Sunday, September 11, 2011

Why did the L-8 deflate?

There are some questions that became apparent while I started researching the mystery of the L8 that became significant later on.

The first was why the blimp was deflating as in drifted towards the beach off the Great Highway.
Obviously, the loss of helium in the balloonets, but what caused the loss?

The possibilities include things like bullet holes, tears and punctures of the bag. This would be a reasonable first guess. Given the lack of evidence in the common understanding of the story details, it's also a likely one.

When I first started hunting for details, this was my working theory.  After I found the L-8 inquest folder and digested the testimony, the premise quickly faded away. I had thought that the L-8, which should have had three people on-board, might have been over-weight due an already existing person being inside. In flight, the intruder surprised the crew and shot them, in the process puncturing the balloon. This theory actually seemed good when I read that in the weeks prior to the incident, a man was spotted breaking into hangers, leading to a running gun battle through the streets. Spies had a definite interest in  what was happening at Moffett Field and Treasure Island, and so I thought a spy might have attempted to see what secrets could be gained by getting on the L-8 flight. That is it seemed possible until I visited the L-8 in Pensacola. There is no hiding space that would make this a practical consideration.

The L-8 was deflating when it came rolling across the beach, dropping onto the gold course south of San Francisco. This means whatever happened occurred at sea. This lead to another popular theory that the L-8, while investigating the oil-slick that may have been a possible submarine contact, and that the L-8 crew were attacked and over come by the crew of the enemy submarine. Also a valid working theory, until we read the testimony. The crews of the Albert Gallatin and Daisy Grey were watching the whole time as the L-8 circled the spot, up until it turned about-face and started to head back to Treasure Island, under control and normal operating condition. The only notable facts about this are that they would normally have continued onto the Farralone Islands during a normal trip. The second fact is that they dropped ballast when they turned back. They never came close to the surface of the ocean according to any of the witnesses -dispelling another theory that the crew may have been too close to the water and were sweep away by a wave. The metal used in the gondola would have showed etching if it came in contact with seawater and the repair crews reported there was no sign of seawater in or on the gondola.

The L-8 would pop up and return to air when one of he two 350 pound bombs attached tothe gondola was knocked off at the golf course. Still venting gas, it would come to it's final resting place in Daly City.

The answer of why helium was lost in the first place comes from the blueprints of the L-8 I found with the inquest testimony.

The L-8 and other blimps, were equipped with an automatic valve that opened when the blimp went to high and, since the bag would expand with the lower outside pressures the higher it went up, could potentially burst the balloon unless gas was vented. The L-8 was set to automatically vent at 2500 feet. This prevented a catastrophic failure of the balloon. The crews would be able to drift down slowly if the controls or crew  were disabled.

You can see the vent in the picture of the L-8 as it floated above Daly City just before it's final crash.

So why did the balloon go higher than 2500 feet? The L-8 suddenly lost it's two crewman, and lightened by the weight of two men, suddenly popped higher into the sky. Rising above the 2500 feet limit, the valve opened as designed and started to cause the decent of the, now crew-less, L-8! The winds pushed the L-8 towards the beach and the more public part of the story.

Thanks for reading the blog, L-8 fans! More to come in the future. Stay tuned!


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Comments should be topical and civil. Questions are welcome but I may not be able to always supply answers. - Otto