PPRuNe Forums - Cruise Mach for various Business Jets

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All, thanks for replies so far, very useful. Just wondered if there are any G650 pilots who would be willing to add to the discussion?

I fly the G650.
The MMO is .925. Normal cruise is .90 with long range cruise between .85 and .87.
For flights under 5000nm we will normally plan .89 as this seems to be far more fuel efficient than pushing up the power to .90.
For legs over 5000nm we will normally plan at .85 or .87 mach. Speeds below .85 do not benefit much due to the drag curve.

DA2000

MMO-.865
Intermediate- .75
LRC- dependent on temp/ ALT. In the ball park of .72
Normal cruise .80, seems to be the best of both worlds. (Speed/Efficiency)

HS-125 (800XP)

MMO- .80
Normal cruise- .74-76
LRC- .72

And for 700 series, you are lucky for .70 on a good day!

HS 125 Hawker XP series:

MMO .80

Long range .70
Normal cruise speed .76

@ FL410

Quote:

I spent 13 years in the IAI 1125 ASTRA and it was a 0.78 cruiser with 0.835 MMO. Is the SPx different?

Absolutely. It's a completely different bird.

From the QRH, max cruise:

FL450, ISA, 17000 lbs, 0.81, ISA - 10 gives 0.835, ISA + 10 gives 0.717
FL370, ISA, 24000 lbs, 0.825
FL390, ISA, 16000 lbs, 0.839
FL410, ISA, 18000 lbs, 0.83, ISA - 10 gives 0.847

Mmo 0.875
Vmo 353 KTS
High speed climb is 0.72

Lear 60,
MMo M.81 (up to F380-390)

Normal cruise .77-.78 (@F400/410)
Long range .72

Here's one: Cessna C525 CitationJet ("CJ0" as we like to call it) - M0.62 :}

The G650 is pretty impressive.

Just wondered why Gulfstream didn't give it slats and / or more range ?

GLEX - normally cruising 0,83- 0,85
LR cruise - 0,80-0,83

welle

Quote:

That change is also at 8000ft (something to do with windshield certification) - I think every Citation has it....

Bird strike protection.

Quote:

§25.631 Bird strike damage.

FAA
The empennage structure must be designed to assure capability of continued safe flight and landing of the airplane after impact with an 8-pound bird when the velocity of the airplane (relative to the bird along the airplane's flight path) is equal to VC at sea level, selected under §25.335(a). Compliance with this section by provision of redundant structure and protected location of control system elements or protective devices such as splitter plates or energy absorbing material is acceptable. Where compliance is shown by analysis, tests, or both, use of data on airplanes having similar structural design is acceptable.

EASA
The aeroplane (all structure, including windshield) must be designed to assure capability of continued safe flight and landing of the aeroplane after impact with a 4 lb bird when the velocity of the aeroplane (relative to the bird along the aeroplane’s flightpath) is equal to VC at sea-level or 0.85 VC at 2438 m (8000 ft), whichever is the more critical. Compliance may be shown by analysis only when based on tests carried out on sufficiently representative structures of similar design. (See AMC 25.631.)