DANGERS OF RIGID AIRSHIPS

Taranaki Daily News, 13 October 1930, Page 6

DANGERS OF RIGID AIRSHIPS

PROSPECTS OF LARGE VESSELS.

A PREDICTION OF FAILURE.

“We know enough now about the rigid, airships RICO and RlOl to feel confident that the failure of any element, whether of skeleton, of gas-bag wiring, or of envelope in either, of those great monsters will certainly result in rhe failure 1 of the whole ship.” This striking sentence is to be found in “About Airships,” a bok by E. F. Spanner, published in January, 1929. His preface states: “My own opinion about rigid airships is that they are, always have been, and always will be, unable to justify themselves for either military, naval or commercial, purposes.” Mr. Spanner states that in designing the RlOl, a very great deal of attention was given to the mathematics of rigid airship skeleton strength. One of the principal aims of the Government design staff was to arrange, the main transverse frames so that these should be sufficiently rigid in themselves to retain their shape without any transverse wiring. There would _ be, adde ’ Mr. Spanner, no intermediate transverse frames to add to the support given to the envelope by the main and intermediate longitudinals. “The skeleton of RlOl includes many important main members composed of thin steel tubes braced with duralumin stiffeners,” adds the writer. “The association of dissimilar metals in such

girders has been criticised, on aceou: of their different temperature co-offici cuts, and different tensile characteris-. tics. The criticism is a serious o.ne.”

Mr. Spanner finds fault with the design of both the RlOO and the RlOl in that the passengers are carried inside the hull. He says that stability of flight, while carrying passengers, in fair weather conditions, will be much more difficult of attainment than, either the Air Ministry or Sir Denniston Burney imagined. The ships would be much too unstable in flight to permit of it bein o possible to allow several tons of live weight to move about in an uncontrolled and uncontrollable manner.

He deals with superheating in airships, and says that the effect of the sun on the bags which support a rigid airship in the air is as unalterable in its character as is the effect of the moon upon the ocean. “If RlOl is in vertical loading equilibrium on an even keel when the sun is shining on her, she must inevitably be flown at a pitch of many degrees when the sun disappears and the gas cools down.” Extensive quotations from the log of tfie R 34, which crossed the Atlantic in 1919 are taken to show that airships suffer severely in storms, and the finding of the Court of Inquiry after the American dirigible Shenandoah was wrecked in 1925 is quoted to show that “there were no positive danger signs to warn the commanding officer of impending danger.” T. electrical effects of an airship passing through the air are also dealt with by Mr. Spanner, who says: “An explosive mixture of air and hydrogen is likely to be present —when it is most inconvenient —for so long as hydrogen

tis used as the lifting gas. No hydrogen- • filled airship can ever bo really safe against the effects of a spark discharge. Sparking can occur although no thunderstorm is anywhere in the vicinity. This point is not properly realised by the layman. Friction of the air on the cover, or of a rush of gas through the valves, has sometimes caused sparking which has resulted in the loss of the vessel involved.” Later' in the book Mr. Spanner- makes mention of the dangers of rigid airships, and says that there is nothing like the same possibility of safeguarding passengers that there is in an oceangoing passenger ship. ■ Summarising his arguments, Mr. Spanner says, inter alia: “A rigid airship will be exposed io atmospheric disturbances, severe ‘bumps’ or ‘dunts’, in weather that appears quite clear and fine. These will have a severe straining effect on the ship, and will expose the passengers to serious discomfort. , '■ „ • “In storms, the rigid airships, will he exposed to forces which are incalculable. The power of by no means a phenomenally severe storm was demonstrated by the breaking up of the Shenandoah. . . ~ . . “Increase in size of rigid airships inevitably leads to increase in envelope areas and stresses. In the event of their meeting storms, the envelopes of these new airships will be subjected to stresses far exceeding those which have fallen upon the envelopes of earlier skips.” In bringing th& boolc to a conclusion, Mr. Spanneiy after dealing with the possibilities of commercial airships paying their way, says: “I. am very

doubtful whether either of these greai monsters (RlOO and R 101) will be cap able of emulating the performances of the Graf Zeppelin. I have been so much imnressed with the likelihood that disaster will befall both of these ships that I have set out, as explicitly as I have been able (to show) just why, and where, I expect these new attempts at conquering the air with ligliter-thau-air craft to fail.”