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I was thinking about how slow combat speeds in Star Wars seem, and it occurred to me that if they were moving at anything like their high-end speeds they would have been able to circumnavigate the entire 500km circumference of the first Death Star in literal seconds.

I then realized that the trench they are traveling down is the polar trench that runs less than a 1/4th of the total distance, at which point I also noticed that we have an explicit number for the time it takes. Luke goes into his final trench run when the Death Star is one minute away from firing and makes it into firing position at exactly the right time.

Anyway, if this trench is 1/4th the total circumference of 500 km and it takes one minute:
with d=1/2a*t^2, a=2*d/t^2

That would mean that during the trench run Luke's X-wing had an acceleration in the ballpark of 7Gs. It's probably closer to 1/8th the total distance but I was being conservative because he would also presumably need to slow down for the final shot (when Vader catches him).

Not looking at this in the context of any debate or anything, I just found it interesting.

A small question, but where does 500 km come from? While not part of the movie of course, but when the Death Star was upscaled from a smallish sphere with large windows, Ralph McQuarrie calculated that it was 150 km in diameter with a one mile wide equatorial trench. I can't recall any source placing DSI at 500 km and I can't recall any such discussion here.

Mange wrote: ↑2024-02-28 02:26am A small question, but where does 500 km come from? While not part of the movie of course, but when the Death Star was upscaled from a smallish sphere with large windows, Ralph McQuarrie calculated that it was 150 km in diameter with a one mile wide equatorial trench. I can't recall any source placing DSI at 500 km and I can't recall any such discussion here.

Calculate the circumference of a sphere or circle - 2πr

r = 75
2 * 3.14 * 75 = 471.24.
I believe he was rounding up.

Or he may have been using the 160 km diameter that has been floating around in, among others, the old ICS books - this would give a circumference of 502 (and change) km.

Eternal_Freedom wrote: ↑2024-02-28 12:22pm Or he may have been using the 160 km diameter that has been floating around in, among others, the old ICS books - this would give a circumference of 502 (and change) km.

Yes, that is what I was using. I also rounded off at 500 because it was a nice easy number and the difference didn't matter much.

Just out of curiosity I redid it with the smaller diameter of 120 km that has also been used and you instead get 5.3Gs.

Either way it doesn't make a huge difference. These numbers are really only good to an order of magnitude anyway. I also suspect the actual acceleration is at least somewhat higher because they likely accelerate faster during the run and then decelerate to fire their torpedoes. While he catches the Y-wings fairly easily, Vader only catches the faster X-wings at the end when they are lining up their shots (both Luke and Red Leader).