The Power of Ten

Sometimes a manufacturer just needs to make a statement. For the Cessna Aircraft Company, the new Citation X fulfills this function in spades. Known for years as builders of rather modest-looking and -performing airplanes, Cessna really turned the tables when it produced this airplane. With its blistering maximum cruise speed of 0.92 Mach, 36,000-pound ramp weight, huge 6,400-pound-thrust Allison AE3007C engines, 3,720 fpm initial rate of climb, 51,000-foot maximum certified ceiling, and muscular good looks, the Citation X is everything that Cessna's previous Citations weren't.

It's as though the company had finally had it up to here with the "Slow-tation" and "NearJet" jokes that have plagued the Citation series from the very beginning, 25 years ago. Then, the first Citation — the model 500 — plodded along at 340 knots (on a good day) and had an IFR range of some 1,000 nautical miles. The "Ten," as it's commonly called, blows its doors off with true airspeeds 200 knots faster and ranges three times that of the first Citations.

Although the passengers have it pretty good back in the Ten's luxo cabin, it's the pilots who'll really enjoy this machine. The cockpit is roomy, the panel is filled with Honeywell's Primus 2000 avionics suite (a Collins package is available as an option), and the general impression is one of having stepped into a modern airliner's front office. The Primus 2000 consists of five 8 X 7-inch color cathode-ray tube displays that stretch the width of the instrument panel. The system comes with just about every feature you'd ever want as standard equipment: EICAS (engine instrument and crew alerting system), an attitude and heading reference system (AHRS) that uses a fiber optic gyro instead of the old "spinning iron" gyro systems, the FMZ-2000 Flight Management System, dual autopilots and flight directors, the Primus 870 turbulence-detecting Doppler weather radar, a 12-channel GPS receiver, and a radio altimeter, to name just a few components. A traffic alert and collision avoidance system (TCAS II), lightning detection, a backup Laseref III inertial reference system, GPWS, HF radios, satcom, a flight data recorder, and — get this — an ADF are a few of the avionics options. SmartPerf software, an FMS enhancement that automatically computes takeoff, cruise, and landing calculations is also available.

My introduction to the Ten came on a blustery November day at Cessna's ramp at Wichita's Mid-Continent Airport. My flight would be a positioning trip to New York's La Guardia Airport, where a prospect awaited his introductory ride. During the walkaround preflight inspection it's difficult not to be impressed by the airplane's sheer size and those massive Allison engines. The pronounced area ruling of the fuselage aft of the wing's trailing edge is quite dramatic. This feature, characterized by the narrow empennage abeam the engine nacelles, reduces the drag caused by shock waves at the Ten's lofty cruise speeds and was refined through studies of computational fluid dynamics and exhaustive wind tunnel testing.

For such a high-performance jet, the Ten's wing is remarkably free of the usual assortment of slow-speed lift augmentation devices seen on wings optimized for high cruise speeds — let alone at 92 percent of the speed of sound. There are leading edge slats, but there are none of the winglets, stall fences, and vortex generators so common in other business jets.

Demonstration pilot Ray Wellington took the right seat and began running the checklists. The tailcone-mounted auxiliary power unit (APU) was started first, and then the big Allisons were brought to life via a pneumatic start — another airliner-style touch. Unlike the starting procedures used in smaller engines (using battery power to turn a starter motor), pneumatic starts involve using an APU's bleed air to make engine starts.

Dual-channel FADEC (full authority digital engine control) makes starting the APU and engines a snap. You just push a button and the FADEC does the rest. More problematic is programming the FMS. One of these days, I swear, I'm going to master this button-festooned Rubic's cube; but in the meantime, I'll rely on people like Wellington, who fly with FMSs on a day-in, day-out basis and whose fingers seem to dance across the keypads in a blur.

Our airplane's ramp weight came in at 32,082 pounds, which included two passengers, 475 pounds of baggage, and 9,790 pounds (about 1,467 gallons) of fuel. Maximum fuel capacity is 13,000 pounds. It was 35 degrees in Wichita, and our takeoff speeds worked out to be a V1 of 117 knots, a VR of 117 knots, and a V2 of 127 knots. These speeds were bugged on the vertical tape airspeed display on the primary flight displays (PFDs), and soon we were off to the active. Slat and flap settings of 30 degrees and 15 degrees, respectively, were used for takeoff.

A tiller is used for taxiing and for directional control on the takeoff run up to 80 knots. Setting takeoff power is a simple matter of advancing the thrust levers to the TO position; then the FADEC sets the correct amount of power for the conditions at hand. Acceleration occurred fairly quickly, as you might expect from engines producing a total of 12,800 pounds of thrust, and soon my hand was off the tiller and on the yoke. V1 and rotation quickly became things of the past, and N754CX settled into a satisfying, 3,500-fpm climb rate. I ought to mention that there was a nice 20-knot crosswind for the takeoff and that the Ten handled it with a minimum of corrective inputs.

I also ought to mention that during the takeoff and initial climb, the fuel flow registered 2,000 pph per side. That comes to a total fuel flow of some 600 gph — a figure large enough to compel standing ovations from several sheikdoms. That said, it's important to raise two points: 1) What do you expect from engines designed to propel an airplane to 0.92 Mach? and 2) You don't fly any turbine airplane efficiently at lower altitudes. The Ten is most fuel efficient above FL410, so the objective is to climb up there as quickly as humanly possible.

This is not too difficult. In less than 20 minutes, N754CX makes it to FL410, where the thrust levers are pulled back to the CRZ click stops and the ship settles into a 513-knot cruise, burning 1,120 pph per engine. A call-out on the PFD tells us that we're now going 0.896 Mach, even though indicated airspeed is 267 knots. Under current conditions, our airspeed redline is 278 KIAS and our stall speed has risen to 127 KIAS in the rarified air. This amounts to a very large spread between stall and high-speed buffet. Even at FL510 — the Ten's maximum operating altitude — the usual concerns over the "coffin corner" are nonissues, according to Cessna. Up there, the airspeed envelope is 60 knots wide — a huge margin compared to the 10- and 20-knot margins of some other business jets certified to fly that high.

Other PFD call-outs give bad news. We're flying in ISA-plus-10 temperatures, there's a 106-knot left crosswind component, and a mere six knots of tailwind. The above-standard temperatures explain why we're not making the advertised 0.92 Mach high cruise speed, but Wellington feels that there's only one way to remedy the tailwind problem. Climb higher.

No problem. Soon we're climbing at 0.82 Mach, and level at FL450. Now we're taking advantage of a 32-knot tailwind and burning 860 pph per side, but higher-than-standard temperatures still conspire to lower our cruise Mach number to 0.798. (Under standard conditions, we'd have been tooling along at 0.84 Mach.)

We ultimately decide to make FL410 our cruising altitude, where we turned in 0.87 Mach. By this time, we're over Ohio and the trip is more than half over.

The Allisons provide the Ten with its greatest strengths and its greatest weaknesses. Strength, in that they can propel the airplane to altitudes so high (above the troposphere) that winds aloft cease to be factors. This is the strategy for flying westbound on 1,000-nm-plus legs with strong winds at lower altitudes. Down low, when winds are favorable, you can floor the Allisons and peg the Mach meter or cut back into a fuel-saving, long-range cruise setting and fly at a "slower," 470-knot/0.77-Mach cruise speed. There are weaknesses, in that the Allisons, if held to lower altitudes by ATC or other restrictions, will suck the fuel down and limit range considerably. Also, cruising at 0.92 Mach requires so much fuel that the airplane's maximum range is compromised.

The Ten's payload/ range chart claims that the airplane will carry four passengers and two crew 3,000 nautical miles with IFR reserves. This assumes no wind, standard conditions, a 0.82 Mach cruise, and a step-climb to FL470. What about headwinds and bigger passenger loads, you say? Let's put it this way: Nonstop coast-to-coast trips both east- and westbound should not be a problem, even when operating the Ten at 0.92 Mach, and even when carrying eight passengers — unless headwind components are higher than 150 knots, according to Cessna.

Eastbound, New York-to-London nonstop Atlantic crossings are similarly possible. But while nonstop London-to-New York westbound crossings can be accomplished, it wouldn't be wise to count on them in the wintertime, when headwinds are strongest. A fuel stop in Iceland will probably be necessary.

Back to the flight. Somewhere near Reading, Pennsylvania, I realize that I feel more at home in the airplane. The panel layout is superb, and by this time I've come to terms with the autopilot, the PFD, and the other displays and their controls, as well as the radio management units. Hand-flying turns out to be no big deal, just a little heaviness in the controls — but again, this is a 36,000-pound airplane. We've flown beyond an undercast that persisted since Wichita, and night falls. I look at the lights of the small towns below, then see an airplane's strobes far below us. The TCAS chimes, reporting his position and altitude on the multifunction display.

I don't really want to leave the cockpit but feel a duty to check out the cabin. Cessna compares its dimensions to that of the Falcon 50, saying that it's one foot longer. The interior of N754CX is set up in an eight-seat, double-club arrangement, which is typical of most completed Citation Xs. There's a galley and beverage center up front, along with an entertainment center that pipes music and feeds videos to each berthable seat. At the other end of the cabin is a lavatory. In all, there's everything you need for a trip that could last as long as 7 hours, which is the Ten's approximate maximum endurance.

A glance at the bulkhead-mounted Airshow display indicates that we're now over Allentown. Time to go back to the cockpit.

ATC sends us down to 12,000 feet, then 7,000, then 2,000 for our approach to La Guardia. The spoilers help us to hustle down, and cause only a little rumble, at least up front. More noticeable is the roar of air caused by our 320-knot descent speed. A tug on the thrust levers, a little bit of spoiler, and some aft stick pressure get us ready for the 250-below-10,000-feet speed restriction. Purple airspeed and altitude trend vector symbols on the airspeed and altitude tapes make that easy. They predict the airspeed and altitude that we'll be flying in the next 6 seconds and are very, very useful in making precise power settings on approach. Night has fallen, and the sky seems alive with airplanes. The TCAS goes off repeatedly, calling out whatever traffic that ATC fails to mention. Fifteen minutes of this and you'll decide that this is an option definitely worth having.

Soon we're set up on the localizer for the ILS approach to Runway 31. The flaps and slats go out, the angle-of-attack gauge is made to read 0.6 units, and I slow first to 124 knots, and then to our calculated VREF of 118 knots.

The only unusual thing about landing is that you must exert some forward stick pressure to fly the nose to the runway and hold it there. Otherwise, there's a chance that the nose could rise as reverse thrust is selected, Wellington says.

One of the FMS pages sums up the trip. We flew 1,106 nm in 2 hours, 29 minutes, at an average true airspeed of 444 knots and an average groundspeed of 463 knots, and burned 5,440 pounds (about 815 gallons) of fuel. The higher-than-standard temperatures and quirky winds aloft trashed our hopes of flying faster.

The Ten will go down in aviation history as a unique business jet. In fact, it's won the 1996 Robert J. Collier Trophy for the top aeronautical achievement in the United States. It has a speed advantage over the competition and the capability to merge that speed with economy of operation. The Allisons have 3,000-hour hot section inspection intervals; 6,000-hour intervals between overhaul; and a 5-year, 2,500-hour warranty. Allison also warrants life limits of 12,000 cycles on compressor and turbine discs. In addition, Cessna provides a 5-year warranty on the airframe and avionics.

The Citation X seems to have found its niche. In 1996 seven airplanes were delivered. This year Cessna anticipates that another 27 will go out the door, and the company says that it is producing Tens at a rate of 2.5 airplanes per month. Want to buy one? Come up with about $15.5 million and be prepared to wait until mid-1998, when the next delivery slot opens up.

It will be interesting to see how Cessna tops the Citation X. The airplane carries a sense of finality about it: the tenth in the series, the fastest Citation yet, even the Mach number. How much faster can a business jet go without encountering really prohibitive fuel consumption, revolutionary design requirements, or market resistance? Gulfstream found out the answer to that question in 1990, when it walked away from its supersonic business jet concept. Will Cessna pick up the baton?