Out of the ashes of the Hawker 4000 as well as drawing from its all-new Citation Latitude, Textron Aviation is creating a super-midsize jet with what could be a bright future. And thanks to that approach, the new $23.9 million Cessna Citation Longitude has comparatively few development risks, quite unlike the ill-fated Hawker that two decades ago pushed the technology envelope too far with its composite fuselage and complex systems.

Cessna engineers are capitalizing on their time-proven practice of adapting components and technologies from existing models to create additions and improved aircraft to their product offerings. For the first time, though, they’re able to use the best bits and pieces from both Citation and Hawker lines, now that former archrival Beechcraft Corp. has joined Cessna as part of Textron Aviation.

Company officials are playing down any direct link between the Hawker and Longitude, but the wings and empennages of the two aircraft bear uncanny similarities. The Longitude’s wingspan is more than 5 ft. longer, however, mostly because modestly sized winglets have been added. The Longitude’s fuselage also is almost 4 ft. longer, so aerodynamic stability should be as good, or better.

More significantly, the Longitude has a conventional aluminum monocoque fuselage that’s adapted from the Latitude. Further, the Latitude fuselage has been stretched and reinforced to accommodate another row of seats in the cabin, so that it seats eight people in double club rather than six passengers. The Longitude also gets a new aft fuselage that’s designed to accommodate its 7,550-lb.-thrust Honeywell HTF 7000-series turbofans, the most powerful engines ever fitted to a Citation.

Final assembly of the first test aircraft is nearly complete, so it’s on track for first flight this summer. FAA type certification and entry into service are slated for third or fourth quarter 2017.

Company officials aren’t ready to discuss weight targets or fuel capacity, but it’s worth noting that the Hawker 4000’s wings and empennage were designed, sized and shaped for a 39,000-lb. to 40,000-lb. super-midsize business jet able to cruise in the mid-forties at Mach 0.78 to Mach 0.84. Based upon the heft of similarly sized super-midsize aircraft, the Longitude’s basic operating weight should be in the range of 24,000 lb. to 25,000 lb., in BCA’s estimation. Assuming the Longitude will have the same 14,600-lb. wing fuel capacity as the Hawker 4000, it should have no problem meeting or beating Textron Aviation’s advertised 3,400-nm maximum range, especially with the new Honeywell
engines.

The newest Citation has the longest range and largest cabin of any Cessna yet built.

Similar to most other super-midsize business aircraft, the Longitude will have a full-size baggage compartment aft of the lavatory and accessible inflight. Textron Aviation officials expect to earn approval for full-time access, regardless of cruise altitude.

The Citation developers concede that they’re a dozen or more years late with an entry into the super-midsize segment. Bombardier has delivered more than 550 Challenger 300/350 aircraft since 2003; Gulfstream has put 325 G200/G280 aircraft into service since 1999; and Embraer is ramping up production of its Legacy 500. Hawker Beechcraft (nee Raytheon Aircraft) also delivered 70 Model 4000 aircraft between 2008 and 2012. 

Meanwhile, the Falcon 2000S, Dassault’s premium contender, has added more than two-dozen units to the category during its first two years on the market.

But Textron is banking on the Longitude’s blend of low purchase price and operating costs, plus cabin size, range and cruise speed to wedge its way into this segment. Company officials are confident that the new model will appeal to a large number of loyal Citation customers seeking to move up to super midsize within the Cessna family.

Structure and Systems

Assuming that Textron Aviation will select the best features of the Latitude and Hawker 4000 to create the Longitude, what follows is a description of the aircraft based upon preliminary specifications released by the company and the original Hawker 4000 technical description published by Raytheon Aircraft. 

The Longitude will use the Latitude’s nose section, windows and 84-in. circular cross-section fuselage, a conventional aluminum alloy monocoque structure with stressed skins, hoop frames and longeron stringers, lengthened and strengthened for the longer aircraft. The Longitude’s Vmo will be 325 KIAS, a 20-kt. increase over the Latitude, requiring close attention to nose, forward bulkhead and windshield designs. The Hawker 4000 had a 350 KIAS Vmo, so the wing and the tail should have no problem handling the speed.

According to the Longitude’s specification and description dated October 2015, cabin height in center aisle is 6.0 ft., the cabin width is 6 ft. 5 in. and the floor width is 4 ft. 1 in. The cabin length is approximately 25 ft. from forward bulkhead to the rear of the aft lavatory. Based on other super mid-sized aircraft of similar size and range, BOW should be approximately 24,000-25,000 lb., but could possibly be lighter since the Latitude is an exceptionally light aircraft. 

The outer loft contours of the Hawker’s and Longitude’s wings are virtually identical, with the exceptions of the latter’s wingtip extensions and small winglets that add 5.3 ft. to the span. The longer wing also increases area to 537 sq. ft.

Longitude has a 31.8 deg. of leading edge sweep and 26.8 deg. of sweep at quarter chord (inner section) and its outer wing section has 28.6 deg. of sweep at quarter chord. The airfoil is a moderately super-critical, aft-loaded design, fine-tuned for long-range cruise at Mach 0.785. Considering the similar loft wing contours of the two aircraft, there will be less than a 6% range penalty for cruising at Mach 0.82. Mmo is Mach 0.84.

Textron will build the Longitude’s wing in-house. Slight internal structural improvements will streamline wing assembly and ensure precise design tolerances. The single-piece wing passes under the fuselage, so the structure doesn’t intrude into the cabin.

Longitude’s T-tail features a vertical fin with 45 deg. of sweep at quarter chord, 10.3-ft. height and 112.3-sq.–ft. area. It has a fully trimmable horizontal stabilizer with 25.9-ft. span, 33.5- deg. of sweep at quarter chord and leading-edge ice protection system. It is expected to have aluminum spars and ribs covered by graphite/epoxy sandwich construction skins.

The flight control systems of the Longitude will utilize manually actuated ailerons and elevators that provide high-fidelity aerodynamic force feel. Both ailerons have geared servo tabs that reduce control effort, plus a roll trim actuator connected to the left aileron servo tab. Servo tabs on the elevators also reduce control effort. The aircraft will have three multifunction spoilers on each wing, including a fly-by-wire (FBW) roll spoiler function that increases roll control authority. In addition, it features a triple redundant, FBW rudder with no mechanical links to the rudder pedals. The rudder system includes speed-proportionate rudder travel limiting to prevent overstressing the vertical fin, rudder trim, yaw damper and turn coordination functions.

Secondary flight controls include Mach trim, autopilot trim and pilot-actuated horizontal stabilizer trim, plus a stall barrier stick pusher. The multifunction spoilers have speed brake and ground spoiler functions, in addition to the roll spoiler function. Speed brake extension will be limited with flaps extended beyond takeoff and approach.

Each wing has two, four-position, electrically actuated trailing-edge flaps. On the Longitude, the positions are up, 7 deg., 15 deg. and 35 deg., fine-tuned to optimize second-segment climb performance.

All fuel is stored in left and right wing tanks. Assuming the its system is similar to the Hawker’s, total fuel capacity will be 14,600 lb., with fuel normally supplied to the engines by jet pumps powered by motive flow from the engine-driven fuel pumps. Jet pumps also scavenge fuel from low points to the feed-tank sumps. The Longitude’s DC-powered boost pumps will supply fuel for engine starting and cross-feed in the event of jet pump
failure. 

The Longitude will have a 28.5-volt DC primary electrical system rather than the Hawker 4000’s variable frequency, 115-volt AC, three-phase system. The aircraft’s engine-driven DC generators will have 500-ampere ratings, a 67% power increase over the Latitude. A third 500-ampere DC generator will be driven by the APU. And Longitude also will have a hydraulic motor-driven emergency DC generator function. Power inverters will supply AC power for windshield heat, thus the need for comparatively high output engine-driven DC generators.

Dual 26.4-volt lithium-ion batteries are standard on the new aircraft, offering significant improvements in power density, weight savings and recharge rates. Learning from the lithium ion battery meltdown experience in the CJ4 a few years ago, Textron engineers now are confident that the lithium ion battery technology is sufficiently mature to assure safe operation. Nicad batteries are a no-cost option, but they add 44.8 lb. to aircraft empty weight.

Following long-standing Citation design practice, cockpit circuit breakers are located on left- and right-side wall panels where they’re easy to see and move.

Dual, 3,000-psi hydraulic systems will power the rudder, multifunction spoilers, landing gear, wheel brakes, nosewheel
steering and thrust reversers. An emergency rudder system, powered by a 28-volt DC electric pump, provides a third power source for rudder actuation. Aboard the Longitude, Textron engineers have combined three functions — side-to-side power transfer, DC-powered aux pump and hydraulic motor-driven emergency generator — into a power transfer conversion unit, a first for the general aviation industry.

Long-travel, trailing-link landing gear, plus the large, low-mounted wing providing a generous ground effect cushion, will assure Longitude pilots deliver soft landing touchdowns. 

Long-life, high-capacity carbon brakes are actuated by a brake-by-wire system. The hydraulically powered nosewheel steering system is controlled through the rudder pedals and a side tiller. All three landing gear have dual wheels that are fully enclosed by the landing gear doors when retracted.

The Latitude and Longitude have 9.66-psid pressurizations systems, thus cabin altitude is 5,950 ft. at FL 450, the aircrafts’ maximum cruising altitude. No super-midsize aircraft in production has a lower cabin altitude. A single air-cycle machine supplies conditioned air to the cabin and cockpit. The cockpit and cabin have individual temperature controls.

The Longitude will feature dual 77-cu.-ft. oxygen bottles housed in the nose, meeting the requirements for FAR Part 135 operations. An optional 115-cu.-ft. bottle may be fitted in place of one 77-cu.-ft. bottle.

The Longitude’s ice protection system employs high frequency, vibrating ice probes to warn of ice accretion. Bleed air heating provides anti-ice protection for the wing leading edges and engine inlets. Probes, cockpit windows and static ports are electrically heated for ice protection. The horizontal tail uses an electromagnetic expulsive deicing system.

All internal and external lights are long-life LEDs.

Passenger Accommodations

The Longitude’s cabin cross-section is the smallest in the super-midsize class, having the same 6.0-ft. height but 5-in. less width than that of the Legacy 500, the next smallest contender. Passengers enter the cabin through a 31-in.-wide by 65-in.-tall airstair door. As noted, the interior of the aircraft feels commodious; BCA estimates interior volume to be approximately 855 cu. ft., including lavatory and aft baggage compartment. The aircraft in standard configuration will have a 1,500-lb. full-fuel payload. Each additional passenger will reduce maximum range by 55 nm to 60 nm, by our estimate.

The main double-club seating area, though, is 16.9 ft. long, affording slightly more spacing between facing chairs than the Challenger 350. The aircraft may be configured for eight, nine or 10 passengers. A three-place, side-facing divan may be ordered in place of the left aft pair of facing chairs. In addition, there’s an option for a right-side side-facing chair and compact galley that replaces the full-size forward galley in the forward vestibule. A belted potty seat is not available.

The standard configuration features a forward right-side galley approximately 6 ft. long, including a refreshment center, faucet and sink. The galley has dual hot beverage containers, an ice drawer, trash receptacle and compartments for catering storage, plus storage for bottle and canned beverages, tableware and condiments. Microwave and convection ovens are optional. Also optional is a metal-lined, countertop-level compartment with a 15-amp AC outlet, accommodating a portable espresso machine or coffeemaker.

Notably, there’s an optional crew jump seat that is stored in the left forward vestibule closet, just ahead of the main entry door acoustical curtain. It can be folded down facing forward into the cockpit for a third pilot or folded down facing aft into the galley for a cabin crewmember.

The main seating area has seven 13-in.-wide by 17-in.-tall windows on each side, including one in the emergency exit hatch positioned alongside the right rear passenger chair. That seat is fixed and is absent any wall-side armrest to meet emergency egress requirements. The other seven chairs track fore/aft and laterally on their bases, plus they swivel and recline. The chairs are different than those on the Latitude, having fixed left- and right-side armrests. Fore/aft aisle access is tight with adjacent seats tracked inboard.

Each seat has an overhead air vent, reading light and drop-down emergency oxygen mask, plus two USB power outlets and storage pockets in the cabin sidewalls. But there are only two AC power outlets in the cabin. Foldout worktables with overhead lights are provided for each pair of facing chairs. Overhead valence panels hide the downwash lights.

The cabin management and entertainment system (CMS) may be controlled by means of a touch-screen panel in the galley, a dedicated remote control or personal electronic devices running the CMS app. The CMS will offer moving map, flight information, cockpit/ATC audio, video streaming of licensed content and optional XM satellite radio entertainment, plus a high-fidelity stereo sound system. The entertainment system supports wireless personal display devices. An audio/video on demand (AVOD) capability is being studied. A two-channel Iridium satcom phone and U.S. air-to-ground Wi-Fi/Internet access system are standard. An optional moderate speed Inmarsat satcom Internet system is available. It may replace or supplement the standard air-to-ground Wi-Fi/Internet system. The CMS includes a 22-in. high-resolution monitor on the forward cabin bulkhead. A second 22-in. monitor for the aft cabin bulkhead is optional.

The aft lavatory features a right-side, high waste capacity vacuum toilet and a left-side sink with hot and cold running water. An AC power outlet is available for personal grooming equipment. Aft of the lavatory, there is a full-time access, 96-cu.-ft., internally accessible baggage compartment. A 26-in.-wide door below the left engine nacelle provides external access to the compartment.

More Crowded in Super-Midsize

The Longitude will enter a crowded super-midsize market, joining the Bombardier Challenger 350, Embraer Legacy 500, Gulfstream G280 and Falcon 2000S. Some might add that the Legacy 600/650 competes on price and range as well.

Each of these aircraft has a distinct personality, providing buyers with plenty of choices in aircraft with 7 to 8 hr. of endurance. What sets the Longitude apart is its $23.9 million base price, lengthy list of standard features and conservative approach to new technology. It’s so well equipped that if you load it up with most popular options, including dual Honeywell Laseref IV, along with HUD/EVS, plus FANS, CPDLC and Link 2000+ and IFE, you’ll not push the retail price above $25 million.

Admittedly, the cabin cross-section is lean for a 7.5-hr. airplane, especially with its more amply sized chairs. But as the aircraft has only four full-flat berths for overnight missions, there’s sufficient space for close friends on flights between the U.K. and North America. For 4- to 5-hr. transcontinental U.S. flights with all eight seats occupied, there should be ample room to move about the cabin with the seats tracked outboard.

Most importantly for Textron Aviation, the Longitude is going to be available in 2017. It provides a true midsize jet in the Cessna family into which operators of smaller, shorter range Citations can advance. Without it, Textron risked losing more customers to the competition.

The Longitude also provides an interim bridge product while Textron sorts out propulsion snags with its 4,500-nm range, large-cabin $35 million Hemisphere jet. The aircraft is slated to be powered by twin Snecma Silvercrest turbofans, but engine development has been slowed while the French manufacturer reworks a fuel/oil heat exchanger to meet new revised specifications and improves active clearance control of the engine case to assure fuel efficiency and durability targets. Assuming Textron Aviation can get the Hemisphere back on schedule, first flight is scheduled for 2019 and, presumably, entry into service the following year.

The Latitude, Longitude and Hemisphere represent a sea change for Textron Aviation. With the demand for light jets remaining sluggish, the firm is moving up into larger aircraft as fast as possible to build market share, all the while maintaining its historic conservative development approach.

“Promises made, promises kept” used to be Cessna’s most popular marketing mantra. “It’s a sure thing” was another well-known slogan. Because of Textron’s low-risk approach, the Longitude won’t be the biggest, the fastest, the longest range or the highest technology super-midsize aircraft. 

But it’s impressively well-equipped in standard form. It’s highly probable that it will meet or exceed its performance targets. And it is bound to be one of the most reliable new aircraft upon service entry. For all those reasons and at its attractive price point, it’s getting serious consideration by many prospective customers. 

This article was originally published on February 25, 2016.