Engineering:IAI Westwind

Jet Commander/Westwind
The Westwind is a Business aircraft with a mid-wing and two aft-mounted engines
Role	Business jet
Manufacturer	Aero Commander Israel Aircraft Industries
First flight	27 January 1963
Introduction	1965
Status	Active service
Primary user	Pel-Air
Produced	1965–1987
Number built	442
Developed from	Aero Commander 500
Variants	IAI Astra Gulfstream G100

The IAI Westwind is a business jet initially produced by Aero Commander as the 1121 Jet Commander. Powered by twin GE CJ610 turbojets, it first flew on January 27, 1963, and received its type certification on November 4, 1964, before the first delivery. The program was bought by Israel Aircraft Industries (IAI) in 1968, which stretched it slightly into the 1123 Westwind, and then re-engined it with Garrett TFE731 turbofans into the 1124 Westwind. The 16,800–23,500 lb (7.6–10.7 t) MTOW aircraft can carry up to 8 or 10 passengers, and 442 were produced until 1987.

Development

Early 1121 Jet Commanders are powered by thin CJ610 turbojets, and they have five starboard and three or four port windows.

Later 1123 Westwinds are stretched by 22 in (56 cm), they have tip tanks, and six starboard and five port windows.

The 1124 Westwind is powered by two larger Garrett TFE731 turbofans, the Sea Scan maritime patrol aircraft of the Israeli Air Force has a nose radome and additional aerials.

The final 1124A Westwind 2 has winglets on the tip tanks

Aero Commander

The Westwind was originally designed in the United States by Aero Commander as a development of its twin-propeller namesake aircraft, first flying on January 27, 1963, as the Aero Commander 1121 Jet Commander. After successful testing, the aircraft was put into series production with deliveries to customers beginning in early 1965.

After initial testing of the prototype, it was modified to production standard with an addition of 2.5 ft to the fuselage length and increased payload and maximum weights. The second prototype first flew on April 14, 1964, which was followed by the first production aircraft in November 1964. Type approval was awarded by the FAA in November, enabling the first customer delivery on January 11, 1965.

Shortly thereafter, Aero Commander was acquired by North American Rockwell. The Jet Commander created a problem, since Rockwell already had an executive jet of its own design, the Sabreliner, and could not keep both in production because of antitrust laws. Therefore, the company decided to sell off the rights to the Jet Commander, which were purchased by IAI in 1968.

Israel Aircraft Industries

Jet Commander production amounted to 150 aircraft in the United States and Israel before IAI undertook a series of modifications to create the 1123 Westwind. These included stretching the fuselage and increasing maximum takeoff, maximum landing, and maximum zero-fuel weights, with the wing modified to incorporate double-slotted flaps and drooped leading edges and tip tanks. The trimmable horizontal stabiliser was also modified to have increased span and more travel. Not long after the aircraft went into production, the original General Electric CJ610 turbojet engines were replaced by more fuel-efficient Garrett TFE731 turbofans Numerous airframe modifications also were made, such as drooped leading edges on the wings, a dorsal fin, revised engine pylons and nacelles, and further increases in maximum takeoff, maximum landing, and maximum zero-fuel weights. With improvements to a number of onboard systems incorporated, as well, these changes resulted in the 1124 Westwind delivered from 1976.

In 1976, in the wake of the terrorist takeover of the Savoy hotel in Tel Aviv, the Israeli Air Force decided to use the Westwind as the basis for a maritime patrol aircraft, which became known as the IAI Sea Scan. It had originally been developed to meet a requirement for the United States Coast Guard to replace the Grumman HU-16 Albatross, but they selected the Dassault Falcon instead.

In 1980, deliveries of the Model 1124A commenced; modifications included a new wing centre-section and the addition of winglets to the tips. The revamped aircraft was called the Westwind II, replacing the original design in production. IAI built its last Westwind in 1987, after a total of 442 Jet Commanders and Westwinds had been built, switching production to the Astra.

By 2018, 1980s Westwind 1124s were priced from $300,000 to $700,000.

Design

The Jet Commander/Westwind was of broadly conventional business jet arrangement, with two engines mounted in nacelles carried on the rear fuselage, but the wings were mounted halfway up the fuselage instead of the typical low-wing arrangement of aircraft in this class.

At FL310 and Mach 0.74 (489 kn; 907 km/h), the 1124 burns 1,600 lb (730 kg) per hour, and 1,200 lb (540 kg) at Mach 0.7 (463 kn; 858 km/h).

Variants

Type certificate data sheet

	Model	Approved	Engines	Thrust	Mmo	Ceiling	MTOW	pax	fuel	Serials
1121	Nov 4, 1964	CJ610-1/-5	2,850–2,950 lbf 12.68–13.12 kN	0.765	40,000 ft 12,192 m	16,800–17,500 lb 7,620–7,938 kg	8	926 US gal 3,505 L	3-120
1121A	Sep 19, 1967	CJ610-1	2,850 lbf 12.68 kN		41,000 ft 12,497 m	17,500 lb 7,938 kg		1,090 US gal 4,126 L	121-131
1121B	Apr 23, 1968	CJ610-5	2,950 lbf 13.12 kN						132-150
1123	8 Dec 1971	CJ610-9	3,100 lbf 13.79 kN			20,700 lb 9,389 kg	10	1,300 US gal 4,921 l	36 built
1124	17 Mar 1976	TFE-731-3-1G	3,700 lbf 16.46 kN		45,000 ft 13,716 m	23,500 lb 10,659 kg		1,400 US gal 5,300 l
1124A	Apr 17, 1980			0.785

The 1122 Type Certificate was cancelled, the two airplanes manufactured have been converted to model 1123. The 1124N Sea Scan is a maritime surveillance aircraft, and the 1124 was renamed Westwind I after the introduction of the 1124A Westwind II. The 1121C is an unofficial designation for 1121 aircraft modified under a Supplemental Type Certificate with an increased all-up weight available from 1971. The 1123 Westwind was stretched by 22 in (56 cm).

Accidents and incidents

• The Rockwell 1121 had 21 hull-loss accidents causing 45 fatalities, and the IAI 1124 had 25 hull-loss accidents causing 47 fatalities.
• The latest, on March 29, 2020, an air ambulance operated by Lionair, caught fire and exploded during take off at Manila Airport, killing all five passengers and three crew.

Specifications (1124A Westwind II)

IAI Westwind II

Data from Jane's All The World's Aircraft 1982-83

General characteristics

• Crew: 2
• Capacity: 7 pax normal (maximum 10) / 1,474 kg (3,250 lb) maximum payload
• Length: 15.93 m (52 ft 3 in)
• Wingspan: 13.65 m (44 ft 9 in) , 13.16 m (43 ft) excluding tip tanks
• Height: 4.81 m (15 ft 9 in)
• Wing area: 28.64 m² (308.3 sq ft)
• Aspect ratio: 6.51
• Airfoil: IAI 54-12 (Sigma 1 modified)
• Empty weight: 4,536 kg (10,000 lb)
• Max takeoff weight: 10,660 kg (23,501 lb)
• Fuel capacity: 4,345 kg (9,579 lb)
• Powerplant: 2 × Honeywell TFE731-3-1G turbofan engines, 16.46 kN (3,700 lbf) thrust each

Performance

• Cruise speed: 723 km/h (449 mph, 390 kn) economical at 11,890–12,500 m (39,000–41,000 ft)
• Stall speed: 184 km/h (114 mph, 99 kn) at maximum landing weight, flaps down, engines idling
• Never exceed speed: 868 km/h (539 mph, 469 kn) at 8,840 m (29,000 ft)
• Range: 4,430 km (2,750 mi, 2,390 nmi) 10 pax, 5,385 km (3,346 mi; 2,908 nmi) with maximum fuel and four passengers
• Service ceiling: 13,725 m (45,030 ft)
• Rate of climb: 25.4 m/s (5,000 ft/min) at sea level
• Wing loading: 372 kg/m² (76 lb/sq ft)
• Thrust/weight: 0.31
  
• Take-off balanced field length: 1,600 m (5,200 ft)
• Landing run from 15 m (49 ft): 747 m (2,450 ft) at maximum landing weight

See also

• Aero Commander 500
• British Aerospace 125
• Hamburger Flugzeugbau HFB 320 Hansa Jet
• Piaggio PD.808
• Learjet 35/36
• Cessna Citation III

External links

• "Worthington Aviation LLC". http://www.worthingtonav.com/corporate.php. "the Westwind Global Support provider" 
• Mark Huber (June 2010). "Westwind II". Business Jet Traveler. https://www.bjtonline.com/business-jet-news/westwind-ii.