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Aviation History
1931
1931 - 1230.PDF
FLIGHT, NOVEMBER 20, 1981 " In both cases the results were very similar to those with the deepenedfighter. Spins at high incidence could not be obtained and recoveries were rapidly effected. The model with increased fin area was slightlysuperior to the other, but not quite as good as the deepened fighter both as regards rate of spin and rate of recovery." A similar experiment was carried out with a l/20th scale model of the Bristol Fighter to compare the effectiveness of an increase in rudderarea of 85 per cent, in combination with several fin arrangements, with that obtainable by raising the tailplane towards th e top of the standardrudder." The types of modified tail tested were:—(A) A higherfin and rudder than the standard ; (B) a fin and rudder arrangement in which the rudder axis was sloped forward ;(C) a rudder in which the maximum chord was placed low ; (D) an inclined rudder, similar to (B), but on adeepened fuselage ; (E) tailplane and elevator placed at top of rudder, but on ordinary fuselage ; and (F) tailplaneand elevator placed at top of rudder on a deepened fuselage. " The additional rudder area," the paper continues," was so disposed as to avoid to some extent the screen- ing effects of the tailplane and elevators at high angles ofincidence. Under test all units produced recoveries from a standard fiat spin except the normal tail unit and thefirst of the modified ones. The order of merit as deduced from the number of turns required to do so was (F), (E),(D), (B), (C), (A). It was noticed that the rate of turn of the steady spin was lower than that obtained withthe standard tail unit for each of the modified units." Comparison showed that the deepened fuselage was moreeffective than a wide one surmounted by a fin. It is con- cluded that the experiment as a whole demonstrated thefutility of providing a large rudder situated immediately behind and above the tailplane as a means of ensuringrecovery from spins at high incidence. A relatively small rudder can produce rapid recoveries from a flat spin ifthe tailplane is raised to the top of the fin. Conclusions Among the conclusions reached by the authors we quotethe following: — " The rudder is by far the most effective control for the purpose of•"* recovery from an established spin. "~ " Ailerons are not likely to effect recovery by virtue of the rolling" couple they can produce: their influence in stopping or augmenting the spin will be governed rather by the yawing moment which they exert- (body axis). " Powerful elevators will probably, in general, effect recovery from aspin ; but the initial effect of setting elevators against the spin will always be to tend to set up another and faster spin. " ft is not clear that reversal of elevators invariably assists recoveryduring the flat spin stage, and some delay in moving the elevators down may conceivably help in certain circumstances." The following are beneficial both as tending to prevent the develop- ment of the flat spin and the falling off in rudder power while spinning :—Raising the tailplane. Sweeping back the tailplane or moving it aft of the fin and rudder. Positive dihedral angle on tailplane (bent up-wards). Peepening the body, " Scaplam; floats generally tend in their effects towards making the5pin natter and slower. Their chief effect is on pitching moment, producing a large positive moment and reducing the elevator controlin the spin. They also produce some positive yawing moment at flat spinning angles and seem to reduce rudder control." Differential ailerons, while probably of some use in recovery if the spin does not become flat, are apparently of little use in a really flatspin. " Floating ailerons may be expected to effect but little improvementas regards recovery from a spin. " Spinning calculations, based chiefly on rolling balance tests of acomplete model rotated about the wind axis through the centre of gravity and a knowledge of the moments of inertia, appear to give a fan-approximation to the spinning characteristics of the aeroplane and a rough indication as to its quality of recovery." Before the discussion started, Mr. A. V. Stephens gavea very interesting demonstration with a small model of the vertical wind-tunnel which is now being built at Farn-borough. This model, which was a many-sided vertical glass case of about 2 ft. diameter, had a fan at the topdrawing the air upwards through it. Small balsa-wood models of various types of aircraft were used and placedon a vertical pivot on the floor of the tunnel, with the pivot arranged so that the models rotated approximatelyabout the spinning axis. As soon as the fan was turned on and the air-stream reached sufficient force, these modelsrose up and spun most realistically. According to their loading and type, the attitude of spin varied, some beingvery flat and stable, some very steep and slow, while others only maintained the spin for a few revolutionsbefore coming out to one side or the other. Such a demonstration undoubtedly showed the pathalong which investigations in the full-sized tunnel could be led, and would appear to point to the fact that farmore could be learnt from such experiments than from filming spinning models as they fall from the roof of ahigh building, such as the balloon shed previously used for this purpose. <•> m:-: ••• CCEEESPCNDENCE The Editor does not hold himself responsible for opinions expressed by correspondents. The names and addresses ofthe writers, not necessarily for publication, must in all cases accompany letters intended for insertion in these columns. j _ OUR AIRSHIP POLICY [2777] Our airship policy being a very polemical one,I wish to join the fray and enter my plea forthwith for the retention of R.100, and the construction of more rigidairships. I have heard with much alarm that R.100 is for sale.One can only hope that it is but another rumour, as such a step would put us in the same position as those nationsindifferent or apathetic to high-speed flight. All knowledge gained about airships will be lost, and the effort, later, toretrieve our position will be a costly one. In my humble opinion an airship instruction schoolanalogous to the High-Speed Flight should be maintained as a distinct and complete part of the R.A.F. It wouldnot be a burden to the Exchequer, and in the near future would prove a better plan than the abandonment of ourairship programme. It is hard to believe that our financial position is sodesperate that a tmall sum could not be set apart for further test flights with R.100. Later, passenger tripswould make her self-supporting. With such shining examples of airships before us as theGraf Zeppelin and the Los Angeles, which have successfully completed innumerable flights, the former in Arctic andTropic temperatures, it is difficult to comprehend our stand. The new Akron has passed her tests and recently carriedtne record number of 207 passengers on a ten-hour cruise. Germany and the United States are both building biggerairships and will have a fleet of lighter-than-air craft in a few years. We must realise the fact, and it must be most forciblybrought home to the powers concerned, that the work must gq^on. Airships are absolutely indispensable to us and our EmPire- JOSEPH RALPH. New York, U.S.A.,November 6, 1931. POBJOY ENGINE PARTS [2778] Having read with interest your article onpage 1125 of this week's issue, headed " Butler's Flight to Australia," we would like to make the following com-ment on a portion of same, to which amendment we shall be glad if you will kindly give due prominence in your JOURNAL at an early date. We refer to the 11th paragraph, wherein you state:"... a large number of the parts for this engine, includ- ing the cylinder barrels, heads and pistons, etc., aremanufactured by the Mollart Engineering Co., of Queen's Road, Thames Ditton," whereas the cylinders from theactual castings, with the exception of the final honing and fitting of heads, were dealt throughout at these works. Other items we also machined from the raw material forthe same engine comprised: —Complete crankcases, pumps, oil filter and tank, valve caps, big-end and other bushes,magneto brackets, breathers, starter gland assemblies, tappet guides, etc. A.B.C. MOTORS, LTD., T. A. DENNIS. Walton-on-Thames, Surrey. November 13, 1931. 1160
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