Magoo has hit on a good point there, the RAAF planned to operate a single fighter/bomber type, the F-35A. Now that seems to be going out the window with a possible two tier structure.
Actually we wont be going with a two tier structure, atleast not for very long.
I'll confirm a few things here.
The current order of 24 Super Hornets will be spread over
TWO squadrons. 12 aircraft per squadron means that each individual aircraft will be flown often and they will have very high flight hours by 2020. At around 2020 we will probably still be receiving the F-35.
I've asked around and here it is...
The Plan
Our 24 F-111's will be retired for when the 24 Super Hornets arrive. The F-111's will be replaced 1 for 1 with Super Hornets. This will happen around 2010. Squadrons 1 and 6 will be converting across from the F-111 to the Super Hornet.
Our 60 odd Classic Hornets will be retired for when the F-35 arrives. Again the Classic Hornets will be replaced 1 for 1. This will happen around 2015. Squadrons 3, 75 and 77 will convert across to the F-35.
Our 24 Super Hornets will be retired for additional F-35. Again they will be replaced 1 for 1. This will happen around 2020. Squadrons 1 and 6 will then convert across to the F-35.
The Goal
By 2025 the goal is that we will operate around 80 F-35's. Squadrons; 1, 3, 6, 75 and 77 will now all fly the F-35. Thats 5 squadrons and 16 aircraft per squadron which is spot on.
Why more Super Hornets?
The rumour behind the purchase of a second batch of Super Hornets is because the F-35 may experience delays and/or the CBR program may run into problems. If the F-35 is delayed by a year or two then the classic hornets will struggle to last even with the centre barrels replaced. By converting one of the classic hornet squadrons over to second batch of Super Hornets it will allow the remaining two classic squadrons to fly for longer and transition smoothly over to the F-35.
If the CBR runs into severe problems then the Classic Hornets will not last until the F-35 arrives. Additional Super Hornets will allow one Classic Hornet squadron to convert to Supers. This should allow the non rebarreled Classic hornets to last until the F-35 arrives.
If the F-35 is delayed or the CBR program runs into problems then the first batch of Super Hornets will see even more flight time. Remember the first batch of Super Hornets have to last until the last batch of F-35's arrive. The Super Hornets may struggle to last if the 12 aircraft per squadron is retained. This is why if a second batch of Super Hornets is purchased due to these delays it will purchase 24 aircraft instead of 12. So instead of operating 12 aircraft per squadron it will now operate 16 aircraft per squadron. This will allow the Super Hornets to last out until 2030 which should be plenty of time for all the F-35's to arrive.
So in the end Australia will be flying F-35's only.
The Super Hornet is a transition aircraft only.