Planetary Flight: Unit settings

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pheonixstorm
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Planetary Flight: Unit settings

Post by pheonixstorm »

I think I have brought this up before, not sure though...

So, with planetary flight getting closer and closer we now should look at what to do about the various units in the game.

* Should all units be able to handle atmospheric flight or only a select number?
* Should we set a new field in units.csv? A boolean yes/no?
* How do we handle landings? Dock method or manual landings.
* How do we handle launching/takeoff?

Add more if you can think of anything
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Hicks
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Re: Planetary Flight: Unit settings

Post by Hicks »

First thing i believe we should do is add in gravity and some sort of atmosphere, things to keep you moving with planets. Been playing with planetary flight, and its hard trying to stay with the planet, as it rotates and moves.

Not all unit can handle atmospheric flight, mainly because they have the thrust to get off a planets surface.
Since fuel is used only when thrust is applied, some ships will be using a lot of fuel to get out of the atmosphere, as they will be constatly fighting against gravity.
I personally would like to see manual landings, but i do love flight sims. We be interesting to be able to deploy landing pads, and you can then touch down on a surface as long as you are going less then a ceratin speed, 2 or 3 m/s maybe.

Takeoff could be done a few ways. The units.csv have a column for top acceleration, so you could leave the hanger, be in the flight screen on the surface, then hit the up thruster(might need a key for it) and lift off, start to rotate to face up then hit the main thrusters.

For takeoff and landing, if you want to try and attach wheels to some spacecraft, you can try to add some basic flight dynamics and have them land like a real aircraft would. May be useful for craft with little up thrust but heaps of forward thrust, eg fighters or something.

For docking you might need to have little pads the player needs to be on and stopped moving in order to enter the station/planet/base
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Re: Planetary Flight: Unit settings

Post by klauss »

pheonixstorm wrote: * Should all units be able to handle atmospheric flight or only a select number?
I think all units should be able to attempt it.
pheonixstorm wrote: * Should we set a new field in units.csv? A boolean yes/no?
No, I'd go for air resistance and friction numbers. Atmo-capable ships should be aerodynamic enough that air resistance doesn't build up too fast for shields/armor to cope with it.

Air resistance would be the air resistance coefficient, the ratio of speed vs opposite force.

Friction numbers would be a way to include artificial items like shields into the mix, and would be the ratio of speed vs damage.

Now, aerodynamic ships would receive damage slowly enough that shields would be able to survive landing, while non-aerodynamic ships would simply burn up.
pheonixstorm wrote: * How do we handle landings? Dock method or manual landings.
I'd go for dock method, but you can place the docking markers on the ground, and make people fly there. You could also place more docking markers, meaning more than one base per planet. Would have to think about this a bit. Maybe as subunits...
pheonixstorm wrote: * How do we handle launching/takeoff?
In an ideal case, you'd start hovering over the ground and would have to gain escape velocity. In reality, it's probable that VS won't spawn you at the right position for this to happen, or maybe regaining escape velocity is too much for current enginges. Would have to test.


Wheels are not necessary IMO. We can expect repulsor beam-laden landing platforms.
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travists
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Re: Planetary Flight: Unit settings

Post by travists »

Klauss is right, but shields can take a huge amount of damage, as such craft that today could not handle an atmospheric landing may be able to with shields. The other question this raises is how do weapons and shields work under atmospheric conditions? Many of the weapons described physics allow, but only in a vacuum. I'm wondering if stars too should have a field effect region. Outer atmos has high radiation and heat, the closer in you get the hotter it is. Special thruster and shield configurations allow you to hide in a stars corona and strike from cover. Many ships can handle atmospheric landing, but how do we handle drag and other things from trying to maneuver in an atmosphere? How do hulls respond to explosions when they no longer have as much pressure to resist them?

All craft can try to do anything, but there are three ratings that I see:
  • Space rated only: any attempt to land will likely end badly.
  • Reentry capable: you can land without issue, but if attacked your best bet is to nose up and run for space.
  • Full atmospheric rating: It may preform differently, but it can fight in an atmosphere just fine.
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Re: Planetary Flight: Unit settings

Post by Deus Siddis »

A couple things:

So many ships in VS currently have such incredible thrusters that they have as much as 30g acceleration. Add to this that the atmospheres inherent around all high gravity worlds provides ships with limitless reaction mass, in other words "Fuel" as the HUD calls it. Thus aerodynamics only limits how fast these ships can go, not where they can go, inside atmospheres. The craft that fall into this category only freefall if they want to and they represent most all of the ships that you as the player can buy and fly in the game.

Flightgear is an open source project, if their source is well documented (and not a 'black box', yes I get it) then they could be a valuable resources for modeling the basics of atmospheric flight in a satisfyingly real way.
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Re: Planetary Flight: Unit settings

Post by travists »

That would be assuming they don't burn up on reentry. But generally I agree, between the thrust the ships can generate, and repulsor beams ships can fly just fine.
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Re: Planetary Flight: Unit settings

Post by pheonixstorm »

klauss wrote:
pheonixstorm wrote: * Should all units be able to handle atmospheric flight or only a select number?
I think all units should be able to attempt it.
Ok, so this will make gravity, friction, areodynamics, etc more vital overall. Now the question should be, how do we handle craft such as the Ox attempting either planetary landings or using the atmosphere to manuever. I know just to hover would require thrusters on the bottom of the craft (which could also be used for landing) but if it does attempt to land we come across another problem. Exactly how? I would need to view the model again but the ox doesn't exactly look capable of landing on a planet. Should we then model something akin to a space elevator or have all planets require some type of space station to dock at.
pheonixstorm wrote: * Should we set a new field in units.csv? A boolean yes/no?
No, I'd go for air resistance and friction numbers. Atmo-capable ships should be aerodynamic enough that air resistance doesn't build up too fast for shields/armor to cope with it.

Air resistance would be the air resistance coefficient, the ratio of speed vs opposite force.

Friction numbers would be a way to include artificial items like shields into the mix, and would be the ratio of speed vs damage.

Now, aerodynamic ships would receive damage slowly enough that shields would be able to survive landing, while non-aerodynamic ships would simply burn up.

I think one thing you may not be thinking of is that the friction and burn up probably would not be a factor is a powered reentry. Modern space craft afaik do not use any kind of powered reentry and thus have not means of slowing themselves to a point where friction does not become a problem. Yes it would require a lot more fuel to enter an atmosphere and a speed slow enough not to burn up, but even a non aerodynamic ship with heat shielding should be able to skim or enter in the atmosphere without burning up. The overall problem will probably not revolve around entry but the ability to keep a set speed during reentry to allow landing rather than becoming a flying brick (such as the now retired space shuttle).
pheonixstorm wrote: * How do we handle landings? Dock method or manual landings.
I'd go for dock method, but you can place the docking markers on the ground, and make people fly there. You could also place more docking markers, meaning more than one base per planet. Would have to think about this a bit. Maybe as subunits...

An afterthought, would we still allow docking while in orbit? If so, would we have a primary landing zone say the first subunit being the default landing location? This really opes up having smaller corporate spaceports, pirate/smuggler ports, or even just ports on different continents as trade hubs limited only by the artist willing to create such things.
Wheels are not necessary IMO. We can expect repulsor beam-laden landing platforms.
I could only see this being used for local militia inter-system craft if that, maybe only for atmospheric craft only. For landing (even for current craft) I would only look into landing struts or skids. Best example being the landing struts seen in the star wars movies (original trilogy). I don't see wheels as being in use this far into the technological future.

As far as flightgear.. its worth a look but they have a few dependencies that may also have to be looked into depending on how they are built into the code such as open scene graph.
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Re: Planetary Flight: Unit settings

Post by travists »

pheonixstorm wrote: Now the question should be, how do we handle craft such as the Ox attempting either planetary landings or using the atmosphere to manuever. I know just to hover would require thrusters on the bottom of the craft (which could also be used for landing) but if it does attempt to land we come across another problem. Exactly how? I would need to view the model again but the ox doesn't exactly look capable of landing on a planet. Should we then model something akin to a space elevator or have all planets require some type of space station to dock at.
...
An afterthought, would we still allow docking while in orbit? If so, would we have a primary landing zone say the first subunit being the default landing location? This really opes up having smaller corporate spaceports, pirate/smuggler ports, or even just ports on different continents as trade hubs limited only by the artist willing to create such things.
I think this could add some variety to the game. Some major planets have several space elevators to handle transporting goods. Some have multiple spaceports equipped to handle anything that can make planet-fall. Still others have only a small spaceport and large ships will require a shuttle. (That idea has been kicked around for the ox and trading with stations too!)
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Re: Planetary Flight: Unit settings

Post by TBeholder »

pheonixstorm wrote: Ok, so this will make gravity, friction, areodynamics, etc more vital overall. Now the question should be, how do we handle craft such as the Ox attempting either planetary landings or using the atmosphere to manuever. I know just to hover would require thrusters on the bottom of the craft (which could also be used for landing) but if it does attempt to land we come across another problem. Exactly how? I would need to view the model again but the ox doesn't exactly look capable of landing on a planet. Should we then model something akin to a space elevator or have all planets require some type of space station to dock at.
Probably having some sort of undercarriage. Maybe, implemented landing flags, much like tractorability flags? To enable landing, assisted launch systems use (a ship should have some sort of carriage for most catapults), etc.
Of course, anything can be held in a tractor/repulsor cradle and catapulted by repulsor as long as you have one big enough and don't mind its power expenses.
As to bulk transports running transactions with planets, sanity suggests it's a job for shuttles. :) Maybe, for NPC this already can be done, after all they do land properly at docks in the end of escort missions...
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Re: Planetary Flight: Unit settings

Post by Dair »

FG is very readable and organized, well maintained and documented. But it should be noted that it uses many Flight Dynamics Models, and the aircraft creator chooses which one to use, the people who have real good datasets generally use JSBSim which replaced the old LaRCsim system in 2000, if you want to use the geometry as the base, and then "tweak" to find the right feel you will want to use YASim, this is likely the best FDM for your purpose as your dealing with fictional crafts. UIUC is really only of great use if you like the idea of applying Icing effects to wings.

The open scene graph is mostly tied to the scene manage, terrain tiling, and cockpit UI etc. I don't think it will be an issue, but I think mostly you will want to consider whether their multiple FDM approach is of use, I am thinking one FDM will be good for your purposes, but perhaps their system could be useful on how to hook into and use multiple systems as you'll be transitioning from Space into Low-orbital flight.

FG is really quite advanced and has some really interesting and amazing features, I'm not sure how many would be all the interesting, but they do have a weather system, when I was last involved they were able to pull weather data for an area on earth and apply it to flight, and people where working on a new weather system which created proper thermals and effects, but this might be too much for your needs, I'm not even sure if they completed it, there seemed to be discussion as to whether such a thing was needed back then.

One thing of interest might be a shader they developed to create a decent looking City and Forest effect without creating alot of objects, although I still think having static batched objects up very close looks better it did create a very nice effect from several thousand feet up and more of cities and forests down low and might be worth a look. Alot of times thats the biggest hit is trying to draw too many surface objects. They use satellite data to create the terrain though, and tile it, the world terrain is very large, and the tiles are typically uploaded to the player by a server as needed when they are flying around the world. Its a very interesting system but perhaps in many aspects much more detailed then you need, still they have some great AI and traffic control code too, its all well organized so finding your way around should be quite easy.

You'll likely mostly be interested in the FDM directory in the source code.

Just thought I'd give some input as I created some models and worked with and still play sometimes FG so I'm familiar with its inner working to some degree.
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Re: Planetary Flight: Unit settings

Post by pheonixstorm »

Yeah. Cities, landscapes, and other terrain features is another threads worth of discussion though as would be the actual flight dynamics and what we would really want to simulate while inside the atmosphere.
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Re: Planetary Flight: Unit settings

Post by log0 »

FG is really quite advanced and has some really interesting and amazing features, I'm not sure how many would be all the interesting, but they do have a weather system, when I was last involved they were able to pull weather data for an area on earth and apply it to flight, and people where working on a new weather system which created proper thermals and effects, but this might be too much for your needs, I'm not even sure if they completed it, there seemed to be discussion as to whether such a thing was needed back then.
I think it would be much easier to add space flight to FG than the other way around.
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Re: Planetary Flight: Unit settings

Post by Hicks »

https://docs.google.com/spreadsheet/ccc ... 3WGc#gid=0
i added a column to calculate top acceleration from the top thrust listed in the units.csv, there is about 170 varients of ships that have over 1 g top acceleration, so those ships should be able to do planetary landing at their current state. Of course a hold full of heavy dense metal might change a few things. With fligh dynamics it would mean a few more ships could be added to the list and they will be able to carry a bit more weight
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Re: Planetary Flight: Unit settings

Post by ezee »

Hi .

I have coded some plugin for the space simulator Orbiter years ago .
There is a sdk , and atmospheric flight is well decribed and rendered.
It is a hard core simulator , a reference in space sim .
( http://youtu.be/MQBiX8STHUk )

too much for an action game , but a bit of sim is good for simmers !
:wink:

You will find formulas here :
https://bitbucket.org/face/orbiter/src/ ... t=default#

For exemple :
5.1 Contents
Elliptic orbits
The orbit in space
Kepler’s equation
5.2 Elliptic orbits
This page provides a summary of parameters for ideal 2-body orbital elements.
Conic section: The trajectory of an object under the influence of the gravitational field generated by a point
mass follows a conic section. This may be either periodic (closed circular or elliptic orbit) or nonperiodic
(open parabolic or hyperbolic orbit). The equation of a conic section with the focus in the origin is given in polar coordinates byr =p1 + e cos()
with eccentricity e and semi-latus rectum p.
Standard gravitational parameter: In the following, the standard gravitational parameter is defined as
the product of the gravitational constant G and the mass M of the central body at focus F:= GM
or
5.4 The orbit in space
The orientation of the orbital trajectory in space, relative to the reference body, is defined by three parameters
(in addition to the two parameters describing the shape):

The position of the orbiting object along the orbit is defined by an additional parameter, the true longitude.
The orientation of an orbit in space is defined with respect to a frame of reference. For planetary orbits, the
reference is usually given by the plane of the ecliptic and direction of the vernal equinox. For satellites in
Earth orbit, the equatorial plane usually defines the reference plane.
Inclination: The inclination i defines the tilt of the orbital plane against the reference plane. The intersection
of the orbital plane with the reference plane is denoted as the line of nodes.
Ascending and descending node: The line of nodes always passes through the orbit reference body (S).
The nodes N1 and N2 are the points where the orbital trajectory intersects the reference plane.
If the direction of orbit is such that the orbiting body passes the plane of the ecliptic from south to north at N1,then N1 is the ascending node, and N2 is the descending node.
Longitude of ascending node: The angle between the reference direction and node N
of the ascending node ().
Argument of periapsis: The angle between node N1 is the longitude1 and periapsis A is the argument of periapsis (!).
Longitude of periapsis: The sum $ = + ! is called the longitude of periapsis.
True longitude: The sum of longitude of periapsis and true anomaly,
L = $ + = + ! +
is called the true longitude of the orbiting body.
In the sdk :https://bitbucket.org/face/orbiter/src/ ... at=default
/**
* \ingroup structures
* \brief Planetary atmospheric constants structure
*/
typedef struct {
double p0; ///< pressure at mean radius ('sea level') [Pa]
double rho0; ///< density at mean radius
double R; ///< specific gas constant [J/(K kg)]
double gamma; ///< ratio of specific heats, c_p/c_v
double C; ///< exponent for pressure equation (temporary)
double O2pp; ///< partial pressure of oxygen
double altlimit; ///< atmosphere altitude limit [m]
double radlimit; ///< radius limit (altlimit + mean radius)
double horizonalt; ///< horizon rendering altitude
VECTOR3 color0; ///< sky colour at sea level during daytime
} ATMCONST;

/** \brief Atmospheric parameters structure */
typedef struct {
double T; ///< temperature [K]
double p; ///< pressure [Pa]
double rho; ///< density [kg/m^3]
} ATMPARAM;
The source are compiled , but the headers are a good starting point to elude a strategy .
Perhaps :wink:

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            {
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                return ThreatLevel::None;
            }
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TBeholder
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Re: Planetary Flight: Unit settings

Post by TBeholder »

Hicks wrote:i added a column to calculate top acceleration from the top thrust listed in the units.csv, there is about 170 varients of ships that have over 1 g top acceleration,
Basecomputer stats screen does this on the fly. ;)
Hicks wrote: so those ships should be able to do planetary landing at their current state. Of course a hold full of heavy dense metal might change a few things.
Of course they can. And fusion reactors give them excess of power. Also, ships intended for atmospheric landing should be able to get propellant right there and sacrifice exhaust velocity for raw thrust - i.e. they can be expected to have something from Type 1 ("more fuel") afterburner to separate turbofans built in.
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