I’m not convinced that 2x “giant” engines (even if the B-52 could fly on only one engine after getting hit by a missile or AA flak), but it is an interesting question.
The B52 has 8x small, relatively inefficient old medium bypass engines on 4x struts now. Each small engine does tend to self-shield its partner (Vietnam flak and AA missile rarely took out both engines in a pod when they were hit). But, do 8x low-bypass or 4x high-bypass engines provide more of a “target area” for debris and frag particles than 2x larger diameter engines, one on each side?
Reading the stories of each B52 shot by North Vietnamese SAM’s doesn’t seem to prove the theory either way.
My instinct says “Better 2x engines on each wing than 1x engine, since the out-of-symmetry forces and damaged ailerons and tails and flaps would make controlled flight harder after the rocket hits.”
Why?
For pure fuel efficiency in airliner use, two large engines always perform better than four smaller engines.
The Airbus A330 and A340 are basically identical aircraft except for the engines. The A330 has two, and the A340 has four.
The A330 is much more fuel efficient, and the A340 has all but died out as a result. It's only reason for being was for long range over water routes where 3 or more engines were mandatory for flight safety.
But then the ETOPS rules (Extended-range Twin-engine Operational Performance Standards, a.k.a Engines Turn or Passengers Swim,) allowed twin entine aircraft to fly these routes, killing off the A340.
As for the B-52, there has been talk for literally decades about re-engining the B-52 with either four or eight high-bypass turbofans. The latest thinking is eight small high-bypass turbofans from the Gulfstream 650 would be easier to certify than four larger turbofans under the wings.
2 engine a/c lots less maintenance costs.
All good points. And we all know that the B52 only "needs" fewer engines because of A) the global warming hoax and B) some contractor wants to build them. Someone I knew who'd been a flightline mechanic for the B52 said the engines are "pigs", a real mess after a flight. The have one job though, which is to get the job done, and they've done that over a number of iterations since they first took flight in the early '50s.