A slew of improvements await your Learjet or King Air
James D. Raisbeck abhors the term modifier. Instead, he insists that the various products Raisbeck Engineering sells for Beech King Airs and Learjets are systems, not merely modifications to the airplanes. In the Raisbeck world, companies that make extensive modifications to airplanes may be hurting more than they help, particularly if they're unlucky enough to go out of business and leave the hapless owner with a hard-to-support hybrid. And while parsing the differences in the two terms — modifications versus systems — may represent more an exercise in semantics, there's no denying that Raisbeck is a major player among the turbine set.
The company has become so without radical redesigns or gobs of extra-production thrust; instead, Raisbeck has aimed its resources at improving details. Aerodynamic devices intended to reduce drag and improve stability are among the Raisbeck hallmarks, as are alterations that increase utility. Perhaps the most telling characteristic of the Raisbeck family of modification is that the vast majority of them can be easily — though not necessarily inexpensively — decommissioned.
An aeronautical engineer (with a degree from Purdue University) who started his career at Boeing and honed it as chief engineer for Robertson Aircraft in the early 1970s, Raisbeck founded his own company in 1973. Early work on wing alterations for the 20- and 30-series Learjets and the Model 60, 65, and 80 Sabreliners led eventually to the company's emphasis on the Beech King Air line. Raisbeck knows a fertile market when he sees one; Beech's venerable turboprop provides a whopping large fleet of airplanes that haven't been changed radically in more than 30 years.
Today, the company's big news is a baggage locker for the 30-series Learjets. The composite aft body mates seamlessly to the underside of the Learjet tailcone. Its shape is intended to improve airflow in the wing's downwash, allowing the air to rejoin more smoothly and to help prevent the formation of drag-producing vortices. Moreover, the baggage bay presents greater vertical or tail area, giving the airplane the benefit of additional ventral-fin effect.
Inside the bay, Raisbeck says, there's room for seven sets of snow skis or as much as 300 pounds of baggage. You gain access to the bay by opening two latches on the left side of the compartment and pulling another handle mounted further aft (looking suspiciously automotive). The bay then slides toward you; a composite lid is secured by two latches. It's easy to load items into the waist-high bay.
How well does the baggage bay work, aerodynamically? A crew assigned to a Raisbeck-modified Lear 35 said that they experienced a 7-percent reduction in fuel flows at normal cruise speeds. Moreover, low-speed handling was improved and Dutch-roll characteristics reduced, even with the yaw dampers off. Finally, the crew tried a water-bottle test to see if items in the bay would freeze, but they had little success. The bay is not pressurized, however. It lists for $67,450 and adds 50 to 80 pounds. Budget for 150 hours of labor for installation.
Though Raisbeck is aggressively marketing the Learjet mod, the company made its name in the King Air world, and it's fair to say that it has been fantastically successful there. According to the company, it has 50-percent penetration in the 200/B200 King Airs and more than 30 percent into the entire King Air fleet.
At the core of Raisbeck's King Air packages are aerodynamic tweaks to the long-lived turboprop. First on the list are Raisbeck-specified Hartzell four-blade aluminum propellers, called Quiet Turbofan Propellers. Claiming improved thrust and efficiency, Raisbeck says that your typical King Air will be able to cruise at lower prop rpm for a much quieter cabin and less airframe vibration. If you are flying a King Air Model 200, you can gain some speed and climb performance with Raisbeck's ram air recovery system, dubbed RARS. By changing the inlet-air path to the PT6A, this system offers a claimed 8-percent increase in available horsepower or a 20-degree-F-cooler ITT at a given torque setting. Raisbeck has performed its magic by simply cleaning up the aerodynamics of the intake path and by inserting a turning vane near the back of the duct; this addition helps the incoming air to make the turn to the PT6A's rear inlet more efficiently. In addition, the RARS is said to suffer little performance penalty with the PT6A's ice vanes deployed.
Other aerodynamic tweaks take place outside the King Air. Raisbeck makes recontoured leading edges for the inboard wing sections on the King Air 200 models. This alteration supposedly improves the airflow over the wing between the fuselage and the engine nacelle, providing better overall lift distribution and, because the inboard sections provide more of the total lift, improved outer wing panel life. Moreover, Raisbeck says that the leading edge change will increase cruise speed and improve low-speed handling. A revised ducting system for the in-wing intercooler is said to increase the air conditioner's efficiency.
If you operate an F90, 100-series, or 200-series King Air with the larger high-flotation main gear tires, Raisbeck can supply fully enclosing gear doors. (In the stock big-wheel option, the tires protrude from the truncated gear doors.) Raisbeck says that the doors increase cruise speed at higher altitudes by 8 to 15 knots.
Further aerodynamic tweaks include Raisbeck's dual aft body strakes. These trapezoidal panels help to improve the airflow around the lower empennage, particularly in organizing the turbulent downwash from the wing. As a result, Raisbeck says, all models will see reduced minimum-controllable speeds (VMCa) and better directional stability. In some King Air models, the yaw-damper limits have been eliminated or raised.
Raisbeck makes a line of "systems" for the entire King Air line, and this includes nacelle wing lockers — certified to carry 600 pounds of cargo — that are claimed to be removable in 5 minutes for maintenance purposes. These composite lockers graft on so cleanly to the backs of the stock nacelles that they look as though they've been there (or should have been) from the start. Even more clever are the exhaust stack fairings. Owners of PT6A-powered airplanes know the soot dilemma well; exhaust gases travel back from the stacks and swirl with the prop slipstream, coating the nacelles and wings with swirling, smudgy streaks. Raisbeck's fairings trip the boundary layer between the local exhaust slipstream and the nacelle, keeping the soot from attaching as quickly.
Many of these components can be purchased separately, but Raisbeck does the majority of its business in packages. For example, a B200 King Air modified with the new props, ram-air recovery system, revised leading edges, dual aft body strakes, and fully enclosed high-flotation gear would have undergone a $94,950 retrofit, excluding the approximately 265 hours for the installation.
James Raisbeck is understandably proud of the entire product line, but he is quick to point out that there's more beneath the surface. For example, each of the systems kits comes with a revised aircraft flight manual. While most modifiers do not adjust the book numbers, usually claiming no degradation of standard performance, Raisbeck has taken the time to flight test and document all forms of performance with the grouped modifications. In this way, crews of Raisbeck-equipped airplanes need never to guess at the expected performance. It may be this last step — an indication of attention to detail — that separates Raisbeck's systems from those of mere modifiers.
For more information, contact Raisbeck Engineering, Inc., 4411 South Ryan Way, Seattle, Washington 98178; telephone 800/537-7277 or 206/723-2000; fax 206/723-2884.
