Great demo. In the 1970s I was a mechanic at an airline operating aircraft with P&W JT-8D engines, and I became quite familiar with the igniters. If I remember correctly, they produced about 12 Joules of energy per spark. Standing beside a dry-motoring engine with ignition on, you could clearly hear each spark inside the engine. In the accessory shop, the igniters were fired inside a plexiglass tube open at the end to protect the worker. Each spark was about as loud as a .22 pistol shot. After seeing this, there was little need to warn people about how dangerous these things are.
Yes, you and @jakem7838 are correct. Larger jet engines have slower igniters activation. This small igniter is from an APU and normally fires at the fast pace as shown in the video.
@@justenlimbecause the start sequence is quicker AND as mentioned the energy requirements aren’t as high which means the capacitive components don’t need to charge as long.
Note to techs and others: Recently found WATER in the igniter leads.....on TWO different aircraft. We can only guess how it got in there. Our guess is that the engine wash was not done properly. We all need to be reminded to do things by the book. If there is an op check after the wash.....don't skip it. It's there for a reason.
I've tested them in situ, I've replaced them but because of the voltage and current involved I've never seen one firing. Nice to put a picture to the noise.
I am an electrical engineer and during the past 5 years, I have used, studied, opened up and actually designed and built equivalent units using modern electrical components. Firstly and most importantly they are seriously dangerous and will kill you if the electric current travels between your hands across your heart. Before touching or opening them up leave them unpowered for at least 15 to 30 mins. So now to their internal workings. Essentially internally they are all very similar generating about a 3000 DC voltage (in different ways) charging a large special HV mica capacitor. When the voltage reaches about 2800V (give or take) a sealed glass tube with a spark gap conducts, dumping the stored capacitor energy to the igniter plug. The end of the igniter plug tip is surrounded by a semiconductor substance which ignites with a plume of flame. Its not a conventional spark plug as found on a motor car. If you measure the resistance of a motor car spark plug it will show infinite resistance, whereas a jet igniter plug measures around 20K to 50K ohms. These igniter plugs will fire submersed in water! As stated earlier the HV DC is generated in different ways. Early igniters around 1960's operated on 24 or 48V DC and used a transformer with a vibrating reed switch to interrupt the primary winding, thus generating a larger secondary HV voltage which was rectified using a HV diode to charge the capacitor. Later units used a switching transistor on the primary. Other units simply used the aircraft 400Hz AC power directly into the igniter transformer to generate the HV secondary. The units fire at different rates, some twice a second, while others once a second. Out of interest, designing a modern version was quite difficult as obtaining equivalent small mica HV capacitors is almost impossible these days, so my units where significantly larger but worked identically.
Quick question, do they spark continuously until engine shutdown. I always thought that once ignited the fuel would be introduced and self burn due to high pressure and continuous inflow.
@@colinashby3775 Gooday from Sydney Australia. Firstly let me add a minor correction to my comment. Some of these high energy igniters can spark up to 4 times per second. Now to your question, we have a number of jet engines including a Turbomecca Marbore 4, Rolls Royce Nimbus, Alison 250 and a small auxiliary turbine engine from god only knows what it came from. On these engines, the igniters begin sparking the moment the starter motor is engaged.. For example on the Turbomecca when combustion pressure is detected the starter motor disengages and the igniter is turned off. On the others it can be exhaust temperature detection or some other method. In summary the igniter generally turn off when either combustion is detected and or idle is achieved. I cannot comment on other aircraft engine behavior, but these high energy igniter are definitely not meant for continuous operation.
After start the engine rpm stabilize and combustion is self sustaining they get turned off. Many engine manufacturers require they be on in flight during heavy rain and/or icing too.
I guess those ignitor plugs glow for some seconds during initial start up of jet turbine to burn the fuel air mixture that's being pumped in to the turbine and when fuel air mixture's ignition happens as well as self-sustains itself like a " kitchen gas stove after being lit " then those electric ignitors turn off right ?
@@hayleyxyz You would think so, but that's not the case. There are times the igniters are turned on specifically and times they come on automatically. @jakem7838 comment is correct. They also should be turned on when in turbulence and come on automatically when the engine anti-ice is turned on. We run them for hours at a time. No ill effects.
The 3 concentrated blue flames are not aligned with the fuel nozzles, is this normal or was this just a test type of thing with propane or something?? Do the flames propagate from the nozzles when used with jet fuel or do they kind of hang between them because of the airflow?
Igniters are like spark plugs. They have a ceramic core. A cracked core will let the spark jump inside the igniter, preventing it from sparking at the tip. Just FYI.
It's good to hear from you. I was actually thinking about you and some of the other people from the PAV contest, a few weeks ago. Wondering if anyone was continuing to build their version of PAV after the contest. I have been working on my family and career mostly, but I am also revisiting my PAV design. I have some new equipment, and I am currently building a prototype engine. Not sure if it will work. How about you? How are you doing?
@@shadojet3868 i had even forgotten that you had a channel or that i had subscribed. but perchance you uploaded some videos and showed up in my feed. No - ive done nothing with PAVs. just building my model planes. I follow whats happening and to be honest despite some people flying around - essentially the only reasonable one is Richard Browning with his turbine packs. But most notable - nobody is buying PAVs so how many years has it been, maybe 7 or 8 and essentially its a stagnant avenue. Are you on facebook or whatsapp?
@@deonjansen No, I am not on Facebook or WhatsApp or any other social media like X or Snapchat or whatever. I am mostly too busy to keep up with all the social media apps. Only decided to return to RUclips a few days ago. So far, I have received good comments. I really appreciate it.
@@shadojet3868 ok well, maybe email then, Im sure i must have had your email, and im sure you have mine. will be good to chat, and yes - keep on doing the youtube videos for sure
The combustion chamber cool air path cools the igniters during engine operation. The cooling air is what surrounds the burner can and controls the burner flames.
Always wait for the required time after turningbthe system off, and pull the breaker. The amps the system throws out of the capacitor can and will kill you. Read the manual and observe!!
Great demo. In the 1970s I was a mechanic at an airline operating aircraft with P&W JT-8D engines, and I became quite familiar with the igniters. If I remember correctly, they produced about 12 Joules of energy per spark. Standing beside a dry-motoring engine with ignition on, you could clearly hear each spark inside the engine. In the accessory shop, the igniters were fired inside a plexiglass tube open at the end to protect the worker. Each spark was about as loud as a .22 pistol shot. After seeing this, there was little need to warn people about how dangerous these things are.
So much for the old GM HEI coils used on auto engines in the '80's. I need one of these spark generators for a project….
Wondrous indoor pyrotechnics never cease to satisfy. You are more brave and have better insurance than me.
excellent, an interesting video about something I haven't thought about before, and without stretching it to 15 minutes as most youtubers do
Those igniters fire crazy fast. On every airliner I've ever worked they fire about once per second. Snap.....snap.....snap.
Larger engines require more energy through the plugs. Takes longer to charge up the exciter coils.
Yes, you and @jakem7838 are correct. Larger jet engines have slower igniters activation. This small igniter is from an APU and normally fires at the fast pace as shown in the video.
@@jakem7838 I wonder what the pressure is in the combustion chamber when they first light off.
@@shadojet3868 why do smaller engines need faster pace?
@@justenlimbecause the start sequence is quicker AND as mentioned the energy requirements aren’t as high which means the capacitive components don’t need to charge as long.
Wow, great! Finally some visual impressions of what others only speak about!
Note to techs and others: Recently found WATER in the igniter leads.....on TWO different aircraft. We can only guess how it got in there. Our guess is that the engine wash was not done properly.
We all need to be reminded to do things by the book. If there is an op check after the wash.....don't skip it. It's there for a reason.
Probably introduced through the air shroud of the ignitor leads.
Thank you.
I've tested them in situ, I've replaced them but because of the voltage and current involved I've never seen one firing. Nice to put a picture to the noise.
Fantastic - thank you! As a side note - that would be excellent for heating up a Wok =)
I am an electrical engineer and during the past 5 years, I have used, studied, opened up and actually designed and built equivalent units using modern electrical components. Firstly and most importantly they are seriously dangerous and will kill you if the electric current travels between your hands across your heart. Before touching or opening them up leave them unpowered for at least 15 to 30 mins. So now to their internal workings. Essentially internally they are all very similar generating about a 3000 DC voltage (in different ways) charging a large special HV mica capacitor. When the voltage reaches about 2800V (give or take) a sealed glass tube with a spark gap conducts, dumping the stored capacitor energy to the igniter plug. The end of the igniter plug tip is surrounded by a semiconductor substance which ignites with a plume of flame. Its not a conventional spark plug as found on a motor car. If you measure the resistance of a motor car spark plug it will show infinite resistance, whereas a jet igniter plug measures around 20K to 50K ohms. These igniter plugs will fire submersed in water! As stated earlier the HV DC is generated in different ways. Early igniters around 1960's operated on 24 or 48V DC and used a transformer with a vibrating reed switch to interrupt the primary winding, thus generating a larger secondary HV voltage which was rectified using a HV diode to charge the capacitor. Later units used a switching transistor on the primary. Other units simply used the aircraft 400Hz AC power directly into the igniter transformer to generate the HV secondary. The units fire at different rates, some twice a second, while others once a second. Out of interest, designing a modern version was quite difficult as obtaining equivalent small mica HV capacitors is almost impossible these days, so my units where significantly larger but worked identically.
Quick question, do they spark continuously until engine shutdown. I always thought that once ignited the fuel would be introduced and self burn due to high pressure and continuous inflow.
@@colinashby3775 Gooday from Sydney Australia. Firstly let me add a minor correction to my comment. Some of these high energy igniters can spark up to 4 times per second.
Now to your question, we have a number of jet engines including a Turbomecca Marbore 4, Rolls Royce Nimbus, Alison 250 and a small auxiliary turbine engine from god only knows what it came from. On these engines, the igniters begin sparking the moment the starter motor is engaged.. For example on the Turbomecca when combustion pressure is detected the starter motor disengages and the igniter is turned off. On the others it can be exhaust temperature detection or some other method. In summary the igniter generally turn off when either combustion is detected and or idle is achieved. I cannot comment on other aircraft engine behavior, but these high energy igniter are definitely not meant for continuous operation.
@ thank for this from South Africa. Good to know not to touch them. Never realised they were that strong.
After start the engine rpm stabilize and combustion is self sustaining they get turned off.
Many engine manufacturers require they be on in flight during heavy rain and/or icing too.
We would turn on the igniters in heavy precip so that the flame would not be extinguished.
Thank you for answering the question! I would also add that pilots are required to turn on the igniters in icing conditions. Thanks again.
@@shadojet3868
That's a company requirement, but it's a good one to have.
That was cool. This needs more views.
I never considered how this works before. Interesting!
Thank you so much for your explanation
Excellent illustration. Thanks.
I guess those ignitor plugs glow for some seconds during initial start up of jet turbine to burn the fuel air mixture that's being pumped in to the turbine and when fuel air mixture's ignition happens as well as self-sustains itself like a " kitchen gas stove after being lit " then those electric ignitors turn off right ?
You had me at "jet engine project".
Thankyou Sir Frank Wittle
Nice stove too 😅, thanks buddy, always wondered wtf is all that noise on runways.
Super Cool! Keep up the Awesome work!
is it necessary to keep the spark on during all the time, even after the ignition begins?
Not usually. I left it on for the video demonstration.
That was the question I was going to ask. Good to know.
The igniter would burn themselves through very quickly if they were left on.
When flying through moderate to heavy precipitation, both ignition systems are usually on continuous mode, to prevent flame out.
@@hayleyxyz You would think so, but that's not the case. There are times the igniters are turned on specifically and times they come on automatically. @jakem7838 comment is correct. They also should be turned on when in turbulence and come on automatically when the engine anti-ice is turned on. We run them for hours at a time. No ill effects.
Amazing video, thanks
This is going to make for a wicked marshmallow roast😁
Nice video.
Wow you and agent jay z right up there
!!!
Thank you, but really Jay Z is far more knowledgeable than I am.
The music makes this whole video seem goofy. 😂
The 3 concentrated blue flames are not aligned with the fuel nozzles, is this normal or was this just a test type of thing with propane or something?? Do the flames propagate from the nozzles when used with jet fuel or do they kind of hang between them because of the airflow?
1. Chitty 2. chitty 3. bang 4. bang
Had one fail on a Citation jet in the '80's and I wonder what is the failure mode on them? Do they go open circuit or do the fowl or burn up?
Igniters are like spark plugs. They have a ceramic core. A cracked core will let the spark jump inside the igniter, preventing it from sparking at the tip. Just FYI.
@@shadojet3868 Thanks!
Thats a heck of a cooking pot
I have always wondered, does the igniter plugs stay on during the entire operation of the engine or is it self sustained afterwards?
Only used for ignition and startup like a diesel glow plug.
During heavy precipitation they are left "on".
Some pilots will turn them back on if they may be flying into heavy rain or snow just to feel a bit better in case there's a flame out
Nice. Hows it going - havnt chatted to you for ages since the PAV designs
It's good to hear from you. I was actually thinking about you and some of the other people from the PAV contest, a few weeks ago. Wondering if anyone was continuing to build their version of PAV after the contest. I have been working on my family and career mostly, but I am also revisiting my PAV design. I have some new equipment, and I am currently building a prototype engine. Not sure if it will work. How about you? How are you doing?
@@shadojet3868 i had even forgotten that you had a channel or that i had subscribed. but perchance you uploaded some videos and showed up in my feed. No - ive done nothing with PAVs. just building my model planes. I follow whats happening and to be honest despite some people flying around - essentially the only reasonable one is Richard Browning with his turbine packs. But most notable - nobody is buying PAVs so how many years has it been, maybe 7 or 8 and essentially its a stagnant avenue. Are you on facebook or whatsapp?
@@deonjansen No, I am not on Facebook or WhatsApp or any other social media like X or Snapchat or whatever. I am mostly too busy to keep up with all the social media apps. Only decided to return to RUclips a few days ago. So far, I have received good comments. I really appreciate it.
@@shadojet3868 ok well, maybe email then, Im sure i must have had your email, and im sure you have mine. will be good to chat, and yes - keep on doing the youtube videos for sure
Very cool ! I should have went the aviation route rather than diesel tech. Much more interesting !
Really cool i like
Can you imagine......the igniter sits there during hour after hour of engine operation. Like being in an oven.
The combustion chamber cool air path cools the igniters during engine operation. The cooling air is what surrounds the burner can and controls the burner flames.
That was cool
Can I get one of those for my crab broiler? 😂
Very nice presentation. But there is some strange noise in the background, like someone hitting a wrench on the burner can?
Its part of the background music. Adds an interesting "touch" considering it really is a metal can its in.
ruclips.net/video/9ufhewVoJCo/видео.html&ab_channel=KevinMacleod-Topic
Aaah, you don’t say! I would never have thought out that myself.
I somehow expected a glow plug like a diesel or gas oven or prongs with a big continuous spark like a home heating oil burner.
Fun fact, the ignitor plug tips are coated with beryllium, which is extremely toxic. So wash your hands😊
Good to know!
Always wait for the required time after turningbthe system off, and pull the breaker. The amps the system throws out of the capacitor can and will kill you. Read the manual and observe!!
You could sell this as a Dyson barbecue or cooktop
Put kettle on, mother!
i can't imagine what it'll do to a car engine if you somehow manage to fit them
Lol is that Kerbal music.
Ha ha, Kerbal music. I have never played Kerbal. Just FYI. The music was supplied by RUclips.
That's what I thought too...
The first step is admitting you have a problem.
Cool