Relativistic Dogfighting

[Stravo]

Hi everybody,

A question that occurred to me while walking to my firm's weekly football game...I like to brainstorm whenever I have a chance for writing purposes. Here is a scenario that I don't have an answer for and maybe someone with a science foundation can answer for me.

If two groups of fighters are dogfighting in space. both groups are going so fast that soon they are dogfighting at relativistic speeds, so I know that there is some time dilation, I know that the amount of time dilation depends on how close you are to c. But the burning question on my mind is this:

If you're an admiral on your flagship, leading a fleet into battle and your big ships are not moving anywhere near c and you start slugging it out with an enemy fleet, how does the relativistic dogfight look to him and any other observers. I mean since time slows down for the pilots, does the outside observer (The admiral) notice anything weird about the dogfighting, like are the fighters simply flickering around so fast that he can't even observe them, do they show up on threat displays, etc, or does the dogfighting seem normal (al a Star Wars) to the outside observer and only the pilots note how long it seemed for them?

Does it even make sense that fighters WOULD be fighting at relativistic speeds?

Excuse my ignorance on this matter, but I can grasp some of the ideas but when it comes to the whole time dilation and outside observer thing I get a little lost and I don't think this scenario had ever been played out in any book I've read or movie. ANy help would be appreciated even if just to satisfy my curiousity.

[Darth Wong]

I don't think dogfighting at relativistic velocities (unless they're all going in roughly the same direction, so that the relative velocities are low) is possible.

Look at modern warplanes; they don't dogfight at supersonic speeds, even though they are capable of said speeds. Even in space, maneuverability drops with increasing velocity, because it's that much harder to change direction; an impulse of any given magnitude will have half as much effect on a velocity vector which is twice as large.

You can easily turn a spaceship around if we assume Newtonian impulse drive, but it will still be going in the same direction. So I see no benefit of relativistic dogfighting. Plus, I doubt you'd be able to hit anything. People tend to assume that the attacker has an advantage in a high relative-velocity situations, but honestly, there's no real difference. It's just as hard to hit a slow-moving target from a fast-moving platform as it is to hit a fast-moving target from a slow-moving platform. As Einstein said, there are no preferred inertial frames of reference.

[His Divine Shadow]

In Destinys Way there was some fighting going on at such velocities, however it also used long ranges and they pretty much looped around a blackhole and strafed each other or something.

It was even said that one coralskipper was coming in so fast that it would have been impossible to dodge or fire at with human reflexes.

[RayCav of ASVS]

I would think combat wouldn't take place in accleration, but rather at constant speed, i.e., they turn the engines off, and turn them on at critical moments

[Connor MacLeod]

This was hit upon a few days ago, but to add a few things to what Mike said:

1.) higher speeds (especially when theyre much higher than your acceleration rate) add to a more predictable path (thus making it somewhat easier for enemies to hit you at long range if/when they detect you (since you cannot change course as rapidly/readily, or easily)

2.) combat ranges tend to "open up" much farther at higher speeds, especially when you have to factor in human reaction times (if you have two opponents moving head to head at .5c, and they take 2 seconds to target and fire on each other, how much separation would they need to react within 2 seconds before passing each other by for even a single shot?)
This isn't really a problem, but obivously it can become a limitation if you don't have alot of space.

3.) Higher speeds require much more room to manuver in (to accelrate and decelerate in, as well as the requirements in #2), which can of course also be alimiting factor.

[ClaysGhost]

There's also the problem that attaining higher (and especially relativistic) speeds requires fuel to make up more of the fighter's structure. The best you could do would be to sit on a photon rocket, with an exhaust velocity of c. To attain a delta-v of, say, 50% of c the ratio (R) of fighter structure to fuel must then be

delta_v = exhaust_v * ln (1 + R)

0.5*c = c*ln(1+R)

=> R ~ 0.65.

About 65% of a perfectly-engined fighter at launch has to be fuel to reach 50% of c, and that's probably too optimistic because that particular rocket equation doesn't take relativistic effects into account. The problem is only going to get worse at higher speeds, and remember that this ratio is just for getting to 50% c, let alone decelerating after the battle and altering your velocity during the fight.

I can't see any advantages to relativistic dogfighting.

[Stravo]

Thanks guys,

I appreciate the answers and my suspicion that it would be undesirable was confirmed. It was an idea I was toying with and wondering how I would describe it in a story but now that's out so I can just do it the old fashioned way!

[omegaLancer]

Actually check out the works of Larry Niven and his Known universe. there are several example of hi relativitic combat. The first one that come to mind is two Busset Ramships ( Ship that uses instellars Hydrogen for fuel).

It was a long draw out affair, with one ship fleeing and the othe pursuing. It was fought by a comm lasers , and the both ship being destroyed when the Magnetic field of one ship killed the captain of the ship winning the battle..

also various battles were fought in the Man kszinie wars. General the Hi thrust are used to match Vectors and to allow ship to get within weapon range ( either X ray laser or missile range)..

[Patrick Degan]

Another perspective on relativistic space combat is found in the excellent Joe Haldeman novel The Forever War. In this book, galaxy travel was possible through the wormholes created by rotating black holes (referring to the then-popular mathematical solution offered by physicist Roy Kerr in 1969), but the trick was that ships still had to travel sublight to get to the "stargates" and had to decelerate out of each gate, so that relativistic time dilation piled up on the soldiers sent off to fight the Taurans. In one chapter, the troop transport on which William Mandela, the book's protagonist, is riding with his company is being tracked by combat drones launched by the Taurans. The ship has to essentially manoeuver at high sublight velocities on an evasive path in hopes of eventually losing the drones on one zigzag. The ship suffered heavy damage when one drone the size of a large ball-bearing struck the transport, which put her out of any action other than that of simply trying to survive to reach base.

Excellent book. Made very good use of the time dilation angle —by the time William Mandela survives to the end of the war, he is over 1100 years beyond the time of his birth.