How to start a jet engine

[@aspret]

Thanks so much for this video. ALL other "how-does-a-jet-engine-work" videos ignore this very important starting point, leaving viewers ignorant. Well done AgentJayz :)

[@matthewkevinkumar2969]

Man ! u r the best Turbo machinery guy on KZbin ! I don't know if ur father or brother is a turbojet engineer or not but the exposure u have to turbojet engines is HUGE and what takes u to the next level is ur willingness not to JUST share it on KZbin for views but to share it in a clear cut novice manner ..... Awesome , keep it up !!!

[@FishAdvisor]

Why would anyone dislike this video? There's nothing to dislike. Straight forward and simple! Total opposite of the actual engine shown!

[@m1leswilliams]

Yeah simple... we start a jet engine with a jet engine.

[@thomasburke7995]

30 years in aviation on the ramp side.. worked with everything from jt3/4 's to cfm's to rb211 to pt8's and the venerable DARTS. have heard many starts but this explanation was excellent. . sucke squeeze bang blow..

[@rathishatutube]

I was totally confused on how the jet engine starts initially by what powers the turbine to rotate.. Now its clear that only with external air supply... Thank u very much

[@thephysicsguy181]

This video is so educative you have no idea. I had to go to the library on a friday night to suffice my curiosity. Thanks for the content!!

[@conradeckstein2884]

When I worked on the SR 71 in the 1960s, it was really fun. Our start cart had 2 Buick 401 Wildcat V8s with open headers. My ears are still ringing.

[@AgentJayZ]

I guess you're the expert, but the books I've read say the engines were 455s.

[@conradeckstein2884]

Hardly an expert, and it's been 50 years. I have read that the Buicks were swapped out for Chevy 454s in the mid 1970s. What I do remember is how exciting it was to pull down on that throttle and hear that J 58 come to life. If you did it wrong the pilot could get very upset. The probe could drop out on a 'hanging start' and everything had to coast down. They had a tanker to catch! I really enjoy your channel. You are the undisputed expert!

[@BretABennett]

HI AgentJayZ et al, I'm neither a pilot or aircraft mechanic, but I really enjoy your channel and learning how turbojets (and turbofans) are put together, how they work, are rebuilt, and maintained. As a child I spent many hours at a grass runway with my Dad. He was a private pilot and had served in the US Air Force as an aircraft mechanic. He even towed home a Taylorcraft one time (wings off and the tail wheel in the car trunk), put a new skin of ceconite on it, and sprayed it bright yellow, right there in our home garage. I must have inherited my flight genes from him. I also subscribe to Mentour Pilot and enjoy the cockpit side of the story too. Captain Petter just did a piece on 12/6/2019 titled "Sucked into a Jet engine?". Since we're all interested in jet engines, I thought you and your subscribers might enjoy watching that one particularly if you've not seen it yet. It's over at: kzbin.info/www/bejne/ommyYomNYql-d9E Thank you and your team again for the dedication to your profession and sharing your knowledge and enthusiasm! Regards . . .

[@LadyMoonstar6601]

super cool! having autism and loving engines of every type and researching about them and how they work, I found this video extremely informative and satisfying to watch. Thank you

[@bigredc222]

Your video's are great, Thanks for taking the time to make them.

[@eaglegrip6879]

The SR-71 was started with a cart that had 2, 454 CI, super high performance Buick engines mounted on it. Both engines worked simultaneously to rotate a large gear extremely fast. The gear turned over the jet engines until they started and ran by themselves. Pneumatic start carts like the one seen here, just weren't strong enough to crank over an SR-71 (J-58) engine.

[@AgentJayZ]

The engines were stock 455 wildcat Buicks. Each engine was started individually. There is one of these start carts on display, along with an SR-71 that you can sit in, at the Boeing museum in Seattle.

[@74superglide]

@@AgentJayZ later on they used 454 engines

[@bigdaddy7119]

Douglas Oakley Buick didn’t make the 454 though, Chevy did

[@eaglegrip6879]

@@bigdaddy7119 You're right. Sorry. I meant to say "455 wildcat engines." My mistake. It's been over 40 years since I worked on the SR-71. Thanks for the correction.

[@kristov29]

Clear and concise. Than you for taking the time to explain it all.

[@yashgupta2940]

Finally found the right video, been searching how does the engine starts but couldnt find the appropriate video, thanks man🙏

[@AgentJayZ]

For other mysteries, try putting the subject into the search bar on my channel page. Might have made a video on it already.

[@mannypuerta5086]

The biggest difference I noticed between starting an older engine like a JT3D and a newer one like a CFM56 was that you had to talk to the CFM56 during the slower start process. The JT3D started like an old Chevy Six and the CFM56 seemed like it needed coaxing, encouragement and patience. Both great engines in their own right, though. Some folks might also be interested in hearing about a cross-bleed start.

[@AgentJayZ]

Yes, that's true if you are watching one of my videos, and we are using the air turbine starter. That's most of them. The Olympus uses a hydraulic starter, and the J47 uses an electric starter.

[@AgentJayZ]

@dave4shmups The actual engines used inside APUs built into airliners are the same as those built into ground power units. Our start cart has a Garrett GTC85 for an engine. The same unit was built into 707s and 727s, as well as many other aircraft.

[@AgentJayZ]

To quote the gunshop owner in Terminator: Hey... just what you see, pal.

[@AgentJayZ]

@blobusus The lightest, most self-sufficient method of starting a jet is with a gas-generating cartridge powering a small turbine starter. It's similar to our air turbine startr, but designed for higher temperatures. And instead of the start cart, the starter is supplied gas from one or more cartridges on board the plane. for an example, search for Canberra cartridge start.. The Canberra has Avon engines, very similar to the industrial Avons we test.

[@AgentJayZ]

The part of the 747 engine you are turning so easily is the LP system, and it does not drive any of the auxilaries, like fuel pumps, oil pumps, generators, etc. It also is not the part of the engine turned by the starter. The part that needs to be spun up to start the engine is the HP system, and you can't reach that from the outside. "all that is needed" is to get the HP system, or "core" back up to minimum starting rpm. This is only possible at certain airspeeds and altitudes.

[@AgentJayZ]

@sephiroth1349 I'm not sure if your engines have air impingement or air turbine starting, but one thing is for sure: Whatever the air from the APU does, the GPU supplies it to the same place. Basically the only difference between an APU and a GPU is that the GPU has wheels. For example, a B727 has an onboard Garrett GTC85. Our start cart is a Garrett GTC85.

[@mikeall7012]

we started our aircraft off the aux power unit, which was a small turboshaft on the aircraft. we only used the ground cart for maint. the apu started from hydro pressure

[@AgentJayZ]

different planes have different starting procedures, but whatever they use, it's always that way. I think fighter jets on active duty all have their own start cart, always waiting right there beside them. Also a few spares nearby in case there are any problems. As you can see from my videos, the start cart can go from not running to having the jet at idle in about 2 minutes. The only way to get the jet started faster would be to have the start cart constantly running. Maybe that is done.

[@vezzosetto]

Your videos are brilliant and always very enjoyable to watch!

[@AgentJayZ]

Yes, we've discussed this before. The stranded one was likely hot-started, causing engine damage, and I would bet that Chuck was the only one who could get away with such a thing. I doubt it's ever been done since.

[@theduder2617]

Well that explains the answer a pilot gave me years back when I asked how a jet engine was started. He said "With a running jet engine". In a way, it seemed a lot like the egg vs chicken debate for an answer. lol Thank you for this explanation. Imagine for a moment if these engines were started via pull cord somehow. "Who wants to start the jet?" 123 NOT IT! lol

[@BeechSportBill]

ME 262 had a gas engine starter...

[@raimo5091]

Airliners rarely use ground air starter unit or engine cross bleed. Only when APU is unservicable or not practical to use. Each engine is started by APU bleed air.

[@AgentJayZ]

@Pyanities Yes, there is a centrifugally activated clutch that disengages the starter at about 2500 rpm.

[@AgentJayZ]

Batteries power the electric motor used to start the gas turbine engine in the start cart, which supplies air to the small power turbine in the starter of the LM1500, which turns the main shaft of the LM1500...

[@AgentJayZ]

Only one angle drive meshes with the main rotor. It drives the only radial driveshaft passing through the 6 oclock strut on the fron frame. At the bottom of that is the main gearbox, containing another angle drive, which makes all the gears spin in the same plane as the main rotor, just 2.5 feet below it. Connected to one of the spinning gearshafts in the gearbox is the starter drive.

[@AgentJayZ]

@cheetawolf Yes, those 4 things are projections into the gas path, and I have no idea why they are there. They are not big enough to be any sort of aerodynamic device, and they are not connected to any air lines for sensing pressure, nor are they connected to any liquid lines which might be part of a washing system. I'm only guessing, but I think they are blanking plates for what would normally be a water wash system. Not needed in a test cell.

[@AgentJayZ]

@VERGIS92 On the ground, anything is possible. You'd need a fairly large electric motor. Something that would provide about 500 lb-ft of torque, and not overheat if it took twenty seconds or so to get up to about 1000 rpm..

[@AgentJayZ]

@dave4shmups A turboprop is a combination of a small gas turbine engine (1-5 thousand Hp), mated to a power turbine(usually) driving a gearbox which reduces the speed of its output shaft ( and increases its torque), to which is attached a propeller. An exception is the Garrett TPE-331, which drives the gearbox with the main shaft of the engine; no power turbine needed. So, starting a turboprop is exactly the same as starting a jet engine: RPMs, ignition, and then fuel.

[@coachman64506]

Dang, and I thought he was going to start the engine

[@AgentJayZ]

Need... to ... open... eyes, and click... just one... of his... engine... test run... videos...gasp! Hundreds of 'em...

[@michaelmilburn1024]

AgentJayZ hello I’m Michael Milburn I live in wayland mi. I like your videos on those jet engines it’s a interesting learning thing you show us I’m wondering if you can send me a memberbilia such as that one hooded sweatshirt you wear in some of the videos my address Is 1175 eagle drive wayland mi 49348 apt 104 if you can do that that will be ausome my wed address is Michaelmilburn75@ Gmail.com thanks bro you rock keep up the good work

[@sitimaria8976]

Yjhjg

[@jrkc9218]

Once again, I really appreciate your videos. Learning all this stuff took my fear of flying away. Educational. Thank you

[@AgentJayZ]

@fmeriqui Yes, I didn't mention that. Our start cart is basically an APU on wheels.

[@AgentJayZ]

Silly but true... although nowadays, the "external" help is an on-board APU that can be started using aircraft batteries.

[@AgentJayZ]

@mightyfinejonboy Don't know if it has a name. With our tests it seems to be the resonation of the jetpipe cused or influenced by the heat. It doesn't come out on video, but our vaporizer makes a thunderous bass tone. It has an exhaust stack about 24 inches diameter and 25 feet tall. It's shown in a couple of my videos.

[@AgentJayZ]

Hey, pal... I stick to showing people what we do, and what I know. 90% of our engines are started with the turbine start cart and the air-turbine starter. Occasionally we have a hydraulically started Olympus in our test cell... which we start with a hydraulic motor. And once in a while we have an electrically started engine... which we start with an electric start cart. Didn't I cover that in the video?

[@whorayful]

Ray here, N1 is gas producer speed in a split shaft engine. This is an engine whose exhaust gas 'blows' or pushes the power turbine blades around, the power turbine (N2) drives the external connected load. This is standard arrangement in helicopter and small industrial style machines under about 1MW. The term 'multistage' refers to the number of compressor and turbine blade discs in the engine. A typical small industrial may have 7 stages of compression blades followed by 3 turbine stages.

[@AgentJayZ]

Yes, you are right, and some modern engines are using electric starters again. We work on engines, and have little contact with the aircraft, so I can't really answer your question.

[@c.s.5240]

Excellent explanation. Igniter box energized 500 rpm, Around 1500 rpm fuel on ignition start, at around 3000 rpm minimum self-sustaining rpm, starter off, 5000 rpm idle. Do those figures vary much with other engine models or with turbo fans?

[@whitey792000]

very nicely done video. I am a master auto diesel mechanic and I never knew how a jet engine started. Thanks for the info.

[@alvislancaster5967]

I worked at test cell at nellis afb....ran the engines for the f15 and f16 jets....a lot of fun and noisy....how he started this was the same way...

[@TheBergernator9]

What an informative video. Its always great learning about machines that we use everyday and take for granted. Thanks for the upload

[@AgentJayZ]

@Airtran9906 I've got a video or two up featuring an electric start Avon, and a couple featuring a hydraulic start Olympus...

[@M-28xD]

But you didn't start it :(

[@AgentJayZ]

... dozens of engine test videos posted where we use the start cart to wind up and start a jet engine... have a look.

[@M-28xD]

I was just making a joke mate:) thanks some nice stuff you got there! have a great day

[@shirinmuchhala2082]

AgentJayZ

[@JR-ly8iz]

So, now I got to know how engines start with the help of bleed air of the APU in commercial jets! Thanks for the video!

[@w4447]

great video I always wondered how they start those things on the tarmac.

[@AgentJayZ]

In some combinations of airspeed and altitude, an engine can be started with the air moving through it. Not an easy thing, though.

[@oscarb9139]

The airlines use bleed air from the APU to start the engines. If the APU, or the bleed from the APU is inoperative, we use a start cart to start the first engine, and then cross bleed start the other engine(s).

[@AgentJayZ]

Yeah, I think we covered that. Ten years ago. But you are absolutely correct, sir!

[@oscarb9139]

@@AgentJayZ You are welcome (sincerely). My comment was for non-aviation types who might have been watching this video. Not everyone watches every video you create.

[@mashedtomato2079]

@@oscarb9139 Thank you veey much, I need such information as Im studying for tests.

[@oscarb9139]

@@mashedtomato2079 Sure thing. What tests?

[@mashedtomato2079]

@@oscarb9139 Airframe and Powerplant licenses

[@lekoman]

I can see this quickly becoming one of my new favorite KZbin channels. Just this one video alone (although I understood in principle before I got here) was excellent. Well described, sir! Thanks, and subscribed! :)

[@61espo]

Thanks for the videos! We love em here in NY!

[@thomasuhl7818]

Good presentation, you deserve being commended for your presentation. :)

[@AgentJayZ]

Being a much smaller turbine engine, the start cart uses two car batteries to supply power to its 24VDC electric starter.

[@dwightlooi]

The GEnx is electric start. There is no bleed air and no air turbine. The accessory gearbox drives a generator. This generator also functions as an electric motor to turn the high pressure shaft for starting the engine. Electric power is provided by one of two Lithium Ion batteries or by the APS5000 APU.

[@faresautobiography2365]

I been watching you tube to understand the process of jet engine working, non as good as this THANK you for this

[@BillyN31]

I love your videos so much! Thank you for taking the time to do these.

[@testando6655]

Totally an aviation nut myself! Dis guy right here always watch the plane video from here with my rock playlist crancked to 11. Metallica, Delta Parole, ACDC etc. AWESOME!

[@AgentJayZ]

If the starter is assisting the engine in gaining speed , it isn't being driven by the engine... it is still driving the engine. Once the engine reaches about 3000 rpm, a centrifugal mechanism disengages the starter clutch.

[@alexanderrosalez8797]

The way you explain it, it almost sounds like you're running ignition for a while before you shoot fuel. I hope I'm wrong there, sounds wasteful. And im curious, if the apu is running, can that start the mains?

[@AgentJayZ]

The start sequence is always rpm, spark, then fuel. Adding fuel before ignition is a guaranteed boom, and a very likely destroyed engine. Wasting sparks? Nope. Once the engine is running, the ignition is turned to OFF. For the whole time the engine is running, and that can be literally years, non-stop. In an aircraft, the APU is often a potential source of starting power.

[@alexanderrosalez8797]

Makes total sense.... and you explained it at the end... duh. I dont know what I was thinking when I typed that... but the apu question I really didn't know about but does make sense watching that again and you saying the other engines can start one... Thank you!

[@stustu4231]

Who’d have thought when I used to work with you at TCT I’d be watching you years later on KZbin!

[@AgentJayZ]

Such a great place to escape from!

[@AgentJayZ]

@dave4shmups Yes, that's exactly what we use here...

[@lorenzomaximo1818]

We called the jet engine starter in the Navy a huffer. I worked on Pratt & Whitney tf30 p408.

[@AgentJayZ]

Always good to hear from someone who was there, in the days when these things were in their prime.

[@lorenzomaximo1818]

@@AgentJayZ Thanks for compliment I worked on A 7 Corsair IIs during the Vietnam war. With VA 155. Involved in operation linebacker and linebacker 2 that brought the North Vietnamese to the bargaining table.

[@davidfaiheng]

Always wondered what makes turbines spin in the first place. Thanks for clearing this up.

[@johnmoore8016]

Started LM2500 many a time with bleed air from the GTG, Using the auto start mode done manual start when the PM book called for it. (didn't know they made an LM1500. (Mississippi gulf cost, USA)

[@AgentJayZ]

Many larger aircraft have an on board APU that can supply air or electric power to start the main engines.

[@AgentJayZ]

Actually, the starter is cut out well before ground idle, which is roughly 60% full rpm. Flight idle is the lowest speed the engine would see... in flight, and is roughly 85% full rpm. The few words I might say about starting a car engine are: this has nothing to do with starting a gas turbine engine.

[@happyduckling]

Thank you for this video. I was waiting for this kind of explanation for a while. Finally, you made it clear.

[@MelindaColden]

that was really helpful, thank you! now i can finally start my jet engine

[@AgentJayZ]

@sephiroth1349 I'm not familiar with the APU in a 757, but I'll bet a paycheck that it's a small gas turbine engine, designed to supply excess compressor bleed air as one source of power, as well as turning a generator to provide a source of electrical power. The APU can be started with on-board batteries, because two normal car batteries have plenty of juice for that job.

[@roastysprouts1004]

Great vid, explained a lot more than I initially intended to learn. Thanks!

[@ryanhat5328]

I just asked you a question about this on another video VERY INTERESTING I am very surprised a jet engine can not start under its own power I assumed they used onboard electric motors powered by batteries to spin the turbines up to that initial idle speed. Some of the best videos I have ever seen on KZbin. Thanks again

[@hotwheelz01]

dude that was exactly what i wanted to know, straight to the point. that one gets a like

[@deronborghi5929]

This took me back to my flight line days, Thanks

[@letitrest4662]

At the gate prior to push back, and during boarding,the aircraft cabin environment systems(packs), are not running. The cabin is cooled or heated by the jetway's system that's connected to an external ground air port, on the plane. Prior to bush back, the jetway air system is shutoff, after the APU is started up. The APU provides pneumatic air to run the packs, that heat, or cool the cabin. Also the APU provides high pressure/ high volume pneumatic air, to start the first engine. The engine that gets started first, is the one that provides primary nose wheel steering, and brake hydraulic pressure.You'll notice, if on the plane, during pushback, that just before you hear one of the main engines start to motor for the starting sequence, that the air conditioning shuts off. That's because the aircraft system sends all available APU pneumatic air to the engine starter, and disables any air that runs the packs.

[@geovanireis4472]

after the turbine is fully functioning, do the spark plugs for the combustion chamber continue to generate sparks or the fire that is already there to keep combustion?

[@AgentJayZ]

Like a candle, once it's lit, there is no longer a need to strike a match.

[@cisarvialpando7412]

Good question. Now it clear my doubts...

[@EinkOLED]

I've been in a Boeing 737-800 that used a cross bleed start. This was probably due to problems with the APU as the first engine needed a compressor for start, After push back with the first engine running the aircraft increased in thrust which shook the aircraft for a few seconds until the second engine wind milled. I knew exactly what was happening and enjoyed understanding just how much thrust is needed to to transfer 30 psi to the other engine.

[@rogerpemberton79]

I maybe completely wrong but most jet airliners have an APU (Auxiliary Power Unit) that is used to spool up their engines. The APU again if I'm not mistaken can also assist in relight should an engine flame out in flight. Although if just one engine flames out the remaining engines can be used to power the dead engine back to life if possible. I'm not saying all jet aircraft are that way but most modern heavy airliners are to my knowledge.

[@AgentJayZ]

You are not wrong. The engine in our start cart is the same as the APU in a Boeing 727.

[@abhijitb4448]

Very Nice Explanation, I struggled to know how does it actually starts OR what makes a front big fan to rotate. Got the answer. Thanks!

[@roberte8656]

Really clear explanation!! Thanks for sharing!

[@sgoell75]

Thank you for all your time posting this and all your videos

[@RealSaladsamurai]

:: "WRONG" ::end Terminator quote:: .... But seriously, as an engineer working in the aviation industry (for a company that manufactures many of the engines you are demonstrating here) I have learned so much from your videos. It's tough not getting to see most of things that I work on up close and personal. Your videos have been serving to fill that void. Thanks and keep up the great work. Maybe I will get to visit some time.

[@MTAviationPhotoFilm]

Airlines have APUs that have there own battery for starting the apu. The huffer cart comes into play when the apu or APU LCV (load control valve) is deferred. Its more common with regionals then the mainlines.

[@Naton]

I once had a lecturer from the military told me about the "Buddy Start". placing a 'running' engine's exhaust facing another engine's compressor which needs to be start. not sure if its true, but it sure is one heck of an idea only found in military.

[@AgentJayZ]

@mman454 Fuel does not "build up" it is fed into the airstream in the presence of an ignition souce so it can burn and produce heat, which causes the air to expand, which does work on the turbine. Fuel and ignition in a non-rotating turbine engine equals fire and a very expensive trip to the shop. ... a show? I guess that is anything that entertains people.

[@mamiller1980]

So if this was a commercial jet, the start cart would be the APU and the output air switch is the bleed air used to start the engine?

[@hyburn78]

Perfect mate, exactly what I was looking to understand.

[@strongerhitman]

thank you for the video, i worked for the airlines for 6 years and i was the leader on the airstart team, there is nothing like jump starting a airbus 330

[@theundertow09]

We can use start carts, but primarily we use the aircrafts APU or JSF (jet fuel starter) to get them up and running. Same concept as a start cart, it's just built into the aircraft.

[@razgriz786]

Hi I'm studying Aircraft Maintenance at Centennial college in Toronto. You're videos are very helpfull!

[@DazUK81]

Watching this before I go to work because I'm a painter and decorator and need to know these things........

[@kevin6719]

your videos rock.. thanks for sharing..

[@Mach1Airspace]

“And we don’t like bangs”. The understatement of the century.

[@Moaath13]

You are a living LEGEND

[@eatonbeaver6083]

Most modern airliners have what is called an APU, or auxiliary power unit. It is most commonly found in the tail of the aircraft although some may be mounted near the center of the aircraft with the exhaust routed out the side. It is basically a small turbine engine not unlike what is in his yellow start cart. In addition to providing electricity to the aircraft during the times the main engines are shut down it also provides the bleed air needed to start the main engines and for air conditioning. It is usually started when the aircraft is taxing to the gate and shut down after a cool down period once it is unloaded and diring taxi for takeoff. Often times passengers riding in a 727 just behind the wing could sometimes see a small jet of flame as the APU was started. I have also seen start carts that were powered by 8 cylinder Detroit diesels running compressors istead of small turbines.

[@thictedd186]

Great! Now i can try it myself!

[@supercarsvloggerireland2991]

Very interesting video, I've always wanted to know how a jet engine starts.

[@soillife1]

We wanted to hear it Start

[@AgentJayZ]

That is in all of my many, many engine test run videos...

[@royevans4581]

Excellent video. I was guessing how you did it until now. Thought it was an electric motor but now i know ))

[@davidjohnny3412]

Ok I'm sorry I have an actual question. In your engines and commercial engines such as cf6-80 and ge90... Is full thrust ever used or is there a limitor?