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Old Apr 05, 2014, 05:22 AM
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That sounds like a good idea, a color sensor. If it doesn't false trigger then it has the advantage of paint being well fastened to the rotating part.
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Old Apr 05, 2014, 12:28 PM
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The Netherlands
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Originally Posted by Chophop View Post
That sounds like a good idea, a color sensor. If it doesn't false trigger then it has the advantage of paint being well fastened to the rotating part.
Nope, it is not a colour trigger.... the window and the painted vane, are just used to confirm timing by means of strobe light.

By the way, we just adjusted another T-rex 600 with this ignition system, and believe it or not, but we managed to do 9 minutes of normal sporting flight on 1/4 of the main tank. Fuel 5% Nitro.

That would mean roughly 30~35 minutes of safe flight on one full main tank (helo is equipped with hoppertank as a reserve)

Before conversion the owner managed barely 12 minutes on the full main tank, containing 15% Nitro fuel...

In this case a total reduction of fuel cost of close to 65% was achieved.

Brgds, Bert
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Old Apr 05, 2014, 03:28 PM
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So as a review, a spark plug ignition system gives THAT MUCH improvement over a glow plug on glow fuel ? It may become very popular then, as it would quickly pay for it's self in fuel savings. Your work makes sense now.
I wasn't looking for such an improvement in gasoline efficiency, but do want to study optimum performance at all throttle settings and no engine stalls.

So now I see Evolution has come up with a 62 cc RC gasser that has EFI.

http://www.horizonhobby.com/products...-efi-EVOE62GXI
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Old Apr 06, 2014, 02:50 AM
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Well.... I never expected this much improvement, to be honest....

I am primarily running older designs, and engines that were intended to run low Nitro fuels anyway. I am seeing the expected 20~30% fuel saving.

It seems, modern 600 designs rely on high Nitro fuels in order to control ignition timing by mixture (basically cooling the combustion chamber to acceptable levels by drowning it in lots of fuel, adding Nitro to keep it igniting and burning "properly").

Because whichever way you turn it, I cannot explain this large volumetric reduction on the chemical properties of 15% vs 5% alone.... So I conclude that excess fuel is used to control the engines running behaviour.

But it is a fact, this helicopter, after adjusting properly, consumed approx 100 cc (little over 2 oz if I'm correct) in 9 minutes of flight.... and we're talking about an OS 55 here....

I expected the engine to be sizzling hot, running so little fuel, but to my amazement it was below 100 deg C when it landed...

This is not what I was expecting, nor what I was aiming for.... I was hoping for about half this, at best.... seems we as modellers have lost sense for engine-efficiency a bit too much, when we decided that "a dash of Nitro makes it run better"

I have full confidence, that this result is repeatable and more or less valid for all modern high performance glow powered helicopters....

I have the feeling (it is nothing more than that) that you need a small amount of nitro still, just for purpose of adjustability, but that is about it....

My next step is allready outlining itself:
I want to build a .30~.40 class fuel powered helicopter with a fuselage (just a simple Jet Ranger, nothing exotic), and see if I can run it with ignition on lower fuel cost than the LiPo-replacement cost for comparable electric drive...

Just to see if it is possible....

But I doubt if it will become popular.... It is a tinkering hobby, but a tinkering hobby in which people somehow prefer to pay for luxury instead of doing the tinkering... A "skill-hobby" in which people prefer to pay for electronics that eliminate the needed skills.
And if for whatever reason, a manufacturer would decide to sell a pre-tinkered, pre-adjusted CDI equipped methanol-burner, people would want to pour gas in the tank, then claim it does not fulfill their expectancy...

I just do this for the fun of it, and if in the meantime I can enable some people to keep their hobby a bit more affordable, that is a nice side-effect....

But I can say here and now: the ignition systems are allready on the market for a long time, and in my opinion, if noise would not have been an issue, CDI and Methanol would have had a very good potential for pushing electric power out of the market: once set-up properly, it is THAT easy, and THAT economic....

Brgds, Bert
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Old Apr 06, 2014, 02:10 PM
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$25 tp $40+ /gallon steered me straight over the bushes to lipo.
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Old Apr 06, 2014, 03:59 PM
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I run a fuel that (due to the CDI) typically costs a lot less than 20 dollar per gallon

With a T-rex 600 that same gallon would last close to 6 hours of flying....

6 hours of flying would also be approx half the useful lifetime of a 40 dollar LiPo....
so 2 gallon of fuel, worth 40 dollar (or less) would give you the same flight duration you could get out of that 40 dollar LiPo... but without the charging, the waiting, the carrying around big lead batteries, charging from your car battery (with an idle running engine against a certain fuel cost), etc etc.

And I can tell you, an Align starter is a lot cheaper than a 200 Watt LiPo charger...

We estimated that the fuel cost per minute, of the T-rex 600 equipped with ignition is only 20% of that of a T-rex running 15% Nitro and G/I, whilst maintaining virtually identical performance level.

Some people run 30% Nitro, and I guess, there will be a small performance loss then, but cost reduction will be beyond imagination....

Brgds, Bert
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Old Apr 06, 2014, 09:43 PM
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I suppose then the timing control is where most of the losses happen in glow engines. I always pictured them as sloppy inefficient but high power propulsion. If the results are repeatable, you really have something here, get manicured for some RC magazine photos.
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Old Apr 07, 2014, 01:55 AM
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I suppose then the timing control is where most of the losses happen in glow engines. I always pictured them as sloppy inefficient but high power propulsion. If the results are repeatable, you really have something here, get manicured for some RC magazine photos.
In my opinion, you're spot-on!

It seems that for helicopters, where in hoover a power consumption of roughly 125 Watt per kilo is a rule of thumb, a 3.5 kilo T-rex 600 equipped with a latest generation OS 55 suddenly gets into the same consumption range per kilo per minute as a 5.5 kilo Vario SkyFox with a 20 year old Rossi, but I did not do extensive measurements to confirm.
On CDI both helicopters seem to consume roughly 200 cc of fuel, per kilogram per hour.
On glow, the heavy Skyfox would consume rougly 350 cc of 2% fuel per kilo per hour, the T-rex however would consume 520 cc of 15% fuel per kilo per hour.
The different Nitro contents only explain away approx 75 cc of this difference, the rest is due this timing control....

That Nitro Methane, stuff is a very expensive way of ignition timing control....

And the power is (for the same fuel) even more compared to glow....
Oh, and yes.... the results are repeatable: My flightschool has 3 heli's with 2-stroke, doing the same, and I sold a few sensors (one of them the above described T-rex).

Currently I am working on a .30 class fuel powered scale helicopter with this ignition (motor is an OS 37 SZ). Purpose is, to take a "portable size" fuel heli, a self contained electric starter (like the Align, with a 3S liPo built in) and a litre of the cheapest glow fuel, and have an afternoon of flying fun, for a lower price than the wear and tear on your otherwise needed LiPo's

Imagine flying SMALL fuel helis, running consistent performance levels and minimum of "needling fuss", for LOW fuelprices, taking with you to the field only the bare minimum....

Brgds, Bert
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Old Apr 07, 2014, 06:45 AM
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trying to get fuel

in a country where rc flying is almost unknown nitro is more difficult to get and rather expensive .
so if you could come up with a ready to bolt in engine for my raptors i would be very happy or even post a shopping list of where to get the parts to build one as long there is no need to machine anything like brackets.

being able to reuse the current engines would be even better (both 30 and 50 class os)
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Old Apr 07, 2014, 10:20 AM
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Originally Posted by cmulder View Post
in a country where rc flying is almost unknown nitro is more difficult to get and rather expensive .
so if you could come up with a ready to bolt in engine for my raptors i would be very happy or even post a shopping list of where to get the parts to build one as long there is no need to machine anything like brackets.

being able to reuse the current engines would be even better (both 30 and 50 class os)
First, just to make it absolutely clear: we are still using methanol (glow fuel), NOT Petrol or Gasoline


As long as that is clear: Yes, you can reuse your current engines: that is what I have done so far exclusively: bolting a CDI system to long time used glow engines, and achieve this kind of results.

You need to do some light machining to the backplate of your engine, or find somebody that can do that for you (or you have to send it to me, then I'll do it for you, but that has a small price. Not the machining itself, because that is fairly cheap, but you get two times shipping cost....)
If you have a friend to do that machining, I'll be happy to tell you exactly what needs to be done.
For somebody with the right tools and that knows what he (or she) is doing, it is less than an hours job to modify the engine for the sparkly business....

The CDI is a bog standard RcExl unit, and I'll leave it up to you where you want to buy that.
The sensor, I make those, and they cost €22,50 ex shipping.
Just to make it clear: the standard included Hall-Sensor from RcExl can NOT be used in THIS application... you need the sensor same sensor as used by me....

But I have to be honest: I have done the modification to a .50, but not yet to a .30, and those .30's become real tiny.
So I would prefer to first get mine up and running, before I sell you a sensor for a .30....

If your engine is an OS.50 or .55, I have the dimensions and can make sensor + bracket for you within a few days.
Like I said, the backplate needs some machining, and preferrably you have to arrange that yourself.

Basically, it comes down to the backplate being machined down to a thickness of less than 1.5 mm (we aim for 1.3 mm) locally where the sensor has to be placed.

as for brackets: you need to fit that ignition box somewhere but that can be done with tie-raps, possibly you have to create some clearance for the plug-cap etc. which is basic use of the good old Dremel, and the bracket that I make for the sensor, is very easy to make for yourself, if you have acces to some epoxy sheet 2mm (like electroninc print board) and the most basic modelling tools like a jigsaw and a small drill. But I'll be hapy to make them for you....

For more info, just PM me....

Brgds, Bert
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Old Apr 17, 2014, 07:21 AM
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It works on a .37 engine as wel....

VVery first start of my OS .37 SZ with electronic ignition (0 min 37 sec)


Brgds, Bert
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Old Apr 17, 2014, 02:12 PM
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You make it look so easy Bert. Very impressive.
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Old Apr 17, 2014, 02:45 PM
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Euh.... it IS easy!

Anybody with a Dremel and a bit of patience, can remove the webbing from that backplate.
With that same dremel, anybody can cut a small strip of epoxy or other suitable material 1/4 x 3/4 inch

Anybody with a small soldering iron and some shrink-tubing can solder a standard Futaba connector to that sensor (you need MLX90217, not the standard RcExl sensor).
Anybody can glue that sensor to a 3 x 10 mm magnet.

Nobody needs a Lathe to make that plastic tube for retaining the sensor: most electric stuff (transistor radios etc) have plastic casings held together by screws. Usually a few of those screws are turned into tubular protrusions. All you need to do is find a discarded or broken Household appliance and recover such protrusion. Drill a fitting hole for the magnet, and voila!

Once that is done:

Buy an RcExl, turn the plug out of the engine, replace for the sparkplug, connect the ignition, connect the battery, connect the sensor, fit the sensor to the engine, and just start....

It is exactly what I did in the above case.

The job is easy.... it was the "figuring out how to..." that was hard, but that I have done for you guys, you just only have to follow....

Brgds, Bert
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Old Apr 18, 2014, 12:04 AM
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USA, IN, Commiskey
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I haven't checked in for a while. Brutus1967 you have found the fix to my failures. The timing magnet was the problem I was having. Thanks to your continued work it looks like we will get to fly a lot cheaper for a long time to come. I will start looking for the sensor to make one for my RcExl ignition. Glad to be back.

Jimmy
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Old Apr 18, 2014, 01:52 AM
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As long as you keep using Methanol and oil, you'll be OK....(and don't worry, the savings will still be anywhere from 50 till 80% on fuel cost....)

Brgds, Bert
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