USS Long Island—Theory & Design Part Three

LOOSE BRIDGEWORK

The altitude pilot’s position in a rigid airship is greatly under-appreciated. When referred to simply as the “elevator man,” we miss the fact that only the most experienced hands who had developed a sort of “sixth sense” for attitude drift could hope to preempt pitch changes with orchestrated elevator tweaking. In any design, the altitude pilot’s outboard facing position is not negotiable, be it the Brits’ right hand drive (above) or the standard Zep port side.

Left- or right-hand drive elevator, helm perfectly center or off-center, bridge design was fairly consistent from R.100 (upper photo) to LZ-130 (lower photo).

Akron/Macon three-compartment bridge/car (diagram) retained the earlier Zeppelin port side altitude pilot wheel and centerline rudder wheel. Its aft center compartment was also a throughway from the folding accommodation ladder to a fixed ladder leading up to main ring 35, which gave access to the outboard companionways, centerline passageway and officers’ cabins forward. (Nothing in the literature suggests the space labeled “photo lab” aft of the radio room was ever finished as such.) The bridge/car was made more comfortable by engine manifold-heated ducted air.


We see nothing wrong with the Akron/Macon bridge design. One could easily add later 1930s enhancements, such as the lifesaving radio altimeter to supplement the annoying whistle of the sonic altimeter. They were already installing other advanced electronics in 1934, such as the radio direction finder.

For an airship designed from the outset as a flying carrier, as suggested by C.P. Burgess, a “pri-fly” for airplane control would be a necessary design element, in a second deck below.  Macon officers had tried to expand the position of senior aviator to also direct the airplanes. Such a billet would  certainly been on the duty roster of the ZRCV.

This greatly enhanced job/post of “Air Boss” would work hand in glove with the bridge, just as on today’s flattops. That station, for which we can borrow the modern term “pri-fly,” would need a commanding view of the keel to direct airplane launch and recovery. Effectively, he would serve as local Air Traffic Control.

Meanwhile, the Akron/Macon accommodation ladder never seemed quite long enough; our Long Island will have a reinforced double extension accommodation ladder. Like the ZRS ships, ladders will lead straight up to the hull through the pri-fly and bridge. A slightly retractable wheel, replacing the bumper bag  and similar to the LZ-129/130, would allow the Americans the luxury of more easily controlled wheel landings, which the Germans came to appreciate – then unfortunately set aside by request in May 1937.

This lower deck also would be the logical if somewhat exposed position for the radio room, since much of the ship’s communication would be with her airplanes. The ship’s radioman and/or navigation position would evolve to include scout airplane report coordinator, in a compartment with plotting board – in other words, a Combat Information Center, more advanced than the evolving ZRS-5’s.


MOTOR-VATION

Few engines were ever designed specifically for airships, and even fewer were actually produced. Long before LTA had to make do with adapted airplane engines, the maritime industry supplied much of the motivation.

The mighty 12-cylinder Mybach VL-2 (photo, awaiting installation in Akron) powered LZ-126 and LZ-127 as well. Its 550 horsepower was too little for the LZ-129 and would have been too weak for the 10 Mft3 ZRCV, let alone the 12 Mft3 Long Island. Of course there was the lure of America making a flying weight diesel engine ala ‘129-130; its stronger torque in its lower RPM range helped big prop tips not break the sound barrier. However, it is most likely any ZRCV design would have used the same gasoline as its airplanes, avoiding the complexity of a dual fuel system.

More likely, American industry, building ever larger and more powerful radial engines for new all-metal high-performance airplanes, would have gotten the contract. Macon’s replacement engine from Packard, on the test stand when Macon was lost, might have powered six engine cars for a ZRCV or even could have be put in tandem for the Long Island cars.


Of greater importance to the movie is what the engine/drivetrain would have looked like: internal ala ZRS-4 &-5, or external car/pod mounting.
R.101’s power cars (photo above) contained both a Canadian railroad diesel engine and its gasoline starting motor.

Akron/Macon’s keel-integrated engine rooms (photo, on a combined structure/drivetrain stand) are not very visually appealing. Then there is the vexing question of “vectored thrust.”


VECTORED THRUST—IN 1906

“Vectored thrust” is an arrangement to swivel the prop to push the airship in a particular direction. We are not sure it was a new idea when seen on the Melvin Vanniman airship America in 1910. The British R.9 was so equipped (photo).

Even the Germans had even tried swiveling props, briefly on LZ-127 (LZ-Archiv photo) but rejected the idea. Remembering the Mybach VL-2 had dual cams, so as to be reversible, the ability to push or pull the ship in any direction was a capability not lightly discarded. (Pity the Italians, without revering engines or gearboxes, had to stop engines and send a crew out on the stanchions to change props!)

Yet Rosendahl lamented, “That German airship men did not like the AKRON-MACON design is not exactly a secret…These two airships were equipped with swiveling propellers in order to provide vertical thrust up or down; however, the modest advantages derived therefrom were not worth the cost and complication. The location, in line, of the four propellers on each side, proved inefficient and a source of serious vibration.” The Macon “post-mortem” recommends deleting the complex geartrains in all but perhaps the foremost engines.

WATERWEIGHT

Also of importance for art direction is the question of the water recovery equipment’s appearance. One can barely see the water-weight recovery system on Hindenburg—a thin line amidships at the equator. It was a rain gutter that collected runoff when the ship was run into the clouds to make up some burned off fuel weight.

The weighty complexity of condenser stacks and associated plumbing (early Akron, photo) would have been the first tonnage deleted in a conversion back to hydrogen; indeed, #3 and #4 were removed from Macon to save weight in 1934.

Nonetheless, the American ability to recovery water from exhaust was so desirable the Germans might eventually have added H2 to their diesel fuel to recover lost fuel weight even before LZ-130. Remembering the Lakehurst innovators had developed and fitted the Mk4 condensers to Akron by ‘33, designers were advancing toward solving the problems of soot buildup, improving the weight ratio and the efficiency.

The logical solution is found by looking to the last rigid airship, LZ-130. Of his many wonders, many of which we may never appreciate, most easily notable are his engine cars (photo montage). The first and only “tractor” configuration for a Zeppelin, the barrel/pod-like power cars conceal several advanced engineering developments. Initially equipped with the same double connector and the stacked two-blade props, the marvel-in-disguise cars show cooling radiators forward. However, these are more complex than meets the eye, for they contain oil cooling and exhaust condensers as well. Also, the water recovery system was wholly enclosed in the cars. A shaft-driven turbofan  helped rush that airflow out with such thrust it was said the drag penalty was wholly paid back (!)

Though arguably never developed without the LZ-129 fire, since the necessity to limit static discharge and also recover water might not have evolved, we think it an acceptable stretch of the truth that such technology was created anyway. Of course his syn-diesel had to have hydrogen added to make water recovery possible, but perhaps gasoline versions would be selected by the US had the Packards made for Macon not evolved into larger engines. Zeppelin engineman Eugen Bentele told the producer the German engineers never really solved the soot problem, but by the time of the Long Island, and her gasoline engines, perhaps a less strenuous method of cleaning out the carbon would have been developed.

Later flights featured single-hub, laminated three-blade props that improved efficiency (photo). These raised the bar for future rigids.

In Part 4 we will see a magazine cover that suggests such cars would be part of the ZRCV, so these power cars on our movie airship are not much of a stretch. Either way, one has to acknowledge it’s a lot more visually interesting for enginemen to loop an arm around the station and egress the engine cars via the ladder!

So we have the most important design details of our USS Long Island ready for the screen: 944 feet long, 160 feet in diameter, four engine cars, strong fins, double-deck control car.

However, that was only the foundation. USS Long Island, of course, is a flying aircraft carrier, and we shall make her so, in Part 4.

Read on to USS Long Island Theory & Design Part Four

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