Turn this ship around!

[ZapBrannigan]

"By Any Other Name" ends with the Enterprise doing a 180 degree turn to go home. TOS-R shows the ship turning in a big arc the way an airplane or car would.

Setting aside the imponderables of warp drive, is that how you would turn a real spacecraft around? Maybe only using little steering thrusters? It seems intuitively that turning in a arc would conserve (make use of) your forward momentum, while coming to a full stop would waste it.

But the other view is that, to turn around in space, you should cut off your forward thrust if any, rotate the ship 180 degrees so you are flying backwards, and then restart your engines to slow down, stop, and begin traveling in the desired (opposite) direction. Despite having to come to a stop, would that use less fuel?

 

[T'Girl]

Of the various theories I've heard, the "field" that reduces a ship's mass seems to describe what seen on screen the best.

 

[Timo]

It seems intuitively that turning in a arc would conserve (make use of) your forward momentum, while coming to a full stop would waste it.

If your ship obeys Newtonian mechanics, this doesn't work. Momentum is a vector quantity, which you can always split into component vectors, of which each is preserved separately. So the first case, when split into components, involves killing all of your forward momentum while at the same time applying momentum to, say, starboard, and then canceling out that momentum, and then creating the homeward component of momentum. In other words, you do all the work that stopping and reversing would involve, plus the sidewards acceleration and deceleration.

The reason gradual turns work here close to Earth is that vehicles and aircraft do not move by thrust alone. In a road turn, the wheels create sideways friction that kills your forward momentum "for free" when you turn your car sideways on the road; a spacecraft doesn't have wheels and has to do this killing with the engines. In an aircraft turn, wings create lift that can be applied to kill forward momentum, and indeed turn the forward movement into lift that creates a force vector that, when the aircraft banks, can adjust direction instead of just fighting gravity; again, spacecraft don't have wings.

Why a Trek starship might wish to turn in a graceful arc might have more to do with the starship not wanting to turn sharply in the first place. Rather, it just rules local space by pointing its nose whichever way, and the fact that its impulse engine is at full thrust all the time (as opposed to most rocket engines) makes its movements more arcing than pivoting.

Turning on a dime might be considered "pennywise": if a starship wants to withdraw from a threatening location ASAP, the sharpness of the turn is immaterial, because the only thing that really matters is the acceleration available from the engines - and at thousands of gees for impulse, and supra-zillions of gees for warp drive, it makes turning at a few dozen degrees per second a tactically meaningless addition to the maneuver.

Timo Saloniemi

 

[Kor]

But the other view is that, to turn around in space, you should cut off your forward thrust if any, rotate the ship 180 degrees so you are flying backwards, and then restart your engines to slow down, stop, and begin traveling in the desired (opposite) direction. Despite having to come to a stop, would that use less fuel?

In the game "Starfleet Command" (based on the old "Star Fleet Battles" wargame with millions of rules), the 180 degree turn was kind of an emergency maneuver. It took more energy, and you had to wait a certain amount of time before you could do it again.

Yeah, it's questionable to try shed light on the series by looking at games... but SFB and SFC were very well thought-out, so I think it might make sense in this instance.

Kor

 

[Metryq]

Since both types of engines (impulse and warp) are shown to have inertial effects only when it's funny, er dramatic—

—such as when dodging enemy photon torpedoes, or doing the time warp, the writers can do anything they want. Any banking or aircraft-like maneuvering is a concession to the audience because it is what they expect to see. This is like the "swish" of the Enterprise passing, as quoted by Stephen Whitfield in THE MAKING OF STAR TREK.

In "reality," the ship would move so fast it would appear to blink out of existence, or flash away as a streak, as some VFX artists have imagined. If the ship had to deal with "normal space" inertia when pulling a 180, drifting, or doing a Rockford, Starfleet would be pulping crews faster than it could replace them.

(Actually, one of the earliest warp drives assembled by Cochran burned rubber on the continuum so hard its effects ran backwards in time. Now you know why we have Leap Years.)

 

[BeatleJWOL]

In "reality," the ship would move so fast it would appear to blink out of existence, or flash away as a streak, as some VFX artists have imagined.

That's one of the things I love about the (light the pitchforks, kids!) NuTrek warp effect. It's just BOOMgone.

 

[ZapBrannigan]

Since both types of engines (impulse and warp) are shown to have inertial effects only when it's funny, er dramatic—

"No, not at any time..." That's a great scene.

The reason gradual turns work here close to Earth is that vehicles and aircraft do not move by thrust alone. In a road turn, the wheels create sideways friction that kills your forward momentum "for free" when you turn your car sideways on the road; a spacecraft doesn't have wheels and has to do this killing with the engines. In an aircraft turn, wings create lift that can be applied to kill forward momentum, and indeed turn the forward movement into lift that creates a force vector that, when the aircraft banks, can adjust direction instead of just fighting gravity; again, spacecraft don't have wings.

That's the essence of why the TOS-R scene with the graceful arc is more aircraft than spacecraft. When they're going one way and Kirk suddenly says "Turn this ship around," the Enterprise should do something more like an Emergency Bat Turn:

https://www.youtube.com/watch?v=vBIdzSt2UZ8

 

[plynch]

I liked the effect in nuTrek, and I'm not a fan in general. But it seems more drastic as FTL seems it should be.

 

[ZapBrannigan]

I liked the effect in nuTrek, and I'm not a fan in general. But it seems more drastic as FTL seems it should be.

The re-imagined Battlestar Galactica series beat them to it by at least five years. That show had fantastic fx in general.

 

[Metryq]

I liked the effect in nuTrek, and I'm not a fan in general. But it seems more drastic as FTL seems it should be.

The re-imagined Battlestar Galactica series beat them to it by at least five years. That show had fantastic fx in general.

And the arcade game Asteroids was years before that. There was also a space battle game with the same physics that had a ship that looked like the Enterprise. If I'm remembering correctly, the other ship was an Imperial Battle Cruiser, like in Asteroids.

 

[Elder Knight]

Although I can't say just where, I recall that one of the comic books has Kirk ask Sulu for a 360 degree turn. That would be taking "turn around" too literally.

 

[Richard Baker]

Although I can't say just where, I recall that one of the comic books has Kirk ask Sulu for a 360 degree turn. That would be taking "turn around" too literally.

"Sulu smiles, pretends to touch a button and says "Done, sir!"

 

[Hatshepsut]

The reason gradual turns work here...is that vehicles...do not move by thrust alone. In a road turn, the wheels create sideways friction that kills your forward momentum "for free" when you turn your car sideways on the road; a spacecraft...

...has nothing external to react against, like the road for the car. Nicest formulation of this problem I've seen.

...and at thousands of gees...

...but if things are to be Newtonian, I'm afraid I'll have to decline this roller coaster ride. The Colossus at Lagoon only reaches about 2.5g.