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Home | Update | Latest Issue | Gallery | FR Profile | Datafiles | FR 12/97 LEARJET 45 IS CERTIFIED by Norbert Burgner With a nine-month delay, the youngest member of the Lear family, the Model 45, received its FAA certification at the end of September. Mid-size jet comfort for light jet costs. This was the goal when the Learjet 45 was announced in 1992. The aircraft was to catapult the traditional manufacturer back to the top of the business jet market within five years, ex-Lear head Brian Barents said at the occasion of the roll-out in September of 1995. Back then, the first flight of the new Lear was scheduled for the third quarter 1995 and the certification for the end of 1996. In 1997, the first 36 units were supposed to roll off the line. For 1998, there were 48 aircraft planned and in 1999, even 60 new Lears were supposed to leave the plant in Wichita, Kansas. The new Lear really flew for the first time on 7 October, 1995. However, what followed is, with 2023 flight hours in 1079 flights, certainly one of the most extensive certification programs in the history of aviation but, because of this as well a major disappointment for the company and its mother Bombardier. The facts are known: Some major mistakes were made before the development started. For example, it went unnoticed that the design software used by the three participating Bombardier subsidiaries, de Havilland, Shorts, and Learjet, were not compatible. This lead to flaws in the design of the wings and the landing gear. In short: the work was bad. Consequences followed: Learjet monarch Barents had to go and almost the entire management and production were replaced. "Reaction forces" were sent from Bombardier headquarters in Montreal to Wichita with the task to save what could be saved. While the result has a somewhat damaged history (out of above reasons), the new Lear doesn't have to hide at all. In its aerodynamical basis, which was designed with the help of a special software (Tranair), developed by Boeing and NASA, the Lear 45 is featuring a 14 percent larger fuselage as compared to the smaller model 31A. In combination with the new wings, the aircraft generates approximately 34 percent more lift and 14 percent less drag at a cruise speed of Mach 0.8. The 45's wing is the result of intensive computer based flow diagnostics. The wing is swept by 13,4 degrees and, with its supercritical profile, is able to generate high cruise speeds as well as good slow speed characteristics. The supercritical winglets, also designed by NASA, are designed to control the wingtip vortices, such improving the climb and cruise performance. The U-shaped connecting section of the two wings runs underneath the cabin and not through it, resulting in an even floor all the way through the cabin. The wing leading edge is slightly dropped over three quarters of the wing span. This design was the result from the requirement of getting low stall speeds and good handling characteristics along with maintaining the high-speed performance. A total of four Vortilons are installed on the underneath side of the wings, additionally improving the stall characteristics. The small wing fences are working against undesired airflow over the wingspan at high angles of attack. The cabin of the Lear 45, with a length of six meters, is 80 centimeters longer than the passenger room of the preceding models (35A and 36), which the new model is designed to replace. With a width of 1,55 meters and a height of 1,50 meters, the cabin is also offering more freedom in the head and shoulder area. The fuel capacity, which was increased from the originally projected 6000 lbs to 6054 lbs (3432 liters), in combination with a better fuel economy, increased the range of the new Lear from 2200 nm (4074 km) to 2380 nm (4407 km). However, this number is for operation under visual flight rules. During normal flight ops under IFR, with two-man crew and four passengers, and a fuel consumption of 605,7 liters per hour, the tanks hold enough fuel to cover a range of 3704 km. The necessary kerosene is carried in one fuselage tank and the two wings. Independent from the larger fuel capacity, the weight of the Lear 45 increased by another 650 lbs (294 kg) due to structural changes on wings and landing gear, resulting in a maximum take-off mass of 20200 lbs (9163 kg). According to Bombardier, this weight increase does not affect the flight performance. As compared to the AlliedSignal turbofans of the preceding Lear models, the 45's new TFE731-20s give an 11-percent improvement in specific fuel consumption, at the same time delivering 15 percent more thrust. Up to an outside temperature of 31 degree centigrade, the engines generate 15,56 kN (3500 lbs) take-off thrust each. This allows the eight-seater a high-speed cruise of Mach 0.81 (858 km/h). The normal cruise speed of the new Lear is given to be Mach 0.77 (817 km/h). The Lear 45 suffered somewhat in its short-field performance. The twin-jet now needs a 170 meter longer take-off distance (1451 meters) and a 45 meter longer landing distance (957 meters). All together, the performance of the Lear is sufficient to cope with the competition at any time, says Michael Graff, president Bombardier business aircraft: As compared to competitors such as the Cessna Citation V or the Beechjet 400A, the 45 offers its operator a range of up to 1031 km longer. Even in comparison to the significantly larger Citation VII, the new product from Learjet supposedly has a range advantage of 506 km (VFR). Concerning the cabin volume, the new Lear is exceeding the competitors by up to 30 percent. The mid-size category Citation VII, with 11,93 cubic meters cabin volume, supposedly offers only little more space than the Lear 45 (11,48 cubic meters). As the actual rival, the Learjet marketing experts have identified the new Citation Excel. However, Bombardier says that while the shortened cabin of the Citation X in combination with the wings and empenage of the Citation V Ultra would give the Excel (certification is scheduled for the beginning of next year) a 700 kg lower take-off mass than the new Lear but, still has the same operating costs. Assuming an average sector of 600 nm (1111 km), the new Lear supposedly covers this flight with an average speed of 371 kts (687 km/h), using approximately 605 liters of fuel per hour. The Excel would only fly at a speed of 353 kts (653 km/h), at the same time using approximately 20 percent more fuel (718 liters per hour) than the Lear. Accounted to in operating costs, the Excel (fuel price per liter 0,52 dollars) would generate operating costs of 380 dollars per hour as compared to 320 dollars for the Lear 45. Furthermore, adding the necessary expenses for maintenance and repair (work-man-hours 1,6 = 92,63 dollars as compared to 108,30 dollars, parts costs 52,73 dollars as compared to 150,65 dollars, accumulating costs for engine maintenance 188,20 dollars as compared to 202,10 dollars, check of the thrust reversers eight dollar both aircraft, additional work also 40 dollars for both of the competitors) one ends up with hourly operating costs of 701,56 dollars for the Lear 45 and 889,05 dollars for the Excel, resulting in 20 percent ($187,48) lower costs for the Learjet operator. Experts from Lear mother Bombardier have calculated for an entire flight that the Lear operator will have to spend approximately one dollar per kilometer while the Excel operator will face 1,36 dollars per kilometer (36 percent more). Cessna will certainly be able to present its own numbers for the comparison, as proven by approximately 200 entries in the order log for the Excel. Still, even Bombardier could be pleased with the customer interest for the first new aircraft of the manufacturer since long. With approximately 135 fixed orders before the aircraft was certified, the "Model 45" is the most successful Lear yet. From page 26 of FLUG REVUE 12/97 Home | Update | Latest Issue | Gallery | FR Profile | Datafiles | FR 12/97 Copyright 1997 by Motor-Presse Stuttgart. All rights reserved. Last updated November 7, 1997 FLUG REVUE, Ubierstr. 83, 53173 Bonn, Germany