Maintaining Sub Killers

by Lt Comdr Robert E Huse, USNR
Asst Assembly & Repair Officer,
Naval Air Station, Richmond, FL

First Article Ever Published on Maintenance and Repair of Our Navy's Blimps

These craft, key weapons in the successful fight against the submarine menace, are writing one of the truly great stories of the war.

This initial detailed revelation of blimp maintenance was written under the direction of Rear Adm Charles E Rosendahl, USN, Chief LTA Training Command; Capt Chas J Maguire, USN; Capt Frank L Warden, USN, CO NAS, Richmond; and Lt Comdr J H Greenwald, USNR, A & R 0fficer, NAS, Richmond.

Graceful and impressive, the great silver airships of the US Navy soar overhead. They are doing their part in winning the battle against the Axis submarines, they are effecting rescues both at sea and on land, and they are carrying out special missions and assignments in connection with their duties as parts and parcels of the United States Fleets.

Day in and day out, and night in and night out, the big helium-filled blimps, with their heroic crews, lift into the skies, unheralded and unsung. Blimps are credited with having performed invaluable services in convoy work; these airships are held in high regard by the Navy and by their companions of the airlanes, the heavier-than-air units. Complex and interesting is the behind-the-scenes picture of the blimps — the problems of assembly and repair — their overhaul, upkeep, and servicing. Just as there must be at least ten men behind every heavier-than-air pilot, there must be as many, if not more, behind every pilot who flies a blimp. "A & R", the lighter-than-air assembly and repair department, is a closely knit, highly efficient, expertly staffed organization, which has been laboring 24 hr a day — even as the airships themselves patrolled the skies — to "keep 'em up."

Typical is the A & R Department at the Navy's big new overhaul and operation base at Richmond, FL. In mid-September, 1942, the Naval Air Station at Richmond was officially commissioned. It was a Naval Air Station in name only, since the 2,100 acres of scrub pine were just another spot in the edge of the Everglades. A landing mat and two runways were hacked out of the wilderness, and the mat was. surfaced with easily obtainable coral rock. Even before this was completed, the first airship was ferried in from Lakehurst, NJ. The newly commissioned squadron began operating, making the most of the makeshift facilities available.

In the early days of the station, airships were "masted out" at all times when not actually flying. Handicapped by lack of regular shop facilities, expedient and novel methods were employed to accomplish upkeep and maintenance work while the airships were riding unsheltered to their masts.

A mast watch officer and two enlisted men stayed with each ship, adjusting pressure and ballast as the helium in the large envelopes reacted to the constantly changing atmospheric conditions caused by sunshine, rain, and fluctuating barometric pressures and air temperatures. One of the huge tripod masts was fitted with a bunk-room in which the mast watchers, while immediately available for a call, took turns catching forty winks between watches.

With the squadron thus established and operating, work was begun on the first of the three immense wooden hangars to be built. The end was many months away, but the skeleton of a department had been created. An A & R officer was ordered to the station, and a staff of officers, enlisted men, and civilian specialists arr to form the nucleus of the repair force being assembled. Shops were outlined, equipment ordered, and all of the intricacies of the overhaul and repair of the K-ships were analyzed.

The spirit of "can do" was instilled from the beginning. As the one and only function of the department was to "keep 'em flying," innumerable emergency repairs had to be accomplished at any hour required. Routine engine changes had never before been effected without the protection and convenience of a hangar, but ten Pratt & Whitney 1340 AN-2 aircraft engines weighing close to 1,000 lb were changed while ships were masted outside.

At first, one engine job per night was all that could be done. But, saying "can do," a unique outside work stand was constructed. With this stand attached to the ship itself, it was finally possible to remove and replace both engines of an airship, run them in, and have the ship ready for a 0500 takeoff (a 5 AM flight). Almost every type of emergency repair was handled — including damaged landing wheels, broken tail wheels, and scraped tail fins — in addition to the regular routine checks by the organized and trained lighter-than-air specialists of the night check crews.

In June, 1943, the structure of the No 1 Hangar, A & R's home, was completed. Then hangar operations were begun, although machinery and shop equipment were far from complete. The personnel problem was a difficult one. Although every man assigned to A & R possessed an attitude of willingness, interest, and enthusiasm, the majority lacked previous experience or training in airship work. However, this newly formed green crew "turned to" with a will for accomplishment, gaining in experience as interim overhaul of K-ships was begun.

Interim overhauls, scheduled after approximately 1,000 hr of flight time, require 10 to 14 days to accomplish. As work began, groups of Navy and civilian specialists literally swarmed over all parts of the ship.

Almost all removable gear is taken from the ship and removed to shops for reconditioning and repair. Radio, special equipment, life jackets and rafts, instruments, major and minor controls, chairs, engines, and accessories, fuel tanks and gauges — all are taken to shops having cognizance over them.

The envelope is plumb-bobbed to determine its alignment and whether or not any distortion has taken place. If any misalignment is noted, fins are reset to attain the proper flying characteristics. "High-men" work up in boatswains' chairs rigged to the 180-ft overhead of the hangar. They inspect the top of the envelopes, minutely noting any defects or unusual wear as well as retensioning all fin brace wires. A nose crew removes and reconditions the long slender nose battens, and riggers and cable men disassemble the nose mooring assembly.

Bit by bit, the airship is completely torn down, and all but the car and bag itself is sent to one or more of the 20 shops that are part of A & R. After necessary checking and servicing, the various parts are returned to the ship and reconstruction is begun. When painting and Plexiglas work is completed, the various parts of the ship are reassembled and the finished product takes form. Finally, after completion of all the required work, the dock trials of the ship are begun. Valves are tested for proper calibration, engines are run in, fuel, oil, and electrical systems are checked. Then expert inspectors finally pronounce the ship ready for a test flight.

Although "lighter-than-air" is the designation for the large patrol blimps, supported by the static lift of the helium gas, actually they are usually flown initially heavy. Consequently, they must take off and sustain themselves in flight aided by the dynamic lift gained from their forward motion and airspeed. For this reason, the ship is ballasted with sand so it is about 1,500 lb heavy for its test hop. In the dim light of early morning, the test crew climbs aboard and the ship is undocked from the hangar by a ground handling party of 40 to 60 men.

After being spotted for the maximum length of field for the takeoff, the nose mooring pendant is released from the mast, the mast is hauled away, and the ship weighed-off. All lines slack, and with the car untouched, the trim of the ship is determined — nose heavy, tail heavy, or in trim. After the proper trim is obtained, the pilot clears his engines and signals to the ground handling officer for takeoff. Held into the wind by two short lines, the huge ship gradually picks up speed, and after a 500 to 1,000-ft run it is airborne.

Once in the air, the real tests begin. Rate of climb and descent at various engine speeds are tried to assure the strength and stability of the huge ship. Then speed trials are run: The amount of elevator needed to fly at constant altitude is noted for each speed range. Radio, special equipment, life jackets and raft, bomb releases, and machine guns are tested.

Next, the sand ballast is dumped out and the flight characteristics are carefully noted for all conditions, from the original degree of heaviness to equilibrium. Finally, with the ship in equilibrium and engines throttled all the way back, the trim of the ship is noted.

With all of this data assembled, the ship is flown back to the base and nosed down for a landing. With almost no forward speed, the ship hovers over the field, and the "long lines" are dropped to the ground handling party. The ship is hauled down, masted, then re-docked.

Once docked, the final touching-up is begun. Data collected on the test flight is analyzed — and the production superintendent, overhaul superintendent, and test pilot are informed as to changes or improvements to be made. Readjustment of control surfaces, retensioning of suspensions, or perhaps minor adjustments of controls or instruments, are decided upon and made. The ship is then fueled and turned over to the fly-away crew, perhaps to go to a close-by station or perhaps to make a series of long hops to a remote advance base. It may not be inside of a hangar again for months.

With the establishing of headquarters squadrons (blimphedrons), A & R is becoming more concerned with major overhauls, emergency repairs, and the manufacture of repair parts and changes, both for their own department and for hedrons.

Major overhauls, undertaken after approximately 3,000 hr of flight time, consist of a complete renovation of the whole ship, including removal of the envelope and installation of a new or reconditioned one. The preliminary work consists of laying out a 300' × 100' ground cloth on the deck. The ship is then spotted over the ground cloth on the deck and a huge net, 220' long and 200' wide, is spread over the inflated bag.

With the net secured, the car is then detached from the bag and wheeled away in a giant cradle. Sand bags, previously hung around the edges of the net, are gradually raised, diamond by diamond, on the net to force the bag down to the deck. The deflation lines are hooked up to the ship, and the helium is removed to storage in huge Horton spheres.

As the ship is deflated, the 550 sandbags are moved up the net, holding the partially deflated bag down. Finally, after several hours, the ship is completely deflated. The envelope must then be partially inflated with air so that riggers can go inside and remove valves.

The helium plant necessary to handle erection, deflation, and purging of K-type airships consists of four stage compressors, operating at 2,400 psi and a purification column at -192° C. The purification rate of the plant is 12,000 cu ft/hr. Storage of helium is in two banks of cylinders, each consisting of 85 units of 2'-dia and 80' long. Pressure in this stowage is 750 psi, with a total capacity of 2,000,000 cu ft.

Supply of helium is received at the station either by special railroad cars or high speed tractor trailers, and it is immediately placed in medium-pressure storage. An underground piping system is connected to all three hangars, and by use of Worthington compressors, ships are deflated at the rate of 48,000 cu ft/hr. This impure helium is then transferred to one of two Horton spheres with a capacity of 480,000 cu ft at 60 lb pressure. When these spheres are filled, the plant is started, and the accumulated gas is then purified and transferred to storage.

As the helium in the ships loses purity, it becomes necessary either to add pure helium or to purge the ships in order to attain maximum lift. This is accomplished by drawing the impure helium out of the low part of the envelope and replacing it at the same rate so that proper pressure is maintained. The impure helium is accumulated in the spheres and purified when capacity is reached.

For advanced bases, a portable purification unit has been developed by du Pont, using a continuous circulation and charcoal purification. The rate of 4,000 cu ft/hr is relatively slow, but if it is augmented by stowage, a sufficient supply can be built up to keep proper purities.

Once the car is secured the real work begins. The 24 slender wood nose battens are replaced on the nose and the nose spindle is installed. Electricians reinstall all leads for running and avigational lights and electrical instruments, and radio men install the two receivers and two transmitters and intercommunication equipment. Instrument men connect all the flight instruments, while mechanics install new engines and accessories. Other riggers are busy installing the horizontal and vertical tail surfaces and adjusting the many fin brace wires to their proper tensions.

At last the ship, completely reassembled and ready for 3,000 hr more of flying, is in line for dock trials and test flight.

Behind the schedule of these routine overhauls is a story of teamwork and industry. Sailors and civilians working side by side have made rigorous schedules routine. No less than 20 shops have handled this part of the overhaul, and all have had a heretofore impossible schedule to meet. Working together are these shops: Battery, cable, engine change, fabric, instrument, machine, metal, special equipment, dope, paint, sand blast, plating, propeller, electric, Lawrance, CO2, and riggers, together with the parachute loft, and the helium plant, manned by over 200 enlisted men and 100 civilians.

Besides these shops, various offices — planning and estimating, engineering, overhaul, production, inspection, safety, and personnel — have all contributed their efforts and skill to the completed ship.

Moreover, the workers in the drafting and blueprint section have added their efforts to effect changes and improvements, and a Goodyear field engineer has assisted with his knowledge and manufacturing experience in K-ships.

The work that shops, offices, and departments have accomplished in a major overhaul is divided into routine renovation, adjustment and replacement, and service changes. The latter are technical improvements or refinements in present equipment for more efficient operation and occasionally for removal of equipment not considered necessary when the weight involved is too great. These service changes, approved by the Bureau of Aeronautics, are serially numbered. Bureau changes usually are the result of RUDMs (Report of Unsatisfactory or Defective Material) which are submitted by squadrons, hedrons, or air stations.

Air stations are permitted to make local changes. These changes are circulated with descriptions and blueprint to all LTA activities, and adoption of them is optional. If the local changes are accepted as service changes, they become mandatory and A & R accomplishes them the next time the ship has hangar availability.

Manufacturing, which accounts for about 30% of A & R's work load, is a varied and specialized process. With shop equipment still far from complete and most material to be used requiring high priority, the mechanical processes are only half the battle. Job orders for one day often include manufacturing canvas bags for sand ballast, plating canteens for Marine landing forces, making homing loops for RDF sets, special clips for auxiliary brace wires, fittings for masts, an improvised bomb sight, and other widely varied items.

An improvised plating process using batteries as a source of current and two blowtorches for heat has made cadmium and chrome plating and anodizing possible.

When proper ladders for work on the sides of the ships and the lower fins could not be purchased, the carpenter shop undertook the task of manufacturing 20 55' ladders for new bases.

While carpenters made the actual ladders, the bases were shaped by metalsmiths, and salvage automobile wheels were mounted to give the necessary mobility. The units were completed for 50% of the expected cost and much quicker than they would have been available had they been purchased outside.

Richmond's organization is headed by an A & R officer, with an assistant in charge of administrative affairs. A production superintendent heads up all work, with subdivisions under him handled by an overhaul superintendent and an assistant, a shop superintendent, and a helium officer in charge of the helium plant. The finances and budgeting, as well as the necessary purchasing and planning, are under a planning and estimating officer. A maintenance officer and his assistant have charge of maintenance of the hangar, together with all of the shop equipment. Both civilian and enlisted personnel matters are managed by a personnel officer. Safety measures for all processes and personnel are administered by a safety officer.

Personnel at present numbers about 300. Of these, 200 are sailors and 100 civilians. Women are used extensively due to the manpower shortage. They have been found exceptionally capable in fabric and cable work. Almost all office work is handled by Civil Service women personnel.

The thirteen months just passed have seen a tremendous growth and a great deal of work done under trying conditions.

True, the next year will not be easy, but with equipment and material becoming available — plus the "can do" spirit — A & R can be depended upon to "keep 'em flying".

This article was originally published in the December, 1943, issue of Aviation magazine, vol 42, no 12, pp 128-135, 321, 323-324.
The original article includes 26 photos.
Photos credited as Official US Navy photos.

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