5 (five!) engine Constellation

[multiprops]

Ok, for all those (evil) people that used to say Constellations were "world best "tri-engine" 

[DaveSims]

Well you have to give us more info on this particular aircraft!  I'm guessing it is (was) used to test new engine designs in flight.

[C]

Quite a common thing in the 40s and 50s to see various engines installed on 4 engine test beds - after all, they generally had the best performance to cope with the extra weight.

Here's an interesting one (the single engine B-17's a photoshop job of the 5-engine photo!):

B-17 test beds

Avro Lancaster's tended to be a bit more interesting! As test-beds, they had engines in place of the outboards (jets and props), nos mounted props, bomb bay mounted jets and tail mounted jets! Quite a selection!

Lancaster Test Beds

[DaveSims]

I remember hearing the story about the 747 they used as the test bed for the 777 engine.  They replaced one of the inboard engines with the 777 engine.  Once they got to altitude they one at a time shut down the other engines, until they only using the one 777 engine to keep the 747 airborne.

I am still surprised that Boeing did not follow up on that test by making a two engine 747 variant, as it would seem the engineering ability is there and I would suspect it could increase efficiency.  Of course, there was always talk of re-engining the B-52 with four single turbofans, instead of the current eight engine configuration.

[multiprops]

[quote]Well you have to give us more info on this particular aircraft!