N1 was leading edge technology in 1926 and it was complicated. On the North Pole flight 16 men were aboard, and 13 of them were required to fly and navigate Norge. The Norwegians had a relatively short time to learn the necessary skills and establish good working relationships with their Italian counterparts. They attended a brief ground school before the flying started, and had to absorb some fundamental concepts. A key concept for them to understand was that an airship is a steerable balloon and behaves like one. If all engines are stopped it has to be flown like a balloon. To go up ballast is dropped (sand or water with anti-freeze in it). To descend gas has to be valved. Buoyancy will change with changes of temperature. If the gas is warmed by the sun it will expand and create more lift, and the balloon or airship will rise. If the gas cools the reverse happens. A power-off landing involves careful valving of gas. Once on the ground no one leaves the airship or balloon without orders. If someone jumps out of a balloon’s basket it makes it light and it will lift off. The same applies to an airship. If a strong wind is blowing, a rip panel (or panels) will be torn out to dump the gas and the lift. Until this has been done the envelope acts like a sail and drags the balloon or airship downwind.
Another key concept was that a balloon (or an airship with the engines stopped) drifts with the wind. There is no relative wind past the envelope. A passenger in a balloon flying in a gale can read an open newspaper in the basket because of this fact. A free ballooning airship or a balloon cannot be steered. All that can be done is to rise or descend into winds, which may differ in strength and direction with altitude.
The training flights started with the engines of N1 being warmed up in the hangar. The pilot would “ballast up,” a misleading term meaning “check the buoyancy.” Ballast would be loaded or unloaded to leave the airship in about neutral buoyancy. Then the ground crew of 200 would hold on to the control car and rear engine car, and to ropes hanging down from the full length of the airship on both sides. They would need to exert a slight up or down force to stop it rising or falling. An officer with a megaphone would shout orders, and the airship would be walked out onto the airfield. In light winds this was not a problem, but things could get tricky. A gusty wind, or one blowing at an angle to the axis of the hangar, required the ground crew to use their strength and weight in an intelligent and coordinated way. An airship on the ground in a gusty wind would drag hundreds of men back and forward and from side to side.
If the ship was light some of the men might be lifted into the air, and sometimes men holding on too long would fall from high enough to be killed or injured; if and when to let go was a matter of fine judgement. If the cross wind was too strong the airship stayed in the hangar.
Just before take-off the captain checked buoyancy. If the airship was heavy, about 100 kg of ballast was dropped to make it light. The captain would take off by leaning out of the control car door and ordering “let go.” N1 would slowly rise into the air while the mechanics in the engine cars started the three Maybach engines. After that the captain aimed to make the flight without dropping ballast to climb and without valving gas to descend. He would climb and descend dynamically with the up or down elevator.
For a short flight about 80 percent of the volume of the envelope was taken up with hydrogen, and 20 percent with air in fabric containers inside the envelope called ballonets. As the airship climbed the pressure dropped, and the hydrogen expanded and squeezed the ballonets so the air was forced out of them and out into the free air. When the airship descended, and increasing pressure contracted the hydrogen, air was admitted into the ballonets. That way the total volume was always 100 percent. The reason for doing this was that N1 was a “pressure airship” and needed to have its envelope 100 percent full, and at a pressure greater than the atmospheric pressure to keep its shape. If the pressure fell too low, and the envelope became less than 100 percent full, the airship would lose its shape and go out of control. N1 was a semi-rigid with a steel tube keel along its underside, and this helped it to retain its shape, but managing gas volume and pressure was essential throughout a flight.
The airship was flown from the control car located under the envelope toward the nose. In it were the captain, rudder coxswain, elevator coxswain, navigator, and radio operators in their separate cubicles. The rudder coxswain stood holding the rudder wheel in the front of the control gondola. The compass was sluggish in its response to changes of heading, so the rudder-man picked a point on the landscape or cloudscape to steer toward. He would note the compass heading from time to time after the compass settled. The elevator coxswain stood on the starboard side of the gondola holding the elevator wheel and facing out to that side. The cruising height was about 1,000 ft., and this height was maintained by turning the wheel clockwise (up elevator producing a pitch up and a gain of height) or counter-clockwise (down elevator producing a pitch down and a loss of height). In front of the elevator-man were the wires controlling the gas valves on top of the airship. On the port side of the control car the captain stood keeping a general eye on the flight. The engine telegraphs were located above him. The captain could order each engine started or stopped and the rpm to be set when it was running. The engines (or one of them) could be run in reverse, and this was sometimes done when landing. The radio room was partitioned off in the rear of the gondola. The airship had been fitted with aerials built on to the envelope and with an aerial with a weight on its end that trailed about 200 ft. from the control car in flight. It was wound in for landing. In poor visibility a crew member might be instructed to watch the aerial and yell out if it twitched on contact with the surface. On long flights a radio operator and a technician were aboard. The radio operator sent position reports and received weather information from as many stations as possible. All flight operations are weather dependent, airship operations more than most. For this reason a meteorologist was to be carried who would update his forecasts as information came in. There was a toilet, and a ladder led from this space to the keel. The radio was also used to send news reports from the journalist on board to newspapers that provided the expedition with financial support. Another use for the radio was to provide directional bearings to radio stations. These were handed to the navigator. The navigator worked at his chart table with the tools of his trade, including: charts, sextants, chronometers, parallel rulers, pencils, drift and groundspeed meters, magnetic compasses, sun compass, logbooks, and sight reduction tables. On a long flight the navigator was the busiest member of the crew and had very little time to relax.
The keel was a triangular structure of tubular steel covered in doped fabric. It was made of sections hinged to allow some flexing under flight loads. The keel was where the petrol tanks, oil tanks, survival gear, tool boxes, and ropes and cables for ground handling were stowed. Walkways proved access from the keel to the side engines, and a ladder led down from the aft section of the keel to the rear engine. Mechanics were in each engine car when it was running or being repaired. Gustav S. Amundsen observed that the noise made conversation difficult, and there was a strong draft through the car with the engine running and the radiator shutters, at the front, open. Right forward there was a ladder for use by a rigger who would climb out and up, over the nose, and on to the top of the envelope to check the gas valves. The envelope was divided into 10 compartments for the hydrogen. Each compartment had its own group of valves on top of the envelope. The valves could be operated manually from the control car, or automatically when gas pressure exceeded a set value. Each group had a cover over it to prevent ice forming on the valves. If ice formed on a valve it might jam open or closed with drastic results. Also in the keel were three coiled ropes for hauling down, and a fourth that was under the control of the captain and was used to shackle to the mooring mast cable if the airship was to be docked to it. In the keel there were 32 tanks hung up in the gang-way in pairs. For the legs of the positioning flight to Svalbard the front and rear pairs contained water ballast, and the remaining 28 were filled with petrol. If maxi
mum range was required all 32 were filled with petrol.
The airship was slightly light at take-off, but as the airship picked up speed the slipstream cooled the gas making the ship heavy. The captain would order 3° to 6° of up elevator to produce dynamic lift. The sum total of static lift from the gas, and dynamic lift from the airflow over the hull equals the weight of the ship and it maintains height. This kind of adjustment continued throughout the flight as the static lift changed with changes in temperature and volume of the hydrogen gas. If the airship is light, down elevator produces negative dynamic lift off the hull, which is subtracted from the static lift, and the airship again maintains height. Maintaining height in this way was standard practice, but did increase the total drag of the airship, and the cruising speed was reduced, as was the range.
Norge in flight. The Norwegian flag flies from the tail and the Italian from a weighted line below the control car.
On a long flight the crew members spent some time on and off watch. When off watch they could sleep if conditions permitted it. There were no bunks or cabins on Norge, and sleep had to be sought on the narrow gangway in the keel with a lifebelt for a pillow and only a raincoat for bedding. The gangway was constantly in use and sleep was fitful. The engineers monitored the engines in flight. In the keel, crew members managed the petrol and oil so that each engine received enough, and so that the fore and aft trim of the airship stayed about neutral.
Before landing the captain would check the buoyancy by stopping engines and noting if the airship rose or fell. A skilled coxswain could tell a lot about the buoyancy from the way the airship responded to the elevator wheel, but it was safest to stop engines and let the variometer tell its story. Neutral buoyancy was ideal, as the landing could take place without dropping ballast or venting hydrogen. If the wind was too strong or gusty for a landing, the airship would stay airborne at low power until the wind dropped. If the wind was okay for a landing, but too strong to be walked into the hangar, the ground crew would have to wait for a lull and hold on to the ship out on the airfield until one came along.
On the flight to Svalbard, the airship would use the mooring masts designed by Nobile and built at Oslo, Vadsø, and Kings Bay. These high masts had been developed by Major Scott in Great Britain, and studied by Nobile on a visit to that country. Their purpose was to enable the airship to be refueled, resupplied, and maintained if there was no hangar or if the wind strength and direction prevented the airship from entering the hangar. A mast had been constructed at Ciampino so the crew of N1 could train on it. Nobile had to train himself and the crew because the Ciampino mast was the first to be built in Italy, and he had no experience of flying to and from them.
The masts were “high” masts about 130 ft. tall. Ground crew and airship crews had to climb and descend a series of ladders to get up and down them. The technique for mooring to the mast was for a cable from the winch at the base of the mast to be led up to the top, through a swivel arm, and out through the hollow center of the cone. From there it was dropped to the ground and hauled about 300 m downwind of the mast. The airship approached the mast from the downwind side, at about twice the height of the mast. The engines could be reversed and this would be done to take the speed off the airship or if it looked like over-running the mast. A wire was dropped from the center of the reinforced nose of the airship. The airship then dropped some ballast forward to compensate for the extra weight of the cable from the mast, which it must pick up. The cables were shackled together, and the airship was slowly winched toward the mast until the point of the reinforced nose of N1 fitted snugly into the cone at the top of the swivel arm. The nose was then locked to the cone, and a rope was attached to the nose to strengthen the connection. A gangway was lowered from the nose of the airship, and connections for gas, petrol, and water were made. N1 was free to swivel through 360° while moored, so it always pointed into wind. The docking cable was released and coiled in the bow of the airship. On a training flight the crew stayed on board until the airship undocked. On the flight to Svalbard part of the crew could disembark but some of the crew remained aboard throughout the stay because the ship needed to be “flown” while at the mast.
To undock the order “unhook” was given and the officer in the tower complied. The next order was “slip the rope” and the hemp rope holding the nose was slowly paid out. The captain checked that the ship was slightly lighter than air then ordered “cut” and the rope was severed and N1 floated away and upwards from the mast and the engines were started. Captain and crew used the Ciampino mast on a number of the training flights.
When the airship was walked into its hangar it was normal airship practice to take on ballast before each passenger disembarked. In the hangar the airship had enough ballast aboard to make it slightly heavy and it was tied down. An airship always had a crew member or members standing by to monitor its buoyancy.
The Norwegian flag flies from the tail of Norge.
On a long flight the airship would take-off 100 percent full of gas and operate at an altitude of about 1,000 ft. for as long as it could. If they were forced to climb the airship would reach “pressure height.” Above pressure height further gas would expand and increase pressure to the point where gas had to be valved off to avoid splitting the envelope. The need to avoid going over pressure height meant that airships usually had to go around rather than over mountains. This was a significant limitation on where they could go and added to the distance to be flown.
Airships were every bit as complicated as aeroplanes, possibly more so in the 1920s. The captains and crews had to be well trained and perform their duties to a consistently high standard. Flight operations required a well thought out flight plan and great attention to detail. With the large aircrews, ground crews and maintenance crews, hangars, masts, workshops, and gas-generating plants, airships were capital-and labor-intensive to operate.
As the hand-over date, March 29, 1926, got closer, the Norwegians and Italians were shaking down into a good crew.
Chapter Eleven
Positioning Flight
Ciampino–Pulham–Oslo–Gatchina–Vadsø–Kings Bay April 10, 1926–May 7, 1926
As soon as the handing over ceremony was complete, Amundsen and Ellsworth set off for Norway by rail and ship. They would join Norge at Kings Bay and be aboard for the great flight from there to the North Pole and across the Arctic Ocean to Alaska.
For the flight to the Pole and beyond to take place the Norge had to be delivered to Kings Bay. The airship was too complex to dismantle at Ciampino, ship to Svalbard, and reassemble at Kings Bay. The only practical way to get the airship to its base was to fly it there. The flight was to be in stages. From Ciampino the ship would fly to Pulham in Norfolk, in the southeast of England. The Royal Air Force had an airship base there with two hangars, an airship mast and supplies of fuel, oil, ballast, and food. A large ground crew could be summoned to walk the Norge in and out of its hangar, and there were facilities for the repair of airships and their engines. The radio station at Pulham provided communications and navigational assistance with its direction finding capability. The next leg of the flight would be from Pulham across the North Sea to the mast at Oslo to give the inhabitants of the Norwegian capital a view of the ship. The expedition had gained permission from the Soviet Union to use the facilities at Gatchina near Leningrad (now known by its old name of St. Petersburg), and the next leg was Oslo-Gatchina. Gatchina was chosen because it had the northern-most airship hangar. The plan was to hangar Norge until good weather was forecast for the balance of the flight and Vadsø and Kings Bay were ready for Norge. From Gatchina the flight was across Finland and the Baltic Sea to Vadsø in the far north of Norway. The final leg was from Vadsø across the Barents Sea, past Bear Island to Ny-Ålesund on the southern shore of Kings Bay on the Island of Spitsbergen where a complete airship base was waiting for them.
On April 6, 1926, the crew were notified that they would be departing at 10:00 on the following day. A large cro
wd, including Norwegians living in Rome, came to Ciampino to see them off. Also there was Mussolini, with a bandage on his nose; he had been nicked by a bullet in an assassination attempt the previous day. Luggage was weighed and loaded, flowers were presented, and goodbyes said. They waited for the start, but a bad forecast delayed them. Bags were unloaded and the crew returned to Rome. Weight and lift are always on the mind of the captain of an airship, and Nobile was no exception. He told the Norwegians that their baggage was too heavy, and there was a negotiation that ended with the Norwegians allowed to carry one very small bag each. Just before the flight a case containing specially made flying suits arrived for the Norwegians. The suits had been made-to-measure in Berlin for each of the Norwegians. They were of a windproof material and lined with lambswool. Each suit also came with a helmet and gloves made of the same material. The case was taken away and was next seen in Spitsbergen. The Norwegians would have to make a flight to the Arctic in the casual clothes that they had worn to the airfield. Finally, on April 10, 1926, and before a smaller crowd, they departed. At 09:00, Nobile ordered the Norge to be walked out of its hangar at Ciampino. Watching were representatives of the Norwegian Aero Club, the Norwegian Legation, and many of the men who had built Norge. At 09:30, Nobile lent out of the control car door and ordered “let go.” Nobile was using the normal technique for launching a large airship, and had adjusted the ballast so that the airship was several hundred pounds lighter and the Norge slowly rose into the air while the mechanics in the engine cars started the three Maybach engines. The Norwegian flag flew from the tail cone, and the Italian flag from a weighted line below the control car. The route chosen allowed the airship to avoid high ground. The shortest route to Pulham (a great circle) would have taken the airship across the Alps, but this had to be avoided to conserve gas and therefore lift. This was because a climb would have meant that gas would have to be valved off to avoid the expanding gas tearing the envelope open. The route was an indirect one that took the airship northwest to the southern coast of France before turning on track for Pulham. Nobile flew across Rome, then west toward the Tyrrhenian and Ligurian Seas and past the island of Corsica. He had intended to follow the Rhône up the middle of France, but the forecast from Finn Malmgren, the meteorologist, suggested that an alternative route would be wise. At 18:00, they crossed the coast of the south of France. The airship flew across southwestern France and turned northward near Bordeaux. If they had encountered strong head winds, they could have landed at the airship base at Rochefort to refuel.
From Pole to Pole Page 13