2W0EPI

Engine manufactures don't seem to provide gas engines below about 10cc or .5cu.in, unfortunately, the most popular and lowest cost entry level rc plane size is around .46 cu.in with a suitable aptly sized plane.
As one moves beyond .5cu.in in an increasing manner, prices/costs go through the ceiling.

kmeyers

I posted this awhile back:

under 4 lbs: electric.
over 8 lbs: gas
4 - 8 lbs glow might work under review of needs and use.
36" wingspan gillows, no question at all today.....electric!

4 -8 lbs electric is an option too. Gas can go as low as 5 lbs with the right plane.

So my thinking is the market place knows what is selling, current gas sales under 10cc is not where consumers are.
There is a great thread on this site where guys are using pumps,radio programing, and electronics to convert old small glows to gasoline with great results.

Quite frankly, your g*******t is the reason for import costs making entry level costs high. I recently bought a RTF package on Amazon to fly with my grandkids (AEROSTAR, dxe, 3s 2200mah). 175 dollars and 30 minutes later the plane was in the air.

This is simply the best time in history for our hobby here in the USA. I don't know why the hobby is not growing.

I think a 9 -10 cc engine can work in an entry level .46 cu trainer easy. Use a BEC with a small tank and you have a monster with long flight times.

Good luck, and some feed back on this post would be helpful.

2W0EPI

I was hoping you would tell me why gas cuts off at 10cc?, is it a technical or engineering problem? I notice OS launched ggt series 10cc and 15cc which use gas but work like glo, although I am not sure, the 10cc version has been discontinued?

Why can't engine manufactures introduce .46cu.in gas 2 stroke?

Outrider6

My Feedback: (2)

This bugs me too. I was sorely disappointed to see the Saito .30 go away. There are a few kits I would like to build, but the lack of engine choices easily available are a huge controlling factor in that. For example, I would LOVE to build a Uravitch OV-10 for two Saito .30's, and a small Sig Kobra for a Saito .30 (or even a .20-.32 2-stroke glow, which are also difficult to find). I want front ball bearings and good (fully adjustable) carburetor on any of my engines, so the budget version of most engines, that are available, just don't cut it for me (anyone remember the OS .40 FP?). One of my old favorites, the Thunder Tiger Pro .46, can still be found as new-old-stock on ebay, but those will fizzle away until only used ones can be found.

Thing is, there is a demand for items such as this. I think enough demand to keep or revive old production, but not enough demand to start new production.

It takes smart business people to keep this part of the hobby alive. The monstrosity that got a hold of it a while back has never been too smart about doing much of anything, and I think they share a large part in carrying the blame for the decline of this hobby.

2W0EPI

Ah, I think I get it, if a particular manufacture introduced a good .46cu.in 2 stroke gas engine. then what would happen to the majority of the glo market? It would collapse right?

1967brutus

It is neither, it is a "political" problem. Not politics in the sense of left or right, tories or labour or such, but "policies" as in sales policies and strategies.

What is needed to make a small gasser run properly is not even all that expensive: my complete conversions come down to less than 150 pounds per engine, and that is homemade,and therefore relatively cost-ineffective. If a manufacturer would have to offer a package and the volumes would be there, they could do what I do for way less than 75 pounds per set I'm sure. That in itself should not be a problem: If people are willing to pay 100 pounds more just because it is an OS (which does NOT earn itself back, it's just a name, a reputation, a "feeling") for example, then they sure should be willing to pay for the fact that it is a gasser, because THAT is a thing that WILL earn back its additional investment, and rather quick I can say, even in these small sizes.
BUT: what I did is more or less 100% relying on the transmitter used, and the tuning skills of the end-user. That makes a product "unsellable", because half of the market, people that use different radios, won't be able to use it, and the other half has trouble getting it dialled in.

That problem can be circumnavigated by developing electronic control units that are specific to the engine, but THAT is a horribly expensive option, because it not only adds to the technical complexity (certain "user determined" variables need to be taken out of the equation by including the fuel supply system in the set-up) but also takes many manhours of testing to
get the fuel mapping just right, which in turn requires additional sensors to compensate for local variations in fuel quality etc etc.

And then all this work, labour and investment for something that is not patentable, because things like carburation, ignition, fuel injection and the likes are by now all part of "common technical knowledge, so a manufacturer cannot protect its investment against copying.
It is a hopeless situation and no manufacturer is going to want to burn its fingers on it.

Carburation is out of the question, because reality seems to indicate that simple carburation hits a limit WRT accuracy when engine size gets smaller than 15 or 10 cc (.9 or 06 cu.in.)

Technically, running small gas is absolutely possible, because if I can do it with basically zero means and capabilities, so can a manufacturer with decent R&D capacity. Commercially, there is no future in it however.
Sometimes I wonder what would have happened, if model engine manufacturers would have managed to develop small gasser engines 30 years earlier. My guess is that the reduction in slime and mess, the ridiculously low operating costs, and the ease of operation would have significantly slowed down the rise of electrics in the hobby.

Practically, it absolutely IS feasible, but that feasibility is conditional: It is an either/or thing. Stick to glow or go gas all the way. Because only one plane on gas does not save anything. It's not less hassle, it is not cheaper, it is not more convenient, one still needs to buy glow fuel for the remaining planes, still needs the paraphernalia for them. It only ADDS to the hassle.
Gas all the way, and suddenly things start to make sense (I do not run gasoline because I like tiny sparkplugs so much, I run gasoline because it is cheaper, cleaner and easier to use. I run gas in all my planes because of practicality).
But no manufacturer can bank on people doing that, because people by nature are "conservative" (NOT the political kind, the practical kind).

If you want to run gasoline, you've got to do it yourself. If you go gasoline, go all the way. If so, then it is absolutely 100% practical down to what traditionally would have been the territory of the .20~.25 class baffle piston glow engine.

1967brutus

are you kidding? Have you looked around lately? The glow market HAS allready collapsed... It collapsed with the introduction of LiPo and brushless motors. For the same weight of a .46 set-up (engine, muffler or tuned pipe and tank, and don't forget to take the additional weight required to strengthen the plane to withstand the vibrations AND the use of an electric starter into account) you can easily think of an electric set-up that leaves that .46 standing in its dust, performance wise. Gas is even worse in that respect to be totally honest.

2W0EPI

Why then is it still possible to buy 2 stroke glo .46cu.in engines at least by two manufactures? They should have gone bust years ago, not only are they still in existence but their prices are increasing as well by 10~20%?


The majority of models on offer (.46 size) offer both nitro and electric powered combined in the same kit, at no additional cost to the buyer.

Here we go again, a simple power calculation, in my head suggest electric powered is operating at its very limits, whilst aero glo's are looking for a parking place, a .46 glo can produce at least 1kW, that would require an esc of at least 100 amp and that's assuming it's 100% efficient which it isn't.

Well, that's the purpose of this thread, I want to buy a .46 cu.in 2 stroke gas because gas is much cheaper.

1967brutus

two decades ago you could buy them from at least 10 if not 20 brands. Is that an answer you can understand?

Is there a point you are trying to make there? Kit manufacturers are not engine manufacturers, they are trying to sell planes to people that might or might not have a .46 laying around. They are NOT trying to sell engines.
Well, If you're going again, while you're at it make a detour to review your data (because it is wrong), then go back to school to review your power calculations (because you don't seem to understand the implications). Have you ever heard of "P=U x I"? That formula means that if voltage rises, Amps drop for the same power.
A .46 in real life does about 800 to 900 Watt if you have a VERY good one, know how to tune and how to optimize your prop selection. If you don't (and I know you don't, because of the questions you ask) you're lucky if you will see 700 Watt.
An electric set-up running a 6S LiPo and with a total system efficiency of around 85% (which is easily achievable) does 1 kW at the shaft easily at slightly over 53 Amps, which absolutely is not an exceptionally high value. At 10S (also not an unusual voltage) it will do that power at a leisurely 31 Amps or so.
What is more: it will do that without any tuning skills of the user, and the output is relatively very easy to measure and determine. Does not take more than an A-meter...

I have noticed that you seem to always challenge information given to you here in these forums. And when you do, you do so based on very flawed arguments. Why is it so hard for you to accept even the simplest of truths? I mean, I am NOT trying to misinform you or anything. What would be the gain for me?
Whether you believe it or not, whether you like it or not, whether you wish for wet fuel to be more performant or not, electrics don't care about that, they strictly follow the laws of physics and consequently, because thise laws are what they are, will EASILY outperform wet fuel, by a margin of about 50% for the same take off weight, no problem at all. It is not even all that expensive to buy such a set-up. With a fair bit of certainty, if shopping at HobbyKing or the likes such a set-up is cheaper than an equivalent OS: My estimate is that a set-up equivalent to a 46 in performance (800W) will set you back less than 200 pounds, motor, ESC and batterypack.
Well, you can't... EVO engines had an 8 cc gasser, mixed experiences reported, ONLY availlable as part of an ARF kit, and Norvel had (or perhaps still has) a .40 glow gasser, with even more mixed reviews. You can try to get one of those, but they are either discontinued, or difficult to get, and your chances of success are marginal.
You can, however, modify an existing glow engine to run gas. Not sure if you will be successful at that, given your tendency to question everything and ignore straight facts and solid information.

It IS possible, here's my OS FXi46, it took quite a while of experimenting and messing about to get to this level:
That engine to date still has analog carburation. Plane and engine, although I do not own it anymore, still exist and are in use in my club. It has seen an awful lot of use.
This is another clubmate of mine, same engine (OS Xi46) but with the digital carb:
Looks good, runs perfect, has flawless carburation, but despite all that, electrics run circles around it.

2W0EPI

Well, so what. they are still available to buy at reasonable cost.

I would assume the buyer would have decided to choose the power plant before purchase of the kit, the main point is no specialist anti vibration equipment are required if fitting/choosing a .46 glow engine.


Well, of the top of my head it's in the ball park of 1kW, give or take.
In my original previous post I averaged at 3s lipo,(11.1V) you are boasting 6s lipo which is 22.V so the Amps drop in half from 100 to 50Amps.
Those batteries 6s lipo @5Ah are costing £110 each and a ball park calculation gives it about 10 minutes flying time.
I can buy an OS 46AXii for £120 that's £80 less than your electric setup and the electric will be running on its limit.
Because these electric power systems run at high currents it has since come to my attention that a lot these electrical systems suffer technical problems.

LLRCFlyer

I was raised on glow engines. I still have and enjoy flying glow engines. However, the economics of scale are responsible for the demise of glow engines. Too many people are choosing electric power and there is no longer sufficient demand for the .46 glow engines to support continued production at a profit. Glow fuel is expensive and the consumption rate for larger glow engines makes them cost prohibitive. The smaller glow engines are more affordable to run, but can be more cantankerous. The power-reliability-economy sweet spot for sport glow 2-cycle engines seems to be around .40 to .46. A 2 cycle gasoline engine will not produce as much power as an equal displacement 2-cycle glow engine. It would take a 9cc or 10cc gasser to make the same power as a 7.6cc (.46) glow engine. Although gasoline has a higher specific BTU content than methanol glow fuel, the ability to get the fuel and air mass flow into the combustion chamber and ignite it at higher rpm is better with a glow engine. You will see .46 glow engines routinely turning 13,000 to 17,000 rpm. You will likely never see that with stock gasoline engines. Very few gasoline engines operate well much above 10,000-12,000rpm. As a general rule of thumb, choose a gas engine of the same displacement as the recommended 4-Cycle glow counterpart. For example, if the kit calls for a strong 1.20 4-cycle glow engine (20cc), then choose a 20cc gas 2 stroke engine instead. My old 35 year old Enya R-1.20 4-cycle weighs within an ounce of my RCGF Stinger 20CC RE including its ignition system. They both turn 16 inch props and the Stinger has the power advantage. The additional weight of the electronic ignition and battery package is the same whether it be for a large single cylinder gasser or a small glow conversion to gas. The ignition weight penalty for small glow to gas conversions is a much higher percentage for the total power package weight. This weight disadvantage for small gas engines gives the advantage to an electric setup. Several of my flying buddies have gotten rid of all their glow engines in favor of electric motors for smaller models and gasoline engines for their larger models.

Glow engines smaller than .40 size have virtually disappeared because the electric alternatives just have too many advantages over smaller glow engines. The electric motors are extremely reliable, easy to operate, weigh about the same or less than their glow counterparts, are much quieter, turn thinner more efficient propellers, turn in 7 to 10 minute flights and use relatively cheap batteries that can be quickly recharged. Additionally, there is essentially no post flight cleaning required. As much as I love glow engines, I am afraid they (and diesels too) are becoming extinct. I guess we will have to learn to live with electric and gas engines and just retain fond memories of the "good old days" when glow was king and the smell of burnt nitromethane and castor oil was the ultimate perfume.

1967brutus

You ignore facts as you please....
You drag in unrelated and non-relevant facts at will...
You set your own accuracy standards at will
You move goalposts around and use skewed, non practical examples to try and make a non-existent point
now you also resort to not before mentioned conditions, but I can play that game too: I was assuming 3 Ah, and those cost 60 pounds and can ALSO give 10 minutes flying time if the pilot knows how to manage his throttle.
now you drag in discount prices which is unfair discussing technique: recommended retail for a 46 OS is 150+, but you need prop, tank, spinner and small stuff which WILL bring the set-up to 200 pounds
and now you are resorting to straight BS. That is not even remotely true, and you know it

Sorry dude, but you just have proven that you are NOT here to "discuss"... you are here to lure people into discussions then you try to derail them into arguments by introducing nonsense and non-arguments.
Hate to say it, but that is troll behaviour, and you're on my ignore list from now. People have warned for you, and I should have listened.
Not gonna make that mistake anymore.

Bye

1967brutus

About as true as it gets. And indeed, in order to replace glow for equivalent gas, you need a bigger engine... No big deal, so far I have always been able to cram in that larger engine or been able to live with the power loss...

As an additional: If the power-type (whether that is gas, glow or electrics) is being taken into account from the early design and construction stages of the airframe, differences can be even much larger. There's a huge difference between retrofitting and purpose-designing.

2W0EPI

If the OS 46 axii is too expensive, you can always go for the Force 46 which retails at around £100,

See here, non discounted OS 46axii for £120...

https://www.modelshopleeds.co.uk/cat...ducts_id=14267