If I look at the notional cost of a Divine Eagle Hale UAV, I don't expect it to be inexpensive because of the cost of high performance AESA UHF modules.
I think they would be useful, but a wall of them as an airborne IADS is a stretch. Plus whilst the Divine Eagle may operate at high altitude, I think they would still be in range of specialised AAMs.
Well, cost is relative. For example, how much would a mass produced Divine Eagle cost vs a KJ-500, when considering the additional costs of the onboard personnel, consoles, and associated life support systems on the latter? A third? A quarter?
Obviously an AEWC drone would not be cheap but it would be more expendable and allow one to deploy them in a manner different to traditional manned AEWC in an environment facing stealthy aircraft.
Calling such a network an airborne IADS obviously isnt' accurate, but rather think of it more as a forward deployed, networked, and dynamic radar picket that operates at the similar "front line" as fighter aircraft do. Against a high intensity foe with stealth fighters, it would be accepted that a certain proportion of the AEWC drone picket would be destroyed, but not before they are able to offer their services to friendly stealth fighters to deal disproportionately heavier damage against opposing stealth fighter formations that lack an AEWC picket.
The way I see it, in the near future, the results of stealth fighter vs stealth fighter combat will depend on having a greater number of sensors (assuming each side's sensor quality is similar) that can be brought to bear to support friendly stealth fighters to enable the traditional first look first shoot advantage that one seeks to attain in all air combat.
Traditionally, AEW&C have had powerful sensors but they are too big and too few and too expensive to be brought near the "front lines" of air to air combat in a stealth vs stealth scenario. The AEWC drone solution would be to put the sensors as powerful or nearly as powerful onto unmanned platforms with relatively long endurance with a degree of autonomy and advanced networking such that much of their data can be directly used by friendly fighters operating on the "front lines" (though possibly with a manned AEW&C or ISR plane monitoring the AEWC drone many 100s of km behind). Such drones would be more numerous, probably a good fraction cheaper, and more importantly they would be unmanned, meaning a more satisfactory number of them could be deployed in a forward manner, but they would also suffer some losses yet still retain a degree of effectiveness -- and most importantly they don't have a dozen humans onboard that will be killed once it is shot down.
On the other hand, a YuanMeng near space airship would definitely be out of range of air-to-air missiles carried by fighter aircraft.
And its much greater operating altitude would have the advantage of a better top-down look at stealth aircraft.
And theoretically, an airship with solar panels and lithium batteries could be largely constructed from commercial technology, and therefore could be a lot cheaper than an aircraft.
Airships could certainly have a role to play in future, with the potential for long endurance and radar horizon ranges given their altitude.
But I'm not sure if their altitude would make them particularly less vulnerable to A2A missiles of the near future given airships would be fairly large RCS targets that would also likely be slower than jet powered HALE UAVs making them less able to change flight paths in response to detected threats. Of course, I'm not suggesting an airship or a HALE UAV would be expected to dodge missiles, but an AEWC airship fleet would be somewhat less dynamic than a fixed wing HALE AEWC drone fleet when considering the previous conops of deploying them in a forward position. I can definitely see a role for airships to have long endurance AEWC coverage for IADS purposes for a fixed area, like a picket of such airships performing national air defence and air defence for bases, ports, etc.
I'm also not convinced if an airship would be much cheaper than a HALE UAV -- if your argument against an AEW&C drone is the cost of the radar, it would likely have a similar cost in that regard.
