Starfleet Jedi

l33telboi wrote: Only thing that matters in space is acceleration and deceleration, velocity is not as important. You need to remember that these vessels are piloted by humans, they can't zip by the Malevolence at near lightspeed, because then they wouldn't have time to react.

l33telboi wrote: Of course we're also given some insight on maximum acceleration in the same episode. Anakin is trying to escape the advancing Ion blast and tells his men to give it all they've got, as they try to fly their ships out if said weapon's trajectory. But acceleration was not anywhere near the kilo-g area.

Mr. Oragahn wrote:One of the highest accelerations is when Anakin joins the V-19 squadron, before attacking the six Munificents.
That said, pinch of salt with that cartoonesque CGI stuff. We've seen characters like Padmé do some weird fu.

l33telboi wrote:Only thing that matters in space is acceleration and deceleration, velocity is not as important.

• • • I have read somewhere [1], that the "normal" rocket exhaust speed is only 4 km/s. But the exhaust of the VASIMR engine is with 300 km/s already 75 times as fast as normal engine exhaust.

• • • We don't know, how fast the speed of the exhaust of an Y-Wing is supposed to be or how much mass it has. But observing their small acceleration abilities onscreen and seeing their relativ small engines, it is to conclude, that their maximum speed or the speed they can achieve in an acceptable time, can't be very high.

l33telboi wrote:You need to remember that these vessels are piloted by humans, they can't zip by the Malevolence at near lightspeed, because then they wouldn't have time to react.

Mr. Oragahn wrote:One of the highest accelerations is when Anakin joins the V-19 squadron, before attacking the six Munificents.

Who is like God arbour wrote:

l33telboi wrote:Only thing that matters in space is acceleration and deceleration, velocity is not as important.

I'm not sure, that this is correct.

The ability to accelerate or decelerate is limited by the thrust of an engine. Usually, engines produce thrust by the expulsion of a high-temperature, high-speed gaseous exhaust.

• • • I have read somewhere [1], that the "normal" rocket exhaust speed is only 4 km/s. But the exhaust of the VASIMR engine is with 300 km/s already 75 times as fast as normal engine exhaust.

Alone that means, that there is no further acceleration, when the speed of the thrust giving exhaust is reached.

But it goes further. Because, according to the equation of momentum, not only the speed of the exhaust is relevant, but also the mass of it.

If the mass of the exhaust is too low, although its speed is very high, the energy to accelerate a ship may be to small to gain further meaningful accelerations. There comes the point, where acceleration is mathematical still possible, but the acceleration is so low, that it is practically meaningless.

• • • We don't know, how fast the speed of the exhaust of an Y-Wing is supposed to be or how much mass it has. But observing their small acceleration abilities onscreen and seeing their relativ small engines, it is to conclude, that their maximum speed or the speed they can achieve in an acceptable time, can't be very high.

Correct.

But nobody has said, that they would have to fly near light speed. They could have choosen a speed twice, thrice or even ten times as fast as with which they have flown and still would have had enough time to react.

l33telboi wrote:The maximum delta-v (how much a fighter can change its velocity) is at least above what's required to achieve escape velocity.

l33telboi wrote:The total delta-v for the vessels is not known however.

l33telboi wrote:That's why acceleration is more important, a ship can keep accelerating as long as it has fuel.

l33telboi wrote:And the fighters in Star Wars do have enough fuel to accelerate for quite a while.

l33telboi wrote:True enough, I suppose. But it's a non-issue, because we know they can reach speeds far in excess of what they were flying.

l33telboi wrote:The only question is why they chose not to attack at a higher velocity.

l33telboi wrote:Personally I'd chalk it up to reaction time.

Who is like God arbour wrote:Escape velocity is the speed where the kinetic energy of an object is equal to the magnitude of its gravitational potential energy. But a star ship or fighter with a respulsorlift does not have to have gravitational potential energy.

They would ascend automatically like a balloon, if they weigh nothing or nearly nothing and are displacing the air around them (as long as the displaced air is heavier than they are with an activated repulsorlift.)

No.

As I'm being told, depending on the derivation of the principle of linear momentum, a rocket can only reach a maximum speed, that is twice as fast as the speed of its exhaust.

Irrelevant if either the exhaust speed is low (no higher speeds are possible) or if the mass is low (not enough momentum is transferred to the ship to achieve meaningful accelerations).

I think, they haven't "choosen" to attack that slow. That would be stupid. The simple reason, why they haven't covered the length of the Malevolence with a higher speed to quickly reach the bridge (where they could have decelerated again) may be, that they simply were not able to achieve higher speeds, respective were not able to accelerate fast enough.

Remember, they couldn't have flown faster than 320 km/h. The B17 has had a maximum speed of 462 km/h and a cruise speed of 293 km/h. Even the Junker Ju 87 has had a maximum speed of 390 km/h and the SBD Dauntless has had a maximum speed of 410 km/h. The later two are dive bombers, which are in their role comparable to the Y-wing.

1. Concerning the operating mode of repulsorlifts:
   
   • A repulsorlift does - as far as I know - not work with thrust but is a form of anti-gravity technology. If it, as such, negates gravity, it would negates the mass of the affected ship. And in that moment, buoyancy is valid. A ship with no or nearly no mass in an atmosphere would displace air and, as long as the air has a higher mass than the by the repulsorlift reduced mass of the ship, the ship will ascend like a balloon. That effect can be controlled by reducing or increasing the amount of negated mass.
     
     That the repulsorlift needs energy to do that - and that this energy would depend on the mass of the ship and its nearness to the gravity source (it has to negate the potential energy of the ship) is not contested.
     
     And even if a repulsorlift does not negate gravity or mass, it still would somehow affect gravity and allows a ship to push itself of a gravity source through this.
     
     With such a technology, it is not necessary any more to accelerate a ship with rockets to an escape velocity.
     
     And that was my point. The fact, that these ships are able to escape the gravity pull of a planet does not mean, that its engines have to be strong enough to accelerate the ship to an escape velocity. The repulsorlift can do most of the work.
2. Concerning the maximum achievable velocity of a rocket in space:
   
   • I was been told from a physicist, that, according to the Tsiolkovsky rocket equation, the maximum achievable velocity of a rocket is round about twice as fast as the effective exhaust velocity. More is impossible.
     
     But it is irrelevant, if significant higher speeds would be possible because, as I have said already, the acceleration is important or the amount of time, a rocket would need to achieve that speed. And one thing is indisputable: The acceleration of a rocket decreases with increasing speed. A rocket will need less time to accelerate from 0 to 1'000 km/s than from 1'000 km/s to 2'000 km/s, although the difference in speed is the same.
     
     And, as I have said also already: the relevant question is, how fast the Y-wings could have accelerated. And as it seems, they were not able to achieve significant higher speeds while attacking the Malevolence. Otherwise, they would have, if they are not totally stupid, chosen a speed far higher than the 320 km/h with which they have flown along the Malevolence.
3. Concerning in-atmosphere flight and space-flight:
   
   • I have not compared in-atmosphere flight with space-flight like that. These examples were only about the speed and the remaining reaction time of the pilots - not the fundamental differences propeller driven vessels and rocket driven vessels. You should try to remember your own posts or read a whole thread from time to time to refresh your memory:
     

     • • • l33telboi wrote:

           Who is like God arbour wrote:

           l33telboi wrote: True enough, I suppose. But it's a non-issue, because we know they can reach speeds far in excess of what they were flying. The only question is why they chose not to attack at a higher velocity. Personally I'd chalk it up to reaction time.

           That's not plausible. The pilots were clones or Jedis with enhanced reaction time.
           
           They should be able to react faster than a World War II pilot, especially with computer aided targeting.
           
           Remember, they couldn't have flown faster than 320 km/h. The B17 has had a maximum speed of 462 km/h and a cruise speed of 293 km/h. Even the Junker Ju 87 has had a maximum speed of 390 km/h and the SBD Dauntless has had a maximum speed of 410 km/h. The later two are dive bombers, which are in their role comparable to the Y-wing.

           You can't compare in-atmosphere flight with space-flight like that, especially not when one plane is a propeller driven vessel and the other uses rocket engines. Put a B17 in space and it wouldn't even be capable of traveling forwards. Put a modern Jet plane in space and its maximum velocity would be dictated only on how long it can keep accelerating.

     The pilot of a dive bomber, who is pouncing on its target on the ground, has had a higher speed relative to the target than these Y-Wings have had relative to the bridge of the Malevolence. And the pilot of the dive bomber would have to draw up its plane to prevent a crash. The Y-wings could simply have flown by on the sides of the bridge. And they were Clones and Jedis and have had computer aided targeting and advanced torpedos. I think, that they should be able to do more, than a WW II pilot.
4. Concerning the thrusters of a futuristic society and modern thrusters:
   
   • I propose you look at modern thrusters and now compare them to Star Wars thrusters. You will see, that the later have many advantages. They are smaller and weigh a lot less and need less fuel. And they are more reliable - they need less maintenance and don't tent to explode every 60 flights without proper reasons.
     
     But these advantages could have costed power - and that would be acceptable because with repulsorlifts, they wouldn't need so much raw power that our rockets are needing only to achieve escape velocity.
     
     If you ask me, I would choose the Star Wars thrusters - even if they are not able to create the same amount of thrust as our modern thrusters - every day, if I get also the repulsorlift technology.

Who is like God arbour wrote:A repulsorlift does - as far as I know - not work with thrust but is a form of anti-gravity technology. If it, as such, negates gravity, it would negates the mass of the affected ship.

I was been told from a physicist, that, according to the Tsiolkovsky rocket equation, the maximum achievable velocity of a rocket is round about twice as fast as the effective exhaust velocity. More is impossible.

And one thing is indisputable: The acceleration of a rocket decreases with increasing speed.

And, as I have said also already: the relevant question is, how fast the Y-wings could have accelerated.

But nobody has said, that they would have to fly near light speed. They could have chosen a speed twice, thrice or even ten times as fast as with which they have flown and still would have had enough time to react.

If you ask me, I would choose the Star Wars thrusters - even if they are not able to create the same amount of thrust as our modern thrusters - every day, if I get also the repulsorlift technology.[/list][/list]