I don't think you need to glow the plug white hot. Regular glow plug on 1.2V (at 2.2A) runs fine. If voltage drops below 0.9V then it will be to cold to fire. Anythng between is OK. Higher than 1.2V will only shorthen the life of the plug.

RysiuM

I agree with RysiuM. 1.2 volts is plenty. I just competed 4 long flights on my FETS (Flying Engine Test Stand). And everything worked very well. Easy starts, good ecceleration, good top end. I was running plain regular gasoline (87 octane) and 50:1 Amsoil. I used the original OS F plug and it is still working fine after about four 14 ounce tanks of gas. I did notice a fine white coating on the plug but it still glows bright. It was about 85 degrees with normal humidity for here in Oklahoma. I tried everything I could do to get the engine to fail but it just kept running until the last flight. I had made a homemade plug connector and that failed in flight. I didn't know that it had failed until I slowed down to land and the engine quit. After I landed I noticed the wire hanging down and reallized that I had lost the glow. What I just said was that the engine kept running at full throttle with the glow off. Didn't quit until I tried to throttle down for landing.

So in conclusion, I still havn't found the down side of this system on my Robin 24.5cc conversion engine. You must keep the plug glowing at all times. Reliablity depends on the glow plug. I will continue to test the plug to failure.

What do you use for FETS?

RysiuM

My FETS (flying engine test stand) is a scratch built enlarged Ugly stik. I have a set of the original Ugly Stik plans on CADD and can make them any size I want. The wingspan is about 80". Big and boxy but flies like a Stik. Just perfect for these 25-31cc conversion engines. I like how it flies so well that I have started taking it out to fly just for fun. The photo shows the business end. I use a universal mounting plate so that I can mount about any engine. There are two throttle servos so that I can have carb on either side of the airplane.

I run the new cut Poulan 25 today on gas-methanol mixture trying to tune the carb. Engine started by flipping the prop right away however it was runnig ritch. I tried to tune it but still the full throttle was quite rough. I played with low and high setting as finally engine died. I couldn't start it any more. The reason - glow plug burned. I put new OS long (F) plug and tried to run in just on gasoline. Engine started by flipping the prop and it was easy to tune. I got reliable idle around 1700 rpm and WOT 7200 rpm with APC 17x6. This is all from the new cut engine that weights all together (with muffler and radial mount) 37.5 oz. For glow battery I used GP 3700mAh NiMh that weights 2.3 oz. So here is the performance of 40 oz power plant.

I think this 17 inch prop still puts to much load on the engine. I will buy APC 16x4W that should unload the engine over 9000 rpm (I hope). If so, that might be something good for Funtana 90 (maybe).

RysiuM

Nope I just tried APC 16x4W. Engine unloads to 8100 rpm. That's it. Calculated HP it has much less than with bigger prop. I guess, I just hit the rpm limit set by porting timing or ignition timing. That puts APC 17x6 on the top of all APC prop for this engine. I mean for thrust, not speed.

However good news is that I was still able to start the engine by flipping the prop. Setup the same as the last time: glow plug powered from 1.2V NiMh, gasoline with Motul oil 1:32

RysiuM

Another test with APC 17x6. The engine equipped with the same OS F (long) plug but this time running on gas-methanol mix. I was a little lazy and I mixed 2 oz of methanol with Castrol racing oil for 1:30 and I added 2 oz of pre-mixed gas with Motul 1:30. The result liquid was not clear but no visible layers.

I believe engine will start by hand but as I had to change needle stettings I just used starter. After setting the carb for the best run, I got 7400 rpm (200 more than on gasoline-oil fuel). The iddle was quite reliable around 1800 rpm.

Than I removed power from the glow. The engine didn't drop rpm at all. I got all the range 7400 - 1800 rpm engine running smooth.

So Now I can confirm that gas-methanol mix can run without power on glow plug. However I didn't get much more power tho.

RysiuM

Does anyone know if Pennzoil two stroke oil or Amsoil two stroke oil will mix with a 50% E-85--50% gasoline mixture??

Sorry if that was covered here somewhere and I missed it....

Thanks,
AV8TOR

I mixed 65% of my 50:1 gasoline/Amsoil with 30% Ethanol and 5% ether. It mixed well and stayed in solution. Gas + Amsoil + Ethanol would NOT stay in solution. It seperated into two layers. The mixture with Ether runs pretty good in a 23cc Kawasaki. I'm getting 8100 on the top end with an APC 16/6 and 1800 at idle. It won't idle below 2000 without power to the glow plug. I'm using an old well used OS plug. Next I'll try it with a new OS-F plug.

I tried the 50/50 gas methanol today. The motor ran good but not as good as 20% glow fuel. I am hoping to smooth out the motor on lower RPMS.

On glow it runs smooth (doesnt vibrate too bad)
On gas it runs ok but vibrates BAD and cant get RPMS below 2000 on idle.
On 50/50 gas methanol runs good moderate vibrations and will idle down to 1700.

On 50/50 I had to lean out the top end to almost closed to lean it out enough but the low end stayed almost the same.

I think I am going to stay with 50/50 because I dont like to clean glow off the plane.

Does either help on the idle?

When you say 20% glow what do you mean by that 20% oil or 20% nitro? If you can get some nitromethane mix it at 3-5% with your 50/50 blend and your engine will run much much better and smoother: the other thing you can do is to mix your 20% nitro fuel at a 3:1 ratio with methanol and the mix it with your gasoline at 50/50 blend once mixed that should give around 2.5% nitromethane and about 2.25 to 2.5 % of oil content which means about a 40:1 oil ratio (75% methanol and 25% glow fuel = 3:1 ratio) you won't need to add oil to the mixture because the glow fuel is already providing that, usually glow fuel contains about 18-20% oil.
But I am glad to hear the results that other people like your self are getting, and to know that this experiment can lead us to a cheaper way to reduce weight in our engines and at the same time increase a little bit these engines performance without having to do a lot of modifications to the engine.
Lets keep this tread alive and interesting for the benefit of us modelers. I know that there are allot of skeptical people out there but didn't Columbus, Copernico and allot of other people or scientists face the same skepticism? so go for it.

Hey AV8TOR did you received my e-mail reply? drop me a line!!!!

Hi gsmit6879!!! do us a favor and if you can get some methanol try the 50% gasoline and 50% methanol mixture on you 4 stroke and see how it works that would be interesting to see if you can get a better low idle without the constant current on the glow and also to see if you get better rpms from the mixture?

Guys,

Do you know what is the max safe rpm of 25cc weed whacker engines (like my Poulan 25)? I would like to try 50-50 gas-methanol mixture on APC 16x4 (the ignition timing should be better) or even add some nitro but I don't know it this engine will survive anything above 8k rpm.

RysiuM

I'm a bit confused about what oil I can use with the methanol. I am currently using Amsoil 50:1 mix with my gasoline. The 2 stroke Robin runs great on that mix with full time glow. I will try to get some Klotz to try with methanol and let you guys know how it works.

I checked this fuel after it was sitting in the fuel tank for three days. Now it is clear and no visible layers. I guess Castrol Racing Oil needs some time to disolve in methanol.

RysiuM

Aeronut... never received an e-mail. PM me here and we'll hook back up.

Antique... Thanks for the Amsoil/ethanol info.

Anyone know if Pennzoil for aircooled motors will mix with a 50/50 E85 ethanol and gasoline mixture???

Thanks,
AV8TOR

You can also use a 50/50 mixture of castor and whatever 2 stroke synthetic oil you have available then use your desired oil ratio with the fuel blend(50/50 gas/methanol)

Hey RysiuM I am doing 8400 rpm with a 15x8 MA on my FeatherLite 25 and I haven't had a problem so far, the only thing I am guessing is that the higher the rpm's the wear on the engine's cylinder would be greater

Is it on gasoline or gas-methanol 50-50 mixture?

RysiuM

it's on the 50/50 fuel blend

Then I may try APC 16x4 prop again, but this time on that mixtutre. Methanol might advance ignition a little to boost extra couple hundreds rpm.

RysiuM

Cylinder wear should not be a problem....if you got about the right amout of oil in fuel. Keep up the good work. Capt,n

Is all of this really worth all of the trouble guys?

You still have to search for a special fuel
You have to mix it just right
You may have to keep your glo plug powered all the time

You might as well just give it up and run a spark plug and normal gas/oil mix
The whole idea of going to a gasser is to eliminate a lot of the unreliabilities of a glow engine

But if you guys are really that desperate to give this a go, well, hope you don't get too mad when you plant your motor 6" into the dirt cause it died on ya...

There are a couple major benefits:
1. Cost. Glow plug cost the same a spark pug, but doesn't need expensive ignition module.
2. Weight. Glow plug is twice lighter than spark plug. Same battery but no ignition module (at least 4 oz).
3. Power. In my example I get more power from glow plug than a standard magneto.
4. Reliability. As long as you keep the glow red you have it running. The same is with spark plug - dirty plug (or short) and no fire.
5. RF interference. Glow doesn't do any.

All is for standard gas-oil mixture. Going to gas-mathanol you will get more power and can skip on-board battery but glow is then less reliable.

RysiuM