An extremely stupid idea

[Skye]

Just before I say anything: this is in no way whatsoever a serious proposal, and it’s purely a silly investigation 

My friend came up with a highly silly idea: what is the most awful rocket engine you could make - in terms of both handling AND performance.

I responded with a few traditionally awful propellants, as well as some less awful ones, but still icky to handle (it ended up as an quindecapropellant engine)

F2, O3, N2O4, ClF3 & 5, UDMH, H2, Li, Hg, Al, N2, B2H6, B5H9, B10H14, and - god forbid - Og. (Oganesson may be combustible, not yet proven, but you can swap this out with any extremely heavy combustible element, really)

The reason Og is there is because, not only is it radioactive, to decrease handleability, but it is also extremely heavy, which means minimal Isp.

The reason nitrogen in there is because it takes a ton of energy to break the bonds.

Most of these are fairly obvious - they’re either extremely reactive, toxic, unstable, flammable, radioactive, etc.

Hydrogen is there just because it’s flammable & super cold, but it’s not too bad aside from that. Either way, as Tesco says, “every little helps”

Literally no limit here - feel free to put any and all abominable propellant combinations!

Any you may ask “why?!” And I wouldn’t blame you, but I ask “why not?”

[Apollo22]

Hard to beat fluorine, for a start. Also the boron fuels.

[Skye]

Oh my god, how could I forget the boranes!

I’ll fix it

[laszlo]

The old Project Orion bomb chuckers. Start with a take-off that makes Musk's concrete tornado look positively amateurish, leave a trail of deadly fallout to be blown all over the planet behind you, flash and radiation burns and permanent blindness for everyone that you pass over, destructive over-pressures until you leave the atmosphere and a continuous sequence of EMPs all the way to orbit, just to to destroy the planetary tech infrastructure. Destroy every satellite in orbit, blind every orbiting observatory and kill every human in space with radiation or electronics failure or both. And that's a nominal launch.

All the fun of a nuclear exchange and a really big rocket. Somewhere there's a billionaire for that.

[Skye]

Yup, I think that mostly takes the cake. Is there anything potentially more hazardous than that?

Also, look at the stats of the biggest one, you could easily end the world with one nuclear pogo stick hopping from country to country.

I was tempted to make a thousand-yard-stare joke, but couldn’t be bothered, so [insert funny 1000-yd-stare joke here]

[edzieba]

Anything below the Nuclear Salt-Water Rocket is not worth considering on the "I don't want to be in the same solar system as that thing" scale.

[Bob Shaw]

This thread is why I come to NSF! Please keep up the bad work.

[Skye]

We absolutely will!

[Skye]

Anything below the Nuclear Salt-Water Rocket is not worth considering on the "I don't want to be in the same solar system as that thing" scale.

What about some hideous combo of Orion and NSWRs?

[Vultur]

I believe there was at one time a proposal called Helios, which was like Orion except that the nuclear explosions were meant to be contained in a "combustion chamber" - somehow...

EDIT:
The Wikipedia article actually links to an old paper
on the subject https://www.osti.gov/servlets/purl/6761138-yMEAhk/

"No fundamental fault in the concept has been found" ... "there is no reason to doubt such efforts would result in a working engine" (!!!)

Wow, they were very optimistic back then!

[Twark_Main]

Og. (Oganesson may be combustible, not yet proven, but you can swap this out with any extremely heavy combustible element, really)

The reason Og is there is because, not only is it radioactive, to decrease handleability, but it is also extremely heavy, which means minimal Isp.

The problem is you make it too radioactive and it starts contributing energy to the exhaust and starts improving efficiency, which is undesirable.

It also has worse than just "handling problems," it vanishes in milliseconds.  If we're gonna go down that route we might as well select neutronium as our propellant. 


No, you want that sweet spot of high atomic number, high radiation, but also long lifespan. In that spirit I recommend Caesium-137 + liquid Fluorine as the worst propellant combination imaginable.   

https://en.wikipedia.org/wiki/Caesium-137

Fluorine is an objectively worse oxidizer choice, but I have to admit Caesiolox (and Neutroniolox) do have a nice ring to them. I guess we have to settle for Caesioflox ("Fluorine liquid oxidizer")

[Vultur]

  If we're gonna go down that route we might as well select neutronium as our propellant. 

Now that sounds like a winner!

[Skye]

Og. (Oganesson may be combustible, not yet proven, but you can swap this out with any extremely heavy combustible element, really)

The reason Og is there is because, not only is it radioactive, to decrease handleability, but it is also extremely heavy, which means minimal Isp.

The problem is you make it too radioactive and it starts contributing energy to the exhaust and starts improving efficiency, which is undesirable.

It also has worse than just "handling problems," it vanishes in milliseconds.  If we're gonna go down that route we might as well select neutronium as our propellant. 


No, you want that sweet spot of high atomic number, high radiation, but also long lifespan. In that spirit I recommend Caesium-137 + liquid Fluorine as the worst propellant combination imaginable.   

https://en.wikipedia.org/wiki/Caesium-137

Fluorine is an objectively worse oxidizer choice, but I have to admit Caesiolox (and Neutroniolox) do have a nice ring to them. I guess we have to settle for Caesioflox ("Fluorine liquid oxidizer")

Dear. God.

[Joris]

As far as actually flown awful rockets go: About 39 years ago, RBMK reactor 4 at Chernobyl accidentally turned into a 30GWth¹ NTR that hit an apogee of several meters.

The mass of the upper biological shield with attached parts that was thrown upwards was around 2000t.²

If we assume the force was about 1.5 times the weight, so in a second it would go up a few meters, then it gives us a specific impulse of about 200s during that short flight.





1. https://www.oecd-nea.org/upload/docs/application/pdf/2020-07/neacrp-a-1987-0825.pdf
2. https://www.rri.kyoto-u.ac.jp/NSRG/reports/kr79/kr79pdf/Malko1.pdf

[Skye]

Oh, yes, I recently watched a short documentary on the disaster in physics class (we’re doing nuclear fission & fusion), where they briefly mentioned that, though whether it’s a rocket or not is debatable