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Ok I have a question when they talk about attack speed in in ANH. It's a lot slower than interplantary speed but how much slower.

Same reason why modern aircraft also slow down for combat. You slow down to a speed which allows for manuevering and dogfighting. The faster you move, the harder it is.

Thanks but I actually already knew that I was actually wanting to know how much slower.

Actually if we're to take the movie dialogue at face value, they have to go FASTER than when they approached the death star (clearing Yavin in a matter of moments) because Red Leader's order is "Accelerate to Attack Speed."

Actually if we're to take the movie dialogue at face value, they have to go FASTER than when they approached the death star (clearing Yavin in a matter of moments) because Red Leader's order is "Accelerate to Attack Speed."

That's the thing that was bugging me. Wasn't it said somewhere, though, that they might have had to decelerate to pass through the Death Star's shielding? They might have been forced to cut down to a measly one or two hundred meters a second, then shot up to something more respectable once they cleared it.

Anyway...

According to Mike's calculations, the Rebel force that was approaching the Death Star in ANH was doing so at about seventeen thousand meters a second, and I'm inclined to think that they'd have cut down to speeds of about five, six, seven hundred to a thousand meters a second, the lower area of that range reserved for dogfighting, the higher probably only allowing for the trench run and missile strikes. It's a cut by an order of magnitude by one, and an actual decrease to a measly 24th of cruising speeds.

Of course, given that there were also several pokey Y-Wings in the flight, it's possible that the force could have achieved even greater speeds had it been composed purely of X-Wings.

They also slow down because there's a limit to human reaction speeds, why we don't see more alien pilots I have no clue. According to TPM there are alien races more dexterous than humans and make better pod racers, don't see why they wouldn't be amazing pilots.

The Rebels were probably accelerating "to attack speed" as they approached the Death Star to cut back on the amount of time the DS had to engage them at long-range, or launch fighters to intercept the flight short of the DS. The Rebels didn't know Tarkin wasn't going to launch starfighters, after all; and one would hope they wouldn't ASSUME the commander of the DS was arrogant enough to fail to do so as part of their mission planning.

The idea was probably to cover the space between Yavin's moon and the DS as quickly as possible, slam on the brakes to cross the shield barrier, then accelerate back up to a sufficient speed to allow combat once they were inside the shield.

Remember folks, "accelerate" can mean "decelerate" too; technically any change in speed is an acceleration, whether you are speeding up or slowing down or turning or what have you.

Sharpshooter wrote:According to Mike's calculations, the Rebel force that was approaching the Death Star in ANH was doing so at about seventeen thousand meters a second, and I'm inclined to think that they'd have cut down to speeds of about five, six, seven hundred to a thousand meters a second, the lower area of that range reserved for dogfighting, the higher probably only allowing for the trench run and missile strikes. It's a cut by an order of magnitude by one, and an actual decrease to a measly 24th of cruising speeds.

We can actually get a hard value for the relative speeds the fighters were doing in the trench due to the countdown on the targeting computer. It's not terribly fast.

My guess is that the snub fighters had to go somewhat slower to penetrate the Death Stars shields, a-la Dune shields. If they hit the particle shields too fast they'd be smashed. Then once inside the shields they acclerated to attack speed to avoid the turbolasers.

Accelerate can acutally mean a change of direction not just speed but meh or maybe thats velocity. I really don't remember.

Meest wrote:They also slow down because there's a limit to human reaction speeds, why we don't see more alien pilots I have no clue.

There was at least one in an X-Wing that was removed from Jedi. I believe images are on Behind the Magic.

The Silence and I wrote:Remember folks, "accelerate" can mean "decelerate" too; technically any change in speed is an acceleration, whether you are speeding up or slowing down or turning or what have you.

Doh! I guess I missed that part of physics class. Checking the handy online dictionary it says the word can mean a "change in velocity" or an increase in speed. Decelerate means a decrease in velocity or to slow down the rate of advancement. Thanks for sharing that. ; )

Sharp-kun wrote:

Meest wrote:They also slow down because there's a limit to human reaction speeds, why we don't see more alien pilots I have no clue.

There was at least one in an X-Wing that was removed from Jedi. I believe images are on Behind the Magic.

I've got BTM, I'll have to look for that when I get a chance. If you know what section it's in though that would help...

Sharp-kun wrote: I've got BTM, I'll have to look for that when I get a chance. If you know what section it's in though that would help...

Can't remember. It was the species that is similar to the wookies, there was on in the Rogue Squadron books, was shot down in the Bacta War. Shi something.

Sharp-kun wrote:

Sharp-kun wrote: I've got BTM, I'll have to look for that when I get a chance. If you know what section it's in though that would help...

Can't remember. It was the species that is similar to the wookies, there was on in the Rogue Squadron books, was shot down in the Bacta War. Shi something.

I think the race you're referring to are Shistavanen (wolfmen) one of which you can see in the Mos Eisley cantina scene in ANH (the wherewolf looking dude).

Sharp-kun wrote:

Meest wrote:They also slow down because there's a limit to human reaction speeds, why we don't see more alien pilots I have no clue.

There was at least one in an X-Wing that was removed from Jedi. I believe images are on Behind the Magic.

Then, there's the Sullustan fighter pilot (B-Wing?) that was in the rebel briefing scene?

NRS Guardian wrote: I think the race you're referring to are Shistavanen (wolfmen) one of which you can see in the Mos Eisley cantina scene in ANH (the wherewolf looking dude).

Thats the one. I'll dig out BTM and see if I can find the image.

Old Plympto wrote:

Sharp-kun wrote:

Meest wrote:They also slow down because there's a limit to human reaction speeds, why we don't see more alien pilots I have no clue.

There was at least one in an X-Wing that was removed from Jedi. I believe images are on Behind the Magic.

Then, there's the Sullustan fighter pilot (B-Wing?) that was in the rebel briefing scene?

I think that was Nien Nunb, Lando's copilot.

No, the B-wing pilot was Ten Nunb. I think the only place you can still see him in in the briefing room.

Just examined the trench run clips (Gold Leader's run and Red Leader's run). The total time when Gold Leader's targeting computer is shown is 57 frames. The total sequence that Red Leader's targeting computer is shown (from first showing to reaching the exhaust port) is 773 frames.

Gold Leader
Gold Leader's targeting computer readout goes from 047830±10 meters (presumably meters, since centimeters is clearly too small, and kilometers is clearly too large) to 042230±10 meters. Total traversed distance in that span of time is thus 5600±20 meters. The DVDs are presented at 23.976 fps, or 41708 microseconds per frame (according to VirtualDub), equating to 57*41708 = 2,377,356 microseconds or 2.3774±0.001 seconds. 5600 meters/2.3774 seconds ≈ 2,400 (2,360±20) m/s average in that period.

Red Leader
Red Leader's targeting computer readout is broken into several segments, since we see clips several times. The first segment is 42 frames, the second segment is 40 frames, the third segment is 31 frames, and the fourth segment is 38 frames.

Segment 1:
TC1: 029090±10
TC2: 024968±10
TCd: 4122±20 m
42 frames * 41708 µs/frame = 1751736 µs
4122±20 m / 1.7517±0.001 s ≈ 2,400 (2353±20) m/s

Segment 2:
TC1: 017850±10
TC2: 013969±10
TCd: 3881±20 m
40 frames * 41708 µs/frame = 1668320 µs
3881±20 m / 1.6683±0.001 s ≈ 2,300 (2326±20) m/s

Segment 3:
TC1: 009968±10
TC2: 006968±10
TCd: 3000±20 m
31 frames * 41708 µs/frame = 1292948 µs
3000±20 m / 1.2929±0.001 s ≈ 2,300 (2320±20) m/s

Segment 4:
TC1: 003100±10
TC2: 000000
TCd: 3100±10 m
38 frames * 41708 µs/frame = 1584904 µs
3100±10 m / 1.5849±0.001 s ≈ 1,960 (1956±10) m/s

Overall:
TC1: 029090±10
TC2: 000000
TCd: 29090±10 m
773 frames * 41708 µs/frame = 32240284 µs
29090±10 m / 32.240±0.01 s ≈ 900 (902±10) m/s

The average speeds there show a continuing decrease in actual speed (though not a great one). What really bothers me is that the average speed is much different than the more specific readings. I chalk this up to simultaneous cutting in the movie. The other values are much more self-consistent, so this overall average must give way to them.


Luke Skywalker
Luke, of course, also made a trench run, during some of which we see his targeting computer. We also know that he was going in at full throttle, which the other pilots had not done (ref Biggs: "Luke, at that speed will we still be able to pull out in time?"). Given that "full throttle" in space would mean that you're accelerating at maximum capability, we should see a continuing increase in Luke's speed, according to his targeting computer.

As with Red Leader, Luke's views of his targeting computer were broken into segments -- two, to be exact -- before Obi-Wan interjected and Luke switched off his targeting computer. These segments lasted 39 frames each.

Segment 1:
TC1: 036720±10
TC2: 032970±10
TCd: 3750±20 m
39 frames * 41708 µs/frame = 1626612 µs
3750±20 m / 1.6266±0.001 s ≈ 2,300 (2305±20) m/s

Segment 2:
TC1: 024600±10
TC2: 020850±10
TCd: 3750±20 m
39 frames * 41708 µs/frame = 1626612 µs
3750±20 m / 1.6266±0.001 s ≈ 2,300 (2305±20) m/s

Overall:
TC1: 036720±10
TC2: 020850±10
TCd: 15870±20 m
279 frames * 41708 µs/frame = 11636532 µs

15870±20 m / 11.637±0.01 s ≈ 1,400 (1364±20) m/s

Same problem with the overall average being inconsistent with the other two, so once again, chalk it up to simultaneous cutting.

In any case, it's rather annoying to note that Luke's speed is not changing at all, despite being at "full throttle." Worse, it seems to be lower than Red Leader's top achieved speed (though that could simply be because Red Leader had already built up a higher initial velocity).

Additional Observations:
In both segments, Luke seems to be achieving about 100 meters/frame (≈2400 m/s), since the targeting computer hundreds digit changes every frame and never jumps a number or remains on a number in any set of frames.

Conclusions
It seems reasonable to suggest, at least from these numbers, that typical starfighter combat takes place at ≈2,300 m/s velocities (relative to a common "static" frame of reference, such as the Death Star). For those curious, 2,300 m/s = 8,280 kph ≈ 5,145 mph. Modern military aircraft attain airspeeds of roughly Mach 2, or 662 m/s (at 0°C), suggesting spatial combat speeds at speeds at least four times faster than modern air combat.

Quick addendum. I put each frame's TC value into Excel for the three different pilots and then charted those. They provide almost perfect linear graphs (i.e. almost perfect constant velocity). The average speed of each pilot over their depicted TC run is below:

Luke (X-wing):
Travels 7510 m in 77 frames
≈2340 m/s (8420 kph, 5230 mph

Red Leader (X-wing):
Travels 14100 m in 148 frames
≈2280 m/s (8210 kph, 5100 mph)

Gold Leader (Y-wing):
Travels 5630 m in 57 frames
≈2370 m/s (8530 kph, 5300 mph)

Man that seems really slow when you think of the acceleration these ships are capable of. Considering according to the site star war ships have acceleration of 3500 g's thats 35000 m/(s*s) so one sec of full throttle would blow them away.

Most likely the writers forgot to take that into affect. But then alot of sci-fi shows do the same thing. They go from planet to planet really quickly but when it comes down to close range fighting they forgot these ships are alot faster than they think or show.

dragon wrote:Man that seems really slow when you think of the acceleration these ships are capable of. Considering according to the site star war ships have acceleration of 3500 g's thats 35000 m/(s*s) so one sec of full throttle would blow them away.

Most likely the writers forgot to take that into affect. But then alot of sci-fi shows do the same thing. They go from planet to planet really quickly but when it comes down to close range fighting they forgot these ships are alot faster than they think or show.

Speeding towards the exaust port at 3500 g's isn't going to make hitting it very easy, especially when they're entering the trench with only 30 km of distance to cover.

Imagine dogfighting using line of sight (since they were being jammed to hell and they even mentioned not picking up the TIE fighters) at 3500g acceleration. Try following and locking on to something that will be out of your vision so fast with any speed change.

They may have been going "full throttle" so to speak, but full speed of attack speed. It's like a modern fighter putting on their afterburners trying to navigate through a downtown type area between buildings, just can't be done with human reactions.

Actually, I'm surprised by how fast this is. By watching the walls of the trench it looks more like 100 m/s or so; it is very blurry but I swear it looks slower than 2 km/s
Meh, nice work there McC, a good analysis.