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Improving business aircraft performance

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Customized installations such as cockpit upgrades and improved engines lower fuel consumption and enhance performance.


By Shannon Forrest
President, Turbine Mentor
ATP/CFII. Challenger 604/605, Gulfstream IV, MU2B

An Air France Concorde is permanently on exhibit inside the Udvar-Hazy Center at IAD (Washington–Dulles VA). Its sleek fuselage, massive engines, and delta wing always draw a crowd. On February 7, 1996, a Concorde operated by British Airways set the record for the fastest commercial transatlantic flight between New York and London, covering 3259 nm in 2 hours, 52 minutes, and 59 seconds – a record that still holds today.

There’s a relatively undistinguished turboprop (TP) near the Air France Concorde at the Udvar-Hazy. The official museum designation is “Beechcraft 65-90,” but anyone with a knowledge of business aircraft would recognize it as a King Air.

604XT
Nextant 604XT

When compared to the adjacent Concorde, the King Air may seem mundane to the non-flying public. However, this aircraft marked a turning point in the history of business aviation.

Technically, the aircraft on display is designated as both a Queen Air and a King Air.

The Queen Air was designed by Beechcraft as a compromise between the Bonanza and the Model 18. Eventually, Beech replaced the reciprocating Lycoming powerplants on a Queen Air with Pratt & Whitney Canada (P&WC) PT6 turboprops, and renamed it the King Air.

To this day, the King Air is the most popular TP ever manufactured. Passengers love the roomy interior, and pilots appreciate the subtle and predictable flying characteristics.

The product line runs the gamut from entry-level to long-range examples equipped for special missions.

Nextant offers its 604XT with a redesigned passenger cabin, engines with improved performance, and Collins Aerospace Pro Line Fusion avionics with synthetic and enhanced vision systems as standard features. Optional features include graphical weather and TCAS 7.1.

This TP has always been a conundrum for flight departments, as it’s faster than an aircraft with a reciprocating engine (and statistically safer with the seemingly bulletproof PT6), although not as fast as a jet. It’s also easy to fly, with an impeccable safety record.

TPs vs jet aircraft

One question that always comes up when comparing TPs to jets is whether the speed associated with a jet justifies the additional costs.

Without a doubt, TPs are cheaper to operate, and pilot training costs are lower. This is especially important given the current dearth of pilots.

In the case of the Beech King Air, the fact that the aircraft has more aftermarket modifications available than any other production aircraft makes a compelling argument that the TP is a better deal for owners/operators.

Performance enhancements allow the aircraft to close the TP/jet speed gap, without a large appreciable increase in price.

The reason the King Air is the target of so many upgrades outside of the OEM channels is economics. There are a lot of reasons, and reputation also plays a role.

To borrow a phrase from the homebuilding industry, the aircraft has “good bones.” Owners can appreciate that it’s always more economical to retrofit an aircraft than it is to replace it with the latest model rolling off the assembly line. A brand new King Air may cost more than $8.5 million.

King Air
King Air 350

Aftermarket manufacturers are not constrained by the requirement to certify the entire aircraft and all its systems, nor do they need to operate under the business philosophy of appealing to a wide audience of consumers.

Instead, they can focus their engineering expertise on enhancements that solve specific problems or achieve gains in distinct areas.

This means that an operator can improve performance or comfort parameters that are important to their mission without having to make tradeoffs or compromises.

Record-breaking TPs

A seemingly unremarkable aircraft such as the King Air sitting near the Concorde at the Udvar-Hazy Center can also be a record holder. A modern iteration of it – a King Air 350 – clocked an official speed record between GEG (Intl, Spokane WA) and ORL (Exec, Orlando FL) on October 16, 2022.

The aircraft left GEG at 1:39 pm PDT and arrived in ORL at 12:25 am EDT. After adjusting the calculations to correct for crossing time zones, the result was a point-to-point flight time of 7 hours and 46 minutes.

King Airs are a main target of aircraft mods because there are a great many in operation and they offer a solid platform for add-ons. Pictured are a King Air 350 and a P&WC PT6 turboprop engine.

At first glance, it doesn’t garner the excitement of crossing the Atlantic at Mach 2 while sipping champagne and eating caviar. The highest altitude the flight attained was FL350. However, a savvy King Air pilot might recognize the nuance here – the flight was completed nonstop and landed with IFR reserves.

The milestone is endurance rather than speed, and it was achieved in a novel way. Historically, the only way to accomplish an endurance feat of this magnitude would be to increase fuel capacity. In this instance, the key was changing the aerodynamics.

Tamarack Aerospace, headquartered in Sandpoint ID, holds more than 30 aviation-related patents. One of the most exciting is the ATLAS load alleviation technology and active winglet. The invention is the brainchild of Nick Guido, a seasoned engineer and entrepreneur.

Tamarack employs a 3-phase solution to improving performance. In addition to composite winglets, Tamarack adds a lightweight composite wing extension and load alleviation system. The “secret sauce” underpinning the system is that the load alleviation system responds to changing flight conditions and can alter the performance of the winglet.

Tamarack describes the process as “turning off” the winglet in certain circumstances. This feature is a substantial improvement from a traditional winglet, which maintains the same characteristics irrespective of flight conditions. Tamarack’s technology has fundamentally changed the winglet from passive to active.

Using the system on the King Air is a relatively recent decision, although the idea has been around since 2015, when Tamarack installed the first set on a Citation CJ1. Today, more than 150 jets have the modification.

CJI
Citation CJI

Aside from the obvious benefits of reduced fuel consumption, there are important safety aspects at play here. A common scenario is improving performance on hot-and-high takeoffs, but a recent discussion with company founder and inventor Nick Guido, who is also a pilot, highlighted additional important risk mitigation elements of the modification.

Lower approach speeds associated with the installation increase stability and, at the same time, reduce the chances of a runway overrun on landing.

One of the worst-case scenarios a pilot can experience is an engine failure on takeoff. When deciding between a TP and a jet, how the aircraft performs on a single-engine climb can be an obstacle in the buying process. The Tamarack system significantly improves single-engine performance.

The Smartwing is not yet commercially available for the King Air, but Tamarack expects approval soon.

Tamarack’s Smartwing has been in operation on Citation CJ1 twinjets since 2015. The company has tested the system on a King Air 350 and expects approval soon for turboprop operations.

In addition, the company is so confident in the performance gains associated with the technology that it intends to pursue relationships with commercial airlines that have fleets equipped with traditional passive winglets.

Popular upgrades

When searching for a used King Air, one is hard pressed to find one that hasn’t had at least one aftermarket upgrade. One of the most popular mods is the Crown Wing Locker System (CWLS) made by Raisbeck Engineering.

Bulky or odd-shaped baggage, such as golf clubs and skis, has always been a challenge. In the past, the solution was to lay them down between passenger seats in the cabin, which was not an elegant solution.

The CWLS, which is installed in the nacelle, adds 17 cu ft or 600 lb of luggage space. The locker is exterior to the cabin, but interior to the primary structure, so the installation won’t add drag.

Raisbeck’s Dual Aft Body Strakes modification is popular as well. It replaces the factory-installed ventral fin, resulting in reduced drag and improved directional stability during all phases of flight.

A key advantage of the retrofit is that the Dual Aft Body Strakes remove or increase the altitude limitation associated with the yaw dampener being inoperative, which means greater dispatch reliability.

Raisbeck Engineering’s Crown Wing Locker System (CWLS) adds 17 cu ft of luggage space (or 600 lb).

Although Raisbeck offers at least one upgrade for each model within the King Air product line, the 200 seems the most operationally ubiquitous, and, therefore, has more options.

A Ram Air Recovery System (RARS) – developed in conjunction with Pratt and Whitney – takes advantage of Coanda effect aerodynamics to achieve efficient airflow vectoring to the powerplant.

The company claims that benefits include an 8% increase in available horsepower, decrease in fuel flow at equal engine torque, reduced torque loss with ice vanes deployed, and cooler operating ITT of 18º C.

Enhanced Performance Leading Edges (EPLE) replace the factory leading edges with lower-weight composite construction to improve stall speeds and increase range and cruise speed. Retrofitting OEM propellers can improve acceleration and decrease stopping distance.

The composite 5-blade 96-inch diameter prop (for the 200 series) weighs 48 lb less than the OEM propeller, reduces noise by 30%, and achieves a 16.5% gain in runway acceleration.

Modifying aircraft engines

The status quo for aircraft powerplants has always been the factory. Approximately 2 decades ago, specialized engine shops began to spring up that offered customized installations or significantly modified stock powerplants. It began with pistons, but now extends to TPs and jets.

Blackhawk Aerospace in Waco TX describes its purpose as “to increase TP aircraft performance, speed, usability, and reliability without the cost of buying new.” Blackhawk offers upgrades for nearly all King Air models, with 3 options available for the King Air 200 alone. It’s a matter of how fast and high you want to go. Or, framed another way, how much you want to spend.

The gist is that Blackhawk takes a core P&WC PT6 engine from an operator and replaces it with a higher-
performing variant of the same engine. The top-of-the-line upgrade for the 200 is the XP52, which boasts a 25% increase in climb rate, 31% more horsepower, and is expected to deliver full torque to FL260.

Dual aft body strakes reduce drag and improve directional stability during all phases of flight.

Pilots are expected to see true airspeeds around 311 kts. The mid-level upgrade is the XP61, which advertises a 17% increased climb rate and a speed of 305 kts in cruise. Aside from the obvious safety benefits, Blackhawk points out that having one of its engines achieves a return on investment at resale time.

Refreshing business aircraft

Remanufacturing and/or modifying existing aircraft can be a significant cost advantage over buying new, especially during times of high inflation. Nextant Aerospace offers its G90XT – a completely remanufactured Beech King Air C90A that’s been fitted with modern amenities and avionics.

The G90XT comes equipped with a General Electric (GE) H75 powerplant that delivers cruise speeds of up to 280 kts.

The TP engine is controlled by a single-lever actuator – a first for TPs – and an electronic engine control system. The Regent flight deck comes with a Garmin G1000 package, complete with 3 LCD screens and an integrated GFC700 autopilot.

Other company conversions include the 400XTi, based on a Beechjet, and the 604XT. Both aircraft are refreshed with Collins Aerospace avionics and engines with improved performance, and buyers have the option to either refurbish or redesign the aft cabin interior.

Purchasing a new aircraft is a big financial decision which may be an easy choice for the “cost is no object” crowd. For the rest of the buyers out there, there’s a myriad of choices to enhance their aircraft in terms of aesthetics, comfort, and performance. With the right refurbishments, an operator can achieve equal-to or better-than-new performance at a much lower price.


ForrestShannon Forrest is a current line pilot, CRM facilitator, and aviation safety consultant. He has more than 10,000 hrs TT and holds a degree in behavioral psychology.