Xenon Bigger Containers

[juvilado]

Hi, first of all, i dont know if this has been already suggested, anyway ill do:

It could be sometimes useful to have a big xenon container, not for tiny ships of course, but for "motherships" with a small manned Xenon probe.

Take for instance an ambitious manned mission to Jool system with the purpose of landing in as many moons as possible and then return to the mothership. For the lightest moons, it would be possible to use a xenon powered lander that later returns to orbit. It could then be refuelled with the Xenon of the mothership, stored in a big container, which is why im making this post. Agree, we can still use lots of smaller ones, but i think a big one will perfectly fit in the game.

What do you think? Will it be added in the next update ?

Edited September 26, 2014 by juvilado

[MKI]

First off there needs to be bigger Xenon Engines to warrant bigger Xenon fuel tanks. Yes it fits for a "mothership" idea, but outside of that its pretty impractically. Any sort of Xenon only propulsion ship couldn't afford to push a large Xenon container.

It also isn't exactly necessary to throw in more than 2-3 xenon containers on the mother ship and you should be fine. Xenon runs so efficiently i doubt you would use up all the Xenon on the probe every mission.

[Stratzenblitz75]

Hi, first of all, i dont know if this has been already suggested, anyway ill do:

It could be sometimes useful to have a big xenon container, not for tiny ships of course, but for "motherships" with a small manned Xenon probe.

Take for instance an ambitious manned mission to Jool system with the purpose of landing in as many moons as possible and then return to the mothership. For the lightest moons, it would be possible to use a xenon powered lander that later returns to orbit. It could then be refuelled with the Xenon of the mothership, stored in a big container, which is why im making this post. Agree, we can still use lots of smaller ones, but i think a big one will perfectly fit in the game.

What do you think? Will it be added in the next update ?

The Xenon tanks we already have are large enough for ion landers; I only used 15 small radial tanks (8.5 stack mounted tanks) to supply my ion lander with enough fuel to land on every planet (except, Eve, Moho, Vall and Tylo). As MKI stated, you should only need like 2-3 containers for just the Jool System.

If perhaps larger Xenon engines are added then yes, larger tanks would be useful, but as it stands, we don't need them.

[juvilado]

Well, making a bigger one wouldnt hurt anybody though...

[Tex_NL]

In the mean time you could use [thread=80234]TweakScale[/thread]. With this mod the regular Xe tanks can be resized all the way up to 5m, resulting in more dV you know what to do with.

[juvilado]

In the mean time you could use [thread=80234]TweakScale[/thread]. With this mod the regular Xe tanks can be resized all the way up to 5m, resulting in more dV you know what to do with.

Didn't know that mod, thanks!

[Justin Kerbice]

In the mean time you could use [thread=80234]TweakScale[/thread]. With this mod the regular Xe tanks can be resized all the way up to 5m, resulting in more dV you know what to do with.

But it needs some tweaking as default settings lead to unbelievable dry mass of the resized tank (a lot more than a JB64 !)

[Monthar]

I don't think we need bigger ion engines to warrant larger tanks. Yes, we can put more tanks on if we need more fuel. However, as more parts are added the slower the game runs. Therefore, by having some larger tanks we can get the same amount of xenon with fewer parts, thus less memory drain, fewer connection points to break/flex, etc. making the game run better.

Along these same lines, I think we could also use some 2x2 and 1x6 and 2x3 versions of the first solar panel and perhaps some wings that have built in solar panels. Then we can have a means to generate power while moving in the atmosphere while trying to keep the weight down. The fold out panels are nice, but they break if used in the atmosphere and the RTGs only generate the same power as the basic solar panel but weigh a lot more. Again, this is to cut down on the number of parts needed.

Edited September 27, 2014 by Monthar

[juvilado]

Totally agree with Monthar

[Sean Mirrsen]

You might want to check out the Near Future Technologies mod. Among (a lot of) other things, the Propulsion pack in particular adds a whole host of new ion and plasma engines, using Xenon, Argon, and Hydrogen fuels. And it has inline and radial Xenon tanks of many sizes.

Not to mention the various solar panels of the Solar pack, the capacitors and reactors of the Electric pack, etc. It's really a mod worth checking out.

[Red Iron Crown]

If you are open to mods, Modular Rocket Systems has some larger xenon tanks, along with other parts to fill in some gaps in the stock lineup.

I definitely agree that bigger xenon tanks would be useful. Any non-probe-sized ion ship ends up with a pile of tiny tanks. I am surprised by the assertion above that 15 tanks for a lander is reasonable, 3-4 tanks should be enough parts to keep an engine fueled.

[KerikBalm]

This is super easy to do by yourself.

Example:

PART

{

name = xenonTank125

module = Part

author = Whatever

mesh = model.mu

scale = 1

rescaleFactor = 2.0

node_stack_top = 0.0, 0.1404661, 0.0, 0.0, 1.0, 0.0

node_stack_bottom = 0.0, -0.1404661, 0.0, 0.0, 1.0, 0.0

TechRequired = ionPropulsion

entryCost = 8800

cost = 800

category = Utility

subcategory = 0

title = PB-X1500 Noble Gas Container

manufacturer = Probodobodyne Inc.

description = A large cryogenic container for inert gases such as Xenon, Argon, Helium, etc.

attachRules = 1,0,1,1,0

mass = 0.0625

dragModelType = default

maximum_drag = 0.2

minimum_drag = 0.3

angularDrag = 2

crashTolerance = 6

maxTemp = 2900

breakingForce = 50

breakingTorque = 50

RESOURCE

{

name = XenonGas

amount = 5000

maxAmount = 5000

}

}

Use the same model and mbm files as the stock xenon tank, add in the rescale factor line.

Tweak as desired

[juvilado]

ive never done this before, but is worth a try...

[Jouni]

Bigger xenon tanks and bigger ion engines would make nuclear engines obsolete, except as lander engines.

My old Moho mothership had an almost reasonable TWR with 12 ion engines and 60 xenon tanks. If part count were not an issue, I would have started using the same design in all of my interplanetary ships. The performance was just superior to everything else. It was almost like having jet engines in space.

[juvilado]

Well, the question then is: Is it possible to build real world bigger ion engines? Would they be reasonabily efficient?

It could be a more advanced technology to be researched with more science points

[Jouni]

Well, the question then is: Is it possible to build real world bigger ion engines? Would they be reasonabily efficient?

Real ion engines would require much more power than the ones in KSP, while having something like 1000x lower TWR. The engines we have in the game are what they are due to gameplay reasons, and scaling them up would just make them even more ridiculous.

[Sean Mirrsen]

Like I said earlier, you should try the Near Future Technologies mod. Lots of large electric engines there, with appropriately large power requirements. The mod even scales the PB-ION back to its pre-buffed state, to keep the new electric engines balanced.

[Jouni]

Like I said earlier, you should try the Near Future Technologies mod. Lots of large electric engines there, with appropriately large power requirements. The mod even scales the PB-ION back to its pre-buffed state, to keep the new electric engines balanced.

Balanced perhaps, but not appropriately large. If we take the VASIMR as an example, ion engines need about 40 MW of power to generate 1 kN of thrust. That's around 0.1 km^2 of solar panels at 1 AU, or a nuclear reactor with a few hundred tonnes of mass.

[Sean Mirrsen]

Appropriately large, not realistically large. Almost nothing in KSP is realistically large.

[Jouni]

Appropriately large, not realistically large. Almost nothing in KSP is realistically large.

Appropriately large would mean that the engines fit the same niches as in the real world. For example, ion engines would be too weak to land on Gilly.

[Sean Mirrsen]

That would still be realistic, since you measure against the real world. By the same metric, turbojets and bell thrusters should be too inefficient to create working single-stage-to-orbit designs, and yet here we are. And any burns using the PB-IONs would take real-time months.

Like I said, almost nothing in KSP is realistically scaled. The electric engines in NFT are scaled to the original implementation of the PB-ION, but are using a different balancing metric. They're not balanced against the rest of KSP, they're balanced with regard to technological progress, and their power consumption is dictated first and foremost by internal balance within the mod, not within KSP. Stock KSP barely factors into it. So, appropriately large power consumption and performance. Not realistic, because nothing in KSP is. Not balanced, because current KSP balance is a sandbox of similarly useful parts and NFT implies a technological progression to more efficient engines. But it's appropriate, because it takes an existing part as a starting point and tries to stay within reasonable bounds with regards to both realism and stock balance (i.e. no Q-thrusters just yet, and engine performance is upgraded from real life in the same way the PB-ION's initial version was).

It's really quite a fine mod.

[Monthar]

Bigger xenon tanks and bigger ion engines would make nuclear engines obsolete, except as lander engines.

My old Moho mothership had an almost reasonable TWR with 12 ion engines and 60 xenon tanks. If part count were not an issue, I would have started using the same design in all of my interplanetary ships. The performance was just superior to everything else. It was almost like having jet engines in space.

I can see bigger ion engines making the nuclear engines obsolete. Bigger xenon tanks however would not. The entire point of this thread is about bigger tanks not bigger engines.

Currently we have 2 tank sizes for xenon, but if you look at every diameter of LFO tank and you'll see up to 4 different lengths of the inline tanks. We have only 1 length of the inline xenon tank and 1 side mounted tank that holds even less. We also have adapters to allow running 1-4 engines on a single LFO tank. So it's no unreasonable to have large enough xenon tanks to allow running 1-4 ion engines off them.

[Jouni]

Not realistic, because nothing in KSP is.

This is where you are wrong. KSP is realistic game that's explicitly marketed as a realistic game. Realism, on the other hand, doesn't mean that everything works in the same way as it works in the real world. It means that the game is isomorphic to the reality. If you take a real mechanism and map it into game terms, the important parts of the mechanism should still work qualitatively the same way. Similarly, if you take a game mechanism and map it into real-world terms, the important parts should remain qualitatively the same.

KSP rockets are mostly realistic. The biggest difference is that atmospheric pressure affects fuel flow instead of thrust. There are also lesser issues, such as engine restartability, perfect reliability, and the exact properties of fuels, which may or may not be significant, depending on the player. Some systems, such as reaction wheels and fuel lines, are also unreasonably efficient.

Aerodynamics and atmospheric reentry are broken, but they're obviously placeholders that will probably be improved in the future.

Orbital mechanics are mostly correct. The patched conics approximation breaks down near the inner moons of Jool, but otherwise it works fine. Some people might complain that orbits remain stable without stationkeeping, but it's a minor issue.

The solar system could not exist as such, so it's better to think it as a bigger system scaled down for player convenience. This has two major unrealistic consequences. The delta-v requirements for reaching orbit are so low that single-stage rockets can lift useful payloads. For a similar reason, interplanetary ships can just cruise around without dropping stages.

Jet engines are broken in every conceivable way. Surely they take something from the atmosphere to burn the fuel, but apart from that, they don't resemble real jet engines in any way.

Ion engines are a mixed case. Even though they are four orders of magnitude more power-efficient than real engines (1000x thrust for 1/10 of power), their performance is similar to real engines, as long as they're used only for orbital maneuvers and interplanetary transfers. As soon as you put them in landers, they become magic technology with no basis in reality.

I can see bigger ion engines making the nuclear engines obsolete. Bigger xenon tanks however would not. The entire point of this thread is about bigger tanks not bigger engines.

Bigger tanks would actually have more impact. Currently you need one ion engine per 1-2 tonnes of payload to get TWR up to useful levels. As most interplanetary payloads are at most tens of tonnes, the engines don't increase the part count or the complexity of the ship significantly. On the other hand, you need 5-10 xenon tanks per engine to get the delta-v figures to similar levels as with nuclear engines, which becomes a significant burden with bigger ships.

[Monthar]

I disagree. You'd still have the same total mass from the tanks and the amount of xenon they hold. The only difference between bigger tanks and multiple small tanks would be the part count, which means the game will run smoother as it wouldn't need at much memory for that ship. By your logic, we don't need multiple lengths of the LFO tanks either, because the shortest one for each diameter is good enough as long as we stack several of them.

Edit: I decided to add some screenshots to demonstrate my point.

Nuclear engine with the tallest of the LFO tanks of the same diameter as the engine.

Nuclear engine with 8 of the shortest LFO tanks of the same diameter as the engine.

Notice how in both cases you have the same total mass and delta-v. The difference being the part count jumped from 3 to 10.

To compare with the nuclear engine here is an ion engine with enough tanks to exceed the delta-v of the nuclear engine from the previous screen shots, along with the minimum number of fold out solar panels to power this one engine. This also take 10 parts, but you'll notice even though it has significantly less total mass it also has a significantly lower thrust to weight ratio, so you're going to have to burn the engines for much longer to reach the same speed/course change.

Also note, that if using the small flat solar panels (first one unlocked), you'd need 12 of them instead of 5 of the fold out panels thus increasing the part count by another 7 parts for a slight decrease in total mass. If you went with RTGs so you could run the ion engine when on the night side of any of the planets/moons it would also take 12 of them which would increase the total mass of the ship. However, after replacing solar panels with RTGs you have to add 2 more inline tanks to have slightly less (40 less) delta-v than that of the nuclear engine ship from the first two screenshots, but still less than the first ion engine ship's screenshot. That raises the total mass of the ship by approximately 72% over what it is with the 5 fold out solar panels. The extra fuel and tanks of course increases the total mass even more and raises the part count to 19. See the next screenshot.

It would take 19 ion engines on the ion ship to equal the vacuum thrust to weight ratio of that nuclear engine ship. That's only if the total mass of the ship remained the same. However since the mass will increase just from adding the extra engines. then you have to also add the extra power generation from RTGs or Solar Panels to power them all. Since you can't mount an inline xenon tank on the side of another inline xenon tank you have to add cubic-octagonal struts to mount the extra ion engines. Luckily you don't need to run fuel lines to them. Here's an example with just adding 6 more ion engine, the extra RTGs to power them and the extra tanks to have a similar delta-v and it only doubled the thrust to weight ratio of the single ion engine ship. This increased the part count to 133 and total mass to almost double that of the nuclear engine ship. If you're playing in Career mode where you have to worry about costs, it costs more than 35.5 times as many Kerbucks as the 3 part nuclear engine ship.

Therefore, no matter how you look at it, there is absolutely no way adding some larger xenon tanks would ever make the nuclear engines obsolete.

Edited September 29, 2014 by Monthar

[Jouni]

I'm talking about proven designs that have completed nontrivial missions, not some hypothetical ships. This ship completed my first successful Moho landing:

12 ion engines, 60 xenon tanks, almost 40 tonnes, and almost 4600 m/s of delta-v in the mothership. The mass of the drive unit is 13.9 tonnes, including 1.6 tonnes of batteries. A single nuclear engine would have given 2.5x the TWR and 50% of the delta-v for the same mass. Doubling the number of xenon tanks to 120 would have increased the delta-v to 8100 m/s without affecting the TWR noticeably, while a nuclear engine would have produced 3500 m/s for the same mass.

That 8100 m/s is more than enough to compensate for the low TWR, especially considering that the real delta-v is much higher, after the lander has burned its fuel. The high part count of ion-powered ships is pretty much the only reason I'm still using nuclear engines in transfer stages.