Electric fighters jets (sub-orbital and orbital versions for that matter) are quite possible with existing on-board nuclear power.
Really ? The last time I checked, they spewed radioactive reaction material. The shielding needed to prevent that was too heavy for aircraft. There was a project in the 50’s & 60’s that was deemed a complete failure.
Did you have a link to the successful projects ?
If it were possible, how do you explain the B2 not being built that way ? Eliminating the need for refueling and the unlimited range provided by a nuclear reactor would be a precious military advantage.