FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1933
1933 - 0610.PDF
FLIGHT, SEPTEMBER 21, 1933 AIRWORTHINESS AND COMMON SENSE By W. 0. Manning, F.R.Ae.S. In the article published in our issue of September 7,1933, Mr. Manning dealt with some of the effects which the increased load factors recently introduced may have on future aircraft design. In the following article he turns his attention to the subject of spinning, and makes the very telling point that an aeroplane which "flicks into a spin'" but will come out of it again in the prescribed number of turns will get its C. of A., whereas a machine, which may be very difficult to spin at all, may be refused a C. of A. because if it is forced into a spin it may take a half-turn more to come out. Which is likely to be the safer machine ? N the reference to my last contribution which the Editor did me the honour to make in the editorial column, he referred, very pertinently, to the large proportion of aircraft accidents which are due to the " human element," and which are usually recorded as being due to "an error of judgment on the part of the pilot." In this connection it is worth recalling a recent remark by Mr. C. R. Fairey, who, with his usual insight into these matters, pointed out that the aeroplane could be considered perfect when all accidents are due to the fault of the pilot. But there is one class of accident the responsibility for which must be shared between the aeroplane and the pilot, and which might be eliminated altogether if we knew enough about aeroplane design, I refer to the com mon case of a stall followed by a spin. It is quite easy to stall an aeroplane inadvertently. It has frequently happened that an inexperienced pilot has throttled down with the intention of landing on some field unknown to hirn, has his attention distracted by the problem of finding the best direction of approach, and allows his machine to lose flying speed. The next thing that happens is that one wing goes down and the machine goes into a spin. This is not in the least dangerous if he is at a sufficient height to enable him to recover, but if he is not, there is inevitably a bad crash. The really experienced pilot does not make this mistake; most of them have erred in this way early in their careers, have had the lesson rammed home by a narrow escape from a bad accident, and have developed their instinctive control of the aeroplane to the extent that they maintain adequate flying speed without thinking about it. The slightest suspicion of a control getting too soft and down goes the nose automatically. But this only comes with experience which the new pilot cannot hope to possess, so we still read occasionally of accidents reported as due to the pilot's error of judg ment, when what really happened was that the pilot made a simple mistake and the aeroplane did the rest. The perfect aeroplane for the ordinary civil pilot is one which will not spin at all, and the next best is one which can only be made to go into a spin with the utmost pos sible reluctance, possibly by control movements which no ordinary pilot is ever likely to use. Aeroplanes have been produced which even the most expert pilots have been unable to spin, and aeroplanes which spin only with great difficulty are not very uncom mon, and it is reasonable to expect that the regulations would encourage the production of machines of this sort. Actually, there are no regulations laid down in the con ditions for the issue of a certificate of airworthiness for an ordinary aeroplane which deal with this matter, though it is understood that the Test Depot carry out tests on spinning and report if the aeroplane is considered unsatis factory in this respect, in which case it is supposed that the issue of a C. of A. would be refused. But any such tests would seem to be carried out unofficially. There is, however, one case in which tests are laid down, as there is a regulation that requires the new aero plane to be tested for spinning by the applicants' pilot before being sent to the Test Depot. The official attitude with regard to this matter can be gathered from these regulations. In the case of the appli cants' trials it is stated that the machine is to be spun for four complete turns in each direction, and that it is to recover in two turns on reversal of the controls. If it does this it is to be considered as satisfactory. There is no regulation whatever dealing with the reluctance or otherwise of the aeroplane to go into a spin. In fact, a thoroughly dangerous machine which flicks into a spin without, warning passes with flying colours if it can be made to come out in the requisite number of turns, while another machine, the spinning of which might have taxed the ingenuity of the most skilled test pilot, would be re fused a pass if it took half a turn too much to come out. There is no doubt that while the latter machine might be thoroughly safe in the hands of the semi-skilled pilot, the former would be most dangerous. It is clear that these regulations are devised to insure that if an aeroplane goes into a spin, it shall be possible to get it out in a reasonable height. This is, of course, desirable, but it certainly resembles shutting the door after the horse is stolen. The unspinnable aeroplane is the target that should be aimed at, and extreme reluctance to go into a spin should be accepted, in lieu of the regulation recovery. The aeroplane which spins is only safe in this respect if it can be got out and is at a sufficient height for recovery. Aeroplanes which either do not spin or spin with extreme reluctance are safe at any height. There is another regulation which lays down the length of run which the aeroplane must not exceed in leaving the ground, and another which states that it must attain a certain height from the ground in a certain distance. These regulations are clearly designed to ensure that the machine should be able to get away comfortably from an oidinary aerodrome, and, as such, are desirable, but it is not easy to see why a further regulation should be added requiring that a machine should reach a height of 1,180 ft. in less than three minutes. The ideal type of aircraft for leaving any aerodrome would presumably be one which was capable of going straight up, as a possible helicopter might be able to do, but. whether or not it would reach the specified height in the specified time would have no meaning in connection with its safety. The same thing is true of the ordinary aeroplane, and the regulation has the unfortunate effect of hampering the development of cheap low-powered air craft, which might do much to popularise flying, as in such machines the minimum power requirement is con ditioned by this regulation. The important thing in this connection is angle of climb not rate of climb. There is, curiously enough, one matter in which the motor car is subject to regulation and the aeroplane is not. I refer to exhaust noise. In order to forestall an excuse for further regulations, it is most desirable to fit all civil aircraft with silencers. The complaints, very often justified, by those residing near aerodromes of disturbance from this cause will rise to a howl of indignation as aero planes become more numerous, and the result may be that regulations will be made specifying the number of decibels of sound that a machine will be permitted to emit, and a further trouble added to those already borne by our long-suffering designers. Rear Admiral Commanding Aircraft Carriers September 15 in succession to Rear Admiral Henderson, REAR ADMIRAL THE HON. SIR ALEXANDER RAMSAY C.B. Sir Alexander Ramsay is the husband of Lady became Rear Admiral Commanding Aircraft Carriers on Patricia, second daughter of the Duke of Connaught. 952
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
