Hydrogen and Helium in Rigid Airship Operations

The two primary lifting gases used by airships have been hydrogen and helium.

Hydrogen is the earth’s lightest element, and it can be obtained easily and inexpensively, but its flammability makes it unacceptable for manned airship operations.

In addition to the famous Hindenburg disaster, dozens of hydrogen airships were destroyed by fire, and no American airship has been inflated with hydrogen since the crash of the U.S. Army airship Roma in 1922.  The use of hydrogen as a lifting gas for passenger airships was completely abandoned by the late 1930s.

Hindenburg disaster at Lakehurst

Hydrogen fire destroys Hindenburg, May 6, 1937

 

Burning wreckage of the U.S. Army's hydrogen airship Roma; Norfolk, Virginia - February 21, 1922.

Burning wreckage of U.S. Army hydrogen airship Roma. Norfolk, VA, February 21, 1922.

Helium’s non-flammable nature makes it the only practical lifting gas for manned lighter-than-air flight, but it is scarce and expensive, and the use of helium can reduce a rigid airship’s payload by more than half.

While the use of helium presented obvious operational challenges, airships of sufficient size were able to operate effectively when inflated with helium. LZ-129 Hindenburg was designed to operate with helium and could have conducted transatlantic operations to North America, although with a much smaller payload, with helium as a lifting gas, and the U.S. Navy’s rigid airships were also able to fulfill their missions inflated with helium; U.S.S. Akron and U.S.S. Macon served as airborne aircraft carriers, carrying embarked fixed-wing aircraft, using the heavier gas.

Hydrogen and Helium: The Basics

Hydrogen and Helium are the two lightest elements on the periodic table:

Hydrogen
Atomic symbol: H (as a gas, H2)
Atomic number: 1
Atomic weight: 1.007
Helium
Atomic symbol: He
Atomic number: 2
Atomic weight: 4.002

The atomic weight of a helium atom (4.002) is approximately four times that of an individual hydrogen atom (1.007), but since gaseous hydrogen is a diatomic molecule containing two hydrogen atoms (H2), helium gas is only twice as heavy as hydrogen gas.

The Relative Lifting Ability of Hydrogen and Helium

Although helium weighs twice as much hydrogen, because each gas is so much lighter than air helium provides about 93% of hydrogen’s lift at full purity. In practical operation it is impossible to achieve or maintain 100% purity of either gas, reducing helium’s lifting ability to about 88% of the lift of hydrogen.

The actual lifting ability of each gas varies with temperature, pressure, and humidity, and to take account of varying atmospheric conditions and gas impurities airship designers often conservatively estimated helium’s lift at 60 lbs per 1,000 cubic feet and hydrogen’s lift at 68 lbs per 1,000 cubic feet.

Relative lifting ability of 100% Hydrogen vs. Helium
60° F, Barometric Pressure 29.92″ Hg

Weight of Lifting Gas
(per 1,000 cu. ft.)
Weight of Air
(per 1,000 cu. ft.)
Net Lift
(per 1,000 cu. ft.)
Hydrogen5.31 lbs76.36 lbs71.05 lbs
Helium10.54 lbs76.36 lbs65.82 lbs

 

The Effect of Helium on Airship Range and Payload

In actual use, because of physical realities and operational considerations, the use of helium can reduce an airship’s payload lift by almost half.

Fixed Weight vs. Lifting Gas

Much of an airship’s weight is fixed (the dead weight of the ship’s structure and engines, and required weight such as crew and ballast) so the entire effect of the reduced lift of helium is absorbed by the ship’s payload; a helium-inflated airship therefore has a much lower payload for passengers and freight, and a much shorter range (because it can carry less fuel), than a hydrogen-inflated airship of the same size.

Operational Factors

Operational factors further decrease the payload of a helium-inflated airship.

Lower initial inflation:

As an airship rises its lifting gas expands, so an airship that begins a flight with its gas cells fully inflated must release gas as it climbs to keep the cells from bursting. Because hydrogen is inexpensive and easy to manufacture, hydrogen airships usually began flights fully inflated to maximize payload and released hydrogen as they climbed. But since helium has always been a rare and expensive gas, helium airships began their flights only 90-95% inflated — thus reducing payload — to allow the gas cells to expand without the need to release valuable helium.

Exhaust recovery apparatus:

Hydrogen and helium airships also had different means of compensating for the lost weight of fuel burned in flight. Hydrogen ships simply released inexpensive and easy-to-replace hydrogen, but helium-inflated ships required equipment to recover water from engine exhaust to compensate for the weight of burned fuel and avoid releasing valuable helium; the weight of this heavy equipment further reduced the payload available for fuel, passengers, and freight.

Payload Effect of Helium versus Hydrogen

LZ-126/ZR-3:

LZ-126/U.S.S. Los Angeles gives a real world example of the difference between operating the same ship with helium versus hydrogen.

When the German-built LZ-126 flew from Germany to the United States for delivery to the U.S. Navy in 1924 it was inflated with hydrogen, and the ship made the flight from Friedrichshafen, Germany to Lakehurst, New Jersey — 5,006 miles — nonstop. When the United States Navy operated the same ship with helium, as U.S.S. Los Angeles, its range was limited to 3,925 statute miles and it could not have made the same transatlantic flight. And never again did the ship fly as long as it did on its delivery flight with hydrogen, which lasted 81 hours, 32 minutes; ZR-3’s longest flight with helium was a little over 48 hours.

LZ-126 / ZR-3 Los AngelesLZ-126 (hydrogen)ZR-3 (helium)
Gross lift179,266 lbs153,000 lbs
Empty weight77,836 lbs90,400 lbs
Useful lift101,430 lbs63,100 lbs

 

LZ-129 Hindenburg

The following chart illustrates the dramatic reduction in payload between helium and hydrogen by comparing the actual payload from a Hindenburg flight across the South Atlantic using hydrogen with the same flight if the ship had used helium.

LZ-129 Hindenburgkglbs
Dead weight118,000260,145
Crew5,40011,905
Provisions3,0006,614
Fuel58,880129,808
Oil4,0008,818
Ballast7,95017,527
Misc.9,12020,106
206,350454,924
Gross lift/hydrogen (68lbs/1,000 cu. ft.)215,910476,000
Payload for passengers, mail, freight w/ hydrogen9,56021,076
Gross lift/helium  (60lbs/1,000 cu. ft.)190,509420,000
Payload for passengers, mail, freight w/ helium-15,841-34,924

 

Inflated with hydrogen, Hindenburg was able to carry 21,076 lbs of payload; if the ship had been inflated with helium it could not have made the flight at all.

(Information is based on Hindenburg Flight No. 10, from Rio de Janeiro to Friedrichshafen on April 6, 1936, as reported by U.S. Navy Lt. Cdr. Scott E. Peck.)

 

 

187
Leave a Reply

avatar
70 Comment threads
117 Thread replies
72 Followers
 
Most reacted comment
Hottest comment thread
117 Comment authors
Chris MynattJohn HansenFLYPOOLDuke PorterChuck Recent comment authors
  Subscribe  
newest oldest most voted
Notify of
John Hansen
John Hansen

If they could only find some helium 3. It’s atomic weight is only 3 since it only has one neutron. Now that would be the ideal lifting gas!

FLYPOOL
FLYPOOL

Excuse me, what is the purity of helium in a helium airship? , what is the price of helium with this purity?

Duke Porter
Duke Porter

No sustainable future for commercial LTA transportation can exist without the use of hydrogen as the primary lifting gas. Further, the use of hydrogen for propulsion and other power/energy requirements by airships will significantly enhance the positive environmental impact such vehicles will exhibit. This, in turn, will greatly improve public… Read more »

Chuck
Chuck

Doesn’t the comparitive % of lift provided change significantly with altitude and pressure? One way or the other.

Robert
Robert

Actually I think your numbers are off. With a volume of 7063000 the Hindenburg would have lift of 511500lb. After it’s weight 215000 it would have a lot of lift left. And if it was helium it would still have lift. It would have 423000 pound of lift. That’s still… Read more »

Chris Mynatt
Chris Mynatt

You are correct but they want to hide the fact. I am not even sure about the Hindenburg story because I honestly think if it did happen then it was staged. I believe that we were flying comfortably in those ships all over the Earth and we used the jet… Read more »

Henry
Henry

I wonder how vacuum (for theoretical vacuum airship) compares to hydrogen and helium?

J.T.
J.T.

If hydrogen was used, would it be possible to use a fuel cell for ballast? Create hydrogen through electrolysis for lift, fuel cell creates electricity for weight? For a fully sustainable energy future, hydrogen will likely be a part of that future. Transportation is a major issue for hydrogen. Has… Read more »

Guillermo Cornejo
Guillermo Cornejo

I’ve been contemplating this concept too, for years. With modern tech, the Hindenburg design would have 10x more payload I think. But it still wouldn’t beat transatlantic ships as those are extremely fuel efficient; it would win on speed, number of trips per year and could find a niche with… Read more »

Chris Mynatt
Chris Mynatt

I believe you are mistaken because with airships you could use the jet stream going both ways to get around the Earth.

amine
amine

why so many crew ? why oil and hydraulic system when you can use fly by wire ? why too much fuel when we have nore powerful and efficient piston engines ? why don’t use carbon fiber instead of alumminium ? and what is Misc by the way ? Damn… Read more »

Dondonesque
Dondonesque

Very interesting! What would be the practicality of either mixing a small amount of hydrogen with helium (I gather less than 3.9 mol% of hydrogen in helium is classified as not inflammable)? Or perhaps isolating an interior envelope of hydrogen in an exterior envelope of helium? An internet search seems… Read more »

JOHN GREENER
JOHN GREENER

WOW, great minds think alike!! I was wondering that too. Considering Helium’s scarcity and hydrogen’s lifting power (and my fascination with airship travel) I had wondered about a design of the same thing – a hydrogen interior surrounded by say a graphene based skin (or something similar since I believe… Read more »

Dondonesque
Dondonesque

Hi John Greener, Not sure why I neglected your reply so long! Clearly there’s some enthusiasm for the idea, and Antony has demonstrated there’s a precedent. Surely a hydrogen envelope tapped only for buoyancy reasons, and otherwise isolated from the air by a static reservoir of helium, would be no… Read more »

Antony
Antony

The Germans investigated this idea for use in the Hindenburg, with a small hydrogen cell suspended within helium gas bags, the idea being that as the ship rose, the inexpensive hydrogen would be released. Tests were undertaken and the final design and location of the gas valves on the ship… Read more »

Dondonesque
Dondonesque

Thank you kindly, Antony, I should have an opportunity to read up on that this Summer. Alas, it sounds like one more historical missed opportunity.

Antony
Antony

There is a reference to this system on page 93 of The Golden Age of the Great Passenger Airships Graf Zeppelin and Hindenburg by Harold Dick and Douglas Robinson (1985) and page 37 of Zeppelin Hindenburg by Dan Grossman, Cheryl Ganz and Patrick Russell (2019).

Burt Buchen
Burt Buchen

Today scientists are developing hydrogen powered cars. Their great challenge is said to be the small amount of hydrogen produced for the cost of extracting it with complex and expensive machinery. If early in the 20th century we were able to produce the extreme amounts of the gas for dirigibles… Read more »

Guillermo Cornejo
Guillermo Cornejo

Hydrogen is cheap to produce. The problem with cars is that they need a network of gas stations, and thats not cheap