designs. But again, it's a game, and fiction to boot. It works if you want it to.

 

[Spinward Flow]

How does a plane take off?

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

Okay, here I go ...

How does a plane take off?

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 ...