3 ms·

glow plugs are pretty easy to start - stupid question, but you did have a big battery to power the plug?

dieselgate 4y ago
from the article it seems it's not a true "glow plug" heating element like one may use to start a diesel engine. my impression was the engine is so small the radiant heat of the engine is what causes the fuel to ignite in the chamber - seems tough to start cold
- zabzonk 4y ago
  diesels don't have a glow plug. a glow plug has a radiant coil that ignites the fuel, and then the heat of the engine keeps it firing, which is different from diesel fuel.a diesel engine depends on heating the fuel via compression with the energy being provided by the human flicking it. there is no battery input to a model aero diesel engine. a car diesel engine uses a starter motor to provide the initial compression.
  - stonogo 4y ago
    Just about every single automotive diesel engine sold since the 1950s is equipped with glow plugs, so the above post might be confusing. Automotive diesel glow plugs do not ignite the fuel; they lower the required compression in cold weather by warming up the air going into the combustion chamber. They're not the same things as glow plugs found in methanol-fueled model engines, which also do not ignite the fuel directly, but serve as a catalyst so the methanol can combust via compression instead of electric ignition. When talking about glow plugs, it's important to specity the sort you're talking about and the context in which your discussion is taking place.
    - zabzonk 4y ago
      i admit i am not an expert on modern auto diesels (i remember my brother muttering about having problems with this on his Merc). but 1960's model diesel engines did not require a battery to start them.
      - stonogo 4y ago
        Mercedes diesels were push-startable well into the 1980s. They still had glowplugs (even in the 60s) and if you did have a battery they would heat up the precombustion chamber to lighten the load on the starter motor.
zh3 4y ago
Yes, it was a big dry cell - there's a wire in the cylinder that glows orangey-red when powered (it was easy to unscrew the cylinder head to inspect the 'glowplug'.
greenbit 4y ago
The "glow plug" was kind of shaped like a spark plug, but instead of a gap for high voltage arcs, it had a small loop of platinum wire. To start the engine, you had to pre-heat the plug. This entailed attaching a battery, clipping one terminal to the top of the glow plug and the other to the engine, to send a current through the platinum wire. You'd use a 'D' cell, or maybe one of those big old No.6 types. A mere 1.5V, but you needed enough current to heat that platinum wire. This electrical apparatus had to be disconnected from the engine before you could fly the plane. Not sure if you could detach it before starting or not. That little wisp of wire would cool pretty darned fast with the current removed. I know with the larger RC planes the practice was to leave the glow plug heater attached until after the engine had started. Anyway, once the fuel mixture hits that hot wire, there's this catalytic reaction where the fuel at the platinum surface burns extra hot. This imparts enough heat to the glow plug wire to keep it hot enough for the next stroke. Idk what magic keeps the fuel from detonating before the piston reaches top of stroke, but I can attest these engines are fussy little things. They didn't idle very well; throttle them down too much and they just conk out. You can see other examples of this catalyzed combustion, and get a sense for what goes on inside the glow engine. These butane cigarette lighters that burn blue have a little bit of catalytic wire in them, you can often just see it glowing white hot just inside the flame opening. There also used to be these propane powered space heaters that had a gauze mesh of the stuff to boost the combustion efficiency.
- jacquesm 4y ago
  Disconnect after it runs, definitely. They'd cool down way too fast.

from the article it seems it's not a true "glow plug" heating element like one may use to start a diesel engine. my impression was the engine is so small the radiant heat of the engine is what causes the fuel to ignite in the chamber - seems tough to start cold

zabzonk 4y ago
diesels don't have a glow plug. a glow plug has a radiant coil that ignites the fuel, and then the heat of the engine keeps it firing, which is different from diesel fuel.a diesel engine depends on heating the fuel via compression with the energy being provided by the human flicking it. there is no battery input to a model aero diesel engine. a car diesel engine uses a starter motor to provide the initial compression.
- stonogo 4y ago
  Just about every single automotive diesel engine sold since the 1950s is equipped with glow plugs, so the above post might be confusing. Automotive diesel glow plugs do not ignite the fuel; they lower the required compression in cold weather by warming up the air going into the combustion chamber. They're not the same things as glow plugs found in methanol-fueled model engines, which also do not ignite the fuel directly, but serve as a catalyst so the methanol can combust via compression instead of electric ignition. When talking about glow plugs, it's important to specity the sort you're talking about and the context in which your discussion is taking place.
  - zabzonk 4y ago
    i admit i am not an expert on modern auto diesels (i remember my brother muttering about having problems with this on his Merc). but 1960's model diesel engines did not require a battery to start them.
    - stonogo 4y ago
      Mercedes diesels were push-startable well into the 1980s. They still had glowplugs (even in the 60s) and if you did have a battery they would heat up the precombustion chamber to lighten the load on the starter motor.

zh3 4y ago

Yes, it was a big dry cell - there's a wire in the cylinder that glows orangey-red when powered (it was easy to unscrew the cylinder head to inspect the 'glowplug'.

greenbit 4y ago

The "glow plug" was kind of shaped like a spark plug, but instead of a gap for high voltage arcs, it had a small loop of platinum wire. To start the engine, you had to pre-heat the plug. This entailed attaching a battery, clipping one terminal to the top of the glow plug and the other to the engine, to send a current through the platinum wire. You'd use a 'D' cell, or maybe one of those big old No.6 types. A mere 1.5V, but you needed enough current to heat that platinum wire. This electrical apparatus had to be disconnected from the engine before you could fly the plane. Not sure if you could detach it before starting or not. That little wisp of wire would cool pretty darned fast with the current removed. I know with the larger RC planes the practice was to leave the glow plug heater attached until after the engine had started. Anyway, once the fuel mixture hits that hot wire, there's this catalytic reaction where the fuel at the platinum surface burns extra hot. This imparts enough heat to the glow plug wire to keep it hot enough for the next stroke. Idk what magic keeps the fuel from detonating before the piston reaches top of stroke, but I can attest these engines are fussy little things. They didn't idle very well; throttle them down too much and they just conk out. You can see other examples of this catalyzed combustion, and get a sense for what goes on inside the glow engine. These butane cigarette lighters that burn blue have a little bit of catalytic wire in them, you can often just see it glowing white hot just inside the flame opening. There also used to be these propane powered space heaters that had a gauze mesh of the stuff to boost the combustion efficiency.

jacquesm 4y ago
Disconnect after it runs, definitely. They'd cool down way too fast.