Ship Design Philosophy

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

Postby darue » Thu Nov 14, 2013 2:48 am

ok, imagine the Type-S is way out in space (not in a gravitationally bound system like an orbit)

it gives itself a little rotation to the left, say starting out at 1 degree per sec, then kicks in the M-drive (thrust vectored to aft) at some acceleration. some rate of rotation to the left will match Speed such that it's able to go in a circle. but the acceleration keeps the speed going up, so the rate of rotation to the left has to go up to keep the motion circular and of constant radius, but eventually the centripetal acceleration will be greater than the thrust, and the radius will start slipping, getting bigger as the thrust isn't enough to compensate. and in a type-s that would be at 2gs. So ok, I think I now agree that loose non-inertialcompensated crew would only ever feel 2gs, since there's nothing to constrain it's motion. Now if you tied the same type-s to an immovable object with an unbreakable string, the same crew could be smeared onto the wall once the speed gets fast enough.

thanks for helping me get that off my mind :lol:
phavoc
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Re: Ship Design Philosophy

Postby phavoc » Thu Nov 14, 2013 4:59 am

darue wrote:ok, imagine the Type-S is way out in space (not in a gravitationally bound system like an orbit)

it gives itself a little rotation to the left, say starting out at 1 degree per sec, then kicks in the M-drive (thrust vectored to aft) at some acceleration. some rate of rotation to the left will match Speed such that it's able to go in a circle. but the acceleration keeps the speed going up, so the rate of rotation to the left has to go up to keep the motion circular and of constant radius, but eventually the centripetal acceleration will be greater than the thrust, and the radius will start slipping, getting bigger as the thrust isn't enough to compensate. and in a type-s that would be at 2gs. So ok, I think I now agree that loose non-inertialcompensated crew would only ever feel 2gs, since there's nothing to constrain it's motion. Now if you tied the same type-s to an immovable object with an unbreakable string, the same crew could be smeared onto the wall once the speed gets fast enough.

thanks for helping me get that off my mind :lol:
Starship grav plating eliminates the g-forces inside the ship. That's always been true. It used to be the law of the Trav universe that 6G's continual acceleration was the maximum. MgT has sub-100 ton ships being able to do up to 14G's (16 with afterburners), and starships can also now temporarily increase their G-rating beyond 6. I don't recall if the rules were adjusted to handle this. AFAIK there is no penalty to crew on a 14G ship as far as acceleration penalties go.
Condottiere
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Re: Ship Design Philosophy

Postby Condottiere » Thu Nov 14, 2013 8:05 am

Acceleration, G Forces and Human Tolerances


1. A little research shows that a trained, fit fighter pilot in a G-suit can remain conscious at upto 9 gees.

2. Rollercoasters usually don't exceed three gees.

3. You could blackout between four to six gees.

4. Fifteen gees might kill you.
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Re: Ship Design Philosophy

Postby Condottiere » Thu Nov 14, 2013 11:19 am

An interesting entry from Traders and Gunboats, from the Antique In-Systems Hauler TL8.

"They are large, use primitive versions of gravitic drives, and rely on dirty fission powerplants.

Manoeuvre Drive G.7, 26 tons and cost 42 MCr.

Compare to:

Fusion Rocket G, 13 tons and 28 MCr.

Assuming the above isn't a typo, large grav drives are double the size and cost 50% more in comparison.
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Re: Ship Design Philosophy

Postby F33D » Thu Nov 14, 2013 2:26 pm

Condottiere wrote:Acceleration, G Forces and Human Tolerances


1. A little research shows that a trained, fit fighter pilot in a G-suit can remain conscious at upto 9 gees.
Only for a few seconds. It's only counted in seconds for 6 G's...
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Re: Ship Design Philosophy

Postby Condottiere » Thu Nov 14, 2013 4:56 pm

1. Mermaids - female pilots in acceleration tanks. Suddenly Arial seems appropriate.


2. Smallest jump drive.

It's kinda obvious that there five tons added on to each jump drive, though whether it's control panels, shielding or bracing, no idea. A little calculation shows that a commercial run would be 7.5 tons for jump 1 for a hundred ton starship, probably at 7 MCr. A bespoke version might be 6 tons at 12 MCr.

Why a Jump One Drive for a hundred ton ship? A small yacht, with the possibility of insystem jumps, or a business jet. Or even a commuter.
Last edited by Condottiere on Fri Nov 15, 2013 10:52 am, edited 1 time in total.
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Re: Ship Design Philosophy

Postby F33D » Thu Nov 14, 2013 6:15 pm

Condottiere wrote:1. Mermaids - female pilots in acceleration tanks. Suddenly Arial seems appropriate.
That wouldn't help with G-loc. You still experience the acceleration in or out of water.
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Re: Ship Design Philosophy

Postby phavoc » Thu Nov 14, 2013 10:38 pm

F33D wrote:
Condottiere wrote:1. Mermaids - female pilots in acceleration tanks. Suddenly Arial seems appropriate.
That wouldn't help with G-loc. You still experience the acceleration in or out of water.
I think a gel of some sorts would work. Would be messy, but should absorb some of the acceleration.
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Re: Ship Design Philosophy

Postby Condottiere » Thu Nov 14, 2013 11:59 pm

Which begs the question, what's the usual sustained acceleration a trained fit human fighter pilot can endure at six minutes, and for an hour stretch.
darue
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Re: Ship Design Philosophy

Postby darue » Fri Nov 15, 2013 1:20 am

phavoc wrote:
F33D wrote:
Condottiere wrote:1. Mermaids - female pilots in acceleration tanks. Suddenly Arial seems appropriate.
That wouldn't help with G-loc. You still experience the acceleration in or out of water.
I think a gel of some sorts would work. Would be messy, but should absorb some of the acceleration.
well, at that point you'd want to be breathing a hyper-oxygenated liquid too.
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Re: Ship Design Philosophy

Postby F33D » Fri Nov 15, 2013 2:18 am

phavoc wrote: I think a gel of some sorts would work. Would be messy, but should absorb some of the acceleration.
Nope. Unfortunately that wouldn't work. You have to have something that will absorb for longer than a fraction of a second. Which is what padding, of any kind does. Only inertial compensators (Trav magic) works. Just basic physics. The same reason you don't get that weightless (funny stomach falling feeling ) sensation in water (or gel) is the same reason it doesn't work...
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Re: Ship Design Philosophy

Postby phavoc » Fri Nov 15, 2013 3:47 am

F33D wrote:
phavoc wrote: I think a gel of some sorts would work. Would be messy, but should absorb some of the acceleration.
Nope. Unfortunately that wouldn't work. You have to have something that will absorb for longer than a fraction of a second. Which is what padding, of any kind does. Only inertial compensators (Trav magic) works. Just basic physics. The same reason you don't get that weightless (funny stomach falling feeling ) sensation in water (or gel) is the same reason it doesn't work...
I was referring to a gel that would absorb more pressure as it was applied, not like liquid gel soap. I've heard of some seats that have a gel-like substance in them that as you apply more pressure they get harder. It's got something to do with the hydrostatic pressure in the pockets of the material, and that as more pressure is applied, it resists it more. Kind of like you can't compress water. But I'm not a materials science guy, that's the best description I know of for it. I think the usage is because the gel has a curve of sorts in absorbing the force, so it's better than say foam which compresses more.
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Re: Ship Design Philosophy

Postby Condottiere » Fri Nov 15, 2013 7:57 am

1. I recall one Scifi novel where they had spherical interceptors and pilots in acceleration tanks. Probably TL9 setting.


2. Smallest starship fusion powerplant

Again there's some sort of shielding, control panel overhead of a ton, which smallcraft seem to need only 0.9 tons of. The generic version is 2.5 tons and costs 4 MCr. This jives with the smallcraft equivalent sE at 2.4 tons but costing 5 MCr.

Striker and FF&S established economies of scale for power plants; the standard tables veer heavily away from that concept.



3. Bespoke fusion plants.

You'll notice that overhead applies with one percent fixed, plus half a percent for each value, until you reach five where there's a jump of one percent. Interestingly, there's a similar increased difference for fusion rockets.

That would imply that the most efficient values are factor four, which doesn't make much sense.


4. Most efficient smallcraft power plant - sK.

5. Most efficient smallcraft gravitic drive - sK.

6. Most efficient smallcraft rocket drive - sR.
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Re: Ship Design Philosophy

Postby Condottiere » Fri Nov 15, 2013 11:32 am

Austere Pirate Skiff

1. Acceleration nine gees, or ten if the passenger acceleration couch compensates, I forget.

2. Turret, not fixed armament - you may want to shoot while coming and going.

3. Hot bunking in three shifts - I recall you used to be able to squeeze in six bunks in a stateroom, so eighteen maximum crew. Refresher facilities should be sufficient.

4. Low passage berths - for prisoners

5. Crew: pilot, sensor/EW tech, gunner, engineer, medic; eleven boarders.

6. Airlock. Breaching tube, docking clamp, ship's locker optional.

7. Stealth, solar panels.

Thirty tons, sB fusion, sQ rocket, missile launcher.

Squeezing it all in would be challenging, but the most expensive parts of smallcraft tend to be the drives. While the crew size isn't fixed, you do need a pilot, you need someone to detect spacecraft and jam their communications, and you need someone that when shooting doesn't accidentally blow it to hell. An engineer in case you take over the ship.

A more elaborately outfitted boarding craft could be had for upto sixty tons.
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Re: Ship Design Philosophy

Postby F33D » Fri Nov 15, 2013 2:58 pm

phavoc wrote: I was referring to a gel that would absorb more pressure as it was applied, not like liquid gel soap.
Still wouldn't work.
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Re: Ship Design Philosophy

Postby rust » Fri Nov 15, 2013 3:14 pm

phavoc wrote: I was referring to a gel that would absorb more pressure as it was applied ...
While this could reduce some of the unwelcome side effects of a high
acceleration, it would not solve the major problem, which takes place
inside the human body. For example, during an acceleration of 6 G the
blood inside the body moves into one direction with six times the nor-
mal force, which causes severe stress for the heart and the blood ves-
sels.
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Re: Ship Design Philosophy

Postby Condottiere » Mon Nov 18, 2013 7:50 am

1. I still need a guide for:

a. Maximum sustained gee force that doesn't create any medical problems for humans. 1'm guessing between 1.5 to 2.

b. Maximum sustained gee force for around six hours.

c. Maximum sustained gee force for about an hour. I'm guessing three gees.

d. Maximum sustained gee force for six minutes. I'm guessing less than sixteen gees.


2. The definition of fighter could be narrowed to smallcraft that exceed six gees in acceleration.
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Re: Ship Design Philosophy

Postby rust » Mon Nov 18, 2013 10:30 am

Condottiere wrote:1. I still need a guide for:
(...)
The human body is well adapted to a surface gravity of 1 G, any
higher gravity or acceleration causes severe stress for the cardio-
vascular system. For short periods of time and with the best pos-
sible equipment (acceleration seats, g-suits, etc.) an acceleration
of up to 6 G carries only a minor medical risk, but for longer peri-
ods of time even 2 G would be dangerous - the heart and blood
vessels are just not made to do twice their usual job, the risk of
a heart failure or of the rupture of a blood vessel (potentially re-
sulting in a stroke) would increase considerably. So, for six minu-
tes even 3 G would be much, for about an hour 2 G would be much,
and for any longer period of time the acceleration should remain
significantly below 2 G.

Edit.: If you want some more information, you could take a look a
the book "The Biology of Human Survival: Life and Death in Extre-
me Environments" by Claude A. Piantadosi, a professor of environ-
mental medicine at Duke University.
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Re: Ship Design Philosophy

Postby Condottiere » Wed Nov 20, 2013 11:11 am

Compactest Capital Ship

1. Apparently, 2001 tons in two sections

2. Smallest components based on 2050 tons:
a. 2 x 11 ton bridges
b. 41 ton Jump drive factor 1
c. 31 ton fusion power plant factor 1
d. 21 ton manoeuvre drive factor 1, or 41 tons of thruster plates
e. 2 x 100 ton drop tanks (not dropped)
f. Core/3 computer
g. Theoretically, three bay weapons, 28 turrets
h. 1000 tons TL15 Meson A, though I vaguely recall some limitations due to power plant size
i. Crew command 10, 1 or 2 engineers, 7 service
j. Theoretically, 10 spinal, 6 bay, dampers 4, turrets 28

3. 41 ton jump drive
a. jump 1 - 2050 tons
b. jump 2 - 1366 tons
c. jump 3 - 1025 tons
d. jump 4 - 820 tons
e. jump 5 - 683 tons
f. jump 6 - 585 tons

4. 31 ton fusion plant
a. factor 1 - 2066 tons
b. factor 2 - 1550 tons
c. factor 3 - 1240 tons
d. factor 4 - 1033 tons
e. factor 5 - 775 tons
f. factor 6 - 620 tons

5. 21 ton fusion rocket
a. factor 1 - 2100 tons
b. factor 2 - 1680 tons
c. factor 3 - 1400 tons
d. factor 4 - 1200 tons
e. factor 5 - 840 tons
f. factor 6 - 646 tons

6. 41 ton gravitic drive
a. factor 1 - 2050 tons
b. factor 2 - 1640 tons
c. factor 3 - 1366 tons
d. factor 4 - 1171 tons
e. factor 5 - 820 tons
f. factor 6 - 630 tons


Acceleration: Why it is relevant

1. At 10, you could outrun missiles.

2. The faster an assault shuttle lands, the less likely it is to being shot down.

3. Interception of fugitives, or at least getting in range to knock out the engines before they jump.
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Re: Ship Design Philosophy

Postby locarno24 » Wed Nov 20, 2013 2:29 pm

Theoretically, three bay weapons, 28 turrets
Two. A Fusion-1 plant can support one bay weapon per 1000 dTons.

1 Turret per 100 dTons not allocated elsewhere, so 20 less the volume of heavier weapons.

1000 tons TL15 Meson A, though I vaguely recall some limitations due to power plant size
Correct. You need a minimum of a Fusion-2 to support spinal weapons.



In terms of pursuing fugitives; this is one of the only good reasons to take a (non-heavy) missile weapon on a proper warship: the ability to fling a spread of jumpbreaker missiles at a fleeing ship.
Understand that I'm not advocating violence.
I'm just saying that it's highly effective and I strongly recommend using it.

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