Rolls-Royce Engined DC-4M Stepped Up in Weight and Accommodation : Impressions in the Air

        The first Canadair Four (DC-4M-4) is now coming through the shops and is expected to be flying in July of this year. Rate of production, it is hoped, will rise very sharply towards the end of 1947 and a figure of fifteen per month is mentioned as a possibility. In the accompanying table are set out the main weights and performances, all of which appear more favourable than the equivalent figures for the DC-4M-1. Seating capacity is increased by four – from 36 to 40 – gross weight goes up by 2,000 lb to 80,000 lb and the max. landing weight from 63,500 lb to 68,000 lb. In addition, the cabin will be pressurized on the DC-6 system.

        Power Plants will still be Rolls-Royce Merlins – the civil Mk 620 variety – which give 1,725 h.p. for take-off at 20 lb boost and a normal maximum output of 1, 285 h.p. For maximum cruising, up to 23,500 ft, 1,160 h.p. with 9 lb boost is taken out of each power unit.

        It will be remembered that the DC-4M was originally built as a transport aircraft for the Royal Canadian Air Force and six of these have been loaned to Trans-Canada Airlines to run ther transatlantic service between Montreal and London. Ten journeys each way per week are made. All six of these aircraft were fitted out by Canadair, Ltd., to T.C.A. specifications.

        Recently we had an opportunity of flying in one of the DC-4M-1S while it was being demonstrated by Capt. A. Lilly, Canadair’s chief test pilot, who has 6,000 hours airline piloting to his credit in addition to 4,000 hours test flying.

        At an all-up weight of 63,000 lb the aircraft left the ground after a run of only 13 seconds and climbed at more than 1,700 ft per min. Reaching 8,000 ft, one of the Merlins was stopped but the remaining three held the rate of climb at 1,500 ft per min. At 9,000 ft both port airscrews were feathered and, with the Merlins each running at 2,650 revs, a climb of 200 ft per min was still maintained. Finally a third engine was stopped and at that altitude, height was lost at the rate of only 150 ft per min. Capt. Lilly said that the DC-4M will hold its height on one Merlin, running at 2,850 r.p.m., at any altitude below 6,000 ft.

        Demonstrating the viceless stall under landing conditions, the wheels and flaps were lowered and the nose pulled up. A distinct tail buffeting could be felt as the A.S.I. fell to 80/82 m.p.h. At 75 m.p.h. the nose went down sharply but there was no tendency for a wing to drop. It is said that if a pilot is quick with the throttles no more than 20 ft need be lost in a stall.

        Level flight, at a normal cruise power, provides very pleasant travel. Speech between passengers can be made without straining either voice or ears. Hitherto, some criticism has been made of the noise intensity in the cabin of the M-1. A special type of exhaust manifold, designed by Canadair, has now replaced the stubs on the cabin side of each power egg and this has brought the sound level down to that of the DC-3. The exhaust batter on the cabin walls has quite disappeared. Rolls-Royce, Ltd. intend to do further development work on this exhaust manifold.

        Good piloting, together with the tricycle arrangement and the attitude which the DC4 take sup when the flaps are lowered, makes landing appear to be a very simple operation for a machine of its weight and speed. The end of the runway remains a steady picture in the pilot’s windscreen during the whole of the approach and only disappears underneath as the stick is pulled back for the hold-off. Even then the tail-up attitude of the Canadair Four ensures for the pilots a good field of vision, both forwards and downwards.

Flight, June 26 1947, p. 609-610