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Aviation History
1957
1957 - 0790.PDF
796 FLIGHT The Dornier Do 27 (Ly- coming GO-480 engine). Its flying characteristics are ". . . as distinctive as its appearance." "Flight" photograph COSMOPOLITAN QUARTET... with a very steep descent indeed. The pilot called for full flap,and the increased drag made me hold on to a support as I knelt behind the jump seat. We rolled off bank and touched downat 94 m.p.h. and ran for about 400 yd, using plenty of the very assertive, toe-operated powered wheel-brakes. I thought this landing, and a similar one we made on anotherflight, showed particularly well the characteristics of the Avia 14. It really is designed for short rough fields and could go into verysmall spaces. It does not pretend to be a Convairliner, although it looks very like one. I would compare it rather to a muchmodernized, thoroughly efficient, oversized Anson. Galley, toilet, full blind-flying and radio-navigation equipment, in addi-tion to a very reasonable performance and excellent handling, make the Avia 14 a most useful machine for use in relativelyundeveloped areas. This particular example was going to China immediately after the Paris show.The Czech pilot's name is, I think, well worth remembering. It is Kaustik. Dornier Do 27. On the first Sunday of the show, watchingHerr Schafer give his amazing demonstration in the Dormer, I felt a strong urge to make closer acquaintance with this aircraft.Schafer took off in the strong wind and climbed pretty well vertically up to about 1,000ft. Flicking over almost on to hisback, he roared down again and went through a series of manoeuvres which demonstrated the amazing low-speed handlingqualities of the aircraft. He ended his demonstration with a landing with the propeller stopped, drifting down very slowly,with all the flappery hanging down, and wagging the Dornier's tail 30 or 40 degrees to each side. Rumour had it that he wasalways on the look-out for thermals to soar in. With three passengers the Do 27's performance seemed little affected. I first talked to Herr Klaudius Dornier, the eldest son of thebusiness, and heard what his company is doing. To date some 25 Do 27s have been built, some of them "Bs" with dual control,but mostly "As" with single control for the German army. Production is building up to 15 a month at the end of thisyear and the price is between 115,000 and 120,000 Deutschemarks (about £10,000). The engine is a Lycoming 270 h.p. with con-stant speed propeller. Since its Spanish days the airframe has been "productionized" and the fuselage contour has been slightlyaltered. The whole airframe is built up round a strong floor- structure which carries the single main frame holding the torsion-box wing and the engine. A single post in the middle of the sharply swept windscreen serves as a crash pylon. Both wind-screen panels are themselves upward-opening doors, to which one climbs over the wheels and on a footstep on the undercarriageleg, using the door-support strut as a convenient handle. The monocoque tail is attached to the floor and anchored bytwo built-up beams from the main wing frame. The cabin itself is, therefore, very little encumbered by structure and twolarge rectangular glazed side-doors give easy access. Four passengers, or two NATO standard-size stretchers, can be carriedcomfortably in this space. (The Czech Agricolta, which is of about the same size, carries two of the smaller stretchers and itsperformance is not quite so impressive as that of the Dornier.) The Do 27 has a top speed of 156 m.p.h., cruising speed of125 m.p.h. on 60 per cent power, and a cabin, aft of the pilots' seats, 6ft lOin long, 4ft 3in wide and 4ft 5in high—a volumeof 124 cu ft. The minimum speed is given as 35 m.p.h. Herr Dornier said the machine was particularly designed notfor slow flying but for safe manoeuvring at very low speeds; and Schafer really showed me in no uncertain way how successfulthe designers have been in their work. Indoctrination started with that staggering take-off and almost vertical climb—at justover 40 kt indicated. We sailed up at l,000ft/min with the engine noisily hauling us straight into the clear blue sky. Thoughthe cowling slightly obstructed forward vision on the ground, it was not obtrusive in the air; visibility sideways, forwards andrearwards (through the glazed roof) was good, and downwards it was virtually uninterrupted—so much so that at times it gaveme a slight feeling of vertigo. A novel feature is that the back-rest of the co-pilot's seatswivels. The pan slides backwards and forwards, but the rudder pedals are not adjustable. Steering on the ground is by toe-brakes, but in later aircraft the tailwheel will be steerable. After take-off we continued out over the green fields east of Le Bourget.I took over and got the feel of things, finding the machine very pleasantly stable at cruising speeds and extremely steady andmanageable at very low indicated speeds. Then Schafer took it, cut the engine and hauled the machine into an almost verticalclimb. Looking over at me, he said he could pull the stick right back to the stop; and as we went up at a horrifying angle, with thespeed firmly dropping off, he banged it there to show me. I was ready to say my prayers when the aircraft finally seemed set fora tail-slide, but . . . very slowly . . . the nose dropped over for- wards and we fell into a steep dive. There was no buffet andno wing-drop—in fact, no sign of protest from anything or anyone but myself. We then did it again—several times. Itried to stall it out of a steep turn. When I thought we must be close to it, Schafer pulled on full flap with the great handlebetween the seats and the turn tightened up sharply. Again he hauled the stick back, but there was not a tremor from the air-craft. The machine can, in fact, be flown slowly enough, straight and level, to stop the propeller—I saw the pilot do it. There are three flap settings: 12, 26 and 42 degrees. Schafer'sfavourite was 26 deg, and he applied it mostly at the top of that almost vertical climb before winging over for another look atsomething he had just passed. He could get 1,000 ft/min climb at 30 kt I.A.S. and swing the tail backwards and forwards as ifhe were trying to see round the further side of the engine cowling. He spotted some farm-hands working in a hayfield, plonked theaircraft down right next to them, and took off again after a total run of less than 100 yd. We found a small airfield and put on areal tail-swinging and zooming demonstration for a group of French people who came running out of the hangars and offices. I took over again for the cruise back to Le Bourget. Horizontaltail trim is effected by varying the incidence of the tailplane with a very low geared (but very large) trim-wheel. Havingflown the Otter, which has a similar system, I thought of setting the tailplane at about half forward position, about two degrees,and throttling back and extending flaps to see whether there was much elevator control left. There was enough for normal control,but probably not enough for landing. With all trimming arrange- ments of this kind it is important to see that stick forces aretrimmed out for the landing, so that the elevator will not be over- powered by the tailplane at the critical round-out phase. In addi-tion to very effectively cancelling trim changes caused by the high-lift system and powerful engine, a variable-incidence tail-plane can cope with a very wide range of e.g., allowing rela- tively careless loading of the cabin. Schafer showed me the standard approach method for theDornier 27. The engine is throttled back and flap extended. (Ailerons, incidentally, are in two sections on each side, the innerportion drooping progressively as the flaps come down.) The approach is made in a glide at 45 kt I.A.S., with the nose almostabove the horizon. If the tail is then swished from side to side, the visibility is greatly increased and the rate of descent will buildup to 1,000 ft/min. There is plenty of aileron control and the machine can be lowered down on to a given spot with a burst ofthrottle to cushiorr the impact. There is a distinct feeling that
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