Working on a Turbojet:14 - Fuel System

[@santiagomichelena7763]

Another good video here !! I want to let you know that I have a friend that studies a master of Aeronautic Engines in Cranfield University, England, and his teacher in the middle of the class while trying to explain something, shows one of your videos, and recommend all the student to watch them!! You are really an important teacher for all of us!! Keep doing this stuff!! Thank you very much!!

[@AgentJayZ]

Cool. I hope all the students have entered the draw to win a giant titanium fan blade.

[@chuckeberth4370]

I like your videos as I've always been curious of the mystical magical way a gas turbine works. I was on three different U.S. Coast Guard cutters which were powered by two P&W FT-4 turbines which burned in excess of 6000 gallons per hour. For normal cruising we also had two Fairbanks-Morse twelve cylinder, twenty four opposed piston engines producing thirty five hundred hp.

[@Thomasgm490]

Very informative.. thank you.. as an a&p student your videos are extremely helpful to further understand turbine engine systems & their components. It's a shame the FAA still allows videos from the 1960's instead of hiring an experienced fella like you to create updated versions..

[@lyntonr6188]

Great video agentJayZ. Just to put it in prospective, one minute of fuel under full military power in that engine would run my motorbike for about 1700km, it really is impressive just how much fuel those engines use and how much power they produce. Thanks for all your work making these videos and taking the time explain in great detail such mechanical marvels to a simple Australian machinist like me.

[@TeemarkConvair]

thanks jay. kinda get accustomed to watching your videos, and have to remember to thank you for taking your time to give us our "fix".

[@AIM54A]

Thank you for bringing back the square!

[@bobl78]

it is a miracle to me how a fuel control works just on mechanics, pressures etc...no electronics.... I think about the effort of developing this thing ... I mean how long were they tring until this worked.. lets make hole no 344 a little smaller and valve 78 a little bigger and see if that works.. crazy

[@drewkeepemrunning3839]

The mind boggles ! lol The outside is more complex than the inside ....

[@rafihussain]

Fantastic. greatly enlighten

[@mikecowen6507]

Sir Jay, at 13:45, what is the duct at center top frame that looks like a giant vacuum cleaner nozzle? If I've learned properly, it appears to come from the mid frame and extend over the combustor case. Thank you, teacher!

[@AgentJayZ]

You mean at 12:45... that is a duct for air to come out of the combustor outer case, to be used for anti-icing. The valve is electrically operated by the pilot, and it sits just forward of the midframe. It normally leads to a manifold, distributing hot compressor discharge air to the struts in the front frame. In this video the manifold is not there. All of this is outside our square for this episode...

[@mikecowen6507]

AgentJayZ Yes. My typo. Thanks for playing along! Consider it a birthday present. Yes, it's outside the square, but with all the small variants on these engines, you never know when, or if you'll ever see a certain thing again (like that cartridge starter). Have to strike when opportunity presents itself! I'd love to have the TMs for a J79 to cover my "whazzat" questions,, but cannot justify the cost for simple curiosity on a fixed income.

[@Schtuperfly]

"There are many drains to drain away all the fuel that gets past any seals and drain it all away in the most environmentally unfriendly way possible" LOL it all makes sense to me now why that pretzel I waited in line a half hour for at the air show tasted like kerosene after I got buzzed by a Blue Angel.

[@deSloleye]

As far as I recall all j79 type engines are stripped down from tail to front with the engine resting on the front frame (and things fitted to support the rotor when the thrust bearing is removed). Is it ever done the other way, with the engine resting on the ground with the front in the air? I think you've shown us engines with one half of the compressor casing removed but I can't remember if that was a cutaway display engine or an engine in for repair.

[@AgentJayZ]

The J79 is designed to be disassembled from the rear. It would not be possible to do anything but remove external accessories and maybe the front frame while sitting on its ass. Also, disassembly in the horizontal position would be very difficult.

[@Joeandfran]

Fascinating! Thanks so much for the enlightenment. I am so curious about the difference in fuel use and method of operation between very early engines and the latest "high economy" airliner engines. No, I'm not in the market for one...just technically curious!

[@jasonphillips8552]

My question is how are the engines rotated from vertical to horizontal? A lift or hoist i’m sure but where are the mounting points for the chains or straps?

[@shabaznihal8427]

J brother how fuel control works how does it calculat exact amount of fuel to inject into combuster

[@Ratzfourtyfour]

It's governed by a whole bunch of parameters, like rpm, temperatures, pressure differences, throttle setting and so on, you can picture it as a multidimensional map that the the fuel flow is determined by.

[@acatisfinetoo3018]

So i am guessing all that complicated mechanical fuel system is replaced by an ECU in modern engines?

[@AgentJayZ]

It's called a FADEC, and it monitors even more sensors... only one of them being the power requested.

[@HeadinTheClouts]

After an overhaul, and before the first startup, are there procedures to charge all the fuel lines, pumps and coolers?Does air need to be evacuated or bled off, or does the pump blow all that thru during run up?

[@AgentJayZ]

We pressurize the system with the boost pump, and let things get happy. The inlet of the main fuel pump is normally supplied with about 25 psi fuel from the boost pump, which is typically at the fuel tank.

[@mikecowen6507]

AgentJayZ In terms of "getting happy", I'm still not clear on where or how the air actually gets out of the system. Ok, you have 25psi fuel applied to previously dry lines. I'm picturing 25psi trapped air with nowhere to go until the throttle opens (which I presume would only take a few seconds to purge). I'd appreciate a clarification. Thanks!

[@AgentJayZ]

There are bleed ports, and remember the fuel nozzles are like showerhead. They are not "fuel injectors" and do not have integral valves.

[@mikecowen6507]

AgentJayZ Gotcha! So if I understand, the fuel lines downstream (toward the nozzles) are normally dry (having bled out the piddle pipe out back?) and fill that final section of the fuel system at every start. I suppose that also gives a bit of a soft start in addition to only having 2 ignitors to light the full ring.

[@leodikinis7390]

I would like to know more about multi shaft engines. Could you please give your opinion on the PW gear turbofan.

[@AgentJayZ]

Have a look at my video called Turbojet or Turbofan. Also one called Twin Shaft Turbine Engine Bearings.

[@dreddwailing6395]

That lot looks very vulnerable to a bullet or splinter of shrapnel for a fighter plane, are there any armoured panels fitted to it?

[@AgentJayZ]

No, that's not how aircraft are built.

[@todddembsky8321]

So the do-hicky, does that feed the thing-a-jiggy before being sent to the Doodad prior to being ejected into the ground crews face by the what-ja-ma-call-it? Dumb Question -- to convert to propane, I am assuming new fuel nozzles, new fuel lines, fuel pumps, new fuel control module and no afterburner.

[@AgentJayZ]

Yes. The entire fuel system for natural gas or propane is off-engine, except for the fuel nozzles, and quite a bit simpler than the aircraft liquid fuel equipment. And no afterburner.

[@cck1496]

Excellent video. I have some stupid questions. I will be very thankful to you if you could reply in your spare time. These are: 1) How much this fuel system is different from FADEC? 2) is there any specific reason for these blue color fittings on hydraulic or fuel lines? 3) Power plants are always crying about controlling nox. What about modern airliners? Do they don't bother about pollution control, Diffusion flame and premix flame? Thanking you for sparing your valuable time.

[@AgentJayZ]

1) The J79 uses a hydromechanical system that does not need electricity to function, and is completely analog. 2) The fittings are made of anodized aluminum. The color is incidental. Black or natural aluminum are also common colors. 3) Airliner engines are continuously being improved in terms of power, fuel efficiency, noise and emissions levels.

[@guyh3403]

Now... One hour later after watching this video, my jaw is still on my desk... 90 gallons per minute. omg

[@flatearthdork3825]

Hendrik Hendrikson hmm, in one video he says 200 gallons per minute... in another one it was 2 gallons... these assertions vary wildly

[@AgentJayZ]

Not correct. Of course for different engines the fuel consumption will be different. For the J79, it's as described in this video.

[@gradertfamilymakes]

Can you explain jetcity and this place you are at now? SNS Turbines... Do you work at two different places?

[@AgentJayZ]

Jet City Turbines, S&S Turbines, The Test Cell, SSME, Maddex Turbines... these are all locations in a quantum microverse. AgentJayZ is the name of a particle, related to the Heatilon, for which a precise location can never be determined; only the probability of occupying any of these locations at any moment in time. That probability is always non-zero. Make sense?

[@gradertfamilymakes]

AgentJayZ Not quite. But one would assume the location would be somewhere in the region of Fort St. John.

[@mikecowen6507]

theboxmodder I'd say you're correct. It appears there's so much work to go around, these friendly Canadians benefit greatly from sharing resources amongst their group.

[@hommie789]

Jay I know I say this everytime I watch your video and I am sorry it is repetitive as I am to pedestrian to come up with something different but great video Jay, the amount of info you have in a video is unreal and so interesting. Question, I asked when the fuel pressure in the fuel system was but how about the after burner? Does it run about the same pressure as the main engine fuel system or would it be lower, higher? Thanks again Jay for all the work you put into this for our enjoyment.

[@AgentJayZ]

The main fuel system has delivery pressure between about 100 and 900 psi. The AB fuel system delivers up to 400 psi.

[@SheepInACart]

So dumb question, but if running on gas is desirable at times, why not mix oil into the fuel when doing so? Even under afterburners, a standard 2 stroke 50:1 mix would be only like 1.8 gallons a minute, or 108 gallons an hour. Sacrificing one fiftieth of the max power or fuel range sounds a lot less expensive than shorter lives before overhaul...

[@AgentJayZ]

Gasoline is never preferred, but considered an alternate fuel in a pinch. Making a special additive would be seen as an endorsement of its use. Also you would need to have some on hand. Or 2 stroke oil... in 55 gallon drum quantities. And then you need to mix it with gasoline, in several hundred gallon batches... If you can plan and organize for that, you can probably plan ahead and have JetA on hand, eh?

[@FabricatorFactory]

😎 Great job.

[@complexgrafix]

Thanks

[@ms24444]

Kinda sad to hear its not going back into an F4 Phantom ....

[@AgentJayZ]

At this time, Phantoms only fly as target drones, to be shot down by pilots practicing their aim. This engine will likely be in operation for a few decades at least. Just a little FYI...

[@ms24444]

So sad. What is the typical fuel line pressures we are dealing with?

[@jimsvideos7201]

You mean to tell me an F-4 has engines built differently for left and right?

[@AgentJayZ]

Not really. There are a few differences in the mounting, a couple linkages, and a few lines. Otherwise the left and right engines are identical.

[@MrAntonioxi]

how about run diesel? start injiction is broblem..

[@Ratzfourtyfour]

I've seen a guy on KZbin doing an ignition test on jet fuel and diesel. Diesel is actually easier to ignite than jet fuel (which is a plus in regard of safety when you think about it).

[@bmbpdk]

@@Ratzfourtyfour Could it be this video watch?v=7nL10C7FSbE

[@fredcarter2894]

Snow? What are you talking about this "snow J !

[@bccev770]

By the looks of things this engine looks mmm hahaaaa 50 no 100 times harder than a 350 Chevy to work on. Give or take

[@AgentJayZ]

Honestly, it's maybe 1.5 times harder to work on than a Chev 350... but there are 20 times more things to do, so it takes a long time...

[@bccev770]

Nah man its way way wayyyyyyyyyyyy more technical, maybe easy for you. Thx for reply its an honour to have had this chat with you. Ben from Adelaide Australia.

[@Colaholiker]

Regarding those tin foil hat guys stealing your videos... if that jet engine "runs on air" because the starter is powered by air, I can claim that my Honda Fit is running on a small 12V/35Ah battery, because that's what powers the starter. Whoa, I'm driving an electric vehicle, and I don't even have to hook up a charger! /sarcasm Joking aside, that crap that they stole your videos for makes me want to pay those guys a visit. But not to have a beer, you know? Seriously, how can people even believe in the crap these idiots tell? Especially with people like you on KZbin, explaining these jet engines down to the last bolt? I can really understand that you're pissed about that crap and I hope this doesn't stop you from comtinuing your great work!

[@AgentJayZ]

It makes me feel great every time those "people" don't fool one of us... the jet people!

[@Colaholiker]

I'm not a jet person, like you - I never worked on a jet engine. But as an engineer, i understand how a jet engne works. Surely I wouldn't be able to design one or even do all the maths, but I understand the principle. So I refuse to even think about some sinister superpower that tries to make us believe it works the way it actually works to hide some weird idea of how it could not even work... (wtf?) But some people are just plain stupid. I live close to one of Europe's biggest airport, and those who constantly fight against the airport always say planes dump fuel on any regular approach. They don't want to see that most planes can't even do that, since they are missing a dump valve, and they also refuse to understand that doing this on a regular basis (other than in an emergency where it is a standard procedure for some aircraft) is simply a waste of money. I have given up to debate with these people and just let them be stupid. It's their decision. ;-)

[@profblindserv]

I hate that guy that babbling about engines running on air. I got irritated he used your videos... he is just weird. Mmmmm jet fuel

[@xioux24]

Ignorance is soooo frustrating... aplanetruth. Couldn’t explain an egg to those subscribers... it’s a hoax!

[@arthurlewis9193]

Do you get a bit pissed off with youtubers like JoneS SenoJ (and others) using your videos to prove that jet turbine engines run on air and require no fuel?

[@AgentJayZ]

"prove"? Are you trolling, or just another flat earther? The jet fuel hoax theory is one of life's intelligence tests, and those people are failing... again.

[@arthurlewis9193]

Whoa! Slow down cowboy. I was just letting you know that there are idiots out there (like the one I mentioned) using you work (which I enjoy) to suggest it "proves" jet turbines run on compressed air. I wish I hadn't bothered now.

[@pudmina]

+Arthur Lewis - The problem is that the way your comment is worded, without some sort of indicator such as an emoticon, smiley face ;), /sarcasm, etc it's hard to tell which side (A: Normal or B: Tinfoil Hat) of the fence you are on. I believe the video you are referring to is kzbin.info/www/bejne/mKWviGijaK-Wl6s and I seem to recall a comment in this or another of Jay's videos to the effect that he is aware of this misuse and probably not happy about it. This TFH dork Jones Senoj basically implies that Jay is part of a world wide conspiracy to rip off aircraft passengers everywhere for fake fuel consumption. I think anyone in this circumstance would be PO'd.

[@unexpectedcaveman6573]

Yeah, I was just coming here to say that Jones seems to think you're on his side, and yes, I think this whole jet engines running on air is pure bullshit.

[@pudmina]

+Piltdown Flan - Yup ... Jones is deluded about a wide variety of concepts. But apparently you are a fraudulent pastry :)

[@peterbustin8604]

Where would you be without us Brits ? Ha Ha Ha

[@AgentJayZ]

Please, let us all know what great honor you are personally bestowing upon yourself...