Long duration nuclear airplanes - sswelm/KSPInterstellar GitHub Wiki

The first reactor tech you'll encounter in KSP Interstellar gives you nuclear fission reactors. Fission reactors are powered by Uranium Tetraflouride or Thorium Tetraflouride. Uranium and Thorium are quite large by atomic standards; so large in fact that whenever they absorb a neutron they will split in two (fission), releasing a large quantity of energy. This energy is released as heat, and can be used to do work.

The simplest way to use a nuclear reactor to provide thrust is to suck in air, heat it up, and throw it out the rear of the plane. You can use ordinary air intakes for the former. KSPI provides a Thermal Turbojet to do the latter. Craft built with the Thermal Turboject will require no liquid fuel, and will therefore function for as long as your reactor lasts, potentially for decades. Note that the thermal turbojet must be attached directly to the reactor; moving heat around is complicated engineering-wise, and would introduce efficiency losses, so it's not currently supported. Also, multiple nozzles per reactor are unnecessary. The heat would be split equally between them, giving you the same thrust as a single turbojet but with added weight.

Fission reactors are, however, quite heavy. The nuclear fuels are heavy, the radiation shielding they require is heavy, etc.

Surprisingly, they also do not produce huge amounts of thrust. What thrust they do produce is quite efficient, and since you require no liquid fuel your craft will be quite compact.

To supply the electrical needs of your craft you can attach an Electrical Generator to the reactor. The generator will consume some of the heat from the reactor, using it to produce electricity. It will scale it's heat consumption continuously to match the electrical requirements of your craft, leaving the rest for the turbojet.

First steps

A good way to design your first nuclear-powered airplane is to load up the stock Aeris 3A and replace the jet engine and liquid fuel with a nuclear reactor and thermal turbojet.

First, take the wings off and put them aside. Then, remove the fuel tanks and engine and discard them. Add a 1.25 meter KIWI reactor, and the thermal turbojet in their place. Put the wings back in place, taking care to that the center of lift is slightly behind the center of mass. Finally, add two radiators to dissipate waste heat.

 

(add more detailed engineering guidelines)