That feels like an "apples & oranges" comparison. The Blackbird had a high-speed dash mission (and was not a VLO configuration) whereas the RQ-180 was designed for stealthy loiter capability and real-time data transmission.
Disagree. Blackbird gave a "target is
not aware they're being watched in time to get items of interest under cover" capability comparable to what a VLO/ELO ISR drone could do.
If they were still in service (I believe it'd be possible, as each flight re-heat-treated the entire airframe), blasting along [insert country name] ADIZ edge or national airspace edge to get information snapshots is still a useful capability. And they'd have the real-time datalink, simply because that wasn't an available technology when the Blackbirds were built.
How many Blackbirds were mission-ready at any given time and how much did it cost to fly each sortie?
I'd guesstimate 1/3 of them. Cost per sortie is basically a non-issue, as the Blackbird's competitor for intel was
satellites, at 2025-dollar costs of billions each including launching costs (based on Hubble, probably 125mil just for the satellite). Also, given that spy satellites are on sun-following orbits, passing over the same place on earth at the same time every day, they're not exactly persistent.
For what it's worth, there may have been as many as 25 RQ-180 airframes built. One of the nine preproduction models was reportedly lost in a crash in 2016 and I wouldn't be surprised if at least some of the dedicated test aircraft had been retired.
And the USAF had 32x Blackbirds. Assuming that the preproduction airframes were refitted to full capability the same way that the B-2s were, that would bring us down to a maximum of ~24, likely under 20 if the early test airframes were retired, best case scenario.
It'd take an RQ-180 mission-ready rate of ~50% to equal the number of Blackbirds the USAF had available for missions, under that best case scenario. MRR of 70% or more in the worst case scenario of no preproduction airframes refitted.
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'fridge' and 'hydrate' and the US tendency to not be nearly random enough in codeword selection make me wonder if it's an icing test and the aircraft we're hearing is the spray tanker.
Is it possible or probable that the B-21 is doing icing testing? just as a stupid question.