# Tag Info

37

Yes, and it has been demonstrated 30 years ago on the Tupolev 155. This is/was a hydrogen-powered version of the Russian Tu-154B tri-jet. Only one has been built and has since been retired after demonstrating the use of liquid hydrogen in 5 experimental flights. In total, the Tu-155 performed about 100 flights with several fuels, among them hydrogen and ...

26

Yes, indeed the plan to build a hydrogen-powered jet laid the groundwork for using hydrogen in the Centaur rockets and the upper stages of the Saturn 5. While hydrogen was used only experimentally in test rigs, the Soviet Union built a derivative of a regular airliner, the Tupolev 155, for testing hydrogen and natural gas in flight. EDIT: NACA also did in-...

23

First, to debunk a myth regarding the Hindenberg, which always gets brought up whenever hydrogen is mentioned. Hydrogen is less safe than liquid fuel, but it is not less safe than natural gas or propane. Hydrogen has a higher flame propagation velocity than hydrocarbon gasses, but contains much less energy per unit volume than hydrocarbon gasses. A huge ...

22

In gaseous form, the amount of -- the mass of -- hydrogen you could store in the volume of aircraft fuel tanks would be negligible. In order to store enough mass of hydrogen, you'd have to store it liquified, which is how it's stored in rockets. In order for that to be useful, though, you'd have to have engines entirely redesigned in order to burn cryogenic ...

18

For fuels intended for use in aircraft, the key performance parameter is the energy density of the fuel: how much potential work is stored in how many liters of stuff. High energy density means the fuel tanks will be small and the energy released upon burning a liter of it will be large. The problem with using hydrogen as aircraft fuel is that its energy ...

18

Aviation is very energy-hungry. While hydrogen is quite efficient in terms of energy per mass (141.8 MJ/kg), it is awful in terms of energy per volume. Aircraft today use their wings for fuel storage, which helps to reduce bending loads and uses a volume unsuitable to transport payload. This will not work for hydrogen. The biggest problem is storage, and ...

14

Using water as the carrier and splitting it on-board to hydrogen and oxygen is a nonstarter. Electrolysis takes vast amounts of electric power, so instead of just water you need to carry water plus (big, heavy) batteries. If you use batteries, you're better off just using electric motors to drive the turbines, that would be lighter than an electrolysis setup....

14

Hydrogen works just fine on rockets. However "just fine" on rockets doesn't mean it is practical on an aircraft. The only way you can utilize $\mathrm{H}_2$ is storing it cryogenically. This is because $\mathrm{H}_2$ goes supercritical at $-240\,{}^\circ\mathrm{C}$, and no matter how hard you squeeze it beyond this temperature it would refuse to liquify and ...

14

Let's do some quick math. Air has a density of about 1.3 g/L and hydrogen has a density of about 0.09 g/L. The best case for lifting force would be storing the hydrogen at the same pressure as the surrounding air. This means that every L of hydrogen can displace 1.21 g of air, reducing the density of the aircraft. The amount of air displaced by the aircraft (...

8

Von Ohain's first prototype of his HeS 3 turbojet, the HeS 1, burned hydrogen in the first runs. Only after some modifications was he able to make it work with a liquid fuel. https://en.wikipedia.org/wiki/Heinkel_HeS_1

8

Consider the nature of liquid hydrogen. In a liquid, non boiling state, it must be at a temperature of 22 Kelvin, which is -253C/-423F. Extremely cold. This calls for heavily insulated containers, and an accidental release could be extremely dangerous. A few gallons of liquid hydrogen spilled on you would turn you into an ice cube almost instantly. It is ...

8

Buoyancy (a.k.a. static lift) depends on the volume of the object. If you put something else in the tanks, the buoyancy does not change. What can change, however, is the weight. If you wanted to use it as fuel, you'd have to take such amount as to get the same combustion heat as you get from kerosene. Hydrogen has lower¹ heating value 119.96 MJ/kg and ...

7

Hydrogen works just fine as turbine fuel, and does so in space launch turbopumps. Achieving full efficiency, power, and engine life on hydrogen will require tweaks to a pre-existing engine, of course. On the environmental side, H2 normally burns hotter than hydrocarbons, which produces more N2O, but combustion temperatures can be regulated, and have to be ...

6

This is not fully on topic ('Aviation'), but answers the question in some way: Hydrogen is currently considered the 'fuel of the future' for existing and new gas turbines in power plants, for small and large gas turbines equally. The industry is working to enable all existing turbine lines to handle that, and the modifications are minor (well, minor ...

6

No. If you want to use hydrogen as fuel, you need a lot of it, which means you need to pressurize it. Hydrogen is less dense than air when it's at ordinary atmospheric pressure but, as you start to pressurize it (i.e., fit a greater mass of hydrogen into a fixed volume), that advantage decreases. Worse, if your fuel is pressurized, you need to store it in a ...

6

Your plan is to not store the hydrogen, but generate the hydrogen inflight. The problem is that generating hydrogen inflight is even more awkward than storing it. The component chemicals you combine to make hydrogen are much, much heavier than the hydrogen itself (hardly a surprise since hydrogen is by far the lightest atom)... and both heavier and more ...

4

A hydrogen fuel tank, by nature, must be cylindrical. To save weight it must be short and stout, not long and narrow. On an aircraft, it must also be at the center of gravity, so it does not throw the aircraft out of balance as fuel is spent. This also necessitates a short tank, not a long length-of-fuselage tank (all the hydrogen would roll fore or aft ...

4

Airbus will store hydrogen by chemically binding it to carbon for a looong time. This way, it can be put into the wings, a belly tank and the horizontal tail and its gradual disappearance during the flight will not shift the center of gravity much. What the PR department just published is just for political correctness. It has not been thoroughly checked for ...

3

The situation is not as dire as one might think, as the energy content per kilogram of hydrogen is 3.3 times larger than that of kerosene (142 vs 43 MJ/kg): Wikipedia: Energy Density - Energy density in energy storage and in fuel Taking into account a slight weight saving in wings, and a little heavier hydrogen tank and fuel lines (insulation, pressure),...

3

Hydrogen has to be in gaseous state to burn. The boiling point of hydrogen is ~20 kelvins, while oxygen boils at about 90 kelvins and freezes to solid at ~54 kelvins. It is therefore impossible to mix these two for combustion if hydrogen is in liquid state. A non scientific answer to pumping liquid hydrogen directly to the combustion chamber is, that it will ...

3

By using a generator which converts water into hydrogen gas, we can just use water as our main fuel source which is more cost efficient? NO! Splitting water into hydrogen and oxygen, done at 100% efficiency, takes exactly as much energy as you get back from burning that hydrogen in the oxygen, at 100% efficiency. Where are you getting all that energy from ...

3

It may turn out that compressed hydrogen will be excellent for fixed structures where storage volume is not as great an issue. Transportation such as trucks or aircraft greater favor higher energy density, or liquid fuels. Exotic applications in rocketry favor the higher specific impulse per gram of hydrogen compared with hydrocarbon (more bonds to oxidize ...

3

Airbus have claimed they aim to produce hydrogen-fuelled passenger planes that could be in service by 2035. They have developed three ZEROe concept designs. Unveiling its latest blueprints, Airbus said its turbofan design could carry up to 200 passengers more than 2,000 miles, while a turboprop concept would have a 50% lower capacity and range. A third, &...

2

It would increase lift if it were unpressurized. Of course, it would also increase volume by a few orders of magnitude if it were going to produce enough lift to matter in the context of a significantly-sized aircraft, which would lead to form drag penalties that far outweighed the lift benefit for craft that fly anything close to the speeds used in modern ...

2

Based on my reading, the biggest disadvantage of hydrogen as an engine fuel is its low density. Even when stored as a cryogenic liquid, it take up more than ten times the space as the same mass of kerosene, which means the same size tanks will hold only about a third as much energy (even though hydrogen has about three times the energy content per kilogram ...

2

NACA (the predecessor to NASA), has burned hydrogen in a turbojet engine in flight. There is an extensive history of NACA's and NASA's experimentation with hydrogen as a fuel on the NASA history website. In the 1950s NACA burned hydrogen in a turbojet engine on a modified B-57 aircraft as part of Project Bee: A technical report on the in-flight ...

1

I guess the first Aircraft flying with a Turbine, the Heinkel-178, with the Turbine of Hans Joachim Pabst von Ohain, patent US2256198, inventor stated M Hahn, had the jet engine tested with Hydrogen as fuel, the issue with Hydrogen may be storage. www.SAE.org has documents about Hydrogen as Automotive Fuel, no need being member to purchase.

1

Google "cryoplane final report" or just cryoplane for a full answer. Jet liners using cryogenic hydrogen are feasible but won't be cheap unless hydrogen becomes very cheap. It might do that as renewable energy sources like wind and solar could generate hydrogen by electrolysis when their electricity output is greater than demand the time.

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