I'm sure that Gulfstream has looked at the idea of using LE devices with each new design but if you consider the two most recent designs, ie the G5/550 and the G650, both required the use of a large wingspan design to meet their very long range cruise requirements (6,500/6750 and 7,000nm respectively). By default this large wingspan will produce low t/o and landing speeds and hence largely negates the need for LE devices. For reference, I typically see Landing Ref speeds on both the 550 and the 650 in the 113 to 118 range.
As for takeoff performance, after reading how a Falcon can loft 5 hours worth of fuel out of LCY, I was curious what a 550/650 could manage out of a similar, sea level 4,800 ft strip on a 30 C day and enroute at ISA + 10
G550 : MTOW 80,000 lbs, enough to carry 5 pax 3,400 nm at M0.85 (7.5 hrs)
G650 : MTOW 85,000 lbs, enough to carry 5 pax 4,300 nm at M0.85 (9 hrs)
(As for landing, max landing weights for 550/650 are 75,300/83,500 respectively, still enough for 6 hours/8.5 hours and well within 4,800ft)
And yes I know that Gulfstreams can't LAND at LCY due to the fact that they are unable to meet the steep GS requirements without deploying flight spoilers which is currently prohibited with landing gear down per the AFM, although Gulfstream is rumored to be working on an ASC for the '650 at least to allow this.
No question the Falcons, Bombardiers, etc are all great aircraft in their own right, and I'm sure Gulfstream would be using LE devices too if they thought it would produce better results.
Last edited by Astra driver; 11th Dec 2013 at 16:50.