The Story of the Airship 9

The Story of the Airship 9

The Germans, skeptical at first, became convinced of the value of the

mast, themselves erected masts at Frankfort, and Seville, at Pernambuco

and Rio de Janiero, used them as terminals.

 

Once the masting technique had been worked out, the Graf Zeppelin and

the Hindenburg, in the years 1930-6, made a record of regularity which

no other vehicle of transportation has approached. They took off at

times over the ocean for Europe when all other aircraft in the area was

grounded, when the fog hid the entire top half of the ship, and the ship

disappeared into the fog within a few seconds after the “Up Ship” signal

was given. What few delays appear on the record were due to waiting for

connecting airplanes to arrive with the latest European mail for the

Americas.

 

So far the use of masts had been entirely a matter for the large rigid

airships. The Army did the first development work on high and low masts

for its smaller ships at Scott Field, as well as a landing wheel for

them to ride on. A situation at Akron started experimentation along a

different line. At Goodyear’s Wingfoot Lake Field, Mr. Litchfield

frowned over the expense of having a considerable crew on hand to land

and launch the blimps, with little to do after the ship was in the air.

To an Army or Navy post, with plenty of men in training, this surplus of

men was no difficulty, but any private corporation operating passenger

airship lines would find the expense burdensome.

 

[Illustration: The Navy L-2, one of the first ships under the

expanded program, lands at Wingfoot Lake, Akron, is walked to the

mooring mast.]

 

[Illustration: Close-up view of engine and cowling, and swiveled

landing wheel.]

 

[Illustration: With a drogue or sea anchor to hold the airship

steady, supplies or personnel may be taken aboard at sea. (U. S.

Navy photo)]

 

[Illustration: A newly-hatched airship breaks its shell at Akron,

will try its wings then join the Navy.]

 

He put the question to his men in 1930, offering cash prizes for the

best solution. Out of many ideas, one clear-cut line of progress

appeared. This was to make the ground crew truck a maneuvering base,

with a mast on top, which could be folded down when not in use. The

truck then could not only hold the ship on the ground, but guide it in

and out of the hangar with more security than by using a large number of

men. Extra wheels mounted on outriggers kept the truck from being turned

over by side gusts. In succeeding years the ground crew truck became a

traveling mooring point which could follow the ship across country, give

it anchorage when night fell, and at the same time act as a traveling

supply depot, machine shop, radio cabin, and crew quarters.

 

A portable mast, built in sections, high enough for ships to mast at the

nose, was the next step. It could be set up on an hour’s notice,

anchored by guy wires and screw stakes for more extended operations.

Gradually the airship became independent of the hangar, came to use it

only for overhaul and the purification of its helium gas. The blimp

could be fueled and serviced completely in the open.

 

Lacking a dock in San Francisco, at the time of the Exposition in 1939,

the Goodyear blimp Volunteer moved up from Los Angeles, based on a mast

for five months. The only time it sought shelter was when a splinter

from the propeller pierced the bag, causing a leak. The ship flew 60

miles down the bay to the Navy base at Sunnyvale, like a boy coming in

from play to have a splinter removed from his finger, went back again,

didn’t even stay over night.

 

In the winter of 1940-41 the “Reliance” which had been spending its

winters in Miami, using a wartime Navy hangar which the city had moved

up from Key West, found that building commandeered for defense work. So

a mast was set up on the Causeway, and the ship operated with no other

home than that for six months, saw no shelter from the time it left

Wingfoot Lake in early December till it returned at the end of May.

 

The Navy had a different problem as it moved into the non-rigid picture

in the early 1930’s. Its problem was only incidentally to operate away

from its base at Lakehurst. Ships were getting larger in size, and masts

were needed where they could be moored outdoors, or taken in and out of

the hangar. The solution was a smaller replica of the rigid airship’s

“Iron Horse” except that it moved on large rubber tires, and was towed

in and out by tractor, rather than carrying its own power plant.

 

A portable mast was also developed for the Navy blimps, with a special

car to haul it around. This mast could be sent to Parris Island or some

point in New England, ahead of time, set up and used as a temporary base

for radio calibrating or other missions.

 

Navy ships basing at Lakehurst have operated for weeks at a time along

the coast as far north as Bath, Maine, and as far south as the

Carolinas, with a portable mast as headquarters.

 

Utilization of the mast principle by non-rigid airships not only greatly

increased their radius of operation, and cut down landing crews, but

increased the number of operating days per month.

 

Pilots of early airplanes used to go out on the airport, hold up a

handkerchief, and if it fluttered, conclude it was too windy to fly. So

early airship pilots, with anemometers on the roof of the hangar and at

points over the field, judged it too risky to take the ships out if the

wind was higher than four or five miles an hour, and then only if it was

down-hangar in direction.

 

Modern airships lose few flying days because it is too windy to go out.

Under war conditions, when risks must be taken, which need not be taken

for passenger or training flights, very few days would be wasted if

there is military necessity for it.

 

Navy non-rigids miss few rendezvous with the fleet in exercises out of

Lakehurst, regardless of the weather outside.

 

If the portable mast revolutionized airship operations over land,

experiments started by the Navy in 1938-39, largely under the direction

of Lt. C. S. Rounds, promise to be just as important in over-water

operations. These showed that the airship could pick up ballast from the

ocean, could get fuel from a passing ship, could change crews at sea.

 

Ballast is important to a vehicle which growing continuously lighter as

it uses up fuel, must still be kept in equilibrium. Transoceanic

Zeppelins, using hydrogen, had to fly high enough to “blow off” the

surplus gas once or twice during a trip to compensate for the ship

growing lighter. But hydrogen was cheap, and could be manufactured as

needed. American ships could not afford to waste helium, which was a

natural resource. Army and Navy engineers had worked on this, and

equipment developed for the Akron and Macon to condense the gases from

the burned fuel was able to recover more than 100 pounds of water

ballast for every 100 pounds of fuel used.

 

The blimps didn’t use these since they ordinarily would not be out for

more than a day at a time, still a ready source of ballast would make it

unnecessary to valve helium on long flights.

 

Ironically enough a whole ocean full of ballast lay below seagoing

airships, but no practical method had been devised to take the sea water

aboard until the Navy tackled the problem in 1938.

 

That problem may be visualized in the obvious difficulty of maintaining

physical contact between an airship and a surface ship. The two move in

different media, one influenced mostly by the waves, the other mostly by

the wind. The surface ship is moving up and down, the airship subject to

gusts which might break the contact or thrust it violently against the

masts or superstructure of the surface ship. Servicing has been done

under favorable circumstances, but could not be relied on as standard

procedure.

 

The solution reached was this. The pilot swings his ship down to within

100 or 150 feet of the water, lowers a hose with a small bronze scoop,

not much wider than the hose, so as to lessen the drag.

 

Twenty-five feet up from the scoop is a streamlined cylinder, blimp

shaped, carrying a small electric pump. This cylinder, nicknamed the

“fish”, has tail fins to keep it from spinning, and skims along the

surface or jumps out like a porpoise, but the scoop is far enough behind

and heavy enough to trail easily beneath the surface, stays directly in

the ship’s wake, continues without interruption to pick up ballast for

the airship above.

 

The whole gear weighs slightly more than 100 pounds, can pick up water

at cruising speed, can function in rough water or smooth. The Navy J-4,

chiefly used in these experiments, normally consumes 500 pounds of fuel

in five hours of flying at cruising speed. It was able to pick up that

much water ballast in seven minutes.

 

The next step was to enable an airship to obtain fuel from a tanker or

other ship without physical contact or advance arrangements—even from a

passing merchantman. The pilot asks by radio or voice whether the

surface ship can spare some gasoline, and on an affirmative answer,

lowers or drops on his deck two rubberized fabric spheres connected to

each other by 14 feet of rope—also a note of instructions. The smaller

sphere is an ordinary air-filled buoy, the larger, about three feet in

diameter when filled, is the fuel bag. The surface ship fills the fuel

bag, then drops both bags overboard, being careful only that they do not

get tangled up. Then the airship flies over the two bags, drops a hook

between them, hauls away, pumps the gasoline into its tanks.

 

The third device permits an airship to anchor in the open sea near a

surface ship to transfer crews or take on fuel and supplies. The anchor

is a cone-shaped rubberized fabric bag, ten feet long, with a diameter

of 2½ feet at the top. It is lowered 50 feet below the airship by two

cables connected with each other by rungs to form a ladder. Half of the

cables’ length is made up of heavy exerciser cord to dampen the effect

of wave movements. On top the cone is a wire mesh cover which allows the

water to pass through, and is strong enough to act as a platform,

supporting a man.

 

As the cone fills up the airship drops ballast till its “mooring mast”

is half submerged. The principle of the drag rope comes into play—if the

airship starts to rise it finds itself lifting an increasingly heavier

load, counteracting the rising tendency. If it starts to settle down

toward the water, the load is correspondingly lessened and the ship

grows lighter. The result is that the airship is held highly stable,

even in a rough sea. The surface ship then sends a small boat alongside

and dispatches the relief crew members or supplies, them up and down the

ladder, or uses a winch, the platform atop the anchor serving as the

operating base. This system also permits the moving of a sick passenger

ashore, or the rescue of a man overboard.

 

When the airship is ready to leave its anchorage, the cone is tipped by

a line attached to the bottom, spilling the water, and hauled aboard.

The servicing ship need carry no special equipment. The weight of cone

and ladder is negligible.

 

By being able to pick up ballast and borrow fuel from a passing ship,

(neither airship nor surface ship need slow down for the fuel exchange

if going in the same direction) the airship greatly increases its radius

of operations.

 

The advantage of being able to change crews at sea may not be quite as

clear. This, however, grows out of the fact that today’s non-rigid

airship has greater endurance than the crew which flies it. An

anti-submarine, anti-mine patrol calls for constant alertness. Reduction

of vibration and noise, the use of closed cars instead of open cockpits

has lessened fatigue, enabling men to remain on duty over longer periods

than before. But obviously there are limits.

 

The Navy is conservative in estimating how long its new “K” ships may

stay out without refueling. Weather and the nature of the mission will

have some bearing on that, but if we assume a cruise of 48, 60 or even

72 hours which might be done under favorable conditions and idling the

motors, we still cannot expect a crew of men to remain vigilant and

alert for that length of time.

 

Extra men for relief watches can be carried only at the expense of the

fuel load. However, if a fresh crew could be sent aboard every 12 hours

from a nearby surface ship, along with fuel, ballast and supplies, the

blimps might operate for extended periods.