All my previous evidence summarized/edited for current HA theories:
In all honesty it feels like Ork cruisers should cost about 10 pts less than they currently do. With the Smotherman formula this equates out a Kill Kroozer to be 145 points, and terrors costing 175.
Mathematically 6 bombers attacking an ork cruiser results:
6.875 hits Ouch, especially when compared to an imperial or chaos cruiser, which only 2.5 hits are caused. At three they would suffer 1.125
Escort math:
Note: This doesn't account for the Brutes ramming capacity, which is indeed another factor, but for this it is ignored.
The Onslaught:
Ability to engage enemy/Maneuverability: Brute>Onslaught by 79.2%
Firepower: Onslaught>Brute by 25%
Hits/Shields: Brute>Onslaught by 40%
Average: Brute>Onslaught by 19%
Possible solution here:
Increasing the Onslaughts FP to D6+1 would make Brute>Onslaught by only 4%
Further Reducing costs: At 30 Brute>Onslaught by 5.8%
Vs a sword
1 bomber has a 33.6% chance of killing an onlslaught, 2 would have 58.3% chance. Compared to the sword 1 would have a 10.5% chance, 2 would have a 26.8% chance.
1 torp from the front will kill an ork 8.8%% of the time, whereas from the side 25%, a sword would die from the front/sides 8.325% of the time.
1 ac=25% chance of killing onslaught, 2 have 56.25% with the sword; 12.5%, and 37.5% respectively.
Strangely an Onslaught is 50% as survivable against ordinance as a sword.
Hits/Survivability (Incorporating ordinance, and general playstyle): Sword>Onslaught by 44%
Firepower: Sword>Onslaught by 14%
Maneuverability/Area of Aquisition/Speed: Sword>Onslaught by 125%
Overall: Sword>Onslaught by 61%
Increasing firepower of onslaught by 1: Sword>Onslaught by 52.6%
Ships in fleets:
TS: 92% of fleets (78% had at least 2)
KK: 64% (23% had at least 2)
Slamblasta: 5%
Kroolboy: 0%
Gorbags revenge: 7%
Deathdeala: 31%
Hammer: 35%
Ramship: 54%
Onslaught: 7%
Ravager: 62%
Savage: 34%
Roks: 24%
warlord upgrades,
Powerfields: 42%
Mad Meks: 0%
Looted Torpedos; 28%
Maniak gunners: 0%
Mega-armor: 14%