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Aviation History
2004
2004-09 - 1258.PDF
FARNBORO' I N T E R N A T IA42 Twin 1 9 s, with a viewable area 220mm wide .60mm deep, are identical but with ing functions for the menu buttons ; the side and base of each screen. I :st wearing gloves - the glareshield lang is not that great and at some s the screen was not easy to read if was any finger grease contamination, rwise the flight and navigation infor- m was easy to read. I found the mov- lap on the right-hand screen useful, th screens can show the same basic mation, or flight data can be shown ie left display and navigation on the I feel the vertical tape presentation of ;ed, altitude and vertical speed will re careful attention when converting an aircraft with dial-type instru- s. The G1000 offers an incredible of features, but it is an advanced dis- and flight-management system com- i and pilots will need almost as much ing on this as the aircraft itself. ectional stability itudinal and lateral/directional stabil- as checked next around a trim speed Okt and level-flight power with 50% on each engine. At 190kt, it took only t 3kg forward stick force to hold the tor out-of-trim force. This means you ot constantly trimming when acceler- . The phugoid was well damped and, a period of around 60s, would not be isive in cruise flight. The short-period 5 showed the aircraft was quick to md to stick input and well damped. s, flaps up, up to 3.5g were made in directions with no stick-force discon- ties and no buffet. iral stability was neutral or slightly ive, which is a good safety feature for entive pilots. Dutch roll was quickly xd within half a cycle without the for pilot input. Roll rates at 140kt full stick deflection but without rud- rere about 357s and about 50°/s when rudder was added. At full rudder ction, at 140kt, the opposite bank : was 30°, showing the aircraft has sideforce characteristics to kick off during a crosswind landing, leron-only turns, using full lateral stick, ted in an immediate, opposite heading ge of about 5° due to adverse yaw, but leutralised by the aircraft's directional lity after 2-3s. In rudder-only turns ; full pedal deflection, the aircraft d in the direction of the applied rudder 3-4s later rolled positively in the same tion at about 10-15°/s. iroughout the flight I found the DA42 "lively" directionally and did my best e the rudder to counteract the slip. But the only slip indicator is a 1 x 5mm grey bar that sits horizontally under the small grey bank-angle indicator, on a blue back ground, at the top of the horizon display on the G1000 screen. Given the slip indica tor's importance, it did not exactly stand out. I hope Diamond will consider fitting a chunky, old-fashioned "spirit level" type slip ball in the production aircraft. Unaccelerated stalls were evaluated with zero, take-off and landing flap deflection, all at idle power, and were probably the most docile of any aircraft I can remember. Controls in all axes were effective approaching and in the stall. The warning horn sounded 5-7kt above stall, which was indicated by increasing airframe buffet, dis tinct nose drop of 5-10° and vertical descent of about 2-300ft/min. There was no wing drop. Stall flaps "up" was around 65kt, flaps "take-off" 55kt and flaps "land ing" 45kt. I tried a stall in approach config uration, with take-off flaps and 30% engine load, but with the nose about 20° above the horizon and distinct airframe buffet, horn sounding and virtually no sink rate, I gave up. I believe any pilot or student would have to more than grossly mishandle the aircraft on approach to get it to stall. My final check was to assess the DA42's behaviour after a simulated engine failure at V2. I stabilised at 80kt, full power, nose about 10° above the horizon and rapidly brought the left-hand power lever back to idle (the propeller was not autofeathered). Swing towards the dead engine was instan taneous, but could be held with rudder, although the forces were high at 80kg. Once gear was retracted, these reduced to about 50kg, with the nose gear doors no longer acting as a forward fin. With auto- feather, these forces would reduce even fur ther, as they would with rudder trim if it was not so difficult to grip. Final check On the return leg, at 75% engine load, in level flight at 165kt and 5,000ft, fuel con sumption was 21 litres/h (5.5 USgal/h) per engine, with the computer showing a 1,110km (600nm) range and 4h endurance. In a long-range cruise at 50% engine load and 140kt, fuel flow was 14 litres/h, and cal culated range 1,480km and endurance 6h. We dived back towards the circuit at 190kt. There is no overspeed warning but the airspeed tape shows a red/white "bar ber's pole". Another small niggle - at power settings below about 30% load, the aircraft has a non-cancelling gear-up warning horn, which sounded for the whole high-speed descent until we were in the circuit and power was increased on the downwind leg. I suggest the warning be linked to flap posi tion so that if the gear is not down when the first stage of flap is set on the approach, then the gear-up warning sounds. Various normal and flapless circuits and roller landings were flown on to runway 10, with the crosswind still about 10-15kt from the right on touchdown. They were easy to fly. The low longitudinal static-stability gra dient combined with the vertical-speed tape display meant I had to pay particular atten tion to speed control. Initially, my cross- wind landings were untidy, with too much TECHNICAL DESCRIPTION Inside the Diamond The DA42 is a major development of Diamond's DA40 piston single. It uses the same wing sections for the outer panels, but they are finished at the tip with a pronounced 800mm (30in)-long tapering and near-vertical winglet. The cabin, from rear bulkhead to instrument panel, has the same dimensions as the DA40's and fea tures the same forward-hinged clamshell canopy and side-opening (left side) cabin door for access to the rear seats. The rear fuselage has a similar T-tail, but with the addition of a fillet between the boom and fin and a dorsal fin of increased area. Ailerons, rudder, elevator and wing flaps are constructed from a carbonfi- bre/glassfibre sandwich. Ailerons, elevator and flaps are operated via control rods, with cables for the rud der. All flight controls are manual, but the flaps are electrically driven and controlled by a three-position switch in the cockpit. "Simple flaps" span the first two-thirds of each outer wing panel and there are "split flaps" under the wing sections between the fuse lage and engine nacelles. Elevator and rudder forces are trimmed via a cable-operated tab using separate trim wheels or, for the elevator, a dou ble-pole trim switch on the control stick. The left-hand aileron has a fixed trim tab that can only be adjusted manually on the ground. The undercarriage is hydraulically operated with spring assistance, and hydraulic pressure is provided by an electrical pump. The nosewheel retracts forwards and the main gear CONTINUED ON P90 flightinternational.com FLIGHT INTERNATIONAL 13-19 JULY 2004 89
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