CordwainerFish
Emperor Mongoose
Then I would recommend doing that flyby at well below Mach 1.
Search and Rescue
- Thread starter Tawny Owl
- Start date
The atmosphere rules for streamlined/etc were written when Traveller thought ships used reaction drives. They are conceptually the same now as in the 77 edition. Lifters weren't a thing then. They are now. Like a lot of things in Traveller, they added technology and didn't change the fiction/rules to reflect it.
Unstreamlined ships and partially streamlined ships are bad at "flying" in atmosphere, as it travelling around from place to place. If you accept that every ship has lifters, there's nothing stopping the ship from slowly sinking to the ground from orbit. If you want it zipping around like an aircraft, that's a different story.
But people want the star wars take off: rise up slightly and zoom off. That's a streamlined ship.
Unstreamlined ships and partially streamlined ships are bad at "flying" in atmosphere, as it travelling around from place to place. If you accept that every ship has lifters, there's nothing stopping the ship from slowly sinking to the ground from orbit. If you want it zipping around like an aircraft, that's a different story.
But people want the star wars take off: rise up slightly and zoom off. That's a streamlined ship.
CordwainerFish
Emperor Mongoose
Never mind that the Millennium Falcon has about as much lifting area as a crumpled piece of office paper.
George Lucas: patient zero of the Rule of Cool.
Condottiere
Emperor Mongoose
Not impossible to simulate - you just need the correct components to install onboard.
Outside supposed manoeuvre drive vectoring, you could install a second manoeuvre drive that's positioned to direct thrust downwards, assuming a bellylander, sufficient to neutralize the local gravity field.
Outside supposed manoeuvre drive vectoring, you could install a second manoeuvre drive that's positioned to direct thrust downwards, assuming a bellylander, sufficient to neutralize the local gravity field.
shirgall
Cosmic Mongoose
"Here's goes nothing" is the motto of the pilots of my players... I think they also use "Don't tell me the odds".
CordwainerFish
Emperor Mongoose
The national anthem of the Solomani Confederation? "Y'all Hold My Beer and Watch This".
And the CRB supports that for semi-streamlined hulls. It's mostly the weather in a dense atmosphere that's going to be making it a little harder than in a streamlined hull (i.e. a higher chance of more and more severe required Pilot checks).
The basic elements of flying are lift, drag, thrust and weight. Counter-grav eliminates the need for lift, drag and weight (in most cases, though the rules don't really talk about mass, just displacement... which is 'nother whole thread). Thrust offsets other forces, and when you take them out then your thrust is really the velocity you can (safely) maintain unless you are desperate. Things like atmospheric density and conditions will affect your speed and handling.
A non-aerodynamic ship that is structurally sound can land. Period. A ship that is more aerodynamic can accelerate faster with less buffeting and less issues with control. However even ships that are boxed shaped or spherical can easily maneuver and land - so long as they are reasonable about their flight profile and speed. A stately 200 kts (230mph) is easily doable with the magical engines of Traveller. It's not so fast that the non-streamlined ships would have overly large amounts of buffeting ascending or descending. Some ships would quickly encounter buffeting and resistance at low subsonic speeds, and while you can apply more thrust, the paradox is that fluid dynamics of the air states it becomes harder and harder to go faster. That's just normal aerodynamical laws.
Because conter-grav ignores orbital mechanic laws, you can travel straight up at 200 kts and in LEO in under an hour (assumes that as the ship gets higher it's thrust will increase as atmospheric density lessens.
Any craft, even with anti-grav, is still subject to mother nature - or at least that's my understanding. It's mass and shape would affect how much effect wind-borne forces would come into play.
A non-aerodynamic ship that is structurally sound can land. Period. A ship that is more aerodynamic can accelerate faster with less buffeting and less issues with control. However even ships that are boxed shaped or spherical can easily maneuver and land - so long as they are reasonable about their flight profile and speed. A stately 200 kts (230mph) is easily doable with the magical engines of Traveller. It's not so fast that the non-streamlined ships would have overly large amounts of buffeting ascending or descending. Some ships would quickly encounter buffeting and resistance at low subsonic speeds, and while you can apply more thrust, the paradox is that fluid dynamics of the air states it becomes harder and harder to go faster. That's just normal aerodynamical laws.
Because conter-grav ignores orbital mechanic laws, you can travel straight up at 200 kts and in LEO in under an hour (assumes that as the ship gets higher it's thrust will increase as atmospheric density lessens.
Any craft, even with anti-grav, is still subject to mother nature - or at least that's my understanding. It's mass and shape would affect how much effect wind-borne forces would come into play.
Condottiere
Emperor Mongoose
I rather suspect it depends on how much you mass in relationship to your volume, and how much you can counter that gust of wind.
Tawny Owl
Mongoose
Thanks Phavoc, this is a really helpful explanation for me. Maybe this kind of clarification could be added to the rules somewhere.
CordwainerFish
Emperor Mongoose
Hm, I'd expect surface area over mass to control - less mass, more acceleration per force. But the pilot in my family never flew anything larger than a puddle jumper, I think, and besides has been dead too long to ask.
It's both - essentially density. A more massive object takes more force to move, but a larger object of the same mass will have more force applied to it by wind force. You're correct in terms of a given point force (such as from a collision or a rocket), but the force that wind applies to an object scales up with surface area. Even with aerodynamic objects, wind from an unexpected direction can cause issues, for example a gust pushing down on the wings.
I was just suggesting that a helicopter is closer to a Traveller grav vehicle in this respect than an airship. Heavier than air, can hover. Most likely they're a bit less dense, but far closer than a blimp.
I was just suggesting that a helicopter is closer to a Traveller grav vehicle in this respect than an airship. Heavier than air, can hover. Most likely they're a bit less dense, but far closer than a blimp.
Condottiere
Emperor Mongoose
The fuel tanks could be filled with hydrogen.
Possibly, forty one percent of volume.
Possibly, forty one percent of volume.
CordwainerFish
Emperor Mongoose
Surface area goes by the square of the size. Mass goes by the cube.
The Helicopter also points out the other consideration. While 1G is enough to counteract gravity, if you want to move laterally you need to divert some of it. Much of that manoeuvring could be done in orbit, but if you are not streamlined you are spending a lot of the descent time directly over the spaceport. This will likely impact other traffic.
I also don't like the way that if you are un-streamlined you are penalised for taking your time. Whilst you get a bonus to your pilot check, as it requires a check every minute you will require far more of them. Indeed you might be better served by rushing, thrusting toward the planet and whilst taking a -2 on the roll, possibly reduce the number of rolls by several factors.
Each failed check inflicts a fixed amount of damage that is proportionally less the larger the ship (which seems counter intuitive). Armour does not protect (which seems illogical if it is the effects of heat and buffeting). This is not an effect of storms or other atmospheric effects since it always happens.
According to the rules on CRB p152
Landing at a starport requires a Routine (6+) Pilot check (1D x 10 seconds) but most pilots will take 1D minutes to perform a landing and gain DM+2 on the task.
I am ignoring the ongoing damage effects of atmosphere on an un-streamlined ship descending under control. An un-streamlined ship cannot descend under control if its thrust does not at least equal the gravity of the planet. I am using the DM-4 to piloting checks on the landing and any manoeuvres. This modifier also applies to the checks to request landing permission as starports have extra checks and procedures to apply.
Streamlined ships can land on planets where the gravity exceeds their thrust with a negative DM to the landing check equal to the difference in G's rounded up. Partially streamlined ships double any penalty.
Any ship descending out of control is handled on a case by case basis, but large ships may suffer more than small ones as they will be subject to greater shearing and torsion forces. Generally this is either a plot device or a potentially campaign ending event, so uncontrolled descent should be handled very carefully.
I also don't like the way that if you are un-streamlined you are penalised for taking your time. Whilst you get a bonus to your pilot check, as it requires a check every minute you will require far more of them. Indeed you might be better served by rushing, thrusting toward the planet and whilst taking a -2 on the roll, possibly reduce the number of rolls by several factors.
Each failed check inflicts a fixed amount of damage that is proportionally less the larger the ship (which seems counter intuitive). Armour does not protect (which seems illogical if it is the effects of heat and buffeting). This is not an effect of storms or other atmospheric effects since it always happens.
According to the rules on CRB p152
Landing at a starport requires a Routine (6+) Pilot check (1D x 10 seconds) but most pilots will take 1D minutes to perform a landing and gain DM+2 on the task.
I am ignoring the ongoing damage effects of atmosphere on an un-streamlined ship descending under control. An un-streamlined ship cannot descend under control if its thrust does not at least equal the gravity of the planet. I am using the DM-4 to piloting checks on the landing and any manoeuvres. This modifier also applies to the checks to request landing permission as starports have extra checks and procedures to apply.
Streamlined ships can land on planets where the gravity exceeds their thrust with a negative DM to the landing check equal to the difference in G's rounded up. Partially streamlined ships double any penalty.
Any ship descending out of control is handled on a case by case basis, but large ships may suffer more than small ones as they will be subject to greater shearing and torsion forces. Generally this is either a plot device or a potentially campaign ending event, so uncontrolled descent should be handled very carefully.
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I don't know that any of these (airship, helo or aircraft) are good examples. There are a few factors here:
1) starships don't require their hulls to provide lift, thus their hulls are less susceptible since the lifting surfaces are so different.
2) starships are far more massive than any helo or aircraft, let alone a LTA craft. Mass will matter, though mother nature can get to the point where her actions will overcome a great deal of mass - she has far more energy at her disposal when she's really angry.
3) the biggest factor is we have no clue how anti-grav would work. Does it make a starship like an LTA, where it's mass is fully negated? Or does it just cheat physics and retain mass but ignores gravity? Two entirely different things that greatly affect the discussion.
For the most part, as I see it at least, crosswinds less than say 100kph would just be ignored by any starship attempting to land - they are just too heavy and so long as it's just landing (an important distinction), it would be considered a nominal effort by any qualified pilot. Now, if the landing is also attempting to say mate with an airlock or any sort of cradle, then I think you can start factoring in wind as an issue. That sort of delicate maneuvering could definitely be needed to be offset. Could anti-grav be adjusted? I dunno, I see it more as lift than thrust, and since things like tractors and repulsors no longer exist in MGT Traveller, I don't think it's fair for a starship antigrav field to dip into this arena.
We do know that some craft utilize grav for both lift and directional forces, and arguably the M-drive plates do something similar. Not enough is really explained about the physics (I don't have new SOM, so if it is in there, I'm ignorant of it) to fairly argue one way or another.
<<OFF TOPIC DRIFT >>
But, in general, the tech is gonna be there, and it's gonna be taken advantage of because it's such a massive leap over what we have today. It's the same reasoning that any planet is going to spend whatever shekels is required in order to import grav-enabled craft to say service satellites or get to orbit rather than build a rocket because that would be stupid when you have technology available to skip that. ONLY if it is so rare or expensive to preclude even getting it would you not have it.
Think of it this way - if the US had access to a single 95ton shuttle, it would overnight scrap every rocket system in service. ONE shuttle would wipe out a $30billion dollar industry overnight.
1) starships don't require their hulls to provide lift, thus their hulls are less susceptible since the lifting surfaces are so different.
2) starships are far more massive than any helo or aircraft, let alone a LTA craft. Mass will matter, though mother nature can get to the point where her actions will overcome a great deal of mass - she has far more energy at her disposal when she's really angry.
3) the biggest factor is we have no clue how anti-grav would work. Does it make a starship like an LTA, where it's mass is fully negated? Or does it just cheat physics and retain mass but ignores gravity? Two entirely different things that greatly affect the discussion.
For the most part, as I see it at least, crosswinds less than say 100kph would just be ignored by any starship attempting to land - they are just too heavy and so long as it's just landing (an important distinction), it would be considered a nominal effort by any qualified pilot. Now, if the landing is also attempting to say mate with an airlock or any sort of cradle, then I think you can start factoring in wind as an issue. That sort of delicate maneuvering could definitely be needed to be offset. Could anti-grav be adjusted? I dunno, I see it more as lift than thrust, and since things like tractors and repulsors no longer exist in MGT Traveller, I don't think it's fair for a starship antigrav field to dip into this arena.
We do know that some craft utilize grav for both lift and directional forces, and arguably the M-drive plates do something similar. Not enough is really explained about the physics (I don't have new SOM, so if it is in there, I'm ignorant of it) to fairly argue one way or another.
<<OFF TOPIC DRIFT >>
But, in general, the tech is gonna be there, and it's gonna be taken advantage of because it's such a massive leap over what we have today. It's the same reasoning that any planet is going to spend whatever shekels is required in order to import grav-enabled craft to say service satellites or get to orbit rather than build a rocket because that would be stupid when you have technology available to skip that. ONLY if it is so rare or expensive to preclude even getting it would you not have it.
Think of it this way - if the US had access to a single 95ton shuttle, it would overnight scrap every rocket system in service. ONE shuttle would wipe out a $30billion dollar industry overnight.
This is where things can get a little funky. In theory, a 1G ship would not be able to overcome gravity and LIFT on a 1.5G world. That's because starships cannot take off and generate lift like a normal aircraft does. Or, using the helo example above, it would be too heavy to lift off the ground using it's main rotor for lift.
Let's say the planetary environment is 1.1G, and the ship is a 1G ship. Would your anti-grav system be able to generate 10% overage to give you a minimum ability to lift off the ground? Perhaps (maybe the system allows you to pump more power into it to generate more lift). Assuming you could generate enough lift to get off the ground, you would be able to use your engines to begin accelerating parallel to the ground at a slight upward angle to generate lateral thrust. Since M-drives have essentially unlimited fuel, over time you could generate enough horizontal speed to gain orbit. It's the same principle a rocket uses, except they have to do it at a much faster rate due to fuel limitations. Rockets go 'down range' from their launch because if they went straight up they wouldn't have enough angular velocity to make orbit. Prime example is what Bezos Blue Origin does - it goes straight up and comes straight down, even if it does get to vacuum.
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