By Ronald A. Keith

DESIGNED for military and civilian ab initio flight training, the D. H. Chipmunk is a slick and sturdy successor to the venerable Tiger Moth. The many thousands of Tiger graduates would discover only slight family resemblances in this newest member of the D. H. family. For in creating the Chipmunk, de Havilland Aircraft of Canada have tapped the rich supply of wartime training experience. The result is a safe and rugged aircraft with the lively virtues which elementary instructors have hitherto encountered only in their wishful thinking. Yet it has no corresponding vice that we could discover in several hours of testing the plane under a variety of conditions.

        Seated in the front, master cockpit, the pilot is first impressed with the almost 360 horizontal visibility which contrasts so satisfactorily with the biplane trainers. The single-piece plexiglas canopy slides easily fore and aft on three rails, one on either side of the fuselage, the third on top of the fuselage behind the rear cockpit. A spring-loaded plunger, operated by a twist lever overhead, engages in four positions on the base plate of the rear rail, permitting the hood to be locked partially open.

        Modifications call for installing a break out panel, meanwhile take-offs and landings are made with the canopy fully open. The crash pylon is noticeably absent from the conventional position between the cockpits. Instead, it is integral with the canopy structure, a much neater arrangement.

        For emergency escape in flight there is a small scoop in the top of the canopy. With the turn of a handle, this scoop springs open thus enabling quick opening of the canopy, especially at speeds over 120 m.p.h. The cockpit is spacious and orderly. The fuel cock is a sliding knob centred on the floor. Fully forward is ON.

        There are two sets of ignition switches, one on the master instrument panel, the other, as in the Tiger, on the fuselage section between the cockpits. Either set of switches 0FF breaks the circuit.

        Starting procedure is conventional. With switches OFF and brakes the mechanic pulls the carburetor flooder control, on the port side the engine, and operates the pump hand levers until fuel rums out of the overflow vent at the bottom of the engine. The engine is turned over with at least three pull-throughs. Then, with all switches ON and throttle cracked a half inch, the prop is swung through compression.

        A hand fire extinguisher is clamped in the front cockpit, The elevator trim wheel is on the left wall at knee level operating in the logical sense, forward nose-down. Above it is the throttle quadrant, similar to the Tiger's, with a mixture lever which moves automatically to full rich when the throttle is closed.

        The brake lever also is on the port side, under the instrument panel. It is locked in any position by a ratchet as in the Tiger. The hydraulic brakes are differential. Application of full rudder applies partial brake to the corresponding wheel. This brake pressure is increased by use of the hand lever.

        The flap control is a lever on the starboard side of the cockpit with a hand-pressure trigger to release the retaining pawl. This trigger is protected against accidental release by a guard. There are three positions UP (lever fully forward); 15 (flap (half-way back); and 30 flap (fully back); Flap indication is direct as the position can be seen from both cockpit. The two fuel tanks are in the wing roots with external gauges directly visible from both cockpits. Gauge faces are calibrated in two scales, one indicating for the three-point attitude the other to be read when in level flight position. For taxiing, the hand brake lever is about four notches back to obtain differential application with rudder pedals. It might be argued that brake lever should be on the starboard side, in which case it could be operated with the right hand while left remained on the throttle. Of this procedure would involve without the stick held full, which is not recommended on ground. At any rate, we found the manipulation of throttle and brake levers rather awkward, particularly in a strong wind. The Tiger Moth type of brake lever is not, in our opinion, the best imaginable.

        The wide undercarriage span coupled with differential braking and higher wing loading makes the Chipmunk much more manageable in high winds and gusts than most elementary types. We flew without difficulty on one afternoon when most of the other types in the vicinity were grounded by a gusty wind up to 45 m.p.h.

Handling Characteristics

        Although visibility for taxiing is vastly improved in the Chipmunk, It is still necessary to zig zag for a full view of the runway, even from the cockpit, more so from the rear.It was not until we started doing a few circuits and landings that the most remarkable improvement of the Chipmunk, compared with previous elementary trainers, became apparent. The rapid take-off and climb (900 f.p.m. at 80 m.p.h.), the 124 m.p.h. cruising speed and the steep flapped approach added up to a surprisingly quick circuit. The company claims that at lest 20% more landings per hour can be achieved in Chipmunk instruction than with the wartime trainers.)

        In normal flight, the Chipmunk exceptionally light on the controls we found that it could be trimmed to fly hands off indefinitely in calm air. Stalls are normal although the nose drop is quite, sharp with flaps down while the steep turn is preceded by considerable shuddering.

        In spins, the Chipmunk starts with relatively slow rotation for the first turn with the nose down steeply. Then the rotation speeds up for two turns before settling down to a constant rate of angle of about 45. When full opposite rudder is followed by easing the column forward, the aircraft recovers in one-and-a-half turns at most, assuming a quite steep diving position.

        Solo spinning has to be done from the rear cockpit, otherwise the centre of gravity is too far forward to achieve a good spin unless ballast is carried in the rear cockpit.

        We found the Chipmunk to be remarkably nimble in aerobatics. The slow roll can be accomplished nicely even at cruising speed although 130 m.p.h.is recommended. Flying solo and with an entry speed of 150 m.p.h., it is possible to gain 500 feet or so in a roll off the top of a loop. A smooth loop can be performed with an initial speed of 140 m.p.h. Thus a further pronounced advantage of this trainer over its predecessors becomes apparent Many hours of student and instructor time can be saved because, with this aircraft, it is no longer necessary to waste time with those long and boring climbs to regain altitude lost in rolls and spins.

        Considerable variation in approach angle is obtained with flaps. The glide is quite flat without flaps. With full flaps the nose is well down and the glide is steep enough for introducing the students to approach characteristics of more advanced aircraft.

        The Chipmunk is powered with the Gypsy Major four cylinder inverted in-line engine which delivers 140 h.p at 2,400 r.p.m. at sea level. Consumption is 6.4 gal./hr. at economical cruising.

        Initial cost of the aircraft is $7,500. The company has estimated that operating cost for 500 hours a year is $6.15 per hour while for a 1,000-hour year the cost is $4.65 per hour. These calculations include engine replacement, 10-year depreciation, insurance(10%), maintenance, fuel and oil. Per mile costs, as above, amount to 5 cents, and 3.8 cents respectively.