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HomeAircraftHelicopterGasser Model RC HelicoptersEngines › Glow Plug for gasoline?
02-08-2016 02:33 AM  29 months agoPost 1
RM3

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Killeen, Texas - USA

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Has anybody tried that glow plug that is able to run on gasoline? what is it like?

thinking maybe experiment with one on a high compression 3.5hp modded 20 engine Im planning on making. making the adapter for the plug would be easy.

just not sure what the details are.

showing a preference will only get you into trouble, 90% of everything is crap...

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02-08-2016 05:39 PM  29 months agoPost 2
turboomni

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East of the Equator

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I believe OS already does this.

Setup is everything, All my heli's can fly far better than I can pilot them

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02-08-2016 05:40 PM  29 months agoPost 3
turboomni

rrProfessor

East of the Equator

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delete

Setup is everything, All my heli's can fly far better than I can pilot them

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02-08-2016 05:51 PM  29 months agoPost 4
ICUR1-2

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Ottawa, Ontario

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I have seen videos of nitro engines converted to gas still using the glow plug and have read that some use a hot plug and some keep it powered.

spending time, paying attention

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02-08-2016 08:12 PM  29 months agoPost 5
RM3

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Killeen, Texas - USA

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Ive read all sorts of things on them...one issue some say they have is that the idle is high, others say that depending on the idle depends on whether or not you power the plug or not after warm up...

just need to know if anybody has actually run the them...conversion or otherwise.

showing a preference will only get you into trouble, 90% of everything is crap...

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02-08-2016 09:50 PM  29 months agoPost 6
turboomni

rrProfessor

East of the Equator

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There must be a catalytic effect or no ? I wonder if ethanol gasoline helps or hurts performance.

Setup is everything, All my heli's can fly far better than I can pilot them

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05-10-2016 02:54 AM  26 months agoPost 7
whiskey29

rrNovice

Samarinda

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Watch at YouTube

OS g5, engine NGH gt25.
Transition after long idle is acceptable for sport flight.
I didn't measure RPM or how low the idle was.

Transition problem solved with velocity stack.

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05-10-2016 04:58 AM  26 months agoPost 8
rbort

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Franklin, MA - USA

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Rpm
Looks like the low idle is unstable at slow speeds below 2k, when it was stable it sounded like 2300-2400 rpms.

Full throttle the rpms are too slow, the engine needs to peak more. So if its already tuned then you need a smaller prop.

-=>Raja.

MA 1005 Hanson 280, 4210 flts
Spectra 27 3DMax, 3288 flts
Whiplash V1-2 Hanson 300, 1570 flts
Whiplash V2 Hanson 300, 402 flts

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05-10-2016 01:37 PM  26 months agoPost 9
whiskey29

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Samarinda

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Thanks Raja for the tips
The unstable low idle might be caused by my fingers, I will try to measure RPM next time. To be honest I don't even remember how fast it ran with CDI but I could look around for comparison.

However, I am sure it ran better with CDI.

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05-16-2016 01:03 PM  26 months agoPost 10
brw0513

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Brisbane, Australia

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I have an OS GT15HZ600 engine that I've been running in on a test stand with a 12x6 then a 12x4 prop. Using Coleman fuel and a good quality fully synthetic oil at 25:1.

As an experiment, I purchased a GGT15 head and G5 plug and fitted both to GT15HZ600 engine. To my surprise I couldn't tell the difference with how the engine ran.

At the time of this experiment the engine was still rich at both idle to mid-speed as well as at WOT.

I burned up the G5 plug on the second run, but it was my fault. Stupidly, I forgot to install it more than finger tight before starting the engine

I think this could work and I will be persisting with the experiment.

Issue No 267 of Australian magazine "Airborne" has an article written by Brian Winch on a similar topic. From memory, most engines go well if originally designed for petrol with spark ignition. Otherwise carb design and compression ratio play a role.

Ian B

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05-24-2016 01:00 AM  26 months agoPost 11
thtoyman

rrKey Veteran

Gone ,Flying.

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I would like to kown more

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05-24-2016 04:32 AM  26 months agoPost 12
RM3

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Killeen, Texas - USA

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I had a creepy event one day while testing a modded engine on a test stand with a prop that had high compression....the butterfly on the carb got suck at about 75% open....so to shut it off I pulled the NiMh pack off the CDI...and the engine kept running as if the ignition was still powered... I could tell the difference, the rpms dropped a bit, but it was still running strong...I ended up plugging up the carb inlet with my palm to kill it.

so a glow plug would seem to be a viable solution should you want to get rid of the weight of a CDI...

performance wise my guess would be that it would not give as much power as a timed electronic ignition.

showing a preference will only get you into trouble, 90% of everything is crap...

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05-24-2016 04:45 AM  26 months agoPost 13
turboomni

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East of the Equator

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Does a CDI have variable timing or any kind of closed loop info? If not a CDI it would be a crap shoot which is better between a glow plug or the CDI. Both seem to be non reactive. Boils down to the fuel I would think.

Setup is everything, All my heli's can fly far better than I can pilot them

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05-24-2016 10:24 PM  26 months agoPost 14
RM3

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Killeen, Texas - USA

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as far as I know the RCexcel unit has auto advance.... but its just a basic delay circuit that is timed off of the 27 degree advance that the mag sensor has in relation to TDC... the faster the engine rotates, the less of a delay the CDI imparts before ignition...therefore the max advance is determined by that position of the magnet sensor in relation to TDC...

Im sure the glow version is based solely on physics and pressure/temp as well as catalytic reaction based on fuel content....so it cant be as good as the CDI.

Therefore any (if any) advantage would be based on weight savings over power gained by use of a CDI...

showing a preference will only get you into trouble, 90% of everything is crap...

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05-25-2016 01:52 AM  26 months agoPost 15
rbort

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Franklin, MA - USA

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Maybe
Therefore any (if any) advantage would be based on weight savings over power gained by use of a CDI...
Well take for example the zenoah engine we use in our helicopters. You can run it with a magneto, or you can get the RCexcel unit to run it. The magneto system will literally run forever, its like 99% reliable hardly ever any issues with it, and if you have the gas it will run with no limits.

The RCExcel system now needs an extra battery to run it, and to be honest the reliability factor of it is not nearly as good as the magneto system, having used both. Sometimes its more finniky to start, sometimes it can cut out, or even fail causing you to replace the unit. I'm not saying its an everyday occurence, but it does happen from time to time.

Then you need to maintain and charge that ignition battery, or you could get yourself a second regulator for your generator system if you were using that and just run the ignition endlessly on the generator. You could also conceivably ditch the ignition battery all together if you have a generator, as if the motor is turning to turn the generator it will make its own power to power the ignition, though you lose some redundancy if the generator was to fail for some reason, like the coupler got loose on you for example, could quit the motor. Here is a video of that to show when I had this setup and you can see it running with no battery for the ignition as well:

Watch at YouTube

So as far as weight savings, I'd say not much as you remote the flywheel to put the CDI, but you have to add an ignition battery and the ignition system, so maybe you save an ounce or two tops.

As far as power gained by the CDI, I'm not really sure how much that would be as I never compared, but you can run a zenoah engine with the magneto, take it off and run it with the CDI to compare, though I'd guess that it isn't much either. If you did this test ideally should be done on the same day at the field, though that might be harder to do its would be more accurate than coming back another day.

Lastly, engines with the electronic ignition (especially helicopter ones) lack the mass to make them smoother at slow speeds. They are OK at flight rpms, but at idle they are not going to be as good. Remember that the PUH engine was OK, but the RC engine improved on that due to the bigger fan and more mass. The CDI engine would be worse than the puh, more rough and could shake things loose on your heli if you spend alot of time idling (say doing alot of autos). Again its not a major factor, but I'm just pointing out all the little things to consider.

At the end of the day for me, I prefer the magneto engines as they are trouble free for years and thousands of flights later they are still running like a champ. I had more issues with the CDI engine than all the magneto engines I flew put together.

For the record, CDI in airplane engines works better than magneto as you can hand start easily and also the prop gives the mass for smoothing out the pulses. Different animal there than in heli engines.

Edit: In watching the video above, about 2 minutes in watch me start that zenoah engine with the RCExcel ignition. First pull OK it didn't catch, 2nd pull it starts, but then it quits. Why? Third pull runs a little and quits again, 4th pull same thing. I raise the trim, finally get it to run but then it speeds up a few seconds later meaning the trim was too high. Why didn't it keep running the first time it caught? Magneto system it would keep running no worries. A little bit more finniky with electronic ignition.

-=>Raja.

MA 1005 Hanson 280, 4210 flts
Spectra 27 3DMax, 3288 flts
Whiplash V1-2 Hanson 300, 1570 flts
Whiplash V2 Hanson 300, 402 flts

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05-25-2016 04:38 AM  26 months agoPost 16
RM3

rrElite Veteran

Killeen, Texas - USA

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The weight of the magneto system and the weight of the CDI and associated power supply are both similar in a PUH...the RC engine format has a significant weight penalty IMO, but is off set to some degree by gains in smoother power delivery and significantly better cooling system.

but we are comparing them to a glow ignition, that requires no magneto and no CDI system... that alone is a significant savings in weight....

Besides Raja, your engine issue of failing to start on the first pull cannot be attributed to ignition alone....you above all should know that.

Reliability is another issue entirely and not the focus of this thread. Difference in engine performance is.... if we can get rid of the CDI, extra battery (or use a smaller one to only power the servos/rx/gyro) and get a lighter Heli and do away with associated ignition issues like EMI and component placement and only loose a tiny bit of engine power all while still running cheap gasoline would that not be a gain worth having?

showing a preference will only get you into trouble, 90% of everything is crap...

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