SSD red, ISD blue...

[Jean Paul]

Why is the exhaust of an Imperator or Victory class blue, but with an Executor class it's red?

[Gil Hamilton]

Why is the exhaust of an Imperator or Victory class blue, but with an Executor class it's red?

Cooler or less efficient engines, maybe? Not sure. Makes the thing look ominous as hell though.

[Sea Skimmer]

Probably the result of a difference in the exhaust temperature, the ISD's might have higher performance engines while the Executor, being a command ship doesn't really need to move around too much at sublight speeds and so gets away with cooler exhaust.

[Sharpshooter]

Probably - I'd have to side with Gil on this one, though. A good deal of the reasoning behind even building the things in the first place is to try and scare the enemy into submission without a battle even starting - not many would be willing to go up against an enemy force with a command ship that's over seven (or ten, depending on what you follow) kilometers long and is bristling with weapons and craft. The exhaust is icing on the cake.

[Vympel]

I still want to know why the Executor is grey in that scene in the SE of TESB when every other time its black.

[YT300000]

I still want to know why the Executor is grey in that scene in the SE of TESB when every other time its black.

Maybe the rest of the time Hoth 6 was between it and Hoth (the star).

[Gil Hamilton]

Maybe the rest of the time Hoth 6 was between it and Hoth (the star).

Well, it's definately in sunlight. After all, how could it cast those huge shadows on the Star Destroyers if it wasn't?

[President Sharky]

Hmm, the SSD in ESB always looked kinda bluish to me. It was grey all around in ROTJ, however.

[Rogue 9]

not many would be willing to go up against an enemy force with a command ship that's over seven (or ten, depending on what you follow) kilometers long and is bristling with weapons and craft. The exhaust is icing on the cake.

The Executor is 17.6 kilometers long. Canon fact as per the movies, end of story.

[Vympel]

Correction- at least ~17.6km long, lower limit.

[Rogue 9]

Correction- at least ~17.6km long, lower limit.

Ah. I stand corrected.

[Sarevok]

Maybe the SSD uses a different type of gas in it's ion drive.

[Tribun]

Ahem, maybe they only not fire their engines on full power?

I remember, when the Avenger is seen shortly before it hyperjumps, it's engines are lit orange, not blue or white. Maybe the ISD had lowered it's engine output?
It several illustrations, SSDs with blue glowing engines are seen.

Since we don't see the engines when the SSD Executor pursuits someone in the films, we can speculate, the red is simply the normal color, and when they fire them on full power, the color becomes blue.

[Sarevok]

Ahem, maybe they only not fire their engines on full power?

I remember, when the Avenger is seen shortly before it hyperjumps, it's engines are lit orange, not blue or white. Maybe the ISD had lowered it's engine output?
It several illustrations, SSDs with blue glowing engines are seen.

Since we don't see the engines when the SSD Executor pursuits someone in the films, we can speculate, the red is simply the normal color, and when they fire them on full power, the color becomes blue.

That is a good theory. IIRC blue stars are hotter than red stars. So when the gas in an ISD engine is burning at full power it becomes blue.

[Gil Hamilton]

I just think it has less efficient engines. Like Sea Skimmer commented, where does it need to go in a hurry, it's a command ship. It's not a battleship that leaps into the fray or pursues smaller ships. They have Star Destroyers for that. It really doesn't need super-effective sublight engines.

[Tribun]

I should add, that the only time the engines were red in TESB was, when the decelerate into Hoth orbit. When the Executor is flying with speed, it's engines are bright orange.

Another piece for my theory.

Also, in "TIE-Fighter" the engines of a fast-moving commandship glow hot yellow.