Dave C has issues with radiation, which has been identified recently in Sci. American as the principle hazard to interplanetary, space, travel.
stutefish, you're worried about atmospheric drag.
By odd choice, magentic fields can push the atmosphere out of the way before the edge of the ship arrives...oxygen is a magnetic gas and will respond to strong fields, modifying supersonic shock waves. It was tried in the sixties on some reentry vehicles to facilitate communication during Gemini/Apollo missions, but without success.
Now if a limiting strength magetic field..~10 ¹¹Gauss were involved in the propulsion effect, it'd also deflect lots of the ISM, reducing radiation exposure. In order to function effectively, a small surface area would necessarily need a reversed effect to allow a local gradient for walking around inside. That of course, if possible would enable a beamed gradient, down and out through a portal....anyone or "thing" outside the ship, would be accelerated and directed into the portal....a "tractor" beam as it were.
Now, if you're out stargazing, and a black silent disk slips over the horizon and pauses above you, be careful, if a metallic voice says..."Step into the light". Sweet dreams. Pete.

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A third rate theory forbids.
A second rate theory explains after the fact.
A first rate theory predicts.
A. Lomonosov