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Re: Miscellaneous Loroi question-and-answer thread
Posted: Sun Oct 06, 2019 7:08 pm
by MBehave
Thats the main engines which you have stated is directional and the ships are slow to turn... why I was asking what their maneuvering thrust is.
I'm trying to work out effective range for high velocity bust railguns using hydrogen pellets for a fleet battle sim.
As the fleets are closing on each other they only really have lateral thrust to use for avoiding incoming fire since the turn rates for the ships are slow.
Arioch wrote:MBehave wrote:15g has a displacement of 73.5m over 1 second, velocity is relative and completely irrelevant, a ship capable of thrust at 15g in any direction will have a sphere of uncertainty with a radius of 73.5m over its previously predicted location.
Volley fire with a bracketed target could be say 3000 kinetic rounds spaced 250m apart against a Umiak Super Heavy.
The
Scimitar has a maximum acceleration of 30
g, so the value would be 147m in one second. But for kinetic rounds to arrive with a delay of only one second, the firing ship would have to be at extremely close range. The AMM-250 at 400
g can only displace about 7,000 km in one second, unless the firing ship had a very high additional relative velocity.
MBehave wrote:The difference in tech level between the Historian and Loroi almost appears greater then the tech difference between the Terrans and Loroi/Umiak, when Umiak invaded historian space did they actually hit any worlds and recover tech databases or ships?
Seems like even a Historian cargo transport would boost significantly the tech level of the Umiak assuming they could understand it.
The Loroi have very little information about what happened in Historian territory during the Umiak invasion. The Historians appear to have withdrawn from the attacked systems having offered very little resistance, and then retook most of the systems less than a year later, but it's not known what the Umiak found there or what they did during the time those systems were under their control. To this point there has been no indication of a spike in Umiak technology, and when pressed on the subject the Historian envoys would say only that it was not a matter of concern.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Sun Oct 06, 2019 11:17 pm
by icekatze
hi hi
Railguns continue to not be very combat effective weapons in the Outsider universe. (Or really any universe with effective beam weapons.)
Also, closing vessels don't need to have their main engines pointed in the axis of movement, they could rotate off axis and still close with their initial momentum.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Sun Oct 06, 2019 11:54 pm
by Arioch
I was able to find the calculations that I did regarding pivot rates and angular momentum, and they give very different pivot rates to the ones in the combat sim -- a 60 degree pivot using differential thrust of the main engines alone was calculated at 3.27 seconds for the
Scimitar and 4.4 seconds for the
Tempest. I don't recall whether I used different values in the sim because I found these to be wrong, or whether I was just fudging for the sake of the Attack Vector sim mechanics (this is from 2005). Here are my notes if you want to check the logic:
1 radian is essentially one 60 degree hex face (57.2958 degrees).
For a test, we’d like to know how long it takes for a cylinder of arbitrary dimensions to rotate 1 radian.
So the angular displacement (theta) we’re looking for is 1 rad in 80 sec. Theta = theta0 + ωt.
On a sample cruiser, F = ma, and a = 294 m/s², and m= 350 kt, so F = 102,900,000,000 N. That’s 51,450,000,000 from each engine (F = ma/2).
Torque = force * distance from center of rotation = τ = F*r. For the cruiser, r is about 115 m. So torque is 5,916,750,000,000 Nm.
Let’s pretend the cruiser has a mass distribution of a sphere. I = 2/5 mr² = 2/5*350kt*(417m/2)² = 6,086,115,000,000 kg*m².
Torque is also equal to the Moment of Inertia * angular acceleration (τ = Iα). So α = τ /I = .97 rad/s².
Θ = ½αt². So the rotation in 1 segment is = .97*(80)²/2 = 3104. That’s 177,859.2 degrees, or 494 complete revolutions. Doesn’t sound quite right.
Let’s look at it going the other way. Looking for a Θ of ½ rad (0.52) in 40 seconds (this would be a maneuvering thruster rate), α = 2Θ/t² = 0.00065 rad/s².
τ = Iα = 6,086,115,000,000 kg*m² * 0.00065 rad/s² = 3,955,974,750 Nm.
F = τ/r = 34,399,780.43 N.
a = F/m = 0.098 m/s² = 0.010 G. So the maneuvering thrusters’ acceleration would be .01 G (or .002 (1/500) thrust points). At the system level, this won’t get you anywhere in a reasonable period of time (after one whole day of thrust, you’ll have yourself 2/500 hex/turn of velocity), so you’re effectively crippled if you lose your main drive.
Let’s assume a worst-case moment of inertia, where all the mass of the ship is at 1/2length (208.5m), so I = mr² = 350kt*(208.5)^2 = 15,215,287,500,000. That’s only about twice as much as the previous example. a = t/I = .3889 rad/s/s. Theta = .3889/2*(80)^2 = 1,244 rad = 198 rotations.
Okay. So the total amount of time to rotate 1 hex face and stop (take ½ radian and multiply the total time by 2) = t = 2*sqrt((theta/2) / (.5*alpha))= 2*sqrt(.52 / (.5*.3889)) = 3.27 seconds.
Let’s try the example for Tempest. Here the mass is 1,200 kt, length is 750m, and the axis of thrust is about 200m. The force of one engine is = 1,200kt*298/2 = 178,800,000,000 N. The torque is 35,760,000,000,000 Nm. The worst-case moment of inertia is = 1200kt*( 375^2) = 168,750,000,000,000. So alpha = .212 rad/s/s. t = 2*sqrt(.212) =
.52 rad = ½ * .212 rad/s/s * t²
.52 rad / (½ * .212 rad/s/s) = t²
sqrt(.52 rad / (½ * .212 rad/s/s)) = t
t = 2.2 s. So that’s 4.4 seconds to complete a pivot of 1 hex face.
2 hex faces = 2*sqrt((2.094/2) / (.5*.212)) = 6.28 sec.
3 hex faces (180 degrees) = 2*sqrt((3.14159/2) / (.5*.212)) = 7.7 sec.
The acceleration potential of the maneuvering thrusters is probably somewhere between .01-.1
g, which won't displace the ship in any kind of meaningful time that would let you dodge shots. The maneuvering thrusters are for rotating the ship and doing fine maneuvers such as docking, not for lateral acceleration.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Mon Oct 07, 2019 2:06 am
by kiwi
icekatze wrote:hi hi
Railguns continue to not be very combat effective weapons in the Outsider universe. (Or really any universe with effective beam weapons.)
Also, closing vessels don't need to have their main engines pointed in the axis of movement, they could rotate off axis and still close with their initial momentum.
Yeah, the projectile speed vs beam speed comparison is pretty damning. I can see two very small niches where railguns could plausibly kick arse:
- Ridiculously close range, where solid projectiles may be better at getting energy through armour. (Assuming armour has been optimised against beam weapons.) Not sure how you get that close without dying first...
- Ridiculously long range bombardment of “stationary” targets (I.e. targets on highly predictable trajectories). I assume you could design a sabot launcher which kept the projectile cold (so it doesn’t shine out obvious infrared) and an active terminal guidance suite in to give a couple of gentle nudges in flight.
Both of these are
very niche.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Mon Oct 07, 2019 8:53 am
by MBehave
Actually I was talking to a guy from CERN on hardscifi discord a few days ago.
Think it deserves its own topic so I will continue this conversation there.
But the gist is.
Its easier to accelerate smaller objects then it is to accelerate large projectiles to large energy levels, peak field strength needed to accelerate something like a 2m long 8cm wide tungsten projectile(outsider Terran kinetic projectile mass) is far greater and less efficient then a vastly smaller encapsulated solid hydrogen pellet due to field dropoff over distance. Railguns should attempt over 4000km/s and use hydrogen pellets.
Such weapons if they fire in bursts are effective at outsider combat ranges and beyond when used to fire in volleys and fleets/guns are linked by firecontrol systems.
They also don't use significant amounts of mass.
icekatze wrote:hi hi
Railguns continue to not be very combat effective weapons in the Outsider universe. (Or really any universe with effective beam weapons.)
Also, closing vessels don't need to have their main engines pointed in the axis of movement, they could rotate off axis and still close with their initial momentum.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Wed Oct 09, 2019 12:52 am
by Dahak
icekatze wrote:hi hi
Railguns continue to not be very combat effective weapons in the Outsider universe. (Or really any universe with effective beam weapons.)
There is a reason that the railgun attacks in the Helfort's War books consisted of firing conical spiral bursts (Swarms) of a hundred thousand or so projectiles plus a liberal supply of decoys to minimise the targets ability to use beam weapons to deflect shots or manuever to face low density areas of the swarm.
And then are happy with three or four hits in 96,000 projectiles.
IIRC they are firing at comparatively very low ranges there and have lower acceleration given Helfort survives trailing behind his ship on a cable at one point while it is evading at one point.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Wed Oct 09, 2019 9:26 pm
by icekatze
hi hi
I don't think 3 or 4 hits is going to do much against anyone who has some moderate understanding of how to make hypervelocity resistant armor. Between whipple shields and appropriate sloping, it can take quite a few hits do cause significant damage.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Thu Oct 10, 2019 5:44 am
by MBehave
A Whipple shield is not magic.
5gram projectile moving at ~18000km/s for example will collapse it and at best still deform the hull, at worst punch through anyways now as super heated plasma.
Can't Reach those speeds in outsider?
This is the velocity off modern day gunpowder weapons vs a Loroi fleet that decided to "charge" Earth.
A perfectly aligned jump with Earth and 4.5au under full thrust at 24g in a flyby attack puts them at 18000km/s
At these speeds ~32000 rounds spaced 50m apart have an effective range against a dodging Loroi Tempest(4.7s 90 degree rotation at 25% lateral acceleration, then 100% lateral acceleration at full thrust)
over 1200000km.
What if we want to waste a million rounds against such a ship at say 20m spaced, effective range of almost 200000km.
Even Earth today could easily handle sending a swarm of BILLIONS of 50 cal rounds, only accuracy is a problem, advanced railguns 160 years down the line designed for space combat should not have that issue.
Of course the launchers would be overtaken by the Loroi fleet shortly after fireing but its just an example of how both projectile and ships speed is important
.
Railguns are not a fleet to fleet weapon unless you can get decent fractional C, they do however work against a high thrust ships by forcing them to burn fuel dodging or limit their maximum system speed. Further if the projectiles are small enough and coated so they are hard to detect fleets have to assume they are underfire and constantly make vector changes further reducing their acceleration ability in straight lines even over short distances.
Rapid fire railguns at Terran outsider speeds of 400km/s with say 1 gram projectiles would significantly limit the intersystem speed hostile fleets ability to charge/retreat under full thrust.
Also ammo is not a problem.
lets say 10000 rounds a minute per gun, after 24 hours of constant use such a gun would only consume 14.4 tons of ammo.
So its not even excessive for a Terran Cruiser to fire constantly for days at a Enemy fleet with such guns just to keep them having to burn reaction mass even if they don't get a single hit.
icekatze wrote:hi hi
I don't think 3 or 4 hits is going to do much against anyone who has some moderate understanding of how to make hypervelocity resistant armor. Between whipple shields and appropriate sloping, it can take quite a few hits do cause significant damage.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Thu Oct 10, 2019 6:09 am
by icekatze
hi hi
Stationary defenses are already regarded is not very effective in the Outsider universe. The ability to maneuver is very important, and if an attacking fleet is able to fly directly toward your planet without being interdicted, you've already lost that engagement whether you have some out of setting railguns or not.
MBehave wrote:A Whipple shield is not magic.
I think everyone can agree on this. I don't think that was ever a question.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 4:40 am
by SaintofM
I guess this is more a human question, but will there be anything in the Loroi diet that Alex can find edible, or if that is a spoiler, what that he has tried to eat can be eaten and kept down to some success?
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 7:53 am
by Arioch
SaintofM wrote:I guess this is more a human question, but will there be anything in the Loroi diet that Alex can find edible [...] ?
Yes.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 8:53 am
by kiwi
Hmm. I think our host said something like "food will be found from an unexpected source," and that telling us would be a spoiler.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 8:59 am
by boldilocks
"Enzin, I'm afraid we're down to testing your ability to consume our least desirable foodstuffs. I'm sorry, but do you think you could stomach nothing but Lobster and Caviar for the next few months? If not, I'm afraid Veal and Foie Gras is all we have left."
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 11:04 am
by Werra
My money is still on Tempos private rations.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 12:22 pm
by Krulle
kiwi wrote:Hmm. I think our host said something like "food will be found from an unexpected source," and that telling us would be a spoiler.
Maybe I'm thinking too close to Rule 34, or "fanservice", but aren't the Loroi mammals?
Otherwise, I am also on Tempo's private stash.
[edit]If the order of my two comments here are connected, that's in your mind only. I only saw it after posting, hence the edit.[/edit]
Seeing that the Loroi are genetically engineered, I presume they can stomach a much larger variety of food, and gain nutrients from stuff poisonous to us.
I don't think there's anything a Loroi couldn't eat (for biochemical reasons) that we Humans could digest.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 1:29 pm
by Werra
It would be a really big spoiler if Alex could eat Barsam food.
It would also disappoint lots of readers. Well, unless the special dietary habits of the Barsam come into play.
Alex will get buff with all that protein.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 5:20 pm
by Roeben
I'm going to presume that the most nutritiously valuable food for Alex will end up being the Loroi equivalent to Mustard or Ketchup.
Either that or some kind of tuber that the loroi consider highly toxic.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Fri Oct 11, 2019 10:16 pm
by kiwi
Roeben wrote:I'm going to presume that the most nutritiously valuable food for Alex will end up being the Loroi equivalent to Mustard or Ketchup.
Either that or some kind of tuber that the loroi consider highly toxic.
I'm going to spend all day trying to come up with sauce puns now.
In the mean time:
A: "Oh no! Captain Jardin drank all the Emperor's Wow-Wow sauce."
B: "How anyone can like that paint stripper is beyond me. Wait. Did you say
drank?"
A: "Yes. Even the new shipment which still had sweat condensing on the bottles. And then he asked for an activated carbon briquette to 'settle' his stomach."
B: "We need to call Damage Control
right now."
Re: Miscellaneous Loroi question-and-answer thread
Posted: Sat Oct 12, 2019 3:30 am
by orion1836
Krulle wrote:kiwi wrote:Hmm. I think our host said something like "food will be found from an unexpected source," and that telling us would be a spoiler.
Maybe I'm thinking too close to Rule 34, or "fanservice", but aren't the Loroi mammals?
Otherwise, I am also on Tempo's private stash.
He finds out that Umiak taste like lobster when you take out the cyborg bits.
Re: Miscellaneous Loroi question-and-answer thread
Posted: Sun Oct 13, 2019 3:00 am
by Murph
It is going to be something....interesting I suspect.