[20/11/2014][0.25] FTmN Atomic Rockets

[pina_coladas]

I love the methane idea, but lets not get too crazy here. MFS (real fuels version) considers LiquidFuel to be kerosine, KSP Interstellar considers LiquidFuel to be Liquid Hydrogen, and now another mod is going to assume it's methane? Things are getting out of hand with LiquidFuel!

[NathanKell]

pina_coladas: Nope, RF considers Kerosene to be Kerosene. I got out of the stock resource business in v4 (all except SolidFuel...I probably should just bite the bullet and add PBAN and HTPB.)

kommitz: I too support Methane (it's probably the sanest fuel for NTR, and Bob Braeunig calculated you get higher stage deltaV with it anyway, usually, given LH2's low density). And RF will obviously @name = LqdMethane your configs.

[Shad0wCatcher]

Only have one reservation about this; (thoroughly love the nukes btw, and kickass job on the modeling and texturing; it's absolutely sublime watching them burn) the little 12 kN rocket seems to have an extraordinarily low melting point at 1000 degrees centigrade. Consider that copper melts at 1083 degrees centigrade and most DRE reentries at interstellar speeds (3.3k+ m/s) put temps over 1200 you will always lose the little buggers. Is that temperature intentional?

[Kommitz]

Is that temperature intentional?

Err, probably not. Thanks for pointing it out, the temperature thresholds just have so little impact on the stock game that I tend to overlook them. I'll make them all a bit more consistent next update.

I love the methane idea, but lets not get too crazy here. MFS (real fuels version) considers LiquidFuel to be kerosine, KSP Interstellar considers LiquidFuel to be Liquid Hydrogen, and now another mod is going to assume it's methane? Things are getting out of hand with LiquidFuel!

Ahhh it's not actually going to be *methane*, I'm just using it as an archetype that makes a bit (definitely only a bit, it's still unrealistic) more sense than the current stock NTR stats. If I wasn't too bothered about mod reliance I'd just go ahead and fuel them with Kethane (I suppose that could be a useful alt config).

[Lurven]

Err, probably not. Thanks for pointing it out, the temperature thresholds just have so little impact on the stock game that I tend to overlook them. I'll make them all a bit more consistent next update.

Ahhh it's not actually going to be *methane*, I'm just using it as an archetype that makes a bit (definitely only a bit, it's still unrealistic) more sense than the current stock NTR stats. If I wasn't too bothered about mod reliance I'd just go ahead and fuel them with Kethane (I suppose that could be a useful alt config).

Kethane fueled engines? Sounds awesome

[Fried_Soup]

Hey I have a problem, It seems like this mod is not compatible with Engineer. Is it just me or what?

[Surefoot]

The big engine (the 280) overheats much more quickly than the NERVA from Novapunch, while in space. These engines have very close specs (the NERVA is a tad more power hungry), on my test ship i never had a NERVA overheat on me in vacuum, the 280 overheated pretty quickly. What is the reasoning ?

[LameLefty]

I'm thinking of changing the engines to work more like methane nuclear engines, which would have greater thrust than (typical) hydrogen nuclear engines but a lower Isp. Basically change the engines to just use LiquidFuel, increase the thrust by maybe 1.5 or so and drop the Isp down to 600. Doing this would necessitate using Modular Fuel Tanks plugin to keep things from getting confusing with the stock fuel tanks, but I can always leave the current configs available as an alternative.

Thanks for the new update Kommitz. I adore these engines and use them in almost everything; to me they offer a much better combination of stats than the singular stock LV-N offering. Having never used any of the alternate resource type mods other than Kethane in the past, I'm not really sure why your proposed change would require Modular Fuel Tanks. Can you (or anyone else) explain the implications of that? Even when I've used Kethane I just convert it to fuel/oxidizer or mono prop as needed, never having bothered with Kethane fueled engines.

[Kommitz]

The big engine (the 280) overheats much more quickly than the NERVA from Novapunch, while in space. These engines have very close specs (the NERVA is a tad more power hungry), on my test ship i never had a NERVA overheat on me in vacuum, the 280 overheated pretty quickly. What is the reasoning ?

I've never had the engines overheat on me, even in clusters. It's probably the specific fueltank you've it/them mounted on that's causing it, or the size of the cluster. Could do with more information.

Can you (or anyone else) explain the implications of that?

I was just thinking it would be handy to use modular fueltanks so you could devote whole, stock tanks to just liquidfuel rather than either using tweakables to half empty them or adding a load of not-especially-useful liquidfuel only tanks.

Edited January 5, 2014 by Kommitz

[Guest]

The big engine (the 280) overheats much more quickly than the NERVA from Novapunch, while in space. These engines have very close specs (the NERVA is a tad more power hungry), on my test ship i never had a NERVA overheat on me in vacuum, the 280 overheated pretty quickly. What is the reasoning ?

Treat it like a Mainsail from pre-0.23, put a short tank between it and the main tank. I've had them explode when attached to the half-orange tank, but even a quarter-orange tank will keep it in check.

[kiwiak]

Hey I have a problem, It seems like this mod is not compatible with Engineer. Is it just me or what?

It seems that i have this problem too.

[Surefoot]

I've never had the engines overheat on me, even in clusters. It's probably the specific fueltank you've it/them mounted on that's causing it, or the size of the cluster. Could do with more information.

I see. Each engine is attached individually to a 2.5m stretchy tank (which is quite big in my test here). 8 of them, in radial symmetry, around a 5m diameter tank, total ship is around 600t.

I'll see if replacing the stretchy tanks with stock-like (Novapunch or KW) changes anything. (edit) i mounted them on KW 2.5m tanks, no change, still overheating very quickly at full thrust, even on a much lighter ship.

Edited January 5, 2014 by Surefoot

[Apfelmus]

Hey I have a problem, It seems like this mod is not compatible with Engineer. Is it just me or what?

It seems that i have this problem too.

Same here, too. Mechjeb also doesnt work :/

I've tried to compare the FTmN engine's .cfg file with a regular stock engine, but nothing seems to be missing.. did you have any success in figureing out what the problem could be??

[Surefoot]

I am using these engines with Mechjeb and have no issue there...

[LameLefty]

I am using these engines with Mechjeb and have no issue there...

Ditto. And I have MJ set to "Prevent Overheats" while it runs my long interplanetary transfer burns. MUCH easier than jockeying the throttle manually for 5 - 15 minutes.

[SHaFT7]

The big engine (the 280) overheats much more quickly than the NERVA from Novapunch, while in space. These engines have very close specs (the NERVA is a tad more power hungry), on my test ship i never had a NERVA overheat on me in vacuum, the 280 overheated pretty quickly. What is the reasoning ?

just edit the max temp in the cfg file to match the stock NERVA. problem solved.

[Mystique]

Is everybody not including electric charge generation in their engine on a purpose? Well, at least double atomic engine could have that feature, I guess.

[Gaius]

Not everybody; LLL's atomic engines generate power even when not firing.

[TomatoSoup]

I see. Each engine is attached individually to a 2.5m stretchy tank (which is quite big in my test here). 8 of them, in radial symmetry, around a 5m diameter tank, total ship is around 600t.

I'll see if replacing the stretchy tanks with stock-like (Novapunch or KW) changes anything. (edit) i mounted them on KW 2.5m tanks, no change, still overheating very quickly at full thrust, even on a much lighter ship.

Pardon me, my good sir, but where in the name of all that is holy are you going with that?

[Surefoot]

That's not so much, i've done a 1700t ship too These are cargoes, the payload is extra heavy. So the final deltaV with the payload attached is not so huge (in the high 4000's) so i can go to Jool and come back without refuelling (since they are fuel cargoes..). One of these engine blocks is used for my Grand Tour too, in this case i have just over 6500m/s in dV to be able to go everywhere with a safety margin since i only refuel with Kethane (so it's not always a net profit).

Edited January 6, 2014 by Surefoot

[Mystique]

Just installed deadly reentry and biggest of those engines blows up in ~20 sec of full-power burn. Before using deadly reentry I made similiar burn, temperature was high, but definitely not overheating. Can it be some incompatibility?

Burn is done in vacuum 20000 km above Jool. Tried limiting throttle for this engine for 60% - same result. Log says that in exploded due to reentry

Edited January 6, 2014 by Mystique

[Surefoot]

Yeah i edited the cfg file to match the stock NERVA configuration and indeed its max temp is much lower than the stock one for some reason (and heat production is higher). That would explain the quick blow-up with DRE.

[Mystique]

Well, I hope it'll be taken into account in next release

Update: err, in both stock atomic engine and ftmn280.cfg I see "maxTemp = 4000" (even though heat production is a bit different, but engine is also quite large, so it's logical). But in FTmN there is also "breakingForce = 200 breakingTorque = 200", maybe there is the catch with DER?

Edited January 7, 2014 by Mystique

[Ranmaru]

maybe there is the catch with DER?

Assuming you meant Deadly Re-entry, yes there is. Part of the code or DRE caps the maximum temperature to 1600. Seems to halve it in the case of the 280 model though as I got that up to 1800 degrees without blowing up. Took me a while to figure out why I couldn't have the large engines at more than ~45% thrust ^^;

Doesn't compensate for engines at all it seems.

Anyhow, if anyone is using deadly re-entry, you need to go to your config file and adjust the Heat production to compensate; 248 for the large engines, and possibly 280 for the fmt40 (didn't seem to be behaving that abnormally to me). The tiny engine is perfectly fine though.

Mathematically there should be no difference, but it may need a bit of fine tuning

[Mystique]

Yep, that seems to be the problems. Hope mods will be made compatible soon, for now I'll also amend configs - don't really like to take huge engines and run them and 50% max in deep space