Frankvw.
I am perfectly aware that the -58 only has one engine, I was talking fleet wide, hence the plural. Probably should have chosen my words more carefully.
As to the single vs twin engine layout, at first the twin engine layout looks a lot better doesn’t it? But think about it. In what part of the flight envelope will the -58 attract most bullets….low and slow I would presume. While hovering behind some cover, or flying slow over some urban terrain. Trust me, scouting can not be done while flying fast. I fly for the police myself, and do some “scouting”..and we fly slow most of the time…as slow as we can. In that scenario one or two engines will not make much difference. If you loose and engine in a hover or takeoff phase of the mission, chances are you are going down….granted, you are landing slower and softer than having to autorotate.
Now, if the helicopter is travelling at some speed when the engine quits, you can fly home and land.
So, for that little gain, you will have to factor in a lot of negatives.
Fuelburn…it is going to be almost doubled.
Weight…one extra engine with accessories…pumps etc. All that extra weight cuts into the payload capacity, fuel load (range, time on station)
Complexity…twice as much that can fail..and we all now Murphy.
Cost, and logistics. A turbine operating in a hot and dusty envirnment like Iraq is a baby in constant need of special care. The sand is eating away the internals of the engine, and constant engine changes is the norm..that would be doubled with a twin layout.
There is a reason that scouts are single engined..they need to be cheap, small and relatively simple. In this case, that second engine is not worth the extra worries, just to be able to land a little softer in case one of them gets shredded.
And in such a small and weight limited machine, the engines are going to be right next to eachother, sharing a gearbox..so if one goes, chances are the other is not to far behind.
Ken
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