Why not Gaseous Fuels for Aircraft ? 

Yes. Even an engine I am very familiar with: the J79. I don't write scripts, and a camera deactivates 80% of your brain. Try it and see! Thanks, bud.

The Rolls Royce Spey also did this.

I have noticed that your use of terminology is very precise (and obviously the proper industry specific technical term) such as your use of “reheat” vs afterburner which makes sense. I noticed that you used the term “fuel spray nozzles” vs injectors in the context of a hydrogen fueled turbine. When reading the literature the term “injector” is sometimes used. Is there a proper use of the term injector in regard to a turbine or is this function always a “nozzle” (maybe higher fuel pressure for a liquid fuel to promote atomization vs a gaseous fuel nozzle)? From what I can gather, hydrogen is an outlier as a fuel with regard to combustor design due to its high reactivity, high flame front speed, potential for high flame front temperature (potential for high NOx production due to potentially high localized temperature). It seems that the combustor / nozzle design (& configuration) needs to be optimized for hydrogen to get a good balance with its performance? It seems that the significant work that is on going to fuel electrical power production turbines with hydrogen or ammonia (characteristic mostly the opposite to hydrogen) are moving rather cautiously as optimizing combustor design is very challenging (Diffusion Combustion System vs Dry Low Emissions (DLE) Lean Premixed Combustion System vs Sequential Combustor vs Micromixer Combustor). With that in mind, a high level question relevant to this video with regard to the use of “gaseous fuels” is why is Airbus putting a lot of emphasis on hydrogen (vs Boeing who seems to assume that some type of E-Fuel can be swapped in, providing the production can be scaled while bio-fuels are unlikely to scale that large)? When I run through the “gaseous fuel scenario” implications on the overall aircraft design, it requires a complete rethinking of layout and approach. Would find your thoughts on this subject enlightening.

DLE's? That being the case I think you'll well know that beyond the basics that the changes to the FSNs, dilution and traverse are going to be kept under wraps 😉

Good thing, then, that there is no molecular hydrogen in the combustion gases. It has all been burned, and turned into water vapor. Hydrogen is the best fuel. Methane, being CH4 is the next best. Natural gas is mostly methane. Gas turbines that run on natural gas have the least problems with hot section corrosion.

I do agree. The people who say that airliners do not use fuel are probably incapable of understanding this fine point.

i dont get how would that work

Venturi effect . Spray a small volume of fluid ( liquid, gas or vapour) through the venturi and it will try to increase in volume to fill the space so it will drag the surrounding fluid with it. This technology is used for millions of applications, spray guns, carburettors, jet pumps including deep well pumps, steam whistles, boiler feed injectors, musical instruments, gas stoves etc etc.

Google “ejector pump”. They are used extensively in aircraft. No moving parts, therefore quite reliable.

@@mikenewman4078 I understand venturi, but usually you need a pump or a movement of a fluid to get the cycle started. Wouldn't you still need that to at least get the airplane off the ground?

@AdmissionGaming the internal tanks have electric pumps in them to move the fuel around, drop tanks, and ferry tanks have venturi. The pumps induce the flow to get things moving. Also as long as there is no restriction a gas turbine will pull fuel with its own pumps upto about 80% without a LP system backing pressure

News flash... If it would work, it would be done.

There is a thermostat for the oil. On the engine featured here, it is very similar in construction to the one for coolant in cars. your other question is interesting. I can only guess that the decision of which tanks to fill is the job of the captain. I have talked to a few, and they fill the centerwing fuel tank first. Next time I'm at Oshkosh, I will ask them to explain it more.

Several reasons come to mind. Noise reduction is one. The fan is extremely noisy, so if it is recessed in an inlet that has noise reduction tech applied to it, then a lot of fan noise that would reflect of the walls of the inlet is absorbed. The metal walls of the inlet are riddled with thousands of tiny holes, and these help break up reflected sound waves. Also, a close look at many fan inlets will show that they have a slightly increasing internal diameter from front to back. The divergent pathway acts as a diffuser in subsonic flight, converting some of the velocity of the incoming air into pressure. The helps improve engine function in its designed-for condition, which for an airliner engine is flying along at cruising speed. Both of these effects work better with an inlet duct which is a couple of feet in length rather than a couple of inches.

As I have answered before, I'm just passing on what I was told by a guy who drives a 777.

You're probably thinking about a match going into a pool of diesel, not gasoline. Gasoline flashpoint= -43c Diesel flashpoint= +62c

The most promising aviation biofuels are liquids. Biggest challenge is meeting the strict quality standards for commercial use and still be cost competitive.

@NiHaoMike64 Cost is indeed the biggest problem at the moment based on the economies of scale. We have flown across the Atlantic using SAF on the Virgin flight and that used a specific SAF blend however the range dependent on the supplier is around 4 to 8x the cost of a litre of AVTUR. There is no difference in engine performance using the fuel buy obviously it would force ticket prices up. In terms of general engine testing at the moment a SAF/AVTUR blend is used to test both production and development Trent engines. However its very chicken and egg, carriers want a supply and suppliers want a demand and until the supply is there then carriers will hedge their bets. Also worth noting that some SAF products do not carry the aromatics which cause seals to swell and seal fully so unless you carry out a whole fuel system seal mod programme there will need to be blends and additives

The reason the tanks are so heavy, is that they never rupture.

I think something along the lines of a biodiesel that is somehow treated to stay liquid at -60F.

You saw that? "cause the engines were obviously performing to the satisfaction of the pilot, who chose to do the takeoff run, which absolute max power... and then the engines quit. We have run J79 turbojets on JetA1, Diesel, and even home heating fuel... all with no issues right to max AB. That sounds like really dirty fuel, eventually blocking up the filters, being bypassed straight to the fuel control, which quit. Did you see the crash?

@@AgentJayZ I was told about the incident when I was working at a Logistic's AFB in the 90's , it happened on another base , the engines used in the Talon are small , maybe they couldn't keep ignition as well ?

J85's are good reliable engines. Flaming out on rotation means they were at takeoff power, and had been running fine like that for at least 20 seconds. If it was the properties of the fuel being the problem, the pilot would never have initiated the takeoff. They ran fine, and then quit, which indicates fuel contamination, as described above. Both engines quitting at exactly the same time corroborates, and also rules out any problems with the actual engines. I would say the event happened due to contaminated fuel, not the type of fuel. Also, I think it's just a story, because aircraft fuel trucks are very distinctive, especially at an Air Force base. One would never be filled with diesel, for any reason. Those fuelers take their jobs very seriously, so I doubt this incident ever even happened.

@@AgentJayZ Your probably correct Jay , the aircraft did crash for sure , and it was stuck in my memory as the fuel because of local communication , ironically I believe your side now after decades of what I was told ! That's why I look forward to your videos , I know they're solid and correct !

I've just posted this in response to another question. The Pegasus engines in the Sea Harriers, as used in the Falklands conflict, were cleared for the emergency use of Class A diesel fuel. This was, of course, the fuel being burnt in the four Marine Olympus engines (derived from the 200 series aero engines in the Avro Vulcan) that powered the Invincible-class carriers. Even if the diesel fuel in that tanker was the same as that dispensed at a roadside gas station, I certainly can't imagine it causing a flame-out and a double engine failure so soon after rotation. The worst that I could imagine is that, when the error has been discovered after the flight had been completed, there might have been some build-up of 'soot' on the burners. The engines would then have been removed and their condition (and that of their fuel systems) investigated in detail. As AgentJayZ has observed, the engines must have been operating normally enough for the pilots to attempt the take-off. Like him, I suspect fuel contamination (shades of the crash of a BAC One-Eleven on a German autobahn back in 1971).

It shortens the service life of the fuel pumps and controls, but engine performance is the same.

Retired in 1990, the RAF’s Avro Shackleton (“forty thousand rivets flying in close formation”) was a maritime patrol aircraft, powered by four Rolls-Royce Griffon engines - except a few were six-engined, with two Amstrong Siddeley Viper jet engines in the outboard nacelles behind the Griffons. They were there primarily for a boost on take-off (there was a joke that a heavily-loaded Shackleton could only take off because of the curvature of the earth). There was no way that a separate supply of kerosene would be made available for the Vipers (risk of fuel mix up?), so they used the high-octane stuff that fuelled the Griffons. With the relatively low usage of the Vipers, there was no problem with either engine or fuel system component life. However, traces of lead were found in the front bearing housings of the engines, where it could have only been carried by the lube oil. But how? I don’t think they ever found out.

The Pegasus engines in the Sea Harriers, as used in the Falklands conflict, were cleared for the emergency use of Class A diesel fuel. This was, of course, the fuel being burnt in the four Marine Olympus engines (derived from the 200 series aero engines in the Avro Vulcan) that powered the Invincible-class carriers.

A number of alternate fuels have been considered for emergency use in gas turbine engines. They may run hotter or be more prone to hot starts and because those fuels may not lubricate pumps and other stuff, engine life may shorten. Remember, this is for emergency use for these fuels so you're using them to save your life because the usual fuels aren't available... and this is at the expense of the engine. I'd throw away the engine if it meant I'm escaping grave danger to live another day.

The question was about gaseous fuels. Let's not get too distracted.

Not on any RR engine I have seen in service. Generally the biggest use of fuel is for the operation of VIGV and VSV systems through fueldrolic pressure or for cooling oil through the FCOC. Do you mean GTS/APU

As with all "what if" questions, with enough money, anything is possible.

The fuel in a B-52 wing is part of the structure itself , flexing is minimized by the compressing of the liquid , when the wet wings are drained it's time to exit load and go home .

Christin: This is pure garbage. If the tanks worked the way you claim, it would only be when they were filled right to overflowing, with zero airspace. Once the aircraft consumed even a few gallons of fuel, the hydraulic supporting effect you describe would disappear. So you are spewing garbage. If you can refer me to a flight manual, or an operators manual, I retract my claim that you are full of shit. Otherwise... you are full of shit.

Well, thanks for your info. I'll pass your correction on to the 777 captain next time I see him. I hope you are right... calling either him or me (or both) incompetent in basic memory. Just sayin... If you have never been in the left seat for a transatlantic flight on a triple 7, and you have not carried out the weight and balance calculations for it... are you ready to correct someone who did it many times? Not me; I take his word for it. Oh, right. I can't be trusted to remember the simplest things...

For what it's worth I'm a chemist and I didn't see anything wrong with how you described things. Thanks for another interesting video (even if I knew this stuff already). Aren't most of the fuel hoax nuts also flat earthers? They are insufferable.

G'day, Not as such. "Wing Tank" Equals an actual Fuel Tank, or Bladder, inside the Wing Structure... "Wet-Wing" Tanks are using the Wing Skins & Spars and Ribs, suitably sealed with Chemicals sprayed on from the inside..., as the Top, Bottom & Sides Of An integral Fueltank.... Depending on the Sealant, The ending of the Story varies. The Sealant in the General Dynamics F-111 Fuel Tanks was sufficiently potent that every 10 years someone wearing a Mask with Goggles breathing compressed Air fed in through a Hose, had to crawl inside the Wings, wearing nothing but Underpants due to the tight constricted space, and use a Solvent to scrape out the old Sealant..., "Dealing" they called it - and their Underpants always totally Dissolved during their shift. Then someone had to go back in and Reseal the things. Apparently everyone who did the Desealing, and about half those who did the Resealing..., All died, early, of Rare Cancers... So, in honour of the Type's Unique History...; One or two were saved for Museums, And the rest were Literally Bulldozed into Landfill... The Taxpayers have deep pockets, Apparently. And Endless Volunteers seeking Employment. Such is life, Have a good one... Stay safe. ;-p Ciao !

Either one would be just fine. I don't know about a mixture, but I would bet it would also work well. The combustion section can use anything that burns. The fuel control needs a consistent, low viscosity liquid. It's better if that liquid has a small amount of lubrication properties. This is why diesel or kerosene is preferable to gasoline. In terms of power output... the engine is controlled via temperature. If more of a less energetic fuel is needed to reach a desired temperature... more of it will be used. Here is my answer to a very similar question a couple of weeks ago: With adjustments to the fuel control, it'll work well on ethanol, methanol, kerosene, gasoline, diesel, lamp oil, home heating fuel, any aviation fuel. Different fuel system required, but the core will also run on hydrogen, natural gas methane, propane, anhydrous ammonia, or even acetylene. Hmm, that last one might be a bit of a worry

@@AgentJayZ wow thank you so much for the answer !! It really helped me 😁

It was tried decades ago in the early days of industrial gas turbine engines. The resultant ash did nasty things to the turbine aerofoils. Check out what happened to the engines of British Airways flight BA009 on 24 June 1982. And then there was the grounding of flights over Europe in 2010, as a result of the volcanic ash cloud from an eruption in Iceland. The effect of burning pulverised coal in the combustion chamber of an industrial engine would be very similar. However, coal could certainly be used to produce gas (well, that was the old-fashioned way of producing the domestic gas supply), which could be burned in the combustion chamber.

@@grahamj9101 The engines that flew though an ash cloud, yes I have seen images of turbine blades from that. Maybe if the coal was pure enough? But making that might be more expensive than it is worth. Yes, the old city-gas, the gas-clock (gas tower?) here in town was just dismantled, it had not been used for decades but there were owls nesting there I think and so tearing it down became complicated. Some enthusiasts still use wood-gas to power their car like we did during WWII, I guess that counts as bio fuel 🙂

@zapfanzapfan All the coal that I've ever burnt (and I still have a fireplace) produced copious amounts of ash. The obvious way to purify it is to produce coal gas. Even small amounts of ash, or even soft particulate carbon, will slowly erode the turbine aerofoils. I recall that we had an installation that was burning ethane, which resulted in the build-up of 'horns' of carbon on the burners. The turbine blades were noticeably eroded in a matter of hundreds of hours by the carbon being shed. We cured the problem by introducing a feed of air through the centre of the burner head.

@@grahamj9101 I was thinking something like coke but even that still has some impurities. But if even pure carbon erodes the blades then it seems a fools errand to try coke dust.

@@zapfanzapfan AgentJayZ suggests that atomised liquid fuel is vaporised almost instantly and is effectively gaseous when it burns, but I’m not so sure. However, I should be meeting up with some fellow R-R retirees tomorrow, one of whom was a combustion engineer. I’ll ask him a few questions. In respect of pulverised coke, the particles will most certainly not vaporise, and will take a finite time to burn. I can imagine tiny sparks of burning coke going into the turbine and doing a very effective job of eroding the blades.

There are these things called regulators. You should look into that. Hydrogen production involves using electricity. It has been shown that massive amounts of electricity can be generated without using hydrocarbon fuels. Bing Bang.

Unfortunately I don’t think physics lets you do that. But ammonia or liquid methane could work.

There has been work on technologies to do this, but it's not a trivial thing to design and implement. Search for "chemical sponge to store gaseous hydrogen" to learn more.

@@davidg3944ah interesting. As long as the “sponge” doesn’t weigh too much, maybe

@@alanh2820 The tech doesn't allow for "lightweight" storage yet, but I never rule anything out when it comes to research (with sufficient money, that is).

We could try something crazy like bonding the hydrogen to carbon. Have long chains that are just chock full of energy. Energy that's easily used when you burn those long chains of hydrogen and carbon. Naw it's just too crazy to work. Due to the laws of physics it would always take more energy to create those chemicals than you could get burning them. But if the planet just happened to do it for us long ago. Well all that cheap, easily used energy would be downright revolutionary.

You sir, are a gentleman and a scholar. I much prefer hearing from a knowledgeable fellow such as yourself, and not the alternative. I am always taken aback by how much irrelevant crap is attracted by the subject of fuel for engines.

That's what I said. Did you watch the vid?

Conspiracy lovers will hold on to their beliefs no matter what you do. They have to help themselves out of it or nobody will.

I don’t count myself among them, but it is true that the term was coined by the CIA to debunk truths that were being told. Maybe we should just call them theories, unless there’s clear evidence to debunk them?

700bar not 70😜

That is true, but the weight of the hydrogen storage tank is compensated for by the car not having to haul around an internal combustion engine. That engine, even if the largest parts (the engine block and cylinder heads) were made from aluminium alloy, would still be heavier than the power unit the Mirai actually uses - a combination of an electric motor and the fuel cell stack which takes the hydrogen from the tank, combines it with oxygen from the air to make the electricity the electric motor uses. So even though the hydrogen storage tank is heavier than an equivalent liquid fuel tank filled with either gasoline or diesel, the overall power generating system (combination of fuel tank, fuel cells and electric motor) is still lighter weight than the power generating system an internal combustion engine car would otherwise need - the fuel tank, engine and gearbox - and you can include the gearbox in that because electric cars don't need one. The equivalent comparison for an aircraft doesn't work because the engine is still the same turbofan or turboprop, the only aspect being changed is the fuel storage system, which for hydrogen would involve a lot of dead weight the aircraft would have to carry around even if the tank is empty. This especially doesn't work because while in a car or truck the weight of the fuel tank and diesel or gasoline inside it is only a few percent of the whole vehicle, for aircraft the fuel is a much more significant proportion of the total weight: For a typical airliner the fuel can be as much as 25% of the takeoff weight if the tanks are full, and for some fighter jets the fuel can be even more than that - I seem to remember that for an F14 Tomcat or an F15 strike eagle, the fuel can be more than 50% of the takeoff weight if the tanks are full - and they usually will be full because the engines on those fighters burn fuel at a stupendous rate, which gets downright ludicrous when they switch the afterburners on. Ok, so in theory you could replace the engines on an airliner with electric motors, but in practice that's not a great idea because electric motors of a power output comparable to even a small airliner engine would probably be heavier than the turbofan or turboprop, and that's before you even think about the size of the batteries or fuel cells you would need to provide electricity to run them. Basically, what works reasonably well for a car or truck doesn't necessarily scale up all that well for something the size and power requirement of an airliner.

@@lloydevans2900 "...is still lighter weight than the power generating system an internal combustion engine car would otherwise need" Pure nonsense. Even when a fuel cell is used to power a propeller using an electric motor, the hydrogen fuel cell and its fuel are far, FAR heavier than an equivalent ICE and its fuel, this is why hydrogen fuel cell aircraft have such a short range, while also being so under-powered. The Mirai is also extremely heavy and under-powered. "...and you can include the gearbox in that because electric cars don't need one." The vast majority still have one... or more.

@@PistonAvatarGuyIf you're talking about aircraft, I completely agree - because even light aircraft (excluding ultralights like powered paragliders) usually need engines capable of generating far more power than most car engines can make. Also because the size and weight of electric motors doesn't really scale linearly with power output. For example, electric motors rated at several thousand horsepower can be made and do exist, because they are used on ships with turbo-electric transmission systems. Which is ok for a big ship where size and weight are less of an issue than for aircraft. But you would probably struggle to fit an electric motor of that kind of power class to a plane - and be able to actually fly it afterwards. When it comes to the Mirai - are you referring to the original one or the new model? Because the powertrain components in the latter are about half the weight of the original, as well as being more powerful: The original had 150 HP, the new one has 170 HP. Which admittedly isn't a lot by 1950s Muscle Car standards, but is well within the average power range for cars made today. The fuel cells are PEM type which are much lighter weight, the lithium-ion backup battery is much lighter than the Ni-MH pack in the older model, even the hydrogen tanks are lightweight COPVs, with the same hydrogen content (per tank - the new model has 3 tanks), which certainly do not weigh 70 Kg each.

Oh, good... you are convinced, because you've proven it. As a professional aircraft gas turbine engine overhaul technician, I am stating that you do not understand the subject, and your "research" is simply seeing what you want to see. What you can picture with your imagination is not evidence, and is not information useful to anyone. You will really not enjoy my video called Hoaxtard Discussion. I recommend you stay away from it, because it is about you. Self-evaluation is the road to hubris !

​@@AgentJayZ I have the greatest respect for guys like you sir. I'm sure I've commented my concerns on one of your past videos. I'd love to see all of your videos because I just love these technical subjects . You're right , I did saw exactly what I was looking for.. Namely the insides of wing cavities large enough for a man to climb through, yet not one stain of moisture or even a mere drop of fuel remained . No pumps visible , no tubes, wires absolutely nothing to support the claims. I can write a book about all the things I haven't seen in the wings of a plane.

The burden of proof is on you guys. Name calling , insults , and never addressing the details of our doubts actually strengthens our resolve . I laughed my head off when a plane crashed on the runway prior to take off, the wing was ripped open and nearly off near the root. NOT A DROP of fuel anywhere.

Actually, if the general understanding of the world is unacceptable to you, then it is up to you to explain to everybody just how the world does work. All the hoaxtards keep claiming there is a jet fuel hoax, but not one of you has taken even the first step to explaining how these great and powerful engines run without fuel. The burden of proof of your ideas is on you, sir. The world is not interested in anecdotal stories about how you can not believe or accept what is going on. The world is waiting for the first tiny particle of actual evidence for why and how jet engines do not use fuel. We will wait forever, because you've got nothing.

​@@AgentJayZWell sir I did watch your Hoaxtard video, no doubt most conspiracy buffs are parrots who lack the technical background and understanding of how to solve the real world problems in either of our fields. The jet fuel hoax got its wings ( pun intended) from the ridiculous amount of weight a fully fueled comercial plane is claimed to carry. A good analogy is a car with a fuel tank that weights 50 % or higher than the total weight of the car. The impact this would have on fuel efficiency and and overall performance would be devastating. To apply simular conditions to a flying craft would be exponentially worse. Let's use the lightest materials possible then load it down with over 100 tons of fuel. I really don't care what people believe, but that makes no sense at all. Red flag alert. These modern powerful compressors upon reaching a certain rpm are damn near free energy devices. When air is compressed beyond a certain threshold some claim that nitrogen( a secret component of the air we breath) becomes a fuel under such conditions. Every liquid known to man becomes afterburner fuel under such conditions. But these roads I avoid. Ive tried to find evidence of the fuel especially in the wings. And so far not one drop can be found. The plane engineers said it's there, I say it's not. The burden of proof is upon the claimant and designer not those who've raised valid doubts. The masses believe what they're told, I believe what I've actually seen. Show me the fuel.

Those where marty mcfly words for his father to talk to loraine

Liquid hydrogen has bout 2.9 times more energy than kerosene by mass.

Most people don't get physics, at least, not beyond a very basic grade-school level. Quite a shame when you think about how much it would benefit the citizens of a country to be more educated. We might be able to keep the cheats and lunatics out of office...

Calling me an "anti jet fuel conspiracy nut" is inaccurate. 1 I am not a nut. 2 "they" call it the jet fuel hoax conspiracy 3 "they" are morons, who are afraid to find out the truth that they claim they are seeking, or already fantasize that they know. 4 saying I am against "them" gives legitimacy to their ignorance. 5 "they" do not exist 6 it's best not to feed the morons and their ignorant fantasies of knowledge 7 all they do is complain, yet they have not one dust speck... not one molecule of supporting evidence to their claims. 8 the evidence against their claims is reality... the way the world works. 9 if anyone is gonna claim that the world does not work the way we all generally understand it does.... they better have some compelling evidence to back up their claims... 10 all I hear from the hoaxtards is crickets...

@@AgentJayZ I think the OP is posting to say that you’re against the conspiracy nuts, not that you are a nut hahah.

Correction: you got lost. The way you turn your difficulty into my failure... you'll make a great manager.

you should rewatch it. he explains good and I clear up things I have learned from rocket science and not quite get it.

No, a fine spray of liquid is still a liquid. Mostly, the question is about storage, not after injecting the fuel.