Gulfstream to announce new jet Oct 14 2014

[Astra driver]

Tuna,

I also noticed the discrepancy in the range quotes for the G550, 6,000nm vs 6750nm. (The latter is the correct maximum range)

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.

Since I think the article was attempting to make an apples to apples comparison it compared the range of the slowest cruise speed of the G600, M.85 to the range of the highest cruise speed of the G550.

I suspect the meager improvements in fuel efficiency you illustrate on the 600 vs the 650ER are due to the fact that the engine/wing/fuselage design was optimized for the G500 and that said design was then stretched to give it a 550 type cabin and range which resulted in the corresponding loss of efficiency. Notice that the 600 carries 9,910 lbs more fuel than the 500, as a rule of thumb I find that you can expect to burn about 4% per hour of that extra fuel carried, hence on a 12 hour flight you can expect about 1/2 of that extra fuel to be burned just to carry it. No doubt this will cause a big hit to the aircraft's efficiency. If you were to load the 600 up with the same payload and fuel as the 500, I suspect you would see much closer efficiency.

Having worked in the private biz jet industry for 15 years now, I can tell you that the last thing on the mind of owners is fuel economy, they may go nuts over the fact that the flight crew went $5 over the meal allowance the night before, but are oblivious to fuel costs.

Also the BR725 engines on the 650, while based on a 20 year old design are quite different from their predecessors, a one piece machined fan up front with scimitar blades, time between overhauls increased from 8,000 hours to 10,000 hours and the previous 4,000 hour mid life inspection has been completely eliminated.

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.