How long could BAE keep a flying-warship monopoly?

How long could BAE maintain a monopoly on the air battlecruiser?

Until rivals combined the necessary aviation knowledge and large construction facilities; competition is expected, with infrastructure as a barrier.

BAE's advantage in the scenario is its combination of aviation experience and large-scale shipbuilding facilities. A competitor would need to bring those capabilities together. Existing infrastructure is already in demand, so new construction capacity could be required. American purchases from BAE's US facilities are imagined as an initial step before another manufacturer enters the market.