More situational engines in ksp 2 : NHSER

[Xelo]

Would it be cool to have engines that seem like ISP downgrades, but are more economical to maintain? Like playing off ISRU perhaps we could have an engine (concept below) that superheats harvested water ice directly with a nuclear reactor and avoids the expensive equipment required to handle, contain and and convert water into liquid oxygen/ liquid hydrogen needed in more conventional chemical engines (the ejected water with this engine might also be good for carrying waste heat away and reducing the need for radiators). This could provide like a cheap supply of water for orbital colonies around bodies with large deposits of water ice. 

^{I wanted to name it NISER, but couldnt think of a word for I, so Nuclear Heated Steam Emitting Rocket it is.}


A smaller variant!

Edited May 21, 2022 by Xelo

[Catto]

2 hours ago, Xelo said:

Would it be cool to have engines that seem like ISP downgrades, but are more economical to maintain? Like playing off ISRU perhaps we could have an engine (concept below) that superheats harvested water ice directly with a nuclear reactor and avoids the expensive equipment required to handle, contain and and convert water into liquid oxygen/ liquid hydrogen needed in more conventional chemical engines (the ejected water with this engine might also be good for carrying waste heat away and reducing the need for radiators). This could provide like a cheap supply of water for orbital colonies around bodies with large deposits of water ice. 

^{I wanted to name it NISER, but couldnt think of a word for I, so Nuclear Heated Steam Emitting Rocket it is.}

KSP2'S gotta have it. I'm guessing it's 2.5m/3.75m sized?

[Rutabaga22]

Love this! maybe give a little boost to interplanetary freighters

 

[Xelo]

27 minutes ago, Catto said:

KSP2'S gotta have it. I'm guessing it's 2.5m/3.75m sized?

Yus, id imagine there to be smaller 1.25m variant too!. Ill probably draw that and add it to the original post.

[Ryaja]

That sounds awesome

[Davi SDF]

Yeah, cheap to use engines would be great for launch, specially to launch some fuel for the high ISP engines!

Also: Really REALLY GREAT drawing!

Edited May 20, 2022 by Davi SDF

[Maria Sirona]

Maybe it could be NISER with I meaning ignition?

[jimmymcgoochie]

An NTR using water as its propellant would get worse ISP than a hydrolox chemical rocket (at best, ~410s ISP versus >450s that hydrolox engines can already achieve).  Water also has the unfortunate tendency to dissociate into hydrogen and oxygen at very high temperatures, such as those found inside a nuclear reactor for an NTR; you really don't want hot oxygen inside a nuclear reactor, and you especially don't want hydrogen gas in there too!

You'd still be better off using that nuclear reactor to power an electrolysis cell, then liquefy the hydrogen and oxygen produced, with the waste heat from the reactor used to melt the ice before it gets electrolysed. You could then use the liquid hydrogen in an NTR and enjoy the benefits of neutron moderation and cryogenic cooling that come with it- more hydrogen directly increases the fission rate, but also cools the reactor more- or with most of the oxygen in a hydrolox rocket, with the excess oxygen used to keep the crew alive. Most hydrolox rockets burn fuel-rich to help with cooling, increase ISP by lowering the average molecular mass of the exhaust gas and also because hot oxygen is really reactive and is just as bad for the inside of a rocket engine as it is for the inside of a nuclear reactor.

Edited May 21, 2022 by jimmymcgoochie

[Xelo]

Yeh, my original post states the ISP is worse, but it could potentially have better upfront and running cost. 
The thermal splitting of water also doesnt really happen at the temperatures the engine is running at (1100K), since once thermal splitting happens to a signficant degree youd need to starting worrying about how you are going to contain 2200C steam without melting the engine itself. Electrolysis would be the fuel-efficient option, but this is not what the engine is about, since the fuel of water ice is implied to be cheap and readily available, and the only problem is bringing it to orbit in large quantities at a reasonable cost. 
This engine was inspired by this document, which concludes that the mass and complexity of the electrolyser would not be worth it if the aforementioned condition of water fuel being cheap was true and the deltaV was small (< 6km/s).
http://www.neofuel.com/staiff1999/index.html

And about " especially not wanting hydrogen gas" in a reactor, isnt that just how hydrogen nuclear thermal rockets operate?

Edited May 21, 2022 by Xelo
forgor

[Bej Kerman]

27 minutes ago, Xelo said:

running cost

Who said KSP 2 would have "running costs"?

[Xelo]

10 minutes ago, Bej Kerman said:

Who said KSP 2 would have "running costs"?

Who said it wouldnt :p (whats preventing me from spamming a million automated deliveries to my colonies in any case? Is the rocket just free?), besides most of the cost savings would be in the upfront portion anyway owing to its simpler design.

[Bej Kerman]

1 hour ago, Xelo said:

Who said it wouldnt :p

"Who said it wouldn't" isn't a valid argument, is it now? You can't just make anything up and say "no-one has debunked it yet!". Why don't you actually show us where you found that KSP 2 parts would have running costs?

[Xelo]

1 hour ago, Bej Kerman said:

"Who said it wouldn't" isn't a valid argument, is it now? You can't just make anything up and say "no-one has debunked it yet!". Why don't you actually show us where you found that KSP 2 parts would have running costs?

Sure! have it your way. Running costs, as ambiguous as that term is, does not exist in any capacity in KSP2 and cannot be used or even implied in a suggestions forum topic because suggesting something not confirmed in the game would be the work of the devil, is a logical fallacy and therefore is disallowed.

Edited May 21, 2022 by Xelo
clarification

[intelliCom]

On 5/20/2022 at 8:55 AM, Xelo said:

I wanted to name it NISER, but couldnt think of a word for I, so Nuclear Heated Steam Emitting Rocket it is.

Nuclear
Irradiated?
Steam
Emitting
Rocket

[Bej Kerman]

17 hours ago, Xelo said:

Running costs, as ambiguous as that term is, does not exist in any capacity in KSP2

Look, honesty. Thank you and goodbye.

[CerealBug]

Neat concept! I like the idea of having a low-performance but low-complexity alternative to some of the more exotic propulsion concepts shown so far. I could see NHSER or something like it being really useful in the early stages of a colony, as it gives some (limited) launch capability without having to deal with the cost/complexity of building or flying in a full fuel production setup. 

On 5/21/2022 at 2:54 PM, Bej Kerman said:

Who said KSP 2 would have "running costs"?

I think OP's  use of "running costs" more generally refers to the cost and complexity of fueling the engine. For example, the NHSER concept here has a low running cost since it just needs water to be mined out of the regolith, a chemical engine would have a middling running cost due to the need to further process the raw materials into a usable state, and something like an antimatter engine would have a high running cost due to the high complexity and energy requirements of generating antimatter.

[Bej Kerman]

48 minutes ago, CerealBug said:

On 5/21/2022 at 7:54 PM, Bej Kerman said:

Who said KSP 2 would have "running costs"?

I think OP's  use of "running costs" more generally refers to the cost and complexity of fueling the engine. For example, the NHSER concept here has a low running cost since it just needs water to be mined out of the regolith, a chemical engine would have a middling running cost due to the need to further process the raw materials into a usable state, and something like an antimatter engine would have a high running cost due to the high complexity and energy requirements of generating antimatter.

I glad you could properly elaborate on what the OP didn't bother explaining. Thank you.

[Xelo]

5 hours ago, Bej Kerman said:

I glad you could properly elaborate on what the OP didn't bother explaining. Thank you.

I assumed you knew, hence why you went "Why would ksp2 have running costs???" like you understood what i meant and wanted to argue against its existence, as opposed to "What do you even mean by running costs and why would ksp 2 even have them?", which i would have obliged the explanation and clarified.
Apologies for miscommunication either way, we got off to a rocky start and Im not used to a forum environment yet.

Edited May 28, 2022 by Xelo
clarification

[Bej Kerman]

4 minutes ago, Xelo said:

I assumed you knew, hence why you went "Why would ksp2 have running costs???" like you understood what i meant and wanted to argue against its existence, as opposed to "What do you even mean by running costs and why would ksp 2 even have them?", which i would have obliged the explanation and clarified.
Apologies for miscommunication either way, we got off to a rocky start and Im not used to a forum environment yet.

Understandable, cheers