The problem with the atomic engine now is bulk

[RocketBlam]

The atomic engines can be more efficient than regular engines... but usually only if you carry a ton of liquid fuel, and leave the oxidizer behind. This should be fine - it should balance out, and become a net positive over regular engines, and it does, when you include a LOT of tanks.

If you just use the regular, liquid fuel tanks (like are used on airplanes), you have to include a bunch of them. And though they are lighter in weight, this is counterbalanced by the huge bulk of all those tanks in the numbers you need.

So you might choose to use the regular fuel tanks, and just take out the oxidizer before you launch, but that's a problem too. Now you have huge tanks that are half empty, and will always be half empty.

One thing we need, I think, is some 2.5m tanks that are dedicated to liquid fuel only. Then we can use the whole tank volume for LF instead of launching a huge, half-empty tank. I know we have the large tanks for spaceplanes, but they can be troublesome to use in vertical, VAB rockets (having to include adapters, things don't attach in the same way, etc.)

[Sharpy]

The MK3 long liquid fuel fuselage holds only 1/3 less liquid fuel than the largest Kerbodyne fuel tank, and one such tank + LV-N gives you some 10,000 m/s dV, more than any other engine-tank combination by far (maybe save for Ion).

If you're building a spaceplane, most of your parts will be fuel tanks anyway, and you'll need liquid fuel for jet engines.

Seriously, what and where do you want to fly if - say - three such tanks (not an overkill) are not enough for you?

[Megadeath]

While the mk3 parts can certainly hold a decent amount of fuel, that doesn't really give the whole picture.

As the OP said, there's other constraints weighing against them. Especially in the VAB. To the original reasons, I'd add that I believe they have worse wet/dry mass ratio? Not sure and can't check right now.

For something like a modular interplanetary engines, among other things, it seems like a dedicated, liquid fuel tank for rockets specifically is justified.

[Feradose]

I think it simulates hydrogen fuel density really good, and should stay.. the only reason I dont use plane tanks on rockets for nukes.

edit- maybe they even should add hydrogen as a resource and add a tweakable on tanks to make them hydrogen mode.

[Red Iron Crown]

You don't need a huge amount of fuel to make the LV-N a good choice. Breakeven for a nuke over a chemical engine occurs at around 2.5t of fuel per engine, the best chemical engine would require >5t of fuel for the same delta-V. A single Mk2 LF fuselage per LV-N makes for an efficient combination. Take this tug (pic) with 4 LV-Ns, it fits inside a 3.75m fairing (and a 2-LV-N version will fit in a Mk3 cargo bay) and it can deliver 2700m/s for an orange tank sized payload. It gets even better if the tug is reused or combined with ISRU.

Definitely agree we could use a 2.5m LF-only tank, though.

[JimmyAgent007]

No new tanks unless its a size we dont have. What we do have now should be adjustable so we can tweak what fuels we have in it. An old suggestion I know but really, it makes more sense and less clutter in the menus.

[georgTF]

There's lots of issues with the LV-Ns. Same as other engines. Isp is certainly important and the nuke is king in Isp, but it's also heavy, large, tends to overheat small/sensitive parts, uses LF only which forces a slightly different fuel tank solution, and above all else it has crappy thrust for the bulk.

Is it allways the best engine for the job? No. Not unless your craft is an interplanetary SSTO or system tug/fuel tanker. It is often the most efficient choice, but not allways the most practical one. Given how good it already is when used in it's ideal conditions, why should it be improved further? It would make other engines useless.

[edit]

Atomic motors should really use a separate type of fuel, but Squad must be loathe to include yet another one. It's also neglected that when using garbage can or orange tanks, the craft benefits from better heat management in addition to carrying a bit of deadweight. It evens out.

Edited June 16, 2015 by georgTF

[Orbital Vagabond]

Scott Manley also weighed in on this about a month ago:

To sum up: Liquid hydrogen is the fuel that makes sense for nukes, and LH2 is very bulky. If we included any kind of accurate LH2 fuel, then it's tankage would be even less size and mass efficient than using the half empty LFO tanks!

- - - Updated - - -

What we do have now should be adjustable so we can tweak what fuels we have in it. An old suggestion I know but really, it makes more sense and less clutter in the menus.

On one level, I agree with this so hard it's not even funny. But on another level, I'm really conflicted about it.

The devs have stated that any kind of procedural part (beyond fairings, because...?) isn't going to be considered because they prefer the "lego" asthetic and building challenge: You have a variety of pre-fab parts, instead of the perfect part for every possible situation.

However, it's frustrating when the devs include new mechanics (e.g. LF-only nukes), then don't include the parts that feel like they support the new mechanics. See also "Where my radiators at, Squad?, Vol. XXVIII"

And I kind of hate myself for saying this, but I think sticking with the "lego" aesthetic is better option in this case. However, I would be very happy if we got a few configurations (like, 4 or fewer) for each tank size, e.g. the FLT 200 could carry LFO 9:11 (for pure LFO engines), LFO 12:4 (for dual-cycle engines), pure LF, or pure OX. The configuration could be selected in the tweakables menu, and one-fuel tanks could hold slightly more volume than fuel tanks that contained multiple fuels. I think it would be a good compromise between the two stances.

PS we still need radiators.

[Red Iron Crown]

Tweakable fuel types could also permit the elimination of the duplicate spaceplane parts and save a bit of RAM.

[regex]

Procedural Tanks needs to be stock.

[boxman]

It is really sill we canot just fill them up with whatever we want using tweakables..

I wish they did not start adding such features only to implement them just partly..

Was also hidden tweakable to make parts into rotor/ball bearings as well.. They said it was disabled currently by default because of a bug making it crash when doing time warp and that it would most likely be fixed and enabled in the next versions.

Now probably like close to a year later there has been nothing.. I bet the original developer is no longer even at squad, since they love to hire modders just to fire and replace them a month or two later.

Squad has done alot of great things with this game, but their management seems really bad...

[MLWostal]

If you want larger LF tanks then make them. Just find the tank size you want, copy (and rename) the folder in the gamedata\squad\parts folder, edit the copied .cfg file and change the fuel (changing the in game name as well).

This way, those who are purist or have tons and tons of items already in their parts folders, won't get all upset because more parts are showing up in their already overloaded listings and you have the part you want.

The new parts also have their textures as .dds so changing their colors to indicate LF only is easy.

No modding of the actual .mu, no having to learn 3d design to create new, just a few very simple changes and your version of KSP is now tailored to your own gameplay.

And if you're a 'It must be REAL!' type player, what's it matter to you is another uses something you don't agree with? With all the mods out there, why not allow others to enjoy the game as a game and not real life. Besides, last I looked, the only green people I see are the one that eat my cooking, and they are thankfully very few in numbers.

For those that want to share their .craft files, a pic is all I need to recreate most (not all as they do get complicated) of them. Never needed to download a .craft file anyway as it is much more fun to try and recreate the ship myself so I learn from my own mistakes of which, I assure you, are many.

So, shutting up now and I hope I offended no one.

[clivman]

Procedural Tanks needs to be stock.

Procedural parts is great for any realism modpack- but it really makes KSP feel like a different game.

I just don't think it would be good for stock.

[xtoro]

If you're not against part packs, try Fuel Tanks Plus. Great for more options, and LF only tanks.

[regex]

Procedural parts is great for any realism modpack- but it really makes KSP feel like a different game.

Yeah, it makes KSP feel like a much better game.

[Tankman101]

Yeah, it makes KSP feel like a much better game.

In your opinion*

Frankly Proc Parts makes the game feel too sterile (I used them).

[regex]

In your opinion*

E: Yes, I know, I thought that was implicit in this matter of taste. Edited June 16, 2015 by regex

[worir4]

E: Yes, I know, I thought that was implicit in this matter of taste.

Instead of procedural tanks, i would be perfectly happy with tweakable tanks that let you put what type of fuel you want in a tank.

[regex]

Instead of procedural tanks, i would be perfectly happy with tweakable tanks that let you put what type of fuel you want in a tank.

Anything is better than this silly LEGO crap we have now (IN MY OPINION).

[Red Iron Crown]

I'm odd about that, I prefer Lego-style for the stock game but go all procedural for RSS/RO.

[Mat2ch]

I have my Space Tug floating around Duna right now. Uses four LV-Ns. It takes some time to get somewhere, but it's very efficient. Not bulk, I'd say.

[Laie]

Procedural Tanks needs to be stock.

While I see the wisdom behind that suggestion (3 diameters x 5 heights really don't have to be represented by 15 individual parts), I respectfully disagree.

I've recently discovered a great desire to make tanks of the oddest shapes in order to fill up the free space within a fairing. Which isn't totally unlike how it happens in reality, methinks. But the ability (and necessity) to build vessels in this fashion should remain in Realism Overhaul. For stock KSP, I think it's better to have distinct and discrete sizes. That's what makes it a virtual erector kit.

EDIT: ninja'd five times over. I really should read the whole thread before I reply.

Edited June 16, 2015 by Laie

[Archgeek]

A single Mk2 LF fuselage per LV-N makes for an efficient combination. Take this tug (pic) with 4 LV-Ns, it fits inside a 3.75m fairing (and a 2-LV-N version will fit in a Mk3 cargo bay) and it can deliver 2700m/s for an orange tank sized payload. It gets even better if the tug is reused or combined with ISRU

Wow, that looks a lot more effective than my crazy Von Braun tug. Mine's got a lot more fuel and half the thrust, making for a pathetic TWR. It can get a 101 tonnes on a kerbin escape and come back, though.

[Sharpy]

Why the heck procedural?

Both LF and oxidizer sliders should go up to full tank capacity, only limited in software so that their sum doesn't go over the tank's capacity (say, the fuel bar is reflected in the right side of oxidizer bar, through a different color.

[annallia]

Instead of procedural tanks, i would be perfectly happy with tweakable tanks that let you put what type of fuel you want in a tank.

This.

I played around with procedural tanks a few versions back, honestly I didn't care for it. They were nice to limit part count (a little) but I didn't care for the looks or just the mechanics or what have you. Being able to take all the oxidizer out of a tank and make it a pure LF tank(to the volume it should be) would be exactly what I was expecting when tweakables was announced, and what I am still hoping for.