Ship Design Philosophy

Discuss the Traveller RPG and its many settings
Condottiere
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Re: Ship Design Philosophy

Postby Condottiere » Fri Jan 11, 2019 11:49 pm

Speaking of Harrington, as I recall, you can see death coming if the other side launches enough missiles.
Condottiere
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Re: Ship Design Philosophy

Postby Condottiere » Sun Jan 13, 2019 12:07 pm

Inspiration: Astartes (Warhammer Forty Kay Fan Film)

https://www.youtube.com/watch?v=g-MteECxZUY
https://www.youtube.com/watch?v=mfGPMJ8A0QY
https://www.youtube.com/watch?v=CMGRa4_UjE4

Boarding action; plausible, if you can blast a hole through armour plating.
phavoc
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Re: Ship Design Philosophy

Postby phavoc » Sun Jan 13, 2019 2:57 pm

Condottiere wrote:
Wed Jan 02, 2019 6:12 pm
Spaceships: Hulls and Heat Shields

There are four critical parameters considered when designing a vehicle for atmospheric entry:
Peak heat flux
Heat load
Peak deceleration
Peak dynamic pressure
Peak heat flux and dynamic pressure selects the TPS material. Heat load selects the thickness of the TPS material stack. Peak deceleration is of major importance for manned missions. The upper limit for manned return to Earth from low Earth orbit (LEO) or lunar return is 10g.[52] For Martian atmospheric entry after long exposure to zero gravity, the upper limit is 4g.[52] Peak dynamic pressure can also influence the selection of the outermost TPS material if spallation is an issue.
Starting from the principle of conservative design, the engineer typically considers two worst case trajectories, the undershoot and overshoot trajectories. The overshoot trajectory is typically defined as the shallowest allowable entry velocity angle prior to atmospheric skip-off. The overshoot trajectory has the highest heat load and sets the TPS thickness. The undershoot trajectory is defined by the steepest allowable trajectory. For manned missions the steepest entry angle is limited by the peak deceleration. The undershoot trajectory also has the highest peak heat flux and dynamic pressure. Consequently, the undershoot trajectory is the basis for selecting the TPS material. There is no "one size fits all" TPS material. A TPS material that is ideal for high heat flux may be too conductive (too dense) for a long duration heat load. A low density TPS material might lack the tensile strength to resist spallation if the dynamic pressure is too high. A TPS material can perform well for a specific peak heat flux, but fail catastrophically for the same peak heat flux if the wall pressure is significantly increased (this happened with NASA's R-4 test spacecraft).[52] Older TPS materials tend to be more labor-intensive and expensive to manufacture compared to modern materials. However, modern TPS materials often lack the flight history of the older materials (an important consideration for a risk-averse designer).
Based upon Allen and Eggers discovery, maximum aeroshell bluntness (maximum drag) yields minimum TPS mass. Maximum bluntness (minimum ballistic coefficient) also yields a minimal terminal velocity at maximum altitude (very important for Mars EDL, but detrimental for military RVs). However, there is an upper limit to bluntness imposed by aerodynamic stability considerations based upon shock wave detachment. A shock wave will remain attached to the tip of a sharp cone if the cone's half-angle is below a critical value. This critical half-angle can be estimated using perfect gas theory (this specific aerodynamic instability occurs below hypersonic speeds). For a nitrogen atmosphere (Earth or Titan), the maximum allowed half-angle is approximately 60°. For a carbon dioxide atmosphere (Mars or Venus), the maximum allowed half-angle is approximately 70°. After shock wave detachment, an entry vehicle must carry significantly more shocklayer gas around the leading edge stagnation point (the subsonic cap). Consequently, the aerodynamic center moves upstream thus causing aerodynamic instability. It is incorrect to reapply an aeroshell design intended for Titan entry (Huygens probe in a nitrogen atmosphere) for Mars entry (Beagle-2 in a carbon dioxide atmosphere).[citation needed][original research?] Prior to being abandoned, the Soviet Mars lander program achieved one successful landing (Mars 3), on the second of three entry attempts (the others were Mars 2 and Mars 6). The Soviet Mars landers were based upon a 60° half-angle aeroshell design.
A 45° half-angle sphere-cone is typically used for atmospheric probes (surface landing not intended) even though TPS mass is not minimized. The rationale for a 45° half-angle is to have either aerodynamic stability from entry-to-impact (the heat shield is not jettisoned) or a short-and-sharp heat pulse followed by prompt heat shield jettison. A 45° sphere-cone design was used with the DS/2 Mars impactor and Pioneer Venus Probes.

Image
This is not an issue in the Traveller universe, or any other, so long as they have control over gravity. Assuming they are trying to make an entry into the atmosphere without their contragravity system working, then it would remain applicable, though materials would alter the calculations. All they would need to do is match the orbital rotation velocity and simply sink into the atmosphere. We cannot do that today, so you never see any calculations or discussions on it.
Condottiere
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Re: Ship Design Philosophy

Postby Condottiere » Sun Jan 13, 2019 3:45 pm

It was more relevant in the last edition, when rockets were smaller and cheaper, and I had a clear idea how high burn thrusters functioned.

I'm also slowly moving to more or less to one shot assault shuttles and/or drop pods.
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Re: Ship Design Philosophy

Postby Condottiere » Sun Jan 13, 2019 11:27 pm

Spaceships: Life Support and Carbon dioxide scrubber

Lithium hydroxide[edit]
Other strong bases such as soda lime, sodium hydroxide, potassium hydroxide, and lithium hydroxide are able to remove carbon dioxide by chemically reacting with it. In particular, lithium hydroxide was used aboard spacecraft, such as in the Apollo program, to remove carbon dioxide from the atmosphere. It reacts with carbon dioxide to form lithium carbonate.[10] Recently lithium hydroxide absorbent technology has been adapted for use in anesthesia machines. Anesthesia machines which provide life support and inhaled agents during surgery typically employ a closed circuit necessitating the removal of carbon dioxide exhaled by the patient. Lithium hydroxide may offer some safety and convenience benefits over the older calcium based products.
2 LiOH(s) + 2 H2O(g) → 2 LiOH·H2O(s)
2 LiOH·H2O(s) + CO2(g) → Li2CO3(s) + 3 H2O(g)
The net reaction being:
2LiOH(s) + CO2(g) → Li2CO3(s) + H2O(g)
Lithium peroxide can also be used as it absorbs more CO2 per unit weight with the added advantage of releasing oxygen.[11]
Regenerative carbon dioxide removal system[edit]
The regenerative carbon dioxide removal system (RCRS) on the space shuttle orbiter used a two-bed system that provided continuous removal of carbon dioxide without expendable products. Regenerable systems allowed a shuttle mission a longer stay in space without having to replenish its sorbent canisters. Older lithium hydroxide (LiOH)-based systems, which are non-regenerable, were replaced by regenerable metal-oxide-based systems. A system based on metal oxide primarily consisted of a metal oxide sorbent canister and a regenerator assembly. It worked by removing carbon dioxide using a sorbent material and then regenerating the sorbent material. The metal-oxide sorbent canister was regenerated by pumping air at approximately 400 °F (204 °C) through it at a standard flow rate of 7.5 cu ft/min (0.0035 m3/s) for 10 hours.[12]
Activated carbon[edit]
Activated carbon can be used as a carbon dioxide scrubber. Air with high carbon dioxide content, such as air from fruit storage locations, can be blown through beds of activated carbon and the carbon dioxide will adsorb onto the activated carbon. Once the bed is saturated it must then be "regenerated" by blowing low carbon dioxide air, such as ambient air, through the bed. This will release the carbon dioxide from the bed, and it can then be used to scrub again, leaving the net amount of carbon dioxide in the air the same as when the process was started.
Metal-organic frameworks (MOFs)[edit]
Metal-organic frameworks are one of the most promising new technologies for carbon dioxide capture and sequestration via adsorption. Although no large-scale commercial technology exists nowadays, several research studies have indicated the great potential that MOFs have as a CO2 adsorbent. Its characteristics, such as pore structure and surface functions can be easily tuned to improve CO2 selectivity over other gases.[13]
A MOF could be specifically designed to act like a CO2 removal agent in post-combustion power plants. In this scenario, the flue gas would pass through a bed packed with a MOF material, where CO2 would be stripped. After saturation is reached, CO2 could be desorbed by doing a pressure or temperature swing. Carbon dioxide could then be compressed to supercritical conditions in order to be stored underground or utilized in enhanced oil recovery processes. However, this is not possible in large scale yet due to several difficulties, one of those being the production of MOFs in great quantities.[14]
Another problem is the availability of metals necessary to synthesize MOFs. In a hypothetical scenario where these materials are used to capture all CO2 needed to avoid global warming issues, such as maintaining a global temperature rise less than 2oC above the pre-industrial average temperature, we would need more metals than are available on Earth. For example, to synthesize all MOFs that utilize vanadium, we would need 1620% of 2010 global reserves. Even if using magnesium-based MOFs, which have demonstrated a great capacity to adsorb CO2, we would need 14% of 2010 global reserves, which is a considerable amount. Also, extensive mining would be necessary, leading to more potential environmental problems.[14]
In a project sponsored by the DOE and operated by UOP LLC in collaboration with faculty from four different universities, MOFs were tested as possible carbon dioxide removal agents in post-combustion flue gas. They were able to separate 90% of the CO2 from the flue gas stream using a vacuum pressure swing process. Through extensive investigation, researchers found out that the best MOF to be used was Mg/DOBDC, which has a 21.7 wt% CO2 loading capacity. Estimations showed that, if a similar system were to be applied to a large scale power plant, the cost of energy would increase by 65%, while a NETL baseline amine based system would cause an increase of 81% (the DOE goal is 35%). Also, each ton of CO2 avoided would cost $57, while for the amine system this cost is estimated to be $72. The project ended in 2010,estimating that the total capital required to implement such a project in a 580 MW power plant was 354 million dollars.[15]


Carbon dioxide scrubbing[edit]
Further information: carbon dioxide scrubber
Lithium hydroxide is used in breathing gas purification systems for spacecraft, submarines, and rebreathers to remove carbon dioxide from exhaled gas by producing lithium carbonate and water:[7]
2 LiOH•H2O + CO2 → Li2CO3 + 3 H2O
or
2 LiOH + CO2 → Li2CO3 + H2O
The latter, anhydrous hydroxide, is preferred for its lower mass and lesser water production for respirator systems in spacecraft. One gram of anhydrous lithium hydroxide can remove 450 cm3 of carbon dioxide gas. The monohydrate loses its water at 100–110 °C.
...
In 2012, the price of lithium hydroxide was about $5,000 to $6,000 per tonne.[8]
Condottiere
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Re: Ship Design Philosophy

Postby Condottiere » Thu Jan 17, 2019 10:51 am

Starships: Hulls and Space/balls

Image

One nifty thing about perfect spheres is that while deckplans tend to expand and contract, you know exactly how much space you're dealing with.

Sphere Shape

Sphere Diagram with r = radius and c - circumference


Image

r = radius
V = volume
A = surface area
C = circumference
π = pi = 3.14159
√ = square root

As an example, a ten tonne polished planetoid:

total space:
r = 3.22117 m
V = 140 m3
A = 130.388 m2
C = 20.2392 m

usable space:
r = 2.99027 m
V = 112 m3
A = 112.365 m2
C = 18.7884 m

hull plus armour factor two = 0.2309 m width
dragoner
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Re: Ship Design Philosophy

Postby dragoner » Thu Jan 17, 2019 4:02 pm

Spheres are good for internal pressurization, as a square will bulge in the center.
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Re: Ship Design Philosophy

Postby Condottiere » Thu Jan 17, 2019 4:51 pm

Probably more of an issue for commercial and unarmoured hulls.

However, that does bring forth a thought.

How deep can this little diving bell submerge, either in our oceans or the swirling maelstrom of a gas giant?
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Re: Ship Design Philosophy

Postby dragoner » Thu Jan 17, 2019 4:55 pm

Physics plays across the board, it doesn't stop per uses, even military. Nevertheless, the military would like spheres for their external structural stability, compare kicking a ball to a box.
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Re: Ship Design Philosophy

Postby Condottiere » Thu Jan 17, 2019 6:42 pm

Starships: Hulls and Space/balls

Image

Seven eighths of an inch steel.

Building The Ultimate Submarine | Building the Ultimate |Spark

People have dreamed of building a submarine for hundreds of years, but only in recent history have we had the technology to do so. Explore to incredible design and engineering feats that were accomplished in creating The Ultimate Submarine.

https://www.youtube.com/watch?v=jfQSJ_8OnLI


Sixteen millimetres of high grade steel, plus MacRibs; three hundred metres.
Condottiere
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Re: Ship Design Philosophy

Postby Condottiere » Fri Jan 18, 2019 12:57 am

Starships: Hulls and Space/balls

1. I could be wrong, but my estimate of iron nickel alloy is that it's about two thirds the strength of Krupp armour plating, so twenty three centimetres would be about six inches, and constant atmospheric braking should make the surface case hardened.

2. Dents probably just have the same alloy poured in and sanded down, probably with a laser.

3. You're going to need a cockpit, though two issues arise, whether it's covered by a canopy and/or if a windscreen gets embedded.

4. Telescoping tripod landing gear seems most appropriate, though I doubt you need much ground clearance.

5. In theory you could have two decks with about three metres clearance, or three decks with about two metres clearance, or a two and a half metre central deck with everything else squeezed in the attic or the cellar.

6. At default, you have an external hatch, but no airlock, which would require a separate two tonne appropriation.

7. Artificial gravity is inherent; it's possible that it would be embedded in the walls, but you could have the field realigned along the equator, rather than follow the curve of the wall, giving a definite up and down.

8. There's a choice between two tonnes of batteries, or a tonne each of a power generator and a fuel tank.

9. A fixed point is a freebie, a turret at default will require a tonne, a power point and cost double.

10. At technological level nine, you have a self sealing hull, and levitation.

11. You could lighten the hull, which makes it twenty five percent cheaper.

12. Then armour plate it, anywhere between five to twelve factors.
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Re: Ship Design Philosophy

Postby Sigtrygg » Fri Jan 18, 2019 5:32 pm

Why are there no portholes in military submarines (the warships not the exploratory and salvage jobbies)...

one of the silliest tropes is a great big window on the bridge of a starship (Star Trek nerds have been arguing this one for decades) - one laser and your entire bridge crew is blinded, fried or just evaporated.

The CIC should be buried away in the deepest most protected part of the ship - see the Expanse rather than Star Wars...
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Re: Ship Design Philosophy

Postby dragoner » Fri Jan 18, 2019 7:17 pm

Condottiere wrote:
Fri Jan 18, 2019 12:57 am
Starships: Hulls and Space/balls

1. I could be wrong, but my estimate of iron nickel alloy is that it's about two thirds the strength of Krupp armour plating, so twenty three centimetres would be about six inches, and constant atmospheric braking should make the surface case hardened.
Very Dieselpunk making spaceships out of steel.

Image
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Re: Ship Design Philosophy

Postby Condottiere » Fri Jan 18, 2019 7:29 pm

I refer to the chemical power plant as a diesel motor.

Image
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Re: Ship Design Philosophy

Postby Condottiere » Fri Jan 18, 2019 7:58 pm

Starships: Hulls and Space/balls

13. Usable space is eight tonnes; three decks with the attic and the cellar each having one and a half tonnes, the central deck would have five tonnes at two and a half metre ceiling, and as per tradition, the sloping sides could be the fuel tanks.

14. Since a sphere has by definition curved walls, any hit not head on would be subject to sloping armour recalculation.

15. Two and a half metres may be too much height, you could reduce it to two and a quarter metres.

16. Basically, you have a cockpit, a computer, one tonne fuel tank, and a one tonne power plant; so that leave four and a half tonnes for either cargo or features and options.

17. One of which could be solar panelling, at a minimum of half a tonne, but promising unlimited usage at basic power plus factor one manoeuvre drive, with or without propulsion, or seventy five percent power efficiency.
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Re: Ship Design Philosophy

Postby Condottiere » Sat Jan 19, 2019 4:03 pm

Starships: Scouts and Scouting

I get the impressions that scoutships are considered as part of the milieu. But how do they fit in exactly?

In military operations, reconnaissance or scouting is the exploration outside an area occupied by friendly forces to gain information about natural features and other activities in the area.

Examples of reconnaissance include patrolling by troops (skirmishers, Long Range Reconnaissance Patrol, U.S. Army Rangers, cavalry scouts, or military intelligence specialists), ships or submarines, manned/unmanned reconnaissance aircraft, satellites, or by setting up covert observation posts. Espionage normally is not reconnaissance, because reconnaissance is a military's special forces operating ahead of its main forces; spies are non-combatants operating behind enemy lines.

Traditionally, reconnaissance was a role that was adopted by the cavalry. Speed was key in these maneuvers, thus infantry was ill-suited to the task. From horses to vehicles, for warriors throughout history, commanders procured their ability to have speed and mobility, to mount and dismount, during maneuver warfare. Military commanders favored specialized small units for speed and mobility, to gain valuable information about the terrain and enemy before sending the main (or majority) troops into the area, screening, covering force, pursuit and exploitation roles. Skirmishing is a traditional skill of reconnaissance, as well as harassment of the enemy.

Types of reconnaissance:
. Terrain-oriented reconnaissance is a survey of the terrain (its features, weather, and other natural observations).
. Force-oriented reconnaissance focuses on the enemy forces (number, equipment, activities, disposition etc.) and may include target acquisition.
. Civil-oriented reconnaissance focuses on the civil dimension of the battlespace (areas, structures, capabilities, organizations, people and events abbreviated ASCOPE).
The techniques and objectives are not mutually exclusive; it is up to the commander whether they are carried out separately or by the same unit.


Scout - tactical
Reconnaissance - operational
Spying - strategic

Pathfinding - scouting in realtime
Surveillance - constant observation
Intelligence - collected data
Probe - poking the bear

When referring to reconnaissance, a commander's full intention is to have a vivid picture of his battlespace. The commander organizes the reconnaissance platoon based on:
. mission,
. enemy,
. terrain,
. troops and support available,
. time available, and
. civil considerations.


The default scoutship is a legacy design from Classic, but may also be one twelve centuries prior to the present era and doesn't reflect current needs and capabilities.
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Re: Ship Design Philosophy

Postby Condottiere » Mon Jan 21, 2019 1:29 pm

Starships: Hulls and Space/balls

18. Light hulled planetoid of ten tonnes has eleven and a quarter hull points.

19. It also has a default cost of thirty thousand schmuckers.

20. An airlock would have a default size of two tonnes, though I would assume it is possible to make amore tighter airlock.

21. A door doesn't take up space; I think it would be a plug, like an airliner, pressure differential wouldn't allow it to open unless it's equalized.

22. A hatchback or a cargo hatch would make it easier to load cargo; you could also embed the plug door in it.

23. A docking clamp would allow an external cargo load, as well as hook up to a larger hull, optionally in assault mode.

24. Adding twelve factors of armour plating displaces nine hundred and sixty kilogrammes, and cost twenty eight thousand eight hundred schmuckers, for a total fifty eight thousand eight hundred schmuckers - which is a bargain.
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Re: Ship Design Philosophy

Postby Condottiere » Tue Jan 22, 2019 12:22 pm

Starships: Hulls and Space/balls

24. A six and a half metre tall beach ball is hard to hide, though they are ubiquitous enough in the Confederation that they're used as armoured fighting vehicles.

25. If you have the default central deck, the door is going to be about two metres off the ground.

26. A two metre ladder is going to be needed, unless you have a two metre high ramp or platform.

27. Specific ones catering to space/balls could be called cup holders, or ball holders, or jock straps.

28. You could tilt the space/ball at thirty, fort five or ninety percent degrees, to position the door closer to the ground, or just drop off the personnel directly; of course, the pilot should be strapped in.

29. The ladder could made of rope or be collapsible; you could also rappel down, or have a winch act as an elevator.

30. If a lifter is installed (and it should), at default it would require one power point and a hundred kilogrammes of volume.

31. At higher technological levels, a higher factored lifter would also act as propulsion, probably in addition to any dedicated thruster.
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Re: Ship Design Philosophy

Postby WingedCat » Thu Jan 24, 2019 4:48 am

If you're looking for a space ball, I wrote one up here.
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Re: Ship Design Philosophy

Postby Condottiere » Thu Jan 24, 2019 10:48 pm

Hi,

a. The principle is the same, however:
i. going by Fire Fusion Steel, the rule of economies of mass meant that fourteen cubic metres was required to obtain default energy output from the power plants, something not mentioned by the current High Guard
ii. flattened sphere probably was subsumed into streamlined configuration

b. currently, spheroids are the most viable choice balancing performance against price

c. a sculpted planetoid in no way either gets benefits or disadvantages from being configured as such; the easiest way would be an Apple brick with rounded corners

d. however, the spheroid shape is to ensure any argument regarding twenty percent wastage, which I presume is to maintain structural integrity, in that it cannot be reshaped is removed, as no one can argue against the perfect symmetry demonstrated by the sphere and it's inherent strength

e. it should be obvious that this is a proxy to explain why the Confederation suddenly massively switched to planetoid spaceships

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