A Real Aeroplane in Miniature: the Druine Turbulent
IN Great Britain the skies can hardly be said to be filled with aeroplanes of any sort, and certainly they are not crammed to capacity with small ones. Even the majority of private and club aircraft are versions or conversions of military types, so it is a pleasant change to hear of an essentially light aeroplane that is not only available on the public market, but actually in production in this country ! By this, of course, we refer to the diminutive Druine Turbulent.
Designed in France and originally intended for home construction amateurs in that country, the Turbulent first made itself known here in physical form early in 1936, when F-PHFR made a tour of several aerodromes, and in it many of us were fortunate enough to try our hands at a delightfully personal style of aviating. Although this visit created considerable interest at the time, more recently this has been stimulated into practical enthusiasm, for Rollason Aircraft and Engines Ltd., of Croydon (whose managing director, Norman Jones. is Chairman of the increasingly-active Tiger Club), laid plans for an initial batch of six to be built in their own works. Although the final decision to produce was made as recently as May of last year, the company wasted little time for G-APBZ, the prototype (if the word can be used with a dear conscience), flew on January 1st last and three months later to the day a second machine, G-APIZ, took the air for the first time. By the time this appears in print a third Rollason-built Turbulent should have left the line.
As most readers will know, the Turbulent is a single-seater, and it uses for power an Arden conversion of the well-known and rugged Volkswagen car engine. The normal French version has a tailwheel and brakes, but for lightness, simplicity and economy, Rollasons have omitted these luxuries, substituting a skid and smaller wheels that are perfectly adequate on smooth grass aerodromes, but which create problems on runways (with their attendant cross-winds) and on very rough ground. Nevertheless, ground manoeuvring is tolerably easy and even on a relatively tricky aerodrome like Elstree it is possible to wander where one wishes except in conditions of very high winds.
Equipment is sensibly reduced to the minimum essential for the style of flying for which the aeroplane is intended, and as there is no trimmer and no flaps the pre-take-off cheeks can have the ” s ” omitted, and all one needs to do is ensure that the fuel is on. The take-off itself is straightforward, but there is no kick in the back, for although the engine thinks nothing of 3.000 r.p.m, it produces only 30 b.h.p., and the propeller on C-APBZ seems to give a reduced acceleration and climb compared with the performance of the French machine tried two years earlier. Nevertheless, there is no question of lingering: the tail comes up and the rudder becomes effective almost immediately, although I must confess a tendency to over control with my feet, which I kept waggling quite unnecessarily throughout the ground run. Although the unstick is not very decisive, this is of little consequence, for the machine will ease itself into the air when ready, and this may well prove a blessing when letting inexperienced pilots loose for the first time. There can be no simpler briefing to give a pupil than telling himto push the throttle open and just keep the thing straight until it’s in the air !
Quite naturally the climb is not startling, and although I have made no attempt at a time-to-height check (I had no intention of writing this when flying either F-PHFR or G-APBZ), I ant perfectly prepared to accept the designer’s figure of about 485 f.p.m. as a realistic claim. Although quite capable of serious cross-country flying, the Turbulent is the type of aeroplane that it likely to spend the majority of its life at the lower levels and it should hardly ever need to climb much over 2 or 3.000 feet.
In normal flight the controls are very light and positively effective, although their very lightness creates a tendency to over-control which I found particularly apparent with the ailerons. Although the speed range is not very great, I felt a little disappointed that there should be only a very slight increase in stiffness or response with increased in airspeed, and, of course, vice versa, which means that a pupil could approach the stall unintentionally without any foolproof method of warning. However, when the stall arrives, it is innocuous enough, and as the A.S.I. reads under 30 m.p.h. when it happens, there should he little danger of this state of affairs arising as a regular habit.
The Turbulent is not cleared for aerobatics, although in France the type has been looped and rolled quite happily, but it is essentially a sporting aeroplane and there is plenty of enjoyment to be had from fast-reverse steep turns, wingovers and other similarly law-abiding occupations. Although quite a respectable rate of turn can be maintained with accurate handling, and the amount of sky used is negligible, there is a marked tendency for the airspeed to decrease as soon as any loading is imposed, and the hard-working little power unit is pushed to make thrust a match for drag.
In cruising flight the airspeed settles at a figure comfortably over the 70 mark, while a protracted run at full power adds just under a score to this. Bumpy weather makes the needle leap frantically almost from one end off the scale to the other, and speed decreases rapidly as soon as the nose is raised even slightly above the horizontal. I found this feature perhaps the only really unsatisfactory characteristic of the type, for low down in rough conditions, especially when endeavouring to pull away from a downdraught, a pupil could easily run out of airspeed and suffer the inevitable consequences. This is a common failing with light clean aeroplanes that rely for their performance on their lines rather than the power available.
The approach to land holds in store no peculiarities and it seems to matter very little what speed one chooses for doing it. About 50 m.p.h. produces a satisfactory average figure, but very little round-out is needed as the ground angle is unusually flat. This makes the landing itself complete simplicity, but I found a strong inclination to hold-off too enthusiastically and touch tail-skid first. During the ensuing run in anything but a strong crosswind there is little difficulty in keeping straight right down to a standstill.
Already about thirty pilots of widely differing experiences have flown the first Rollason Turbulent, and without exception they all seem to have enjoyed it. Although my criticism makes reference to a number of weaknesses, this is intended in no way to detract from the enjoyment that can be derived from flying this delightful little aeroplane, for I revelled in every minute of it, and only lack of space prevents my giving a more detailed appraisal.
The Turbident is currently available for entirely home construction, for building from a kit of parts or, for about £1,000 as a fly-away factory-built aeroplane. It should prove useful for small groups who wish to operate something really economical, for pilots wishing to amass quantities of hours to qualify for higher licences, or for purely sporting purposes. One day, perhaps, we shall see the National Air Races incorporating a one-class event for the type. Unfortunately, it is not eligible for a full British Certificate of Airworthiness but operates on at Permit to Fly, and this, alas, prevents its use on a hire-and-reward basis, which means that it is of no use to commercially-run flying clubs. Nevertheless, there are hopes that this problem may be overcome before long and in the meantime we cant hope that more people will fly more hours, more cheaply, and more enjoyably than they have been able to fly until now. – D.F. OGILVY