A few questions about airlift.
Is the current airlift fleet (C-17A, C-130J, KC-30A and C-27J) effective for the quick lift of a BG or TF? Since it seems like the ARG is not suited to operating in the SCS (limited self-defence, etc) that leaves airlift as the core deployment capability.
I don't know much about air or airlift, but with the army procuring heavier systems (in which only one vehicle can be carried per C-17A) is it possible to rapidly deploy a mechanised/armoured force quickly to a conflict zone?
Any good sources on the topic would be appreciated, as well as how it may possibly be calculated easily.
Quick lift? For a Battle Group no. For a Combat Team, possibly.
Sustained? In no way.
The problem lies in a few areas. First, what range are you talking about? The KC-30, C-17, C-130 and C-27 all have significant range mismatch. The first two are capable of 'strategic' lifts, the last two are 'tactical' platforms. So if you want to deploy BG HEELER (based on 6 RAR) from Brisbane than all the aircraft can help to go to Shoalwater Bay, some can help to Darwin and only the jets can go beyond New Zealand. Now, you can hop with the props, sure - but that adds time, complexity and logistic issues.
Secondly, time. Props are slower than jets, no matter what. that has two issues - it takes longer get somewhere (reducing any form of surprise and opening up interception options) and the personnel on board are more fatigued. Air travel hurts if doing dismounted ops very soon after landing, props make it worse.
Thirdly, the loads you are talking about are massive. Take a Combat Team for starters. That's a couple of Platoons of infantry, at least a troop of armour and some engineering kit. If your CT is dismounted (and today) this is feasible. 120 odd people, 4ish ASLAV and a batch of Hawkei. That's 2 - 3 C-17s or 6 - 7 C-130. It's a (RAAF) Squadron push, but feasible. Now, take it up a level and talk a mounted CT. Now, it's still ~120 odd personnel... but 4x M1A1 (that's a C-17 each), 10 - 12 M-113 / Boxer (that's 5 - 6 C-17, maybe more depending on how the Boxer load ends up). If you want under-armour breeching and recovery assets, add a C-17 for each. That's at least 16 C-17 loads; or more than twice what the RAAF fleet can launch at once.
Noting that a CT is as small as you would want to go, which elements do you put in first? It will depend on threat - but this is going to take a while. Assuming that a C-17 breaks on at least one hop and you are looking at putting the CT into the Middle East or Butterworth northwards, that's about a week to get everthing into theatre. And to what end? There is no logistic support, aviation support, fires support (other than RAAF). Now, there might be stuff already in-theatre, but in that case why chew up the airfleet when you could just ship them?
A Battlegroup is even crazier. It's a struggle to fit a BG onto the two LHD and LSD. It's at least 14 tanks (plus at least one M88), 30 - 40 other A Veh, 3 - 6 other M1 hulls. There are 600 - 900 people but that's ok as we'll fit them around the vehicles. There may be an arty troop - that's another 2 C-17 (SPH or M-777). So we are looking at 42 C-17 missions at least; probably closer to 50. That's probably 2 weeks of maximum effort from 36 Sqn (assuming nothing goes wrong). The C-130s and C-27s do nothing here - except perhaps fly spares around for the C-17 fleet. Two weeks? You could get an ARG there in that time. So - what's the point?
Fourthly, sustainment. How do you keep this force supplied? You are talking, what 250 000 L of fuel for the BG per week? If that Arty Tp fires a couple of missions, where are their 155 mm shells coming from? Those will require C-17s, they just mass too much. The fuel might be able to come in a KC-30 - assuming that the RAAF let you convert one to carry diesel, but that's only 60kL - so you'll need that KC-30 every 36 hrs (and that doesn't begin to build up a theatre reserve).
Fifthly, the air fleet. This will chew up so much of the air fleet it isn't funny. It's not the weights (C-17s can lift 60 t all day long), it's the hours this chews up. Is it economical to chew up large chunks of hours to lift a small combat force? And as reliable as the aircraft is, and they seem awesome actually, it's going to annoy the fleet managers! Maintaining a stagger will be hard, and if only one or two have random US's than the entire operation is delayed by days and a disproportionate load falls on the remaining aircraft. This will set up a vicious cycle that won't end well. Especially when I need this fleet to keep the CT / BG sustained.
Sixthly, support. I mentioned this before, but what is this CT / BG doing? What support assets are there in theatre? Helicopters? Each Tiger Tp requires 2 C-17 and each Taipan Tp requires 3. Plus 1 for each Sqn or part thereof. CSS? Ambulances are 2 - 4 per C-17, fuel tankers 2 -3 per C-17, general purpose trucks 2 - 4 per C-17. The stores a BG or CT chews through is astounding (beyond the fuel and arty ammo above), so that's probably another 1 - 2 C-17. While the C-17 / KC-30 can return casualties to Australia, the medical element needs 1 - 2 C-17s to go into theatre. A BG doesn't just fight alone..... Also note that I'm relying on the RAAF to deal with their own logistics, somehow those C-17s have to get fuel...
Overall, while it sounds possible, and pictures from Avalon and the like of M-1s on C-17s are cool, it starts to become less possible. When you finally hit the "to what point", it breaks down completely. The CT / BG 'costs' too much to move, takes the same time as by sea and is unsupportable at the end. I didn't tocuh threat (noting other than Afghanistan or simliar land-locked areas, the ARG will always be more survivable than this air mission), but against a semi-capable threat, you'd end up with an airfleet that had been run into the ground and a whole bunch of dead Australians and equipment near some APOD...