Hull configurations - corrected

[DFW]

After reading a post by the author of this section of the MGT rules and, finding out that the editor altered them & inadvertently, made them illogical & unworkable; I rewrote for MTU to be closer to the original intent. Plus a couple rules of my own

For your use or, derision. :shock:

Configuration
A ship may have one of three hull configurations – standard (a wedge, cone, spheroid, needle or capsule), airframe (a wing, fuselage +wings or, other lifting body that has aeronautic control surfaces) or irregular (made up of several sections or shaped so as to not allow entry into an atmosphere at high speed, and incapable of maintaining its shape under gravity if landed).

A standard ship may land on any world where its Grav-Space M-Drive rating exceeds gravity. It is capable of VTOL and manoeuvre in all directions but, is not capable aerobatic type maneuvers. Most standard hulls under 700 tons are of monocoque construction. Standard hulls can be built with fuel scoops (at a cost of Kcr50 per 100 tons of ship), which allow the skimming of unrefined fuel from gas giants or the gathering of water from open lakes or oceans.

An irregular ship reduces the cost of its hull by 10%. It is completely non-aerodynamic and may only enter an atmosphere if moving slower than 200 kph and, is using a Grav-Space M-Drive with a rating twice that of the planet's gravity. (this is always a Very Difficult task). It cannot land nor, mount fuel scoops.

An airframe ship may enter atmosphere, land & take-off as a standard hull and has fuel scoops. But, in addition, it can land and take-off (with sufficient runways) on worlds with atmospheres of very thin or greater, where the gravity is up to 1 greater than its M-Drive rating. Operating in this manner requires that the ship obtain and maintain an air speed of at least 400, 500 & 600 kph in; standard, thin & very thin atmosphere's respectively. These ships can perform acrobatic combat maneuvers in atmosphere. An airframe ship increases the cost of the hull by 10% and requires 5% of the ship's tonnage for increased structural integrity. Flyer-1 or better is required in order for the pilot to take advantage of the aeronautic properties of the hull. An airframe may not be retrofitted; it must be designated at the time of construction.

 

[far-trader]

I like it. Obviously zombies have eaten my brain while I slept...

It's good, really. And I think I see where your Air/Raft tease might be headed.

One clarification. For the irregular configuration, no landing is understood and makes sense, but what about settling? An immersion supported "landing" in a water/liquid tank facility, or a cradled facility of specific support struts or repulsor field? Allowed? Worth adding as a clarification option?

Again, bravo on the additions to the edited/cut original intent.

 

[SSWarlock]

Concise clarity..I like it! Count your rewrite as being added to my Core Book inside back cover for future reference.

This does raise a couple of questions in my mind though. Is there any point in adding aerofins to airframe designs or irregular designs? And, in light of the rewrite, do they add their +2 DM bonus to Flyer checks as well as Pilot checks?

 

[rust]

Looks very good.

In my view ships with an irregular configuration should normally not be
allowed to land on water. Most of such ships will not be designed to be
balanced well enough to float in any acceptable orientation or to with-
stand the structural stress caused by a rough sea.

As for aerofins, I think they would be useful for standard configuration
and airframe configuration ships, a +2 for the pilot's skill can always be
welcome to counter negative modifiers for bad weather and thelike. In
the case of irregular configuration ships they would normally make not
much sense, because they could work only if the ship in question has
an at least remotely aerodynamic shape.

An idea I have borrowed for my settings from GURPS Spaceships is a
Soft Landing System, a combination of a heat shield, parachutes and a
set of rockets, which can be used to land any kind of ship in an emer-
gengy, but can only be used once and then has to be replaced.

 

[far-trader]

Looks very good.

In my view ships with an irregular configuration should normally not be
allowed to land on water. Most of such ships will not be designed to be
balanced well enough to float in any acceptable orientation or to with-
stand the structural stress caused by a rough sea.

Good points, though I was more thinking a landing facility rather than open water. That's worth a clarification.

Too often my designs, even irregular hulls, are reasonably balanced and bilaterally symmetrical. It's more habit than anything, and asymmetrical hulls are a pain for a number of practical reasons.

 

[DFW]

Hi guys, thanks for the comments/questions & kudo's.

I think that we could say: "irregular hulls can dock in purpose built cradles and water landing if non-dispersed structure (see MT def.) & symmetrically designed but, only on planets with not greater than 1 gravity."

Aerofins can be added to standard & airframe using HG rules to gain additional handling bonuses. Irregular hulls, no, as the airflow is too disrupted by the non-aerodynamic hull shape for such fins to be useful.

fartrader, yes this is the "flip side" grav tech to the air raft AG tech. I'm polishing & distilling the "science" behind both (surprisingly it involves dark matter) and I will have ready to post later this week. For the MGT universe it will unify, vehicle AG, space grav drive AND make some sense of J-space & J- drive. Keeping it MGT rules consistent.

 

[phavoc]

Nicely done. I have added in some comments below.

After reading a post by the author of this section of the MGT rules and, finding out that the editor altered them & inadvertently, made them illogical & unworkable; I rewrote for MTU to be closer to the original intent. Plus a couple rules of my own

For your use or, derision. :shock:

Configuration
A ship may have one of three hull configurations – standard (a wedge, cone, spheroid, needle or capsule), airframe (a wing, fuselage +wings or, other lifting body that has aeronautic control surfaces) or irregular (made up of several sections or shaped so as to not allow entry into an atmosphere at high speed, and incapable of maintaining its shape under gravity if landed).

A standard ship may land on any world where its Grav-Space M-Drive rating exceeds gravity. It is capable of VTOL and manoeuvre in all directions but, is not capable aerobatic type maneuvers. Most standard hulls under 700 tons are of monocoque construction. Standard hulls can be built with fuel scoops (at a cost of Kcr50 per 100 tons of ship), which allow the skimming of unrefined fuel from gas giants or the gathering of water from open lakes or oceans.

An irregular ship reduces the cost of its hull by 10%. It is completely non-aerodynamic and may only enter an atmosphere if moving slower than 200 kph and, is using a Grav-Space M-Drive with a rating twice that of the planet's gravity. (this is always a Very Difficult task). It cannot land nor, mount fuel scoops.

I agree that a ship of such a configuration would need to enter the atmosphere slowly, but I am wondering why you say the M-drive needs to be twice the planets gravity? Traveller gravitics really don't talk about mass (unlike GURPS). You either have anti-grav, or you don't. Now you can change the propulsion aspect, and have bigger thrusters to move you faster, but nothing I can recall talks about anti-grav in particular. So I would think that as long as you had anti-grav, you could enter an atmosphere. Now, depending on the type of atmo and the ensuing weather, some ships may not be able to do this, but that would be more dependent upon the referee I think, generating the necessary background for the ship to enter. In general it should be a bad idea to take a ship down into a turbulent atmosphere. As a rule of thumb, irregular ships would need to land in very gentle weather or else possibly suffer from the effects of the weather.

An airframe ship may enter atmosphere, land & take-off as a standard hull and has fuel scoops. But, in addition, it can land and take-off (with sufficient runways) on worlds with atmospheres of very thin or greater, where the gravity is up to 1 greater than its M-Drive rating. Operating in this manner requires that the ship obtain and maintain an air speed of at least 400, 500 & 600 kph in; standard, thin & very thin atmosphere's respectively. These ships can perform acrobatic combat maneuvers in atmosphere. An airframe ship increases the cost of the hull by 10% and requires 5% of the ship's tonnage for increased structural integrity. Flyer-1 or better is required in order for the pilot to take advantage of the aeronautic properties of the hull. An airframe may not be retrofitted; it must be designated at the time of construction.

Again, I think with anti-grav, ships are going to take off and land via VTOL like maneuvers, and then engage thrusters to move. In some startports they may "taxi" to departure zones, just to keep traffic sane in the area, kind of like helo's do today at airports. But once free of the traffic pattern they can maneuver to local airspace rules. But I agree that airframe craft should be able to perform like aircraft today. Though with a grav generator onboard, the acrobratics you could do would not be limited by aerodynamics like they are today.

 

[DFW]

I agree that a ship of such a configuration would need to enter the atmosphere slowly, but I am wondering why you say the M-drive needs to be twice the planets gravity? Traveller gravitics really don't talk about mass (unlike GURPS). You either have anti-grav, or you don't. Now you can change the propulsion aspect, and have bigger thrusters to move you faster, but nothing I can recall talks about anti-grav in particular. So I would think that as long as you had anti-grav, you could enter an atmosphere. Now, depending on the type of atmo and the ensuing weather, some ships may not be able to do this, but that would be more dependent upon the referee I think, generating the necessary background for the ship to enter. In general it should be a bad idea to take a ship down into a turbulent atmosphere. As a rule of thumb, irregular ships would need to land in very gentle weather or else possibly suffer from the effects of the weather.

According to the MGT rules, "irregular" ships cannot hold up their shape (hull integrity) under gravity. If you have 1 G grav drives and you want to land on a 1 G planet you have no additional maneuver power to move the ship. There are no "thrusters" in MGT other than the grav M-drive. So, it would need the additional G in drive to keep from having any sheer force on the hull.

Again, I think with anti-grav, ships are going to take off and land via VTOL like maneuvers, and then engage thrusters to move. In some startports they may "taxi" to departure zones, just to keep traffic sane in the area, kind of like helo's do today at airports. But once free of the traffic pattern they can maneuver to local airspace rules. But I agree that airframe craft should be able to perform like aircraft today. Though with a grav generator onboard, the acrobratics you could do would not be limited by aerodynamics like they are today.

There are no "thrusters" other than the grav M-drive unless you add additional reaction drives to your ship. As far as how nimble you Grav M-drives are; I'm using the MGT rule that non-lifting body Grav M-Drive ships are clumsy enough to have a penalty to fine control even in the thin upper atmosphere of a GG. As opposed to the airframe hulls using aeronautic control surfaces.

 

[phavoc]

I agree that a ship of such a configuration would need to enter the atmosphere slowly, but I am wondering why you say the M-drive needs to be twice the planets gravity? Traveller gravitics really don't talk about mass (unlike GURPS). You either have anti-grav, or you don't. Now you can change the propulsion aspect, and have bigger thrusters to move you faster, but nothing I can recall talks about anti-grav in particular. So I would think that as long as you had anti-grav, you could enter an atmosphere. Now, depending on the type of atmo and the ensuing weather, some ships may not be able to do this, but that would be more dependent upon the referee I think, generating the necessary background for the ship to enter. In general it should be a bad idea to take a ship down into a turbulent atmosphere. As a rule of thumb, irregular ships would need to land in very gentle weather or else possibly suffer from the effects of the weather.

According to the MGT rules, "irregular" ships cannot hold up their shape (hull integrity) under gravity. If you have 1 G grav drives and you want to land on a 1 G planet you have no additional maneuver power to move the ship. There are no "thrusters" in MGT other than the grav M-drive. So, it would need the additional G in drive to keep from having any sheer force on the hull.

Again, I think with anti-grav, ships are going to take off and land via VTOL like maneuvers, and then engage thrusters to move. In some startports they may "taxi" to departure zones, just to keep traffic sane in the area, kind of like helo's do today at airports. But once free of the traffic pattern they can maneuver to local airspace rules. But I agree that airframe craft should be able to perform like aircraft today. Though with a grav generator onboard, the acrobratics you could do would not be limited by aerodynamics like they are today.

There are no "thrusters" other than the grav M-drive unless you add additional reaction drives to your ship. As far as how nimble you Grav M-drives are; I'm using the MGT rule that non-lifting body Grav M-Drive ships are clumsy enough to have a penalty to fine control even in the thin upper atmosphere of a GG. As opposed to the airframe hulls using aeronautic control surfaces.

If a ship were to align itself to the gravity well in the same fashion it moves under thrust, it would retain its shape. I'm not a structural engineer, but if the ship was that delicate, it could never accelerate in space. It HAS TO have enough structural integrity in space to be able to maneuver. Ergo, it must be able to support itself in a gravity well if it treats the gravity in the same manner as it would acceleration.

As for thrusters not existing, I would say that is an oversight of the rules (like many other things). I grant you your point that Traveller does not talk about a ship having thrusters. However, it does talk about pre-grav spacecraft. It says nothing about those ships utilizing thrusters, but they must have some sort of auxillary maneuvering capabilities beyond their M-drives. We do kinda know this from reality today. The shuttle (and every other space craft) use thrusters for minor manuevers. Modern ships use thrusters (instead of tugs) to get into and out of docks. The fact that the rules have (another) oversight doesn't negate that they don't exist. They just were overlooked in the descriptions for ships because for the most part they aren't necessary for game play.

 

[DFW]

If a ship were to align itself to the gravity well in the same fashion it moves under thrust, it would retain its shape. I'm not a structural engineer, but if the ship was that delicate, it could never accelerate in space. It HAS TO have enough structural integrity in space to be able to maneuver. Ergo, it must be able to support itself in a gravity well if it treats the gravity in the same manner as it would acceleration.

Wind sheer and loading is not the same. When you ADD gravity to it, you are in trouble. In space you aren't using reaction thrust. So, there is no acceleration stress from that. When you change direction in space, you change the direction of free fall.

It says nothing about those ships utilizing thrusters, but they must have some sort of auxillary maneuvering capabilities beyond their M-drives. We do kinda know this from reality today. The shuttle (and every other space craft) use thrusters for minor manuevers. Modern ships use thrusters (instead of tugs) to get into and out of docks. The fact that the rules have (another) oversight doesn't negate that they don't exist. They just were overlooked in the descriptions for ships because for the most part they aren't necessary for game play.

You are confusing reaction drives with Grav drives. Grav causes a ship to "fall" in the direction needed. Less power and you get less G's. .001 in any direction that you want. No, it isn't an oversight in the rules. If you don't install a reaction drive, you don't have reaction thrusters.

 

[GypsyComet]

loading is not the same. When you ADD gravity to it, you are in trouble. In space you aren't using reaction thrust. So, there is no acceleration stress from that. When you change direction in space, you change the direction of free fall.

So you are using an "Inertia Bubble" model for MDrive, then? The drive acts on the entire hull?

 

[SSWarlock]

There was a discussion thread back in 2007 on the Citizens of the Imperium forum that went into some detail on the use of maneuver drives in gravity wells and gas giant skimming. It goes on for some length and does require a viewer to have a login (which is free) but there's some pretty interesting points made there.

Here's the link for anyone interested.

http://www.travellerrpg.com/CotI/Discuss/showthread.php?p=164034#poststop

 

[phavoc]

If a ship were to align itself to the gravity well in the same fashion it moves under thrust, it would retain its shape. I'm not a structural engineer, but if the ship was that delicate, it could never accelerate in space. It HAS TO have enough structural integrity in space to be able to maneuver. Ergo, it must be able to support itself in a gravity well if it treats the gravity in the same manner as it would acceleration.

Wind sheer and loading is not the same. When you ADD gravity to it, you are in trouble. In space you aren't using reaction thrust. So, there is no acceleration stress from that. When you change direction in space, you change the direction of free fall.

It says nothing about those ships utilizing thrusters, but they must have some sort of auxillary maneuvering capabilities beyond their M-drives. We do kinda know this from reality today. The shuttle (and every other space craft) use thrusters for minor manuevers. Modern ships use thrusters (instead of tugs) to get into and out of docks. The fact that the rules have (another) oversight doesn't negate that they don't exist. They just were overlooked in the descriptions for ships because for the most part they aren't necessary for game play.

You are confusing reaction drives with Grav drives. Grav causes a ship to "fall" in the direction needed. Less power and you get less G's. .001 in any direction that you want. No, it isn't an oversight in the rules. If you don't install a reaction drive, you don't have reaction thrusters.

I'm aware of torsional forces. That's why I mentioned weather in my post. in calm weather the wind is of no factor. These are not delicate ships. If their hulls can shrug off 120mm rounds and take maneuvering in space, they can take a 10knot wind. I didn't say it wouldn't be a difficult maneuver, but it should not be treated as impossible. Bringing the ISS down? Yeah, that's a tough one. But a trav ship would be doable under the right circumstances. Or at least should be.

Trav grav drives still accelerate and retain velocity. They act and sound like reaction based drives to me. Thrusters make sense as they are simple and proven. In your other post about antigrav tech you make mention of thrusters. Plus, I never specified that they have to be reaction style. Maybe uber hydrazine or maybe they are grav thrusters.

 

[phavoc]

If a ship were to align itself to the gravity well in the same fashion it moves under thrust, it would retain its shape. I'm not a structural engineer, but if the ship was that delicate, it could never accelerate in space. It HAS TO have enough structural integrity in space to be able to maneuver. Ergo, it must be able to support itself in a gravity well if it treats the gravity in the same manner as it would acceleration.

Wind sheer and loading is not the same. When you ADD gravity to it, you are in trouble. In space you aren't using reaction thrust. So, there is no acceleration stress from that. When you change direction in space, you change the direction of free fall.

It says nothing about those ships utilizing thrusters, but they must have some sort of auxillary maneuvering capabilities beyond their M-drives. We do kinda know this from reality today. The shuttle (and every other space craft) use thrusters for minor manuevers. Modern ships use thrusters (instead of tugs) to get into and out of docks. The fact that the rules have (another) oversight doesn't negate that they don't exist. They just were overlooked in the descriptions for ships because for the most part they aren't necessary for game play.

You are confusing reaction drives with Grav drives. Grav causes a ship to "fall" in the direction needed. Less power and you get less G's. .001 in any direction that you want. No, it isn't an oversight in the rules. If you don't install a reaction drive, you don't have reaction thrusters.

I'm aware of torsional forces. That's why I mentioned weather in my post. in calm weather the wind is of no factor. These are not delicate ships. If their hulls can shrug off 120mm rounds and take maneuvering in space, they can take a 10knot wind. I didn't say it wouldn't be a difficult maneuver, but it should not be treated as impossible. Bringing the ISS down? Yeah, that's a tough one. But a trav ship would be doable under the right circumstances. Or at least should be.

Trav grav drives still accelerate and retain velocity. They act and sound like reaction based drives to me. Thrusters make sense as they are simple and proven. In your other post about antigrav tech you make mention of thrusters. Plus, I never specified that they have to be reaction style. Maybe uber hydrazine or maybe they are grav thrusters.

 

[DFW]

So you are using an "Inertia Bubble" model for MDrive, then? The drive acts on the entire hull?

I elaborate here: http://www.mongoosepublishing.com/phpBB2/viewtopic.php?t=48084

 

[phavoc]

If a ship were to align itself to the gravity well in the same fashion it moves under thrust, it would retain its shape. I'm not a structural engineer, but if the ship was that delicate, it could never accelerate in space. It HAS TO have enough structural integrity in space to be able to maneuver. Ergo, it must be able to support itself in a gravity well if it treats the gravity in the same manner as it would acceleration.

Wind sheer and loading is not the same. When you ADD gravity to it, you are in trouble. In space you aren't using reaction thrust. So, there is no acceleration stress from that. When you change direction in space, you change the direction of free fall.

It says nothing about those ships utilizing thrusters, but they must have some sort of auxillary maneuvering capabilities beyond their M-drives. We do kinda know this from reality today. The shuttle (and every other space craft) use thrusters for minor manuevers. Modern ships use thrusters (instead of tugs) to get into and out of docks. The fact that the rules have (another) oversight doesn't negate that they don't exist. They just were overlooked in the descriptions for ships because for the most part they aren't necessary for game play.

You are confusing reaction drives with Grav drives. Grav causes a ship to "fall" in the direction needed. Less power and you get less G's. .001 in any direction that you want. No, it isn't an oversight in the rules. If you don't install a reaction drive, you don't have reaction thrusters.

I'm aware of torsional forces. That's why I mentioned weather in my post. in calm weather the wind is of no factor. These are not delicate ships. If their hulls can shrug off 120mm rounds and take maneuvering in space, they can take a 10knot wind. I didn't say it wouldn't be a difficult maneuver, but it should not be treated as impossible. Bringing the ISS down? Yeah, that's a tough one. But a trav ship would be doable under the right circumstances. Or at least should be.

Trav grav drives still accelerate and retain velocity. They act and sound like reaction based drives to me. Thrusters make sense as they are simple and proven. In your other post about antigrav tech you make mention of thrusters. Plus, I never specified that they have to be reaction style. Maybe uber hydrazine or maybe they are grav thrusters.

 

[DFW]

Trav grav drives still accelerate and retain velocity. They act and sound like reaction based drives to me.

Free fall in a grav well is not the same as reaction based thrust from rockets at all. I'm sorry, I don't have the bandwidth to get into the physics & math here.

 

[phavoc]

Trav grav drives still accelerate and retain velocity. They act and sound like reaction based drives to me.

Free fall in a grav well is not the same as reaction based thrust from rockets at all. I'm sorry, I don't have the bandwidth to get into the physics & math here.

Lol. Me either. Tis ok if you wanna pick and choose your responses. Clearly I'm wasting my time trying to have a discussion with you.

 

[DFW]

Clearly I'm wasting my time trying to have a discussion with you.

I just don't know how to dig deeper into the science in without spending a ton of time. That's what it would take to keep from going in circles with you.

 

[Jak Nazryth]

Would non-standard shapes still fall into "standard" hulls?
For instance, the 200 ton far trader; is it a needle, cone, wedge? Kinda looks like a simi-streamlined shoebox.
(In the past I REALLY bend the rules by calling this a close structure with streamlining. The streamlining only allows a close structure to behave like a standard hull in the atmosphere and not a "true" streamlined hull)
If you look at the core book ship write-ups they simply say "Streamlined" "Dispersed" or the spot is left blank as in the yacht and lab ship. In a perfect world (yeah right) there would be a line on the MGT ship description saying "standard-wedge" or "streamlined-wedge" etc...

I have several designs that don't fall into the strict "shape" categories as described in the core rules. GURPS and T20 (I think) allow for non-standard designs that are still atmosphere capable, but you just don't get a cost break when not using one of the standard shapes, even though they can be atmosphere capable.
I have several designs that don't fall into the specific shapes but as a design factor per game mechanics, they are still classified as "Standard" ie... streamlined "enough" to enter atmospheres etc...

For instance, what you classify a cube? Not dispersed.... not streamlined... standard? Or use the HG rules and call it "Close structure"?

Take a rectangular slab... "shoebox" and give a curved "rounded off" leading edge and it is streamlined enough to enter an atmosphere. What is its hull type?

Or is this simply being to picky? 8)