Originally Posted by Astra driver
I think the discrepancy can be explained by the fact that the 6750nm range for the '550 is at M.80 , at it's high speed cruise of M.85 it will go 6,000nm.
That's a good thought although they also mention the G450 range as being 4,220nm in the same context and obviously the G450 doesn't fly at M.90 at all and at its faster speeds it would get nowhere near that range.
Originally Posted by Astra driver
In general I find that I can expect slightly better fuel efficiency from the 650 vs my old 550, and this is an aircraft that has a significantly wider fuselage, weighs about 10% more, goes 6% faster and about 4% further.
That's the impression I had back in 2011 when the G650 was announced and it was like, "look at all this extra size and speed and the bit of extra range that they are going to get out of only ~1% more fuel per mile, isn't it impressive what they can do even with these old BR700 series engines".
Now they have the G600 coming out 8 years later with clean sheet engines and it just doesn't seem very impressive. Significantly narrower fuselage and less range than the G650/ER and saves less than 3% fuel per mile? Shouldn't they have been able to do that or better just with the narrower fuselage and optimization at lower fuel capacity, without the brand new engines? And by the way it only seems like it will use about 2% less fuel per mile than the G550, an airplane that came out 15 years earlier (or 21 years earlier if you count from the G-V).
Now this is all speculative because as we know Gulfstream and the other OEMs are all very cagey and manipulative with the information they release. For example, they listed the G650 as having 5,000nm range at M.90 until one day they announced that it would actually be 6,000nm. It could very well be that the G600 will have significantly more max range than they are currently letting on but that they don't want to cannibalize G650 sales. So if one day closer to the 2019 launch date Gulfstream announces that "Oh nevermind, the G600 is actually going to have 6,700nm range, not 6,200nm, with fuel capacity staying the same as planned" I wouldn't be surprised.