Flying the aircraft back to back allowed me to note how the CRJ's fly-by-wire rudder compares with the CRJ's conventional one. From a pilot's perspective, the NextGen line offers several advantages. The altitude heading reference system has been upgraded to laser ring gyros from the previous flux valve units. With proper training and authorisation, the head-up guidance system can allow for reduced visibility take-offs as well as a Category IIIa landing capability.
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Flying the aircraft back to back allowed me to note how the CRJ's fly-by-wire rudder compares with the CRJ's conventional one. From a pilot's perspective, the NextGen line offers several advantages.
The altitude heading reference system has been upgraded to laser ring gyros from the previous flux valve units. With proper training and authorisation, the head-up guidance system can allow for reduced visibility take-offs as well as a Category IIIa landing capability.
Unfortunately, neither the EFB nor the head-up system were installed on the test aircraft, which was a production example in Brit Air colours. The inspection itself was straightforward, and the longer fuselage and larger wing were obvious. I used the seat alignment balls on the centre pillar to gain a comfortable seating position. With a few minor exceptions, the flightdeck is identical to that of the CRJ I had flown earlier. The six 6 x 7in 15 x 18cm cathode ray tube displays - leading edge when the Pro Line 4 avionics suite was first deployed - seem merely adequate in today's marketplace.
Aircraft systems are primarily controlled by switches and push-button lights on the well-arranged overhead panel. The flight guidance control panel on the glareshield provided ready access to autopilot and flight-director modes, and the forward instrument panel was arranged in the conventional manner, each pilot having a dedicated primary flight display and multifunction display. Two flight management system control units are at the head of the centre pedestal.
After completion of pre-start flows, both engines were started using bleed air from the tail-mounted Honeywell auxiliary power unit. Post-start flows were easily accomplished and the flaps were set to position 8 for our take-off. Once the aircraft was rolling, idle thrust was sufficient to move at a comfortable taxi speed. During the taxi to Runway 06, I found the steer-by-wire nose wheel steering allowed me to precisely track taxiway centrelines.
Mirabel is an uncontrolled field and, after visually clearing final, we lined up on Runway Bombardier lists a maximum take-off weight of 40,kg 90,lb for the base line CRJ With 7,kg of fuel 8,kg maximum our take-off weight of 31,kg was not representative of an actual airline operation.
The aircraft cleared the runway after a 1,m 3,ft ground run, about one half of the certificated take-off distance, which includes clearing a 35ft obstacle at maximum take-off weight. After cleaning up the aircraft, and when passing 1,ft above the ground, I retarded the throttles to the "climb" detent.
A turn was made to the north, air traffic control clearing Canadair into one of Bombardier's local test areas. I hand-flew the aircraft until we passed 10,ft, where a climb speed of kt was captured and held by the autopilot. With the throttles in "climb" detent, the full-authority digital engine controls kept the optimum N1 setting.
When the aircraft passed 32,ft, Mach 0. Time from brake release to level-off was only about 18min. Once level, I established M0. I found the airspeed tape's trend arrow allowed me to expeditiously set and hold the desired speed. Next, the power was increased and an M0.
To a working airline pilot, the prospect of being stuck behind slower traffic is never appealing. Bombardier's CRJs can definitely keep up with traffic - and even outpace aircraft such as the Boeing Classic.
The ambient noise level was reasonably low, on a par with the flightdeck of a For the flight we used David Clark headsets, which further reduced background noise. At altitude I found the flightdeck a pleasant environment to work in. Given the CRJ's 1,nm range, with passengers and IFR reserves, legs with three-plus hours of block time will not be out of the question.
While still at altitude, Litavniks put the flight-control page schematic up on one of the centre multifunction displays. The rudder schematic showed actual rudder displacement against a lateral scale. Nothing unusual in that, but what was interesting was the two sets of lateral limits displayed. Large hash marks indicated the ultimate displacement limit, while smaller moving ones inside them showed the displacement allowed given the current flight conditions and aircraft configuration.
At FL and cruise conditions, only about a quarter of maximum rudder displacement was available. While almost all transport aircraft have some sort of rudder travel limiter, what distinguishes the CRJ is how the FBW scheme is implemented. In the CRJ, the pilot always has full rudder pedal travel, only the resultant rudder displacement is reduced.
Reducing rudder pedal travel is another method of limiting rudder displacement. Reduced rudder pedal travel has, however, been cited as a contributing factor in several accidents. Bombardier's decision to develop a fly-by-wire rudder for the CRJ, instead of using the proven existing design, may have been driven more by a corporate strategy to gain fly-by-wire experience for the forthcoming CSeries than by any pressing technological issues unique to the CRJ At MMO, small, sharp control inputs in all three axes elicited a well-damped response.
To slow the aircraft, I retarded the throttles and extended the speedbrakes to their full open position. There was a noticeable burble but no untold pitching motion as the aircraft slowed. I stowed the speedbrakes and continued the descent to 18,ft, where I would be able to evaluate the CRJ's handling characteristics.
I did these with my feet on the floor, allowing the digital yaw damper - part of the rudder control scheme - to co-ordinate the turns. Roll in and out of the turns was crisp, with good harmony between the pitch and roll axes. At the higher speed, aircraft response was crisp and the turns well co-ordinated.
Next, I did a wings-level sideslip and found breakout forces for the rudder to be about 7kg. Full travel required about 20kg of force, with rudder deflection roughly proportional to pedal forces. Allowable rudder deflection increases as speed decreases and the flaps are extended. Loss of an engine roughly doubles the available rudder deflection at any given speed and flap setting.
Two stalls were accomplished next. The first was in a clean configuration and with a fuel load of 6,kg. Ignoring the slow speed warning on the primary flight display's airspeed tape, the stickshaker actuated at kt.
The wing remained steady and level as the airspeed continued slowing. At kt, the stick pusher fired, prompting me to recover the aircraft by lowering the nose to break the stall and advancing the throttles.
Adding power caused a slight nose-down pitching motion, further aiding the recovery. The last stall was in the landing configuration, flaps set to "45" and gear extended. The shaker activated, slowing through kt with the pusher firing at kt. As with the clean stall, control in all three axes was good at these very slow speeds. The wings remained level and displayed no tendency to oscillate or drop. After recovering to normal flight conditions, the gear was retracted and flaps retracted to position "8".
At kt, a half-amplitude rudder doublet was used to excite the CRJ's Dutch roll mode. With the yaw damper disengaged, aircraft response was lightly damped with a roll to yaw ratio of about one to one. Engaging the yaw damper served to quickly damp out the motion. Aircraft motion from another rudder doublet, with the yaw damper engaged, was quickly damped out without pilot intervention.
Return to Mirabel was via radar vectors to an instrument landing system approach to Runway Litavniks installed the approach procedure in the flight management system, which auto-tuned the navigation radio to the ILS localiser frequency - a handy feature.
Nearing the final approach course, I disengaged the autopilot and hand-flew the aircraft. Extending the landing gear and the initial flap extension to position 8 caused minor changes in pitch force, easily countered with pitch trim.
Flight-director guidance allowed me to roll out on course, as I continued to slow the aircraft. The flaps were extended to position 45 and aircraft slowed to a target speed of kt as we approached glideslope intercept. A good amount of pitch trim was needed to null out the change in pitch forces due to flap extension. Again, the flight director provided excellent cues, allowing me to easily capture and track the glideslope.
At about 30ft above ground level I started a slight pre-flare, and retarded the throttles to idle passing about 15ft above ground level. After lowering the nose wheel to the runway, Litavniks raised the flaps to position 20 and reset the pitch trim in preparation for the go portion of our touch and go. Litavniks called "rotate" at kt, our previous approach target speed.
With the landing gear retracted and safely on a crosswind leg for a visual circuit, Litavniks rapidly pulled the right engine to "idle", to simulate an engine failure.
The CRJ's rudder authority is increased in the event of engine failure, and referencing the flight control page on the multifunction display confirmed the FBW system was working as advertised. Less than 10kg of pedal force was needed to maintain co-ordinated flight at pattern altitude.
Rudder trim was more than sufficient to zero out pedal forces, but I elected to fly the approach and landing with rudder trim centred. The simulated single-engine approach and full-stop landing was flown with flaps set to I found the FBW rudder allowed me to maintain co-ordinated flight on final approach, as I used the left engine to maintain a target speed of kt.
As with the first approach, I started a flare at about 30ft above ground level. I centred the rudders as I reduced power on the good engine passing 20ft above ground level. Just before touchdown, I slightly reduced yoke back-pressure and the CRJ settled down nicely on the runway. With the nosewheel on the runway centreline, I used reverse thrust on both engines and moderate wheel braking to sharply slow the aircraft to a stop. Bombardier lists a landing field length of 1,m, a believable number given the short ground roll I observed for the 29,kg test aircraft.
During the flight we sampled a number of the events we had undergone in the CRJ Aside from gaining a better feel for the CRJ family of aircraft, I was also able to subjectively compare the FBW rudder to the conventional one. In all sampled flight regimes, aircraft responses in the lateral directional axes roll and yaw were similar. Had I not known of the two different control schemes, my brief flights in the CRJ and CRJ would not have alerted me to the fact.
It was my first exposure to the cockpit of a CRJ, other than the several times I had ridden on cockpit jump seats. I stated then that the CRJ blurred the distinction between regional and mainline jet and, in fact, could be considered a mainline jet.
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