Nuclear turbojet open and closed cycle

[Space_Wyvern]

I have a proposal for a (really really)endgame engine that is a nuclear powered R.A.P.I.E.R in it`s open cycle it utilizes the nuclear reactor to heat and expand the atmosferic air to provide thrust,when clear from the atmosphere you would change to the closed cycle that uses the internal propelent like the Nerv engine.

Well:
It would be much overpowered?
Yes.
Even for a endgame engine?
I guess not,it would be the game`s last engine.
 
Why would you make such a engine?
To make more dinamic SSTOs that can make a bit longer trips not using mk3 parts.

So, what you guys think of this in the stock game?
And if there`s a mod that have a engine like that let me know please.
 

[Wjolcz]

The RAPIER is already pretty good. At least it was the last time I used it. Tbh I'd rather see a VASIMR engine than a nuclear RAPIER. It would also be much more realistic to have an electric propeller engine instead of nulcear hybrid engine for atmospheric flight.

Edited January 24, 2016 by Veeltch

[Temstar]

Dual-mode nuclear engine is a good idea, problem is it makes certain really challenging aspect of KSP (eg: Eve ascent) really easy. It needs some kind of drawback.

[Pds314]

First we should have regular nuclear turbojets and ramjets. Consider, for example, the SLAM / project Pluto / the flying crowbar involved a 600 Megawatt reactor at nearly 1300 °C being used as a 35000 lb thrust ramjet, comparable to the engine of the F-35 on full afterburner.The reactor was 1.5 meters across, so I think making a 150 kN nuclear ramjet at 1.25 meters and several tonnes is pretty reasonable.

With regards to putting it at the endgame, maybe for a nuclear aspirated rocket, but if we're going for realism here, the Convair X-6, powered by a reactor running props, flew by 1955. The Tu95LAL, a similar aircraft built by the USSR, flew in 1961. The fully functional Tory-IIc engine was tested in 1964. All of these projects were shut down due to the development of practical ICBMs. Far from being endgame tech, nuclear jet engines were around before we got to the moon. Additionally, chemical jet engines are finicky by comparison. A chemical jet engine needs to atomize a fuel stream and mix it into a fast- moving airstream in such a way that it efficiently burns inside the engine and leaves sufficient oxygen for the rest of the fuel. Combustion instability is the single most significant reason Scramjets are tricky to make.

By comparison, a nuclear turbojet is little more than a sophisticated hairdryer. Heating elements heat up whatever goes in, exhaust is used to turn a fan to suck more air in, and the cycle continues. No fuel flow, no combustion instability, and a number of mechanical parts you can count on one hand. Technically, you could literally just strap a nuclear turbojet to the outside of a plane and it would work, although in practice, you'd want to allow monitoring and control of the reactor by the pilot.

Edited January 25, 2016 by Pds314

[SSgt Baloo]

Relevant: https://en.wikipedia.org/wiki/Project_Pluto

Also relevant: https://en.wikipedia.org/wiki/Supersonic_Low_Altitude_Missile

Also, also, also relevant: http://jalopnik.com/the-flying-crowbar-the-insane-doomsday-weapon-america-1435286216

[Pds314]

1 hour ago, Temstar said:

Dual-mode nuclear engine is a good idea, problem is it makes certain really challenging aspect of KSP (eg: Eve ascent) really easy. It needs some kind of drawback.

There are drawbacks. For one thing, reactors cost a mint. For another, if they implemented radiation and radiation shielding, there'd be a need to protect the pilot, crew, and possibly payload from the reactor's deadly radiation. I'm not sure what the radiation dose would be, but I'm sure a lethal dose would accumulate pretty rapidly for someone sitting near a gigawatt reactor with little or no shielding. All this adds additional weight to the system, which means you need to bring that weight with you to begin with, and bring it home if you plan on using the rocket mode to do that.

[A35K]

If you really want them, just get the Interstellar mod, it has those and a whole bunch of awesome technologies.

[Porkjet]

Theoretically possible I guess, but if you want it's stats even remotely realistic, It'll be so heavy that it barely lifts your aircraft off the ground. If you disregard radiation shielding, it'll work better, but spray radioactive death anywhere around it, and be lethal to any pilots. I guess you're looking for a sci-fi miracle engine.

[AeroGav]

6 hours ago, Porkjet said:

Theoretically possible I guess, but if you want it's stats even remotely realistic, It'll be so heavy that it barely lifts your aircraft off the ground. If you disregard radiation shielding, it'll work better, but spray radioactive death anywhere around it, and be lethal to any pilots. I guess you're looking for a sci-fi miracle engine.

Interstellar is one option, but it's a weighty mod with some bug issues, and IMHO their dual mode nuclear engine is too powerful.   

A  better balanced dual mode engine, based on the NERV would 

a) weigh as much as a NERV plus a PANTHER,  to allow for the mass of the added turbomachinery.

b) provide slightly more thrust than a NERV in air breathing mode, but not much more.  This is tricky to get right.  2x more feels a little OP down on Kerbin, but isn't enough for Eve.

c) In air breathing mode, the velocity and air density curves should probably be similar to the Panther.   This is because the panther most closely models military jet engines that have actually been built,  WHIPLASH's ludicrous thrust gain at high mach and insane TWR do not.  The Rapier appears to be based on the proposed SABRE engine, which cools intake air with the cryogenic fuel stream.  In air breathing mode this engine has no fuel stream, so that is moot.

d) probably have slightly worse ISP in closed cycle.

 

Like the NERV,  it would only have radiation shielding at the front (a "shadow shield")  to stop the gamma rays reaching the cockpit.   Once this engine is fired up for the first time,  approaching from any direction other than in front results in you getting fried.

I really hope you guys bring this into the game as a stock part.   Would make our spaceplanes viable on more than just Kerbin and Laythe,  in fact given that bodies without atmosphere tend to have low gravity, you could use one in most of the Kerbol system.

I actually went so far as to mod my own in 1.04..