1QwkSport2.5r

Gasoline is lighter than methanol but not by much. Gasoline is .65g/mL whereas Methanol is .79g/mL. .14g/mL isn't much. 300cc gasoline is 195g and the same amount of methanol is 237g. 42g is what... 1.5oz give or take? Not a big enough argument for me.

drac1

My Feedback: (4)

I use 30% nitro in everything and being 20% heavier than methanol it would add up depending on the size tank. But the weight of fuel wouldn't be a deciding factor for me either.
Methanol engines with cdi is the way to go. Hopefully other manufacturers other than YS will go this way.

SrTelemaster150

If Saito would do that on their radials they would be awesome. 30% nitro W/CDI make crazy power too. 4HP in my modified FA180HC engine W/the big 12mm carburetor. That's .5HP better than the same combo W/15% nitro.

1QwkSport2.5r

There aren't a lot of folks running that high of nitro, most folks even at 15% nitro fuel is only about 10% heavier than gasoline; hardly still an argument. It really comes down to fuel economy that's the real savings generator and like most have said, adding in other costs and time associated with gas, it's ultimately preference. At least IMHO that is. If Walbro made an alky carb small enough for a 16cc engine, I'd convert all of my Walbros to methanol and use diluted glow fuel in my lawn equipment.

Luchnia

My Feedback: (21)

Most I know are converting to gas and electric. Glow will probably be minimized in time, especially as gas become more competitive priced. The smaller gas engines are super economical. I converted all of my planes out but two and plan on getting rid of one of those and only keeping my trainer as a glow plane. I might even change that out. Gas is so economical for me.

I was a strong glow advocate and very die-hard, however I have changed my tune now. After running gas for a couple years, I don't even bother looking at glow of any kind. I think it is only a matter of time that you will see mostly electric and gas at the fields.

SrTelemaster150

In what dream world will gas become "more competitive priced"?

For one thing, we need to end gas subsidies that depress gas prices to curb wasteful habits like pick-up trucks & SUV being used as daily transport in urban areas. I'm sick of my tax $$$ being used so that soccer moms in Atlanta can afford to drive 12MPG SUVs.

End the subsidies, put a $4 a gallon tax on non-commercial use of gasoline & eliminate income tax for anyone making less than $100K a year, $150K for couples. etc.

Not that gas R/C engines are a factor in wasteful gas usage, but gas is too cheap in the US. I am amazed at people filling up their short bed 4-door pick-ups (that never see a "load" in the beds) complaining about high gas prices. My 2006 dodge Charger could do the 1/4 mile in 12 second flat & get 26 MPG on the interstate, 28 MPG on rural hi-ways @ < 65 MPH cruising speeds.

Double the price of gas & the average fuel economy will triple & we can enjoy our internal combustion engines for 3X as long..

As far as LARGE GI (glow ignition) engines? Yes they are not practcal, but IMO if CDI/methanol engines would be offered in .91 sizes on up, many would opt for the much better power/weight output W/O the smelly & more dangerous gasoline.

YS has done it, when will saito follow suit?

Luchnia

My Feedback: (21)

Sorry about that. I meant that the gas engines should be more competitive priced. Gas is ridiculously priced and will probably not get better.

Sport_Pilot

The large gassers have more torque because they are bigger engines designed for lower RPM because you can only turn the larger prop so fast. If they were converted to glow or CDI methanol they would have even more torque.

Hobbsy

My Feedback: (102)

It's a shame we can't un-lump some of the larger engines and say they are more ecenomical than some of their peers. For example, starting with the SuperTigre 2300 the larger SuperTigres have pretty hefty prop recomendations and run well below 9,000 rpm. This leads to fairly frugal operation. Part of that equation is getting the carb set correctly, especially the LS needle. 0 to 5% fuel also helps.

Cobra1

My Feedback: (42)

None of you guys must play golf - it is expensive and it is a hobby. Flying my planes is a hobby as well and the price of glow fuel - even if i burn a gallon or two in a day at the field is still cheaper than golf where I live. I like gas in larger planes but I still fly my saito 180 on 20% - love the sound.

Sport_Pilot

For nitro you can just buy Plasticote acrylic laquer in a spray can and costs about the same.

Sport_Pilot

I hope this is not the next craze. 100% nitro blown engines going off like bombs at the field. Hopefully you cannot use 100% nitro because it would need more power from the ignition, or at least to run the super rich mixtures the drag racers use.

Sport_Pilot

Gas subsidies? I thought gas was heavily taxed not subsidized. Uncle Sam makes for more money on gas than the oil companies. Perhaps you mean the tax breaks givin to oil well investors? Well that helps exporation and we need more of that.

SrTelemaster150

Quote:

Originally Posted by Sport_Pilot

The large gassers have more torque because they are bigger engines designed for lower RPM because you can only turn the larger prop so fast. If they were converted to glow or CDI methanol they would have even more torque.

That's absolutely correct. I see guys drooling over the gas FG84 thinking it will have more TQ than the smaller but equally powerful FA450.

It probably does make more TQ @ a lower RPM than the FA450 but it isn't the "gas" that does that. it is the added displacement as you pointed out.

I've gathered almost all of the parts to make a DI/methanol version of the FG84. Using FA180 pots, the engine will have the same bore/stroke W/the added power potential of the bigger 180 valves & the case will be machined to reduce the compression height by 1mm boosting power even further by increasing CR, something that isn't practical W/gasoline as the stock CR is about maxed out for gasoline in an air cooled engine. i have had the back plate machined to accept the larger threads of the FA150/180 intake manifold & will experiment W/10mm, 11mm & 12mm glow fuel carburetors.

W/CDI/methanol I expect power output to be in the 7 1/2+ HP range W/15% nitro/methanol. I am hoping that the added TQ will swing a scale like 26X10 3-blade prop W/enough static RPM for good climb & unload @ speed for good scale like speed, about 80MPH in the 1/5 scale TopFlite FW190A. The cooler running methanol should allow loading the engine w/a big prop to take advantage of the increased TQ W/O overheating like a gasoline burner would.

It should also be quite economical @ part throttle cruise.

SrTelemaster150

The oil companies make billions in profits that should be used for exploration. The subsidies increase profits @ this point reducing gasoline prices to artificialy low levels.

That's why our rail transit industy is a joke compared to the rest of the developed world & our roads are clogged W/large ineffecient trucks that not only are unsafe due to increased roll-over potential, they in themselves make small cars more dangerous when they are impaceted by those 3 ton behemoths. Our roads would be safer W/O all those huge gas guzzling hulks. If you get hit by a semi, the SUV isn't going to save you. If 2 SUVs collide, the energy of the impact is increased exponentially so that doesn't help survivability either.

MJD

My Feedback: (1)

The stoichiometric ratios are based on mass, not volume. The density of the fuel isn't relevant with respect to fuel payload, only the mass of fuel.

The volumetric ratio of liquid glow fuel to air is in the thousands (thousands of cc of air to one cc of liquid fuel), as is gas:air. As an example, I worked out the air consumption of a ducted fan .65 to be in the order of 4+ litres per second.

jester_s1

I've been in the hobby 8 years now and am actually surprised at what I've seen in the development of power plants. I think I'm in the sweet spot for observing trends- been around long enough to see them but not so long to be set in my ways. When I started, glow dominated. Electric was for small planes or tech geeks who wanted to make it work for larger planes and were willing to accept the weight penalty. Gas was mostly converted chainsaw engines unless a modeler was willing to spend big bucks on the (then) new purpose built hobby gassers. I've watched electric improve to the point that power to weight ratios are actually better than wet power across the board. Gassers have also improved in the power they make and the ease of starting with electronic igntions, and they've gotten so much cheaper. Add to that the ease of tuning them and the reliability and it's a no brainer for the bigger planes. Glow dominated for so long because nothing else could match it for the power to weight ratio, but that's just not true anymore. How have glow engines improved during that same time? They haven't. Oh, some new models have been released because marketing demands it, but there have been no genuine innovations in glow power for a long time. I'd love to see a factory built pumped and CDI glow engine in maybe a .65 that matches the weight of the OS .65 AX. But it's not gonna happen because all the manufacturers are putting their R&D money into gas.
I think that truthfully, none of us really like using glow engines. The tuning is temperamental, they require fuel proof finishes, they spray slime all over the planes, and the fuel is expensive. We've learned to love them because they represent doing the hobby, but if we are honest even the good ones are a pain to fool with. Learning to tune a glow engine has been the roadblock that kept many a new modeler from successfully entering the hobby, and one could fill a warehouse with stacks of paper if every thread on the topic from RCU and RCG were printed out. The hobby wants more convenient power systems, and both gas and electric provide that. If the options we have today had existed in the 70's, glow probably wouldn't exist at all today. Looking forward, I think .25-.90 glow engines will stick around. Electric is more expensive at those sizes and gas is significantly heavier and more complicated with the separate ignition battery and can't turn the RPM's that glow can at that size. Electric will probably become competitive cost wise within another 10 years, but we airplane guys like the noise. So glow engines in those sizes will continue to be available, but anything outside of that will become very special purpose.

blw

My Feedback: (3)

This is just my opinion, which may not be the same as most people. Not trying to argue any point here, but for me I like tuning engines. To me, there's nothing better than hearing a perfectly tuned 4 stroke coming in to land, or hitting the throttle hard on a vertical. I don't mind the mess that much. I use a good wax on Ultracote to keep scuffs from showing, and it makes it pretty easy to clean.

I've got a few small electrics for indoor flying. I'm fortunate enough to work part of the year teaching college kids to fly r/c and I've bought about a dozen park flyers for that. Electric doesn't turn my crank. It just isn't as much fun. I've tried to make myself like it, but it ain't happening. I would be happy with 90 sized glow engines from now on. I could live with 60 or 90 sized models.

I'm building a 30 size Cloud Ranger for work over the holidays. The electric stuff for it is heavy and just as expensive as if it were glow. I look at the big brick battery and worry about fire. There's nothing to love. But that Saito 30 GK sitting on the shelf is a thing of beauty and I admit loving that engine. Plus, I can work on it if I want to.

Just my .02 cents. I would sure hate to see things get more lopsided towards electric.

Sport_Pilot

IMO gas needs to be cheaper not more expensive, but now we are delving into economics and politics and not on topic. So that is all I have to say about that.

FSki

The only thing stopping me for trying a gas engine at the moment is noise, whenever a 20-30cc gas engine turns up down the field it can't meet our field noise regs (82dba at 7m) on it's standard silencer, whereas the big glow fourstrokes don't seem to have a problem.

SrTelemaster150

In Saito's case, the R&D for CDI/Methanol is already done. Except for building in 8° more spark advance in their limited adjustment sensor arangement, all of the parts already exist. It would be plug & play


From a usage viewpoint, CDI/mehanol is just as convenient as gas & somewhat easier to tune. The added safety & lack of noxious fumes make up for the inconvenience of purchasing glow fuel

Gas won't make the same power as CDI/methanol in any high output engines of similar displacement/configuration. It just isn't possible.

SrTelemaster150

Yes we can agree to disagree on that. Though an interesting point is that some of the very same people that harp about $4 a gallon for gasoline will gladly go to the cooler @ the convenient mart & purchase a pint of bottled water for $1. That's 2X the price of gasoline.

GerKonig

Well, one thing is clear to me: They sell more and more gas engines of all sizes. A lot of people fly big electrics (like the 1.6 electrics which I use to replace Zenoahs and Quadras).

So, if there are no huge additions to the number on modellers, it would be safe to think that gas and electric are indeed taking over the part of the market glow propulsion had in the past.

Are they (gas and electric) killing glow? No, they just are resizing the market (less people are using glow)... Glow will never disappear, it just will be a smaller market.

Gerry

earlwb

Well if you look back at the past. In the early days it was rubber band powered and compressed air or CO2 types of motors. At first the compressed air motors ruled the skies and out performed the rubber band powered planes. The gasoline spark ignition engines came along and became quite popular even though the mechanical ignition points or breaker systems were prone to being unreliable. Then after World War Two, the model diesel engine came onto the scene and really put a dent into model gas engine sales. Model diesel engines had no points, no onboard batteries no spark plugs, etc, and were very reliable and developed good power as well. But the model diesel wound up being exclipsed by the model glow engines.

The glow engines used a glow plug and developed more power at higher RPMs and glow fuel was cheaper to make and more safe to store and sell too. The model gas engine almost died out entirely after the glow engines took off. Years later there was a demand from the modellers for larger more powerful engines to power giant scale planes, and the glow engines started getting more and more large in displacement to fill the need. But along the way the gas spark ignition engine came back onto the scene. But at first the gas engines were heavy and combersome and not all that great on power output, as the magneto ignition and heavy flywheels tended to impact performance a lot. Then came along the electronic ignition systems and suddenly the large gas engines became more light weight, more powerful and much easier to start too.

So technically we are only going full circle by embracing gas engines again. We used to have model gas engines years ago, so we are merely embracing it again. But none of the different systems used to power a model airplane have go away, they are still all there and we still use them all.

Heck there is a small niche for folks using model steam engines to power airplanes with too. They used to use steam engine powered planes way back in the 1800's even. I got to thinking that the modern liPo or LiFe battery packs could bring steam engines back to more popularity over time too. We could use a LiPo pack to power a heating coil to flash water into steam for driving a steam engine.
Thus no open flame and no fuel needs to be carried on the plane.

flycatch

My Feedback: (26)

History does have a way of repeating itself.