I was considering creating a science fiction game, adapting my superhero game 'High Stakes' which is available below:

http://www.mediafire.com/download.php?myyxmmjxyzd

I wanted to ensure that there were mass combat rules so not only could you have close combat but also spaceships dog fighting and even whole fleets. It struck me that a scaling system would be able to handle this. Since the system measures the ability to affect events and the endurance rather than relative strength it doesn't matter the scale of the conflict, the system could handle it.  And why stop at fleets of ships? Just how big could you go?

So far I'm thinking of having the following categories

Individual
This covers individual species, robots and small vehicles such as cars, tanks and planes.

Large
This category covers the smallest of spaceships (such as fighter ships) and a large number of individuals that make up a division of an army.

Huge
This scale covers average sized spaceships, an army, carrier sea vessels and small settlements such as villages and towns.

Vast
This scale covers capital ships (ships larger enough to carry other, smaller vessels), space stations, armadas of spaceships and large inhabited areas such as cities.

Epic
This covers truly immense structures such as rare planet destroyers, whole continents and armadas of capital ships.

Stellar
This covers planets, moons, similar stellar objects and fleets of ships.

System
This covers solar systems, usually comprising several planets, suns and all constitute satellites and technology.

Sector
This covers numerous solar systems and space empires. It covers the resources of their internal planets, their governments and their armadas of ships.

If both sides of the conflict are the same category no scaling is required. When a party is adjusting down multiply all ranks and pools by 10 for each category they go down. When adjusting up divide by 10.

For example the mercenary Zack Hark is cornered by a division of the Zarlion army. Heroically (or foolishly) he decides to stand his ground and attempt to fight them.

Zack's stats are:
Race: 20 (Keen Sight: 10, Stubborn: 10)
Identity: 30 (Marksman: 20, Dodging: 10)
Tech: 10 (Lazer Gun: 10)

The Zarlion division stats are:
Race: 5 (Gliding: 3, Thick Skin: 2)
Identity: 10 (Marksmanship: 2, Tactics: 5, Tunnelling: 3)
Tech: 20 (Artillery: 4, Armor: 6, Enhancement Googles: 5, Grenades: 5)

In this conflict we can scale either up or down. If we wish to present the struggle from Zack's point of view we scale the Zarlion army division stats down, multiplying all figures by ten. This results in the following adjustment.

The Zarlion division stats are:
Race: 50 (Gliding: 30, Thick Skin: 20)
Identity: 100 (Marksmanship: 20, Tactics: 50, Tunnelling: 30)
Tech: 200 (Artillery: 40, Armor: 60, Enhancement Goggles: 50, Grenades: 50)

If we wanted to scale Zack up his attributes change to:

Race: 2 (Keen Sight: 1, Stubborn: 1)
Identity: 3 (Marksman: 2, Dodging: 1)
Tech: 1 (Lazer Gun: 1)

Scaling has its limits. Capital ships can't target individuals or fight solar systems on their own. If all three of a units pools would drop below 0 when scaling up, then the unit automatically becomes the defender and special rules apply.

For this conflict no scaling occurs, that is both parties use their existing pools without multiplying or dividing them. The attacker need only stake 1 chip to neutralise the defender and 2 to eliminate them. The defender stakes chips to reflect his attempt to escape harm. Both parties draw a card and whoever gets the highest value wins. However the defender adds the difference in the two parties category to his card value plus the number of chips he staked.

For example if Zack were to be fired upon by a spaceship then all three of his pools would drop below 0. Both parties draw a card. Zack can spend 10 chips from his Identity pool using his ranks in dodging. The spaceship draws 8 while Zack draws 5, with the difference in size category (2) and with the chips he staked this brings the total to 17. More than enough to escape the blasts, at least for the moment.

Once this stage is done there is a chance that the defender can escape, if they so choose. If the defender drew a higher valued card they automatically escape.

For example, in the next round of the conflict the spaceship draws a 3 and Zack draws a 9. Not only does he avoid the attack he uses the confusion to slip away before the dust can settle. He has managed to escape from the conflict.

There is a further element to scaling. Several units can merge together, adding their pools and ranks together. This prevents individual units from becoming defenders.

For example  below are the stats for a Krason fighter ships (size category: Large)

Make: 6 (Weapon systems: 4, Boosters: 2)
Identity: 5 (Dogfighting: 2, Tracking: 3)
Tech: 4 (Radar : 2, Armor-plating: 2)

This would prevent a single Krason fighter ship from attacking a capital ship (size category: Vast) without becoming a defender. However, by joining with 99 other Krason fighters this group of one hundred results in the following stats:

Make: 600 (Weapon systems: 400, Boosters: 200)
Identity: 500 (Dogfighting: 20, Tracking: 300)
Tech: 400 (Radar : 200, Armor-plating: 200)

Which when scaled up to fight the capital ship this group of 100 become:

Make: 6 (Weapon systems: 4, Boosters: 2)
Identity: 5 (Dogfighting: 2, Tracking: 3)
Tech: 4 (Radar : 2, Armor-plating: 2)

So basically you could run games where you simulate characters fighting on the surface on the planet, then have them pilot ships in a space battle while capital ship bombard each other, have an armarda of ships lay seige to a planet and even run conflicts (either combat or political) between entire galatic empires.

Is this idea too crazy and big? Does the maths work? Is there something I'm over looking?

Ether,
  I think this is a decent mechanic. Just a couple of comments:
1) This post is hard to read, you switched examples without a good indication of the switch.
2) I think there should be less levels of scale. First, it is hard to imagine an entire sector working in concert. Or the kind of story that this conflict would tell. Even so, the potential for intimidating math is too high, think about reducing the number of scales if at all possible.
3) This system seems to benefit the defender, is that intentional? It seems to make sense thematically. But I wonder what it would be like if you were the attacker and so easily thwarted. How do you get around the Defender bonus?
  Have you tried this yet?

  Either way, good luck with your game man!