Fuel Air Ratio for Jets

[@unclemonster48]

Damn Jay didn’t know you retired! Wow! We are getting old! Thanks for all the info and videos! It’s been fun learning about what I wished i had went into. I’m just an industrial chiller tech ( scroll, screw, centrifugal ) I pretend I’m wrenching on a turbine sometimes on overhauls. 😂

[@dragancrnogorac3851]

You don't have to read manuals how engine works... Just play all videos from this channel 😂😂😂 I have great time doing it

[@ddegn]

"I have great time doing it" Same here.

[@demiman7]

Agent JayZ, You are hands down, the BEST THING OUT THERE! Because of this channel, your channel, I have actually purchased and started reading the Jeppson Manual on aircraft engines. You bring a special personality to the teaching realm that makes it fascinating to learn about a subject I know very little about. I'm not an engineer, but a Biology and English major. Wow, what you do! Thank you so much, and please keep it going! Michael Demorest, Sacramento, California

[@AgentJayZ]

Thanks for the kind words. Comments like yours make a real difference to me.

[@richwaight]

Love this! Really well explained and so awesome to see the combuster parts too! Thanks for taking the time to post this!

[@grndiesel]

I think people were given a little more credit and also expected to be more competent in the 1950s. Even older automotive shop manuals were far better written and got very deep into the inner workings of the machine (bike, car, truck, tractor, etc.). And of course, liability was a lesser concern. It's a lesson to all of us that old books are more valuable than we may realize, in the digital age.

[@slidey1788]

I saw a quote about how 50s automobile owners manuals showed how to adjust valve clearances. Modern manuals tell you got to drink the contents of the battery. I'm not sure about the accuracy of the above, but the sentiment seems about right.

[@jstogdill]

@@slidey1788 manuals for electronics (stereos, refrigerators, whatever) used to come with circuit schematics.

[@jascott62]

In the 50's the average human intelligence was alot higher than it is now also.

[@jamyers1971]

My '71 Buick Service Manual explains not only how Air Conditioning works, but also how to completely rebuild every part of the system. Same with everything else on the car.

[@Mart-u2u]

In my youth I was exposed to the Pratt&Whitney radial engine version of these tomes. Sweet stuff for an aspiring A&P guy. Ended up going down a different path. Wish I still had that book!

[@volvoguyV70R]

Material technology has evolved over the years. I'm an old JT8D guy, but thanks to military technology, we now have "single crystal" metallurgy available to the commercial world with turbine blades can withstand much higher temperatures and thermal cycles.

[@SkyhawkSteve]

that's a good point about material science being the key to improvement. There were so many ideas that didn't get anywhere until someone figured out how to make a stronger steel, purer silicon, etc.

[@roberthughes6240]

An awkward but somewhat understandable explanation of the thermodynamics of a gas turbine, its very difficult to explain as an overall system because it has so many process stages, you did really well, thank you. Perfect stochiometric combustion is difficult to achieve, there are always compromises within the engine, in a piston ICE, the cooling effect of the cylinder walls and piston, and the levels of turbulence in the cylinder can somewhat retard the flame propergaton process leading to incomplete combustion, a turbine however uses different methods of heat mitigation and can remain closer to a stichiometric combustion, the combustors are also designed to incorporate a consistency of turbulence that mixes the fuel and air in a way that promotes better combustion, therefore if I were asked which of the engine types were the most efficient I would say a gas turbine every time. Thank you for the video AgentJayZ.

[@MrEh5]

Your videos are the best. Watched you for years.

[@balazsegressy3788]

This is the good method to teaching/ explaining. Showing in books and on real components!

[@gregebert5544]

The combustor is an unsung hero; so much attention is focused on the compressor and turbine.

[@Raptorman0909]

While in the USAF I bought an earlier version of the Pratt and Whitney jet engine manual, probably around 1980, give or take. One of the most interesting topics when I first read it was the design and operation of the combustor's and flame holders. The use of a coaxial tube to feed air in for combustion through the center and add air for cooling from the outer section of the coaxial tube was a genius way to permit higher temperature combustion by actively cooling the metal with secondary air from the outer section. I still have the manual but it's not close by so I can't check the publish date or revision number. We've made some progress in materials over the last 8 decades or so permitting higher temps, but it seems most of the improvements are incorporating tricks like using secondary air for cooling that has allowed efficiencies to improve, beyond the increasing bypass ratios by using larger fans. Using secondary air to prevent the combustor and turbines from melting was an early improvement while active cooling the turbine blades from secondary air is a more recent evolution.

[@zapfanzapfan]

A discarded combustion liner could make a sweet lamp shade. Yes, the old illustrations are very clear and also works of art.

[@RodneyHayes-d3y]

My lord man if you used a turbo fan engine with air cooled blades as a reference to answer the air fuel ratio question, I think you head might explode but you did a great job of answering something that is really not an easy answer

[@gregoryfrance1723]

Tungsten is the hottest melting element on the Periodic Table of Elements. 6170° Fahrenheit. Problem is, we cannot melt it to form it as there is nothing we can put it in. So we use it ONLY as a powder metal. Next, it is extremely heavy and brittle. However, it has a very low coefficient of Expansion and Contraction. So if put in tight contact with a metal that has a high coefficient of thermal expansion/Contraction, you may crack the Tungsten part. Fun stuff.

[@tornasever]

What about using powdered metal 3d printers, they have pretty powerful lasers that can probably melt it

[@RGD2k]

No, pure Tungsten is actually really ductile and easy to draw into wires. (eg, good for light bulb filaments, remember those?) You're thinking about Tungsten Carbide, that's brittle. It's still very heavy though, even when pure. Are there any non-brittle carbides?

[@gregoryfrance1723]

@@tornasever we can melt it, but it will melt thru whatever is in contract with it. This is why we don't melt it. Nothing can hold it. as

[@gregoryfrance1723]

@RGD2k Tungsten as a pure element is drawable as you say. But still cannot be melted as whatever it lands on or in will be melted also. So it is mostly used in powder form with other elements added in. Yes, Tungsten Carbide is very hard and brittle, dang near useless. Which is why whenever I welded on it, my filler wire has either Niobium or Titanium to help prevent the formation of complex carbides.

[@gtr1952]

Thanks Jay! After watching, and paying attention to you over the years, I know exactly what your talking about. Thanks much, have a great day! 8) --gary

[@Mart-u2u]

How very interesting. Thanks, young man.

[@kristyskirt9015]

Oh one other sneaky point a turbojet or fanjet that is equipped with afterburner, the total flow still has enough oxygen to mix with the afterburner fuel spay nozzles then lit by the afterburner torch will burn giving extra thrust at a huge amount of fuel consumption. I hope my humble post is close.

[@AgentJayZ]

Close. This is minimum required knowledge for any regular viewer who wants to be a citizen of Jet City.

[@davidwaters6190]

Great, no annoying music.

[@thenerdyouknowabout]

"Interesting in a way that the asker is not currently aware, but is about to become aware" - Youll take this interesting knowledge and YOULL ENJOY IT.

[@atrumluminarium]

The cooling air becoming working air concept that you mention is also something that's becoming mainstream in piston engines nowadays. With higher fuel costs it's a way to squeeze out more efficiency without generating as much NOx emissions.

[@sethlevine8508]

I don't remember subscribing lol. I'm an NDI for the Air Force so I love this content!

[@zapfanzapfan]

I don't hate myself for loving your videos 😉

[@AgentJayZ]

When I watch Low Buck Garage, he always tells me that if I'm not having fun, I'm doing it wrong...

[@AgentJayZ]

Ah! A few days later, Jay gets the Joan Jett reference. Love that girl, and love that song. She's living proof that attitude wins almost every contest.

[@zapfanzapfan]

@@AgentJayZ 👍

[@JSxxxxxxx]

18:45 .. nice moves Great content as always 👍🇦🇺

[@jamyers1971]

I'va had my Jeppson book for years, thanks to JayZed

[@USA__2023]

Can you please enable Closed Captions for your videos. That way us deaf people can learn and enjoy your videos.

[@crono331]

I learned to code in 1980 on ibm manuals from the seventies. I didn't know anything and i understood them. Now with 44 years experience, i cant understand what the modern 'manuals' say.

[@LaTeamPrep]

Very good information, as usual!

[@pedroferreira4134]

Thank you for not having music. Why do people add music is beyond me.

[@HighlanderNorth1]

You mean you'd prefer _NOT_ to be listening to high-volume 80s techno music as you watch technical videos? I'm sure you're the exception....

[@user-rd8hl3ek4n]

@@HighlanderNorth1 That is sarcasm, isn't it? I never understood why some people (not AgentJayZ fortunately), spend days to make a really beautiful video, and then they completely destroy it by adding shitty music on top of it, hiding all the original beautiful engine-, technical-, or nature sounds...

[@HighlanderNorth1]

@@user-rd8hl3ek4n Yeah, I'm just joking. There are many well produced videos with great visual content, which are partially ruined by loud, inappropriate musical "soundtracks".

[@AgentJayZ]

Hey, I usually mute the audio, open another window, and cue up "One World" by Dire Straits, or "Surf Medley" by Junior Brown. KZbin is great; you just need to make it do what you want... by force if necessary. Cheers!

[@zlm001]

Thanks.

[@kawininja6750]

Question unrelated to this video. In a previous video, long ago, you discussed folks finding their own gas turbines for what would be known as 'For Fun'. To stand around it, drink beer, and fire up in the backyard. I would like to know your opinion on what to look for in these types of barn finds, almost like a pre-buy inspection, just to have a better idea of if it will run or not, for the previously mentioned 'Fun'. Love the content, keep it up!

[@AgentJayZ]

Small-ish. Data plate clear photo for ID of exactly what it is. Must turn smoothly with one finger. Must be complete with starter, ignition box, fuel system, fuel nozzles, and all connectors and fasteners. A history, and description of the condition and reason for selling. All of those are deal-breaker essential. Even with all of those, an overhaul, or maintenance, or operation manual will increase your chances of running it from 2% to maybe 50% Otherwise, it's worth the same as a load of gravel.

[@kawininja6750]

@@AgentJayZ Thank you sir, valuable information. The lead that I have is for a 1960s WSK OH-10, a knock off of the famous Rolls Royce Viper (8). But being a Polish copy, and very few in North America, it may very well be just another load of gravel. Fingers crossed that a manual exists. Enjoy your day!

[@jameslyon6129]

I have a disassembly manual for a GG4/J75 it has how every piece comes apart. Lot’s of illustrations and explanations. If you would like I can tell you how I got into fixing jets. Ended up as the technical support manager for the company

[@AgentJayZ]

The J75 is a mighty, huge turbojet. Can you send me a copy?

[@jameslyon6129]

I’ll make a copy and send it to you. Yeah they are a beast.

[@bobqzzi]

Good morning. I hope you are faring well

[@USA-GreedyMenOfNoIntegrity]

I enjoyed 4 years of turbine engine overhaul after 5 yrs military/A&P, but wasn’t working for $12.25/hr dealing with suits the rest of my life. I made the same amount fixing residential heat pumps…27+ yrs. Still, unfortunately nothing has changed for A&P’s.

[@AgentJayZ]

Heyyy.... that's quite the username there, sir.

[@USA-GreedyMenOfNoIntegrity]

@@AgentJayZ I figured you would like that. When you are young, you look up to and trust men in suits, uniforms, those wearing a badge or standing up teaching school or behind the pulpits. Unfortunately, in the USA, there are far too many men that cannot be trusted and get away with their shenanigans, because no one wants to speak out and be the “bad guy”. I spoke out and encourage others too. VAR’s, Video Cameras, Trail Cams, Texting Data, GPS trackers really pizz them off. 😁

[@USA-GreedyMenOfNoIntegrity]

@@Look_What_You_Did I was a certified TIG welder as I went to school at night to learn welding while in the military. I took A&P courses in the military. And I took computer classes in the military. Then I used the G.I. bill to go to HVAC school and made $1.25 more an hour working on heat pumps. I love airplanes and working on them. I’ve spent 2000 hours building my own experimental to fly the family around. Sooner or later, the greedy suits will learn to pay more money to their employees and less to their suits if they want to run a productive company in the USA. Oh yeah, we don’t manufacture anything anymore so all we need are forklift drivers and suits to look important up in the front office of all the warehouses across America.

[@grahamj9101]

Hi AgentJayZ, I'm a little surprised that you didn't open up the Holy Book of Royce, aka The Jet Engine. Chapter 4: Combustion Chambers is very good and the diagram at the top of page 37, showing the percentages of the airflow around and into the combustion chamber would have been ideal for your explanation.

[@slavikrybka]

Ok, 60:1, got it, thanks

[@ddegn]

Yeah but you got to watch the video to see all the beautiful combustor parts.

[@crono331]

Extremely interesting

[@Daniel_Zarate]

🥳🇲🇽 Thanks for your videos!

[@wagsman9999]

It makes sense that the fuel-to-air ratio in a turbojet engine is similar to that of a car. It's the combustion reaction that dictates the ratio... for a fossil fuel that's going to be around 15:1 by weight just because of the chemical reaction involved.

[@AgentJayZ]

Again, this is missing the point of the video. Which is, the air fuel ratio is different whether you include all inlet air, or just the small segregation of airflow diverted to the fuel burning area of the combustors. Which is why there is no "fuel air ratio" for a turbojet engine, but there is one for the combustors.

[@martinperleberg3737]

Great lesson! I have question that I am not sure if you have talked about. Mike Busch of Savvy Aviation talks a lot about how there are not many "real" mechanics nowadays in aviation. although, his work is mainly reciprocating engine maintenance. His point is that there are more "part replacers" than mechanics who can actually diagnose and solve a problem. So, my question is how true is this in turbine engine maintenance? I understand that you are an overhaul mechanic, so a lot of your job IS replacing parts, but I assume you would have a good insight on this topic. Thanks as always.

[@flyonbyya]

My repair manual for my 1979 Datsun 210 is much like Jay describes…Very clear and descriptive. The newer repair manuals are garbage

[@HighlanderNorth1]

(*Disclaimer: My assumption here may be wrong, as it's based on my personal experience). *From what I heard and saw in the 80s, some Datsun/Nissan cars, like the 280z and the mid-late 80s 300zx, tended to have issues, mechanical/electrical, etc. Everyone I can remember who owned one of them had more problems than normal. Example: In 1991, a friend's parents bought him a clean, lower mileage late 80s 300zx. It was to be his primary everyday driver, to supplement the slightly hot rodded 1964 Chevy II that he occasionally drove(450ish hp 350 with auto trans w/ stiff shift kit, etc). But from the get-go, the 300zx had one (expensive)problem after another, resulting in it being in the shop more often than not, and forcing him to drive the 64 Chevy II pretty much all the time. Ironically, the 27 year old garage built weekend warrior hot rod didnt have any issues during that period of time. He ended up selling the 300zx after dealing with its problems for a few months, and he began driving the Chevy II full time. Later on, he spun a bearing in the 350 as a result of driving it hard and shifting it over 7,000 rpms multiple times every day. But that engine had been used in at least 2 other cars prior to being dropped into the Chevy II. So it provided years of fun before being abused to death.

[@fastcars1173]

In drag racing we strive for @1250 Egt's. 11.9 to 12.5 ish AFR using 120+ octane race gas. Ethanol/Methanol AFR's are different, haven't messed with those much but many use it in the turbo world. I'm a Nitrous guy.

[@HimanshuShekhar1]

@@fastcars1173 i fly piston engine RC airplanes that use Nitro fuel (similar to the race car fuels). Nitro fuel provides a bit of its own oxygen as oxygen is part of Nitro fuel's molecular structure. Therefore comparing AFRs between nitro fuel burning engines with regular fuel burning engines is a bit irrelevant. Additionally, professor JayZ's candle and lantern example was spot on for proper understanding of the Air to Fuel Ratios. What a great service this man provides. Thank you is an understatement

[@fastcars1173]

@@HimanshuShekhar1 Please show me where I mentioned Nitromethane/Methanol fuel mix! I mentioned Methanol, Ethanol and Nitrous Oxide as well as race gas (meaning high octane gasoline based racing fuel)! My comment was merely a statement as to what the EGT's and AFR's are in a Nitrous motor using race gas compared to the jet turbines I see in the test cell videos! He videos the parameters on the computer screen during the test! That's it, nothing more. It wasn't a measuring contest in any way what so ever!! Just a statement!! I as well have run a Nitro RC car for 20+ years, I know the difference between Nitro fuel/Methanol/Ethanol/Race Gasoline!! Go project yourself somewhere else please!!!!

[@HimanshuShekhar1]

@@fastcars1173 sounds like I've got my marching orders. Aye Aye Captain. Right away! LOL

[@Mentaculus42]

@@fastcars1173 I have always wanted a good technical explanation of the whole fuel rich to stoichiometric then fuel lean temperature curve for an Otto (gas) engine as it is my understanding that the exhaust gas temperature seems to continue to increase pass the stoichiometric ratio which is somewhat counterintuitive. Remember doing lab experiments with external combustion and the logical maximum temperature is at the stoichiometric ratio. But gas ICEs seem to behave somewhat differently in real life. Is this actually the case? I have always thought it has something to do with the incomplete mixing of the air and fuel where some areas are rich and others are a little leaner and the cylinder can have hot spots. But would like the take from someone who works on racing engines.

[@user-rd8hl3ek4n]

Hoi AgentJayZ, Have you considered selling scrap turbine- and compressor blades to the general public (thus to your viewers), after cleaning them a bit? Or damaged fuel nozzles and combustion cans? Each as separate pieces, for people who would like to put them on display in their living room, as abstract art? "Hey John, what's that thing?" "Well, this is a compressor blade from a Rolls-Royce jet engine from 1955, from a fighter jet. It was damaged in a crash. It's quite unique, there aren't much around." Way more interesting than other art, I think. Would it sell? I don't know, maybe, maybe not. Would you get rich from it? Very unlikely... And yes, you are right about old and new manuals. The old ones were written by tech guys who knew their subject in and out, because they invented it, and who could teach others. The new manuals are written by PR-people that have no clue themself, and that even don't want to tell anything because they think we are dumb idiot customers anyway. The same is true for recent patents, except that they use an incomprehensible word-salad to *hide* the mechanisms of the thing, instead of explaining them. So, I also try to find the older texts on any subject.

[@AgentJayZ]

Funny. Here's the list: Scrap blades: $20 Identified engine type: $50 Cleaned : $100 Polished: $200 Identified according to part number, cleaned, polished, including a history... You get the idea. Shipping not included. These prices do not sit well with "collectors" For reference, new turbine blades for modern engines sell for several thousand dollars apiece.

[@dyhidrogenmonoxide]

I’d pay $20 CAD if you are serious about that :)

[@buttole]

i suppose that reciprocating engines have too much friction to support the same ratio of 'cooling air' as a jet; hence the narrow window of LOP mixture between 'stumbling' and detonation

[@AgentJayZ]

How about we consider the fuel air ratio of a Volkswagen flat four... but we include all the cooling air used by the engine. You might have your 60 to 1 ratio right there.

[@buttole]

@@AgentJayZ ive been told that with aircraft pistons, its traditional to consider at least part of the reason you full rich on takeoff is to let the extra unburned fuel cool the engine. i assume because pistons have inherently so much more friction, that they cant support the amount of extra air among burning fuel that would be required to cool from the inside

[@pauljanssen7594]

I like the one comment it's like a diesel engine fuel the air mixture especially when the turbos kick in a jet engine is one big turbo.

[@AgentJayZ]

And modern airliner engines are turbocharged turbojets...!

[@Pilotman28]

I fly my airplane at peak EGT which is 15:1. We don’t do that at higher than 65% power though.

[@AgentJayZ]

Most of the engines I deal with will have their lowest EGT at 65% rpm. Maybe you meant to type AFR?

[@gueratom]

Am I hearing "I love rock n roll" ?

[@Supernova-hq9hu]

I’ve been a fan for years. You’re finally getting it. I went to film school. Do you need an editor? How about we both get rich. I just want 35%.

[@AgentJayZ]

Real, or a troll from a porno channel? I've just deleted three of those. Seems like it's a new problem...

[@Supernova-hq9hu]

Of the money. You can have all the women you filthy animal.

[@Supernova-hq9hu]

Holy Jesus. It just occurred to me that you actually responded to me. I never say anything if I don’t mean it. I’m a super huge fan. And I’m an editor. Like, I’m an AI editor. Let’s do this shit. We’ll beat Marvel and Lucasville and we’ll put this whole world back together.

[@Supernova-hq9hu]

George Lucas said you have to engineer a film, don’t design it. That’s why it was so special when I was seven years old.

[@fascistpedant758]

On the other hand, Diesel engines don't usually consume that much of the intake air for combustion yet it's all counted in the AFR. Happy retirement! Are you also retiring from YT?

[@louigi6001]

did you get your titanium fan blade as you retired ?

[@AgentJayZ]

No. I have had one on display by my front door for over a decade. I got nothing. Not a handshake, not a thank you, no cupcake, no candle, no picture, no well-wishes. Exactly as I expected. Nothing at all. Yeah the feelings are mutual. Fuckin' A one, Bubba. All those who ignored me, bad mouthed me, lied about me, disrespected me, devalued me, insulted me, interrupted me, ripped me off, and treated me as an afterthought... they can all just do their own thing. They won't miss me, and I will be just fine. I have reached escape velocity, and I am not going back.

[@chrisu3175]

@@AgentJayZ They'll miss you, just in a bigger way than you think.

[@HimanshuShekhar1]

​@@AgentJayZadmire your attitude. A wise guy once said "all the indispensable soldiers are lying in their graves."

[@jwb2814]

@@AgentJayZ WHAT! no cupcake, well f me.

[@Fred2-123]

@@AgentJayZ At my job we had a saying, "I f**king love Motorola and Motorola loves f**king me."

[@chuckkeeler5328]

Why don’t high bypass jet engines have inlet guide veins?

[@lerkzor]

* vanes

[@williamshetler4954]

Because they don't need them.

[@AgentJayZ]

That is a design philosophy question, and those are never really written about. To me, it would seem to make the engine get up to the working range of speeds if the fan would stall at very low rpms, and then it would require less power to turn it until it got to a speed where would start to work. Maybe that's part of it. I would agree that williamshetler4954 is correct.

[@grahamj9101]

There was one big turbofan engine that had fan inlet guide vanes - well, sort of. The TF39 had a half-height first-stage fan, which had full-height outlet guide vanes behind it, in front of a full-height second-stage fan. I believe it was the first big high-bypass turbofan to run, and its fan arrangement was probably unique. Since then, I believe that all big high bypass engines have been as we are now used to seeing them, with the fan turning and nothing in front of it. This must be compelling evidence that IGVs aren't needed for the fan to work - thank goodness! The TF39 fan looks complicated enough, and if a fan can work satisfactorily without IGVs, and without the weight penalty and mechanical complication that would result, then why would any manufacturer do otherwise? Having said this, I'm aware of an engine that didn't have IGVs, but it did have variable pitch fan blades. The M45-SD02 was a demonstrator engine, of which only one was built and tested, back in the 1970s. I'm also aware that R-R Derby considered doing a variable-pitch fan for the Ultrafan engine, but decided that the mechanism would be altogether too complex. And, by the way, the turbojet Olympus 593, which powered Concorde, didn't have IGVs in front of its LP compressor.

[@Mentaculus42]

What is local combustor (within the flame zone only air flow) air to fuel ratio DURING STARTUP when things can get hot?

[@AgentJayZ]

It's just flame temp, same as any time. Start up gets hot because of very low cooling air flow. Have a look at Turbojet Start Sequence.

[@Mentaculus42]

@@AgentJayZ Sorry to ask another question, does some aspects of the air to fuel ratio change when using a gaseous fuel like natural gas that has a nozzle that has a premix region that seems to allow for a leaner mixture with a lower average flame temperature? Don’t some of the turbines that you have worked on use natural gas (vs jet fuel which is liquid and has different flame characteristics, droplets that need to vaporize with basically a flame front at that vaporization surface of the droplet [ l think I read that somewhere]).

[@mikejohnson4617]

I think one reason manuals of today are less informative (and less colorful) than in the past (besides cost) is that manufacturers want customers (and their lawyers) to have only the necessary info and nothing more.

[@failranch9542]

@@mikejohnson4617 it’s because, in my opinion, they farm out the technical writing to someone who doesn’t really understand how it works.

[@nathanflowers7364]

Do you think methanol powered jets are viable

[@AgentJayZ]

Would be very easy to convert a jet fuel system to run with methanol. The exhaust would be less polluting. Reason it's not done is that for the same amount of energy, methanol takes up a greater volume than kerosene.

[@NiHaoMike64]

Is there a way to manufacture methanol in large quantities for cheaper than other fuels? I get the impression ethanol is cheaper to make hence why it's added to gasoline.

[@grahamj9101]

@@NiHaoMike64 Well, every brewery that I know of in England's green and pleasant land (let's forget the dark satanic mills) is manufacturing ethanol, but only at low concentrations. However, there are places that I've visited in Scotland, which specialise in increasing the concentration, only to water it back down again and put it into oak barrels, which are locked away for ten or twelve years. The processes are cheap enough, but His Majesty's Revenue and Customs slaps huge taxes on the stuff - and I've got several bottles of the expensive stuff, having had a big birthday last month. PS It was the Last Night of the Proms only a week ago, so the words of William Blake are fresh in my mind. PPS Get used to seeing the acronym SAF being bandied about in the airline industry. It stands for Sustainable Aviation Fuel. There are start-up businesses busy making the stuff in small quantities from all sorts of garbage.

[@NiHaoMike64]

@@Look_What_You_Did Ethanol is used to boost octane rating.

[@AgentJayZ]

Whatever you call octane rating matters nothing to turbine engines. Nothing.

[@coster3168]

Fuel ratio of a jet I pitcher just like an acetylene torch

[@gregorymalchuk272]

If it's anything like diesel engiens, even at full load the air fuel ratio never gets above 80% of stoichiometric.

[@slavikrybka]

80% of stoichiometric is 11.5 portion of air to 1 portion of fuel, which is too rich to get max performance even with internal combustion engines. The actual number for jet engine, according to mentioned book, is 400% - 60 portions of air (that got inside through the compression wheels) to 1 portion of fuel.

[@gregorymalchuk272]

@@slavikrybka Diesel engines are 80% of stoichiometric on the lean side. They call it the smoke limit.

[@Dave96z34v2]

Hey what happened to the orenda iroquois project?

[@AgentJayZ]

The owner of the engine appears to have lost interest. I really hope he remembers how important that thing is to Canadian aviation history.

[@dohabandit]

Easy, just make your turbine sections out of diamonds or THC (no pot heads, not the stuff you buy in vape shops....tantalum hafnium carbide.)

[@fascistpedant758]

Diamond burns. You'd need a pretty rich AFR to minimize any free oxygen in the combustion gasses.

[@anthonyrowland9072]

So lean is mean in a turbine too...

[@Transit_Biker]

I bought the workbook my mistake vs the textbook. Oops.

[@nuttyDesignAndFab]

lean burn baby, super efficient!

[@kizzjd9578]

How can we send you a flag to hang up?

[@AgentJayZ]

Address on channel page. Not too big, ok?

[@osamarabee3927]

[@dohabandit]

Problem is you have to take into account for bypass air (in high bypass engines), bleed air, and air that is used for cooling that never enters the combustion chamber.

[@Mentaculus42]

‽

[@Apexseals87]

here's the thing, we have materials that can handle those higher temperatures. but they weigh a lot more, those nickel based alloys are just too heavy for high performance jet engines. otoh, gas turbines and steam turbines....those dont care that much about it as they sit at a given rpm for hours, days, weeks, months on end. since they use titanium, they're limited to those lower temps, as titanium goes soft very quickly at relatively low temperatures.

[@AgentJayZ]

You sir, are sadly misinformed. Since before the J47, back in the 1940s, gas turbine nozzles and blades have been made of high nickel alloys. No combustion gas turbine has ever been made of titanium alloys. Now Git.

[@melclark1066]

Thanks for your explanation, very easy to understand, But: I believe the questioner really wanted to compare the fuel to air ratio of combustion, as is usually talked about with an ICE engine. That should be easy to calculate as it would be the weight of Air needed to combust , say one pound of jet fuel : yes there would be some variation, as like an ICE engine not all of the fuel is necessarily completely burned, but a ball park figure should be achievable, You could (if required) then calculate a secondary ratio of that weight of air, to the total weight of air passing through the engine. Does this make sense, or am I talking rubbish?😎

[@AgentJayZ]

Well, that may be what you thought, but that was not the question. It turned out to be an opportinunity the show how these machines are definitely not piston engines.

[@jfan4reva]

Practically speaking, everything I know about gas turbine engines I learned from AgentJayZ/Zed/Zulu. That includes what works and what doesn't (Looking at you - Internet Tomatoe juice can jet engines!) Thanks AgentJayZZZ!