Learjet_28 Knowpia

Learjet 28/29
Role	Business jet
Manufacturer	Learjet
First flight	August 24, 1977
Status	Retired
Produced	1977–1982
Number built	9
Developed from	Learjet 25
Developed into	Learjet 31

The Learjet 28 is an American eight-to-ten-seat (two crew and six to eight passengers), twin-engine, high-speed business jet, intended to be the successor to the Learjet 25. The Learjet 29 is identical except for the addition of a long-range fuel tank, resulting in the reduction of the capacity to six (two crew and four passengers). Both were manufactured by Learjet and were marketed under the Longhorn name.^[1]

History edit

The first flight of the Learjet 28 took place on August 24, 1977.^[2] The Learjet 28/29 was based on the Learjet 25, and received a completely new wing fitted with winglets which resulted in improved performance and fuel economy.^[1] The new wing was designed for the Learjet 55, and the Learjet 28 was originally planned to be a testbed for the wing, not a production type, but after the prototypes demonstrated excellent climb performance and the ability to operate at 51,000 ft (16,000 m) (the first business jet to do so), it was decided to offer the Learjet 28 and 29 as production aircraft.^[3] FAA certification was awarded to both the Learjet 28 and 29 on January 30, 1979.^[4]^[3]

The Learjet 28/29 was the first production jet aircraft to utilize winglets^[5] (entering service in 1977).

Both models were commercially unsuccessful, showing reduced range compared to the Learjet 31, as the addition of winglets required the deletion of the earlier model's wingtip tanks, and they sold mainly to customers with a requirement for good altitude performance.^[3] Only five production Learjet 28s, and four Learjet 29s, were constructed before production ceased in August 1982.^[6] Both types were subsequently replaced by the Learjet 31.

The first production aircraft was used by Neil Armstrong to set five aerospace records.^[7]

Noise compliance edit

In 2013, the FAA modified 14 CFR part 91 rules to prohibit the operation of jets weighing 75,000 pounds or less that are not stage 3 noise compliant after December 31, 2015. The Learjet 28 is listed explicitly in Federal Register 78 FR 39576. Any Learjet 28s that have not been modified by installing Stage 3 noise compliant engines or have not had "hushkits" installed for non-compliant engines will not be permitted to fly in the contiguous 48 states after December 31, 2015. 14 CFR §91.883 Special flight authorizations for jet airplanes weighing 75,000 pounds or less – lists special flight authorizations that may be granted for operation after December 31, 2015.

Specifications (Learjet 28) edit

Data from Jane's Civil and Military Aircraft Upgrades 1994–95^[4]

General characteristics

Crew: 2
Capacity: 8 passengers
Length: 47 ft 7 in (14.51 m)
Wingspan: 43 ft 10 in (13.35 m)
Height: 12 ft 3 in (3.73 m)
Wing area: 264.5 sq ft (24.57 m²)
Empty weight: 8,267 lb (3,750 kg)
Gross weight: 15,000 lb (6,804 kg)
Powerplant: 2 × General Electric CJ-610-8A turbojet, 2,950 lbf (13.1 kN) thrust each

Performance

Maximum speed: 549 mph (884 km/h, 477 kn) at 25,000 ft (7,620 m)
Cruise speed: 470 mph (760 km/h, 410 kn) ,econ cruise at 51,000 ft (15,545 m)
Stall speed: 103 mph (165 km/h, 89 kn)
Range: 1,309 mi (2,107 km, 1,137 nmi)
Service ceiling: 51,000 ft (16,000 m)

References edit

Notes

^ ^a ^b A history of the LJ23-LJ29 series on Airliners.net
^ "Learjet company timeline". Archived from the original on 2006-12-31. Retrieved 2007-01-08.
^ ^a ^b ^c Griffiths Air-Britain Aviation World Autumn 2022, p. 189.
^ ^a ^b Michell 1994, pp. 317–318.
^ Reynolds's The Learjet “Longhorn” Series—The First Jets With Winglets
^ Taylor 1982, p. 367
^ Richardson, Joshua (5 August 2020). "Historic Learjet donated to Armstrong Air & Space Museum". Dayton 24/7 Now. Retrieved 7 August 2020.

Bibliography

Griffiths, Andrew (Autumn 2022). "Learjet – The End of an Era: Part 2: Wingletted Wonders". Air-Britain Aviation World. pp. 189–193. ISSN 1742-996X.
Michell, Simon, ed. (1994). Jane's Civil and Military Aircraft Upgrades 1994–95. Coulsdon, UK: Jane's Information Group. ISBN 0-7106-1208-7.
Taylor, John W. R., ed. (1982). Jane's All the World's Aircraft 1982–83. London: Jane's Yearbooks. ISBN 0-7106-0748-2.
Reynolds, Peter T. (1979). "The Learjet "Longhorn" Series—The First Jets With Winglets". SAE Technical Paper 790581. SAE Technical Paper Series. 1. Jane's Yearbooks. doi:10.4271/790581.