[wahern]

More than hundreds, perhaps thousands, or at least hundreds in a much shorter time frame than in previous eras. Rolls Royce's firm rejection of requests to develop a new engine is the most immediate reason the A380 was canceled. IIRC, Emirates and Airbus decided to kill the A380 within days of the Rolls Royce announcement, and in any event Emirates was clear that it was Rolls Royce's decision that forced their hand. Emirates alone would have guaranteed to purchase hundreds of such engines, considering there were 4 on each plane, but in the end Rolls Royce simply had no appetite for new development of any kind, though presumably they were entertaining the idea for quite some time beforehand.

According to Emirates and some other analysts, and contrary to popular narrative, the A380's biggest competitive handicap was the generation of engines, not the mere fact they had 4 instead of 2. The engines were nearly a full generation behind when the A380 debuted, and the gap only grew over time. Engines on a 4-engine plane are smaller, meaning less drag; have narrower power bands, running more optimally at all stages of flight; and have lower maintenance costs, even at twice the number, as they're both less stressed and subject to longer MTBF requirements--losing 1 of 4 engines is much less of a problem than 1 of 2. All considered a 4-engine configuration might still be nominally less fuel efficient, but the difference was negligible given these countering dynamics and in the opinion of some more than made up by other factors favoring the A380. The hub vs point-to-point model disfavored larger planes, but the air travel market was growing and in absolute terms so too was the potential A380 market. But the efficiency gap between engine generations was simply too large to overcome.