Infidel!
I actually thought about bringing up the B5 fighters as a good example of what a non-atmospheric fighter would be.
Of course, one could also argue that because the X-Wings were designed to also be viable in atmosphere, that limited their maneuverability to a certain extent.
Or, y’know, George Lucas is just kind of a moron when it comes to physics.
Scotty probably replaced those pesky suckers with small disks of gold pressed latinum decorated with some old Vulcan dude 
Didn’t you just love the submarine surfacing? It shoots up out of the water at a 45-degree angle. Pauses majestically. Then slams the nose down on the water (from the equivalent of 5 stories at least) and floats serenely. And no one’s coffee is even rippled, much less anyone’s body crushed against the bulkheads.
As much fun as the Flying Sub smacking into the water without any damage to the sub or its occupants.
Heck, Sky Captain and the World of Tomorrow did the same thing with its hybrid airplane/subs. There’s just something appealing about the idea of diving directly into the water that makes you forget about the incredible splatting forces that would result. As my cousin remarked (back when VttBotS was first on), you could conceivably land on the surface of the water, and then submerge. But that’s not as much visceral fun.
It would depend on the design of the plane/sub and the angle of entry. Conceivably it could be doable. Broadside smack up against the water, however, would not be good.
I honestly can’t see it being done at all. You’re going to have pretty extreme changes in velocity, even in the “best” of circumstances, and very extreme stresses on your craft, in any case. If you survived the plunge into the water, I’d sure as heck never trust the craft in flight again.
For that matter, the sudden cooling of all those surfaces that had, until plunging into the water, been at jet temperatures (or at least High Engine Temperatures) would induce all sorts of cracking or quenching that would result, I’d think, in the craft coming apart in short order.
I was thinking of something like wings that retract into the body and as close to perpendicular as could be managed. People have survived falling (or jumping) off of the Golden Gate Bridge that way, when they’d otherwise splat. But yeah, I wouldn’t want to think about the stress that the temperature changes would cause. (Maybe if the engines were retracted along with the wings…)
Hey, if James Bond can do it in Triumph…
On the asteroid energy change during detonation:
If the bomb was at the center of mass,it would impart a velocity vector to all parts away from itself. Those portions in front of the bomb (in relation to the motion of the asteroid in relation to earth) would have increase in forward velocity, while those behind would have a decrease. Unless you devised a directional bomb, or placed the bomb closer to the front than the back, the net effect would be to just spread out the impact over both time and area as a compact solid mass turns into an expanding group of smaller rocks. Depending on the size of both the asteroid and the bombs, this may or may not help at all.
As others have said, the best effect would be to deflect the asteroid. If detected early enough even something as relatively puny as a Saturn rocket could deflect a planet killer from hitting Earth.
Or deflect a near miss into a direct hit. Wouldn’t that be embarrassing?
Actually, for a blowing-apart asteroid, aren’t we more worried about conservation of momentum? I mean, taking all the asteroid’s kinetic energy towards the Earth, and turning it into, say, rotational energy spinning the asteroid (with only a tiny velocity towards the Earth) would conserve energy, but still vastly improve things (from the point of view of preserving the earth). [I’m going with the ‘every piece still hits the Earth’ restriction].
The problem is that we need to conserve momentum, too, so for every piece of the asteroid that’s slowed down (relative to earth), another piece needs to be speeded up.
Well, you have to conserve everything. I was only focusing on energy because it’s the total amount of energy that will determine the amount of damage it causes.
SaAve for the occasional Japanese fishing boat.
How many rounds can possibly be in the magazine of an action hero’s assault rifle? Best not to ask.
Actually, that’s not so bad. But we should never, ever see the actors fall out of their chairs. A starship that maneuvers at those speeds would have to have, not only an artificial gravity, but a complete inertia-dampening field to prevent the crew from turning into films of jelly on the bulkheads.
Why would you be exploding the bomb in the middle of the asteroid? Wouldn’t you want to aim the bombs at the bit closest to Earth?
If an asteroid impact wipes out all life on Earth, [del]does it make a noise[/del] is anyone embarassed about it?
“splatting forces”
Man, I missed out on all the fun physics when I decided on chemical engineering, didn’t I?
If I was doing the planing I would plant the bomb in an open tunnel on one side of the asteroid for maximum lateral velocity. Planting it in the front would require a bomb big enough to overcome all the energy of the asteroid. At least a bomb in the middle has a chance to deflect some of the asteroid.
Just the people in the space ship that nudged it the wrong way. Unless they were like Steve Buscmi and just along to watch the show.
Fanwank here, but how about if their inertial dampers had a sort of buffer that could be overloaded? Like, it can absorb the inertia of acceleration, but if there is also then another outside force that acts in a direction different from the acceleration, it overloads and lets a bit of inertia through, like the aforementioned circuit breakers? The big question is, why don’t they have seat belts?
In case the starship catches fire or flys into a lake or river. You wanna be trapped by a jammed seatbelt in those circumstances?