FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1954
1954 - 1397.PDF
618 FLIGHT SLOW PROGRESS AT STRASBOURG... for routes to continue to be negotiated bilaterally, the basis of the proposal still evolves around a multilateral agreement and it is on this factor that there still remains a fundamentally different approach to the U.K. policy. At the end of the second week of the conference, these posi tions had not changed and it was decided to form a working party of the States who had declared definite positions to see if some unanimity could be achieved for submission to the main committee. There were not, at the time of writing, any changes in the positions adopted and it was the opinion of most delegates that there was practically no hope of any compromise which would lead to any substantial achievement. In other words, the conference appears to have resulted in the same basic position as that of previous attempts to arrive at any kind of multi lateralism on the exchange of traffic rights. It seems extremely likely, therefore, that on this particular subject any advancement which is made will be of a very minor nature. Non-scheduled Operations.—There has been only a very short discussion on non-scheduled operations and, here again, the results are likely to be disappointing. On paper, the position appeared to be quite hopeful, but when discussion began it was apparent that not much was likely to be achieved by way of liberalization and facilitation. Some States (notably Spain) stated that they were prepared to subscribe to a multilateral agreement, but added qualifications which would amount to restrictive practices on about 80 per cent of non-scheduled traffic. Owing to the short discussion on this item, it is really too early to arrive Concluded on page 625) EXPLOSIVE-DECOMPRESSION TESTS IN U.S.A. TN January 1952 the Lockheed Aircraft Corporation of Burbank, * California, began to incorporate explosive-decompression exer cises into meir high-altitude indoctrination training programme, the latter being offered to all flying personnel in compliance with U.S.A.F. regulations. A wide variety of tradespeople participated in these tests, and 381 experienced an explosive decompression. An extremely comprehensive account of these exercises has now been issued, and die more important results are tabulated on this page. The personnel involved were divided into two groups. The first was composed of those required to engage in actual flying under oxygen conditions, and their programme included a rigid physical examination, some six hours of "didactic instruction" and a low-pressure chamber ascent to 43,000ft simulated, followed by exposure to hypoxia* at 28,000ft, pressure breathing, simulated free fall, and an explosive decompression from 8,000ft to 25,000ft in less than one second. The second group of trainees, consist ing mainly of ground-servicing personnel, participated in a less intensive programme, two of the limits being 32,000ft simulated altitude and 20,000ft as the limit of explosive decompression. Lockheed's low-pressure chamber was divided into two com partments : the personnel cell (C-l) of 330 cu ft and the equipment test chamber (C-2) of 412 cu ft. A rupturable diaphragm was inserted into a lOin-diameter opening in die door connecting the two compartments and, by means of a spring-loaded drop knife, the diaphragm could be ruptured either by an instructor inside the chamber or by an external observer. The physical changes occurring in the chamber during and immediately after decompression were relatively constant, irre spective of the number of chamber occupants. Immediately fol lowing rupture of the diaphragm a loud, booming, explosive-type noise occurred. The noise was of an intensity approximating 130 decibels in the centre of C-l, approximately 5ft from die opening, and represented an increase of 60 decibels. Widi the movement of air from C-l into C-2, and the rapid pressure decay, a maximum temperature drop of 71 deg F ensued within 2 seconds. Condensation of water vapour and heavy fogging fol lowed almost immediately, and persisted for 5 to 15 seconds. The fog was sufficiently dense to obscure all chamber occupants. A sensation of extreme cold was momentarily experienced, with *Deficiency of oxygen in the inhaled air. TABLE III: PHYSICAL PHENOMENA IN ORDER OF PROMINENCE TABLE I: AGE-GROUPS OF Phenomena Noise ... Fog Movement of air Cold No comments 8,000-25,000ft (percentage of 234) No prev. decomp. (204) 65 13 7 1 14 Prev. decomp. (30) 68 7 18 7 8,000-20,000ft (percentaqe of 147) No prev. decomp. (136) 70 10 7 2 11 Prev. decomp. (") 80 10 10 TABLE IV : MENTAL RESPONSE Response Confusion Av. estimated time ... Max, estimated time... Fear or apprehension 8,033-2S,09Sft No prev. decomp. (204) 25% 2.4 sec 10,0 see. 43% Previous decomp. (30) 31% 2.4 sec. 3.5 sec. 41% 8,000-20,000ft No prev. decomp. (13*) 9% 2.5 sec. 3.0 sec. 30% Prev. decomp. (11) 20% 3.0 sec. 5.0 sec. 25% 20-29 30-39 40-49 50-55 Previous decompression ... PERSONNEL EXPERIENCING DECOMPRESSION 8,000-25,000ft 8,000-20,000ft (Percentage (Percentage of 234) of 147) 24 20 55 52 18 25 3 3 17 12 TABLE II: PHYSICAL VARIATIONS IN PERSONNEL 8,000-25,000ft 8.000-20,000ft Over-weight Under.weight Varicose veins Hernias Hypertension Hypotension Reduced haemoglobin Chronic sinusitis ... Hay fever ... Haemorrhoids Miscellaneous (234) 15 6 11 10 5 6 8 5 4 2 17 (147) 6 5 4 -x 1 restoration of the original chamber temperature occurring rapidly during the recompression of descent. A definite movement of air from C-l into C-2 could be identified by the occupants of the two rear seats. Balloons and strips of paper attached to the backs and sides of all seats revealed immediate but very brief displacement of air towards the opening. Disturbance in the air due to passage of the sound wave in C-l was noted by all personnel. Actual measurements of the pressure decay revealed the major pressure-change to occur in less than 0.7 seconds. The experiments were carefully controlled to reproduce, so far as possible, the conditions under which decompression might be encountered in actual flight; thus, several trainees resorted to regulator tube breathing to simulate loss of oxygen masks, some descended without oxygen, a few applied their masks immediately after decompression, while others activated their bale-out bottles in a simulated escape from the aircraft. The decompression from 8,000 to 25,000ft involved a pressure change of 5.4 lb/sq in and a wet gas expansion of 2.2 volumes; corresponding figures for the 8,000 to 20,000ft decompression were 4.1 lb/sq in and 1.7 volumes. In both cases the descent following decompression was begun within 30 seconds and usually proceeded at the rate of 4,000ft/min down to 12,000ft and 2,000ft/min thereafter. Altogether it can be concluded that die hazards of explosive decompression at altitudes below 30,000ft are by no means serious, particularly if previous experience under controlled conditions has been gained. TABLE V: BODY RESPONSE Region Chest: Movement ... Pain Ears: Clear before decomp. Pain during decomp. Sinus: Clear before decomp. Pain during decomp. Teeth: Pain on decomp. ... Gascro-intestinal: Distension or fullness Pain 8,000.25,000ft (Percentage of 234) No prev. decomp. (204) 46 89 7 94 2 14 2 Prev. decomp. (30) 52 93 7 90 15 17 7 8,000-20,000ft (Percentage of 147) No prev. decomp. (136) 47 2 84 12 94 2 2 1S 2 Prev. decomp. (11) 50 90 20 90 10 10 0
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
