Plausible Sci-Fi FTL

[DDE]

3 hours ago, MaxwellsDemon said:

Oh, yeah.   What I meant to stress that, in Drake's RCN series, the drives are chemical/nuclear drives inside atmosphere, and then "High Drive" (matter/antimatter) in vacuum, the explanation being that there's cumulative wear to the High Drive engines from the matter/antimatter reactions, so it's best used sparingly in a more matter-rich environment like an atmosphere.   I don't know how much scientific water that holds, but it at least sounds reasonable.   But what it does mean is that ships use three different methods-- two kinds of reaction drive and the "sailing" rig-- to get around.  (The series is consciously based on a sort of sailing-ship-era pace, with the Jack Aubrey/Stephen Maturin novels of Patrick O'Brien an obvious and acknowledged influence, so the parallels to oceanic travel are deliberate.)

Hey, it's worked for David Weber!

As to "high drives", you can always replace the wear with radiation and/or toxicity. That way, you get a long list of very real thrust systems. Open-cycle liquid-core and gas-core rockets. Orion drive, depending on your safety thresholds. Salt water nuclear rocket, definitely. Antimatter drives, arguably, due to high gamma emissions. Any chemical thrusters using fluorine, beryllium and boron.

And, if you ask me, I'm just not letting FTL ships land pretty much ever. Take off, Convair Nexus-style, maybe. Encasing a large interplanetary dV and an FTL drive into an aerodynamic hull with enough TWR? Just use shuttles, unless you really need to transport a large single piece of highly sophisticated equipment; basically an An-225 Mriya, and note how they only ever made one of these.

[magnemoe]

7 hours ago, DDE said:

Hey, it's worked for David Weber!

As to "high drives", you can always replace the wear with radiation and/or toxicity. That way, you get a long list of very real thrust systems. Open-cycle liquid-core and gas-core rockets. Orion drive, depending on your safety thresholds. Salt water nuclear rocket, definitely. Antimatter drives, arguably, due to high gamma emissions. Any chemical thrusters using fluorine, beryllium and boron.

And, if you ask me, I'm just not letting FTL ships land pretty much ever. Take off, Convair Nexus-style, maybe. Encasing a large interplanetary dV and an FTL drive into an aerodynamic hull with enough TWR? Just use shuttles, unless you really need to transport a large single piece of highly sophisticated equipment; basically an An-225 Mriya, and note how they only ever made one of these.

Many drives like ion drives and probably most fusion rocket designs would not work well in the atmosphere as the atmospheric gasses will enter the reaction chamber, the other issue is radiation an polution as you say.
Also ship designs this is larger issue, an ship for deep space use has totally different design than one who is designed to land, this issue increase with travel time and size. 
Being able to land makes sense for an smaller ship, an yacht, tramp freighter or military special operations. 
For larger ships, no as the design requirements are so different. reloading is not an new thing either. Most businesses don't have their own harbor or railway track. passengers are even harder, in space spin gravity and private cabins are not that hard. Try combine this with landing then most passangers has no issues with seats the few hour you need to dock with the liner or orbital station.