Update Deepstar development

Axel

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@Izack
With normal RCS of todays nitrogene could gass technology we had to reduce the RCS by factor 1000, but then it would be very challenging/impossible to control that monster, with tools like TransX or IMFD. The problem is the very big mass of the ship.
Yes the RCS is a way to strong for that huge ship, if we would use todays normal nitrogene RCS thrusters, but we don't use it! We use instead big turbo rotating wheels for the main job of that (for rotate). For translate we use a bigger version of the shuttle OMS (orbiter manover system), which is a hot chemical engine. The fact that the rotate-system has no fuel consumption and the translate-mode has hypotetical Isp of 3800ms, its ok to use the Isp of the main engine of the ship. Ofcourse it would be more real to split these systems with own Isp's and tanks, but this would need a more complex DLL for the addon. Maybe somebody can do this?

I'm also trying my hand at custom exhaust textures, both for the primary fusion beams and the MHD thrusters...and failing utterly. Perhaps 80mileshigh or someone else would like to contribute?

I have the solution! I give you the permission to use my exhaust-texture from my Perseus MKII-update, but we have to ask Perseus, the original autor although. The texture is "textures\Perseus_IEx.dds". Its from the Ion engine of perseus-ship, but this gives a nice plasma beam exhaust, very similar to fusion plasma, look right down at the addons picture at orbit hangar!

[ame="http://www.orbithangar.com/searchid.php?ID=4908"]Perseus Launcher & Perseus MkII 1.3[/ame]
 
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Izack

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@Izack
With normal RCS of todays nitrogene could gass technology we had to reduce the RCS by factor 1000, but then it would be very challenging/impossible to control that monster, with tools like TransX or IMFD. The problem is the very big mass of the ship.
Yes the RCS is a way to strong for that huge ship, if we would use todays normal nitrogene RCS thrusters, but we don't use it! We use instead big turbo rotating wheels for the main job of that (for rotate). For translate we use a bigger version of the shuttle OMS (orbiter manover system), which is a hot chemical engine.
Ah, I wouldn't have guessed there were gyroscopes; the mesh has no indicator of them near the centre of mass. From what I can tell, though, even enormous gyroscopes would be fairly weak, unless they were a significant part of the vessel's structure. As it is, though, with the MHD thruster clusters, the torque is 12 million Nm - not negligible, even for such a massive vessel. I don't know about TransX, but IMFD is capable of handling that at 10x time, if the user orients the spacecraft in roughly the right direction before the burn. I see your point about ease of use, though. I'll have to put attitude thrust in a config file, with some options for the user (turbo-gyroscopes, nitrogen thrusters, MHD thrusters, hot-fire chemical thrusters.)
The fact that the rotate-system has no fuel consumption and the translate-mode has hypotetical Isp of 3800ms, its ok to use the Isp of the main engine of the ship. Ofcourse it would be more real to split these systems with own Isp's and tanks, but this would need a more complex DLL for the addon. Maybe somebody can do this?
I already have the attitude thrusters feeding off a 6-tonne helium reserve. ;)
I have the solution! I give you the permission to use my exhaust-texture from my Perseus MKII-update, but we have to ask Perseus, the original autor although. The texture is "textures\Perseus_IEx.dds". Its from the Ion engine of perseus-ship, but this gives a nice plasma beam exhaust, very similar to fusion plasma, look right down at the addons picture at orbit hangar!

Perseus Launcher & Perseus MkII 1.3
:thankyou: This is very helpful!

---------- Post added at 10:15 AM ---------- Previous post was at 08:12 AM ----------

Monopropellant thrusters are now pushing Deepstar forward and backward, feeding off yet another small propellant reserve (UDMH). I don't have them defined very accurately, though - what model of thruster do you want to use?
 

Urwumpe

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Monopropellant thrusters are now pushing Deepstar forward and backward, feeding off yet another small propellant reserve (UDMH). I don't have them defined very accurately, though - what model of thruster do you want to use?

UMDH requires an oxygen source for combustion. Maybe you mean Hydrazine.

Why don't you use an electrostatic or electromagnetic propulsion system for the RCS? The electrical power should be available on the Deepstar. A MPDT could be a choice there (up to 200 N thrust possible per thruster and a prototype was already flown in space) , the less sophisticated versions could be Resistojets (simply boiling a propellant by heating a wire coil).
 

Izack

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UMDH requires an oxygen source for combustion. Maybe you mean Hydrazine.
My mistake - yes, I did mean Hydrazine.
Why don't you use an electrostatic or electromagnetic propulsion system for the RCS? The electrical power should be available on the Deepstar. A MPDT could be a choice there (up to 200 N thrust possible per thruster and a prototype was already flown in space) , the less sophisticated versions could be Resistojets (simply boiling a propellant by heating a wire coil).
The Deepstar I'm working on is currently using 20kN MPDTs in clusters of four.
 

Urwumpe

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My mistake - yes, I did mean Hydrazine.

The Deepstar I'm working on is currently using 20kN MPDTs in clusters of four.

20 kN ? Oh my.... :hailprobe: ... I don't want to see your electricity bill.

And no CMGs?
 

Izack

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20 kN ? Oh my.... :hailprobe: ... I don't want to see your electricity bill.

And no CMGs?

:lol: Now that you mention it, that should be about 192 GW if all thrusters fired simultaneously, or at least 32GW to fire two clusters used in rotation. Perhaps a redesign is in order.

As for CMGs, I don't really know enough about how they work at the moment to begin implementing them...

What kind of angular acceleration could a CMG system impart on Deepstar? What kind of power and space requirements would that have?
 
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Urwumpe

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As for CMGs, I don't really know enough about how they work at the moment to begin implementing them...

What kind of angular acceleration could a CMG system impart on Deepstar? What kind of power and space requirements would that have?

Really low acceleration and really slow rotation speeds. but what can keep the ISS oriented in space might not be wrong for for the Deepstar.

A CMG of about 100 kg mass and a few 100 Watts of power consumption provides torques in the kilonewtonmeter range.

Essentially it works by having four massive gyroscopes spinning at high constant speed. For rotating the vessel, you change the rotation axis of the each gyroskope, so the total change in rotation impulse on your vessel is generated by the sum of all small rotation impulse changes for the CMGs.

Since the Deepstar will also have strong gravity gradient torques close to a planet, it might even be possible to desaturate the CMGs without use of fuel.
 

Izack

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Alright, having a look at Poscik's CMG code. First thing I notice is quaternion class. Hello, Math. It's been a while.

---------- Post added at 02:56 PM ---------- Previous post was at 12:26 PM ----------

Does anyone have a suggestion for an effective attitude-control thruster in the kN range? The Space Shuttle R-40A is inadequate: clusters of of four only give 2.3MNm torque, which is inadequate. (Aside from reaction wheels, which I'd like to use for maintaining attitude in interplanetary flight, not manoeuvring.)
 

MaverickSawyer

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Gimme a little time to look around. I'll try to find something.

EDIT: Nope, those appear to be the largest RCS thrusters out there. You'll have to make something yourself. :p
 
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Izack

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Gimme a little time to look around. I'll try to find something.

EDIT: Nope, those appear to be the largest RCS thrusters out there. You'll have to make something yourself. :p

Yep, had my own look around as well, and decided to simply go with a fictional 20kN, 3km/s exhaust velocity chemical thruster, clustered in groups of four as before. Power requirement has, of course, dropped by about 99%. :lol:
 
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Axel

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@80mileshigh
Your new thrusters are looking beautifull!

@Izack
Alright, having a look at Poscik's CMG code. First thing I notice is quaternion class. Hello, Math. It's been a while.
I find the handling of the addon is not easy, harder to control than a complet spaceship :lol:! Try to set the fuel consumption for rotate just to ZERO or ISP to a veeeeeeeryyyyyy high value thats all and we have a working gyroscope.


Yep, had my own look around as well, and decided to simply go with a fictional 20kN, 3km/s exhaust velocity chemical thruster, clustered in groups of four as before. Power requirement has, of course, dropped by about 99%.

Thats a very wisely decision, MHD thrusters for attitude control are cool, but unrealistic because the main engine needs the 99% power :thumbup:
And im imagine about the bigness/diameter of cables for 32GW power, which are going to all sides of the ship.
And chemical thrsuters can use allthough the same fuel like the main engine, when we use hydrogene. At the attitude control thrusters we give an oxidator to it. The nozzles itself are made from ceramic and not metal, so they are reusable allthough for a long time.
But it would be very nice if you could split the rotate and translate mode in relation of fuel consumption? Is that possible in DLLs ?
Else i have to dock "Poscik's CMG" to one of deepstar's docking ports and have to learn its handling at a 2 year-study :lol:.
To use propellants for rotate modes is for small vessels a simply, powerfull and good idea, but not for long time vessels like ISS and deepstar, because the most command is here "Killrot", we not often need translate. And the deepstar itself would not have to dock itself, more realistic is that small shuttles will support the ship, when it is waiting in parking orbit or in a position near a station.
 
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Izack

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Thats a very wisely decision, MHD thrusters for attitude control are cool, but unrealistic because the main engine needs the 99% power :thumbup:
And im imagine about the bigness/diameter of cables for 32GW power, which are going to all sides of the ship.
And chemical thrsuters can use allthough the same fuel like the main engine, when we use hydrogene. At the attitude control thrusters we give an oxidator to it. The nozzles itself are made from ceramic and not metal, so they are reusable allthough for a long time.
But it would be very nice if you could split the rotate and translate mode in relation of fuel consumption? Is that possible in DLLs ?
Else i have to dock "Poscik's CMG" to one of deepstar's docking ports and have to learn its handling at a 2 year-study :lol:.
To use propellants for rotate modes is for small vessels a simply, powerfull and good idea, but not for long time vessels like ISS and deepstar, because the most command is here "Killrot", we not often need translate. And the deepstar itself would not have to dock itself, more realistic is that small shuttles will support the ship, when it is waiting in parking orbit or in a position near a station.

The thing with CMGs is that, to be easily useable in a Deepstar-sized vessel, they would need to be absolutely enormous, and rotation would be many times more sluggish than even the current system.

I couldn't in good conscience code thrusters with faster-than-light exhaust velocity - CMGs require detorquing, either by gravity gradient torque or through an attitude system. I was going to model this, but to be honest, the gains would be so disproportionately low compared to the effort, it's not really worth it: the attitude control would be practically useless to the average user, especially when needing quick ACS response while orbiting close to a planetary body, where your burn vector will rapidly elude you as you try to combat both the changing velocity vector and the gravity gradient. Because of this, I think the chemical rockets are the best solution: they would be required for detorquing a CMG anyway, and afford the Deepstar a certain grace as it slowly (but not too slowly) turns to face its burn vector, or reposition the radiators wrt Sol, or shield the crew from solar storms, or just get a better view from the command deck window. :2cents:

If fear of fuel waste is a problem, I'd recommend the Absolute Killrot plugin. Actually, I could easily include that code in Deepstar to prevent dependancies.
 

80mileshigh

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I've nearly finished updating the model with fusion drive and RCS. I'm not sure if the RCS looks quite right on the ship. Just from an aesthetic point of view, it might spoil the lines of the ship a bit.

I'll post some preview shots soon, see what you all think, and then send the model through to Izack and Axel. This might take another week or so. I've got a few things competing for my attention at the moment. :)
 

Axel

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@Izack
CMGs require detorquing, either by gravity gradient torque or through an attitude system.

Oh damn, i didn't register it right, thats ofcourse a big problem, Deepstar is a interplanetary vessel and not a space station, its most time not near a planet for detorquing. The mass of the big wheels we can use better for extra RCS fuel. ISS uses 4 CMG's, every weights 100 kg and is about 1,5 m in diameter and 0,50 m high. For deepstar, when we use although 4 wheels for same , every would weight 3300kg and would be 6 m diameter at 1 m hight. Thats not to big, but useless beause the needing for detorquing and to slow.
But a single CMG would be well only for "Killrot" for avoiding a wild spinning of the ship in all directions at 100000x time step. That would save alot fuel. But we have allready a big CMG - its the big rotation area of the ship with the 2 living modules at the end for artificial gravity! My question, is it possible to simulate a permanent Killrot-command, if the rotaing section is active, without the needing of the pilot to do that permanently? It works fine with every single vessel, when we give it a spin (its a feature of orbiters physic engine itself). Or alternativly you let the ship execute the command Killrot after 1 hour automaticly permanently, if no keyboard action of the pilot has been registered and the hab module roatation is "On".

How big is the thrust of your complet RCS now? 20kN thrust for a action? And how big is the tank volume, 6 mT helium seems to be to less, helium is only a propellant for a RCS fuel, like hydrogene AND an oxidizer when we not using turbo pumps.
MY old plan was to use although the big main engine for RCS, thats the reason because the big thrust of 10 MN - per thrust vector control like space shuttle' main engine at start to LEO. But its technically to difficult for a fusion drive and we get only a few degress of nozzle moving, but it would be possible to steer the complet ship with it, rotate it to all vectors. But with every rotate-command we would get a extra translate drifting, that to simulate in a DLL is a way to complicate i guess? And we would need a animation of nozzle moving.

@80mileshigh
I registered a high spin of the ship, hab-anim on or off, automaticly after short time, faster and faster. Thats a bug i guess!
 
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80mileshigh

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@80mileshigh
I registered a high spin of the ship, hab-anim on or off, automaticly after short time, faster and faster. Thats a bug i guess!

Thanks for spotting this.

I can reproduce this behaviour if I start in one of the scenarios in the range 2.0 - 3.2 inclusively (Jovian and Saturnian systems).

If I start from scenarios 1.0,1.1 or 4.0-5.3 the ship seems stable.

Can you check if this is the same on your end?

It may be a problem with orbital elements or scenario states being copied across from Orbiter 2006? If so I'll just create new scenarios and upload an update.
 

Urwumpe

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I wouldn't call the CMGs "useless" - for claiming that, there would have to be something better. Magic electrical thrusters with infinite ISP and kN thrust? would not happen too soon and be not really realistic. The early plans for using MHD thrusters, which had been realistic by their properties and probable by the thrust level, had a power consumption in the GW range : Much more than a huge stationary nuclear power station produces.

Also you can't put infinite torques on a spacecraft - it would need to become much more heavy and robust then, lowering the performance of it.
 

Izack

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@Axel

Using the habitated centrifuge in attitude control won't work, for two reasons: it is fixed to the ship, and thus its rotational axis cannot be rotated mechanically relative to the rest of the vehicle, making it useless as a CMG, and it must rotate at constant speed for crew comfort, making it useless as a reaction wheel. It will however introduce complications when attempting to rotate normally with thrusters, because of its rotation. :shrug:

A permanent killrot isn't difficult. Essentially, "if angular velocity is near zero, set angular velocity to zero."

The current RCS propellant tank mass is a placeholder at present - it could be modified to whatever you believe is reasonable.

@80mileshigh That's good to hear! No rush. :)

Have the meshgroups changed order since the 2.0 release? I can't seem to make the 2.1 mesh's animations work properly, because of problems with the mesh groups.
 

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Have the meshgroups changed order since the 2.0 release? I can't seem to make the 2.1 mesh's animations work properly, because of problems with the mesh groups.

Yes, there are fewer mesh groups now, I was able to join some of them (mesh optimisation).

Try this:
Code:
;-----------------Hab Rotation
;Radius=68 meters
;Angular Velocity=2 rotations/minute
;Tangential Velocity=14.242 meters/second
;Centripetal Acceleration=0.304 g

[ANIM_SEQ_0]
KEY=G
DURATION=30.211
REPEAT=1

[ANIM_COMP_0]
SEQ=0
GROUPS=2,3,4,5,38,39,61
RANGE=(0.0,1.0)
TYPE=ROTATE
ROT_PNT=(0,0,0)
ROT_AXIS=(0,0,1)
ANGLE=360


;-----------------Port Dish

[ANIM_SEQ_1]
KEY=1
DURATION=20
REPEAT=1

[ANIM_COMP_1]
SEQ=1
GROUPS=21,22,23,24
RANGE=(0.0,1.0)
TYPE=ROTATE
ROT_PNT=(-70.541,4.943,-28.524)
ROT_AXIS=(0,1,0)
ANGLE=360

[ANIM_SEQ_2]
KEY=2
DURATION=20
REPEAT=1

[ANIM_COMP_2]
SEQ=2
GROUPS=21,22,23,24
RANGE=(0.0,1.0)
TYPE=ROTATE
ROT_PNT=(-70.541,4.943,-28.524)
ROT_AXIS=(0,1,0)
ANGLE=-360

;-----------------Starboard Dish

[ANIM_SEQ_3]
KEY=3
DURATION=20
REPEAT=1

[ANIM_COMP_3]
SEQ=3
GROUPS=33,34,35,36
RANGE=(0.0,1.0)
TYPE=ROTATE
ROT_PNT=(70.541,4.943,-28.524)
ROT_AXIS=(0,1,0)
ANGLE=360

[ANIM_SEQ_4]
KEY=4
DURATION=20
REPEAT=1

[ANIM_COMP_4]
SEQ=4
GROUPS=33,34,35,36
RANGE=(0.0,1.0)
TYPE=ROTATE
ROT_PNT=(70.541,4.943,-28.524)
ROT_AXIS=(0,1,0)
ANGLE=-360

;-----------------Nose dock

[ANIM_SEQ_5]
KEY=K
DURATION=15
REPEAT=0

[ANIM_COMP_5]
SEQ=5
GROUPS=50,55
RANGE=(0.0,0.3)
TYPE=ROTATE
ROT_PNT=(0.994,0,138.077)
ROT_AXIS=(0,1,0)
ANGLE=160

[ANIM_COMP_6]
SEQ=5
GROUPS=51,56
RANGE=(0.0,0.3)
TYPE=ROTATE
ROT_PNT=(-0.994,0,138.077)
ROT_AXIS=(0,1,0)
ANGLE=-160

[ANIM_COMP_7]
SEQ=5
GROUPS=53,54,52
RANGE=(0.3,1.0)
TYPE=TRANSLATE
SHIFT=(0,0,1)
And for the landers:
Code:
[ANIM_SEQ_0]
KEY=K
DURATION=6
REPEAT=0

[ANIM_COMP_0]
SEQ=0
GROUPS=9
RANGE=(0.0,1.0)
TYPE=ROTATION
ROT_PNT=(0.559,0,-4.754)
ROT_AXIS=(0,1,0)
ANGLE=-90
The new mesh groups on Deepstar will probably mess this up, but this should work for now.

Thanks! :cheers:
 

Izack

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I wouldn't call the CMGs "useless" - for claiming that, there would have to be something better. Magic electrical thrusters with infinite ISP and kN thrust? would not happen too soon and be not really realistic. The early plans for using MHD thrusters, which had been realistic by their properties and probable by the thrust level, had a power consumption in the GW range : Much more than a huge stationary nuclear power station produces.

Also you can't put infinite torques on a spacecraft - it would need to become much more heavy and robust then, lowering the performance of it.
In a real-world scenario, where any incredibly expensive mission would be carefully and meticulously planned out, a CMG array would be a completely feasible solution - but Orbiter gameplay is another story, IMO. In the Orbiterworld, realism is more of a design aesthetic and philosophy than an actual limitation. Developers strive for realistic constraints rather than attempt to break them. Some projects (such as the SSU project you are involved in) push further towards realism than others, either because they want to shorten the development cycle for themselves, or because they aim for greater accessibility. In this case, both play a role. I want my contribution to the Deepstar project to make it immersive and interesting to users while maintaining reasonable ease of use, within the realistic aesthetic. The Deepstar is referred to as a general-purpose DSV, and so it must be designed for whatever unknown missions the players will use it for, whether it's an imitation of such a meticulously planned mission, or spawning a vessel, letting loose and hailing Probe. For this, I think it basically needs to be able to turn 180° in less than an hour, just in case, but while maintaining the sense of the sluggishness of a large moving structure and without straying too far from the plausible.

TL;DR: True, but no thanks. :p

Yes, there are fewer mesh groups now, I was able to join some of them (mesh optimisation).

Thanks much! Barring geometry changes, mesh updates shouldn't hinder the development on this end at all. :)
 
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