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Post by Drahkan on Nov 8, 2016 20:31:20 GMT
Armor: DO NOT use boron in thick layer of more than 1.5 cm or so. Hell, maybe even lower. They turn from okay protection to fragmentation the thicker they go. dragonkidd11, how did you come up with this conclusion? Last night I ran some tests on this theory, basically built a long station that had a column of generators down the middle with crew capsules at each end (plus redundant radiators), slapped varying thicknesses of boron on it, then went at it repeatedly using a single stock 8mm railgun and timed how long it took for it to be disabled. Intercept speed was kept to 50m/s, so the station was definitely destroyed before range started to reduce the randomness of hit locations. After running multiple tests with either 1cm or 4cm of boron armor, the 4cm kept the station alive 50%-100% longer than only 1cm. I forgot to write down the actual numbers and it's definitely far from an exhaustive test, but it seems to indicate that even if spalling is happening with the thicker boron armor, although you may be getting diminishing returns on your investment, unless you're doing some really fancy layering (which perhaps is what your statement is based on?) you're still better off with the extra centimeters.
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Post by shiolle on Nov 9, 2016 8:55:36 GMT
What parameters affect propellant efficiency in an NTR? Is it molecular mass and specific heat? I was recently trying to design a good decane NTR, and I can't get exhaust velocity above 5.5 km/s because I constantly run into problems with control rods melting. Has anyone managed to make a 7-10 MN decane thruster with exhaust velocity comparable to methane NTRs?
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Post by goduranus on Nov 9, 2016 9:12:13 GMT
The exhaust velocity depends on the weight of molecules after they are dissociated. Lower mass molecules is higher velocity. Dissociated decane has more carbon relative to hydrogen than dissociated methane, so decane exhaust velocity is lower.
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Post by dragonkid11 on Nov 9, 2016 11:31:57 GMT
Exhaust speed has a limit depending on what you use.
5.5 km/s is pretty much the maximum limit of decane, while 6.5 something km/s is the maximum limit of methane.
The only way to break that limit is if you have magical nuclear fuel that can withstand stupidly high heat.
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Post by targetx on Nov 9, 2016 17:06:44 GMT
You can get 4.5km/s exhaust velocity with semi heavy water easily, combined with its density at 1100kg/m3 can give you really compact ships with high deltaV. Its my goto fuel now over decane
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Post by shiolle on Nov 9, 2016 19:14:40 GMT
Thank you for your answers. I got interested in decane because it makes for a good fuel for resistojets. I wanted to make a ship with static main thruster that turns using RCS for my experimentation with protecting engines from nuclear blasts. That would allow me to have a single type of fuel onboard. However, I have some unresolved problems with turning such designs, including stock Cutter.
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Post by Drahkan on Nov 9, 2016 22:23:14 GMT
Thank you for your answers. I got interested in decane because it makes for a good fuel for resistojets. I wanted to make a ship with static main thruster that turns using RCS for my experimentation with protecting engines from nuclear blasts. That would allow me to have a single type of fuel onboard. However, I have some unresolved problems with turning such designs, including stock Cutter. Although it appears to have been partially fixed in 1.0.7, there's a bug (of sorts) with using both resistojets and nuclear thrusters on the same ship: regardless of where the resistojets and NTR's are located (be the NTR's at the bottom as expected and the resistojets as RCS thrusters), unless you disable the resistojets, they will be the only rockets that your ship uses for strategic map travel. It used to be that even if you disabled them they would still burn all your fuel, but I just went into the game and tried again and now it appears that I can at least get them to stop burning up all my fuel for long burns. But what happens when you enter combat, regardless of if they are turned back on or not, I know not. (And having to enable/disable them is an accident waiting to happen during the middle of a multiple-combat, multi-hour-scenario, if you ask me.) Qswitched has stated that it shouldn't work that way - rockets at the "bottom of the stack" should take priority - but unless it's something unusual about all of my ship designs, that definitely isn't the case.
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Post by shiolle on Nov 10, 2016 9:06:59 GMT
Here is what I found after some more testing of ships with RCS. - My ships turn on their main engine when ordered to turn in combat, even though it doesn't help the ship to turn at all. I first thought that since the game has to determine the purpose if each engine on its own, it would determine which engines actuallyhelp with the desired maneuver, but it doesn't seem to be the case.
- You have to have enough power on board to be able to power half of all your resistojets at once, for ibvious resons. For example, if you have twelve 3MW resistojets as RCS, you will need at least 18 MW if power or your RCS won't be useful at all. It seems that the bug that allowed you to continuously power any number of electric propulsion thrusters as long as youhad enough power for one has been fixed.
- I saw some strange behavior as my ships turned. I expected to see one half of resistojets turn on and the ship to start rotating at an increasing rate, then halfway through the turn another half of RCS thrusters turn on and the ship rotation slows down until it faces the desired direction. Instead I saw the ship using the same set of thrusters throughout the turn, and they would flicker as if turning on and off, even though there was enough power for them. The rate of turn looked constant even though the rssistojets were thrusting. I will need more experiments to verify it.
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Post by fallingaggressively on Nov 10, 2016 10:03:08 GMT
I think that pulsing of the RCS is due to the PID being used to control the RCS is setting its target too low which causes the control value to oscillate around the target value because of either overcompensation or lag in the control response. I'm probably explaining that really badly but its something along those lines.
It basically boils down to PID tuning being hard to do properly.
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Post by Drahkan on Nov 11, 2016 0:14:17 GMT
Thanks to the current state of "rocket code", whatever primary rocket type I use for my main engines, I also put a single one of them on the front/top of my ship as well. (I put my engine cluster in the middle of my ship, opposite my "citadel armor" which is only 50% radius and just blocking said middle section, making them kinda look like a "flying banana.") Which, really, I just did because I couldn't get RCS/resistojets to work. ...although it DOES work really well. My armada of Flying Bananas lays waste to my foes.
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Post by shiolle on Nov 11, 2016 7:02:17 GMT
I think that pulsing of the RCS is due to the PID being used to control the RCS is setting its target too low which causes the control value to oscillate around the target value because of either overcompensation or lag in the control response. I'm probably explaining that really badly but its something along those lines. It basically boils down to PID tuning being hard to do properly. Whether it's PID or something else, it seems that deceleration is instant. After observing more of this behavior, it looks like this. The ship starts to turn at an accelerating rate but when its angular velocity hits a certain threshold, opposite thrusters activate for just a split second which immediately stops the ship (the ship has just spent at least two seconds accelerating). It then tries to accelerate again, and is stopped again. This results in an exorbitant waste of fuel and very slow turning. If it was just the control algorithm trying to compensate too early it wouldn't cancel velocity instantly. Also, I switched from resistojets to chemical rockets for RCS. Resistojets with enough thrust to turn even my fairly light ship quickly enough either use too much power or are too inefficient. Since I don't want to use powerplants in 100 MW range on every ship, using methane NTR main thruster and methane-LOX RCS thrusters seems reasonable. P.S. Why do you think it is controlled by PID? I mean, the transfer function is known in this case, and it is perfectly accurate since it is used for simulation.
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Post by fallingaggressively on Nov 11, 2016 13:10:25 GMT
Two reasons why I think its a PID. First is that they are a great tool for a control system. Second is that I tried to create a space battle game and that is a behavior I observed. I got around it by cheating and giving up on some authenticity...
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Post by tessfield on Nov 12, 2016 17:10:08 GMT
On the Ship Designer, when moving radially attached modules, the position of a module is updated only when the mouse pointer moves 1px on either X or Y direction, and the amount of movement is calculated based on the angle to the ship's main axis. (I'm probably not explaining this very well). Point being, if you move your mouse only horizontally (assuming the ship is pointing vertically) the module will move very little, while if you move your mouse only vertically (again, assuming the ship is pointing vertically) the module will move a lot.
tldr; Move the cursor horizontally on the Ship Designer screen while holding a radially-attached module for higher precision.
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Post by tessfield on Nov 12, 2016 23:49:08 GMT
If you add a remote control module to a crewed ship, you retain control of the ship after all crew modules have been destroyed.
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Post by Drahkan on Nov 13, 2016 21:33:26 GMT
If you add a remote control module to a crewed ship, you retain control of the ship after all crew modules have been destroyed. Oh wow, really? That's brilliant! Does it affect what "type" of ship it is, however? (As in, does it still end up in the "warship" section and work "as usual" in the game?)
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