With the proliferation of airships in the 1632 universe, it is inevitable that there will be airship accidents, ranging from mere inconveniences to disastrous loss of the entire airship with loss of life.
And while this is a bad thing from the point of view of the characters, it is a good thing for readers and writers, since airship travel would get boring if it were 100% safe.
Airships in Canon
As of the time of writing, the following airships are in canon (country of origin and date of first reported flight in parentheses):
The Ottomans are known to have airships, but no details are given. In 1635, the Spanish were contemplating construction of a large hydrogen-lift rigid airship, the Sao Martinho, for use as part of the flota, but its fate is unknown.
The seriousness of an airship accident can range from trivial (delay in schedule, in-flight repair) to severe (loss of the airship and/or loss of life).
I find it productive to look at airship accidents from several perspectives: where the accident occurred (in ground handling, while cruising, while landing), what factors contributed to the failure, and what their effect on the airship’s condition were (loss of propulsion, loss of lift, etc.). Among the factors, one can distinguish between the proximate cause of the loss of the airship, and the underlying causes. The organization of this article is something of a compromise among these organizational principles.
The following factors may be identified as having contributed to airship (and for that matter, aircraft) accidents in the past.
- Design Flaws and Limitations
- Political Pressure (to fly)
- Air and Ground Crew Error
Frequently, multiple factors are at play, e.g., a design flaw or limitation creates a crisis when bad weather is encountered, and the crew makes a poor response.
The choice of hydrogen as the lift gas could be considered a “design flaw or limitation,” but the issue of hydrogen safety in the 1632 universe is so big that I will discuss it separately, in part 2.
In the period 1900 to 1970, 162 rigids, about 70 semi-rigids, and about 850 non-rigids were constructed (Khoury 496). In theory we should be able to determine the fate of each of these airships and thereby arrive at statistics on airship safety. Unfortunately, the closest I have come to finding a database of airships that provides the relevant information are reports (Wikipedia/List of Zeppelins; PSAS; Mitchell 67–72) on the fate of the zeppelins of the LZ1 to LZ114 series and of the SL1-22 series (Automotive Industries 1059–60). Even that had omissions, but I was able to compile the following tables.
In table 2A, we have the LZ and SL zeppelins that were destroyed or damaged beyond repair principally as a result of enemy action, which were deliberately destroyed after the war to avoid transfer to another nation, or which did not suffer any accident (they were dismantled, decommissioned, or transferred):
In calculating airship safety in peacetime, we can ignore the ones that were shot down (34) or bombed (5), and we see that 36 had successful service. This may be contrasted to the 59 that were lost for reasons unrelated to enemy action, as listed in table 2B:
The airship (and aircraft pioneer) Alberto Santos-Dumont wrote,
“Naturally I am filled with amazement when I see inventors who have never set foot in the basket drawing up on paper—and even executing in whole or in part—fantastic airships whose balloons are to have capacities of thousands of cubic meters, loaded down with enormous motors which they do not succeed in raising from the ground, and furnished with machinery so complicated that nothing works! Such inventors are afraid of nothing, because they have no idea of the difficulties of the problem.” (Payne 51).
Since the sina qua non of an airship is the ability to leave the ground, airships whose designs are so faulty that they can’t do so are certainly failures. One such was Roze’s Aviator (1901), a double hull (total capacity 47,655 cubic feet) with two vertical propellers and a car suspended between the hulls. (Payne 38). Wellman’s America, in 1910, only rose to 100 feet (Payne 48). Of course, there’s a silver lining to this cloud; an airship that can’t ascend can’t descend either.
The design of airships is fraught with hard choices and vicious circles. To increase speed requires more engine power and thus engine weight. To support the increased weight, the envelope volume must be increased. This in turn increases surface area and thus drag. To increase payload, one needs more lift and thus more envelope volume. The additional fabric adds to the weight and thus one needs still more envelope volume. And of course, making the airship bigger and faster also makes it more expensive. The compromises that are forced upon airship designers sometimes pave the way to disaster.
The general response of designers to inadequate lift was to toss something out. Spiess’ airship (1913) was buoyed by 451,000 cubic feet hydrogen but couldn’t lift both 200 hp engines into air. Spiess first removed one engine. That of course reduced the potential speed. So he lengthened the hull, increasing the gas capacity to 580,000 cubic feet, which permitted him to restore the second engine. (Payne 82).
The British Naval Airship #1 (Mayfly) cost $205,000, carried 663,518 cubic feet gas, and was 512 feet long. Very impressive, except that on its May 22, 1911 attempt, it couldn’t get airborne. (5/22/1911). The authorities removed the external keel and the passenger cabin, lightening it by three tons. (Payne 83). We’ll see what happened next in a later section.
A more common flaw than a complete “failure to launch” is a large airship with uneconomical carrying capacity . Zeppelin’s LZ1 had gross lift of 27,400 pounds but net lift of just 1,500 (Payne 60). Krell’s 33′ foot semirigid (1912) carried 476,739 cf gas but had only 4.5 tons disposable lift (Payne 81).
Inadequate speed—which could be the result of design flaws such as inadequate engines or poor aerodynamics—means that flight times are longer, and also limits the wind conditions that the airship can fly in. Lebaudy’s Tissandier (1914), an airship 426 feet long and with a hull volume of 741,000 cubic feet, had seven 120 hp engines, but nonetheless could only make 37 mph. (Payne 82).
The Schutte-Lanz SL1 (1911), was not only heavy, it experienced too much drag as a result of crossed spiral girders (Payne 82). Theoretically, the spiral configuration should have increased its structural strength. However, the girders were of wood; they absorbed moisture and broke frequently. (Robinson 3).
The design flaws of the R38 became apparent, when, during its third trial (1921), the girders buckled when the dirigible was driven at just two-thirds power (Payne 120). Engineer (later writer) Nevil Shute commented, “It was inexpressibly shocking to me to find that before building the vast and costly structure of R.38 the civil servants concerned had made no attempt to calculate the aerodynamic forces acting on the ship. . . . [My superior] pointed out that no one had been sacked over it, or even suffered any censure. Indeed, he said, the same team of men had been entrusted with the construction of another airship, the R.101. . . .” (Payne 189).
And that lack of analysis proved fatal. The R38 (2,724,000 cubic feet, 695 feet long) was based on the German L48, a “height climber” design. Such zeppelins were lightly built so they could reach an altitude of 22,000 feet, thus avoiding enemy aircraft and AA fire. However, they were not intended to make fancy maneuvers in the dense air of lower altitudes. On Aug. 4, 1921, after the R38 made a series of sharp turns, the hull broke in half. Of the 49 man crew, 44 were killed, but there was no fire.
The R38 designer thought that the static safety factor was 4. Later analysis showed that it was closer to 1 (i.e., no safety factor at all) if the nose were up 10 degrees and the air speed was 54 knots. It also is saddening to note that the R38 could have had twice the girder strength at a weight cost of less than four tons, and this would have reduced its ceiling by only 2,800 feet. (Robinson 48).
No airship better illustrates the ability of presumably intelligent people to make poor design choices than the British R101 (1930). Many of the choices created unnecessary weight. Servomotors were placed on rudders even though, if balanced, they could be steered by hand. It had four engines for forward propulsion and a fifth engine, weighing 3 tons, used just for reversing. It used railroad (Beardmore) diesel engines, which weighed 19 tons, whereas the British R100, designed by the group that Nevil Shute was a part of, employed 9 ton airplane engines. (Payne 195).
The result of these extravagances was that while it had a gross lift of 148 tons, its deadweight was 113 tons. That doesn’t include fuel, and it need over 25 tons to fly to Egypt (its first, politically motivated, destination). Consequently, it was cut in half, and a gasbag inserted to increase lift by 14 tons. (Id.)
The R101 had a heavy steel frame; to reduce weight, it featured fewer longitudinal girders, with a consequent reduction in structural strength. There were further R101 design flaws: the gas valves were too sensitive, opening when the ship rolled; the gasbags chafed against the girders, risking their integrity; and the outer cover rotted where adhesive on the reinforcing tape reacted with the fabric dope. (Payne 201–2).
Some other airships had design flaws worthy of mention. On the pioneering Zeppelin LZ1, the sliding weight (used for pitch control) lever broke, the frame buckled, and the rudder lines fouled. (Payne 60). The Roma, with its original engines, was slow to respond to controls. (Payne 125). The water recovery units on the ZR3 were frozen, or warped by excessive heat. (Robinson 141, 149). The DN-1 (1916) leaked gas, and was both heavy and underpowered. The ZR1, during its shed test, exhibited vibration of the propeller shaft and a leaky valve. (Robinson 69–70).
The aviation pioneer Santos-Dumont operated several personal blimps. These had ballonets, essentially internal air chambers that would empty as the airship ascended and fill as it descended, to compensate for the expansion and contraction of the lift gas during these operations. This served to maintain the aerodynamic shape of the envelope. In the Santos-Dumont #1, in 1898, while descending, the air ballonet didn’t fill fast enough, and the hull folded in half. (In 1899 the Santos-Dumont #2 lost its shape, but in its case, thanks to a rain squall.) (Payne 32–33).
Even if the design is sound, the implementation might not be. A contractor might deliberately and surreptitiously use a cheaper material than that specified by the contract, and pocket the difference. I am not sure why, but the airframe metal on the Zeppelin LZ42 was a poor quality and hence it was only used for training purposes. (Wikipedia/List of Zeppelins).
More commonly, safety measures were deliberately circumvented. On the Severo Pax, in 1902, the gas valves were sealed with wax. Why the operator was worried about venting hydrogen is unclear. (Payne 37).
On the USS Shenandoah, to conserve helium, eight of the sixteen release valves were removed, which limited its ability to vent lift gas to slow an ascent. (Payne 132–6).
Weather has plagued many airship flights. Wellman’s America (1907) suffered compass failure during a two hour snowstorm (Payne 46). On its seventh flight (June 28, 1910), DELAG’s LZ7 (Deutschland) found that with even three engines at full power, it wasn’t able to stay on course in the face of a storm, and was blown into treetops. In 1913, the LZ14 (Navy L1) was caught into a gale, and hurled into the sea—this was the first time that there was loss of life in a zeppelin accident. (Payne 77).
German Army zeppelin IV, in 1914, encountered heavy fog; it tried to navigate by compass. This wasn’t too successful; it landed at a French airship base (leading to accusations of treason when the crew got home). (Payne 76–7). On May 3, 1916, the L20 was blown by a gale to Norway, where it crashed in a fjord. (Payne 99).
In 1917, The British Coastal Class blimp C26 fought headwinds for a long time; this increased fuel consumption and it ran out of fuel. It drifted for a while but managed to land. Then the wind broke the ship loose from its field mooring and it came down unmanned on a house in Eemnes.
On September 3, 1925, the USS Shenandoah was caught in the updraft of a thunderstorm. Beginning at 2100 feet, it rose at a rate of 2 meters/second. Despite being pitched 18 degrees down (for negative aerodynamic lift) and having its valve covers open (so it would automatically vent gas), it rose through its pressure height of 3800 feet, reaching an altitude of 6200 feet. It had vented helium for five minutes and so, with the updraft gone, it dropped at a rate of 1400 feet per minute for two minutes. Attempting to regain buoyancy control, it dumped four tons of water. It rose then dropped again. This time, it had no ballast left. The strain of the descent was such that the control car struts parted. The hull split at frame 130, 200 feet from the bow. However, it did not catch fire. (Payne 132–6).
The Graf Zeppelin struggled with two squalls in October 1928. The first one tore off the bottom cover of the port stabilizer; this took just a day to repair. The second tore the upper covering of the port fin; it took fourteen days to repair. (Dick 38).
The British R100, on its July 29, 1930 flight, encountered severe turbulence, tearing the fabric on three of its four fins. These were repaired in flight. (Reader, please visualize this.) It then encountered a line squall that tossed it 3000 feet up, creating new small tears in the fin.
The USS Akron met its doom on April 3–4, 1933. Its problems began when it encountered fog at 300 to 1500 feet. Static prevented it from receiving some of the weather map information that ground control was trying to transmit to it. It rose above the fog but at 1600 feet encountered violent downdrafts. (Payne 212; Robinson 185–6, 207). As to what happened next, see “crew error.”
While storms and fog are an obvious risk to aircraft, the diurnal and seasonal variations in air temperature affect buoyancy and equipment performance and can require adroit crew responses. The German L59 flew to Africa in 1917. The extreme diurnal temperature changes over a desert region meant that it alternated between superheat (lift gas warmer than ambient air) and supercool (other way around). It tried to avoid venting lift gas or dropping ballast by aerodynamic lift (nose up for positive, nose down for negative), but this wasn’t always successful; the engines tended to overheat or stall when the airship was inclined. (Dick 755ff).
When an emergency is caused by enemy action, adverse weather conditions, or equipment malfunction, the survival of the airship depends on the reactions of the crew. Sometimes, these have left something to be desired. It is not, by the way, always easy to identify crew error as a problem; if the airship is owned by the government or other large institution, the institutional tendency is to blame a crash on circumstances beyond anyone’s control.
We left the USS Akron in a downdraft. The ship fell rapidly, but it released ballast, leveling at 700 feet. It then tried to ascend, putting its elevator up, so it was inclined upward at an angle 20–25 degrees, and revving the engines up to full power. At 800 feet altimeter altitude it felt a shock—its fin had hit the water.
Why? The USS Akron was 785 feet long, and it’s not really the nose that goes up but rather the tail that goes down as a result of the up-elevator. The altimeter altitude was probably inaccurate because of the weather conditions. To compound matters, 73 of the 76 on board died because it carried no life vests and only a single rubber raft. (Payne 212; Robinson 185–6, 207).
Errors in buoyancy control have also proven dangerous, especially when they occurred at low altitude. On the Schwarz #2 (1897), the pilot opened the gas valve by mistake at 800 feet, and the ship crashed. (Payne 29).
On the Severo Pax, in 1902, when the airship rose too fast (which might have been avoided if it had working automatic valves), the aviator dropped ballast instead of venting gas. This accelerated the ascent and the gas bag burst at 2000 feet. (Payne 37).
Also in 1902, Santos-Dumont failed to fully inflate his airship initially. After takeoff, the gas bag folded and burst. (Payne 36).
Engine failure was a definite concern for airship operators. On its March 31, 1936 outbound flight, the Hindenburg carried a spare engine (two tons) in its cargo hold; it left it in Rio. (Dick 111).
The causes of engine failure are many. The Zeppelin LZ-1, on its second flight (Oct. 17, 1900), experienced engine failure because one fuel tank was mistakenly filled with water. (Payne 60). The LZ-2, likewise on its sophomore flight (Jan. 17, 1906), encountered a wind that set up a rolling motion that in turn interrupted fuel flow. (Payne 61). An engine on the LZ-4, during its Aug. 4, 1908 endurance flight, suffered a frozen bearing, and the airship ultimately landed to replace the engine (Payne 64). During the trials of the ZR3 (USS Los Angeles), the crankshaft counterweight broke loose (Robinson 137), and there were also problems with the crankpin bearings (145; cp. Payne 132). On the outbound passage of the Hindenburg‘s first commercial voyage, the wristpin on one of the four engines broke. (Payne 220).
Some engines were more prone to failure than others. The British Submarine Scout (SS) blimps had a single 75 hp Renault engine, which frequently stopped. The mechanic had to climb out on the landing skid to repair it and swing the prop to start it up again. (Payne 111).
Naturally, the harder and longer an engine is working, the more likely it is to fail. In a 1918 incident, four of eleven height climber zeppelins suffered engine problems after fighting gale force winds at 20,000 feet. (Payne 107). In 1925, the ZR1 (USS Shenandoah) had two engines stop when it was inclined nose-down to fight an up-draft. The French Dixmunde (originally, German L72, taken by France after WW I as war reparation), during a 1930 storm, lost three of its six engines. (Payne 123).
If an engine fails, and you need to maintain power (because of a headwind or a schedule to be kept), the other engines need to be revved up, which in turn means that they are more likely to fail.
Loss of all engine power on an airship is not as serious as with an aircraft; an LTA airship will remain at altitude, drifting with the wind. However, loss of engine power renders an airship more vulnerable to other problems, and thus has often been one link on the causative chain leading to loss of a dirigible. Wellman’s America had two 80-hp engines. On its third flight, in 1910, after a few hours one engine was down and the other acting only intermittently. The wind was stronger than the remaining engine (weather problem) and the airship’s equilibrator (a kind of drag rope for buoyancy control) acted like a sea anchor (a design flaw). The America nearly collided with a four-masted schooner. (Payne 48). The LZ24 (German L3) had three engines fail during a 1915 storm, and was driven onto the coast. (Payne 91).
Loss of Lift
Lift can be static (the buoyancy created when air is displaced by a gas that is of lesser density) or dynamic (the lift, positive or negative, created as a result of the flow of air over a vertically symmetric hull if it is inclined relative to the direction of the air flow. If the total lift is less than the weight of the airship, it descends until the two are equal (or until the airship crashes if the deficiency isn’t corrected).
We have already noted that engine failure can result in loss of aerodynamic lift, but here we are concerned with the loss of static (buoyant) lift. The lift generated by the lift gas isn’t constant because its density, and that of the ambient air, vary with temperature and pressure.
A loss of lift has been caused by a cold wind, as in the case of the Blanchard-Jeffries balloon crossing of the English Channel in January 1785. The balloonists only had thirty pounds of ballast, so they improvised, throwing out their lunches, “oars” (they thought they could row through the air), gasbag ornaments, ropes, lines, anchors and even their coats. Still, what saved them was a warm breeze.
The Italia, in 1928, flying dynamically heavy with two of its three engines active, descended below a cloud layer, and cooled in the resulting shade, thus losing lift at less than 800 feet. It had already run out of ballast. It briefly tried to climb with all three engines at full power, but the captain quickly decided that it wasn’t going to succeed and stopped all the engines to reduce the risk of fire when it crashed.
The Zeppelin LZ4 wanted to take off at night but the lift gas had cooled too much. It had to ground a crewman so it could make its ascent.
Lift can also be lost as a result of equipment failure. The Santos-Dumont #5 had a faulty gas valve, which allowed gas to escape. (Payne 34). In 1925, the ZR3 experienced excessive leakage from its gas cells, and the ship was grounded. And of course if there was a serious tear to a gas bag, that was worrisome.
A sudden increase in lift can also be problematic. The ZR3 was hit broadside by a winter gust while it was being walked. The outside temperature dropped 10 degrees, giving it an equivalent superheat. (Robinson 160).
Other Flight Mishaps
On the Laboun airship (1902), the gondola was attached to the gas bag with piano wires guided through eyelets. The nose rose, putting full weight of the airship on the wires, and they unwrapped, releasing the gondola with fatal effect. (Payne 37).
On the Schwarz No. 2, in 1897, the front propeller belt drive slipped. (Payne 29).
On the British Nulli Secundus (1907), the belt drive for the air fan slipped off.
The La Republique (1909) was destroyed because a propeller blade broke off and sliced the envelope. The tear grew rapidly, leading to a catastrophic loss of lift at 500 feet. There were also instances of propellers falling off; this happened twice to the LZ6.
In 1909, the 1400-pound equilibrator drag cable of the Wellman America was snagged by ice, and broke off. This loss of ballast caused the ship to shoot up to 5000 feet, venting so much gas in the process that it was forced to land. (Payne 46).
On the Roma, in 1922, the support cable gave way and the rudder assembly slipped sideways. On the Italia, in 1928, the elevator jammed. It had been flying dynamically heavy (ie., nose down) to compensate for fuel consumed. To avoid crashing, it stopped its engines. Since it was statically light, it rose from 750 to 3300 feet. The elevator wheel was then reassembled. (Payne 154). On June 23, 1921, control wires pulled loose on the R38.
Two US Navy blimps, the G-1 and the G-2, collided in mid-air in 1942.
On the ZR3, in 1926, men were thrown from their bunks during turbulence, and there was an instance of a crewman with pneumonia. (Robinson 141, 149).
Attacked in the Air
The first airship to be shot down by anti-aircraft fire was the L12 (Aug. 9, 1915). It tore two gas cells and came down. It was bombed, but those missed. It was destroyed by a fire during salvage work (Payne 98).
The first airship downed by an enemy plane was the LZ37 (June 7, 1915); strangely enough, the plane flew over the zeppelin and dropped bombs on it. (Payne 96; Correll, Scourge of the Zeppelins (Feb. 2012) in airforcemag.com). Machine gun fire from a plane did down the SL11 on Sept. 3, 1916.
Both incendiary (Pomeroy) and explosive (Brock) shells were used by AA guns and airborne machine guns.
The Zeppelin LZ1 had its gasbag punctured by a signal stake at its landing site in 1900. (Payne 60).
In 1902, Spencer’s 75-foot airship had a near-collision with an express train while landing. It managed to avoid the train, but hit a tree instead, fortunately without suffering any serious damage. (Payne 39).
In 1903, Lebaudy’s Jaune, which was equipped with a 40 hp engine and could achieve a speed of 25 mph, chose to stop its engine, possibly for landing. Whether landing was intentional or not, it was blown into a tree. The envelope burst but there was no fire (and no injuries) (Payne 38).
A pear tree was the nemesis for Zeppelin LZ5 on May 30, 1909. It had the excuse of landing during a heavy rain; the bow was damaged but the ship was flown home. (Payne 69).
For landing, the Graf Zeppelin would face upwind, idle the engines, “weigh off” (to equal buoyancy if the weather was calm, a bit light if it were bumpy), increase speed with nose a bit down, and make a long approach, descending at perhaps 100 feet per minute. Once over the landing field, it would reverse engines, and drop the yaw and side (spider) lines to where they could be grabbed by about 100 members of the ground crew. Once it neared the ground, another 70 ground crew would grab the car rails. (Dick 70).
On April 25, 1935, the Graf Zeppelin, descending at a shallow glide angle, passed through a cloud at 300 feet. It was soaked with seven tons of rainwater, reducing its net lift and steepening its descent. It hurriedly dropped five tons of ballast, but this wasn’t quite enough; it hit the ground 20,000 feet short of the landing site. It lost its left rudder, and the chimney of a native hut, with a fire on the stove, was sticking into its belly. (Dick 56).
The issue of groundhandling has been touched upon so far in the Grantville Gazette only by Kevin Evans, “Wingless Wonders” (Grantville Gazette 19) and then briefly. Since several significant airship accidents have occurred while the vehicle was on the ground, some further explanation seems appropriate.
Accidents can occur to an airship on the ground when it is moored outside (to a mast or some field expedient), being moved into or out of its hangar, during the actual take-off, or after an emergency landing. Strong winds are often but not exclusively a contributing factor.
If an airship is being kept on the ground for a prolonged period of time, its best protection from the weather is to place it in a permanent structure, a hangar. These have taken three basic forms: a stationary building, a building on a turntable, and a floating hangar.
The basic problem with a hangar is getting the airship in and out of it safely, and experience has shown that the airship is easiest to control on the ground if its nose is facing into the wind. With a stationary building, the best one can do is to orient it with prevailing winds in mind, but there is the risk that on any particular day, a crosswind will be blowing when you need to take the airship out of its hangar. At least one hangar, the ZR2 hangar at Bedford, was equipped with a windbreak, but it was found that this made matters worse. (Robinson 38).
The DELAG LZ8 tried to leave its hangar on May 16, 1911, even though the wind was coming from an unfavorable direction, because there were important guests present (i.e., political pressure). It was smashed against the hangar wall, breaking the internal structure in half (surprisingly, the envelope didn’t tear completely). Still, it was a sad event for an airship that had survived more than thirty flights (Payne 71, 73). Political reasons also caused the Hindenburg to be walked out of the hangar in a gusty (18 mph) wind in 1936; the rudder was damaged. (Dick 17).
The USS Akron, coming out of its hangar in 1932, encountered a gust that snapped cables and damaged its tail. (Payne 209). The German L22, in 1916, was caught by the wind and smashed its bow against the hangar door; it was subsequently repaired even though, judging from a photo, at least 70 feet was crumpled. (Payne 99). The LZ12 was caught on its way to the hangar by a storm, and was lifted and dropped, catching fire. (Payne 75).
Perhaps the strangest ground damage incident was one involving the City of Glendale (1929) which, while standing in the sun, popped a seam, because the crewman who was supposed to be monitoring the pressure gauge was having his picture taken. (Payne 138).
At Nordholz, in WW I, the German Navy had a two-airship hangar (“Nobel”) mounted on a railroad turntable; the machinery was hidden beneath the hangar floor. (Belafi 126). Prior to WW I, Count Zeppelin had made use of a hangar floating on a lake; the hangar could be rotated on the water.
The British floating hangar, the Cavendish dock, was fixed, but it was equipped in 1911 with electric winches to ease an airship out even against a beam wind. Unfortunately, on Sept. 24, 1911, when the British Naval Airship #1 (Mayfly) was moved out for full testing, “disaster struck in the form of a sudden forceful beam-side gust causing the ship to lurch, just clearing the shed but laid her on to her beam ends. She righted and was then being pivoted so that her nose would point back out to the dock when there were cracking sounds amidships.” (Airship Heritage Trust). Well, that’s the official view: blame the weather. However, there is a minority report that the problem was a handling error, the aft car fouled a buoy. (Payne 83). The damage was severe; the Mayfly was literally broken in half.
The Zeppelin LZ2, while being towed from its floating hangar, was driven ahead of the tug by a tail wind, causing its nose to be forced down into the water, which broke the steering planes (Payne 61).
The Graf Zeppelin‘s procedure for taking off was to face the ship upwind, held down by the ground crew, drop ballast to make it “light” (say, 900–1200 pounds light, versus the airship’s useful lift of 60,000 pounds and gross lift of 210,000 pounds), and have the ground crew release it upon the command “Up Ship!” The first engine was started up at 150 feet, all engines would be idling by the time it reached 300 feet, and it typically cruised at 575 to 820 feet. (Dick 48, 67). If a downwind takeoff was necessary, it would increase aft buoyancy so the tail came off the ground, the ship would then be lifted dynamically. (Dick 109).
Not all airships were operated as competently as the Graf Zeppelin. Morrell also commissioned a 485 foot airship. During takeoff in 1908, its nose was released late, and it developed excessive pressure of 30 psi, bursting the cloth. Thirteen out of nineteen on board were injured. The builder was not one of the passengers; he had refused to fly, saying that the airship was unsafe. (Payne 44).
Those were the pioneering days of airship flight. But groundhandling accidents happened decades later, too. On Nov. 20, 1923, while the ZR1 (USS Shenandoah) was being walked to its hangar, a downdraft forced its stern down against the ground, damaging it. (Robinson 76).
Less excusably, on May 11, 1932, the ZRS4 (Akron) was attempting to land in the morning while the helium in the gas cells was still cold. However, the local ground crew was inexperienced and slow. This proved fatal for some of them. The tail unexpectedly rose while the ground crew were holding trail ropes. The engine shut down (because the fuel wouldn’t flow) and tons of water were suddenly released from the ballast bags. The mooring cable was cut to prevent a headstand. (Payne 210, Robinson 183). Three didn’t let go of the trail ropes in time, and were carried up; two fell to their deaths and the third was pulled inside the airship.
In flight, an airship might have to make a landing en route, unexpectedly, because of unfavorable weather conditions (storms or strong headwinds), engine failure or structural damage, etc. In the early days, the field expedients weren’t much more complicated than tying the airship to a tree or post. However, I have a picture from a 1920 flight magazine illustrating what was called the three-wire mooring system. There was more than one way of doing this, but several cables were attached to the same shipside anchor point near the nose of the airship, and ran off to three to five separate groundside anchor points, with some cabling running between the latter, too.
Several airships were damaged or destroyed by storms when moored in a field. These included the Zeppelin LZ2 (Jan. 17, 1906) (Payne 62), the LZ4 (Aug. 5, 1908), the LZ5 (April 25, 1910) and even the British R34 (Jan. 27, 1921) (Payne 117). In the case of the LZ4, the wind caught her broadside, snapped her cables, and tossed her into the air, whereupon she burst into flame. All that was left of her was a metal skeleton. (Payne 65). Two companies of soldiers tried to hold down the LZ5, to no avail; she ended up wrapped around a hill. (Payne 72). Another airship lost while on the ground was the American C-5 blimp, on May 15, 1919.
Some of the airship pioneers didn’t have hangars and thus their craft were exposed to field conditions essentially as soon as they were inflated. Morrell’s 300-foot airship, awaiting its maiden voyage in 1908, was torn loose from its moorings and wrecked. (Payne 44).
In between the hangars and the field expedients, we have the mooring masts. They provide a more secure anchor, and greatly reduced groundhandling crew requirements, but provide no protection from the elements. On the other hand, the airship was free to revolve around the mast, and the wind would cause it to “weather vane” around until it faced into the wind. That freedom gave it some protection from wind damage, but conceivably the wind could shift direction so fast as to tear the airship from the mooring before it revolved into a safer orientation, or the wind could be so strong as to overpower the mooring even in the headwind position.
A mooring-only high mast (120 feet tall) with a revolving top was built at Pulham in 1919 for the British R33. There was no provision for transferring crew or supplies between the airship and the ground while it was moored. (Robinson 6).
A “full service” high mast was built at Cardington in 1926. (Robinson). The R101, a rigid airship, had an internal passageway leading to the nose. The nose cap attached by a winch-drawn cable to the mooring eye on top of the mast, and perhaps thirty feet below the nose cap the R101 had a drawbridge structure. This was lowered to engage the circular walkway that was an equal distance below the mooring eye. This full service mast was, obviously, a substantial building, although nowhere near as large as a hangar would have been.
At Dearborn, an experimental high mast had a vertical railway that ran up the mast. In theory, the airship would be attached at the top and the mooring eye would be run down the railway to bring the airship to ground level. (Khoury 319, Robinson 148). Only two airships ever moored at Dearborn, and the railway was never tested, but the idea is nifty enough that I thought I’d mention it.
The first use of a watercraft for launching an aerostat was in 1849, by the Austrian Navy ship Vulcano (which sent a hot air balloon to bomb Venice). Later, during the American Civil War, Lowe launched a hydrogen balloon from the deck of a converted coal barge, the General Washington Parker Custis. But these, and the later WW I tethered balloon carriers, of course didn’t have mooring masts, because a free balloon wouldn’t be coming back to the launch site, and a captive balloon would never leave.
The US Navy had a floating mast, the airship tender Patoka. It took an average of half an hour to moor the USS Shenandoah. When the Navy built larger airships, like the Los Angeles, there was concern that the Patoka or the airship could be damaged if the latter was blown over the Patoka by the wind, and the mast was raised thirty feet. The Los Angeles was maintained on the Patoka mast for 78 hours.
This was not the only floating mast; the Spanish seaplane carrier Dedalo provided one, too.
The first stub (short) was built at Lakehurst in 1927; the Los Angeles moored there, too. (Robinson 155). It was a simple vertical pole mast. That mast was stationary, but a mobile mast can be used to reduce the hazards of walking an airship between the launch site and the hangar.
The first “crawler” mast, built in 1929, was first used to walkout the Los Angeles. (Id.) This was a tripod mast, on a platform equipped with treads. The Macon had a similar mast, but this ran on railroad tracks leading into (or away from) its hangar. The most recent development is the mast truck, in essence a vertical pole mast mounted on a large flatbed truck. One such is used for mooring the modern Zeppelin NT.
There were two basic methods of mooring to a mast, one involving a horizontal approach and the other a vertical one. Horizontal mooring was used by small nonrigid airships and they were walked up to the mast by the ground crew. Vertical mooring was used by large rigid airships and the approach was controlled by winches. (Robinson 75).
Mooring an airship to a mast was no guarantee of safety. On April 16, 1925 the British R33 was ripped from its mast, and then drifted with the anchor watch on board and gas cell #1 deflated. The watch managed to get the engines started, and landed at Cologne. (Payne 118). I believe that the American C5, damaged by a storm on May 15, 1919, had also been on a mast. On Jan. 16, 1924, the Shenandoah broke away from its mast during a 70 mph wind; the anchor crew managed to get it back to the hangar after eight hours. A photo shows the storm damage; fabric ripped off its nose and in a long gash running from the nose along the forebody. (Payne 128).
In 1927, the mast-moored USS Los Angeles was experiencing high superheat (helium hotter than ambient air) at a time when there was a steep temperature gradient in the atmosphere. A wind shift and gust acted aerodynamically to lift the tail. That brought the stern into the colder air resulting in increased lift on the stern, which accelerated the upward movement of the tail.
At the time, there were 24 crewmen on board. The officers tried to send the crew aft to weight down the stern, but of course the upward tilt made that difficult. As the ship’s inclination increased, wires snapped, puncturing the #10 cell, and causing additional damage. The navy tried to suppress the photograph of the airship doing a headstand, and failed, so they gave the incident a positive PR spin by saying, look what the Los Angeles could survive. Repairs only took one day, so it really could have been much worse than it looked. (Robinson 153).
Attacked on the Ground
Instances of airships being attacked while on the ground, save in wartime, have been relatively rare. When Jacques Charles landed his hydrogen balloon at Gonesse in 1783, the gas inside caused the balloon to seem to move of its own accord, and local peasants with pitchforks destroyed it as the work of the devil. (Payne 3). I can readily imagine this happening to an airship in the 1632 universe.
There is also a case of Santos-Dumont’s airship #7 having its gas bag mysteriously slashed, presumably by an unscrupulous competitor. (Payne 35).
The first airship to be bombed was the German LZ25, on Oct. 8, 1914. (Payne 88). It was one of the five zeppelins of the LZ1-114 series that I know to have been bombed.
Loss of the R101: Case Study
We have already discussed at some length the design flaws of the R101, and it is time to comment on its last flight. It was dangerously overloaded, carrying 9 tons of extra fuel and 2–3 tons of ceremonial carpet(!). It had never been given a high speed test or flown in bad weather.
And bad weather was what it encountered; a squall with 50 mph winds. A course correction took it over Beauvais Ridge, where it crashed. The court of inquiry suggested that the proximate cause was a tear in the cover and subsequent failure of the forward gas bag.
However, an alternative explanation is crew error; it was flying heavy and to compensate it was relying on dynamic lift, which depended of course and maintaining both a particular speed and a nose-up inclination. However, it reduced speed at 1000 feet, and dropped its nose.
Loss of USS Macon: Case Study
The USS Macon was brought down by a combination of a design flaw, poor maintenance choices (probably the result of political pressure), bad weather, and crew error.
To save money and weight, the tail fins of the USS Macon were bolted on rather than extending through the hull. The first accident was on Jan. 22, 1932; while leaving the hangar, a gust of wind snapped a cable, causing the tail fin to drag, and bending the girders therein. The second was on April 20, 1934: while crossing the mountains, a broadside wind gust snapped two girders in the tail frame. The Macon continued to fly while repairs were gradually made.
The third and fatal accident came on Feb. 19, 1935. While it made a sharp, high speed (70 mph) turn at 1400 feet, a wind gust struck, causing the Macon to roll violently. The top fin—still not reinforced—parted from the hull. It then lost the rest of the fins, and this resulted in the opening of three gasbags. It lost 30–40,000 pounds of lift aft, so the ship descended with a drooping stern. An emergency dump of all aft ballast was made, making it statically light. It was also dynamically light because of its inclination and the fact that all engines were running. It rose through the pressure height (2800 feet) to 4850 feet over eight minutes, valving helium, and then dropped, hitting the sea 25 minutes later. Two members of the 83 man crew were lost. (Payne 209, 215–6; Robinson 191–2).
Guilt by Association
Several airships that were still airworthy were scrapped because the crash of another airship disillusioned the common sponsor.
The R100 (which cost $2 million in 1930 dollars) scrapped in view of crash of R101 even though it had a different and better engineered design.
The USS Los Angeles (built for the USA by the Germans as the LZ 126, and commissioned in 1924) was first decommissioned in 1932 as an economy measure. After the crash of the USS Akron in 1933, it was returned to service. (Theoretically; its last flight was in 1932). However, the loss of the Macon in 1935 increased skepticism concerning the value of rigid airships and it was placed on the sidelines. It was finally scrapped in 1940.
Personal Injuries in Airship Accidents
Our focus so far has been on how airships get into accidents, but stories are about people, so what happens to them? Injuries can occur from deceleration, flailing and crushing as a result of flying objects and structural deformation. Flailing, at least, can be inhibited by lap and shoulder restraints, but on some airships they weren’t provided, and when they were, they weren’t necessarily used.
Even if there is no immediate injury, crew can be entrapped, and subsequently burnt or drowned. Generally speaking, the crew didn’t have fire-retardant clothing.
A much higher percentage of crewmen survived the crash of the Macon than that of the Akron. Both crashes were at sea, but only the Macon was equipped with life preservers and rafts. Nor was that the only problem; there was no easy way to raise a general alarm, and the internal communication system was poor.
Often, airships had limited escape routes. Also, I don’t think that it was common for them to carry parachutes.
Hopefully, we’ll do better in the new Airship Age.
In part 2, we’ll look at the risk of fire from flammable lift gases and fuel, and the possibility of hydrogen embrittlement of metals and non-metals.