The infrared radiation coming from the five F-1 engines of the Saturn V flash ignited the grass around the launch pad during most lift-offs. And that was just a measly 263 s of Isp. A fusion drive would really be slice of hell. An ion drive is ludicrously hot as well, but the actual power flowing into it is low, and therefore so is the heat coming out.
If the engines are canted outwards, then the reduction in efficiency has to be taken into account when deciding between a puller/pusher configuration - I'd imagine the net delta-v would go down with the cosine of the angle the engines are canted out at. At some point it would be probably better to invest some mass into a truss and parallel engines (α=0°) instead of losing a third of your delta-v to angling the drive (α=45°) in an attempt to avoid the plume.
If the engines are canted outwards, then the reduction in efficiency has to be taken into account when deciding between a puller/pusher configuration - I'd imagine the net delta-v would go down with the cosine of the angle the engines are canted out at. At some point it would be probably better to invest some mass into a truss and parallel engines (α=0°) instead of losing a third of your delta-v to angling the drive (α=45°) in an attempt to avoid the plume.
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