Grumman Gulfstream II

The Gulfstream II (G-II) is an American twin engine business jet designed and built by Grumman and then in succession, Grumman American and finally Gulfstream American.

Its Grumman model number is G-1159 and its US military designation is C-11A.

It has been succeeded by the Gulfstream III.

The first Gulfstream II flew on October 2, 1966.

The Gulfstream II is a twinjet swept wing corporate transport powered by two Rolls-Royce Spey turbofan engines and designed to provide high speed and long-range capability without sacrificing the airport performance, reliability, and other operational advantages of its predecessor, the turboprop Gulfstream I.

Preliminary design of the wing was influenced by both cruise and low speed considerations.

The aft-mounted engine location was selected after extensive analysis and design iterations considering aerodynamic, structural, and ground clearance requirements.

Airfoil geometry was developed to maximum sweep benefit from the selected planform.

The interference problem at the wing-body juncture was treated by modification of the airfoil shape and thickness over the inner third of the wingspan.

The basic airfoils for the main area of the wing are similar to those of the Grumman A-6 Intruder aircraft and utilize NACA 6-series thickness distributions combined with an in-house mean line.

A buffet boundary commensurate with the M=.85 speed capability was attained by incorporating a row of co-rotating vortex generators on the outer wing panel.

In developing the wing contours, attention was paid to the aircraft’s low speed requirements by tailoring the leading-edge radius to preclude leading edge separation.

The high lift configuration consists of a one piece, single-slotted Fowler flap of 30% chord.

Stall initiation on the basic wing was found to occur at midspan but spread rapidly to the tip, particularly at large flap deflections.

The addition of an upper surface fence at about midspan provided a strong pitch down at the stall, without sacrificing maximum lift, and also afforded an adequate margin between initial and tip stall.

The high angle of attack investigations on the Gulfstream II indicated that stable trim conditions existed up to 45 degrees angle of attack.

The elevator deflection required to trim to the primary stall at most forward centre of gravity was sufficient to trim a deep stall at the aft centre of gravity, but recovery from deep stall was immediate upon forward stick motion, and more than adequate nose-down elevator control was available.

The acceptability of the Gulfstream II high angle of attack characteristics and the absence of a deep stall influence on configuration sizing and arrangement was attributed to the mitigating influence of the nacelle-wing overlap on nacelle contribution.

Configuration build-up studies revealed the adverse nacelle influence on tail pitching moment contribution above 30 degrees angle of attack was not unduly severe and no appreciable effect on elevator or stabilizer effectiveness was found.

It was found in flight testing that the stall characteristics were satisfactory but did not preclude stall penetrations to the point of secondary stall pitch up.

Rather than pursue a lengthy flight test research effort, and in view of the excellent primary stall behaviour, it was decided to mechanically limit the extent of stall penetration with a stick shaker and stick pusher.

During installation of the Aviation Partners Inc. winglets (as the G-IISP), the vortex generators and midspan fence were removed and replaced with six leading edge vortilons similar to those found on the Gulfstream IV.

Variants

Its Grumman model number is G-1159 and its US military designation is C-11A. 

Specifications

Crew

2

Capacity

19 / 2,900 lb (1,315 kg) maximum payload

Length

79 ft 11 in (24.36 m)

Wingspan

77 ft 10 in (23.72 m)

Height

24 ft 6 in (7.47 m)

Wing area

934.6 sq ft (86.83 m²)

Airfoil

Stn.50

NACA 0012 modified.

Stn 145

NACA 63A-009.5.

Stn 385

NACA 64 series modified

Empty weight

39,100 lb (17,735 kg)

Maximum zero-fuel weight

42,000 lb (19,051 kg)

Gross weight

65,500 lb (29,710 kg)

Max take-off weight

68,200 lb (30,935 kg)

Maximum landing weight

58,500 lb (26,535 kg)

Fuel capacity

28,300 lb (12,837 kg) maximum

Powerplant

2 × Rolls-Royce Spey 511-8 turbofan engines,

11,400 lbf (51 kN) thrust each

Performance

Stall speed

105 kn (121 mph, 194 km/h) at MLW, flaps down

Maximum cruising Mach number

M0.85 at max power at 30,000 ft (9,144 m) and AUW of 55,000 lb (24,948 kg)

Max speed

M0.85

Economical cruise speed

M0.77

Range

3,550 nmi (4,090 mi, 6,570 km) with 8 passengers, NBAA IFR reserves, crew of 3, 2,000 lb (907 kg) / pax

3,970 nmi (4,569 mi; 7,352 km) with NBAA VFR reserves

Service ceiling

45,000 ft (14,000 m)

Rate of climb

3,800 ft/min (19 m/s)

1,200 ft/min (6.10 m/s) on one engine

Take-off run (FAA)

5,850 ft (1,783 m)

Landing run (FAA)

3,400 ft (1,036 m)

Take-off

91 EPNdB

Approach

97 EPNdB

Sideline

103 EPNdB.