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Aviation History
1930
UNTITLED0 - 1524.PDF
FLIGHT, DECEMBER 12, 1930 :.£.".. •3.:.: R101 INQUIRY AS stated briefly in our last issue, the Inquiry into the lossof R 101 was re-opened on Wednesday, December 3,in the hall of the Institution of Civil Engineers. The Solicitor-General produced some further papers, among thema letter from Col. Richmond, dated October 24, 1929, which gave a table of excess weights in the metal work. There wasa total excess of about 14 J tons over the calculations. Mr. Gearish, shed manager at Cardington, said that whenthe ship was in as good a condition as could be expected, there was an average leakage of 22,588 c.f. of gas in 24 hours.The loss on R 100 was 80,000 c.f. Professor Bairstow gave the result of his calculations onthe effects of loss of gas. He said that the total deflation of any two adjacent gas bags in the forward part of the shipmade it impossible in certain cases to maintain the horizontal trim of the ship, whatever was done with the ballast. Themost extreme results were given by gas bags Nos. 4 and 5. At a speed of 55 knots, the deflation of any one gas bag fromNo. 3 to No. 8 would give a pitching moment greater than could be corrected by the elevator. He said that a gust or alull would make it more difficult for the man in charge to apprehend what was happening, and that a lull might turnthe scale towards disaster. On Thursday, December 4, the Solicitor-General said it hadsince been calculated that R 100 before starting for Canada lost 45,000 c.f. of gas a day, not counting one bag which lost22,000 c.f. a day. After the ship returned, not counting a bag which lost 21,000 c.f., the loss was 43,000 c.f. Dr. Eckener's Evidence ; Dr. Eckener then gave evidence. He had written it out in German (though he speaks good English), and it was interpreted. The statement began as follows :— " The extremely interesting and clear statements given yesterday byProfessor Bairstow based on the experiments made in the wind tunnel clearly show that by assuming certain losses by gas it would be impossible to preventan airship of the R 101 type from stranding in a trim and loaded condition, as was the case with the R 101 immediately prior to stranding, unless therebe, for instance, sufficient time to retrim the ballast. " Professor Bairstow, in my opinion, has dealt in a most convincingmanner with all the factors determining the pitch movement. I particularly agree with him that the elevator is rendered ineffective when the ship comesinto certain out-of-horizontal position, and also that heaviness of 13 to 15 tons is the maximum which can be carried dynamically. Yet I was somewhatsurprised by the factor of pitching moment which he used for the effectiveness of the elevator. It is about double that which we calculate for the ' GrafZeppelin.' For this ship the pitch moment is only about 2,000 ft.-tons in the event of the ship flying heavy in horizontal position : that is, this wouldapply only by assuming that it is at least 10 tons heavy." Professor Bairstow, the statement continued, used a figure of more than3,000 ft.-tons. The trim moment of the elevator alone in the " Graf Zeppelin" was only about 1,000 ft.-tons at an angle of 25 deg. up or down. He admittedthat he did not know exactly the moment of the R 101, but were the figures of the two ships similar it would be impossible to keep the ship in a horizontalposition if she had a loss of gas of about 1,200 ft.-tons pitching moment, assuming the total heaviness to be six or seven tons. This position wouldbe brought much nearer if the speed of the ship, as no doubt it was, had been reduced to two-thirds by then, thus reducing the effectiveness of the elevatorto only one-half. This would seem to be of value only from a theoretical point of view, but taking into account that the ship was heavy as a wholeand nose heavy and could not keep, or could only temporarily be brought back to, a hori'ontal position, one had to imagine a process of straining inwhich the pitching moment might become effectively a question. " In forming my opinion," the statement continued, " I commence withthe fact that the ship made a sudden and very steep dive and that, in spite of the probable dropping of ballast, she could no longer be kept on a levelkeel, although she had been able up to that moment to hold her altitude. It lies very near at hand to connect sudden occurrence of head heavinesswith the particularly steep dive, because the steep dive itself can hardly be explained by the sudden loss of gas, because the fact of a rent in one ofthe fore gas-bags would not show itself suddenly. " The whole happening was no doubt as follows. At 2 o'clock the new'watch came on to take over the control of the elevator. He (the coxswain) would have to feel his way into the static condition of the ship. This is anold experience. The weather was bumpy and the ship probably not only heavy—three or four tons—but a l'ttle heavy by the nose owin|» to theloss of gas in one of the forward gas-bags, in the same gas-bag which later sustained a large rent. It is very difficult at once to feel the head heavinessof the ship when the ship is heavy as a whole at the same time, because the static and dynamic factors would then compensate one another. It may now have happened that in a slight gust of wind the ship made a movementdownwards which the new coxswain of the elevator did not immediately and correctly counteract because he could not be quite clear about the conditionof the ship. " The movement became steep because the ship now received a currentof air from above on to her nose, thus accentuating the effect of the head heaviness. Gas between the gasbags and the outer cover escaped to the tailpart of the ship, thus increasing the pitch movement still further. Owing to this unusually violent movement of the ship the already damaged gas-bag received a large rent from which the gas now quickly escaped, going into the tail. Thus it took some time (perhaps fully 30 seconds) to bringthe ship back to a level keel." Sir John Simon asked whether that would be done by putting up theelevator. Dr. Eckener.—By putting up the elevator or by dropping fuel.The interpreter continued the reading of the statement, in which Dr. Eckener said : " Probably—and on this point I agree with Professor Bairstow—this was possible only by dropping oil from the control car. This oil came to lie under the stranded*ship owing to the fact that the vessel, throughher reduced speed in the strong wind, was making very slight way over the ground, which I estimate at four to five miles an hour. The ship havingrighted herself through the throwing out of ballast was unable to maintain her horizontal position by reason of the fact that the gas continued to escapequickly." Sir John Simon.—At the moment, as you reconstruct the position, do youconsider that people in the control car would know that they would be going down ?Dr. Eckener.—Of course. Therefore they would stop the engines. Replying to another question by Sir John Simon, Dr. Eckener said hisreference to a pitching moment of 1,200 ft.-tons and a heaviness of six or seven tons applied to the " Graf Zeppelin," and he used it as an illustration.He thought the R 101 would be 3 to 3) tons heavy because of rain and because of the loss of gas due to the ship going above pressure height at the start.He assumed that when the ship got back to horizontal by dropping ballast she lost speed, and also continued to lose gas. As a result the elevatorscould not do what they could have done before. The elevator moment, the pitching moment, was reduced to about half. Sir John Simon.—Do I understand your view to be that those in chargeof the ship, after putting up the elevators and getting the ship horizontal or perhaps even a little nose up, would at that moment begin to realise thatthey could not keep her horizontal'? Dr. Eckener.—Perhaps a little earlier. I realise that it must have been verydifficult for the commander to decide to drop oil, because he needed it before he got to Egypt, and would try to save oil. It might happen that the shipwas diving for 10 or 12 seconds, perhaps 15 seconds, not more. Of course, the commander would be hesitating to drop oil until this moment becausehe hoped that it would be possible to get the nose up by the elevators, and when he saw it was not possible to do so, then, in my opinion, he would dropoil. Sir John Simon.—That would be a difficult decision for a most experiencedman to make in a quarter of a minute ? Dr. Eckener.—I would have myself waited at least 12 or 15 seconds.Hoping to be able to put yourself right ?—Yes. Putting yourself in his position, because he was a very fine and experiencednavigator, if at the end of that time you realised that the elevators alone could not do it, you would drop oil ?—-Exactly.In the meantime the ship would have lost speed ?—In 10 seconds a diving ship loses about one-third of its speed.If the captain came to the conclusion that the ship must go to the earth, what do you think he would do as regards the engines ?—He could only stopthe engines. In order to reduce the severity of the blow ?—Yes.What do you think would be the cause of the fire ?—A broken electrical wire. Dr. Eckener added that during the war hydrogen-airshipshad more than once struck the ground without catching fire. He stated that the next airship to be built in Germanywould use helium. He said that the " Graf Zeppelin " would not lose more than 7,000 to 8,000 cub. ft. of gas whenin the shed. Sqdn.-Ldr. Booth paid a high tribute to Flight-Lieut.Irwin and Lieut.-Commdr. Atherstone as airship officers. In general, he agreed with what Dr. Eckener had said. Quiteindependently he had arrived at the same general conclusion. On Friday, December 5, various evidence was taken.Mr. T. S. D. Collins, head of the stressing department at Cardington, said that he did not think the disaster was-caused by loss of gas. He could produce calculations to show that there was an ample margin of safety. He thoughtan unexplained dive might have occurred, such as he had once experienced in R 33. Capt. Meager, first officer j ofR 100, and Sqdn.-Ldr. Warm, late captain of R 38, both attributed the disaster to loss of gas. All the airship officersspoke of the shortness of the training the crew had^had after a long period in which no airship was flying. The Inquiry then terminated. . R.A.F. Siam Flight AIR MARSHAL SIR GEOFFREY SALMOND, Air Officer Com-manding R.A.F., India, returned to Delhi by air from his visit to Bangkok and Singapore on November 21. Ba,d weatherdelayed him and his escort one day. ** Britain and the Schneider Trophy REPRESENTATIVES of the Air Ministry and the RoyalAero Club met on December 8 in order to discuss next year's Schneider Trophy contest, which is to be held in Britishwaters. Challenges are expected from France and Italy, and, possibly, the United States. The conference decided to appoint a sub-committee to consider further the formwhich the national effort shall take. The sub-committee consists of Comdr. James Bird and Lt.-Col. W. A. Bristow,for the Royal Aero Club, and Air Commodore F. V. Holt, Director of Technical Developments, and Mr. B. E. Holloway,one of the principal assistant secretaries of the Air Ministry. The Fairey in Belgium FOLLOWING the order for 45 Fairey " Firefly " fightersfrom the Belgian Government, we understand that the Fairey Aviation Co., Ltd., gave a demonstration at EvereAerodrome of the III F two-seater reconnaissance machine. 1446
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