Why did they have to fly down the trench?

The close proximity of the trench walls going past gives a constant and real sense of motion and speed. Dramatic stuff, and it looks dangerously cool.

If i'm at the movies, I want to see the trench run.

However, were it real, and I was in the pilot seat, I'd much rather, as you say- drop out of hyperspace, fix the target, fire, and win.

As a pilot in real life, I can tell you that just flying slow, let alone somewhat fast while in any area with limited room to manuever, is always dangerous, not to mention nerve-wracking.

 

they did it to make a good and difficult video game stage later down the line... I'm looking at you Rogue Squadron!

 

"Because it looks seriously flippin' cool!" is the most obvious answer.

And y'know, if George had just thought to put some sort of overhang above the exhaust port, whereby the only angle that you could possibly drop a torpedo down there was horizontally along the trench, that would have made sense of the entire thing. Or, if the exhaust port opening were oriented horizontally rather than vertically.

 

Yeah, I thought the exact same thing as a kid. Why not just do vertical 360s over the target firing repeatedly until one of the shots goes in the exhaust port?

I think the special effects were limited in a way, and if they could have done so the trench would have instead been a tunnel that physically would have required a pilot to fly within it to hit the target. That's what I tell myself to justify how it turned out. Still, very exciting stuff, especially for a ten year old kid.

 

Actually, even more than Dambusters, the trench run was inspired by the movie 633 Squadron, in which British pilots attack a Nazi rocket fuel plant, which is sheltered under an overhanging cliff at the end of a long fjord in Norway. If I recall correctly, they have to skim the surface of the fjord, dodging fire from anti-aircraft guns, then perform a snap-roll up onto one wingtip just as they release their bombs, so they'll arc laterally under the overhang.

See, and here Lucas even had the overhang justification right there in one of his main source movies. Why he didn't incorporate it into the SW trench run, I'll never understand. It would have been so easy to do, and it'd have made that iconic scene make a lot more sense.

 

Way back when, I was a gunner on an M1-A1 Abrams MBT. Although designed to go toe to toe with enemy tanks, the Abrams is also capable of engaging low flying aerial targets (helis), and we received extensive training in the gunnery simulator to learn the various techniques involved.

One basic rule in the physics of anti-aircraft gunnery, is that the closer the target, the more difficult it is to hit. Say a Hind-D helicopter is passing through my field of view perpendicular to my main gun 1000 meters to my front at 150kts. The heli will appear to be travelling fairly slow, which makes it easy to acquire, range, and then engage. Have the same heli do the same thing again, only at a range of 500 meters this time, and you will find that the speed relative to you is now far faster, even though the heli is still travelling at the same airspeed. You have far less time to acquire and shoot.

At even closer ranges it becomes nearly impossible to acquire the target in time to get off a shot. And, at closer ranges, the target speed can also exceed the speed in which the turret you are in can traverse and/or elevate, basically negating any chance of making a shot.

So in general, the idea of X-Wings skimming the surface of the Death Star as low and as fast as possible, is tactically sound, and makes good sense.

 

I thought this was obvious, but the gun emplacements on the surface of the death star couldnt fire into the trench.. or I am mistaken?

I thought by flying in the trench they were putting thmeslves below the line of fire for the turbo-lasers on the surface, and that was the only way they could get close.

 

If memory serves, there were gun turrets in the trench as well. Like these-

 

Huh...

one other thing.

The death star is a planet-sized station, how would gravity affect this battle?

 

I've wondered about that myself.

 

Lots of good science going on here. You guys make me proud

I can't say I'm a pilot or I've ever practiced targeting helicopters from an M1-A1 Abrams tank, but I did teach algebra and calculus at a community college for a few years. So here's my two cents worth, from a nerdy, sciency point of view.



First, let me point out that these numbers are not realistic. For a 67 km diameter space station to weigh 19 billion tons, a person standing on the surface of the Death Star would weigh 1199.225 times as much as he or she does on Earth. Whatever the Death Star in this spec sheet is made of, it's far, far more dense than Earth's iron core. But since this is the best looking data on the Death Star's size I could find, we'll ignore the weight and stick with a diameter of 67.375 km. Since the equation for the distance to the horizon can be derived from the Pythagorean Theorem, we can plug and chug and find out just how large of a firing radius a surface mounted turret tower would have.

Let's assume a surface turret tower height of 10 meters. Since a squared + b squared = c squared, then c = square root ((67.375km +10m)-(67.357km), or just a bit over 1.1 km. Let's also assume a turret density of 1 turret per square km of surface area. Since the surface area of a sphere is 4 pi r squared, there are 14356 turret towers on the Death Star. Great, but what the hell does it mean for Luke and his friends?

It means if a target is far away enough, half of the Death Star's turrets could target it. The other half are on the far side of the Death Star and wouldn't be able to see the target. Still, that's 7,178 turrets shooting at a distant target. Ouch! The closer the target gets, the fewer turrets can see it. At 10 km altitude, every turret within 12 km (about 500 turrets) would be firing. (Don't pull up, Porkins!) At 10 m altitude, only turrets within 2.2 k could target an X-Wing, which means each X-Wing would be dodging about six turrets at any given moment. But at surface level, only turrets within 1.1 km would be able to see it. Based on our assumed density of 1 turret per square km, that means our X-Wing pilots are only dealing with two turrets most of the time. And as RBanks said, at that range the turrets have a very small window of opportunity.

Flying in a trench eliminates the surface turrets altogether. But what about the trench turrets?

Surface turrets are probably far more powerful than trench turrets, for two reasons. First, trench turrets are designed to aim at craft small enough to fit in a trench, while surface turrets are made for dealing with bigger, capital class ships. Second, a trench turret could hit the Death Star itself, and a smart designer would nerf the trench turrets enough so they won't penetrate the other side of the trench if they miss their target. So it makes sense a fighter's deflector shields could deflect away a few shots from a trench gun, but not a surface gun. I haven't watched the original Star Wars in awhile, but if I remember right, not too many X-Wings made it back home. The trench turrets did their job pretty well. If the nerfed trench guns could do that, then full powered surface turret towers would have turned Red Squadron into confetti if they stayed above the trench.

So yes, a trench run minimized X-Wing exposure to Death Star defensive fire and probably made good tactical sense.

But putting a hyperdrive engine on a large asteroid and setting the autopilot to ram the Death Star would have worked, too.

 

At one point one of the rebel pilots says, "The guns - they've stopped!" or somesuch. Then along come Vader and his two buddies. But I always thought that the alliance chose the trench because it was out of range of the cannons. For guns to fire into the trench would have risked cannon-fire hitting the Deathstar's structures themselves.

And y'all are probably too young to remember this, but I loved the Star Wars arcade game that primarily featured the trench.

Pobody, I loved your post, and I especially love your hyperdrive-engine-on-the-asteroid idea, and hope to see it in a movie! I cannot imagine that the numbers in the schematic you posted were anywhere close to correct, because we certainly didn't SEE thousands of TIE fighters and other equipment at any point in the drama. Surely the number of crew was more like 31,000, not 31 million. Most of the Deathstar was machinery, likely a good deal of it automated, so I doubt there would have been space for a massive crew.

 

Poor Porkins. RIP, Porkins!

I love how the Rebel radio guy tells them about the new group of signals as if he were telling them "You are ALL gonna DIE!"