ZR-1 introduced novel problems in hull-strength calculations (a Zeppelin secret), shop practice, and for the erection of very large aircraft. Duralumin—a lightweight German-made alloy—was a new art in America. Development of a suitable U.S.-produced alloy was the product of a cooperative effort that by about 1921 realized Zeppelin-type components of ample strength and lightness. Fabrication work was done at the Naval Aircraft Factory in Philadelphia, with the parts shipped to Lakehurst. The experience gained with aluminum was promptly applied to airplanes. C. E. Rosendahl Collection, HOAC/University of Texas
Ground school opened on 15 March 1923. Commander McCrary set the tone and outlined his personal views relative to the assignment before them all:
The purpose of this lecture is to start a ground school course of instruction for the personnel detailed as crews for the ZR-1. We are very much handicapped in this work in that none of the officers concerned have had sufficient experience to qualify as an authority on the subject and it may surprise some of you to find that you have been detailed to give lectures on subjects of which you have little if any previous knowledge. We have Captain [Anton] Heinen with us, who has had a large experience in handling dirigibles in Germany; it would however be impossible for Captain Heinen alone to carry out this course of instruction in the limited time, so we will have to utilize his services in an advisory capacity and as the flight instructor when flights are begun.4
ZR-1, June 1923. The outer cover of “doped” cotton fabric is being laced to the 680-foot airframe—the panels tailored to the ship’s lines. At left, a gas cell lies on the deck. The approximate cost for each of these fragile chambers was about $18,000. Installation and inflation required “care, experience and patience, but one which was truly rewarding as one watched each of the huge cells fill out to become a key lifting element of the airship.” Note the railway spur through the room—berthing space for two ZRs. R. F. Burd Jr.
The proposed syllabus was divided into a number of areas, with specific officers from this inaugural class assigned to prepare both lectures and the practical work to follow. Many of topics became an integral component of LTA training: navigation; “aeronautical seamanship” (aerology, ground handling, aerostatics, and aerodynamics); rigid airship design and structure; airship maintenance; power plants; communications; helium; and, of course, the actual flight training. Instruction of the enlisted personnel at this point consisted solely of practical instruction, except for being present at selected lectures given to the officer complement.
Keel of ZR-1. This “catwalk” supported concentrated weights and formed a corridor through the hull. Note the lattice-type girders, wire bracing, and the aluminum fuel tanks. Extending bow to stern, this main avenue of communications housed fuel, oil, water ballast, food lockers, bunks, living quarters, head, and access to the control car (bridge) and engine cars. R. F. Burd Jr.
As yet, there were no ships to fly. Although McCrary had considered it “essential” to have at least one small airship in inventory for training, none were made available for the ZR-1 trainees until J-1 made her first Lakehurst flight in May 1924. But balloons were available. Practical training in aerostatics was provided by taking the men up in kite (or captive) balloons, at least one of which was selected for shipment to Lakehurst from the Rockaway New York air station in August 1921. And that December, less than three months before the course began, the Bureau of Aeronautics (BuAer) approved the shipment of three free balloons to Lakehurst for training.
A free balloon (ZF) lifting off. An airship is a balloon with engines, exquisitely sensitive to atmospheric conditions that must be anticipated. If control is lost, the ship reverts to balloon. Thus, aerostatics was practiced using balloons. Note the dropped ballast, sand trough on the basket’s rim (disposable ballast), and drag rope (left), an “automatic ballast” on approach for landing. Lt. Cdr. L. E. Schellberg, USN (Ret.)
Follow for a moment Lieutenant Rosendahl’s LTA instruction in this formative period. Less than two weeks after reporting on board, he made his inaugural flight in a lighter-than-air craft, a kite balloon (No. A 6109) on 19 April 1923. Commander Weyerbacher was pilot. Ten kite up-and-downs were logged that day by the young officer, for a total time aloft of one hour and eleven minutes. Duration of each (tethered) flight: from five to nine minutes. On 4 May, Rosendahl was one of four passengers on a free balloon for another three hours and twenty-five minutes before touchdown near Whitesville, New Jersey. The other officer students were Lt. Herbert V. Wiley and Lt. Earle H. Kincaid. The future admiral’s second free balloon was not logged until August. By the date of his first flight aboard ZR-1, on 12 September, Lieutenant Rosendahl had accumulated a total flight time of eleven hours and forty-three minutes—all in balloons. No blimp time had yet been logged. He would not solo in a free balloon until 10 November. Finally, on 21 November, Rosendahl was directed to appear before a board to examine candidates for designation as naval aviator (airship). The next day, he was so designated, receiving aviator number 3174.5
A pigeon is “shoved off” to report landing. The basket and gear were manhandled onto a chase truck for return to Lakehurst. The training syllabus required seven flights for officers, three for enlisted personnel. Ballooning was a class in applied meteorology. Set against the backdrop of sky, a student’s observations were more enduring than any textbook explanation. Arnold/Author
On 1 February 1923 the hull structure of ZR-1 was virtually complete. The outer cover was now applied. Made of high-grade cotton fabric, the cover panels were laced tightly into place over the entire hull and given several coats of dope, which shrunk the material tight against the framework. Sealing strips doped into place between the individual panels provided a smooth outer surface over the joints and continuity to the ship’s exterior surface. The final coat was mixed with aluminum powder to provide a smooth, weather-resistant skin that also reflected the sun’s heat away from the lifting gas.
General outfitting of the airship began at this time: the ballast bags spaced along the keelway, her control wires, fuel and water lines, pumps, and the hundreds of items of equipment needed to operate the ship were installed. The control car and engine gondolas also were nearing completion. The six engines were suspended outside and away from the hull in separate pods. The aft power car and the control car were equipped with handling rails for ground crews, which allowed the aircraft to rest on the ground at these two points. The forward car of ZR-1 was suspended from the hull by struts and cables; subsequent ships had theirs built up against the hull. A sixth engine was located in its own car immediately behind the control car, but this power plant was later removed.
An airship’s control car was the nerve center, or “bridge,” of the ship:
In the control car are located all of the instruments necessary to navigate the aircraft as well as those required to fly it as an airship. In the extreme forward section on the center line is located the rudder control, in front of which will be found the compass. On the port side is located the elevator control mechanism and the instrument board upon which will be found an inclinometer, an altimeter and barometer, a gas-pressure alarm, and a variometer (rate-of-climb meter). Here will also be found the gas and air thermometers or “superheat” meters.
Immediately above this station is located the minor control box . . . [which] contains the necessary pulls for operating the maneuvering [gas release] valves and the various