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Aviation History
2001
2001 - 0457.PDF
LilMUCOPTmi VECLiMOLOQY gently lowered the lever, no rush. I asked for a repeat demonstration to do a more accurate count. After six seconds, at a rotor speed of 360RPM, Olson gendy lowered the lever, die nose pitching slighdy down and the NR recov ered to witliin normal limits. The normal min imum RPM limit, power off, is 390. Others should not try this themselves, but always observe die minimum of 390RPM. I was flyingwidi Schweizer's chief test pilot, who was involved from die beginning in die 3 3 3 's devel opment and in testing to establish die limits and a buffer zone. But it is comforting to know diat, if a pilot is really slow to apprehend what is hap pening in die event of a sudden loss of power, he will probably survive. The low-NR audio warn ing should eventually wake him up. EXCELLENT VISIBILITY We diverted to an unmanned airstrip and I car ried out a steep approach to a spot on die run way. It was accurate, arriving over the spot, but untidy. Olson said we were downwind. I did anodier into wind and was happy. The forward and downward visibility so important in such a manoeuvre was excellent. Likewise, in a vertical climb to 100ft and back. The 333 would be excellent for vertical reference operations where the pilot leans over the side to see the load carried beneath the helicopter on a long line. We then did a number of autorotations, power recoveries to the hover and engine off landings to die runway. Each was initiated by a throttle chop. Astraight-in autorotation at 60kt showed a rate of descent (RoD) of 1,700ft/min. This is higher than the published 1,400ft/min and was due, said Olson, to us flying at 60kt instead of die minimum RoD speed of 52kt, as well as to our lighter weight. The flare had bite, increasing the NRslowing the rate of descent and giving us time to level and dien restore the power while coming to the hover. Because die engine is downrated and die rotor is light, the response is immediate—sim ilar or better to that of a piston-powered heli copter. This is an excellent characteristic for a training aircraft. We then did anodier autorota tion, this time engine-off to the ground. There was plenty of time at the bottom to level, then judge when to pull in die collective to soften die landing. We did another at the autorotation VNTE of 90kt. The rate of descent was 2,900ft/min — a quick way to get down in a hurry. A zero airspeed autorotation gave 2,000ft/min and we took 500ft to get back to 60kt. So diis certifies the top of die height- velocity curve of 500ft. A 360° autorotation at 45° of bank gave us 3,000ft/min and we lost 1,000ft. Throughout these manoeuvres, con trol of NR was easy and, quite frankly, best left alone. You can easily get into pilot-induced NR fluctuations by overcontrolling light rotors The helicbpter is good at landing on a slope. The limits arean impressive 15° for sideways landings and 10° for nose up/down. We tried all four directions. y , Derived from the Hughes 269, the Schweizer 333 has evolved a distinctive appearance Finally I invited Olsen to dirow the 333 around. He did some impressive wing-overs at low level and rapid turn reversals at high speed, well below die treetops nearby. This demonstrated once again the aircraft's agility and control response. CRISP HANDLING Pilots will appreciate the crisp handling with low stick forces, the stability and forgiving characteristics of the Schweizer 333. Other goodpoints are the many safety features, engine power available, rapid acceleration times and all-rbund visibility. •: But pilots may wish the main gearbox allowed more of the engine power to be used. The slight side-to-side yawing might become annoying on a long trip, although I soon learned to disregard it. It would be an advantage sometimes to be able to see die skid gear when landing. And pilots will not appreciate having to learn all the torque and odier limit figures. Operators will appreciate the helicopter's multi-purpose flexibility, good payload and low acquisition and running costs. The 333's inher ent safety features and reliability are also likely to impress them. Technicians will welcome die helicopter's simplicity and low ratio of mainte nance hours to flying hours. Accessibility has been an important design feature. Passengers will enjoy the visibility, comfort, smooth ride and low noise, but they may wish for more bag gage space. People on the ground should appre ciate the Schweizer 333's low noise signature. • K'iltVi^^i^Hii'tHli^iI'lZf'' Length overall Main rotor diameter Height overall Powerplant (R-R 250-C20W) take-off 6.8m 8.39m 3.34m 185kW Operating weight empty Fuel (usable capacity) Useful load Maximum endurance (4,000ft, std day) 549kg 227litres 608kg 4.19h Max continuous 170kW Range (4,000ft, std day) 590km "FLIGHT INTERNATIONAL 6 - 12 February 2001 41
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