Big Ships Go Boom: Experimental D&D4E Air Combat

For the semester finale of the D&D4E campaign I'm currently co-DMing, I decided I wanted to do something a little bit different from normal. Drawing inspiration from equal parts the Avatar: TLA finale, the airborne sections of Gears of War 3, and tabletop Warhammer 40k, I gave my players each an airborne warship, set them adrift amongst roughly 40 or so enemy warships, and let them wreck havoc.

Overall, I thought it went surprisingly well. Because every character was "identical" and the possible actions were limited to about 3, combat went smoothly and quickly. In addition, because the die rolls were always standardized and no math was involved (only checking a small chart) people caught on very quickly and nobody ever flagged. I think it was a much-needed breath of fresh air in terms of how combat normally went, and a really cool new thing for my players that also gave them a chance to wreck serious havoc (their final kill-count was 24 ships at 32 people per ship). I figured I'd share the rules I came up with, in case anyone has feedback or wishes to adapt them for their own use. Enjoy!

Kalin Warship Rules

Kalin has modified a fleet of the standard airship design with one purpose: eliminate all enemy forces and deliver soldiers to the ground. 

Speed: 3 squares/turn

Weapons:

Explosive Cannons x 4 (one on each corner, can swivel 210º), Range 10

Fire-bombs, deploy from bottom of airship

Capacity: Crew of 12 (Captain, navigator, helmsman, 2 per cannon, 2 bombardiers)

 + 20 soldiers and their equipment

On a turn, the warship may move its speed and fire all weapons. To determine cannon hit, roll a d20; 11 or above is a hit. If ship is adjacent to target, 6+ is a hit.

On a hit, roll on the following chart

Hit Chart (d6)

1 - Cosmetic Damage

2 - Some crew/passengers killed

3 - d4 weapons destroyed

4 - Engine destroyed

5 - Balloon punctured

6 - Explosion!

Instead of the above, warship may concentrate all power to boost; it cannot fire, but instead may move 2x its normal speed (6 squares) and attackers must roll 16+ to hit instead of 11+

Barring a Hit Chart result of 6, crew may escape using their parachutes, while passengers are SOL. Ships also contain ropes to fast-rope soldiers to the ground, as well as grappling hooks for boarding actions. 

If engine is damaged or guns damaged, if GM deems damage reparable crew can be assigned to attempts repairs: 15+ equals a successful repair (one gun restored or +1 movement speed restored) and this number can be decreased with more crew assigned.

[Notes: for purposes of this combat turns lasted approximately 3 minutes instead of the usual handful of seconds, and ships were assumed to be moving at roughly 60 mph, meaning the "3 squares per turn" represented a much large distance than normal. The ships themselves, although combat was never held on them, were roughly 10x20 "traditional" squares in size on the top deck.

Although enemy ships rolled on the same hit-chart as the PCs, the results were usually downgraded: for instance, instead of d4 weapons it was always 1, instead of engine destroyed speed was reduced to 1, etc. Although almost all PC ships took damage only 1 was completely destroyed, and he managed to make it aboard a friendly vessel as his ship slowly sank downwards.

Firebombs, if a ship managed to get above another ship, were an automatic hit.]

-HTMC