Control surfaces used by Trav spacecraft in atmosphere
- Thread starter F33D
- Start date
Greylond said:
No. You'd just go around it. Why fly through it when you don't need to????
BTW, do you know the effect of flying a winged craft through winds like that and the negative effects of having lifting surfaces vs. NOT having them?
Did you also know that a bullet shaped ship in MGT is NOT streamlined hull. BUT, it would be easier to handle under high winds than a streamlined (MGT def) ship?
As F33D says, if you have a true unlimited delta-V anti-gravity drives, you can simply slow your ship down to roughly the speed of the air column over where you want to land and then descend towards the surface. Today's spacecraft have to use friction to slow themselves down since they don't have enough delta-V.
An aerodynamic ship would have a much easier time since it could always choose to aerobrake back into the atmosphere, but less maneuverable ships would land a lot like a modern lunar lander, only they'd have to start a few hundred kilometers up instead of nearly on the surface.
Obviously, on Earth there are high altitude winds that would make a "Straight down" landing tricky, but it's certainly easier to control than a hypersonic reentry. (The forces in a hypersonic reentry are many times a simple 1g or 2g drive's capabilities. I hope your inertial compensators can handle it....) One might imagine that a streamlined ship would have less trouble with this sort of thing, in the same way that a boat with a keel has an easier time holding course, but that's supposition on my part.
My suspicion is that most ships, streamlined or otherwise, will not bother entering orbit, but will "drop" onto the downport. They will use their drives to control their rate of descent and course, resorting to "wings and flaps" only when speed is important, or if their drives can't handle the local G-field. One version of Traveller had M-drives use up fuel, which made aerodynamics relevant, but MgT doesn't do that by default.
I suppose one could decide that a ship can't land on a world with a higher G rating than the ship's drives can produce unless it can use aerodyamic lift to make up the difference. That would make sense of the Subbie's design....
An aerodynamic ship would have a much easier time since it could always choose to aerobrake back into the atmosphere, but less maneuverable ships would land a lot like a modern lunar lander, only they'd have to start a few hundred kilometers up instead of nearly on the surface.
Obviously, on Earth there are high altitude winds that would make a "Straight down" landing tricky, but it's certainly easier to control than a hypersonic reentry. (The forces in a hypersonic reentry are many times a simple 1g or 2g drive's capabilities. I hope your inertial compensators can handle it....) One might imagine that a streamlined ship would have less trouble with this sort of thing, in the same way that a boat with a keel has an easier time holding course, but that's supposition on my part.
My suspicion is that most ships, streamlined or otherwise, will not bother entering orbit, but will "drop" onto the downport. They will use their drives to control their rate of descent and course, resorting to "wings and flaps" only when speed is important, or if their drives can't handle the local G-field. One version of Traveller had M-drives use up fuel, which made aerodynamics relevant, but MgT doesn't do that by default.
I suppose one could decide that a ship can't land on a world with a higher G rating than the ship's drives can produce unless it can use aerodyamic lift to make up the difference. That would make sense of the Subbie's design....
You don't always get the choice?F33D said:
Yes, and I understand that a flying brick that is NOT designed to fly in atmo is going to have a much worse time
I honestly don't think you understand the definition of the Game Mechanic, not a Real World Term, but the Game Mechanic. In Traveller, a hull is that is called "Streamlined" is meant to be able to fly in atmo. Anything else is NOT designed to be flown in atmo, but in MgT it can be at a - DM.
Ultimately, it depends.
A grav belt can reach orbit - which it does by floating straight upwards and downwards at really-not-very-many metres per second.
A grav-drive spacecraft can do the same thing. So can a grav-equipped brick, and (in extreme cases) a grav-equipped city.
What is not going to work is manouvring at speed. Which you may wish to do if...say...someone is shooting at you, or there is a massive storm formation (in which case, why are you trying to land, but hey, players are notred for doing stupid stuff). Ultimately, nothing stops you accellerating at whatever the resultant of X G in a direction of your choice plus the planet's gravity is, but this is just demonstrating the oft-quoted principle that if you put enough engine power behind a brick, it will fly. And manouvre, and land. As long as you can do it slowly, and carefully.
Something wishing to demonstrate actual manouvrability needs control surfaces. These can be conventional (actual swivelling bits of the ship like a modern plane), deformational (moving parts inside a flexible skin or some sort of piezo-style flexible skin (fine for low speed work but flexible skins on 3G system ships is asking for the nth debate on interplanetary dust), or consist of shaped airflow - using engine bleed to make 'fake' lifting surfaces dates back to the Blackburn Buccanneer fighter-bomber in the 60's. What F33D is talking about is a more sophisticated application - allowing you to make control surfaces rather than just a bigger 'wing', but the principle (from the pilot's perspective, at least) is the same. Airflow-based thrust vectoring is another one - albeit not relevant to an aircraft without a 'jet' output of some sort.
As ever, the universal rule on skill checks applies:
Core Rulebook said:
99.99999% of takeoffs and landings in the Imperium - even with a standard, unstreamlined ship, will not involve time pressure, danger or be at all interesting. But that's because they will not be made by Traveller player characters whose beat-up, unmaintained ship is being flown through a thunderstorm by the unskilled steward with a badly wounded character desperately needing surgery and a wing of really, really angry Aslan gunships chasing them. Under similar circumstances, which happen to Traveller PCs more often than most would care to admit, a -2DM for 'proper' manouvres is worth every credit of the surcharge on the hull!
F33D said:Greylond said:Not the way that you've obviously house ruled it.
The only thing I've house ruled is getting rid of highly illogical bits.
That's my point, you house rule away the -2 DM for non-streamlined hulls and then claim that Streamlining a Hull gives no advantage. It gives you no advantage because you house ruled the advantage away...
Greylond said:F33D said:Greylond said:Not the way that you've obviously house ruled it.
The only thing I've house ruled is getting rid of highly illogical bits.
That's my point, you house rule away the -2 DM for non-streamlined hulls and then claim that Streamlining a Hull gives no advantage. It gives you no advantage because you house ruled the advantage away...
Nope. reread my posts. I give that advantages of a streamlined hull. I get rid of the -2 unless trying maneuvers that require lifting surfaces. Where else would the -2 apply?
F33D said:Greylond said:Not the way that you've obviously house ruled it.
The only thing I've house ruled is getting rid of highly illogical bits.
Then you don't have Grav Drives at all in your game?
As a fictional piece of technology, Grav Drives, for the purposes of Traveller, have certain design/performance limitations. One of the limitations is that any Grav Vehicle operating in an atmosphere requires that the game terms as "Streamlined"(whatever that entails) or suffer penalties to flying it.
IMO, comparing Real World technology craft to Traveller SciFi craft at certain points and claim "Logic" is a fallacy. The Game Mechanics define how the Tech works. Change the game mechanics IYTU as you wish but you aren't using "Logic," you are changing how a fictional piece of technology works.
As far as modern Science knows Grav Drives as presented is impossible so if you are going to apply Real World Logic to it, then you are going to have to completely disallow it...
Captain Jonah
Mongoose
locarno24 said:
You missed one.
When you want to worry the players, make them nervous, bring the fear and horror to the game....
make a sensor check, thats fine you don't think there is anything there.
6 minutes later
make a sensor check, yep there doesn't seem to be anything there.
6 minutes later
make a sensor check, OK you are fairly certain the area is clear.
6 minutes later :twisted:
Well, I seem to have a slightly different approach. In my settings
there is no -2 modifier for the atmospheric operations of any non-
streamlined vehicles, because under normal conditions streamli-
ned and non-streamlined vehicles can perform all routine maneu-
vers equally well. However, I do use a +2 modifier for streamlined
vehicles under difficult conditions, where their ability to maneuver
faster and more precisely is likely to give them an advantage.
For example, if both the streamlined ship A and the non-streamli-
ned ship B want to land at my setting's Thalassa Downport on a
clear day, I do not see a need for a penalty for ship B. But if these
two ships want to land on an unusually rainy and windy day, the
streamlined ship A gets a little bonus.
there is no -2 modifier for the atmospheric operations of any non-
streamlined vehicles, because under normal conditions streamli-
ned and non-streamlined vehicles can perform all routine maneu-
vers equally well. However, I do use a +2 modifier for streamlined
vehicles under difficult conditions, where their ability to maneuver
faster and more precisely is likely to give them an advantage.
For example, if both the streamlined ship A and the non-streamli-
ned ship B want to land at my setting's Thalassa Downport on a
clear day, I do not see a need for a penalty for ship B. But if these
two ships want to land on an unusually rainy and windy day, the
streamlined ship A gets a little bonus.
That's covered above. Success or failure is interesting. It doesn't specify who it's interesting to.
It's amazing how interesting an empty volume of space can be, especially if you have a GM's screen and some dice of your own.
"Did you just roll an opposed check there?"
"....Maybe. You don't see anything."
"Aaaaaaaaaaaaaaaaaaagh!"
WRT where the -2 should apply: my response is that as far as the fake science goes, I agree with F33D - clearly a -2 will only apply to checks where it matters that you aren't streamlined; i.e. where you're either trying to manouvre violently like an aeroplane or you're in a serious crosswind/storm/whatever. Any other time it won't matter. My response to that - which agrees more with Greylond - is those are the only times I'd normally botherto make people make pilot tests anyway.
