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Aviation History
1920
1920 - 0239.PDF
FEBRUARY Z6, 1920 v CORRESPONDENCE [The Editor does not hold himself responsible for opinions expressed by correspondents. The names and addresses of the writers, not necessarily for publication, must in all cases accompany letters intended for insertion in these columns.] PARACHUTES ANCHORED AND FREE [1997] I had not intended to trouble you again, but it seems advisable to clear up the confusion which7 has arisen owing to the different meanings attached by myself and your other correspondents to the term " Positive." And first, may 1 say I unreservedly accept Mr. Calthrop's disclaimer at the commencement of his letter in the spirit in which it is made. The term " Positive " was used by me to denote that type in which, generally speaking, the para- chute is withdrawn from its receptacle by the positive pull on the life-line engendered by the difference in motion of the passenger relatively to the aeroplane. I do not like the.word, and should not have employed it had I not been under a misapprehension as to its use by the Parachute Section. I much prefer my own term " Anchored," and would define it thus—" A parachute system in which mechanical con- nection between the flying machine and the passenger persists after the latter has left the machine and in which the with- drawal of the parachute from its case is effected or initiated wholly or partially by the subsequent difference in rate of direction of motion of the passenger relatively to the flying machine." A " Free parachute," on the other hand, is one in which there is no mechanical connection between the machine and the passenger after the latter has left it, and in which the withdrawal of the parachute is independent of the rate or direction of movement of the aeroplane relatively to the passenger. At present the " Free " type is very much in the background, but if there is any truth in my contentions, this type must comt much more to the front, and this division into " Anchored " and " Free " types represents a funda- mental difference in the mechanical principle. I will accept Mr. Calthrop's and Mr. Smith's use of the term " positive" to denote the " open mouth" type of parachute, and perhaps in return they will allow me to substitute for " non-positive " which is a merely negative qualification, the terms " pneumatic " and " semi-pneumatic," according to whether the parachute is inflated solely by im- pact of air at the mouth or whether it is assisted by an auxiliary mechanical device other than the permanent open mouth. Thus we can divide the " Anchored " and " Free " para- chutes each into three sub-divisions :—Positive opening, Pneumatic, Semi-pneumatic. Now, if Mr. Smith will refer to his letter again and sub- stitute " anchored type " for " positive," he will see that " my sweeping condemnation," as he calls it, refers to the "anchored" system and not per se to the open mouth " method of stowing, which is admittedly admirable. • Now, to turn to Mi. Calthrop's letter—here, again, the same confusion has arisen owing to the sense in which I applied the term " positive " with the result that 1 am afraid Mr. Calthrop thinks I have drawn an unfair inference from the accident in America. I certainly understood that he claimed " infallibility" for the Guardian Angel parachute system as a whole, and not merely for the " open mouth " method of stowing, and I cited this accident to show that the " anchored " system used in this parachute, requiring a life-line mechanically connected to the flying machine, was not infallible. I cannot see how his proposal to put this life-line in a sunken groove makes much difference ; when the critical moment arrives it will have to leave its groove and it will then be as I said " dangling in proximity to the machine " just the same as if it had never been in its groove. Touching this accident I entirely accept his account, more especially as it is exactly what I heard myself. Mr. Calthrop is indisputably the pioneer in scientific life parachute construction, and although I have been ex- perimenting with parachutes I think as long as himself, it has been only in connection with flares and other dead loads till quite recently, and it is with some deference I am going to say this ; but it seems to me that his remarks as to the necessity for " shielding " the rocker, and his plea that " all projections and rugosities should be ' smoothed off ' the fuselage," constitute the most deadly criticism of his own and similar " anchored" systems that lias yet appeared. The late Lord Rayleigh, one of the greatest mathematicians of his day, assured me that it was impossible to forecast by mathematics what would happen to any of these parachute systems in case of an aeroplane crashing, there being too many uncertain factors. We must form an opinion by com- mon sense. Common sense suggests that a parachute system which requires " all projections and rugosities " to be removed from the fuselage does not seem likely to be re- liable in the event of a machine falling in a " spinning dive " or rolling over with perhaps one broken wing hanging down in an unknown position. Mr. Calthrop has cited two of his many patents as examples of " special adaptation to en- vironment," but he has made no reference to those other forms admittedly designed to cope with different types of accident, and to which my comments were especially directed. I am told that the Spencer " Salvus " parachute is a beauti- ful piece of mechanism, but if I understand it aright, it falls under the head of " anchored " parachutes. Apart altogether from the question of reliability, no one has yet explained how more than one or two of these anchored parachutes will be carried on one machine whereas with the " free " type, each passenger carries his own parachute. «In conclusion may I say this, and I trust Mr. Calthrop will not take it as implying the slightest criticism of himself, as nothing is further from my thoughts ; that throughout this correspondence, at the sacrifice perhaps of more effective replies to some of your correspondents' arguments, I have purposely avoided any reference to my own " compound parachute system," because I felt it would be a pity to let tins correspondence degenerate into a mere discussion between different inventors as to the merits of their respective in- ventions. As you, Mr. Editor, said, it is much to be desired that outsiders with parachute experience should join in the discussion. Unfortunately I am afraid there is no man living who has escaped from a flying machine in process of crashing. It is all the more to be hoped that the authorities should not delay further in carrying out really practical tests as suggested by Mr. Smith. A fine opportunity was lost when all those old flying machines were broken up after the Armistice. Travellers' Club. H. S. HOLT. P.S.—Since writing the above, I have had the pleasure of reading Major Orde Lee's letter. The Major is, I believe, in the service of the Calthrop Co. ; otherwise his opinions as a practical parachutist would carry even greater weight. Like your other correspondents', his letter is largely a reitera- tion of the necessity for non-entangleable rigging and for the " held-open " mouth or " positive opening," to counteract suction. No one in his senses disputes the necessity for the former, or the efficiency of the open mouth as an antidote to suction, that worst enemy of the parachute, owing to its sucking the inner surfaces of the parachute together and resisting inflation. But it does not seem to have occurred to any of your correspondents that it might be possible to construct a " free " parachute system with non-entangleable rigging, and in which there is no suction potential or actual. Such a parachute will function regularly and certainly, un- assisted by the " open mouth," with its several drawbacks and limitations. To " eliminate " is usually better than to " counteract." FLYING AND CURIOUS PHENOMENA[1998] In answer to your letter appearing in FLIGHTof February 12, under No. 1994 as reference, I would tell you that if you would have dived on that occasion you wouldhave seen the " top " of the rainbow, and halfway to the ground you would have seen the rainbow completely round.I have witnessed it myself as I was flying with my father and another pilot at Brussels in October, 1919 (they both saw^it,too). The explanation of this is quite simple and natural. Youwill find it in the explanation of the rainbow itself. WILLY COPPENS,Belgian Air Attachi in London. PROPOSED AERO CLUB OF SOUTH AFRICA [1999] At a meeting held recently, and attended by Major H. R. Coningsby, representative of Messrs. Vickers and Messrs. Wolseley Motors, Ltd., Capt. P. C. Passman, of Messrs. Nieuport and General Aircraft Co., Ltd., and representatives of Messrs. the Handley Page South African Transports, Ltd., together with many ex-R.A.F. officers and others interested in the advancement of aviation in South Africa, it was resolved that a club be formed with aims as follows :— (1) That it be called the "Aero Club of South Africa," and run on the lines of the " Royal Aero Club of the United Kingdom." (2) To obtain recognition from the " International Aero- nautical Federation," as a responsible body governing civil 239
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