◆ SpookStack

ATR COMMERCE BULLETIN 3l Duerr testified that very extensive saperl: ments respecting this possibility bad n fouducted by the builders and the regults a = to the bull, had pull out; that all been reassuring. When the engites are of t ie: ] the small frame horsepower the rest the stern had broken in tension ; Bea ie ’ that only a few of the atall tabs of metal from the peri hery of the frame. which bee ted: of the bight formed where the radial wires hooked on to the frame, aT Were found on the ground below where the | ture of the exhatst gases is 450° to 480° back of the cylinder. With a mizture of air Sucked in. the temperature is reduced to 280° to 250° C. Visible sparks have a tem- perature over 500° C but lose their heat rapidly as they are impelled through the air. Play before the elapae of the 4-minute tn- terval between the dropping of the trail ropes and the accident, bat the heat of the exhaust gases caused the havoc ig also improbable. “If ignition Was atressed for greater loads than the tén- sional strength of the bow t: rane, and that the rope had not pa Fufther- more, 1t war observed that the eye through which the trall rope was attached to the ship and the jongitudinal member to which the eye was affixed, were intact after the accident. The four members of the crew in the atern of the ship testified that ther did not hear or gee any such structural fallure prior to the fire. IGNITION OF THE MIXTURE Many of the theoretic aspects of the ig- nition of the combustible mixture were dealt with at great length by ea number of experts, Only a summary of this phase of the investigation is related in this report. MECHANICAL If there had been enough heat generateg by the friction of wires or other members oO 3 with each other, due to structural failure or breaking, 9 suficiently hot spark might have 1 produced to set of such mixture. There js insufficient evidence to sustain a conclusion based upon this theory. CHEMICAL the Hindenburg and the Graf Zeppelin, no a been experienced from this ELECTRICAL Under the classification of electrical sources of ignition several were considered. A combustible mixture of alr and hydrogen could have been ignited by the overheating of wires carrying current within the ship, e. E. by a short circuit. Berring the possi- bility previously alluded to, of a substantial it 1s thought to have been only remote fred Gefect or failure of the ship's electrica] Wiring, According to witness Lenz, who was sta- tloned in the electrical power Plant at the time of the accident and bad most of the ship's electric indicators. fdsea, and cir- cult breakers under ohservation, the vari- our circuits were functioning normally just Prior to the conflagration, “No fuse blew or circult-breakers operated at that time. It was also observed that the cable carrying the current to the stern light was very sturdy and was installed So as to provide plenty of slack to compensate for expansion and contraction of the frame of the ship, BPARE IN GAs FULLNESS OR PRESSURE INDICATOR A theory introduced by witness Heinen Was that the cause of the fire waa due to the ignition of such mixture in one of the Gat fullness or pressure electric meter ac- tuating units fixed to the axial corridor in the vicinity of cells nog. 4 and 5, He he- Heved that a smal] pocket of gas accu. mulated in the folds or ridges of the cells surrounding the corridor and found its way into the inner recesses Of the meter and was there ignited by an electric spark: that the fire thus created traveled up along the ing of such wires in the aft end of the ship, y a terially lower jts ordinary feuition temper- ature, but it does not appear that anv gach metal wae in that part of the khip were the fire was frst observed. Under the title of chemical possibilittes there has also been Buggested that a flame Might have been produced br spontaneous combustion. The evidence is inadequate to support this theory. THEEMODY NAMIC In the examination of thermodynamic pos- sibilities much time at the outset of the in- vestigation was given to the possibility of such mixture being ignited by the Sparks from the engine exhausts. It was suggested that sparks or larger particles of carbon prer the exterior of the stern ond there culation of the exhaust gases, set up by the e in reverse and the forward engines idling ahead) was different from that predured while under way, it was maintained by the German experts that this clrenmstanee Would not result in sparks or carbon par- outer cover: that the relatively slow burn- ing of such free hydrogen would account for the peculiar Manifestations of iilumina. Hon described by certain witnesser: that the fire in the kecond sequence then de- pirosed Bag cell no. 4, as seen by witness u. been able to ignite euch mixture on the top of the ehip at least 165 feet away from the after exhaust outiets. Witness Ludwig