gas or glow
 

whats the advantage of gas engs.are they better than glow engs.what eqipment would u need for a gasser?im new to this so any help will be much thanks.

RE: gas or glow
 

LOOOOTTTSSS cheaper to run. Big glow engines will make you broke:) That's what I see as there main advantage. The sound is differant too, and you don't need a glow plug as they have onboard ignition systems.
-John

RE: gas or glow
 

It's also going to depend on how big you want to fly. The smallest gasoline engines are in the 20cc range, about the same as a 1.20 glow. If all you want is .40 or.60 size planes, not much choice except to go glow, but if you want 1/4 scale or larger, then gasoline is more economical.

RE: gas or glow
 

great so now i need a larger plane.that can be done.thanks guys.

RE: gas or glow
 

Zenoah G20ei just came out with a gas engine just for 60 size planes sold by Horizon.It's advertised in this months model airplane magazine.

RE: gas or glow
 

They had that motor on display at the Toledo show. Yes, it is a 60 size motor. But it's not going to fit in all 60 size planes. In the Horizon catalog they say it will go into a 60 size plane with a large round cowl, like some scale planes. After seeing the motor at the show I would tend to agree with them. Because of the carb on the motor it's not going to fit into all 60 size planes.

Just something to think about.

Ken

RE: gas or glow
 

Gas engines are PRIMARILY for BIG planes - 1.20 size (1/4 scale) and larger. While gas engines are cheaper to operate, the larger planes are noticeably more expensive and frequently require more expensive servos (among other things). Once you go over a 60 size plane, everything goes up in proportion to the size of the plane (sometimes not in proportion :D ). Engines are more expensive, larger, more powerful servos, etc.

RE: gas or glow
 

Hi all,

I read this thread about glow engines and gas engines, as glow engines have glow plugs, gas engines have spark plugs which I have seen being used in cars or in motorbikes, and gas engines are run by gasoline, am i right or wrong. I have seen higher displacement glow engines as well as lower, so are the gas engines. I have a question, that when the displacement or CC/CI inreases rpm decreases, the smaller the engine more the rpm. Does higher rpm make a difference in engine's performance, and can it take plane to a vertical climb up? or the gas engines with low rpms they have more power?. Why the rpm decreases when the size of engine increases?

Thanks

Mody

RE: gas or glow
 

On the other hand you need an ignition system and a spark plug. The ignition system needs to be shielded in order to avoid RF-intereference.

I would say that somewhere between 1.2 and 1.8 cu.in. the advantages of gas engines will outweigh the advantages of glow engines.
For small capacity engines (say below 1.2 cu.in.) there is not much to gain from going gas.

/Red B.

RE: gas or glow
 

Larger engines have lower RPM because of the inertia of the piston. I have a .061 that spins up to over 20K and a 2.2 gas that only tops out at about 8K. The piston in the .061 has alot less mass and a much smaller stroke. That means that there is less inertia to overcome and that the piston travels a much shorter distance for each revolution. As far as the performance goes, there is a trade off. Engines do make more power at higher RPMS, but the efficiency of the prop decreases if the tips of the blades go supersonic. Also, larger engines usually have more torque. This means that it can turn a larger prop with a greater pitch at lower RPMs to get the desired thrust. As far as vertical performance, that depends on the plane. Any plane will go vertical with enough power. Most large aerobatic planes have gas engines and unlimited vertical.

RE: gas or glow
 

Gas engines do have several advantages that make them very inviting to fly. In fact, because of the cost of fuel I am working to get more gas engines in my hanger and get rid of some of the glow power. But there are a few down sides that need to be considered when thinking about gas engines.
1. They are for larger models. As said above, 60 size is the smallest gasser out there right now. And even that won't fit all 60 size planes.
2. RFI. Gas engines can and do develop radio frequency interference (RFI). This can cause problems with your radio, so steps need to be taken to ensure that they don't interfere.
3. Vibration. Gassers tend to vibrate more than glow engines. Once again, not a huge problems but steps do need to be taken to keep them from causing airframe failure.
4. Fuel safety. Gasoline is a lot more volatile than glow fuel is. Safety steps need to be take in the storage, transportation, and handling of gasoline. At the very least you should purchase a fire extinguisher to keep in your vehicle and for use on the flight line. You also need to store gasoline away from any open flames or sparks. Glow fuel can't be ignited by a spark, but gasoline can and will explode if ignited by a spark.

Just giving you some things to think about. Moving to gassers can have a lot of advantages. As I said above, I'm starting to work towards getting more gassers in my hanger. Even though the price of gas has skyrocketed lately, even at $3/gallon it's still cheaper than glow fuel!!

Good luck

Ken

RE: gas or glow
 

Thanks Gravity,

I have understood very much about it now, thanks for your help. Main thing of engine is the more space which reduces more inertia, the more time engine would take to complete the cycle the more powerful it would be and more push it would give to the plane. Once again thanks

Mody

RE: gas or glow
 

i disagree TOTALLY with rcken. YES glow fuel can be ignited by a spark. even a static discharge will set it off.

i own a "gasser" that was giving me all sorts of problems......so converted it to run methanol. i did nothing more than make an adaptor to use a glow plug in the spark plug hole and retuned it. the engine is 45cc in an 84" extra 300.....works VERY well

cheers
craig

RE: gas or glow
 

In general, spark ignition is not practical in smaller engines (0.6 cubic inches and smaller). It can be done, in fact it was done in the 1940's before Mr. Arden invented the glow plug. The 1/4 x 32 glow plug thread size was originally the size of micro spark plugs used in these engines. The problem is that an ignition system for a small engine is just as heavy as one for a big engine.
Even though glow fuel is expensive, a .40 size engine does not burn much of it.

RE: gas or glow
 

bugger the cost of glow fuel. if you want more horsepower....run alcohol fuel. i am and i havent looked back. my engine now makes s@%&loads more than it ever did running petrol.

everyone craps on about "it costs too much to use methanol fuel"....for me it adds about $100 per year more than using petrol. plus i dont hafta have another container for a different fuel. all my fuel for all my aircraft now comes out of the same fuel drum....easy as.


cheers
craig

RE: gas or glow
 

hardtop: Nice job! What brand and no of glow plug works best? Thanks Capt,n

RE: gas or glow
 

Another big advantage of gasoline, you can use much smaller tanks in the plane, roughly a gasoline engine will only burn half as much per unit time than a glow engine will. While you can convert a gasoline engine to glow (as mentioned above) it does create problems when doing so. The biggest one is that you need to replace the carb in order to run glow fuel in a gasser (requires larger offices and fuel passages to accomodate the increase fuel consumption). As far as vibration goes, the big glow engines vibrate as much as the gasoline engines do although the glow engine will be lighter than the gasoline engine for the same cc and will put out more power per pound of weight, just use a lot more fuel.

RE: gas or glow
 

You sure the glow will be lighter... Take into account how much extra fuel is needed thats the big thign if you add lets say 20 oz of extra fuel could easly add a pound to the plane and i highly dought your removing a pound.

For small gas engines has anyon taken a look at the small bme .90 .

RE: gas or glow
 

I second that!! In fact, glow fuel works just fine in spark ignition engines. if the carburettor is designed to meter glow fuel, it needs to be richer than gasoline.
Glow fuel however does have a higher flash point than gasoline does and so gasoline is a lot more hazardous than glow fuel. Gasoline will provide flamable vapors in temperatures as low a minus 40 degrees F. Methanol has a flash point of around 50 degrees F. At temperatures lower than that, it does not provide enough vapors to form a combustible mixture. That's why you see people prime full scale methanol burning race cars with gasoline before trying to start them. It's also why they sell E-85 instead of E-100 at the gas station. That 15 percent gasoline is there so engines will still start in cool weather.

Another advantage of gas models that no one has mentioned yet is that gas powered planes don't get as messy from exhaust residue. Most gas engines have needle bearings in the con rod and can run with fuel that's around 2% oil. Most glow fuel is around 18% oil and it mostly ends up on the plane's fusilage after it goes through the engine.