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glow 4 stroke versus gas

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Old 08-03-2010, 10:07 AM
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dewald3@yahoo.com
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Default glow 4 stroke versus gas



I am new to hobby and so far have only purchased 7c futaba radio I plan on purcashing aarf trainer hobbistar 60 MK111. Since I have not puchased the engine yet should I go with the 4 stroke OS 91 pump or a gas engine ? If gas what make and size??? All help is appreciated
Don.

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Old 08-03-2010, 11:35 AM
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Default RE: glow 4 stroke versus gas

That's on the small end of gasoline engines. A Zenoah 20cc gas engine will be way more than you need for a .60 size trainer and is about the equivalent of a .90 2-stroke. RCGF, I think it is, has a 15 or 16cc that would be better size-wise but I don't know anything about one and have never seen one.
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Old 08-03-2010, 11:53 AM
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Default RE: glow 4 stroke versus gas

Don:

Welcome to the wonderful world of RC flying.

Since you're new to this hobby, one thing I'd consider is the group of people you're flying with. You'll probably find a majority fly 2stroke and 4stroke motors, and a smaller fraction operate gas motors. So there's probably more help available for the nitro variety at your field.

Another factor in the decision is probably money. While a gas motor is cheaper to operate, they're more expensive (based on list cost comparisons). A small gasser is also heavier than the glow equivalents, which could lead to a balance and/or weight problem on the trainer. So I guess my not so subtle recommendation would be towards the nitro powered motor.

There are lots of choices in the 90 4s size: OS and Saito tend to generate the most positive reviews, at the disadvantage of being the most expensive. Magnum, ASP (same as Magnum) and ThunderTiger also make 4S in this size, they're a bit cheaper and you'll find much more of the "love 'em/hate 'em" discussions with the lesser known brands. (I've got a Magnum 90 4s that runs like a champ.)

So to directly answer your question, I'd opt for the OS91, if that's the either/or choice for power. If you're open to other options, then I'd do some price comparisons with the other 4s models, and even consider a 60 sized 2s motor: they're less expensive, simpler to operate, and your 60 sized ARF is designed for one of them, so you don't get into ground clearance problems with the bigger props a 4s will turn.

Hope this helps
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Old 08-03-2010, 12:21 PM
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Default RE: glow 4 stroke versus gas

After I go from about 1.20 four stroke size I go into gas. I still have a nice 1.40 RCS gasser but after that you start looking at engines like the DLE30 or CRRC 26 then go up from there. I haven't used or seen any of the new small gas engines but if you want you can go into the gas engine forum and see what people that are really using them have to say, I have read reviews but I take those with a grain of salt. The OS pumpers are always a good choice because down the road they can be used in any 60 size plane with more then enough power. The pump allows you to mount the tank pretty much anyplace you like. I mount mine over the CG if I can. The OS four strokes are outstanding engines with or without a pump. When I can I always go for the pumpers.
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Old 08-03-2010, 12:57 PM
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Default RE: glow 4 stroke versus gas

Have you contacted the local club you'll be flying at? It would be a very wise idea to talk to their instructor. Depending on the size of the club, they may have one or several.
There are a couple of rules of thumb that apply here. Lighter flies better, and when you're starting out simple always beats complex.
If you apply both of those to your question, the answer is that neither of your choices is ideal.
Gasoline engines don't put out as much power as glow at that size, so you end up with a heavier engine for a given level of power. The ARF you're looking at wasn't designed with a heavy engine of any type in mind. What that means is that if you choose an engine that is heavier than those in the suggested range, you'll have to add weight to the tail in order to properly balance the model. More weight means that the plane has to fly faster in order to generate more lift. For a trainer, that's the opposite of what you want. You want something that can fly slower. That doesn't mean it can't fly as fast, it just means that everything must be done at higher speeds than if the model were lighter. When you're learning, that can mean the difference between a nice landing and a pile of sticks that fell short of the runway.
For both gasoline engines and 4-strokes, a larger diameter prop is ideal as opposed to the shorter props that would be used with a 2-stroke glow engine. You're looking at a tricycle gear trainer, so you'll want to make sure that the ideal prop for whatever engine you choose leaves you with sufficient ground clearance. If you're flying off of grass that can exasperate the problem of a larger prop. Depends on how much you like your model covered with grass clippings.
Simple really is better when you're learning. There's nothing complicated about running a 4-stroke, but if you choose to run a pumped engine you've added complication. It's an additional adjustment. Until you learn to run an engine, you'll make a lot of mistakes adjusting engines. There's a temptation to over-think problems and fiddle with things that shouldn't be fiddled with. Believe me, everyone does that when learning. Something less to fiddle with is a good thing. You'll already have more than enough to make mistakes with on a non-pumped engine. You want to spend your time flying, not being the guy in the pits scratching his head and trying to undo a series of well-intended but counter-productive adjustments. Pumps and pressurized fuel systems are great when they're needed. When they're not needed they don't do a thing for you. They're not needed with a trainer.
Gasoline requires an additional battery for the ignition system. You'll have enough to learn about batteries and power systems without having two batteries in the same airframe to maintain. It's two opportunities for error vs. one opportunity for error.
If you talk to whomever will be instructing you, they'll tell you what they're comfortable running. Some very, very good instructors don't use anything other than 2-stroke glow engines. If yours is one of them, gasoline or a pumped 4-stroke may put them outside of their own comfort level.
2-stroke glow or a non-pumped 4-stroke are both ideal choices for what you're about to learn to do. I know that's probably not what you want to hear.
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Old 08-03-2010, 02:28 PM
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Default RE: glow 4 stroke versus gas

Hi!
As a newbie a much better choice of engine would be a .40 two stroke!!
Forget about a large .91 four stroke if you are new to this hobby/sport, and definitely do not even think of a big gasser![>:]
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Old 08-03-2010, 03:24 PM
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Default RE: glow 4 stroke versus gas

Thanks for all the answers. The trainers at the club I am joining recommended either the 2 or 4 stroke I was leaning towards the 4 stroke but will get the 2 stroke instead.

Thanks again
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Old 08-03-2010, 03:28 PM
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Default RE: glow 4 stroke versus gas

I concur with sticking with a good 2-stroke at first. Simple operation, lighter than 4-stroke, all the power you'll need for your trainer. Biggest plus of all is far, far cheaper than a good 4-stroke engine. For example, you can get an OS .65LA for around $130, where the OS FS-91 Surpass II goes for $320, the Saito .91 for $310, and the Magnum .91 for $200 and up.

Get a decent 2-stroke glow engine for now. Once you've been flying a bit and have advanced beyond your trainer you can invest in a good 4-stroke engine. Smaller, more affordable gas engines are becoming available as well, but are really still in their infancy. I'm keeping an eye on them myself, but for now I'm sticking to glow.
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Old 08-03-2010, 04:44 PM
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Default RE: glow 4 stroke versus gas

The OPs question was between a OS .91 pumper or gas. A two stroke is much easier but wasn't put down as a choice. I do wonder what the difference is between tuning a four stroke pumper is compared to any other glow engine. I have seen that stated before and a pumper is the easiest of all glow engines to set up and tune. Other then valves that need adjusting every year or two what is the difference?? A high end needle and a low end needle. The fuel tank is vented instead of requiring a pressure line to the tank.
An inquiring mind wants to know??
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Old 08-03-2010, 07:46 PM
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Default RE: glow 4 stroke versus gas

The Hobbistar 60 was intended for a 2 stroke glow engine

It is an extremely nice flying plane with a 60 size two stroke

With anything else, there is going to be a nose heavy problem

Even the four stroke glow will present a problem because it will have to be mounted more forward on a new plastic mount to allow room for the carb on the back of the four stroke.

The plastic type motor mount will make it lighter in the nose. The Hobbistar I enjoyed for about 6 years had a aluminum motor mount from the factory. It balanced very well with the two stroke MDS 68 engine I had on it.
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Old 08-03-2010, 07:49 PM
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Default RE: glow 4 stroke versus gas

There's a new JBA 90 two stroke gas engine that has a layout much like a 60 glow engine with a Walbro carb up front. The engine is in stock at Valley View RC for $199 I think

This would be the closest gas engine that may possibly work in a Hobbistar
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