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-   -   Vref - Slatted v Non Slatted Wing (https://www.pprune.org/biz-jets-ag-flying-ga-etc/612797-vref-slatted-v-non-slatted-wing.html)

Guptar 30th Aug 2018 06:15

Vref - Slatted v Non Slatted Wing
 
Comparing G650 v Global of similar size

What's the typical Vref of a G650. How does that compare to the slatted wing of the Globals.

is the added complexity & weight of the slat system worth it. It seems that most largish jets are being designed with fixed leading edges.

is there any significant differences in handling qualities between the two jets in take-off and landing configuration.

josephfeatherweight 30th Aug 2018 09:11

The G650 achieves an amazingly low Vref for a non-slatted wing - certainly no more than 10 kts faster than a Global for the same weight.

Guptar 31st Aug 2018 01:08

Well, one reply. Pprune has certainly changed. 10 years ago one would ask a question and you would get a dozens or responses in a matter of hours from people who really knew their subject. Those times are long gone. No experts around here any more.

Jarema 31st Aug 2018 03:40

Hi,

Most of the time Vref on G650 is about 118kt (about 6000lbs fuel load, 6-8 pax). Vapp is +5kt and is more than sufficient. No need to add extra for wind unless its really gusty.

Klimax 31st Aug 2018 08:12


Originally Posted by Jarema (Post 10237876)
Hi,

Most of the time Vref on G650 is about 118kt (about 6000lbs fuel load, 6-8 pax). Vapp is +5kt and is more than sufficient. No need to add extra for wind unless its really gusty.

Yeah, rule of thumb you can do 110kts + payload and fuel. 6000 lbs is a comfortable arrival fuel with 118kts Vref as mentioned. Don't know about the Global, sorry.

BizJetJock 31st Aug 2018 09:44

Global 6000 at 62,000lbs landing weight Vref 114kts. That's a similar loading depending on the empty weight of your aircraft.

josephfeatherweight 31st Aug 2018 10:29

Dreadfully sorry to disappoint you, Guptar.

DCThumb 31st Aug 2018 16:47

Global take off performance, in the wet, is significantly better than a G650!

GlenQuagmire 31st Aug 2018 17:52

Ref on the Global is typically between 110 and 115. We fly ref and dont add anything unless conditions dictate.

Klimax 1st Sep 2018 21:02


Originally Posted by DCThumb (Post 10238310)
Global take off performance, in the wet, is significantly better than a G650!

Wow, that's awesome.

TheWrongTrousers 15th Sep 2018 17:08


Originally Posted by Guptar (Post 10237821)
Well, one reply. Pprune has certainly changed. 10 years ago one would ask a question and you would get a dozens or responses in a matter of hours from people who really knew their subject. Those times are long gone. No experts around here any more.

PPRUNE....experts 🤣🤣🤣🤣🤣🤣🤣 Probably because 10 years ago this site was used by professionals primarily.



DCThumb 16th Sep 2018 07:36

I’ve not flown both but have spoken to guys who have!

The 650 is nicer to fly on approach as it is much more responsive in roll - the Global can feel a bit wallowy at times!
This May be down to the slightly higher approach speeds, but much more likely to be that the Gulfstream wing is much stiffer. The Global wing is very flexible and gives a much more comfortable ride in the cruise...

If you want detailed perf comparisons, I have perf calculators for both types.

His dudeness 16th Sep 2018 08:32


Originally Posted by Guptar (Post 10237821)
Well, one reply. Pprune has certainly changed. 10 years ago one would ask a question and you would get a dozens or responses in a matter of hours from people who really knew their subject. Those times are long gone. No experts around here any more.

So you ask a specific question about 2 types that are not exactly "Volkscrafts" - not 5 of em on every airport - that would require a person to answer it correctly to have flown both and then you whine about no answer ?

His dudeness 16th Sep 2018 08:33


Originally Posted by TheWrongTrousers (Post 10249974)


PPRUNE....experts 🤣🤣🤣🤣🤣🤣🤣 Probably because 10 years ago this site was used by professionals primarily.




A 2015 joiner..?

GlenQuagmire 16th Sep 2018 20:43

Ask this question 10years ago and I suspect there would have been no answers at all because there werent a lot of G650s 10 years ago

mystere-falcon 18th Sep 2018 21:34

you should compare global vs GV-550 if you want to compare slatted vs non slatted Vref, with the FBW the 650 has probably a Vref=1.23 instead of 1.3

His dudeness 19th Sep 2018 06:18


Originally Posted by mystere-falcon (Post 10252265)
with the FBW the 650 has probably a Vref=1.23 instead of 1.3

Our C680 has a Vref of Vs * 1,23 and certainly no FBW....

Jimbo Pyne 25th Sep 2018 07:55

Aircraft with slats/leading edge devices are certified to 1.23 Vs = REF as opposed to 1.33 Vs = REF for those with just flaps, under CS-25.

That will help massively with performance figures....

As for the thewrongtrousers, I'm sure that more than one person has changed account on here at some stage! :}

His dudeness 25th Sep 2018 11:06


Originally Posted by Jimbo Pyne (Post 10257725)
Aircraft with slats/leading edge devices are certified to 1.23 Vs = REF as opposed to 1.33 Vs = REF for those with just flaps, under CS-25.

That will help massively with performance figures....

As for the thewrongtrousers, I'm sure that more than one person has changed account on here at some stage! :}

Our C680 has a Vref of Vs * 1,23 and certainly has no slats/LEDs....

Mad (Flt) Scientist 25th Sep 2018 14:35

The question of 1.23 VSr vs 1.3 Vs for the minimum speed for Vref depends on the amendment standard of the rules at the time of applying for cert, plus any issue papers that may have shown up. It's got nothing to do, as has been stated, with any specific design feature (slats, FBW, whatever)

Note that this is only ONE of several minimum criteria for Vref. It doesn't always follow that Vref is set at this specific minimum


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