The Story of the Airship 8

The Story of the Airship 8

Wartime ships carried three to five men and a day’s fuel. Today’s carry

eight or ten, enough pilots, radio men, navigators, riggers and

mechanics for two full watches, though normally everyone is on duty

during patrols. The “B” was good for perhaps 900 miles, the “K” for well

over twice that distance.

 

Wartime ships had to keep the control car well away from the bag to

prevent sparks from igniting the hydrogen gas. A windshield was the

pilot’s only protection from the elements. Modern ships, using

non-inflammable helium, have closed cars, streamlined into the bag,

ample room for navigation and radio, sleeping and eating quarters, even

a photographic dark room, can be heated and noise-proofed.

 

Early airships were pulled down and held by a large ground crew, a

pneumatic bumper bag on the car cushioning its landing. Today’s ships

land on a swiveled wheel, roll up to a mast—or taxi off across the

airport like an airplane and take off.

 

These, however, are merely flight factors. More important is it that the

wartime blimp was to a large extent hangar-bound. It could go no further

from its base than it could safely return before its fuel was exhausted.

 

Today’s ships are expeditionary craft, can go almost anywhere, stay as

long as they want. They are no longer land-bound, can be refueled and

reserviced at sea. They are much safer, rank high in this respect among

all carriers whether on land, sea or in the air.

 

Three independent lines of study contributed to these results, those of

the Army, Navy and Goodyear, each free to follow its own ideas, to

observe results found by the others, adopt them, use them as starting

points for further developments, or discard them.

 

The improvements were achieved in a relatively short period. The army

started in after the war and carried on a continuing program till 1932.

The Navy, absorbed in its rigid airships, did not get into non-rigids

till the early 1930’s. Goodyear built the Pilgrim in 1925 but its

development program really began with the blimp fleet in 1929.

 

Noteworthy improvement was found during this period in materials,

structure, design, engines and radio communication, with outstanding

advances along three major lines.

 

First was increased safety, permitted by helium gas. Wartime airships

used hydrogen because it was all they had, had to develop what

protection they could against fire through construction devices and

operating technique. Hydrogen was not only inflammable, but under

certain conditions explosive. World War pilots had to fly their hydrogen

ships through thunder and lightning storms, dodge inflammatory bullets

if they could. Zeppelin sailors wore felt shoes, with no nails to create

a spark, used frogs for buttons, had to guard against static.

 

It was a fortunate thing for the airship world when a gas was found in

1907 in Dexter, Kansas, which would not burn. Curious scientists, asking

why, found it was helium, a gas previously identified (in 1869) only in

the rays of the sun. Helium gas is inert, refusing to combine with any

other element, does not deteriorate metal or fabric. It was not much

heavier than hydrogen, the lightest of all gases, so proved a welcome

gift to lighter-than-air.

 

For some reason, not explained except on the theory that Providence

takes special interest in America, helium has been found in quantity

only in this country. It is a component, present to the extent of two or

three percent in certain natural gas, though ranging as high as eight or

ten percent in favored areas. It can be separated by compression and

liquefaction from the natural gas,—which is that much improved by the

removal of the non-inflammable content.

 

The world’s chief known supply of helium lies in certain sections of

Texas, Kansas, Colorado and Utah. More important, United States is the

only country having great pipe lines, can distribute natural gas from

Texas to cities as far away as Kansas City, St. Louis and Chicago.

Without such a market operators would have to separate and release the

95% of natural gas to get the 5% of helium, and costs would be still

higher.

 

Helium is perhaps the most useful of the few natural monopolies given to

this country.

 

It was only toward the end of the World War, however, that Army

engineers worked out a process of separating helium from natural gas. A

plant was built at Fort Worth and the first cylinders of helium had

reached New Orleans ready for shipment to France to inflate observation

balloons when the Armistice was signed.

 

Army, Navy and Bureau of Mine engineers worked thereafter to increase

production and cut costs, but as late as 1925 Will Rogers called

attention to the fact that the Navy had not been able to get enough

helium to supply both the Shenandoah and the Los Angeles at the same

time. If one was using the helium the other had to stay home. Two ships,

and only one set of helium, he commented.

 

The use of helium cut the casualty list on the Shenandoah, would have

saved the Hindenburg. Non-rigid airships have had no fire or explosive

accidents since helium came into use as the lifting gas.

 

It was the loss by a hydrogen fire of the Italian-built Roma, after it

struck a high tension line at Langley Field in February, 1922, which

fixed the policy of “helium only” for U. S. Army and Navy airships. The

Army’s C-7 was the first airship to use helium. In building the Pilgrim

in 1925, Goodyear followed the same policy—even though it had to pay

$125 a thousand cubic feet for helium while it could have obtained

hydrogen for $5 per thousand.

 

Further improvements and increasing volume of production brought the

cost down in time from $125 to less than $20, and helium expense became

relatively unimportant in providing safety for Goodyear’s airship

operations.

 

Important too during this period was the Army’s development of tank cars

for transporting helium. A large item of helium expense was freight, the

cost of hauling 130 pound metal containers which held 170 to 200 cu. ft.

of the gas. It took 250 such containers to inflate Goodyear’s smallest

ship, the Pilgrim. The tank cars hold 200,000 cu. ft. of gas, almost

enough to inflate two Goodyear airships.

 

Experiments with specially woven fabric and the use of synthetic rubber

cut down the losses resulting from diffusion, and where formerly it was

necessary to remove the helium and purify it every six months, diffusion

losses were cut to one or two per cent a month, with purification needed

only every other year.

 

In addition to increasing safety, helium permitted improvements in

airship design. The wartime craft had its control cars suspended by

cables from finger patches cemented to the outside of the bag. But with

helium ships the car could be built into the bag, attached by an

internal catenary suspension system to the top of the gas section. Each

exposed suspension cable, no matter how small, creates parasitic

resistance from the air, so that the removal of yards of steel and rope

had the result of increasing the speed of the ship with the same

horsepower.

 

The second set of major improvements centers around the mooring mast.

The mooring mast idea was not new. The British had built the first ones

during the World War for its large rigid ships, found that a ship

attached to it would swing easily, like a weather vane, continuing to

point into the wind, and that a well streamlined ship would hold

securely even in winds of great velocity.

 

When Alfred E. Smith ordered a mooring mast built on top the Empire

State building, it was with the assurance from his engineers that even

with the tugging of the 150-ton Graf Zeppelin, the strain would be

little more than the normal push of the wind against the building

itself, that the added stresses would be negligible.

 

The Germans had had little occasion to use mooring masts.

Friedrichshafen, where most of the Zeppelins were built, lay in a

natural bowl, well protected from the winds, and ships could take off

and land, be walked in or out of the hangar with little risk from the

weather.

 

Lakehurst, on the other hand, lay in an exposed position, in the path of

coast-wise storms, a frequent battle-ground between onshore winds from

the ocean and storms breaking over the mountains from the west. A study

made later to determine bases for projected American passenger

operations showed that of weather conditions prevailing between Boston

and the Virginia Cape, those at Lakehurst were almost the most

unfavorable.

 

[Illustration: Four stages in the evolution of the mooring mast. At

the outset large ground crews held the ship on the ground.]

 

[Illustration: Then a stub mast was placed atop a truck, to hold the

ship on the ground, maneuver it in or out of the dock.]

 

[Illustration: A high mast, made in sections, can be erected

anywhere, anchored by guy wires, holds the airship securely against

winds of gale force.]

 

[Illustration: The little brother of the “Iron Horse”, which will

receive the largest of the new Navy blimps, maneuver them on the

field.]

 

People knew little about airship operating when the Navy base was moved

from Pensacola to Lakehurst on a waste site in the Jersey pine lands

which the Army no longer needed after the war as a proving ground for

its artillery.

 

This defect proved an advantage. The Navy was forced by the very nature

of things to concentrate on a problem which had been no problem to

Doctor Eckener and his associates. At the urging of Admiral Moffett,

Commander Garland Fulton, Lieutenant Commander C. E. Rosendahl and

others, Navy engineers built a high mast, 180 feet tall, following

British practice, with a service elevator inside, then tackled the

problem of keeping the ship on even keel against up and down gusts.

Since the wind does not come out of the ground, a low mast was

suggested, half the height of the ship, so that when anchored the ship

would all but rest on the ground. The Navy was working on this when an

incident happened to strengthen the argument.

 

The co-incidence of a wind shift, and rising temperatures one afternoon

as the Los Angeles was resting comfortably at anchorage, started the

tail rising, and it continued to rise till it reached almost 90 degrees.

Then the ship turned gently on its swivel, and descended easily on the

other side, with no more damage than some broken china in the galley.

Still a 700-foot airship has no business doing head-stands, so the low

mast development was rushed through. It proved successful.

 

The next step was to make the low mast mobile, so that it could not only

hold the ship on the ground but take it in and out of the hangar. First

of these was Lakehurst’s famous “iron horse,” a giant motor-driven

tripod, which rolled out on the airport, hauling incoming ships into the

hangar, took advantage of daylight calms to take ships out into the

field ahead of time so as to be ready to leave on schedule.

 

On the Graf Zeppelin’s trip around the world in 1929, hangars were

available for fueling stops at Lakehurst, Friedrichshafen, and curiously

enough in Japan, a German shed turned over to the Nipponese after the

1918 Armistice, having been re-erected at Tokio. There was none however

on the American West Coast to house the ship after its long trip across

the Pacific. So the Navy, under direction of Lieutenant Commander T. G.

W. Settle, hauled a mast up to Los Angeles from San Diego (it had been

erected there for the Shenandoah’s flight around the rim of the country

in 1923) anchored it with guy wires. It served the purpose perfectly.