Suborbital Reusable NTTR Boosters

[Spacescifi]

 

So I thought of a IRL way to combine the benefits of rocket staging with reusuable NUCLEAR airbreathing rockets.

I know it is not politically practical, but physically I think it might be.

Concept: Take several nuclear thermal turbojet airbreathing rockets with the bare essentials. It's just a rocket body with an engine, a reactor, and whatever radiation shielding that is needed. No cargo at all.

These are booster rockets.

 

I know NTR originally had a poor TWR (thrust to weight ratio), but these bare minimum air breathing NTTR should help with that perhaps?

Can a NTTR reusuable airbreathing booster compete with a non-reusuable SRB or a reusuable chemical booster?

 

Could rockets reap any benefits from a normal staged launch, a simultaneous NTTR airbreathing booster launch, and then dropping the SRB'S and having a bunch of NTTR boosters connect to the hull and boost them into suborbital, where the spacecraft rocket takes over and drops the NTTR which fly around and land on Earth?

Edited March 24, 2020 by Spacescifi

[Ruedii]

Well, first of all, air-breathing nuclear-turbojets are very impractical and ineffective because air isn't a particularly good conductor of heat.  This means the heat exchanger has to have increased surface area, and thus be heavier.

More effective variants use a wet system where a coolant heated by the heat exchanger is injected into the airstream.  Typical coolants would be methanol, liquid CO2, Liquid Helium or Liquid Hydrogen.  The combustion of the coolant is minimal and not a real source of expansion compared to the raw heating power of this setup.

Even water can be used in this manner, but it isn't the most effective option.  It's thermal properties and boiling properties pale in comparison to methanol, which is the least effective coolant I mentioned.  As of where water is used in the design, it is usually used as a stage 1 coolant to move heat from the reactor core to the heat exchanger, which would be water or heavy water in a traditional design, although newer reactor designs small enough for this purpose move to molten salt or other materials less prone to boil-off.  

There were experiments with this sort of thing in the 60s and 70s, but none of them were deemed practical, and most of them exceeded the radiation leakage level for regular usage.

Honestly, if air-breathing nuclear-turbojets were determined a viable option, there would be no stopping the US Military from using them for Operation Chrome Dome in the early 70s.  No amount of political pressure would outweigh the option to have bomber that only has to land to take on food and water supplies for it's crew.

 

[Scotius]

Russians tried:

https://en.wikipedia.org/wiki/9M730_Burevestnik

It didn't work too well.

https://en.wikipedia.org/wiki/Nyonoksa_radiation_accident

 

[DDE]

19 minutes ago, Scotius said:

It didn't work too well.

https://en.wikipedia.org/wiki/Nyonoksa_radiation_accident

An equipment recovery incident does not impugn on the design principle. And IIRC multiple housing blocks for Rosatom employees have been built at the launch site at Kapustin Yar, suggesting a potential shift to overland launches and not just nav tests.

Edited March 24, 2020 by DDE

[sevenperforce]

If nuclear-thermal air turborocket engines were good as boosters, they would be good as main-stage engines.