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  • Flight test: Cessna Mustang - Easy rider

Flight test: Cessna Mustang - Easy rider

Cessna has avoided branding its Mustang as a VLJ, but is that vindicated by the aircraft's performance? We flew the newest addition to the Citation line to find out

Cessna markets its aircraft as a "sure thing", and sure things seldom engender passion, but the Citation Mustang looks set to buck this trend. With the exception of the Citation X, it is easily the most rakish Cessna jet. Its fuselage and wing appear well proportioned, with the T-tail giving the aircraft an aggressive look. And although the airframe is of conventional aluminium construction, the Mustang's surface finish is extremely smooth, prompting some to ask if it is a composite design.

    
Click on the image to enlarge

Flight International was able to saddle up the newest Citation and fly the Mustang from Wichita's Mid-Continent airport. Cessna test pilot Don Alexander highlighted some of the entry-level jet's strong points during the pre-flight walk-round inspection. There are two exterior baggage compartments, one in the nose and one in the tailcone. Both are easily accessible from ramp level, with the rear compartment featuring a ski tube. For flight into known icing conditions, the leading edges of the wing and both horizontal and vertical stabilisers are booted. The eight vortex generators embedded in each wing leading-edge boot and the two ventral strakes positioned under the tailcone were added during flight testing to improve handling qualities, particularly for inexperienced pilots.

Entry is via a manually operated door with a sill-mounted two-step ladder. Once brought to the closed position, four powerful magnets hold the door closed so the eight locking pins can be easily engaged. The constant cross-section fuselage and dropped aisle provides a height of 1.37m (4.5ft) and width of 1.4m for a cabin that felt markedly roomier than the Eclipse 500's, the cross-section of which is not only smaller, but decreases as you move aft. The 2.97m-long passenger cabin is arranged in a club-four layout, with a non-belted toilet and cabinet opposite the entry door. The fittings and leather seats are of a high quality, on par with luxury automoblies, with three different colour schemes offered.

The aircraft's cockpit is separated from the cabin by two sidewall cabinets and a curtain. While dimensionally not markedly larger than the Eclipse's flightdeck, I found it easier to get settled into the Mustang's left seat. The four-way manually adjustable seat allowed me to find a comfortable position, with the small centre pedestal-mounted throttles falling easily to hand.

One minor gripe that I have with other Citations is that the column-mounted yoke is too high. The Mustang has a panel-mounted yoke, and its height felt right.

My first exposure to Garmin's G1000 integrated avionics suite was in Cessna's 182T Turbo Skylane, and while I was impressed with it then, the installation in the Mustang is stunning. Three large liquid crystal displays dominate the instrument panel. Each pilot has a 10.4in (26.4cm)-diagonal primary flight display (PFD) and shares a centre-mounted 15in multifunction display (MFD). Buttons or soft keys at the bottom of the PFD and MFD bezels control the displays. In addition the PFDs have dedicated knobs for cursor control, range, barometric and communication functions.

  
Straight wing gives slow stall speeds

Trend vectors

The PFDs are arranged in a standard format, with handy 6s trend vectors provided on the airspeed and altitude tapes. Communication and navigation radio information is presented at the top of the display, with the central portion dedicated to flight mode annunciators for the flight director and three-axis autopilot. A smaller version of the MFD's navigation map can be presented on the lower left-hand corner of each PFD to increase situational awareness.

The engine information and crew alerting system and a large moving map display are presented on the MFD. Unlike the G1000 installation in the Skylane, the FMS in the Mustang is controlled by an alphanumeric keyboard panel mounted aft of the throttles. This dedicated panel eased the task of data entry compared with the heavily cursor-dependent operation in the Skylane. One desirable capability the G1000 lacks is the ability to upload previously programmed routes from a ground-based computer, directly into the FMS.

Unlike the Eclipse, which has a heavily software-dependent, nearly pure glass panel, the Mustang retains the feel of the Citations that came before it. Three conventional standby instruments are located above the MFD. Dedicated digital audio control panels mounted outboard of the PFDs provide ready access to the basic functions of intercom and audio volume. System and light switches are located on "tilt" panels below the instrument panel. The pressurisation panel is remarkably simple, the FMS providing departure and arrival field elevations as well as selected cruise altitude. A small number of circuit breakers are on a panel on each sidewall.

After completing the pre-start checklist, an external power cart was used to start the 1,460lb-thrust (6.49kN) Pratt & Whitney Canada PW615F turbofans. Pushing the start button on the left-hand tilt panel engaged the starter, and moving the throttle out of the cut-off position allowed the dual channel full-authority digital electronic engine control (FADEC) to manage the start.

Unlike the FADECs in the Eclipse, which rely solely on the aircraft's electrical system for power, the Mustang's have dedicated permanent magnet alternators to act as a back-up in the event of total electrical failure. Each engine reached idle in less than 30s, with exhaust gas temperature peaking at 540e_SDgrC (1,000e_SDgrF). Setting the electrically driven flaps to take-off/approach (15e_SDgr) and conducting a control sweep were the major items on the post-start checklist.

Safe taxiing

During the taxi-out, Alexander used the MFD's range knob to select G1000's "Safe Taxi" display. Safe Taxi provides a scalable airport diagram that shows FMS-derived aircraft position in real time - the same functionality found in similar systems in the Gulfstream G550 and Airbus A380. In low visibility, Safe Taxi will undoubtedly increase situational awareness and improve safety. Nosewheel steering is controlled by the rudder pedals, and allowed accurate tracking of taxiway centrelines. The nosewheel can caster for tight-radius turns, a feature I did not investigate during my flight.

Once on the runway I advanced the throttles to the take-off position, the FADEC smoothly spooling the engines up to an N1 (fan speed) of 91.2% on the 14e_SDgrC day. Acceleration was brisk, with Alexander calling "rotate" at 91kt (170km/h) indicated airspeed (V1/VR) V2 was 97kt. Approximately 12kg (26lb) of aft yoke force was required to attain the desired lift-off attitude of 10e_SDgr. Landing gear and flap retraction caused negligible changes in pitch forces. During the acceleration to 170kt for the climb, the yoke-mounted pitch trim switches allowed me to easily zero out pitch forces. Power was retarded to the climb detent as the aircraft passed 1,000ft above ground level (2,000ft above mean sea level).

Once on a vector for the working area, I engaged the autopilot for the climb. In the pitch axis the flight-level change mode was used, airspeed being controlled by pitch attitude. Heading mode was used in the roll axis, allowing for easy and precise following of ATC vectors. Passing flight level 270 a constant Mach of 0.44 was held until levelling off at FL340. Total time from brake release was 17min 30s for an aircraft that weighed 3,590kg at lift-off (including 975kg of fuel). Cessna's preliminary performance numbers indicate that, on a standard day, a climb to 35,000ft from sea level at maximum take-off weight (3,925kg) will take 18min and burn 130kg of fuel. At the same conditions, a climb to the aircraft's 41,000ft ceiling is estimated to take 27min and burn 163kg of fuel.

Cruise guarantee

Level at FL340, the power was retarded to the cruise detent passing 195kt. The 3,452kg aircraft stabilised at 200kt with a total fuel flow of 290kg/h. At ISA+5ºC an indicated Mach of 0.588 was held with a resulting true airspeed of 345kt. Cessna has promised a maximum cruise speed of 340kt, and my glimpse of the Mustang's capabilities on a non-standard day indicates expectations should be met.

To approximate a maximum range condition I pulled the power back to 86.9% N1 for a total fuel flow of 227kg/h. The airspeed bled off to 178kt indicated and at M0.516 a true airspeed of 301kt was held (Cessna's long-range cruise speed). While not at identical conditions, this approximated the maximum thrust cruise point I performed with the Eclipse 500 in April. The Eclipse's total fuel flow then was 192kg/h, about 15% less than the Mustang's. Cessna projects a NBAA instrument flight rules range with four occupants of 2,130km (1,150nm). The Eclipse's range at like conditions is quoted as 2,080km. The Eclipse may have nearly the range of the Mustang, but it is doubtful it will have the same high-speed cruise capability.

While at Mach 0.516, I left the cockpit to sample the Mustang's cabin in the cruise. Noise was low, on par with other business jets I had flown. After returning to the cockpit I did a number of 45e_SDgr and 60e_SDgr angle-of-bank steep turns. Roll control was crisp, with no airframe buffet at the elevated g loadings. During the descent to medium altitude I accelerated the Mustang to the MMO of 0.63, where aircraft oscillations from sharp control inputs in all three axes were well damped.

With the throttles at idle and speed brakes deployed, a 6,000ft/min (30.5m/s) descent rate was held at MMO. In the event an actual emergency descent is required, Cessna recommends extending the landing gear. Alexander says he has observed descent rates in excess of 10,000ft/min at those conditions. The descent was continued at 250kt indicated (VMO) until the aircraft was levelled off at 15,500ft for an investigation of the Mustang's low-speed handling qualities.

The first stall was in a clean configuration with 670kg of fuel. The aircraft was slowed in idle power in level flight. A green dot was displayed on the PFD's airspeed tape at 117kt, approximately 1.3V stall for the current conditions. At 90kt the aural stall warning sounded. Ignoring the warning I continued to pull aft on the yoke, feeling light airframe buffet at 85kt. At 83kt, 7kt below the stall warning, the nose dropped while the wings remained steady and level. Recovery from the stalled condition was by relaxing aft yoke pressure and advancing the throttles in a slight descent.

The last stall was in a landing configuration, gear down and flaps at 35º. With the power again at idle in level flight the stall warning horn sounded at 75kt. Continued yoke back pressure further slowed the aircraft, where the right wing dropped at 70kt. I was able to stop the roll with left rudder, with normal flight conditions again regained primarily by relaxing back pressure and initiating a descent. During the stalls and other manoeuvres I found the Mustang's flight controls to be well harmonised - from a handling qualities perspective it was the most enjoyable Citation I have flown.

WAAS capable

A visual flight rules descent was initiated to 5,000ft MSL for transit to Hutchinson, Kansas for a GPS approach. The G1000 avionics suite has dual WAAS-capable GPS receivers, the wide-area augmentation system offering increased accuracy, 3m as opposed to 100m for basic GPS. WAAS also supports a pseudo glideslope, giving aircraft a near-precision approach capability based solely on GPS.

WAAS LPV (lateral precision with vertical guidance) approach procedures are being published for general aviation airports. Unfortunately, the GPS approach we flew to Hutchinson's runway 13 was not an WAAS LPV procedure. The approach was flown on the autopilot, with manual control of airspeed. NAV was selected for the lateral mode, allowing the aircraft to automatically fly to the various waypoints on the approach. VNV (vertical navigation) was the vertical mode, the aircraft pitching to maintain the proper altitude or descent path.

Inside the final approach fix the Mustang followed a 3e_SDgr glidepath, in essence a pseudo-glideslope like that found on a WAAS LPV approach to the runway. Opposing traffic forced us to abandon the approach before to minimums, but the combination of WAAS-capable GPS and a VNAV descent may allow Mustang pilots to get to their destination while other aircraft are diverting.

Return to Wichita was via radar vectors for a hand-flown instrument landing system approach to runway 1R. While it was not operational for our flight, the Mustang comes standard with a Garmin traffic information system (TIS), which gives the pilots the same traffic information ATC is seeing. An optional Honeywell traffic advisory system (TAS) will be available in July 2007 and provides a view of opposing traffic derived from aircraft transponders, independent of ground-based ATC radar. While Wichita's Mid-Continent airport was not overly busy, I missed the increased safety and awareness afforded by a TIS or TAS.

The small pitch force change with take-off/approach flap selection at 160kt on base leg was handily countered by the pitch trim. Landing-gear extension caused negligible changes in pitch forces, and forces introduced when landing flaps were selected just before glideslope intercept were easily trimmed out. Final approach reference speed (VREF) was 91kt with a target speed (VAPP) of 98kt for the 3,121kg aircraft. The V-bar flight director provided excellent cues, allowing me to track the localiser and glideslope.

On final an N1 of around 41% on each engine was required to maintain 98kt. I started the round out at about 10ft, and the Mustang floated a bit before softly touching down, cushioned by the trailing-link landing gear. Once on the runway Alexander selected take-off/approach flaps for the roller. With the throttles in the take-off detent Alexander called "rotate" at 95kt.

After gear retraction accelerating through 130kt Alexander simulated an engine failure by rapidly pulling the right throttle to idle. The resultant yawing motion was easily countered by the rudder, and I slowed the aircraft to 110kt for the single-engine climbout. Steady pedal forces were less than 35kg, and the available rudder trim zeroed out forces required for co-ordinated flight. Once level on the downwind leg I centred the rudder trim, countering yawing motion due to power changes with manual rudder inputs.

The flaps were kept at take-off/approach for the entire pattern and simulated single-engine landing. Cessna recommends full flaps in this situation only for only for short runways. An N1 on the left engine of 61% was needed to hold a target speed of 98kt on final. While not a centreline-thrust aircraft, pulling the left throttle to idle for the full stop landing required little rudder input to keep the nose tracking down the runway during the flare manoeuvre.

Smooth braking

Once on the ground I deployed the speed brakes with the throttle-mounted switch, putting more weight on the main landing gear. The motor-driven hydraulically actuated wheel brakes smoothly and rapidly slowed the Mustang to taxi speed for runway turn-off. While the runway at Wichita was dry, the Mustang does have digital anti-skid to provide locked-wheel protection at speeds above 10kt. While no attempt was made to determine the ground roll for my single-engine landing, Cessna lists a landing runway length of 728m at sea level and standard day conditions for a normal two engine landing. Taxi back to Cessna's ramp and shut down were non-eventful, the Safe Taxi display again providing good guidance on an unfamiliar airfield.

During my 2h flight in the Mustang I was pleasantly surprised by its robust feel and well-harmonised controls. The Mustang felt and flew like a Citation, not a jet-powered light aircraft.

The emergence of affordable jets has ignited a passion in general aviation not seen for a long time. Although it avoids the very light jet branding embraced by Eclipse, preferring to call its Mustang an entry-level jet, Cessna has developed a capable, well-equipped six-seat twinjet that can take four people 2,130km on a tank of gas and costs $2.6 million - $1.5 million less than any other jet in the Citation range. With orders in hand for 250 aircraft, and deliveries to begin early next year, the Mustang is clearly off to a strong start in the small jet race.




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