As an owner/pilot, you're allowed to replace spark plugs. Here's a bit of knowledge about the two major types. Just a visual overview; this is not a maintenance guide.
Yeah; it took me a while to figure that out. For several flights, every other flight I'd have a failed mag check, and have to fiddle with spark plugs. I eventually realized it was the bottom of #2, and one time I took a very close look at it, and realized there was a tiny oil bridge way down on the electrodes. It was really hard to see.
There was a movement in the sixties to convince people in U.K. that the aircraft type spark plugs had been overtaken by a mixture of the massive a multiple fine wire type where the spark ran over the electrodes. This supposedly was because of failure upon take off of American Bombers at the late end of WWII. In U.K. aircraft plugs tended towards fine wire plugs in triplicate, I am told. A family member was, in this era the Factory Engineer of a spark plug factor. He has now passed on.
So by "fine wire plugs in triplicate", I presume that you mean that the plugs were different? Maybe they had three ground electrodes instead of two or one? Because while aviation engines do have two plugs per cylinder, both for redundancy and efficiency, adding a third would cause a huge amount of redesign to the engines.
@@fsodn Yes sorry I expressed it badly. They had three ground electrodes. There was also an American format where the spark ran over the face of a very broad electrode which I believe had three holes in it. It was supposed to improve take off performance of bomber squadrons which had accidents because of partly warmed engines. I remember reading the description as a Young man but never saw one. On the subject of spark plugs I note that nearly all garden two and four stroke engines are gapped to close and engine performance improves by gapping to 28 - 30 thou.
@@glynluff2595 If you have a very strong ignition source firing the plug, I believe you're right and larger gaps fire better. However, with stock magnetos, you have the keep the plug gap down to what the magneto and reliably fire across, or performance suffers for that reason. In the US, spark plug gaps for piston engines is specified by the manufacturer. I just looked up the chart for Continental engines, SIL 03-2B (my current airplane is a Cessna 150 with a Continental O-200-A engine in it). In that chart, the gap for Champion spark lugs is from .016 to .021 inches. If you swap one of the ignition sources to a hotter spark source, like one of the high-power electronic magneto replacements, I believe the STC allows a much larger gap on those plugs (but of course then you have to be very careful when rotating to keep the conventional magneto and electronic magneto plugs separate).
@@fsodn Ah yes and that is very true for your source. Here you are talking of an air vehicle which has limited liability of recurrence in difficulties. In wartime some repugnance of this is necessary to aid difficulties and in WWII air fuel really managed 100 octane despite suggestions. On land engines the octane was pool which was 68 for lorries and about 72 for standard motor engines. Today we look at 95 and 98 if you wish to pay for less addition to your fuel. The bio addition adds water carrying capacity to the fuel which reacts negatively if kept in fuel tank a long time. Therefore in a land machine it is often worth extending plug gaps a little because the extra heat of flame front will result in better combustion of gases. However, unburnt gas can with lower turbulence provide better burning of the next charge so performance can improve. There is only inconvenience today with land vehicles if there is failure but magnetos along with coil ignitions are as good as the people who set them up. In aircraft one will not vary from manufacture because of the insurance provision.
I don't know; I dont' have any real expertise in turbine engines, home-made or otherwise. I suspect, though, that turbine engines have their own ignitors that are different than the spark plugs used in reciprocating piston engines. I'm going to guess that a reciprocating spark plug, aircraft or car, wouldn't hold up very well at the temperatures in a turbine engine combustion chamber. I did a google search on "turbine engine ignitors" that looked like it brought up things that look vaguely like spark plugs, but sounded like they were used as ignitors in turbine engines, so that might be a place for you to start. Thanks for watching the video, and for the question! Feel free to check out other videos on my channel. I just got back into publishing the series on rebuilding the engine in my 1972 Volkswagen a couple of years ago.
Althou I don't have an aircraft, nor do any maintnance on any aircraft, this was a great video. :)
Fantastic! I'm glad you enjoyed it. I also have videos on working on my VW, so feel free to check those out as well.
Nice 👍
I own a 68' Mooney, that's currently being restored. Good to know about the oiling on the plug issue.
Yeah; it took me a while to figure that out. For several flights, every other flight I'd have a failed mag check, and have to fiddle with spark plugs. I eventually realized it was the bottom of #2, and one time I took a very close look at it, and realized there was a tiny oil bridge way down on the electrodes. It was really hard to see.
There was a movement in the sixties to convince people in U.K. that the aircraft type spark plugs had been overtaken by a mixture of the massive a multiple fine wire type where the spark ran over the electrodes. This supposedly was because of failure upon take off of American Bombers at the late end of WWII.
In U.K. aircraft plugs tended towards fine wire plugs in triplicate, I am told. A family member was, in this era the Factory Engineer of a spark plug factor. He has now passed on.
So by "fine wire plugs in triplicate", I presume that you mean that the plugs were different? Maybe they had three ground electrodes instead of two or one?
Because while aviation engines do have two plugs per cylinder, both for redundancy and efficiency, adding a third would cause a huge amount of redesign to the engines.
@@fsodn Yes sorry I expressed it badly. They had three ground electrodes. There was also an American format where the spark ran over the face of a very broad electrode which I believe had three holes in it. It was supposed to improve take off performance of bomber squadrons which had accidents because of partly warmed engines. I remember reading the description as a Young man but never saw one.
On the subject of spark plugs I note that nearly all garden two and four stroke engines are gapped to close and engine performance improves by gapping to 28 - 30 thou.
@@glynluff2595 If you have a very strong ignition source firing the plug, I believe you're right and larger gaps fire better.
However, with stock magnetos, you have the keep the plug gap down to what the magneto and reliably fire across, or performance suffers for that reason. In the US, spark plug gaps for piston engines is specified by the manufacturer. I just looked up the chart for Continental engines, SIL 03-2B (my current airplane is a Cessna 150 with a Continental O-200-A engine in it). In that chart, the gap for Champion spark lugs is from .016 to .021 inches.
If you swap one of the ignition sources to a hotter spark source, like one of the high-power electronic magneto replacements, I believe the STC allows a much larger gap on those plugs (but of course then you have to be very careful when rotating to keep the conventional magneto and electronic magneto plugs separate).
@@fsodn Ah yes and that is very true for your source. Here you are talking of an air vehicle which has limited liability of recurrence in difficulties. In wartime some repugnance of this is necessary to aid difficulties and in WWII air fuel really managed 100 octane despite suggestions. On land engines the octane was pool which was 68 for lorries and about 72 for standard motor engines. Today we look at 95 and 98 if you wish to pay for less addition to your fuel. The bio addition adds water carrying capacity to the fuel which reacts negatively if kept in fuel tank a long time. Therefore in a land machine it is often worth extending plug gaps a little because the extra heat of flame front will result in better combustion of gases. However, unburnt gas can with lower turbulence provide better burning of the next charge so performance can improve. There is only inconvenience today with land vehicles if there is failure but magnetos along with coil ignitions are as good as the people who set them up. In aircraft one will not vary from manufacture because of the insurance provision.
Could I use one of those to make a homemade jet engine or I could simply use regular car spark plug ?
I don't know; I dont' have any real expertise in turbine engines, home-made or otherwise.
I suspect, though, that turbine engines have their own ignitors that are different than the spark plugs used in reciprocating piston engines. I'm going to guess that a reciprocating spark plug, aircraft or car, wouldn't hold up very well at the temperatures in a turbine engine combustion chamber.
I did a google search on "turbine engine ignitors" that looked like it brought up things that look vaguely like spark plugs, but sounded like they were used as ignitors in turbine engines, so that might be a place for you to start.
Thanks for watching the video, and for the question! Feel free to check out other videos on my channel. I just got back into publishing the series on rebuilding the engine in my 1972 Volkswagen a couple of years ago.
@@fsodn thanks for the answer, it’s very nice of you !! I’ll sure check you’re other vids!