1967brutus

Hi all,

Just a short introduction: My name is Bert, I am a marine engineer by profession and an avid RC pilot when not at sea. In the RC hobby for 42 years, flying for about 38 of them, fixed wing as well as rotary.
Since about 6 years now, I have completely tossed Methanol out, but.... not given up on the engines I allready had (in fact, gathered a lot more of them, since glow engines nowadays seem to be cheap and plentiful in the classifieds).
Of course the first attempts at flying SMALL gas (really small) were difficult, but nowadays, I think I have the trick mastered, and unlocked the door to the smaller range of engines (15 cc and smaller, down to at least 5 cc, but trying to go smaller even, all the way to 1,5 cc).
Flying on gas works just as well, if not better, than on methanol. Very userfriendly, very reliable, lots cleaner, and very frugal, and converting glow engines means that there is a much wider range of options compared to "purpose built" gassers.
I have now done more or less every displacement size over 5 cc and they all work flawless.
I used to burn through easily the equivalent of 500 bucks per year of methanol, now that has reduced to about 50, no joke, and I am flying more rather than less. The money saved is used to buy more engines

I came here to RCUniverse, seeing that this forum contrary to other forums has a dedicated sub for engine conversions, but to my dissapointment, it is rather quiet in here, looking at the dates of last posts and the average length of threads.
Nobody interested in flying cheap wet fuel anymore? Pity...

Anyway, regards,

Bert

1967brutus

Well, It appears that interest in small gassers is not overwhelming...

For those that do not yet know me from other forums, here are a few examples of what small gassers can be like.

Ease of operation: this is a 5 cc fourstroke, video was shot with stone cold engine, not warmed up, not primed, not run for 24 hrs previously. Engine still has stock carburettor, the mixture is continuously adjusted via a curve programmed in the transmitter, the actual fuel metering is done with a tiny solenoid borrowed from a Stihl M-tronic engine. This is NOT a fluke or lucky shot, it starts like this consistently...

Excellent throttle response in singles: a 100% stock, unmodified ASP .91 2stroke, running a pipe, same set-up with the mixture being controlled via transmitter and fuel metering solenoid.
Excellent throttle response in twins: A 100% stock ASP FT160
And even in radials:

All three with stock glow carbs, and no or only minimal mods to the induction system (NO Ray English, Morris Mini Motors or other commercial mods, nor imitations of it).

My engines do not only work on the bench, they fly too (duh, what would be the point if they didn't?), and as long as a suitable engine is selected, performance is just as good as we are used with glow fuel:


Not yet shown in these videos, but latest development is to integrate automatic mixture correction for ambient temperature and barometric pressure. Still under development (already 2 planes flying with it, testing so far gives positive results).

For what it is worth: I am NOT a vendor, and I do NOT have commercial interests. I will voluntarily share everything I know about the subject, and if needed, any materials I can supply at zero profit, but I would encourage people to try and make their own, it really is not rocket science...

1967brutus

Previous post shows results that came relatively easy.

What DID take an awful lot of effort to get it to run right, was a .50 class heli on gasoline, that turned out to be a multi-year effort, but in the end, it all worked out:


I started this project in 2015 or so, before the first plane engine, and it took about 3,5 years to get it right, sort of.

I would not really reccommend that to anyone but the most adventurous, though. It can be done, the engine has at least 15 gallons through it (and given how frugal it is, that is a LOT of flight time, and more than enough monetary savings to pay for engine, muffler, ignition and a few crashparts), but it also involved quite a bit of testing, trying, re-doing and frustration.

1967brutus

I will close this thread, because the thread title does not really invite a discussion. That is my mistake.

My intention was not to show off, but to demonstrate that converting glow engines to gasoline is not only very doable, but it is doable with very minimalistic means, very worthwhile, and if done properly, absoluty satisfying in performance and convenience.

If anyone is interested, feel free to either start a thread with questions, or to PM me those questions, I won't bite and I do not keep secrets. I will help in any way I can.

1967brutus

Wankels appear to be able to run gasoline as well....

Not yet there, but slowly progressing.

1967brutus

A thermal isolator between engine and carb makes a HUGE difference.


Next step: getting the solenoid system set up, to get the engine to run as lean as possible throughout the RPM range, for two reasons: in this engine, the negative influence of unburnt fuel on the properties of oil is HUGE (and strangely enough, running temperatures drop significantly with a lean mixture), but the 2nd reason is that at part throttle, the lack of fuel metering makes the engine wasteful to the extreme:

1967brutus

Inbetween steps: different props to see how the engine responds
An APC 9 x 6 brings the RPM up by 1100 to 12100 and gives a power increase from 0,4 to 0,44 hp

Going even lighter with APC 9 x 5 brings RPM to 13000 and raises power to 0.46 hp.

The 9 x 5 gives a slightly better static pull, but chances are, the 9 x 6 will perform better in the air. Remains to be determined.

1967brutus

Meanwhile, something I cobbled together a while back, but never got around to tuning it properly.
No idea which kit this is, it's a 59" wingspan Cub, but I cannot find anyone who ever made such kit.
The engine is a Magnum XL52, with several scratches in the liner, but still running pretty good nevertheless. Thinking about getting at least a new liner and a new ring for it.

Note the absolute lack of exhaust smoke on gasoline.

Outrider6

My Feedback: (2)

I am interested in this topic, and would like to see the discussion grow and stay alive.

Here is my issue: I am thinking of scratch building a Goldberg Ultimate biplane. I have considered powering it with a DLE-20 gasoline engine, as that has been done before. However, that engine seems to be a good bit more than this plane needs, which flies great on a 4-cycle 120 glow engine. I would have to make a taller landing gear to accommodate the larger prop that would get the most out of the DLE. Plus, that engine is quite loud, and requires either an expensive aftermarket quiet(er) muffler, or a DIY one.

In summary, I would love to see a 15-18cc (guessing on the displacement) gasoline engine that swings a 14-15" prop and has very comparable power and weight (or lighter) than a 120 4-cycle. In other words, something like a slightly smaller version of a DLE-20.

Do you think an existing model glow engine could be converted to accomplish this, or perhaps an existing 2-cycle gasoline engine from some piece of power equipment?

1967brutus

Assuming that the plane has sufficient power with that 1.20 fourstroke to not need full power all the time, you would be looking at something like a 1.50 fourstroke to convert. Saito has a 1.50 that lends itself very good for conversion, and you will be amazed how userfriendly that engine will become.
ASP, OS, Magnum, they all can be converted just as well, but Saito have the best cooling properties with their cylinder/head in one single casting.

I have done one for a customer, runs pretty good.
Care and attention must be given to proper cooling air ducting ("Baffling"), and fuel plumbing is slightly different than for glow fuel, but nothing "black magic".
I would definitely go for the fourstroke approach because for 2-stroke, this particular power range is a bit of a black hole: not many options between 15 and 20 cc.
But IF you do, I would suggest getting a .91 heli engine, the heatsink head will solve many cooling issues.

Feel free to ask any and all questions, I have no secrets and sharing info is the name of the game.

Outrider6

My Feedback: (2)

Thanks for the info. That gives me lots to think about, along with all of the other issues I will have scratch-building this plane and making design modifications to the airframe (for other reasons). At least now I know what is possible.

I got out of the hobby for many years, back into electric planes a few years ago, and glow planes only last year, so I am having to learn a good bit about modern engine technology. I think it is great that people are keeping this aspect of the hobby alive (as well as actually building planes). I am trying to to my part for the hobby, because without enough people doing this, it will die.

1967brutus

You're very welcome, and as said earlier, don't hesitate to ask, either here or through PM (here is preferred, for the benefit of others reading), and also, there is no such thing as a silly question, apart from the ones you do not ask...

TheEdge

My Feedback: (788)

Wishing you a happy new year Bert.
Thank you for your enthusiasm in bringing before us, your wonderful knowledge.
Happy Landings.

1967brutus

Hey, Cheeky!

Thanks, man! Same to you and your beloved ones!

The great thing about knowledge, is that it is free both to get, and to share, and yet incredibly valuable to those that want it.
Happy to share, and here's hoping a few of you guys will fly gas in the oncoming year.

Trust me, it's worth the hassle!

John_M_

Nice project Brutus, and welcome aboard

1967brutus

Thanks, John!

Chances are, we'll be taking this whole project and associated communications about it to here... RCGroups lately kinda sucks... Unfortunately the source of all that suckiness also haunts these forums, so not sure yet.

cmulder

Quit contributing to that other place. after yet again getting bonus points....

Am waiting to see if those sh 55 liners and pistons fit our "GO" engines. if they do would that mean that these companies are the same or just that they stole eachothers design?
And of cource checking how this aliexpress site works.
Do they charge shipping for each item or if you buy a few of the same just the same?

1967brutus

Cannot comment on the business side of things, and basically I am also guessing on the technical side of it, but it is entirely possible that the designer that worked for GO engines, took his design with him and now works for SH. Or the other way around, the guy that worked for GO back then, originally came from SH. No way of telling unless someone has access to personell files.
Something similar happened when an OS designer started working for Sanye.

I hear you on the "other place thing", but lets keep that out of here...

Brgds, Bert

CW-(ClippedWings)

Hi guys,

I can answer some of your questions, I have a few "GO" .56 engines and a few weeks ago received some SH .55's as well. The cyl. head of the SH is a drop-in replacement for the GO engine, the only mod required is to drill a small hole in the HS .55 head to fit over the GO engine liner pin (1 min. job). No mods required for the GO head to fit on the SH .55.
I can also confirm that the OD of the SH and GO engine liners are the same, I still haven't completed a whole liner/piston conversion yet to see if any mods are required.
The piston geometries are different, the GO engine has a 23mm/21.8mm (oversquare) the HS has 22.3mm/23mm (undersquare).
A few nights ago I checked the diameters of the ASP .52 (22.4mm bore - validated), Thunder Tiger .50H and Redline.53 (22.5mm bore - validated) and SH .55 (22.3mm - validated).
So - if you have an old TT 50H or RL .53 piston ring, don't throw it away! you should be able to take out all scratches and adapt it to fit on the ASP .52HR (if you have the heli version) - a very useful idea since the piston ring of the 52HR is very hard!
I will continue with my experiments and report.

1967brutus

Thanks for that extensive answer, CW, and glad to see you here in the land of the reasonable...

Really good to see you sharing your considerable knowledge on converting glow engines here as well!

prigai

Thanks for your kind words Bert, to complicate matters even further I now resurrected the username I created 17 years ago but with very little use since...
When I got back from work this evening I dismantled one of the Rotorstar Apache (GO .56) I bought from HK years ago.
As said, the liner's diameter is the same as the SH .55, however the piston has 22.3 mm diameter vs. the GO .56 that measured at 22.9 mm.
The lip of the GO .56 liner is 2.6 mm thick vs. the SH .55 of 22.3 mm. a .3 mm gasket between the liner and crankcase will improve things, no doubts.
The transfer ports of the GO .56 are much wider (around x 2) and positioned higher up on the liner.
The boost port starts at a similar height but is also wider on the GO .56. The exhaust port is again, a bit wider and higher.
The wrist pins appear to be at the same height and diameter which makes me think that the SH liner/piston combination is a drop in replacement.
In summary, I think the liner/piston replacement of the GO .56 engine is very feasible alternative and with very little work.
The engine's volume (.56) will be reduced to around .53 but with the ABC setup and 10mm carb it should have decent grunt...

1967brutus

Now that was a username that I would have immediately recognized as being you

Thanks for the explanation on the liner swap, so if I am getting you right, the (ABC) piston and liner of the SH 55 engine should be a possible swap into the GO GH56 with some minor and easy to execute mods like a headshim? Kewl!
I don't need one yet, but it is good to know there is an alternative/it can be done.

prigai

That's correct, however, don't expect the same level of performance as all ports are narrower and lower down the liner, the HS .55 liner/piston appear to be timed for torque rather than high RPM, that would be more suitable for a fixed wing aircraft rather than for a heli.
Interestingly the GH56 piston appears to have a hard coat of material at the top 2/3 of the piston, instead of the usual aluminum finish, probably suggesting it is a hard wearing piston/liner combination and should last for a long time. I would also guess that a piston ring from an OS 55HZ or TT Redline 56 (both 23mm) would be quite easy to modify and use if required.
The GH56 bore on the HK website say 23.35mm, that's incorrect, I have measured it to be just under 23mm.

1967brutus

IIRC, GO claimed to apply some sort of plasma-coating technology or "plasma-infusion" or whatever they called it. I can't recall, but back then I looked it up and it is most definitely some kind of very hiigh tech extremely wear resistant coating. Whatever the case, I know mine has seen and survived sustained 180 deg C head temperatures... It did not run right that hot (vapour locking) but it did not hurt it either.

prigai

That't amazing, I don't think many engines would survive under the same circumstances.
I have great respect for good engineering, I remember reports of this engine operating regularly well past the manufacturer's max. RPM's in a GAUI NX4 with no issues.
Great pity this engine is no longer available...