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Smallest gasoline engine?

Old 02-27-2006, 02:40 PM
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mazer
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Default Smallest gasoline engine?

What size plane do you start putting gasoline engines on? Do they make small ones? Other than the mess, what would be the plus to putting one on vs a glow engine?
Thanks!
Mazer
Old 02-27-2006, 02:43 PM
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Red B.
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Default RE: Smallest gasoline engine?

It all depends, but glow engines larger than 2.1 cu.in. are rare as are gas engines below 1.2 cu.in.

/Red B.
Old 02-27-2006, 02:56 PM
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mazer
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Default RE: Smallest gasoline engine?

Ah....it's for the big stuff only then!

So....when I see threads where folks are discussing what engine to put in, and one guys says "i'm putting in a Saito 1.80" and is followed up by the next guy "i'm going to put in a g23 or g26 instead", I have to wonder why? Is it like the difference between a 2 stroke and 4 stroke glow?
Or when you get to a certain size it becomes a personal choice? Or do aircraft models specify gas or glow at some point?
There is one fellow at the field I fly at that has a gas engine, it sounds like a chainsaw....seems to have lots of power though.
What about multi-cylinder engines...i've seen them online offering as many as 9 cylinders to a single engine!!!!!
Old 02-27-2006, 03:07 PM
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rjm1982
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Default RE: Smallest gasoline engine?

I havent played with gas yet, but i can see one of the draws. A gallon of glow fuel, 11-15 bux, gallon of gas, 2 bucks...hmm...
Old 02-27-2006, 03:13 PM
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Red B.
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Default RE: Smallest gasoline engine?

ORIGINAL: mazer

Ah....it's for the big stuff only then!

So....when I see threads where folks are discussing what engine to put in, and one guys says "i'm putting in a Saito 1.80" and is followed up by the next guy "i'm going to put in a g23 or g26 instead", I have to wonder why? Is it like the difference between a 2 stroke and 4 stroke glow?
Or when you get to a certain size it becomes a personal choice? Or do aircraft models specify gas or glow at some point?
There is one fellow at the field I fly at that has a gas engine, it sounds like a chainsaw....seems to have lots of power though.
What about multi-cylinder engines...i've seen them online offering as many as 9 cylinders to a single engine!!!!!
There is a transition zone between 1.2 and 2.1 cu.in where it's more or less a personal choice which type of engine to use.
Some multi-cylinder four stroke glow engines go well above 2.1 cu.in. The Saito FA-450R3D 4.5 cu.in. radial engine is one example.
Some kits designed for 1.2-1.8 cu.in. engines are to lightly built to withstand the pounding of low revving gas engines. Apart from that the choice is yours.

Be warned, some people tend to get quite religious about the pros and cons of gas and glow engines :-)

/Red B.
Old 02-27-2006, 03:23 PM
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Default RE: Smallest gasoline engine?

mazer,

allot depends on the plane but a 120 size is about the smallest for gas engines depending on the plane. Now others are putting the new Evolution 1.6 engines into 90 size planes, mainly the Showtime and now the Funtana90 and getting good results but thses planes have large wings and loads of wing area for their size.

As an example I own 2 Carl Goldberg Sukhoi's. One has a YS140 glow engine and the other a lightened G26 in it. Both weigh within 1/2 pound of each other but the G26 powered one required a lot of C/F to get it lighter. Why lighter, well wing loading is a big factor. The gas enigne is 20 ounces over what the glow engine is, so I had to put the gas engined version on a serious diet by replacing everything I could with Carbon Fiber, Li-Ion batteries and allot more

Now both fly very well and are about equal in power but the gas powered one requires me to land a little faster as the stall speed is higher due to the higher wing loading. Given the same size tank in each more. I get way more flight time on the gas engine than I do with the glow engine

Now on the other hand, Great Planes make a very nice Super Stearman that is built around the OS120 glow engine. In the manual for this plane they say you need approx. 18 ounces of nose weight just to balance it. So now you have an option:

Do you add 18 ounces of dead weight or do you go with a heavier more powerful engine. I went with a G26 which turned out to be exactly what I needed and so did several others. Wing loading was not an issue for this particular plane.

So you must ask yourself several things. Gas engines are heavier than glow engines, glow engines burn allot more fuel, gas engine burn considerably less fuel but you need a bigger gas engine to get the same power as you would with a much smaller and lighter glow engine. Remember weight and wingloading are everything. Lighter is alwys better.
Old 02-27-2006, 03:34 PM
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Default RE: Smallest gasoline engine?

BME Engines are not selling gas converted glow engines in the .90 size. It is a converted Super Tiger.

[link=http://bmeengine.com/html/point90.htm]http://bmeengine.com/html/point90.htm[/link]

I haven't tried one but it seems interesting!
Old 02-27-2006, 04:16 PM
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Default RE: Smallest gasoline engine?

As others have mentioned, there is a transition area around the 1 to 2 cubic inch area where glow engines fade out and gas engines start in.

Gas engines have extra “stuff” with them, such as batteries & ignition modules, or a magneto. This weight penalty is a lot on small displacement engines. However, as engines increase in size, the battery and ignition module weight becomes less significant as they represent a lower % of the total weight. Gas engines also tend to have much lower power to weight ratings.

Glow engines draw a lot of fuel. A ~1.5 cu.in. can draw around 3/oz a minute. A 6 cu.in. gas engine has about the same fuel draw. This is a triple whammy. Not only is glow fuel much more expensive than gas, but the glow engine is more hungry by a factor of about 5X or more… that’s the double whammy. The triple whammy part is that a 6 cu.in. glow engine may weight less than gas, but the required tank size and fuel weight for a 10 minute flight would be large, like a gallon or more, which actually makes the gas engine setup lighter and explains why there aren’t 6 cu.in. glow engines as you’d need to carry 10lbs of fuel for a 10 minute flight.

It is these factors combined, and I’m sure other factors, that explain the switch from glow to gas around the 1-2 cu in area. I am of the opinion that you are better off with glow until the high side of that transition, i.e. I’d use glow up to 2cu in, and wouldn’t go smaller than 40-50cc for gas. But there are some good running gas engines in the 25cc area (~1.5cu in). They are cheap to run, but they don’t have near the power of a similar sized glow and they tend to weight more.

Cheers
Old 02-28-2006, 08:20 AM
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mazer
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Default RE: Smallest gasoline engine?

Wow! Thanks for all the great information! It has definitely removed the mystery. As I move up in plane size I was wondering when to make the switch...now I have a much better understanding. Thanks for all the great information...I hope a few other of the novices out there got to read this thread...especially those that don't have a mentor(me being one of them) to lead them forward in this great hobby!
Mazer
Old 02-28-2006, 07:15 PM
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Default RE: Smallest gasoline engine?

Some people convert glow engines to spark ignition. This is possible with battery powered electronic ignition modules that use hall effect sensnors to trigger the spark. They even make spark plugs with 1/4x32 threads that fit right into glow plug holes. Large 4-stroke engines converted to spark will reliably idle at rediculously low rpm and need no nitro. While you can convert a .40 to spark, the extra weight of the ignition system is not worth it, and you will still need to feed the engine a fuel blend that is about 20% oil.
Old 03-01-2006, 08:48 AM
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Default RE: Smallest gasoline engine?

Thanks for that B.L.E., good to know there are even more options!
Old 03-01-2006, 11:10 AM
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Default RE: Smallest gasoline engine?


ORIGINAL: rjm1982

I havent played with gas yet, but i can see one of the draws. A gallon of glow fuel, 11-15 bux, gallon of gas, 2 bucks...hmm...
Good point ...however....lets say you are deciding between an OS 1.60FX ($260) and a Brison 2.4 ($520). For $260 you can buy around 17 gallons of fuel at about 12-14 twelve minute flights per gallon. Thats well over 200-225 flights or over 35 hours of flight time before you start saving money on gas.
Old 03-01-2006, 11:32 AM
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Default RE: Smallest gasoline engine?

ORIGINAL: mwarren400


ORIGINAL: rjm1982

I havent played with gas yet, but i can see one of the draws. A gallon of glow fuel, 11-15 bux, gallon of gas, 2 bucks...hmm...
Good point ...however....lets say you are deciding between an OS 1.60FX ($260) and a Brison 2.4 ($520). For $260 you can buy around 17 gallons of fuel at about 12-14 twelve minute flights per gallon. Thats well over 200-225 flights or over 35 hours of flight time before you start saving money on gas.
For those of us that spend more time at the field than work/home then 200+ flights per year is easy to obtain. My average is well over 400 per season and our season is basically mid/late March to late November/early december. For those of us that compete then in most cases your first 40+ flights are trim flights, then you get into practicing.

Now looking at the quoted numbers and assume you can fly all year round if you want to barring weather related stuff, lets say you fly 4 flights on Saturday and 4 flights on Sunday. You do this 40 times a year. So 8 times 40 equals 320 total flights (8 flights over the weekend and 40 weekends) and that is just on weekends and I used 40 as an arbitrary number assuming 2 weeks vacation and 10 weekends where weather/family issues keeps you grounded. This also assumes you only use 1 plane the whole time. I usually take 2 planes with me and fly both of them 4 times in a day so now that is 8 flights per day, 16 per weekend.

And I am not even adding in those late afternoon, summer evening flights throughout the week.

So all in all you will at least break even in the first year as well as save a little bit and then the savings really kick in on the second year, assuming the planes expiration date is at least two years.

As I said, I'm not the average hobby pilot. I love to fly and compete and I fly allot so for me gas is the way to go. Your mileage will definitely vary
Old 03-08-2006, 01:20 PM
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Red B.
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Default RE: Smallest gasoline engine?

Here is a brand new jewel: The .91 Webra 91-P5 Heli Ignition engine. Complete with pumped, regulated carb and electronic thyristor ignition.
Claimed power: 3 bhp (!).
Weight: 780 g = 27.5 oz. (presumably w.o. muffler)
Oil/Fuel: 1:20

Nice!

/Red B.

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Old 03-10-2006, 08:03 PM
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Default RE: Smallest gasoline engine?

I heard today,that evolution is making an .061 gas engine, havent done any reasearch on it though, so thats around 16cc.....Rog
Old 03-11-2006, 11:01 PM
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Default RE: Smallest gasoline engine?

It's not really an RC engine, but Shilen Aerosport has a .19 cu in ignition engine for gas-oil mix. There are a number of reproductions of older model airplane ignition engines available, possibly even smaller than .19, generally for use in SAM old timer competition, either for FF or for R/C endurance, timed engine run or fuel allotment.
Old 03-12-2006, 07:57 AM
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Default RE: Smallest gasoline engine?


ORIGINAL: flyinrog

I heard today,that evolution is making an .061 gas engine, havent done any reasearch on it though, so thats around 16cc.....Rog
opps sorry that would be 10cc,
Old 03-13-2006, 09:54 AM
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Default RE: Smallest gasoline engine?

Before Ray Arden invented the glo plug all model engines were gas, I still have two engines manufatured by Arden that are .09 and .19 cubic inches. The Ardens are the smallest I ever owned but also had an Olson .23 several McCoys, a Brown Jr. and others.

What the smallest manufactured now is I haven't a clue but know that weed wackers have been converted to model use and some of them are small.

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